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Home , Churchill Mountains, Dicroidium, Helm Glacier, Lashly Formation, Mount McMaster, Ohio Range

Order Number 9307776

Sedimentologic, mineralogic, and geochemical evaluation of the provenance and paleoclimatic record of mudrocks from the Beardmore area,

Homer, Timothy Charles, Ph.D. The Ohio State University, 1992

UMI 300 N. Zeeb Rd. Ann Arbor, MI 48106 SEDIMENTOLOGIC, MINERA LOGIC, AND GEOCHEMICAL EVALUATION OF THE PROVENANCE AND PALEOCLIMATIC RECORD OF PERMIAN MUDROCKS FROM THE AREA, ANTARCTICA

DISSERTATION

Presented in Partial Fulfillment of the Requirements for

the Degree Doctor of Philosophy in the

Graduate School of the Ohio State University

By

Timothy C. Homer, B.S., M.S.

*****

The Ohio State University

1992

Dissertation Committee: Approved By:

Dr. Lawrence A. Krissek

Dr. James W. Collinson

Dr. Gunter Faure Advisor Department of Dr. David H. Elliot Geological Sciences Copyright by Timothy C. Homer 1992 ACKNOWLEDGEMENTS

I wish to thank the members of my committee for their guidance during my work at Ohio State. Their critical review during early phases of the project helped shape my ideas, and resulted in a better dissertation. Special appreciation is extended to Larry Krissek for offering sound scientific advice when I needed help, and letting me progress on my own when I had an idea to explore. I also acknowledge the financial support and long term guidance given by Jim Collinson.

This work was funded by National Science Foundation Grants DPP 84-18354 and

DPP-8817023. Additional financial assistance was obtained through an Arco Oil and Gas Company research grant, the Shell Oil Company Fellowship and research grant at The Ohio State University, and a Geological Society of America research grant.

Special love and appreciation go to my wife Toni. She gave me the moral and financial support to pursue my studies at my own pace, and never questioned my judgement. In her own way, Toni has worked hard to make this dissertation possible, and I share the results with her. VITA

May 19, 1957 ...... Born - Boston, Massachusetts

1979 ...... B. S., Geology Bucknell University Lewisburg, Pennsylvania

1979-1980 ...... Mud Logger Core Laboratories Midland, Texas

1980-1981 ...... Exploration Geologist J. W. Humbard and Associates Midland, Texas

1981 ...... Mud Logger Advance Consultants Midland, Texas

1983 ...... Geologist/Engineer U. S. Forest Service Baker, Oregon

1983-1984 ...... Teaching Assistant Texas Tech University Lubbock, Texas

1985-1987, 1988-1989, 1990 ...... Research Assistant The Ohio State University Columbus, Ohio

1986 ...... M. S., Geology Texas Tech University Lubbock, Texas

ut 1988 ...... Shell Fellow The Ohio State University Columbus, Ohio

1989-1992 ...... Teaching Assistant The Ohio State University Columbus, Ohio

PUBLICATIONS

Homer, T. C., and Krissek, L. A., in press, Statistical analysis of geochemical patterns in Fine-grained Permian sediments from the Beardmore Glacier region, Antarctica: Sixth International Symposium on Antarctic Earth Sciences, Ranzan-Machi, Japan.

Krissek, L. A., Homer, T. C., Elliot, D. H., and Collinson, J. W., in press, Stratigraphy and sedimentology of vertebrate bone-bearing beds in the (and ?) Fremouw and Falla Formations, Beardmore Glacier region, Antarctica: Sixth International Symposium on Antarctic Earth Sciences, Ranzan-Machi, Japan.

Krissek, L. A., and Homer, T. C., 1992, Paleoenvironmental controls on Permian sediment production along the paleo-Pacific margin of Antarctica: evidence from geochemistry, paleo-slopes and paleosols: Geological Society of America Abstracts with Programs, v. 24, p. 193.

Homer, T. C., and Krissek, L. A., 1991, Sedimentology, thermal alteration and organic carbon content as factors in paleoenvironmental interpretation of fine-grained Permian elastics from the Beardmore Glacier region, Antarctica, in Elliot, D. H., ed., Contributions to Antarctic Research II: American Geophysical Union Antarctic Research Series, v. 53, p. 33-65.

Homer, T. C., and Krissek, L. A., 1991, Permian and Triassic Paleosols from the Beardmore Glacier region, Antarctica: Antarctic Journal of the United States, v. 26, no. 5., p. 7-8.

Homer, T. C., and Krissek, L. A., 1991, Geochemical and statistical analysis of Permian mudrocks from the Beardmore Glacier region, Antarctica: Geological Society of America Abstracts with Programs, v. 23, no. 5., p. 70. Krissek, L. A., and Homer, T. C., 1991, Clay mineralogy and Provenance of fine grained Permian elastics, central , in Thomson, M. R. A., Crame, J. A., and Thomson, J. W., eds, Geologic Evolution of Antarctica: Cambridge University Press, p. 209-214.

Homer, T. C., and Krissek, L. A., 1990, Sedimentologic implications of the geochemistry of fine-grained Permian sediments from the Beardmore Glacier region, Antarctica: Geological Society of America Abstracts with Programs, v. 22, no. 7, p. 318.

Homer, T. C., 1990, Distribution of total organic carbon and controls on its occurrence within the , central Transantarctic Mountains: Geological Society of America Abstracts with Programs, v. 22, no. 5, p. 14.

Homer, T. C„ and Krissek, L. A., 1989, Organic carbon characteristics in the Permian Mackellar Formation, central Transantarctic Mountains: Antarctic Journal of the United States, v. 24, no. 5., p. 17-19.

Homer, T. C., and Jacka, A. D„ 1989, Rock fabric as a control on dolomitization and paragenesis in the Mission Canyon Formation of the Williston Basin: Geological Society of America Abstracts with Programs, v. 21, no. 5, p. 95.

Homer, T. C., and Krissek, L. A., 1989, Paleogeographic interpretations using organic carbon and mineral abundance patterns in the Permian Mackellar Formation, Antarctica: Geological Society of America Abstracts with Programs, v. 21, no. 4, p. 15.

Krissek, L. A., and Homer, T. C., 1989, Geochemical indicators of provenance in fine-grained sediments of the Permian Beacon Supergroup, Central Transantarctic Mtns., Antarctica: Geological Society of America Abstracts with Programs, v. 21, no. 6, p. 347.

Krissek, L. A., and Homer, T. C., 1988, A preliminary study of REE distributions in mudrocks of the Permian Beacon Supergroup, Central Transantarctic Mountains: Evidence for early development and preservation of LREE enrichment: American Association of Petroleum Geologists Bulletin, v. 72, p. 208.

Krissek L. A„ and Homer, T. C., 1988, Geochemical record of provenance in fine grained Permian elastics, central Transantarctic Mountains: Antarctic Journal of the United States, v. 23, no. 5, p. 19-21.

v Homer, T. C., and Krissek, L. A., 1987, Depositional environments of the Permian Mackellar Formation, central Transantarctic Mountains: A synthesis of field data and mineralogy: Cambridge, England, Fifth International Symposium on Antarctic Earth Sciences Abstracts, p. 70.

Krissek, L. A., and Homer, T. C., 1987, Clay Mineralogy and provenance of fine-grained Permian elastics, central Transantarctic Mountains: Cambridge, England, Fifth International Symposium on Antarctic Earth Sciences Abstracts, p. 82.

Krissek, L. A., and Homer, T. C., 1987, Provenance evolution recorded by fine grained Permian elastics, central Transantarctic Mountains: Antarctic Journal of the United States, 1987 Review, v. 22, no. 5, p. 26-28.

Krissek, L. A., and Homer, T. C., 1986, Sedimentology of fine-grained Permian elastics, central Transantarctic Mountains: Antarctic Journal of the United States, 1986 review, v. 21, no. 5, p. 30-32.

HELD OF STUDY

Major Field: Geological Sciences TABLE OF CONTENTS

ACKNOWLEDGEMENTS...... ii

VITA ...... iii

LIST OF TABLES ...... xi

LIST OF FIG URES ...... xiv

CHAPTER PAGE

I. INTRODUCTION...... 1

Statement of P u rp o se ...... 1 Study A r e a ...... 5 Previous W o r k ...... 5 Pre-Permian Geologic History of the Beardmore Glacier Region . . 7 Basement G eology ...... 11 Beacon Supergroup ...... 13 (?)/Permian to Lower Triassic Stratigraphy .... 14 Present-day Physiography of the Transantarctic Mountains .... 23

II. SEDIMENTOLOGY...... 25

Introduction ...... 25 Pagoda Formation ...... 26 Mackellar F o rm atio n ...... 34 Fairchild F o rm a tio n ...... 49 Buckley Formation ...... 53 S u m m ary ...... 60 III. ORGANIC CARBON EVALUATION...... 63

Introduction and Purpose ...... 63 M e th o d s ...... 65 R esults...... 71 Vitrinite Reflectance Analyses ...... 71 Kerogen Type A nalyses ...... 73 Total Organic Carbon A n a ly se s ...... 79 Carbon/Sulphur Analyses ...... 79 Discussion...... 82 Controls on Organic Carbon Distribution in Beacon Sediments . 82 Vitrinite Reflectance as an Indicator of Thermal Alteration . . . 87 Total Organic Carbon Content as an Indicator of Thermal Alteration ...... 90 Organic Carbon Content in Least-Altered Zones as an Indicator of Paleoenvironments and Organic Productivity ...... 98 Organic Carbon Content, Paleoenvironments, and Productivity . . 99 Organic Carbon Content and Local Depositional Environments . .105 Sum m ary ...... 108

IV. SEDIMENTARY GEOCHEMICAL EVALUATION...... Ill

Introduction ...... I ll Approach to Interpretation ...... 112 Diagenetic and Thermal Alteration as Controls on Mudrock Geochem istry ...... 112 Organic Carbon Content as a Control on Mudrock Geochemistry . 114 Mineralogy and Grain Size as Controls on Mudrock Geochemistry ...... 115 Sedimentologic Controls on Mudrock G eochem istry ...... 116 Paleoclimate and Provenance as Controls on Mudrock Geochemistry ...... 117 Multivariate Statistical Methods and Analysis of Mudrock Chemistry ...... 120 M e th o d s ...... 122 Field Sampling and Sample Preparation...... 122 Elemental Analysis ...... 123 Results and D iscussion ...... 127 Results of Analysis of Factors that Control Mudrock Chemistry . 128 Results of Provenance and Paleoclimate Analysis in the Beardmore Glacier R e g io n ...... 149 Results of Multivariate Statistical Analysis ...... 167 Summary and Conclusions ...... 181

viii V. MINERALOGY ...... 187

Introduction ...... 187 Factors that Control Mineral Distribution in Mudrocks ...... 189 Mudrock Mineralogy and Source Area L ith o lo g y ...... 189 Mudrock Mineralogy and Paleoclimate C onditions ...... 191 Mudrock Mineralogy and Depositional P r o c e s s e s ...... 195 Mudrock Mineralogy and Post-Depositional Alteration ...... 198 M e th o d s ...... 203 Results and D isc u ssio n ...... 207 Results of Bulk Mineralogic A n a ly s is ...... 207 Results of Dlite Crystallinity M easurem ents ...... 223 Results of Elite Polytype Identification ...... 228 Conclusions ...... 228

VI. LOWER TRIASSIC PA LEO SO LS...... 231

Introduction ...... 231 Field Study ...... 231 R esults...... 232

VII. SUMMARY AND CONCLUSIONS ...... 238

Sedimentology ...... 238 Organic C arbon ...... 240 Inorganic Geochem istry ...... 244 M in e ralo g y ...... 248 Lower Triassic Paleosols ...... 250

LIST OF REFERENCES...... 251

APPENDICES

A. Organic Carbon D a ta ...... 267 Complete results of vitrinite reflectance analyses ...... 268 Complete results of organic carbon a n a ly s e s ...... 271 B. Inorganic Geochemical D a t a ...... 277 Reproducibility of geochemical d a t a ...... 279 Replicate elemental a n a ly s e s ...... 284 Complete results of elemental analyses ...... 294

ix Relationship between vitrinite reflectance and representative carbon-normalized elemental a b u n d an c es ...... 303 Relationship between representative elemental abundances and proximity to intrusive b o d ie s ...... 309 Relationship between representative elemental abundances and organic carbon c o n te n t ...... 315 Relationship between transition metal abundances and organic carbon c o n t e n t ...... 321 Relationship between representative carbon-normalized elemental abundances and normalized SiOz co n ten t ...... 327 Relationship between representative carbon-normalized elemental abundances and normalized A120, content .... 333 Relationship between representative carbon-normalized elemental abundances and normalized FejO, content .... 339 C. Mineralogic D a t a ...... 345 Complete results of x-ray diffraction analyses ...... 346 Boehmite-normalized relative mineral abundance data .... 352

x LIST OF TABLES

Table Page

1 Comparison of stratigraphic sections and section names described by previous workers in the Beardmore Glacier region, Antarctica . . . 8

2 Lithologic summary of the Pagoda Formation, Beardmore Glacier region, A ntarctica ...... 27

3 Lithologic summary of the Mackellar Formation, Beardmore Glacier region, A ntarctica ...... 35

4 Lithologic summary of the Fairchild Formation, Beardmore Glacier region, A ntarctica ...... 50

5 Lithologic summary of the Buckley Formation, Beardmore Glacier region, A ntarctica ...... 54

6 Stratigraphic summary of vitrinite reflectance data. Vitrinite reflectance does not vary significantly between the four studied formations . . . 72

7 Geographic summary of vitrinite reflectance data. Mean vitrinite reflectance is lowest in the far northern edge of the study area, increases toward the central region, and decreases again in the far south. . . . 74

8 Results of kerogen type analysis. Sample names follow the convention described in Figure 6. Vitrinite and inertinite are the most common kerogen groups, and indicate a terrestrial source for the carbon compounds found in Beacon sediments ...... 75

9 Complete results of carbon/sulfur analysis. Samples names use the abbreviations described in Figure 6. Samples are grouped by formation and informal subunit, and means and standard deviations are determined for each g r o u p ...... 80

xi 10 Comparison of loadings from unaltered and altered sample sets. Samples are categorized as relatively unaltered or relatively altered on the basis of vitrinite reflectance data, in order to examine elemental mobility during thermal alteration ...... 178

11 Reproducibility data for peak area measurements of quartz, boehmite and phyllosilicate minerals. Mite, chlorite, quartz and boehmite peak area measurements are reproducible to within 11% of the mean . . 209

12 Reproducibility data for peak area measurements of feldspar minerals. Values for all feldspar and plagioclase (27.79°-28.05° 20) have acceptably low coefficients of variation. Values for plagioclase (22.05° 20), K-feldspar and microcline have high variability, and are excluded from further a n a ly sis ...... 211

13 Stratigraphic summary of mean relative mineral abundance data for the four studied formations and eight informal subunits. Changes in ratios of quartz to clay indicate higher quartz contents in the Pagoda and Buckley Formations than in the other units ...... 214

14 Results of vitrinite reflectance analysis. The first three characters of each sample name indicate the section of origin, and informal subunits for each formation are designated by the following abbreviations: LP= "lower" Pagoda, UP= "upper" Pagoda, LM= "lower" Mackellar, UM= "upper" Mackellar, LF= "lower" Fairchild, UF= "upper" Fairchild, LB= "lower" Buckley and UB= "upper" Buckley. Numerals in the sample name report the height above the base of the section ...... 268

15 Results of organic carbon analyses. Sample names follow the convention described in Figure 14. Individual organic carbon contents have high variability, but averaged values show an upsection increase in T.O.C ...... 271

16 Data from replicate analysis of precision, accuracy and reproducibility for major, minor and rare earth elements. Sample ID follows the convention established in Figure 1 4 ...... 284

17 Complete results of elemental analyses for major, minor and rare earth elements from the Beardmore Glacier Region, Antarctica. Sample ID follows the convention established in Figure 1 4 ...... 294

18 Raw data from semi-quantitative x-ray diffraction analysis of Permian mudrocks from the Beardmore Glacier region, Antarctica ...... 346

xii 19 Complete results of relative mineral abundance calculations. Boehmite- normalized peak areas are listed for minerals that have a coefficient of variability less than 2 0 % ...... 352 LIST OF FIGURES

Figure Page

1 Location of study area and measured stratigraphic sections in the Beardmore Glacier region, A n ta rc tic a ...... 6

2 Map of basement geology in the Beardmore Glacier region, Antarctica: From Gunner, 1983 10

3 Stratigraphy of Carboniferous!?) to Lower Jurassic sediments in the Beardmore Glacier region, Antarctica. The Pagoda, Mackellar, Fairchild, Buckley and Fremouw Formations are examined in this s t u d y ...... 15

4 Time-space diagram from Isbell (1990) shows the lithologic similarity of Permian sediments in the Transantarctic Mountains ...... 17

5 Map from Isbell (1990), originally modified from Elliot (1975a), illustrates geographic locations along the Transantarctic Mountains . 18

6 Diamictite-dominated measured section from the Pagoda Formation, Moore Mountains section MMP. Diamictites are an end-member in the range of glacial deposits, and indicate ice advance or retreat .... 29

7 -dominated measured section from the Pagoda Formation, Cherry section CHI. are an end-member in the spectrum of glacial deposits and indicate deposition by moving water. See Figure 6 for k e y ...... 31

8 Pagoda measured section illustrating the fine-grained end-member in the range of glacial deposits, Clarkson Peak section CPZ. Fine-grained sediments indicate deposition in pro-glacial ponds. See Figure 6 for k e y ...... 33

xiv 9 Mackellar measured section MMC (ML Weeks) showing the large-scale coarsening-upward pattern that is typical of the Mackellar Formation. Smaller scale coarsening upward and fining upward sequences are visible within the section. See Figure 6 for k e y ...... 37

10 Mackellar measured section CPZ (Clarkson Peak) with arrows to illustrate small-scale coarsening-upward sequences. The thick sand body at 147-158 meters is interpreted as an abandoned delta lobe. See Figure 6 for k e y ...... 38

11 Mackellar measured section TGA (Tillite Glacier) showing large-scale coarsening-upward sequence, followed by delta lobe abandonment and return to quiet or deep water conditions. See Figure 6 for key . . . 39

12 Wavy and flaser bedding in delta front siltstones and sandstones from the Mackellar Formation, section TGA; Swiss army knife for scale . 42

13 Contour map showing the thickness of the basal shale in the Mackellar Formation. Thicker shale deposits are interpreted to indicate deeper water and increasing distance from s h o r e ...... 44

14 Contour map showing the total thickness of the Mackellar Formation, Beardmore Glacier region, A n ta rc tic a ...... 45

15 Summary of paleocurrent directions for the Permian Mackellar Formation in the Beardmore Glacier region, Antarctica. Diagram from Isbell (1990); data from Barrett (1968) and Miller and Frisch (1986) ...... 46

16 Summary of paleocurrent directions for the Permian Fairchild Formation in the Beardmore Glacier region, Antarctica. From Isbell (1990) . . 52

17 Rooted horizon within the Buckley Formation illustrates paleosol development. Arrows point to thin root traces within the siltstone bed. From Lamping Peak section LPP; Swiss army knife for scale . . . 56

18 Coal bed as cap to fining upward sequence in the Buckley Formation, section MAR. 1.5 meter bamboo pole for s c a le ...... 58

19 Summary of paleocurrent directions for the Permian lower Buckley Formation informal subunit in the Beardmore Glacier region, Antarctica. From Isbell (1990) ...... 59

xv 20 Summary of paleocurrent directions for the Permian upper Buckley Formation informal subunit in the Beardmore Glacier region, Antarctica. From Isbell (1 9 9 0 ) ...... 61

21 Correlation of vitrinite reflectance (Ro%) with other maturation indices. Vitrinite reflectance increases as thermal alteration increases. From Dow ( 1 9 7 7 ) ...... 66

22 Visual kerogen identification in the Permian portion of the Beacon Supergroup. The Pagoda, Mackellar and Buckley Formations are dominated by vitrinite and inertinite derived from terrestrial sources. The terms "amorphous" and "alganitic" kerogen are often used sy n o nym ou sly...... 77

23 Visual kerogen identification in the informal subunits of the Mackellar Formation. Amorphous (alganitic) kerogen is most abundant in the black shales of the "lower" Mackellar Formation ...... 78

24 Summary of data from the Permian portion of the Beacon Supergroup that compares vitrinite reflectance to proximity to sills. Vitrinite reflectance generally decreases with increasing distance from the sill, and becomes relatively uniform at greater than one sill thickness. There does not appear to be a difference in the effects of underlying and overlying s i l l s ...... 89

25 Mackellar Formation, in section CPZ illustrating the relatively constant nature of T.O.C. content in the Mackellar Formation when sills are not present. Exclusively sampling the fine-grained beds removes variability due to grain size or com position ...... 92

26 Mackellar Formation, in section TGA, illustrating the effect of an overlying sill on T.O.C. content. An overlying sill reduces the T.O.C. content toward the top of the section ...... 93

27 Mackellar Formation, in section MMC illustrating the effect of an underlying sill on T.O.C. content. An underlying sill reduces the T.O.C. content toward the bottom of the section. The combined effects of the lower and middle sills depress the T.O.C. content for up to 1.5 times the thickness of the lower sill. Multiple sills cause a cumulative alteration on the surrounding sediments that is greater than the sum of alteration caused by the two individual s i l l s ...... 94

xvi 28 Summary of Mackellar Formation data that compares T.O.C. content to proximity to a sill. Carbon content decreases rapidly at distances of less than one sill thickness. This criterion is used to identify altered vs. unaltered samples. There does not appear to be a signihcant difference between alteration by an underlying sill and alteration by an overlying sill. The effects of multiple sills are not considered in this diagram . 95

29 Mean T.O.C. content in the four Carboniferous/Permian formations from the Victoria Group. Carbon content and the associated organic productivity increased as the Late Paleozoic retreated . . . 101

30 Comparison of vitrinite reflectance vs. Si02 and K20. There is a lack of correlation between vitrinite reflectance values and the abundance of most major, minor, and rare-earth elements. Error bars for elemental abundances on this and succeeding graphs are displayed as a single horizontal line that is two standard deviations wide, and are obtained from five replicate runs of sample MTM 269.0 (Appendix B) . . . 130

31 Comparison of vitrinite reflectance vs. F e ^ and MgO values from selected stratigraphic sections. Sections MTR and MPI show a positive correlation between increasing alteration and increasing abundance of iron and magnesium. This implies that the intrusive body contributes iron and magnesium to the sediment ...... 131

32 Comparison of Si02 and KzO abundance vs. distance from intrusive bodies. There is a lack of correlation between the abundance of most elements and proximity to the intrusive body. The standard deviation for each element is plotted as a vertical bar two standard deviations in height, and standard deviations reported on the graphs are taken from five replicate analyses of sample MTM 269.0 (Appendix B) . . . . 134

33 Comparison of Fe203 and MgO abundance vs. distance from intrusive bodies. Sections MTR and MPI show a positive correlation between proximity to the sill and abundance of iron and magnesium .... 136

34 Comparison of Si02 and K20 abundance vs. total organic carbon content. Most elements have a negative correlation with organic carbon content, suggesting that organic carbon acts as a dilutant. Vertical bars on each graph indicate the standard deviation of the element analyzed, and are taken from five replicate runs of sample MTM 269.0 (Appendix B ) ...... 137

xvii 35 Comparison of Ni abundance vs. total organic carbon content. The weak correlation between nickel content and organic carbon abundance suggests that organic carbon does not control nickel distribution. The top diagram shows this relationship for all four formations, whereas the bottom diagram concentrates on the Buckley F o rm ation ...... 138

36 Comparison of A1203 and Fe203 abundance vs. Si02 content. The negative correlation is interpreted as a mineralogic and grain size effect, with A1203 and Fe203 carried by fine-grained clastic minerals . . . 142

37 Comparison of N a ^ and Hf abundance vs. Si02 content. The positive correlation is interpreted as a mineralogic and grain size effect, with NajO and Hf carried by coarser clastic m inerals...... 143

38 Comparison of MgO abundance vs. A1203 and Fe203 content. The positive correlation is interpreted as a mineralogic and grain size effect, since these elements are common in the fine-grained clay fraction. . 147

39 Comparison of NajO abundance vs. A1203 and F e ^ content. The negative correlation is interpreted as a mineralogic and grain size effect, with N a ^ carried by coarser clastic minerals ...... 148

40 Nesbitt and Young’s Chemical Index of Alteration increases in the southern part of the study area. This is interpreted as a weathering/climatic effect that developed on low relief floodplains 154

41 Geographic and stratigraphic variations in Al20/T i0 2 ratios. Lower Al20 / r i 0 2 ratios in the southern sections and higher Al20 / r i 0 2 ratios in the Buckley Formation are interpreted to represent changes in sediment supply ...... 157

42 Geographic and stratigraphic variations in SiOj/Al2Oj ratios reveal in increase in Si02/Al203 content in the Buckley Formation and are interpreted to represent changes in sediment supply ...... 161

43 Geographic and stratigraphic variations in K-jO/NajO ratios reveal an upsection increase in K20/Na20 content and a low initial K20/Na20 ratio in the southern part of the study area. These differences are interpreted to result from changes in sediment s u p p ly ...... 164

xviii 44 Geographic and stratigraphic variations in K20/CaO + NajO ratios reveal an upsection increase in KzO/CaO + NajO content and a low initial K20/CaO + N a ^ ratio in the southern part of the study area. These differences are interpreted to result from changes in sediment s u p p ly ...... 165

45 Results of cluster analysis using major element concentrations from Carboniferous/Permian mudrocks. Clusters two and three are dominated by samples from the Buckley Formation, while clusters five (and to a lesser extent cluster four) show a chemical distinction in the Mackellar Form ation ...... 169

46 Graphic representation of results obtained from principal component analysis of major elements and organic carbon. Principal component one (shown) describes an organic carbon component which dilutes the clastic influx in the Buckley Formation, and a major element association which is interpreted to represent detrital siliciclastic dominance in the lower u n i t s ...... 170

47 Graphic representation of results obtained from principal component analysis of major elements concentrations, normalized to account for high carbon contents. Principal component one (shown) describes a tectosilicate (SiOz) dominance in the Buckley Formation, and a phyllosilicate abundance (represented by MgO, Fe203, and Al203) in the lower u n i t s ...... 174

48 Graphic comparison of loadings on principal component one for data set which includes altered samples and data set with unaltered samples only. The close correlation between the two data sets confirms that there is little chemical difference between the altered and unaltered samples. The possible exception is F e^j, which may have been mobilized by the intrusion of diabase sills and d i k e s ...... 179

49 Chlorite and illite abundance patterns in the world oceans. Chlorite is a high latitude weathering product, derived from physical weathering of cratonic source material. Illite is a mid-latitude weathering product, derived from a combination of physical and chemical weathering. From Chamley (1989), after Lisitzin ( 1 9 7 2 ) ...... 193

xix 50 Kaolinite and smectite abundance patterns in the world oceans. Kaolinite is a low-latitude weathering product, formed by intense chemical weathering. Smectite is also a chemical weathering product, and tends to form in mid-latitudes near volcanic source areas. From Chamley (1989), after Lisitzin ( 1 9 7 2 ) ...... 194

51 Typical x-ray diffraction pattern from the Beardmore Glacier region, Antarctica, showing minerals present and peaks used for peak area measurements...... 208

52 Geographic distribution of relative quartz abundance values for the Mackellar Formation. All values from each locality are summed and presented as an average. Lack of regional patterns indicates that depositional processes associated with the Mackellar basin are not responsible for quartz distribution ...... 216

53 Geographic distribution of relative quartz / (feldspar + clay ) abundance values for the Mackellar Formation. All values from each locality are summed and presented as an average. Lack of regional patterns indicates that depositional processes associated with the Mackellar basin are not responsible for quartz, feldspar and clay distribution . . . 217

54 Relative abundances of quartz and illite are plotted to demonstrate mine ralogic differences between the four studied formations. The glacial Pagoda Formation has the highest relative quartz content, while quartz becomes proportionally more important in the Buckley Formation as the relative abundance of illite decreases from the Mackellar to the Fairchild and Buckley Formations ...... 219

55 Relative abundances of quartz and chlorite are plotted to demonstrate mineralogic differences between the four studied formations. The glacial Pagoda Formation has the highest relative quartz content, while quartz becomes proportionally more important in the Buckley Formation as the relative abundance of chlorite decreases from the Mackellar to the Fairchild and Buckley F o rm a tio n s ...... 220

56 Plot of vitrinite reflectance data (Ro) vs. illite crystallinity measurements for all available data. The random pattern indicates a lack of correlation for these two p a ra m e te rs ...... 224

57 Plot of vitrinite reflectance data (Ro) vs. illite crystallinity measurements for samples from section MBO. The random pattern indicates a lack of correlation for these two p a ra m e te rs ...... 225

xx 58 Examples of illite crystallinity measurement, as measured on bulk samples and randomly oriented x-ray mounts. Sample numbers and vitrinite reflectance values are listed for each sample. Peak width measurements on poorly formed peaks are subjective, and use of bulk samples introduces a range of grain sizes to the s a m p le ...... 227

59 Location of the study area and paleosol sections that were measured, collected and described during the 1990/1991 field season. (MAR denotes Mount Ackemar locality, GVA, GVB and GVC are Gordon localities, WLG denotes , and MKP is a measured section on Mount Kirkpatrick) ...... 233

60 Typical paleosol section from the Triassic in the Beardmore glacier region. Vertical roots appear to be more common in silty beds adjacent to the sandy channel deposits. This suggests that conditions of high sediment supply favored with rapid vertical gro w th ...... 234

61 SEM photograph of small-scale root development in Triassic paleosols. Vertical root at the top of the photograph (highlighted with dashed line) is 1 cm in diameter, mineralized, and perpendicular to bedding. Horizontal root hairs 0.1 to 0.3 mm in diameter project outward from the vertical root (see arrows), are carbonized, and lay parallel to the bedding surface ...... 236

62 Vitrinite reflectance vs. carbon-normalized abundances of representative major, trace and rare-earthelem ents ...... 303

63 Carbon-normalized abundances of representative major, trace and rare- earth elements vs. proximity to intrusive b o d ie s ...... 309

64 Abundances of representative major, trace and rare-earth elements vs. organic carbon content (note that elemental abundances are not carbon- normalized for this series of bivariate p l o t s ) ...... 315

65 Transition metal abundances vs. organic carbon content, with detailed analysis of the Buckley F o rm a tio n ...... 321

66 Carbon-normalized abundances of representative major, trace and rare- earth elements vs. normalized Si02 c o n t e n t ...... 327

67 Carbon-normalized abundances of representative major, trace and rare- earth elements vs. normalized A1203 c o n te n t ...... 333

xxi Carbon-normalized abundances of representative major, trace and rare earth elements vs. normalized FejOj c o n te n t ...... CHAPTER I

INTRODUCTION

Statement of purpose

Fine-grained Carboniferous(?)/ Permian and Triassic sediments from the

Beardmore Glacier region, Antarctica, are examined here to provide a better understanding of their field relations, depositional environments, chemical and mineralogic composition, paleoclimatic records and provenance history. These objectives are part of the long-term goal of interpreting the geology of the Beacon

Supergroup of Antarctica. The Antarctic continent is central to our understanding of ancient climatic conditions and earth history of Gondwanaland, and Permian time is important for several reasons. During Permian time, climatic evidence indicates a change from glacial to non-glacial conditions, and tectonic patterns along the

Pacific margin of Antarctica were different from present-day conditions. The following questions were considered in this project, and answers were sought through a combination of field data, geochemical and mineralogic analysis:

♦ What depositional environments are represented by Permian sediments,

and what processes were responsible for deposition of the sediments?

• What was the paleogeography of the Beardmore Glacier region during

1 Permian time? How long did the Beardmore Glacier region serve as

a basin that received detrital sediment, and what conditions were

responsible for paleogeographic changes?

• What was the source of detrital sediment supplied to the Beardmore

Glacier region during Permian time? Did source areas remain

constant during Permian time, and if not, what were the mechanisms

of change?

• Did a volcanic influx (described in other regions of Antarctica during

Permian time) affect the Beardmore Glacier region? If so, when, and

how was sediment supplied?

• What climatic conditions existed in the Beardmore Glacier region during

Permian time? Is evidence of the retreat of the Carboniferous(?)/

Permian ice sheet recorded in the sediments?

• How can organic geochemistry of the Permian sediments from the

Beardmore Glacier region be used to interpret climatic conditions or

sources for detrital sediment?

• Do the present-day mineralogy and geochemistry of Permian rocks from

the Beardmore Glacier region accurately reflect conditions at the time

of deposition? If so, how can mineralogy and geochemistry be used

to interpret ancient climatic and depositional conditions? If not, how

can mineralogy and geochemistry be used to examine the extent of

alteration? • How did Jurassic igneous intrusions affect the chemistry and mineralogy

of fine-grained Permian sediments in the Beardmore Glacier region?

What minerals or compounds were stable, and what minerals or

compounds were altered?

Antarctica is covered by a thick blanket of ice, but information provided by analysis of the sedimentology, geochemistry and mineralogy of a few well-exposed outcrops in the Beardmore Glacier region leads to interpretations about the depositional history and paleoclimate of a much larger area.

Rocks in the Beardmore Glacier region were chosen for a combination of field study and geochemical and mineralogic analyses because an unusual set of stratigraphic and physical conditions allows identification and evaluation of the controls on sediment composition. One of the most important characteristics of the study area is the extraordinary rock exposure in the Beardmore Glacier region.

Outcrops that are visible today in the Beardmore Glacier region are a result of

Mesozoic and Cenozoic uplift that placed sediments of the Beacon Supergroup above ice level in a broad series of well-exposed mountain belts. These outcrops extend laterally for several kilometers and vertically for hundreds of meters, allowing accurate identification of the units studied and precise positioning of individual sample localities.

Physical and chemical conditions are also unusual in the Beardmore Glacier region, because chemical weathering is minimal in the cold Antarctic climate. Cold temperatures and scarcity of modem biologic action contribute to the lack of chemical weathering and dominance by physical weathering processes. This lack of chemical weathering minimizes complications due to surficial weathering of recently exposed outcrops, and allows other controls on the chemistry and mineral composition to be identified. The Beardmore Glacier region is an ideal locality for interpreting the histories of paleoclimate and provenance from sediment composition. When these controls on the chemistry and mineral composition of fine-grained sediment have been identified, methods used in this study can be applied to other stratigraphic units or other areas.

In an effort to minimize chemical and mineralogic variability introduced by differences in grain size, samples were collected only from shales and siltstones, and only the finest grained beds from each measured section were sampled. At each locality were described, lateral and vertical relations within and between different lithologic units were noted, and sedimentary structures were recorded. Fresh samples were quarried from each sample locality to prevent contamination by float and to minimize surficial weathering effects. This field work served as the basis for interpretations about depositional environments, and samples collected during the field phase were used for geochemical and mineralogic analyses that provide the information used for interpretations of the paleoclimatic and provenance histories of the Beardmore Glacier region. 5 Study area

Field work for this project was conducted during the 1985-1986 and 1990-

1991 Held seasons, from remote base camps established on the Bowden Ndvd in the

Beardmore Glacier region of the Central Transantarctic Mountains. The study area encompasses approximately 90,000 km2 in an area of glacier-filled valleys and rugged mountain peaks. Twenty-four sections from 21 localities were described and measured, and 310 samples were collected for chemical and mineralogic analysis (Homer and Krissek, 1989; Krissek and Homer, 1988a; Krissek and

Homer, 1988b). These sections total 3,789 m in thickness, and provide a representative geographic and stratigraphic sampling of variations within this part of the Permian depositional basin (Figure 1).

Previous work

Earlier workers identified many of the best outcrops in the Beardmore

Glacier region, and these localities were revisited whenever possible to provide a link with previous studies. Detailed sedimentologic and petrographic work by

Barrett (1968), Barrett and others (1986), Frisch (1987), Isbell (1990), Lindsay

(1968), Lord (1986), Miller (1989) and Waugh (1988) focused attention on sedimentary relations in the Beardmore Glacier region, and served as the starting point for much of this study. Section designations differ between the various authors, although in several cases the same stratigraphic sections were visited and described by different research groups. Stratigraphic sections from this study that 6

A ntarctica

Figure 1: Location of study area and measured stratigraphic sections in the Beardmore Glacier region, Antarctica. 7 were also described by other workers are tabulated in Table 1. Previous work that relates to the basement geology or early stratigraphic designations in the Beardmore

Glacier region is summarized in the following section. The discussion of basement geology is followed by a summary of the stratigraphy of Carboniferous(?)/Permian to Lower Triassic sediments of the Victoria Group, which are the main focus of this study.

Pre-Permian geologic history of the Beardmore Glacier region

One of the major goals of this project is to examine the provenance history

(place and conditions of origin) of the detrital particles that combined to form the fine-grained Permian sediments. Provenance is important to sedimentary geologists because information about the pre-depositional history of a sedimentary rock can be obtained from the individual grains. Detrital grains provide information about the composition of the source area, weathering conditions, modes of transport and post- depositional alteration. Composition of the parent material is commonly the single most important factor in determining the composition of detrital sedimentary rocks, so provenance studies are important in determining the geologic history of an area.

Provenance studies are especially important in Antarctica, where the sub­ ice basement geology is poorly known. In the Beardmore Glacier region, basement rocks are one likely source for the detrital clastic material that forms the sediments of the Victoria Group. For these reasons, the basement geology and pre-

Carboniferous history of the Beardmore Glacier region are summarized below, with 8 Table 1: Comparison of stratigraphic sections and section names described by previous workers in the Beardmore Glacier region, Antarctica.

Section location Barrett Lindsay Frisch Waugh Isbell (Homer) (19

MTR Mount Ropar Ro MR1 MAR Mount Achernar: MA6=lower section MA6 MA5=middle section MA5 MA6=upper section MA4 LPP Lamping Peak MBO Mount Bowers: MBO=lower section Bo MBU=upper section MB CHI Cherry Icefall

MDK Mount Deakin MDK 9 the ultimate objective of identifying types of pre-Carboniferous rocks that may have served as sources for sediment supplied to the Victoria Group. The Permian paleogeography of the Beardmore Glacier region is poorly known, so discussions of source areas are limited to general statements about basement rock lithologies that are consistent with the observed chemical or mineralogic distribution in Permian sediments. It is not possible to pin-point the exact source area for many of these sediments, and the possibility that other, unknown sources existed cannot be excluded. These unknown sources may lie beneath the present-day ice sheet, they may be part of other continents, or they may have existed in Permian time, but are not necessarily present today.

Much of Antarctica is covered by ice, but outcrops in the Transantarctic

Mountains expose basement material that reveals a complex orogenic history.

According to an early estimate by Elliot (1975a), 60-70% of the exposed metamorphic rocks of the are metamorphosed basic or intermediate volcanic rocks. An additional 20-25% are metamorphosed mudstones, and 5-10% are metamorphosed carbonates. More recent estimates of the composition of the shield indicate that it is composed of a high proportion of granite gneiss (David Elliot, personal communication). At least three orogenic episodes are recorded by basement rocks in the Transantarctic Mountains, and these events and the associated lithologic assemblages are discussed below. A map of the basement geology in the Beardmore Glacier region (from Gunner, 1983) is provided for reference (Figure 2). MILLER lxi

RANGE/ LU

l±J h*

MT HOPE COAL5ACKBLUFF

BUCKLEV

•Cb- 50

LEGEND

| 1 Beacon Supergroup(B) to Ju rassic Granite Harbour LZ3 Intrusives

Byrd Group (-CB) Upper Precambrian E to

Beardmore Group Precambrian Nimrod Group

Figure 2: Map of basement geology in the Beardmore Glacier region, Antarctica From Gunner, 1983. 11 Basement geology

In the Beardmore Glacier region, several major tectonic events preceded deposition of the Victoria Group. The oldest recognizable stratigraphic sequence is the Precambrian Nimrod Group (Grindley and McDougall, 1969), a folded and tectonized sequence of schist, paragneiss, metavolcanics, marble and dolomite with some orthogneiss. These rocks have been described and dated by many workers

(Grindley, 1972; Gunner and Faure, 1972; Adams and others, 1982; Gunner, 1983;

Borg and DePaolo, 1990; Borg and others, 1989; Borg and others, 1990; Goodge and others, 1990; Goodge and others, 1991). Metamorphosed gneiss and schist of the Nimrod Group are presently exposed in the Geologists Range and the Miller

Range (Stump, 1992), regions that lie to the northwest of the Queen Elizabeth

Range in the central Transantarctic Mountains (Figure 2). These geographic regions probably served as source areas during deposition of Permian sediments

(see Chapter II), so the Nimrod Group is a potential supplier of detrital sediment to the younger Permian units.

Deposition and subsequent orogenic deformation of the Upper Precambrian

Beardmore Group is the next recognizable event in the central Transantarctic

Mountains (Stump, 1992). The Beardmore Group is divided into the Cobham

Formation (Laird and others, 1971) and Goldie Formations (Gunn and Walcott,

1962), although outcrops of the Cobham Formation are limited to a small exposure in the Cobham Range (to the north of the ). The Cobham

Formation is the older of the two, and is composed of quartzite, marble and schist 12 that overlie older metasediments and metavolcanics of the Nimrod Group (Laird and Bradshaw, 1982). The Goldie Formation overlies the Cobham Formation

(Laird and others, 1971), and consists of a thick sequence of metamorphosed shale and silty sandstone with minor diamictite (Stump and others, 1988) that is exposed in the Nimrod Glacier region and the northwest part of the Queen Elizabeth Range

(Figure 2). Sediments of the Goldie Formation are metamorphosed to gieenschist facies or higher, and in the Miller Range, the Goldie Formation is composed of high-grade gamet-plagioclase gneisses, garnet-bearing amphibolites, marble and quartzite (Grindley, 1963). Metasediments from the Goldie Formation lack the abundant rock fragments that are common in the underlying Nimrod Group, and are interpreted to have been deposited by quartzose turbidity flows and in shallow water carbonate basins (Stump, 1992). The resulting metasediments may be representative of basement material that served as a source for detrital sediment during deposition of the Beacon Supergroup.

Following the Beardmore Orogeny, sediments of the Cambrian Byrd Group were deposited along the paleo-Pacific margin of Antarctica. The Byrd Group was named by Laird (1963) to describe a thick series of metasediments that lie unconformably on older Precambrian and Cambrian metagraywackes. In the

Beardmore Glacier region, the Byrd Group is divided into the Shackleton

Limestone (Grindley, 1963) and the Starshot Formation (Laird, 1963). The

Shackleton is composed of conglomerate and quartzite beds at its base, and grades upward into a thick, Archaeocyathid-bearing carbonate sequence (Laird and Waterhouse, 1962; Laird and Bradshaw, 1982; Gunner, 1983; Rees and others,

1988; Rees and others, 1989; Rowell and others, 1990; Rowell and others, 1992).

The Starshot Formation overlies the Shackleton Limestone, and consists of coarse­ grained elastics, arkosic and calcareous sandstone and locally abundant carbonate clasts (Adams and others, 1982). Sediments of the Byrd Group were intruded, metamorphosed and folded during the Ross Orogeny (Borg and others, 1989; Borg and others, 1990). In the central Transantarctic Mountains, these intrusives are referred to as the Hope Granite and Granite Harbour intrusives (Gunner, 1983; Borg and others, 1989).

Beacon Supergroup

Following the Ross Orogeny, clastic sediments that belong to the Beacon

Supergroup were deposited along the paleo-Pacific margin of Antarctica. The lowermost Beacon sediments belong to the Taylor Group, and were not included in the field study or chemical and mineralogic analyses that form the bulk of this dissertation. A brief synopsis of the Taylor Group is included here, since Taylor

Group sediments are important in provenance studies of the younger Beacon units.

Sandstones of the Taylor Group were deposited on the Kukri Erosional

Surface (Bradshaw, 1991), a broad peneplain that records a period of widespread erosion prior to deposition of Beacon sediments. In the Beardmore Glacier region,

Taylor Group sandstones were named the Alexandra Formation by Grindley (1963).

At the type section in the Queen Alexandra Mountains, the Alexandra Formation 14 includes over 1,000 meters of cross-bedded quartz sandstone that lie unconformably on metamorphosed basement graywacke (Grindley, 1963). Body have not been found in the Alexandra Formation, although similar deposits in the McMurdo

Sound region have yielded non-marine fish fossils, spores and lycopod remains that all indicate a Devonian age for the unit (Grindley, 1963).

In the Central Transantarctic Mountains, Devonian sediments are truncated by a broad erosional surface with low relief. This unconformity is called the Maya erosional surface, and is cut on granitic or metamorphic basement material or

Devonian(?) sandstone of the Alexandra Formation (Coates, 1985). Erosional truncation of the Alexandra Formation may be attributed to Carboniferous/Permian glaciation, an event that blanketed the southern continents in a thick sheet of ice

(Frakes and others, 1971). This study focuses on the glacial unit deposited by this ice sheet and on the post-glacial sediments of Permian and Early Triassic age that record the transition from glacial to non-glacial conditions. Depositional environments of these units are described in detail in Chapter n (Sedimentology).

A summary of the stratigraphy of these units is given below.

Carboniferous(?)/Permian to Lower Triassic Stratigraphy

The units studied in this project are the Carboniferous(?)/ Permian Pagoda

Formation, Permian Mackellar, Fairchild and Buckley Formations, and the Triassic

Fremouw Formation (Figure 3). These units belong to the Beacon Supergroup, and together with the Falla Formation and Prebble Formation (which were not examined 15

u CO Prebble Formation

Falla Formation o s Fremouw Formation S

Buckley Formation §• Fairchild Formation Permian

Victoria Group Victoria Mackellar Formation CO

3 2 § £ Pagoda Formation n

Alexandra Formation Devonian? Taylor Group Taylor

Figure 3: Stratigraphy of Carboniferous(?) to Lower Jurassic sediments in the Beardmore Glacier region, Antarctica. The Pagoda, Mackellar, Fairchild, Buckley and Fremouw Formations are examined in this study. 16 in this study), form the Victoria Group (Figure 3). Carboniferousf?)/ Permian-

Triassic elastics from the Beardmore Glacier region are part of an outcrop belt that extends for more than 1000 km along the paleo-Pacific margin of .

A time-space diagram by Isbell (1990) illustrates the lithologic similarity of

Permian sediments from the to the Allan Hills (Figure 4). Locations of these outcrops in the Transantarctic Mountains are summarized in Figure 5 (from

Isbell (1990), and modified from Elliot (1975a)).

The basal Carboniferous(?)/Permian unit in the Beardmore Glacier region is the glacially deposited Pagoda Formation. Pagoda tillites have been correlated with

Stage 1 (upper Carboniferousf?)) palynomorph zones of (Farabee and others, 1990a), although this is accomplished by lithostratigraphic correlation rather than by biostratigraphic correlation based on samples from the Beardmore Glacier region. A more conservative (and widely accepted) correlation scheme from Kyle and Schopf (1982) places the Pagoda Formation as a lithostratigraphic equivalent of

Antarctic tillites with known Stage II affinities. Lateral correlation of the Pagoda

Formation to equivalent units is summarized by Barrett and others (1986), and a description of the Permian glacial sequence from the central Transantarctic

Mountains to the Wisconsin Range is given by Coates (1985).

Thickness patterns in the Pagoda Formation are controlled locally by basement topography (Isbell, 1990), although larger-scale regional patterns suggest the existence of a depositional basin that extended along the paleo-Pacific margin of Antarctica. This basin is referred to as the CTM (Central Transantarctic 17

£ ifl <71 u 2 ■C C 3 u ■5 iv j i <0 e • QC Ifl £ 5 w C c £ 3 X IQ V 3 c> o c IA 10 ^5 3 V o ■J 0 5 “ m o 3 2 a < e C 3 ■o c c X 3 e .* = » e * o C5 3 j 3 « 6 C _ i y c J i 0 v* ■u V 1) E * (0 3 3 >> <5 V 5 i/i z to a O Z CD a OD <

Lowtr - Triassic iAy y * -l i 0 III" 200

265

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PALEOCURRENTS | diamictite IV V V V voicamdastic «— parallel to cage 1 v v v s anastone I"— --“-I shale coal I i trend oarailel ' ' to quarts —laid, m | ss. body © toerarda viewer sanostona

conglomerate erosion surface Q away from viewer

Figure 4: Time-space diagram from Isbell (1990) shows the lithologic similarity of Permian sediments in the Transantarctic Mountains. 18

85°S

% Q % A, % 85° S Paoon Escarpment Thiel Mtns. -{— 90°W

ML Weaver

O h Range Nikon Plateau Wisoonsm Range — y 1 Dominton Range Scott Gl. Buckley Island Queen Alexandra Range Axe/ Heiberg GL Queen Elizabeth Range Shackleton GL J Ramsey GL Geologists Range Beardmore Gf. Nimrod GL- Ml Hunt Starshot GL- Byrd GL. Darwin Mountains Darwin GL- Mukjck Gl.- , —Ml Ritchie ‘ —Ml. Meticnei SVL - - v Mt, Fleming M/-" . —Carapace Nunatak —Allan Hills Mackay GL ^ —Prince Albert Mtns. David GL Priestley GL Victoria Land 75°S

Ross Sea Freyberg Mtns.

Ham Bhrtf

180° RenrUck GL __I_

Figure 5: Map from Isbell (1990), originally modified from Elliot (1975a), illustrates geographic locations along the Transantarctic Mountains. 19 Mountain) basin by Collinson (1990), and served as a broad trough where glacial sediments were deposited and preserved along the Pacific margin of Antarctica. At the southeastern end of the CTM basin, a structural high called the Ross High

(Collinson, 1990) may have isolated Victoria Land from the Transantarctic basin.

The Mackellar Formation is a basinal to deltaic deposit that contains black shales, and has correlative exposures that have been studied from the Queen

Elizabeth Range to the Ellsworth Mountains (Barrett and others, 1986; Miller and

Frisch, 1987; Isbell, 1990; Collinson, 1990; and Collinson, 1991). Body fossils have not been found in the Mackellar Formation, although a poorly preserved palynomorph assemblage allows correlation of the Mackellar Formation with Upper

Carboniferous(?)/ Lower Permian sediments from Australia (Farabee and others,

1990a). Lithostratigraphic correlation by Kyle and Shopf (1982) agrees with this general age determination. The post-glacial black shale sequence is a lithologic package that is also found in the Parana Basin of and the Karoo

Basin of (Oelofsen, 1987), and is interpreted to represent the same widespread post-glacial deposition.

On a regional scale, thickness patterns, geochemical characteristics and provenance of Mackellar equivalents change from the Ellsworth Mountains to the

Beardmore Glacier region. Mackellar equivalents are thickest and have marine trace fossils and a volcanic arc provenance in the Ellsworth Mountains (Collinson and Miller, 1990). The nature of the black shale changes in the direction of the central Transantarctic Mountains, becoming thinner with non-marine affinities and a 20 continental provenance in the Beardmore Glacier region (Miller and Frisch, 1987;

Miller and others, 1987). The paleogeographic setting of Mackellar deposition is interpreted as an elongate marine to brackish embayment along the paleo-Pacific margin of Antarctica, with deposition centered in the CTM Basin of Collinson

(1990). Mackellar equivalents thin and finally pinch out in the Queen Elizabeth

Range and Nimrod Glacier region, probably as a result of the continued presence of the Ross structural high.

The Fairchild Formation is a sandy braided stream unit that was defined in the Beardmore Glacier region (Barrett, 1969), because it lacked the distinctive

Glossopteris-bearing coaly beds of the overlying Buckley Formation. Fairchild sediments are probably contemporaneous with Buckley equivalents in other areas, but this unit has not been formally defined in many other regions. Kyle and Schopf

(1982) correlated Fairchild sediments, and place the lower Mount Glossopteris

Formation (Ohio Range), Amundsen Formation (Nilsen Plateau) and Weller Coal

Measures (South Victoria Land) as lateral equivalents of the Fairchild Formation.

Barrett and others (1986) continued this lithostratigraphic correlation by summarizing field descriptions from several other authors, and suggest that

Fairchild equivalents are found in the area, the Scott Glacier area and as far east as the Ohio Range. Fairchild sediments do not contain body fossils or identifiable palynomorphs, but have been correlated with Permian units of known Stage 3 and Stage 4 affinities (Farabee and others, 1990b). 21 The Buckley Formation is a braided stream deposit that contains coaly interbeds, and is correlative with units along the paleo-Pacific margin of Antarctica from the Ohio Range to Northern Victoria Land. Equivalent sediments are the

Pecora Formation (Pensacola Mountains), Mount Glossopteris Formation (Ohio

Range), Queen Maud Formation (Scott Glacier), Misthound Coal Measures (Darwin

Glacier) and Weller Coal Measures (South Victoria Land). These lateral equivalents of the Buckley Formation have been summarized by Barrett (1968),

Barrett and others (1986) and Isbell (1990). The Glossopteris-bearing coal measures of these units are diagnostic, and analysis of the rich palynomorph fauna places a Stage 4 (Early Permian) age on the upper Weller Coal Measures, and a

Stage 5 (Late Permian) age on the Mount Glossopteris and Queen Maud Formations

(Kyle and Schopf, 1982). Highly altered palynomorphs from Mt. Achemar in the

Beardmore Glacier region indicate a Stage 5 (Late Permian) age for the Buckley

Formation (Farabee and others, 1990b). Stratigraphic summaries of the Buckley

Formation and equivalent units are provided by Kyle and Schopf (1982), Barrett and others (1986), Farabee and others (1990a), Collinson (1990) and Isbell (1990).

On a regional scale, stratigraphic and sedimentologic relations in the

Buckley Formation and equivalent units provide details about the infilling of the

CTM Basin. Paleocurrents in the lower Buckley Formation and the older Victoria

Group sediments (described above) consistently point toward the Ohio Range

(southeast). These lower and upper Permian sediments in the CTM basin were separated from Victoria Land by the Ross High, a prominent structural divide. A 22 paleocurrent reversal during deposition of the Buckley Formation documents a change in the morphology of the CTM Basin, with paleocurrent directions that trend toward Victoria Land (northwest) for the remainder of Permian and Triassic time (Barrett, 1968; Barrett and others, 1986; Isbell, 1990). Infilling of the CTM

Basin and reversal of paleocurrent directions coincides with an influx of calc- alkaline volcaniclastic debris from an unknown source (Collinson, 1991). These events are all related to tectonic evolution of the paleo-Pacific margin of Antarctica, and are interpreted as recording the initiation of subduction and development of a foreland basin complex during Permian time (Collinson, 1990).

The Fremouw Formation is a sandy braided stream deposit that has equivalent exposures along the Transantarctic Mountains from the Nilsen Plateau to

North Victoria Land. Lateral equivalents include the Feather Conglomerate and the

Lashly Formation in South Victoria Land (Kyle and Schopf, 1982) and the Ellis

Formation (Darwin Glacier). Palynomorphs recovered from the Fremouw

Formation correlate with subzone C of the Australian Triassic palynologic zones

(Kyle and Schopf, 1982) and indicate an Early to age for these sediments. This correlation and age determination is supported by Farabee and others (1990a) who studied well-preserved palynomorphs from peat rafts in the

Fremouw Formation. An abundant fauna in the Fremouw Formation and its equivalent units is consistent with this interpretation, although Dicroidium is not considered to be a good index by biostratigraphers. Stratigraphic summaries of Triassic sequences in the Transantarctic Mountains have been 23 provided by Kyle and Schopf (1982), Barrett and others (1986) and Collinson

(1990; 1991).

Regional stratigraphic relations and petrography of Triassic sediments indicate continued influx of volcaniclastic rock fragments and evidence of airfall tuff during deposition of the Fremouw Formation (Barrett and others, 1986; Isbell,

1990). Paleocurrents in the central Transantarctic Mountains continue to trend toward Victoria Land (Barrett and others, 1986) and the Ross High was buried under a wedge of volcaniclastic sediment during Middle Triassic time, ending the structural isolation of the Victoria sub-basin (Collinson, 1991). Interpretation of these data using a foreland basin model suggests cratonward migration of a clastic wedge that was derived from a volcanic arc setting, and progressive infilling of the axial trough that served as a depocenter for Permian and Triassic sediments along the paleo-Pacific margin of Antarctica (Collinson, 1990; 1991).

Present-dav ohvsioeraphv of the Transantarctic Mountains

The events described above have created a complex Proterozoic to lower

Jurassic sequence of metasedimentary, metavolcanic and sedimentary rocks. Some of these events involved early episodes of compression and mountain building, but it is important to understand that the present-day physiography of the Transantarctic

Mountains is a result of more recent tectonic activity. Sediments of the Beacon

Supergroup were deposited when subsidence in a marginal basin allowed the preservation of terrestrial clastic detritus. Continued subsidence and burial of these 24 sediments preserved the sequence, and the thickness of overlying strata suggests a

maximum burial of over 2500 m for the base of the Beacon sediments. Apatite

fission track work by Fitzgerald and others (1986) indicates that rapid uplift and

block faulting associated with uplift of the Transantarctic Mountains may have

started at about 50 m.a., with an average uplift rate of approximately 100 m per

million years (Stump and Fitzgerald, 1992).

Interpretation of these data in a regional context has resulted in different

theories concerning the formation of the Transantarctic Mountains. Work by

Fitzgerald and others (1986) describes thickening, crustal underplating and uplift in

south Victoria Land, and extension and subsidence in the region. In this

model, uplift in the central Transantarctic Mountains has occurred as a result of

extensional forces that cause vertical crustal movement and step-faulting along the

Transantarctic Mountain (Fitzgerald and others, 1986).

A different regional tectonic model proposed by Stem and ten Brink (1989)

emphasizes the tensional (extensional) nature of the Transantarctic Mountains, and

uses crustal flexure and isostatic compensation as mechanisms for uplift of rigid east Antarctic crust and formation of the Transantarctic Mountains. This study employs crustal rigidity, gravity anomolies and heat flow data to describe the geologic differences between the Wilkes Basin, Ross Embayment, and East

Antarctic craton. The result is a comprehensive model that uses heat flow differences to explain the rapid uplift of the present-day Transantarctic Mountains. CHAPTER II

SEDIMENTOLOGY

Much of the information in this chapter was published previously in the

1991 American Geophysical Union Contributions to Antarctic Research n,

Antarctic Research Series, volume 53, p. 33-65. The portion of that paper that discusses the sedimentology of Permian sediments from the Beardmore Glacier area is presented here with minor additions.

Introduction

This chapter summarizes the sedimentology and interpreted depositional environments of the Pagoda, Mackellar, Fairchild and Buckley Formations.

Sedimentary structures, field relations, lithologic associations and paleocurrents that support these interpretations are discussed below. Much of the information presented in this section is an introduction to the sedimentology that relies heavily on the interpretations of previous workers, and is not intended to supplant these earlier studies. Previous interpretations of depositional environments are used as a starting point for detailed analyses of the paleoenvironment, paleoclimate and provenance that are included in later chapters of this study. Interpretations of

25 26 depositional environments that are presented in this section generally agree with the conclusions of other researchers (Grindley, 1963; Barrett, 1968; Lindsay, 1968;

Barrett and others, 1986; Miller and others, 1987; Miller, 1989; Isbell, 1990), and supplement these previous studies with additional field observations and selective laboratory investigation of the fine-grained facies. Depositional environments and lithologic associations of the Fremouw Formation will be discussed in Chapter VI

(paleosols).

Pagoda Formation

The Pagoda Formation is interpreted as a glacial deposit (Grindley, 1963; Lindsay,

1968, 1970; Waugh, 1988; Miller, 1989) that formed during the Carboniferous/

Permian glaciation of the Antarctic continent. Lithologies within the Pagoda

Formation are highly variable, with most measured sections composed predominantly of massive diamictite and lesser amounts of sandstone, siltstone and shale. Rare carbonate concretions in the Pagoda Formation have been analyzed for lsO, 13C and Si^/Sr86 isotopic compositions in an attempt to provide additional information about source areas and environmental conditions during the deposition of the Pagoda Formation and overlying units (Lord, 1986; Lord and others, 1988).

The average composition of the Pagoda Formation (as measured in this study) is shown in Table 2.

For future comparisons of chemical and mineralogical data, the Pagoda

Formation is divided into two informal subunits. These subunits do not have any Table 2: Lithologic summary of the Pagoda Formation, Beardmore Glacier region, Antarctica.

Lithology Section Shale Siltstone Sandstone Diamictite

MMF - 1.5 m 4.0 m 69.5 m

MMC - - - 17.6 m CPZ 36.5 m 43.0 m - 30.5 m MTM 20.5 m 10.0 m 10.0 m 74.3 m

TGA - 4.0 m 22.0 m 113.2 m CHI - 14.6 m 44.8 m 6.0 m

mo - -- 18.5 m Totals: 57.0 m 73.1 m 80.8 m 329.6 m Percentages: 10% 14% 15% 61% 28 lithologic connotations, and are based entirely on position in the measured sections.

A sample that lies in the lower half of the Pagoda Formation according to a

measured Pagoda section is referred to as a lower Pagoda sample (LP), and a

sample that is from the upper half of the Pagoda Formation according to a

measured Pagoda section is referred to as an upper Pagoda (UP) sample. These

designations are present on sample identification lists and summaries of chemical

and mineralogical data.

Three stratigraphic sections are used to illustrate the extremes of

composition within the Pagoda Formation. Section MMP (Figure 6) is a typical

diamictite-rich section. Sedimentary structures and depositional environments of

the diamictite have been described by Lindsay (1968), Waugh (1988) and Miller

(1989). Diamictite from the Pagoda Formation is gray-green, poorly sorted and

massive or sheared, and contains clasts of granite, quartzite, chert and metasediment

in a matrix of clay, silt and poorly sorted sand grains. The sand component is

quartz-rich and is interpreted to have been derived from the underlying Alexandra

Formation, whereas the granite and metamorphic clasts originate from an unknown

basement source. Source areas for detrital, chemical and mineralogic components

of the Pagoda Formation include the Antarctic continent and any other southern

landmass that the ice sheet scraped over before deposition of the Pagoda sediments, and may extend far beyond the drainage area encompassed by the Permian

depositional basin. Analysis of these glacial sediments is one of the few available methods of analyzing basement material that presently lies beneath the Antarctic ice 29 Section MMP /

Dolorite sill: 75 meters thick 80 Stltatone: Black, baked wv >f r.D#r^h'*rnLinrw i Boulders up to 60 cm. common 70 - x m m a sm a m m m In dlamlctlta aBSEammsagE Ola ml ct It* wtth aandatona Intarbeds: 60 - Sandstone bada 50 cm. thick Cleats rare 50 - Diamictite: Sandy, horizontally baddad Dlamlctlta: Inclined bedding, (sheared) contorted sandstone pods 40 - Dlamlctlta: Gray-green, sandy m Sandstone: Poorly to moderately 30 - sorted, high angle crossbeds Convolute sandstone pods In diamictite 20 - Diamictite: Gray-green, <5% pebbles and cobbles 10 - Conglomerate: Pebble to cobble lag deposit 0 . Dlamlctlta: Massive, mlcaoeous Ico cover

Key: ■ sandstone pods e deformed sandstone pods b sott-aedlment deformation r r r r = crossbeds m v a ripple marks • ass m dlagenetlc concretions

Figure 6: Diamictite-dominated measured section from the Pagoda Formation, Moore Mountains section MMP. Diamictites are an end-member in the range of glacial deposits, and indicate ice advance or retreat 30 sheet. Examination of individual beds of diamictite reveals that they can be

structureless, slumped, or interfingered with sandstone pods. The diamictites are

interpreted as basal debris (ground ) that was deposited by moving ice

(Lindsay, 1968). Miller (1989) also discussed ice movement, and distinguished

diamictite deposited by advancing ice from finer-grained units deposited during ice

retreat.

Sandstone is less common than diamictite in most Pagoda sections, but is

the dominant in section CHI (Figure 7). Sandstones are fine to medium

grained, vary from well sorted to poorly sorted (gradational to diamictite), and form

lenticular, pod-shaped or planar bodies. Sedimentary structures in the sandstone

beds include trough cross bedding, ripple marks, and soft-sediment deformation in

the form of contorted bedding. Sandstone bodies most commonly occur as lenses

tens of meters wide, with erosional lower boundaries and internal cross bedding.

Smaller pods of sandstone are also very abundant, and range from several

centimeters to two meters in width. These sandstone pods interfinger laterally with

diamictite or siltstone deposits. Planar sandstone beds are present but rare, and formed under the influence of high velocity flow that may have included migrating sand waves within pro-glacial streams. The combination of sedimentary structures and the lithologic association with nearby diamictite indicates that these sandstone bodies were deposited by subglacial meltwater or fluvial outwash streams (Lindsay,

1968; Waugh, 1988; Miller, 1989). 31 Section CHI

130 - Mackellar/Pagoda contact SI It stone Intertlngers wtth sandstone pods Quartz pebbles 120 - Scree cover Sandstone: Very poorly sorted, rippled 110 . Scree cover Slltstone: Poorly sorted, rippled Quartz pebbles 100 - Slltstone and sandstone httetllnger Sandstone: Well sorted, rippled 90 . Slltstone: Poorly sorted Sandstone: Moderately well sorted, 80 - slightly rippled, rare quartz pebbles Dlamlctlta: Massive, sandstone 70 - pods, sandstone clasts Scree cover 60 . Sandstone: Moderately well sorted, trough cross beds 50 - Sandstone: Crossbeds, sott sediment slumping 40 -

Sandstone: Moderately well sorted, 30 - trough crossbeds, quartz pebbles

20 - ScrM cover

10 -

0 - Ice cover

Figure 7: Sandstone-dominated measured section from the Pagoda Formation, Cherry Icefall section CHI. Sandstones are an end-member in the spectrum of glacial deposits and indicate deposition by moving water. See Figure 6 for key. 32 The Pagoda Formation at section CPZ contains abundant fine-grained material (Figure 8). Fine-grained Pagoda sediments occur as shale, silty shale and poorly sorted sandy mudstone. Shale and silty shale are rare in most sections, but form significant proportions of sections CPZ, MTM and CHI. Siltstones within these sections contain ripple marks, slump structures, flaser bedding and wavy bedding. These sedimentary structures indicate rapid deposition in a system with an abundant sediment supply. Fine-grained deposits are interpreted to have formed close to the ice margin in ponds or small lakes (Lindsay, 1968; Waugh, 1988;

Miller, 1989). The scarcity of dropstones in these quiet water deposits suggests that icebergs were rare. These environments where deposition occurred in standing water were probably more common during glacial retreats than during glacial advances, because glacial retreats were the time of maximum meltwater production, which enhanced formation of small pro-glacial lakes. In contrast, glacial advances blanketed much of the study area with ice, and cooler temperatures during these advances reduced the supply of meltwater. Preservation of standing water deposits was also favored during glacial retreats, because continued basin subsidence moved sediments below the base level prior to the next ice advance (Miller, 1989). The 30 m thick shale sequence exposed at Section CPZ confirms that the ice sheet was unstable and that retreat episodes occasionally persisted during deposition of the

Pagoda Formation. Coarser grained diamictite deposits that represent glacial advance cycles are not observed in the lower portion of this particular section. 33 Section CPZ

I / I / \ $ f \ 120 _ I Mackellar/Pagoda contact Diamictite: Gray-green, poorly aortad 110 - Scraa covar

100 - Dlamlctlta: Gray-green, abundant eoaraa quartz grains, rara chart and granite pebbles 90 - Sena cover 80 - Slltstone: Dark gray, micaceous 80% slltstone, 10% fine-grained sandstone Interbeds 70 - 70% slltstone, 30% aandstone

60 . Interbsdded sandstone and slttstona, aandstone beds are 20-40 cm. thick

50 - Interbedded slltstone and ahala Shale: Lenticular and wavy bedded 40 - Rippled slltstone

30 - Shale: Dark gray, recrystallized, trace lenticular bedding,

20 - Dlamlctlta: Poorly sorted, quartz pebbles 10 - Scree cover Shale: Dark gray, rate silty Interbeds

0 - Scrse covar

Dolerlte sill (17S meters thick)

Figure 8: Pagoda measured section illustrating the fine-grained end-member in the range of glacial deposits, Clarkson Peak section CPZ. Fine-grained sediments indicate deposition in pro-glacial ponds. See Figure 6 for key. 34 Pagoda depositional environments can be summarized as glacial, although the variety of lithologies present leads to more complex interpretations. Diamictites in the Pagoda Formation represent deposition by moving ice, sandstones are outwash deposits, and siltstones and shales represent deposition in quiet melt-water ponds or glacio-fluvial environments. Although diamictite is the most abundant lithology, sandstone, siltstone and shale are important for detailed interpretations and may be volumetrically important in specific sections.

Mackellar Formation

The Mackellar Formation is composed of fine- to medium-grained elastics that are interpreted to record the rapid post-glacial infilling of a basin (Barrett and others, 1986; Frisch, 1987; Miller and others, 1987). Isostatic depression as a result of loading by the Carboniferous(?)/ Permian ice sheet may have been a factor in the initial subsidence of this basin. Observations made during the 1985/86 field season support the interpretations of previous workers, and are summarized here.

Dominant lithologies in the Mackellar Formation are sandstone, siltstone and shale, and the relative proportions of each lithology in the thirteen measured sections are shown in Table 3. Rare carbonate concretions and very rare thin carbonate beds are also found in the Mackellar Formation, and these carbonates have been analyzed for I80, l3C and Sr^/Si86 isotopic compositions in an attempt to provide additional information about source areas and environmental conditions during the deposition of the Mackellar Formation (Lord, 1986; Lord and others, 1988). Table 3: Lithologic summary of the Mackellar Formation, Beardmore Glacier region, Antarctica.

Lithology Section Shale Siltsione Sandstone MKR 4.7 m 21.4 m 46.7 m MMQ 6.0 m 26.7 m 27.3 m MMA 11.5 m 39.4 m 22.4 m MMC 27.8 m 26.0 m 42.9 m MMD 26.8 m 12.8 m 66.4 m TRM 11.5 m 12.8 m 36.7 m CPZ 22.3 m 26.2 m 22.1 m MTM 8.3 m 41.7 m 30.4 m TGA 21.9 m 18.1 m 37.0 m MBO 22.6 m 32.6 m 44.8 m CHI 10.2 m 70.9 m 75.3 m MDK 31.4 m 21.2 m 66.4 m Totals: 205.0 m 349.8 m 518.4 m Percentages: 19% 33% 48% Sandstones in the Mackellar Formation occur as thick sandstone beds, lenticular beds and small-scale discontinuous features enclosed within finer-grained units. Thick sandstone beds are typically greater than two meters thick, and contain less than 10% silty interbeds. Sedimentary structures in the thick sandstones include trough cross bedding up to 30 cm thick, ripple cross lamination, and planar bedding up to 20 cm thick. Soft sediment deformation is common, especially in the form of slumped or contorted beds. Thick sandstone beds increase in abundance toward the top of most Mackellar sections, giving the Mackellar a coarsening upward pattern when viewed at the scale of the entire formation.

Smaller coarsening upward and fining upward cycles, each two to five meters thick, are common within this large-scale coarsening upward pattern.

Thick sandstone bodies are interpreted in this study to have been delta lobes.

Coarser grained delta lobes become more common toward the top of the formation

(Figure 9), indicating that small deltas prograded across the shallow Mackellar basin as the basin infilled with sediment. The rare lobes of coarser elastics found in the middle or lower portions of some Mackellar sections (Figure 10, Figure 11) have two possible interpretations. Localities that were near the margin of the

Mackellar basin may have been influenced by early episodes of gradual lobe migration and deltaic deposition, while more distal locations did not receive coarse­ grained deltaic elastics until the delta systems migrated toward the basin axis.

Regional patterns of sedimentation during deposition of the Mackellar Formation are discussed in later sections. Section CPZ (Figure 10) is interpreted as a 37 Section MMC

A I $ I <£■ 130 - J&- j a r 120 _ Fairchild/Mackellar contact Intsrbeddsd slltstone and sandstone

110 „ Sandstone: Crossbeds, soft sediment slumping, upper stage plane bedding, parallel laminations, rare silty interbeds 100 -

. 90 Coarsens upward

80 _ Shale: Dark gray, silty micaceous, Interbedded shale and slltstone 60% Shale, 40% Slltstone 70 -

60 - Oolerite sill (6 meters thick) Fining upward cycles

50 - Lenticular and wavy bedding 8 40 - Interbedded sandstone and shale (rippled)

30 - 55% Shale, 45% Slltstone and sandstone

Shale: slightly silty 20 - Pagoda/Mackellar contact

10 - Diamictite: fine to medium grain, poorly sorted 0 . ifft&es

v - t■"'•- v , , \ Basal sill (25 meters thick) * ■' - I v .. -'V' > ; >. -.v '•■:

Figure 9: Mackellar measured section MMC (Mt. Weeks) showing the large-scale coarsening upward pattern that is typical of the Mackellar Formation. Smaller scale coarsening upward and fining upward sequences are visible within the section. See Figure 6 for key. 38

Section CPZ

$ 1,/ 200 - ja r js r Fairchild/Mackellar contact 190 _ Poor exposure Interbedded slltstone end sandstone 180 - stwley, micaceous

1 7 0 - Shale: Black, finely laminated Sandstone: Erosional base, moderately well sorted, planar bedding, 160 - pinches out laterally

Sandstone: Gray, micaceous, 150 - poorly sorted, rippled

140 - Interbeddad slltstone and sandstone Slltstone: Gray, poorly sorted, rippled 130 - Coarsens upward Rare sandstone Interbeds 120 - Shale: Black, micaceous, laminated Mackellar/Pagoda contact

110 - SS3WSKS Diamictite: poorly sorted sandstone

Figure 10: Mackellar measured section CPZ (Clarkson Peak) with arrows to illustrate small-scale coarsening-upward sequences. The thick sand body at 147-158 meters is interpreted as an abandoned delta lobe. See Figure 6 for key. 39

Section TGA

250 -

240 . Upper till (50 meters thick)

230 .

Slltstone: Gray-green, baked, 220 - calcareous d lag ana tic concretions

210 -

200 - Sandstone: Gray, poorly sorted, matrix rich

190 . 60% alltatone, 40% shala Intarbaddad aandstone and shala 180 -

30% alltatone, 70% shala 170 - 17 Slltsiona: wavy bedding, flaser bedding, starved ripples 160 - Silty shale: Massive, dark gray, slickensldes Pegoda/Mackellar contact 150 - Olamlctlea: poorly sorted sandstone

Figure 11: Mackellar measured section TGA (Tillite Glacier) showing large-scale coarsening-upward sequence, followed by delta lobe abandonment and return to quiet or deep water conditions. See Figure 6 for key. 40 proximal deltaic deposit, with coarsening upward sequences in lower, middle and upper portions of the measured section. A second interpretation for coarser elastics in the lower portions of the Mackellar Formation is delta bypassing. Disconnected thick sand bodies that do not appear to be part of a coarsening upward sequence

(Figure 11) may have been deposited when coarse sediments bypassed the delta top.

Enhanced offshore transport caused by storms or sudden channel avulsion may occasionally have promoted the deposition of coarse elastics on the lower delta front or prodelta.

Other sandstone bodies are lenticular, have erosional bases, and contain trough cross bedding, asymmetric ripple marks, rare planar tabular cross bedding and current lineation. These beds range from 50 cm to 5 m in thickness, and are laterally continuous for distances of tens to hundreds of meters. Lenticular sandstone beds are interpreted as subaqueous distributary channels that fed the

Mackellar delta lobes (Miller and others, 1987). Sandstones are also found as thin interbeds one to ten cm thick, encased in the predominantly fine-grained portions of the Mackellar Formation. These thin sandstones occur as lenticular pods, and thin, discontinuous wavy beds. Thin sandstone interbeds are interpreted to have been deposited within the mixed lithologic assemblage that is associated with the delta front, and record increased sedimentation rates during pulses of stronger current activity. Large-scale graded bedding and slump structures are rare or absent in these intervals, suggesting that the Mackellar delta front had a very low slope and relatively high stability (Miller and others, 1987). These thin Mackellar sandstones 41 are interpreted to have been deposited from episodic, distal, low density mass flows in a broad, shallow, deltaic setting.

Siltstones in the Mackellar Formation also indicate rapid deposition and abundant sediment supply. Sedimentary structures include starved ripples, wavy and flaser bedding (Figure 12), lingoid ripples, climbing ripples, rare oscillation ripples and rare interference ripples. Siltstones are generally interbedded with shales and/or sandstones, indicating rapid changes in current strength and sediment supply. Lateral continuity of siltstone beds is highly variable, and bed thicknesses range from millimeters to tens of centimeters. A combination of high sediment supply and sudden fluctuations in current velocity resulted in rapid deposition of the silty elastics. These siltstones are interpreted to be part of the proximal delta front complex.

Shales in the Mackellar Formation occur either as thin interbeds in the upper part of the formation, or as thick beds at the base of the formation. The thin shales in the upper Mackellar commonly exhibit fine to medium scale laminae, are silty, and may contain small-scale ripple cross-lamination. These silty shales are interpreted to be delta front deposits within the Mackellar basin, and represent quiet water deposition between sporadic episodes of more rapid sedimentation.

Thick basal shales in the Mackellar Formation are dark gray to black, laminated, and in some cases exhibit silty laminations and rare silty interbeds. Silty laminations are interpreted to record offshore movement by underflows, which reworked and winnowed the sediments and transported oxygen into the deeper basin Figure 12: Wavy and flaser bedding in delta front siltstones and sandstones from the Mackellar Formation, section TGA; Swiss army knife for scale. 43 (Miller and others, 1987). These underflows are important to the interpretation of bottom water conditions in the Mackellar basin, because deltaic underflows may supply oxygen to basinal sediments which are otherwise oxygen-poor (Ettensohn and Elam, 1985). The continued influx of oxygen and sediment laden currents from the Mackellar delta system prevented the development of anaerobic conditions in the deeper basin, even though thick basal shales accumulated during the initial phases of Mackellar deposition. Basal shale intervals measured in this study range from two to 27 m in thickness, and exhibit a consistent regional thickness pattern that may define the original shape of this portion of the Mackellar depositional basin (Figure 13). Thick shales are interpreted as evidence for the longest duration of basinal sedimentation, and are located farther from shore in depressions where quiet water conditions persisted the longest before the onset of deltaic sedimentation.

Isopach patterns of total Mackellar thickness and a summary of paleocurrent directions help to define the shape of the depositional basin in the Beardmore

Glacier region (Figure 14). The shape outlined by contoured thickness is not necessarily the shape of the entire Mackellar basin, but may represent an isolated arm or inlet of an interior waterway in the basin described by Elliot (1975b) and

Collinson (1990). Paleocurrent patterns (Figure 15) from Isbell (1990) are generated from data supplied by Barrett (1968) and Miller and Frisch (1986), and suggest a dominant flow direction from the northwest or north, with a small westerly component at section WLG in the Wahl Glacier area. Figure 13: Contour map showing the thickness of the basal shale in the Mackellar Formation. Thicker shale deposits are interpreted to indicate deeper water and increasing distance from shore. 45

Tvrr 165 E 170 E

170 E

Figure 14: Contour map showing the total thickness of the Mackellar Formation, Beardmore Glacier region, Antarctica. 46

M ackellar Fm. fTTTl Permian £.»vj outcrop

Figure 15: Summary of paleocurrent directions for the Permian Mackellar Formation in the Beardmore Glacier region, Antarctica. Diagram from Isbell (1990); data from Barrett (1968) and Miller and Frisch (1986). Exposures of old cratonic crust that lie to the north, northwest or west of the

Beardmore Glacier region are potential representatives of sources for the detrital sediment that was supplied to the Mackellar Formation and subsequent Permian

units. Much of the detrital sediment in the Mackellar Formation was probably

derived from local erosion of this basement material, although recycled clastic

detritus from the Carboniferous(?)/Permian glaciation may also be present in

Mackellar sediments. This recycled glacial component contains a mixed

provenance signal from a much larger area than the Permian drainage basin. The

Precambrian Beardmore Group has extensive exposures in these areas, although

lesser amounts of Byrd Group and Granite Harbour Intrusives are also present at

the modem land surface. There is no direct evidence that these units were exposed

or contributed sediment during Permian time, but the geologic history of the area suggests the following scenario: Precambrian and Cambrian rocks were part of a deformed margin that was subjected to episodes of tectonic activity (see Chapter I).

During the Ross Orogeny, compression along the paleo-Pacific margin of Antarctica caused deformation and uplift of older marginal-marine sediments and metasediments that belong to the Nimrod Group, Beardmore Group, Byrd Group and Granite Harbour Intrusives (Stump, 1992). Uplift and subsequent erosion of these units is interpreted to have created a series of eroded mountain ranges that formed the craton-ward margin of the Mackellar Sea. Since Precambrian metasediments, metavolcanics and igneous rocks lay to the west, northwest and north of the study area, and since paleocurrent directions were from the west, 48 northwest and north during Permian time, I hypothesize that these older basement sediments and metasediments are representative of the material that served as the source for much of the clastic material, including the sediment found in the

Mackellar Formation.

In this study, the Mackellar Formation has been divided into informal subunits to facilitate a more detailed analysis of stratigraphic patterns in chemistry and mineralogy of the mudrocks. Informal subunits in the Mackellar Formation are based on lithology and sedimentary relations. The lowest black shale in the

Mackellar Formation is referred to as the lower Mackellar (LM), the intermediate interbedded siltstone and mudstone is called the middle Mackellar (MM), and the upper thick sandstone body (when present) is referred to as the upper Mackellar

(UM). The upper thick sandstone body often caps the sequence, but may occur lower in the section and may be repeated. These informal subunits are used for sample identification on tables of chemistry and mineralogy, and are also used on stratigraphic comparisons of chemical and mineral abundances.

The lithologic associations and sedimentary structures described here support the interpretation that the Mackellar Formation was deposited as sediment-laden streams entered a standing body of water. High sedimentation rates allowed marginal deltas to prograde into and finally fill the shallow Mackellar basin. 49 Fairchild Formation

The Fairchild Formation is dominated by sheet-form bodies of medium- to coarse-grained sandstone that were deposited on a broad, flat braidplain (Barrett,

1968; Barrett and others, 1986; Isbell, 1990). Mudstone is rare in the Fairchild

Formation (Table 4), so it was not examined in the same detail as the other formations considered in this study. Very rare calcitic concretions in the Fairchild

Formation have been analyzed for I8Ot 13C and Sr^/Sr86 isotopic compositions in an attempt to provide additional information about source areas and environmental conditions during the deposition of the Fairchild Formation (Lord, 1986; Lord and others, 1988). Sedimentary structures observed in the sandstone beds from the

Fairchild Formation include large scale cross bedding with bed sets up to one meter thick, ripple cross laminae, climbing ripples, upper flow regime parallel lamination, and soft sediment slump structures up to five meters thick. Sandstone sheets and individual sandstone beds have concave upward erosional bases, and erosional boundaries that intersect each other laterally. Quartz pebbles are common at some localities as a lag deposit at the base of the Fairchild Formation. Sandstone sheets and the individual bedsets within these sheets are interpreted as braided stream channel deposits (Barrett, 1968; Isbell, 1990). Multiple stacked channel sequences formed as low gradient braided streams migrated across the broad, flat plain that formed when the Mackellar deltaic complex infilled the post-glacial basin.

Shales and siltstones form less than 3% of the Fairchild Formation

(Table 4), and their sedimentary structures include thin to thick laminae, current Table 4: Lithologic summary of the Fairchild Formation, Beardmore Glacier region, Antarctica.

Lithology Section Shale Siltstone Sandstone

MKR - 0.5 m 17.2 m UMB 1.0 m - 162.0 m TRM 1.0 m 3.9 m 53.7 m

CPZ - 0.6 m 19.4 m Totals: 2.0 m 5.0 m 252.3 m Percentages: <1% 2% 91% 51 ripples and wavy bedding. These fine-grained elastics are interpreted as overbank

deposits, and are rarely preserved in the Fairchild Formation (Isbell, 1990).

Continual reworking destroyed the finer-grained facies and preferentially preserved

the coarser channel sands.

Paleocurrent directions from the Fairchild Formation (taken from Isbell,

1990) are very similar to those described for the Mackellar Formation, with a mean

flow direction from the northwest to the southeast (Figure 16). The detrital source

for Fairchild sediments was located to the northwest of the Beardmore Glacier region (Isbell, 1990), and is hypothesized to have included older cratonic

metasediments and metavolcanics from the Nimrod Group, with minor contributions

from the Beardmore Group, Byrd Group and Ross granites (discussed above).

For this study, the Fairchild Formation was divided into informal subunits

on the basis of height within the measured Fairchild sections. This is not a formal

stratigraphic division, and the only purpose of the subdivision is to facilitate vertical comparison of geochemical information derived from samples collected from the

Fairchild Formation. Samples collected in the bottom half of a measured Fairchild section are referred to as lower Fairchild (LF) samples, and samples collected from the upper half of a measured section of the Fairchild Formation are referred to as upper Fairchild (UF) samples. These abbreviations are used on summary tables of chemical and mineratogical data. For a complete description of the Fairchild

Formation, see Isbell (1990). FAIRCHILD FM.

t7

Figure 16: Summary of paleocurrent directions for the Permian Fairchild Formation in the Beardmore Glacier region, Antarctica. From Isbell (1990). 53 Bucklev Formation

The Buckley Formation is composed of sandstone, siltstone, shale and coal that was deposited in braided stream systems, located on what may have been the landward margin of an interior basin (Isbell, 1990; Collinson, 1990). Continued subsidence of the basin preserved a complex group of sediments, including finer- grained lithologies that represent a variety of depositional environments (Table 5).

Very rare calcitic concretions and rare carbonate horizons in the Buckley Formation have been analyzed for lsO, 13C and Sr^/Sr86 isotopic compositions in an attempt to provide additional information about source areas and environmental conditions during the deposition of the Buckley Formation (Lord, 1986; Lord and others,

1988). Sedimentary structures and lithologic associations described in this study are also used to identify several depositional environments within the Buckley

Formation.

The lower portion of the Buckley Formation is dominated by thick sandstone bodies (Barrett, 1968; Barrett and others, 1986; Isbell, 1990). These bodies are less dominant in the upper portion of the Buckley Formation, although they remain an important component. Sandstone beds within these bodies range from 50 cm to 15 m in thickness, and occur both as sheets and as channel-form bodies. Channel-form bodies have erosional, concave upward bases, and extend laterally for tens to hundreds of meters. Sheet sands have undulating lower surfaces and commonly extend for thousands of meters. Sedimentary structures in the thick sandstone bodies include trough cross beds up to one meter high, tabular 54 Table 5: Lithologic summary of the Buckley Formation, Beardmore Glacier region, Antarctica.

Lithology Section Shale Silts tone Sandstone Coal MMD 42.2 m 10.2 m 181.8 m 10.0 m MPI 77.6 m 119.1 m 148.2 m 21.9 m MTR 8.3 m 119.1 m 160.4 m 18.3 m MAR 113.4 m 97.9 m 136.4 m 19.6 m LPP 4.5 m 24.8 m 36.2 m 2.5 m MBO 3.0 m 25.9 m 102.2 m 7.9 m Totals; 249.2 m 367.2 m 759.8 m 80.2 m Percentages: 17% 25% 52% 6% 55 planar cross bed sets ten to 30 cm thick, and asymmetrical ripple marks. Large- and small-scale fining-upward sequences are common. Small-scale fining-upward sequences are centimeters to decimeters thick, and occur as either a subtle upward decrease in grain size or a systematic upward decrease in the size of the sedimentary structures. Small-scale fining-upward sequences are interpreted to be evidence for decreasing flow velocity due to decreasing discharge or migration of the channel axis. Large-scale fining-upward sequences are up to tens of meters thick, with thick sandstone at the base and a progression to finer-grained lithologies upward. These sandstone bodies are interpreted as braided stream channels and multi-layered channel complexes, and include associated splays (Isbell,

1990).

Siltstone, shale and coal exhibit lithologic associations that are important for interpreting depositional environments within the Buckley Formation. The large- scale fining-upward sequences discussed above generally grade into siltstone, shale and coal. These finer-grained units contain ripple marks, mudcracks, plant fossils and paleosol horizons (Figure 17), which indicate the presence and preservation of floodplains near the coarser-grained channel systems. Other fine-grained units do not fine upward, but instead contain laminated and interbedded layers of siltstone and shale. Laminated units are interpreted as ponded deposits, and represent low- lying areas near the Buckley river systems (Isbell, 1990),

Coal beds in the Buckley Formation are both allochthonous and autochthonous (Isbell, 1990). Allochthonous coal beds range from five centimeters Figure 17: Rooted horizon within the Buckley Formation illustrates paleosol development. Arrows point to thin root traces within the siltstone bed. From Lamping Peak section LPP; Swiss army knife for scale. 57 to more than one meter in thickness, and are encased in shale, siltstone or sandstone beds. Allochthonous coals pinch out laterally within two to 200 m.

These thin coal beds commonly contain silty or shaley interbeds, and formed in low-lying areas where organic matter accumulated with episodic clastic influx

(Isbell, 1990).

In contrast to the allochthonous coal beds, autochthonous coal beds range from ten centimeters to more than four meters in thickness, and are commonly underlain by rooted horizons. Autochthonous coal beds cap fining-upward sequences (Figure 18), and are laterally traceable for hundreds to thousands of meters along the well-exposed outcrops in the Beardmore Glacier area.

Autochthonous coals formed in broad lowlands or along the margins of lakes that were distal to the river channel, and therefore were infrequently influenced by floods and clastic influx (Isbell, 1990).

The Buckley Formation is divided into two informal subunits on the basis of paleocurrent data and sedimentary petrography performed by Isbell (1990). Barrett

(1968) recognized a similar lithologic distinction within the Buckley Formation,

The lower Buckley Formation is designated "LB" on data tables of chemical and mineralogic results, and refers to sediments deposited by paleocurrents with a general northwest to southeast flow (Figure 19). This is similar to paleocurrent directions discussed above for the Mackellar and Fairchild Formations.

The upper Buckley Formation informal subunit is designated "UB" on tables of chemical and mineralogic results, and marks the occurrence of two events. 58

Figure 18: Coal bed as cap to fining upward sequence in the Buckley Formation, section MAR. 1.5 meter bamboo pole for scale. 59

Eastern Region

12 western Region

LOWER Eastern Region BUCKLEY FM. Western Region

Figure 19: Summary of paleocurrent directions for the Permian lower Buckley Formation informal subunit in the Beardmore Glacier region, Antarctica. From Isbell (1990). 60 Paleocurrents reversed direction at the boundary between the lower and upper

Buckley Formations (Figure 20), and flowed from southeast to northwest for the remainder of Buckley deposition. Abundant volcaniclastic detrital grains also appeared for the first time at the base of the upper Buckley Formation. This volcaniclastic influx was identified petrographically by Barrett (1968) and Isbell

(1990), and consultation with John Isbell helped to determine the boundary between the lower and upper Buckley Formation informal subunits in most of the stratigraphic sections used in this project. These informal stratigraphic units are used to compare chemical and mineralogical differences that resulted from the paleocurrent reversal and volcaniclastic influx.

In summary, the Buckley Formation was deposited in a variety of environments within the overall context of a braided stream setting. Braided stream channel deposits predominate in the lower Buckley, but deposits of finer grained floodplain and peat-forming environments are more abundant in the upper Buckley.

Sedimentary structures and facies associations allow the distinction of these different environments.

Summary

Field relationships, sedimentary structures, and lithologic descriptions have been used to interpret the depositional environments of four Carboniferous/Permian formations in the Beardmore Glacier region. The results from this study and previous work identify the Pagoda Formation as a glacial deposit, the Mackellar 61

1T0*E

j £ y } .

U pper | f w / Buckley Fm.

Parmlon outcrop

Figure 20: Summary of paleocurrent directions for the Permian upper Buckley Formation informal subunit in the Beardmore Glacier region, Antarctica. From Isbell (1990). 62 Formation as a shallow deltaic deposit, and the Fairchild and Buckley Formations as braided stream deposits. CHAPTER III

ORGANIC CARBON DISTRIBUTION

Much of the information in this chapter was published previously in the

1991 American Geophysical Union Contributions to Antarctic Research n,

Antarctic Research Series, volume 53, p. 33-65. The portion of the paper that discusses the organic carbon component of Permian sediments from the Beardmore

Glacier area is presented here in its entirety, with additions to the discussions on methods, carbon/sulphur ratios, results of organic carbon analysis and reproducibility of organic geochemical data.

Introduction and purpose

The overall objective of this project is determine the provenance, paleoclimate and diagenesis of Permian sediments from the Transantarctic

Mountains. Within this framework, the composition and distribution of organic matter in fine-grained sediments from the Beardmore Glacier area provides information about sediment source areas, post-glacial climatic changes and post- depositional alteration. The first step in organic carbon analysis is to identify the factors that control the distribution of organic material in Beacon sediments. This

63 64 is accomplished by reviewing the variables that can, in general, control the occurrence of organic matter in sedimentary rocks, and by evaluating the importance of each variable in this study. Careful evaluation of these factors reveals that, in this study area, the amount of organic carbon preserved in sedimentary rocks is largely controlled by the original productivity and by later thermal alteration.

With these controlling factors in mind, several analytical methods are used to provide more information about organic carbon compounds in a post-glacial sedimentary sequence. Diagenesis and thermal alteration are examined by analyzing total organic carbon (T.O.C.) contents and the reflectance of vitrinite phytoclasts (organic particles), and comparing these results to field measurements of proximity to nearby intrusive bodies. Provenance, or more specifically, the source of the organic carbon, is analyzed by kerogen typing and measuring C/S ratios.

Kerogen typing distinguishes terrestrial carbon clasts from marine carbon clasts, while C/S ratios provide chemical evidence about the marine or non-marine nature of the sediments. Paleoclimate and climatic changes are examined by comparing average T.O.C. measurements from each formation, with the interpreted conclusion that the organic carbon content is related to the productivity of the original depositional environment. This combination of analytical strategies provides a multi-faceted approach to evaluation of the provenance, paleoclimatic conditions and diagenesis of Permian elastics from the Transantarctic Mountains. 65 Methods

Field work was conducted during the 1985/86 and 1990/91 austral summers, in conjunction with field parties from The Ohio State University, Vanderbilt

University and Augustana College. During this time stratigraphic sections were measured, lithologies and lithologic relationships were described and fine-grained samples were collected for later laboratory analyses (see chapters II, IV and V for additional description of field methods and results of field and laboratory studies).

Samples chosen for the various types of organic carbon analysis were quarried from fresh outcrop surfaces and carefully packed to minimize contamination by foreign carbon compounds. All samples were shipped to The Ohio State University, where they were split and prepared as necessary for each method of carbon analysis.

Upon completion of the field work, 83 samples were selected for vitrinite reflectance analysis. Vitrinite is a residual, insoluble carbon compound that becomes reflective when heated. The reflectivity of vitrinite is directly related to the amount of heating (Figure 21), so vitrinite reflectance provides an accurate method for determining the extent of alteration in sedimentary rocks (Bostick,

1979). Vitrinite reflectance measurements were performed by a commercial laboratory (DGSI, The Woodland, Texas) using procedures outlined by Dow (1977) and Dow and O’Connor (1980). In this technique, approximately 20 grams of sample were digested in hot 20% HC1 and 70% HF, washed until the pH was neutral, and centrifuged to concentrate the organic component Multiple acid baths remove the silicate component and concentrate the organic compounds. Figure 21: Correlation of vitrinite reflectance (Ro%) with other maturation indices.maturationother vitrinite with(Ro%) reflectance Correlation of 21:Figure

ho*‘*Q1 M0A-03N Jlllino* - HDIM z > o Vitrinite reflectance increases as thermal alteration increases. From Dow From thermalalterationincreases.increasesreflectanceasVitrinite (1977). D R Y G A S PRESERVATION LIMIT PRESERVATION S A G Y R D W ET G A S FLOOR S A G ET W LFLOOR AMORPHOUS (OIL) MIXED EEAIN N DESTRUCTION AND GENERATION

IIPTINITIC __ _ y _ OE O PETROLEUM OF ZONES L

t e w / L J VGAS/ S A G -V EK I GENERATION OIL PEAK - - - - GEN S A - g \ DRYf PEAK PEAK W E T.G A S GEN S A T.G E W PEAK COALY (GAS) TYPE HUMIC \ / DRY

99 99 85 80 65 75 70 e n x n m o o ■ 1*1X z z > sa H X S z n S — ...... - 109 60 99 80 70 50 e -4 X z o n X > n e m M 2 » - h ... | IUKI HI*) (nil 0 mi

i- i i- :+> (-1 1-1 1 + 1 KNG|

2 1 4 $ I HRA ATRTO IDX TAI) A (T INDEX ALTERATION THERMAL 66 67 Moisture was removed by freeze-drying the organic concentrate, and the resulting powder was cemented in an epoxy matrix.

Polished kerogen concentrates were examined using a Zeiss Universal reflecting microscope at a magnifying power of 500X and a coherent light source with oil immersion mounts. In this step, light was reflected from the polished stub, and the reflected beam was passed through a photomultiplier to a digital display and a Tektronix 4051 computer. An operator noted individual readings that were performed on oxidized, recycled or altered kerogen particles so that these values could be excluded from the data base. Measurements were taken for four or more different carbon particles within each sample, and the results were averaged to provide a mean reflectance in oil (Ro) for each sample.

An additional thirty-seven samples were selected for visual kerogen type analysis. Kerogen typing was also performed by DGSI (The Woodlands, Texas) for

Dr. Molly Miller of Vanderbilt University, and results are reported here courtesy of

Dr. Miller. Kerogen is altered organic matter, and has morphologies and internal structures that are characteristic of specific parent materials (Tissot and Welte,

1984). The major kerogen groups that can be visually identified by this method are amorphous or alganitic kerogen, exinite, vitrinite and inertinite. Alganitic kerogen is usually derived from plankton, and indicates that a marine or large freshwater basin contributed organic material to the sediment The terms alganitic and amorphous kerogen are commonly used synonymously, and can also refer to kerogen derived by oxidation or microbial reworking of complex organic debris 68 (Tissot and Welte, 1984). Exinite is composed of spores, cutin, resins and waxes, and the presence of exinite demonstrates that a terrestrial source contributed organic matter to the sediment (Eglinton and Murphy, 1969). The vitrinite and inertinite groups are derived from higher land plants, and also indicate a terrestrial source for organic compounds (Dow, 1977). These broad groupings based on visual identification of kerogen compounds are an important provenance tool in the study of organic-rich sediments.

Kerogen typing was accomplished by extracting and concentrating the insoluble organic compounds that occur in sedimentary rocks. Samples were prepared using the extraction and polishing techniques described above for vitrinite isolation. Polished kerogen stubs were viewed under reflected light with a Zeiss universal microscope at a magnification of 500x. Both normal and fluorescent

(xenon) light sources were employed, since some kerogen types are distinguished by their color under fluorescent light. A trained operator made visual estimates of the abundances of the common kerogen types in each sample, and tabulated the results. In this study, average kerogen abundances are compared between units to show potential changes in the marine or non-marine source of sedimentary carbon particles.

Total organic carbon content (T.O.C.) was measured at The Ohio State

University using a Coulometrics carbon analyzer. In this method, samples were ground in a ball mill and sieved to 200 mesh to ensure homogeneity. The powdered samples were split, and 20 to 50 mg portions were analyzed for total 69 carbon and inorganic carbon content. A Coulometric carbon analyzer was used to

obtain total organic carbon content by difference using the following formula:

T.O.C. = (Total carbon) - (Inorganic carbon)

Total carbon was measured by placing the weighed sample in a combustion

chamber that is heated to 900° C. A carrier gas of pure oxygen was passed over

the sample, and as combustion occurred, the carrier gas removed any C02 that

evolved as a by-product of the oxidation of organic material and carbonate

minerals. The coulometer then performed an automatic chemical titration to

measure the amount of evolved COz, and converted C02 abundance to weight

percent total carbon in the sample. Statistical checks of changing C02

concentrations determined the proper length of time for each sample run, and when

C02 concentrations in the carrier gas were negligible, the final weight percent of

total carbon was calculated and automatically entered into an Epson microprocessor control unit. At least two replicates were run for each sample, and every tenth sample was run four times to determine the precision of the procedure.

Inorganic (carbonate) carbon concentrations were measured by placing the weighed sample in an enclosed chamber that contained a measured aliquot of 2N perchloric acid. In this chamber, carbonate carbon reacted with perchloric acid to produce C02, and was then removed from the chamber by a stream of scrubbed room air that acts as a carrier gas. An automatic chemical titration measured the amount of evolved C02 in each sample, and results were converted to weight 70 percent inorganic carbon. Two replicates were run for each sample, with every tenth sample run at least four times to check the statistical precision of the process.

The final analytical method employed in this part of the study was measurement of carbon/sulfur ratios. C/S ratios were measured by XRAL (Don

Mills, Ontario, Canada) and by Dr. Robert Berner (Yale University). Both laboratories used a LECO carbon/sulfur analyzer to measure carbon and sulfur contents. Carbon analysis performed by these laboratories is very similar to the method described above using the Coulometric brand carbon analyzer, with organic carbon contents determined by difference using the rapid ashing technique of Krom and Berner (1983). Organic carbon measurements obtained by this method were compared to replicate analyses from the Coulometrics carbon analyzer at The Ohio

State University.

Reduced sulfur contents were used in conjunction with organic carbon contents to distinguish marine from non-marine environments (Bemer and Raiswell,

1983; Bemer and Raiswell, 1984). This method relies on the observation that marine sediments have high pyrite sulfur contents as a result of an abundant sulfate ion supply in sea water, while fresh water sediments are relatively poor in pyrite sulfur as a result of a limiting sulfate ion supply in fresh water environments of deposition (Bemer and Raiswell, 1983). Sulphur was measured using a LECO sulfur analyzer that combusted the sample and converted all sulfur to S02. The amount of sulfur in the evolved S02 was measured by titration, and results were reported in weight percent. Comparison of measured C/S ratios to the standard 71 graph produced by Bemer and Raiswell (1983, 1984) provides a reliable method for determining the marine or freshwater origin of sedimentary rocks.

Results

Vitrinite reflectance analyses

Complete results of vitrinite reflectance analyses are shown in Appendix A.

Of the 83 samples analyzed, 61 samples yielded geologically significant results.

Data were judged to be significant if they met the following criteria: the degree of alteration must fall within the standard vitrinite scale (Dow, 1977), and a statistically significant number of phytoclasts must be present in each sample. Data were not used for further interpretations if the vitrinite clasts were described as

"coked". Coked samples contain highly altered carbon compounds that have been heated beyond the vitrinite phase. In other study areas, coked samples are found in close proximity to intrusive bodies (John Castaho, personal communication). Data were also discarded if the sample was described as "barren" or if less than four phytoclasts were measured. Barren samples do not contain appreciable amounts of vitrinite (usually due to a low total organic carbon content), and samples with less than four measured phytoclasts do not yield statistically significant results. These minimum standards ensure that interpretations and conclusions based on vitrinite reflectance analyses are geologically significant.

Mean vitrinite reflectance values are summarized by formation in Table 6.

The mean vitrinite reflectance value for all samples analyzed in this study is 72 Table 6: Stratigraphic summary of vitrinite reflectance data. Vitrinite reflectance does not vary significantly between the four studied formations.

Formation MeanRo Standard Number of Deviation samples (n)

Pagoda 3.13 not applicable 2

Mackellar 2.44 1.00 24

Fairchild 2.37 0.64 3

Buckley 2.37 1.15 32

All units 2.47 1.11 61 73 2.47 Ro. On a broad scale, this could be used as an average background heating level for sediments from the Beardmore Glacier area. Upon closer analysis, it is evident that smaller variations are responsible for a wide variation in background heating levels. High standard deviations associated with mean Ro values (Table 7) indicate that there are significant small-scale variations in the extent of thermal alteration. These differences were examined stratigraphically and geographically.

Differences between the mean Ro for the four formations studied are not statistically significant, so no conclusions can be drawn about stratigraphic variations in the background heating level.

Mean vitrinite reflectance values were also tabulated by geographic area, and inspection of these data reveals that there are significant geographic variations in the background heating level. Samples from sections in the far northern part of the study area (sections MKR, MMD and TRM) have consistently low mean Ro values (Table 7). Mean Ro increases to the south/southeast, and reaches a maximum in the north/central and south/central parts of the study area (Table 7).

Section MBO, located in the far southern part of the study area, indicates a decrease in background heating levels in the direction of the Polar Plateau.

Kerogen type analyses

Complete results of kerogen analysis are shown in Table 8. The objective of these analyses is to make a visual identification of the kerogen types present in each sample, and identify geographic and stratigraphic trends in kerogen 74 Table 7: Geographic summary of vitrinite reflectance data. Mean vitrinite reflectance is lowest in the far northern edge of the study area, increases toward the central region, and decreases again in the far south.

Geographic Mean Ro Standard Number of Area Deviation samples (n) Far North (Sections MKR, MMD, TRM) 1.28 0.62 17

North/Central (Sections MMQ, MMA, MMC, 2.76 0.41 13 MTM, CPZ, WLG) South/Central (Sections MPI, MTR, TGA, 3.29 0.95 24 MAR, TGF, MDK, LPP) Far South (Section MBO) 2.05 0.66 8 75 Table 8: Results of kerogen type analysis. Sample names follow the convention described in Figure 6. Vitrinite and inertinite are the most common kerogen groups, and indicate a terrestrial source for the carbon compounds found in Beacon sediments.

ORGANIC MATTER TYPE (%) KEROGEN TYPE BITUMEN S am p le F o rm atio n Amorphous Exinite Vitrinite Inertinile TGA41.0 LP —— — — — TGA96.7 UP 5 0 40 55 0 MMA18.0 LM 0 0 Trace? 0 0 TGA 151.7 LM —— — — — TGA 158.0 LM ? 0 Trace Trace 0 TGA 160.0 LM — ——— ------M B0 38.5 LM 5 0 35 60 0 CHI 132.6 LM ?60 0 ?20 ?20 0 M DK20.0 LM ?50 0 ?25 ?25 0 MDK20.5 LM 20 5 50 ?25 0 TGA 166.0 MM ? 0 Trace Trace 0 TGA 173.0 MM Trace — ——— MKR42J2 MM 10 0 50 35 ?5 MMD 11.0 MM 55 0 15 30 0 MMD27.0 MM 5 0 40 55 0 MTM 258.0 MM Trace 0 Trace 0 0 M BO65.0 MM 30 0 ?35 ?35 ? MBG67.8 MM 5 0 25 70 0 TGA 220.0 UM Trace 0 Trace Trace 0 MMD 115.5 UM 35 0 50 15 0 M BO88.0 UM 5 0 45 55 0 MBO 100.0 UM 25 0 ?30 ?45 ? MBO 104.0 UM 0 0 40 60 0 MBO 125.0 UM 15 0 10 75 0 MDK 119.0 UM Trace 0 Trace Trace 0 MMD 270.0 LB 15 20 40 25 0 MMD 283.5 LB ?10 10 45 30 5 MMD 295.5 LB 0 40 45 15 0 MMD 318.5 LB 5 30 45 20 0 MMD 384.0 LB 0 20 50 30 0 MMD 417.0 LB 5 5 30 60 0 MMD 440.5 LB 5 0 35 60 0 MA6 14.4 LB Trace 0 Trace Trace 0 BOB 89.8 LB 10 0 50 40 0 MA4 37.0 UB 10 ?10 40 40 0 MA5 114.1 UB 20 ?5 40 35 0 76 distribution. No geographic trends were identified within the limited data set,

although two stratigraphic changes in kerogen content indicate changes in the

supply of organic matter between the Mackellar and Buckley Formations.

Most samples are dominated by vitrinite or inertinite, indicating that carbon

compounds in Permian sediments from the Beardmore Glacier region were derived

from higher land plants. An exception to this generalization is an increase in

amorphous/alganitic kerogen in the Mackellar Formation (Figure 22). Amorphous

or alganitic kerogen is often produced by simple aquatic algae, and the increase

associated with the Mackellar Formation is interpreted to represent primary algal

productivity in the water column of the Mackellar sea. A more detailed breakdown

of these data reveals that the basal black shales, informally termed the "lower"

Mackellar Formation, have the highest amorphous/alganitic kerogen content

(Figure 23). Algal activity appears to have been greatest during deposition of the

basal shales, then decreased upward into the sandier beds of the "middle" and

"upper" Mackellar Formation (Figure 23). This apparent decrease in algal

abundance may be a result of inhospitable conditions in the turbid deltaic environment, or it may be a dilution effect caused by an increase in sediment

supply.

The second significant stratigraphic change in kerogen content is the

addition of exinite that coincides with the onset of Buckley deposition (Figure 22).

The probable source of the exinite is a Glossopteris flora that first appears in the

Beacon sequence in association with coals of the Buckley Formation. Stems, leaves Figure 22: Visual kerogen identification in the Permian portion of the Beacon the of portion Permian the in identification kerogen Visual 22: Figure Kerogen Type (%) r I Amorphous IAmorphous r ** No Samples analyzed analyzed Samples No ** y irnt n ietnt eie rmtretilsucs Te terms The sources. terrestrial from derived dominated inertinite are and vitrinite Formations by Buckley and Mackellar Pagoda, The Supergroup. "amorphous" and "alganitic" kerogen are often used synonymously. used often are kerogen "alganitic" and "amorphous" r ... : _ _ ~ Permian Portion, Beacon Supergroup Beacon Portion, Permian Average Kerogen Type by Formation by Type Kerogen Average Pagoda M ackellar Fairchild** Buckley Buckley Fairchild** ackellar M Pagoda X EileVtileInertinite Vitrinlte Exinlte I ^Oflliation Alganidc Alganidc Amorphous/ in Note increase increase Note Kerogen I 1 ------} 77 Figure 23: Visual kerogen identification in the informal subunits of the Mackellar Mackellar the of subunits informal the in identification kerogen Visual 23: Figure Kerogen Type (%) |Aopos| Exinite | | Amorphous | I Formation. Amorphous (alganitic) kerogen is most abundant in the black black Formation. the in Mackellar "lower" abundant the most of is shales kerogen (alganitic) Amorphous Formation. * " M ackellar Formation Kerogen Content Kerogen Formation ackellar M lwr "ide "upper" "middle" "lower" Mackellar Formation Subunits Formation Mackellar Average Kerogen Type by Subunit by Type Kerogen Average Vltrinite Inertinite 78 79 and roots from the glossopterids provided potential sources for the cuticles, resins

and waxes that were altered to form exinite. Vascular tissues from these plants also

contributed to the detrital vitrinite component observed in the Buckley Formation.

Total organic carbon analyses

Complete results of total organic carbon (T.O.C.) analyses are shown in

Appendix A. Mean T.O.C. values are summarized for each formation and for

informal subunits of each formation. The appendix includes values measured in

unaltered and thermally altered samples, and the standard deviation is reported after

running every tenth sample four times. Results indicate excellent reproducibility of

total carbon and inorganic carbon contents, with maximum (worst case) standard

deviations from replicate sample runs equal to 0.02% for the Pagoda Formation,

0.04% for the Mackellar Formation, 0.03% for the Fairchild Formation, and 0.88%

for the Buckley Formation. Higher standard deviations in the Buckley Formation accompany higher mean carbon contents, and still support the internal consistency of T.O.C. measurements.

Carbon/sulfur analyses

Results of carbon/sulfur (C/S) analysis are shown in Table 9. Sulfur concentrations are uniformly low and reproducible, but there is a problem with organic carbon measurements performed by XRAL laboratories. A comparison of

T.O.C. contents from replicate samples submitted to both commercial laboratories 80 Table 9: Complete results of carbon/sulfur analysis. Samples names use the abbreviations described in Figure 6. Samples are grouped by formation and informal subunit, and means and standard deviations are determined for each group.

Organic Carbon/Sulfur Ratios Sample % T.O.C. % T.O.C. % Sulfur Carbon/Sulfur *=XRAL analysis (Ohio State Ratio +«Yale analysis analysis) TGA41.0 LP +0.12 0.2 <0.01 20 TGA 1.0, rep. #1 LP *0.05 0.1 0.02 5 TGA 1.0, rep. #2 LP *0.05 0.1 0.02 5 TGA 1.0, rep. #3 LP *0.05 0.1 0.02 5 TGA 96.7 UP +0.10 0.3 <0.01 30 MTM 186.2 UP *0.05 0.4 0.02 20 CHI 91.0 UP *0.08 0.1 0.01 10 MKR6.0 LM *0.05 0.4 0.02 20 CPZ 123.4 LM *0.02 0.2 0.02 10 TGA 151.7 LM +0.13 0.3 <0.01 30 TGA 160.0 LM +0.15 0.2 <0.01 20 MBO 38.5 rep. #1 LM +0.86 0.9 <0.01 90 MBO 38.5 rep. #2 LM *0.10 0.9 0.02 45 CHI 132.6 LM *0.04 0.3 0.02 15 TGA 173.0 MM +0.04 0.2 <0.01 20 MMD 11.0 rep. #1 MM +0.30 0.4 <0.01 40 MMD 11.0 rep. #2 MM *0.05 0.4 0.02 20 MMD 27.0 MM +0.56 0.6 <0.01 60 MBO 67.8 MM +1.25 1.3 <0.01 130 MMD 115.5 UM +0.19 0.4 <0.01 40 MBO 88.0 UM +2.02 2.3 <0.01 230 MBO 104.0 UM +0.98 1.0 <0.01 100 MBO 125.0 rep. #1 UM +1.28 1.1 <0.01 110 MBO 125.0 rep. #2 UM *0.10 1.1 0.04 27.5 MBO 170.0 UF *0.14 2.8 0.03 93 MMD 270.0 LB +4.80 4.9 0.05 98 MMD 295.5 LB +26.3 26.6 0.15 177 MMD 318.5 LB +27.2 40.5 0.17 238 MMD 384.0 LB +58.7 58.0 0.25 232 MMD 440.5 LB +12.0 13.3 0.04 332 BOB 116.1 LB *0.13 5.9 0.04 148 81 reveals that T.O.C. analyses from XRAL are consistently low, while T.O.C. contents obtained from the Yale lab are in close agreement with numbers obtained at Ohio State. An average coefficient of variability [(standard deviation / mean) x

100] was calculated for each set of analyses to measure the difference between the three sample sets. The coefficient of variability is 15.9% for comparison of the

Ohio State/ Yale values, and 50.1% for comparison of the Ohio State/ XRAL values. Higher agreement (less variance) between the Ohio State and Yale T.O.C. numbers casts doubt on the validity of the XRAL T.O.C. numbers. For this reason,

C/S ratios in Table 9 were calculated using T.O.C. values from Ohio State and sulfur values from XRAL and the Yale lab.

C/S ratios determined by this method fall into the fresh water field defined on the graphs of Berner and Raiswell (1983; 1984). These results agree with interpretations based on 180 isotopic data obtained from carbonate concretions (Lord and others, 1988), and studies based on sedimentologic information (Miller and others, 1987; Miller and others, 1990). Low sulfur content is the controlling factor in the C/S relationship, and low sulfur contents are characteristic of terrestrial sedimentary rocks. This indicates that the source for organic compounds and sulfur was non-marine, and that these sediments were deposited in a non-marine environment. 82 Discussion

Factors that control the occurrence of organic carbon in sedimentary rocks

must be examined before organic carbon contents can be interpreted properly. The

first part of this section is a general discussion of the factors that can control the input and preservation of organic carbon in the four formations studied. When the controls on carbon distribution have been identified, organic carbon contents from

Carboniferous/ Permian sediments in the Victoria Group are used for two different purposes. First, a combination of vitrinite reflectance, field relations and T.O.C.

data are used to demonstrate the utility of carbon compounds as indicators of alteration in thermally modified strata. Second, when the extent of thermal alteration has been identified, the characteristics of relatively unaltered samples are combined with field observations to develop general interpretations about depositional environments and organic productivity in the Beardmore Glacier region during the Late Paleozoic.

Controls on organic carbon distribution in Beacon sediments

Many factors control the occurrence of organic matter in sedimentary rocks.

These factors include grain size, type of organic matter, level of primary productivity, amount of bioturbation, dissolved oxygen content, extent of bacterial degradation, carbon contribution from recycling, sedimentation rates, and extent of post-depositional alteration (Demaison and Moore, 1980; Jones, 1983). Organic carbon content in the resulting sedimentary rock is a balance between factors that 83 control the input of organic matter, and factors that control the destruction of organic matter. The importance of these factors in Beacon sediments must be evaluated before the results of organic carbon analyses can be interpreted.

Grain size is a potential control on organic carbon distribution, since organic carbon content generally increases as sediment grain size decreases (Jones, 1983).

In this study, grain size effects have been minimized by sampling only the finest- grained intervals from each formation. Samples used for organic carbon analyses are either shales or siltstones. This method of limiting the effects of grain size is imperfect, but mudrocks from the Beacon Supergroup are highly indurated, and conventional methods of disaggregation and mechanical size separation are ineffective. Within these limits, every effort was made to ensure that samples from each of the four formations are consistently fine-grained.

The preservation of organic matter in sedimentary rocks is related to the type of organic matter present. Some organic compounds are very resistant to alteration, while other organic compounds are easily degraded or altered (Eglinton and Murphy, 1969; Tissot and Welle, 1984). Kerogen type data (Figure 23) used earlier to describe the sources of organic matter are also applicable to this problem.

Averaged analyses show that kerogens (insoluble organic matter) in the Beardmore

Glacier region do not vary significantly, since vitrinite and inertinite are the dominant kerogen types in each formation. The major source of carbon to these sediments is consistently terrestrial, therefore eliminating the possibility that 84 changes in the type of organic carbon are responsible for differences in the preserved organic carbon contents.

Recycling of organic material from older sedimentary rocks is another factor that many authors have cited as an influence on T.O.C. distribution in sedimentary rocks. An example of recycled organic carbon is discussed by Friis and others

(1979), who found Carboniferous spores in Tertiary sediments from the North Sea.

This is an unusual pathway in the global carbon cycle (Welte, 1969), but recycling may be important in glacial environments. Glacial processes emphasize mechanical weathering, in contrast to the chemical weathering that is dominant in many other environments. Since mechanical weathering is less likely to destroy carbon compounds, a higher proportion of recycled carbon may be supplied to glacially derived sediments.

Dissolved oxygen contents, the amount of bioturbation and the degree of bacterial degradation in sediments are additional factors that influence the post- depositional preservation of organic carbon. Preservation of organic matter is favored when biological activity is low or absent, especially under anoxic bottom conditions where a lack of bioturbation prevents disturbance and oxidation of the existing carbon compounds. Degradation of organic carbon is favored when biologic activity is high, the sediment/water interface is oxic, or when microbial activity destroys the carbon compounds after deposition.

In the case of the Pagoda, Mackellar, Fairchild and Buckley Formations, it is difficult to quantitatively evaluate the degree of bioturbation, oxygenation, or bacterial degradation. The important consideration for this study, however, is whether evidence exists for significant differences in these conditions between the four formations. Differences in bioturbation, oxygenation or bacterial degradation could indicate that the proportion of the original organic carbon that has been preserved varies significantly through the Victoria Group. Bioturbation is rare throughout the Permian sediments, but the very limited trace fossil assemblage that is present includes vertical burrows that are similar in the Mackellar and Buckley

Formations (Miller and others, 1987). The presence of similar trace fossils and uniform (albeit rare) amounts of bioturbation in the Mackellar and Buckley

Formations indicates that the effects of bioturbation on the preservation of organic carbon do not vary significantly for these two formations. Although discrete trace fossils were not observed in the Pagoda and Fairchild Formations, the overall scarcity of bioturbation throughout the Permian section suggests that the preservation of organic carbon is not controlled by variations in bioturbation intensity.

In addition to the evidence provided by trace fossils, the interpretations of depositional environments presented in Chapter II provide indirect evidence about the degree of oxygenation during the deposition of the Victoria Group. Glacial

Pagoda sediments were probably deposited under oxic conditions due to the turbulent and oxygenated nature of glacial movement and outwash. A lack of varves in Pagoda sediments may also indicate deposition under oxygenated conditions, since varves are often associated with anoxia in modem pro-glacial 86 lakes. In the Mackellar Formation, rapid sediment deposition by deltaic underflows enhanced water column mixing in the basin, thereby oxygenating the water column and the underlying sediments. Fluvial channel environments of the Fairchild and

Buckley Formations were also oxygenated, but flood plain environments of the

Buckley Formation may have experienced low oxygen conditions. Ponded or peat- forming environments in the Buckley Formation are examples of environments that were probably anoxic or oxygen deficient. This results in higher preserved T.O.C. contents in the ponded or swampy environments. With this exception, the influences of bioturbation and oxygen content on early post-depositional degradation of organic matter appear to have been relatively uniform through deposition of the Pagoda, Mackellar, Fairchild and Buckley Formations.

The relationship between changes in sedimentation rate and preservation of

T.O.C. cannot be easily estimated from the available data. Sedimentation rates were high during deposition of sandstones from the Mackellar, Fairchild and

Buckley Formations, as evidenced by sedimentary structures such as flaser bedding and wavy bedding, and the presence of thick channel deposits. Sedimentation rates in the finer-grained facies studied in this project are more difficult to estimate.

There may have been differences in sedimentation rates between shales and siltstones in the four Permian formations, and this ultimately affects the preservation of organic carbon compounds. Differences in T.O.C. content must be evaluated in light of all possible data, including sedimentary structures, grain size, 87 and inferences of sedimentation rates before large-scale patterns can be properly interpreted.

The previous discussion suggests that the effects of grain size, kerogen type, amount of bioturbation, and oxygenation of the sediments on organic carbon preservation should be relatively uniform throughout the formations examined in this study. Factors that are responsible for minor variations in organic carbon preservation include differences in sedimentation rate and grain size, but these probably are not major controls on the T.O.C. content of Beacon sediments. Two variables that have not been discussed as controls on the organic carbon content are reduction in T.O.C. due to thermal alteration, and variable input of T.O.C. due to changes in productivity at the time of deposition. These variables are now examined as controls on the organic carbon content of fine-grained sedimentary rocks from the Beardmore Glacier area.

Vitrinite reflectance as an indicator of thermal alteration

In the Beardmore Glacier region, Jurassic intrusions have altered the sediments of the Beacon Supergroup. Diabase (dolerite) sills and dikes ranging from 10 cm to 200 m in thickness have caused variable thermal alteration of the sedimentary sequence. Two major factors that control the severity of this alteration are the thickness of an intrusion and the proximity of a sample to that intrusion

(Jaeger, 1957; Jaeger, 1959). Other factors, including variable fluid migration, porosity differences in the sediment and compositional differences of the sediment, 88 may be important when coarse, permeable elastics are studied, but in this project these effects are held essentially constant by examining only the fine-grained clastic intervals.

Although exact values vary, several workers have suggested that the zone of severe alteration caused by an intrusion is less than twice the thickness of the intrusive body (Bostick, 1979; Dow and O’Connor, 1980). Work by Peters and others (1978) concluded that significant changes in organic matter were restricted to a much narrower zone than the above estimates would imply. Additional data from the Beardmore Glacier area are used to estimate the size of the zone of alteration near dolerite sills and dikes.

Sill thickness data and vitrinite reflectance values from eight measured sections are shown in Figure 24. These data have been separated so that the effects of overlying and underlying sills can be evaluated independently. For each section, the distance from each sample to the nearest overlying or underlying sill was measured. The thickness of the closest sill also was recorded, and the ratio of the sill-sample distance to the sill thickness was calculated. That ratio (sill-sample distance/sill thickness) is a normalized measure of proximity to the sill, and allows data from different sections to be compared. These data are limited to intrusions that are exposed at the surface, and do not exclude the possibility that there may be hidden intrusions below the ice or outcrop surface.

Results indicate that vitrinite reflectance values are high near the sills, and decrease rapidly with increasing distance from the sills (Figure 24). Samples that Figure 24: Summary of data from the Permian portion of the Beacon Supergroup Supergroup Beacon the of portion Permian the from data of Summary 24: Figure

Vitrinite Reflectance (Ro) generally decreases with increasing distance from the sill, and becomes becomes and sill, the from distance increasing with decreases generally to be a difference in the effects of underlying and overlying sills. overlying and underlying of effects appear the not in difference does a be There to thickness. sill one than greater at uniform relatively that compares vitrinite reflectance to proximity to sills. Vitrinite reflectance reflectance Vitrinite sills. to proximity to reflectance vitrinite compares that 0.0 0. 250 m overlying sill overlying m 250 0

0.5 100 m underlying sill 100underlying m t 200 m underlying sill underlying m 200 Distance from Sill/Sill Thickness Sill/Sill from Distance Ro vs. D istance/Sill Thickness Thickness istance/Sill D vs. Ro

Section MBO A Section CPZ CPZ Section A MBO Section Section MTR O Section MA6 A Section TGA TGA Section A MA6 Section O MTR Section 75 m underlying sill underlying m 75 Underlying and Overlying Sills Overlying and Underlying 1.0 75 m overlying sill overlying m 75 I Section MKR Section MMC Section MKR Section I 150 m underlying sill 150underlying m 1.5

2.0

2.5

3.0 25 m underlying sill underlying m 25 sill overlying m 20 "

3.5 Section—

4.0

4.5 MPI MPI

5.0

90 are farther than one sill thickness away from the sill have vitrinite reflectance values that do not vary significantly. This suggests that the effects of the nearby intrusive body are no longer important. Data points from different measured sections do not merge into a single curve beyond one sill thickness away from the sill, but instead occupy a limited range of vitrinite reflectance values. This reflects the differences in background heating levels between different parts of the study area. There does not appear to be a significant difference in the effect of underlying vs. overlying intrusive bodies. On the basis of these vitrinite reflectance data, the zone of significant alteration is proposed to extend one sill thickness away from a sill; samples located more than one sill thickness away from the sill are considered to be relatively unaltered.

Total organic carbon content as an indicator of thermal alteration

Relationships that were established using vitrinite reflectance can also be tested using T.O.C. data. The Mackellar Formation is ideally suited for a study of the alteration of organic carbon, because T.O.C. contents in unaltered measured sections from the Mackellar Formation appear to be fairly uniform (Homer, 1990).

This allows the relationship between T.O.C. content and distance from an intrusive body to be examined in the same manner as was done for the vitrinite reflectance data described above.

Although T.O.C. values in unaltered measured sections of the Mackellar

Formation appear to be relatively constant, there is no geologic reason that similar 91 internal uniformity should be true in most other clastic sedimentary deposits. The organic carbon input and preservational factors discussed above all combine to cause variations in the organic carbon content of sedimentary rocks. T.O.C. values are relatively constant in the Mackellar Formation because organic carbon input and the effects of depositional and preservational factors appear to have been relatively uniform. Minor fluctuations in T.O.C. values within the Mackellar Formation are interpreted to reflect minor changes in depositional and preservational factors. With this in mind, major variations in T.O.C. content that are controlled by proximity to an intrusive body are examined below.

A typical unaltered Mackellar section and the associated T.O.C. contents are illustrated by section CPZ (Figure 25). This is an example of a Mackellar section that lacks exposed intrusive bodies and has a relatively constant T.O.C. content. In contrast, the Mackellar Formation in sections TGA (Figure 26) and MMC

(Figure 27) contains overlying and underlying sills, respectively. T.O.C. content decreases near each intrusive body, with values that approach 0% T.O.C. near the thicker sills. These field data and T.O.C. measurements confirm the basic relationship between proximity to an intrusive body and degree of alteration of the surrounding sediments. Results from several thermally altered sections are now combined to examine the relationship between T.O.C. content and distance from an intrusive body.

Sill thicknesses and organic carbon distributions in six Mackellar sections are presented in Figure 28. Plots of T.O.C. vs. sill-sample distance/sill thickness Figure 25: Mackellar Formation, in section CPZ illustrating the relatively constant constant relatively the illustrating CPZ section in Formation, Mackellar 25: Figure Height in Section (meters) 200 190 130 . . present. Exclusively sampling the fine-grained beds removes variability due variability composition. or removes size beds grain to fine-grained the sampling not are Exclusively sills when present. Formation Mackellar the in content T.O.C. of nature Mackellar Formation Section CPZ Section Formation Mackellar 200 190 170 180 120 130 140 . - . . - - . .05 ecn Ognc Carbon Organic Percent .10 “ T .15 “ T .20 .25 i .30

.35 92 Figure 26: Mackellar Formation, in section TGA, illustrating the effect of an of effect theillustrating TGA, section inFormation, Mackellar 26: Figure

Height In Section (meter*) content toward the top of the section.the of top the toward content overlying sill on T.O.C. content. An overlying sill reduces the T.O.C. the reduces silloverlying An content.T.O.C. on silloverlying ..''V,. , v ' - i ,'." V '.•.i'.' ■ y, 0 *« o«(lg *111 ov«r(ylng m*t«r 50 Sy', Mackellar Formation Section TGA Section Formation Mackellar ' ‘ ecn Ognc Cartoon Organic Percent Figure 27: Mackellar Formation, in section MMC illustrating the effect of an of effect the illustrating MMC section in Formation, Mackellar 27: Figure

Height in Section (meters) 100 0 - 90 content toward the bottom of the section. The combined effects of the of effects combined The section. the of bottomthe toward content by the two individual sills. individual two the by caused alteration of sum the than greater is that sedimentsin surrounding alteration the cumulative a cause sills Multiple sill. lower the of thickness the times 1.5 to up for content T.O.C.the depress sills middle and lower underlying sill on T.O.C. content. An underlying sill reduces the T.O.C. T.O.C. the reduces sill underlying An content. T.O.C. on sill underlying . 5 M* udryn sill underlying iMI*r 25 19 akla Frain eto MMC Section Formation Mackellar / , / & //> > 100 120 110 90 80 50 . .5.5 2 .5 3 .35 .30 .25 .20 .15 .05 0.0 m m ecn Ognc Carbon Organic Percent 94 95

T.O.C. vs. Distance / Sill Thickness Underlying and Overlying Sills

200 m underlying sill

100 m overlying sill 20 m overlying sill

80 m overlying sill «a 0.3- 150 m underlying sill

£3 0 . 1- 75 m overlying sill

” 1— T T 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Distance from Sill/Sill Thickness

Section MMP Section CPZ Section MKR Section MMQ Section MMA Section MDK

Figure 28: Summary of Mackellar Formation data that compares T.O.C. content to proximity to a sill. Carbon content decreases rapidly at distances of less than one sill thickness. This criterion is used to identify altered vs. unaltered samples. There does not appear to be a significant difference between alteration by an underlying sill and alteration by an overlying sill. The effects of multiple sills are not considered in this diagram. 96 indicate that the zone of carbon alteration in this study is narrower than the zone of alteration reported by Bostick (1974) and Peters and others (1978). The most rapid decrease in organic carbon content occurs at distances of less than half the sill thickness, and many T.O.C. profiles reach a relatively constant value at distances greater than one sill thickness (Figure 28). The T.O.C. content at section MKR appears to decrease over a greater thickness, but this is caused by a wide sampling interval near the sill. On the basis of these data, the significant effect of heating on carbon contents is conservatively estimated to occur within one sill thickness adjacent to the sill. This provides a straightforward method for identifying altered and unaltered samples. It is interesting to note that there does not appear to be a significant difference in the effects of underlying vs. overlying intrusive bodies.

Instead, natural variations in T.O.C. content may mask any subtle differences in alteration intensity that are a result of the position of the intrusive bodies.

The effects of multiple intrusive bodies have not been considered in the preceding discussion. For example, the pattern observed in Section MMC

(Figure 27) is complicated by the presence of a thin (six meter thick) intermediate sill. The basal sill, which is 25 meters thick, depresses T.O.C. contents at the bottom of the section. T.O.C. contents then begin to rise as the effects of the basal sill become less severe, until the T.O.C. contents are depressed again by the intermediate sill. The combined effects of these two sills reduce the T.O.C. content in the bottom 30 to 40 m of the section, which is 1.2 to 1.6 times the thickness of 97 the underlying intrusive body. When more than one sill is present, the zone of

severe alteration is greater than the thickness of the intrusive body.

On the basis of this observation, the cumulative effects of multiple sills

appear to be greater than the additive effects of the individual sills. When two sills

are present, a conservative criterion of 1.5 times the sill thickness is used to

distinguish altered and unaltered samples. This relationship is tentative and should

be used with care, since differences in background heating level, thicknesses of the

intrusive bodies and order of intrusion will change the cumulative effects of multiple sills. Jaeger (1957, 1959) reached a similar conclusion with theoretical calculations by determining that pre-heating the country rock will dramatically

increase the size of the zone of alteration. The order of the intrusive events

becomes important in these calculations, because early intrusion of a large sill

would cause greater preheating of the country rock than early intrusion of a smaller sill. Estimates of these effects are beyond the scope of this study, but highlight the complicated effects of multiple intrusions. The general prediction of severe alteration of the country rock up to a distance of one sill thickness away from the intrusive body appears to be valid for sections that contain single intrusions, but care must be used in interpreting the severity and extent of alteration when multiple intrusions are present. 98 Organic carbon content in least-altered zones as an indicator of paleoenvironment and organic productivity

After determining the degree of alteration of each sample, the second step is to interpret the paleoenvironmental significance of the T.O.C. contents of relatively unaltered samples. This is accomplished by comparing mean T.O.C. contents on geographic and stratigraphic scales. Geographic variations are evaluated by examining mean T.O.C. contents for each measured section and comparing the results laterally. This analysis reveals no orderly variation for the T.O.C. contents from the Pagoda Formation, as might be expected in the homogenized glacial sediments. Mean T.O.C. contents from the Mackellar, Fairchild and Buckley

Formations are also generally homogeneous across the study area, although T.O.C. contents from section MBO are consistently higher than the within formation average. Conditions of deposition at section MBO appear to have either enhanced accumulation or favored preservation of organic carbon. Aside from the anomalous values at section MBO, there is little geologically significant geographic change in

T.O.C. content.

Since preservational effects appear to have been relatively uniform, large- scale variation in the mean T.O.C. content is interpreted to be related to changes in productivity during Carboniferous/Permian time. T.O.C. values are not direct measures of organic productivity, but in this study it is proposed that the T.O.C. values provide a general indication of changes in regional productivity during deposition of Beacon sediments. It is also important to realize that the T.O.C. 99 values do not stand alone as evidence for changes in depositional environment, productivity or paleoclimate. Instead, the interpretations presented here are based on the combination of lithologic descriptions, sedimentary structures, regional and stratigraphic relationships, and sediment compositions, which together provide a better understanding of environments at the time of deposition. Within this framework, the T.O.C. values of relatively unaltered samples are used to provide more information about productivity within the Permian environment.

On a smaller scale, T.O.C. contents can sometimes be used to provide a more complete description of the variety of local settings within the major depositional environments. Certain depositional environments have characteristic carbon contents, and identifying these conditions provides a more detailed view of

Permian deposition in the Beardmore Glacier region.

Organic carbon content, naleoenvironments. and productivity

Several widely separated localities along the paleo-Pacific margin of

Antarctica have stratigraphic successions that indicate climatic wanning during

Carboniferous/Permian time. Sedimentologic evidence for climatic change has been described in sediments of similar age from the Ellsworth Mountains, the Pensacola

Mountains and the Ohio Range (Elliot, 1975b; Collinson, 1990; Isbell, 1990).

These widely separated areas all contain basal glacial deposits that are overlain by coal-bearing fluvial deposits. The similarity of these successions indicates that climatic warming occurred over a large portion of Antarctica at that time. 100 In the Beardmore Glacier region, field-based sedimentologic and

paleontologic observations provide detailed evidence of the major climatic change

that occurred during Carboniferous/Permian time (Barrett and others, 1986; Miller

and others, 1987; Homer, 1990; Isbell, 1990). Glacial deposits of the Pagoda

Formation are overlain by the shallow basinal deposits of the Mackellar Formation

and, in turn, by the fluvial deposits of the Fairchild and Buckley formations. This

sequence records the decay of the Carboniferous/Permian ice sheet in the

Beardmore Glacier region. Within this stratigraphic framework, T.O.C. contents provide information about general productivity levels, and these interpretations are consistent with the general patterns of climatic change recorded in the

Carboniferous/Permian portion of the Victoria Group. Samples that were defined as

altered on the basis of their positions relative to intrusive bodies were removed from the data set prior to this phase of analysis. T.O.C. contents of the unaltered

fine-grained samples were averaged for each formation, and the results are

presented in Figure 29.

The 11 unaltered fine-grained samples from the Pagoda Formation have a mean T.O.C. content of 0.20%, with a standard deviation of 0.12%. These uniformly low T.O.C. values are distributed throughout several different Pagoda facies, and are consistent with deposition in a low productivity glacial setting with scarce vegetation and oxidizing conditions in the sediment. A portion of this organic carbon may be recycled material from pre-existing sedimentary rocks, although the amount of recycled carbon is difficult to determine. Thirty-nine 101

Average Total Organic Carbon (T.O.C.) Least-altered Beacon Supergroup Samples

lOOjg

n1n=11 II “In=39 | n=13 Pagoda Mackellar Fairchild Buckley Formation

Figure 29: Mean T.O.C. content in the four Carboniferous/Permian formations from the Victoria Group. Carbon content and the associated organic productivity increased as the Late Paleozoic ice sheet retreated. 102 unaltered shales and siltstones from the Mackellar Formation have a mean T.O.C. content of 0.33%, with a standard deviation of 0.12%. The mean T.O.C. content of the Mackellar Formation is slightly higher than that of the underlying glacial

Pagoda Formation, but the respective means lie within approximately one standard deviation of each other. Both units contain predominantly land-derived organic matter (Figure 22), and both units were probably deposited under oxidizing bottom conditions. Differences in the isotope geochemistry of concretions (Lord and others, 1988), suggest that productivity levels were less similar than these mean

T.O.C. values imply. Isotopic evidence from the concretions provides information about the sources of organic carbon in Pagoda and Mackellar sediments. 8l3C values in three calcitic concretions from the Pagoda Formation average +0.9 °/oa

(PDB), while the average 5l3C value for six calcitic concretions from the Mackellar

Formation is -9.4 VoofPDB) (Lord, 1986; Lord and others, 1988). The lack of 13C depletion in Pagoda calcite consistent with a lack of terrestrial vegetation during

Pagoda deposition, whereas the 13C depletion in Mackellar calcite indicates that carbon was derived from oxidation of biogenic compounds (Lord and others, 1988).

These results suggest that land vegetation was scarce and the supply of organic matter was correspondingly low while the Gondwana ice sheet was present. As the ice sheet subsequently retreated, land around the Mackellar basin became more vegetated.

In summary, productivity during Mackellar deposition was probably greater than productivity during Pagoda deposition, even though the resulting T.O.C. values 103 are similar. Possible explanations for the similarity in T.O.C. values are recycling of pre-existing organic carbon during deposition of the glacial Pagoda sediments, and dilution of organic carbon by high clastic influx during deposition of the deltaic

Mackellar sediments. An increase in alganitic carbon that occurred during deposition of the Mackellar Formation also contributed to the differences between the Pagoda and Mackellar Formations. The inferred increase in productivity was probably caused by climatic warming and early post-glacial dispersal of land plants in the Beardmore Glacier area.

Data from the Fairchild Formation are limited to four unaltered samples that have a mean T.O.C. content of 0.98% and a standard deviation of 1.06%

(Figure 29). Fine-grained floodplain deposits are rare in the Fairchild Formation, and their preservation is unusual because of the high degree of reworking in

Fairchild braided stream systems (Isbell, 1990). The small number of samples and an abnormally high T.O.C. value from section MBO are responsible for the high standard deviation. When section MBO is excluded, fine-grained Fairchild sediments have a mean T.O.C. content of 0.38%, which is very similar to the mean

T.O.C. that was calculated for the Mackellar Formation.

The Fairchild Formation is probably a lateral facies equivalent of the

Mackellar basinal deposits (Miller and others, 1987; Isbell, 1990), and many of the depositional conditions that were discussed for the Mackellar Formation also apply to the Fairchild Formation. Fairchild sediments were deposited in oxygenated fluvial environments, and the organic carbon was probably supplied by sparse, 104 opportunistic pioneer species that colonized the broad, flat braidplains of the

Fairchild braided stream systems, ,80 isotopic data from the Mackellar Formation suggest that abundant meltwater moved through these stream systems and into the nearby basin (Lord and others, 1988). The presence of meltwater in the contemporaneous Fairchild streams is a reminder that, although the

Carboniferous/Permian ice sheet had retreated, it may not have collapsed completely. The environment on the margins of the Mackellar basin was probably still variable and cool due to the effects of the decaying ice sheet

T.O.C. values from 13 relatively unaltered samples in the Buckley

Formation average 21.64%, with a standard deviation of 19.58% (Figure 29). High standard deviations of Buckley T.O.C. contents are caused by the presence of multiple fine-grained facies within the larger fluvial depositional environment. The transition from Fairchild to Buckley deposition is accompanied by a large increase in mean organic carbon content, which appears to record a significant short-term increase in productivity and preservation within the overall increase in productivity recorded by the Pagoda, Mackellar, Fairchild and Buckley Formations.

Evidence for increased productivity, enhanced preservation and a possible climatic change is supplied by the macroflora of Buckley deposits. Plant remains are common in Buckley sediments, in contrast to the older Beacon deposits. The density of fossil tree stumps on bedding planes in the Buckley Formation indicates that forests were present (Isbell, 1990; Taylor and others, 1992), and specialized

Vertebraria root traces from the Buckley Formation show that some of these plants 105 lived in swampy areas that bordered the Buckley stream systems (Schopf, 1983).

The latter observation suggests that preservation is an important factor in this

increased abundance of plant remains, since preservation of organic compounds is enhanced in anoxic swampy areas. As a result, increased productivity and

enhanced preservation combined to increase the T.O.C. content in Buckley sediments.

Organic carbon content and local depositional environments

The preceding section demonstrated the usefulness of combining T.O.C. data with field observations, paleontologic information and mineralogic data for interpreting large-scale paleoenvironmental and productivity patterns. Localized facies relations also can be clarified by mapping organic carbon abundance (Dow,

1977; Schultz and others, 1980) or by examining organic carbon abundances within

individual sections or outcrops. This approach is especially useful in the Buckley

Formation, where fine-grained sediments were deposited in a variety of facies within the fluvial environment.

Facies distinctions using T.O.C. content are of limited use in the Pagoda,

Mackellar and Fairchild Formations for a variety of reasons. Fine-grained sediments from the Pagoda Formation were deposited in meltout ponds, stream overbank environments or proglacial lakes, but exhibit little variation in T.O.C. content between these environments. In the Mackellar Formation, the T.O.C. contents of the fine-grained facies are relatively uniform. Fine-grained sediments 106 from the Fairchild Formation were not preserved in sufficient abundance to allow any facies distinctions on the basis of T.O.C. content.

In the Buckley Formation, several fine-grained facies can be distinguished using a combination of T.O.C. values and field observations. These facies are found in floodplain settings that bordered the Buckley stream system. In some cases, the T.O.C. content alone allows the specific environment or facies to be characterized. In other cases, the combination of T.O.C. content and field relations must be used to determine the depositional environment.

Coals from the Buckley Formation have distinctive carbon values that range from 40.52% to 58.05%. Low oxygen contents and low clastic sedimentation rates enhance the preservation of organic matter in this group of sediments. Coal beds are an example of a facies that can be characterized by T.O.C. content, although field identification is usually the primary means for recognizing coals. High T.O.C. values are used as supplemental evidence to confirm the environmental interpretations that were derived from field relationships, lithologies and sedimentary structures.

A second distinct group of fine-grained Buckley samples is composed of shale with rare silty shale laminae and carbon contents that range from 13.3% to

37.7% T.O.C. These are interpreted as shallow pond deposits, with low oxygen conditions and sporadic clastic input. The increased importance of clastic material and the presence of rare silt laminae distinguish the pond sediments from the peat- forming deposits described above. In some cases, organic-rich pond deposits grade 107 into the sediments of the peat-forming environments, and, in these cases, the two facies cannot be distinguished on the basis of T.O.C. content alone.

The third group of fine-grained Buckley samples is composed of shale or interbedded siltstone and shale, with T.O.C. values that range from 0.2% to 12.7%

T.O.C. This group of samples includes several different types of floodplain facies that cannot be distinguished solely on the basis of their T.O.C. content. Instead, specific sedimentary structures or lithologic associations must be used in conjunction with T.O.C. content to identify facies. Paleosols are identified by the presence of plant debris and rooted horizons. Overbank deposits can be distinguished by the presence of mudcracks. Large-scale scours that are infilled with fine-grained sediment are interpreted as channel fill deposits. In these examples, the T.O.C. content does not distinguish the various depositional environments, because the T.O.C. contents of paleosols, overbank deposits and channel fill deposits overlap. T.O.C. contents of floodplain facies and the ponded facies also overlap to some extent, but the associated sedimentary structures differentiate these major facies groupings.

Analysis of organic carbon contents distinguishes certain facies on the basis of their organic carbon contents, and provides additional understanding about the range of conditions within a depositional system when the T.O.C. contents are combined with stratigraphic data, sedimentary features, paleontologic information and mineralogic analysis. T.O.C. content is most useful as an environmental 108 indicator in the flnvial sediments of the Buckley Formation, where several distinctive facies were deposited within the braided stream setting.

Summary

Several factors have the potential to affect T.O.C. abundances in Beacon sediments. Sedimentation rates, grain size differences, types of organic matter present, recycling of pre-existing carbon, bioturbation, dissolved oxygen content, thermal alteration and variations in primary productivity have all been considered as possible causes for the observed differences in T.O.C. content. Of these factors, thermal alteration and variations in primary productivity are identified as the variables which most often control the T.O.C. content. The severity of thermal alteration is estimated by combining field measurements of sill thickness with laboratory measurements of vitrinite reflectance and organic carbon content. This analysis indicates that significant alteration of organic carbon is limited to a zone approximately one sill thickness away from the sill contact.

With alteration patterns established, relatively unaltered samples are used for provenance and paleoclimatic determinations. Kerogen typing and C/S ratios indicate that the source of organic compounds is dominantly terrestrial, and that there is no evidence for marine influence even during deposition of the Mackellar deltaic sediments. This conclusion contrasts with evidence from other areas of the

Transantarctic Mountains and the Karoo Basin, where trace fossils have been used to infer a marine origin for Mackellar equivalents (Collinson, 1990). Kerogen 109 typing also provides some clues about the types of plant life that existed during

Mackellar deposition, and suggests that a flora of simple algae were able to survive in the Mackellar Basin.

Inferences about Permian paleoclimate and productivity are gleaned from facies analysis and mean T.O.C. distributions. The average T.O.C. content of relatively unaltered samples in each formation has been used in combination with other sedimentologic parameters to interpret paleoenvironments, productivity changes and facies distributions within the Carboniferous/ Permian portion of the

Victoria Group. The results for the fine-grained facies of each formation are summarized below:

• Pagoda Formation: Mean T.O.C. content of 0.20%, with relatively

uniform regional distribution.

• Mackellar Formation: Mean T.O.C. content of 0.33%, with relatively

uniform regional distribution. T.O.C. contents from section MBO

(extreme southern end of field area) are anomalously high.

• Fairchild Formation: Mean T.O.C. content of 0.98%, with moderate

regional variability and an abnormally high T.O.C. content in the

southern portion of the study area (section MBO).

• Buckley Formation: Mean T.O.C. content of 21.64%, although T.O.C.

content varies widely due to the presence of multiple facies within

the fluvial depositional environment. Swamp, pond and floodplain 110 deposits each have a distinctive carbon content that aids in the

characterization of the facies.

Paleoenvironmental interpretations are made in the Permian portion of the

Beacon Supergroup using evidence from field relationships, sedimentary structures,

lithologic descriptions, total organic carbon analysis, kerogen typing and carbon and

oxygen isotopes. This combined data allows conclusions to be drawn that go

beyond the determination of depositional environments, and provides information about the productivity and during Permian time. In the

Beardmore glacier area, climatic wanning during the retreat of the

Carboniferous/Permian ice sheet triggered an increase in the general level of terrestrial productivity, and this change is reflected in the carbon content of the sediments. The transition from the low productivity glacial environment of the

Pagoda Formation to the temperate, humid environment of the Buckley Formation is recorded clearly in these upper Paleozoic sediments. CHAPTER IV

SEDIMENTARY GEOCHEMISTRY

Introduction

The study of inorganic geochemistry in mudrocks from the Beardmore

Glacier region is part of a larger project that incorporates geochemistry, mineralogy and field relationships to describe the depositional environments, diagenesis, i mineralogy, paleoclimatic signatures and provenance of fine-grained Permian elastics from the Beardmore Glacier region (Homer and Krissek, in press; Homer and Krissek, 1991; Krissek and Homer, 1986; Krissek and Homer, 1987; Krissek and Homer, 1991). In this chapter, inorganic geochemical data are used to contribute to our understanding of the paleoclimatic, provenance and diagenetic histories of Permian mudrocks. Included are a brief description of the methods used to obtain inorganic geochemical data, a discussion of the factors that affect mudrock chemistry, results of major, minor, trace and rare earth element analyses, an analysis of the reproducibility of these data, and a discussion of numerical and statistical relationships within the geochemical data set. These results are then interpreted with reference to changes in source area, differences in climatic conditions and the effects of diagenetic or thermal processes.

I l l 112 Approach to Interpretation

Several factors control the chemical composition of fine-grained sediments,

and the importance of each of these factors must be assessed before interpretations

are made concerning paleoclimatic signatures and provenance of Permian mudrocks

in the Beardmore Glacier area. Factors that can affect the chemical composition of

mudrocks include the following:

• thermal and diagenetic alteration

• preferential association of elements with organic carbon

• mineralogic effects, including grain size

• depositional processes, including transport and redeposition

• paleoclimate

• provenance

Bulk geochemical data are used to examine the importance of these variables, and when secondary chemical controls have been identified, allow informed interpretations to be made about paleoclimate and provenance during Permian time.

Diagenetic and thermal alteration as controls on mudrock geochemistry

Major and minor element distributions in sedimentary rocks are subject to diagenetic and thermally induced changes that alter the bulk chemical composition.

Several of the diagenetic and thermal factors that influence sediment chemistry are examined here using graphical comparisons of element abundances. Sandstones from the Beardmore Glacier region commonly exhibit diagenetic effects that 113 include feldspar dissolution, cementation with clay minerals or quartz and the formation of zeolites (Vavra, 1984; Vavra, 1989; Barrett and others, 1986; Isbell,

1990). These diagenetic effects commonly alter the major element chemistry, and may alter the bulk chemical composition of the rock. Previous work with minor element distribution in mudrocks has demonstrated that metals may be mobilized by diagenetic or epigenetic fluids, as evidenced by mineralization of deep sea shales and hydrothermal ore bodies (Vine and Tourtelot, 1970; Horowitz and Cronan,

1976; Holland, 1979). Diagenetic and thermal alteration are potential causes of element mobility, and may alter the bulk geochemical composition of mudrocks.

Thermal alteration is assumed to have a greater effect than diagenetic alteration, since thermal alteration exceeded 400° C and may have approached 600° C

(Chapter ID), while diagenetic effects are restricted to near-surface temperatures and pressures. Although this assumption will be used for the remainder of the study, it is important to note that pore fluid composition was probably different between diagenetic and thermal reactions, and the effects of changes in pore fluid cannot be dismissed. In spite of this potential difference, it is assumed that the higher temperatures and pressures associated with thermal alteration have a greater effect on the sediment chemistry than diagenetic reactions. For this reason, elements that are identified as immobile during thermal alteration are assumed to be relatively immobile during the lower temperature diagenetic alteration.

The effect of secondary thermal alteration is here examined by plotting either distance from intrusive bodies or vitrinite reflectance against the abundance 114 of major and minor elemental constituents. Both distance from intrusive bodies and vitrinite reflectance are used to indicate the intensity of the alteration. Elemental abundances in this and many succeeding plots are normalized to correct for high carbon content, since elemental abundances in the coaly samples have been lowered due to a dilution effect by organic carbon.

Normalization of elemental abundances to account for high carbon content is accomplished by summing the abundances of the major elements and setting that sum equal to 100%. Proportions of individual elements within that sum can then be calculated. Minor and rare earth elements are also restored to carbon-free abundance values by applying the same correction factor to raw data values. When the effects of high carbon content are removed, corrected elemental abundances are examined for trends that are related to secondary thermal alteration in these sediments.

Organic carbon content as a control on mudrock geochemistry

Complexing of metallic cations with organic carbon is another common cause of chemical variation in mudrocks (Hirst, 1962; Vine and Tourtelot, 1970;

Spears and Amin, 1981) and this effect is examined here by plotting organic carbon content against elemental abundances that have not been normalized. Studies of metal-rich black shales have identified a positive correlation between organic carbon content and minor element abundance (Tourtelot, 1964; Sholkovitz, 1978;

Spears and Amin, 1981), and work with modem plants has identified a group of 115 elements that are necessary for plant nutrition (Salisbury and Ross, 1992). If complexing of metallic cations with organic carbon is a significant factor in the observed chemical distribution, there should be a correlation between carbon content and the abundance of that element. The relationship between organic carbon and elemental abundance is given special consideration in the Buckley

Formation, where nutrient uptake by an emergent vegetative cover may have altered the chemical composition of the sediments.

Mineralogy and grain size as controls on mudrock geochemistry

Mineralogy and grain size have a strong influence on major, minor and rare earth element distributions in sedimentary rocks. A correlation has been observed between minor element abundance and clay mineral distribution (Dixon and Weed,

1977; Tuttle and others, 1983), and quartz and feldspar concentrations which have an influence on bulk geochemistry are known to vary according to distance from the detrital source area (Blatt and Totten, 1981). Minor elements substitute into the framework of silicate and phyllosilicate minerals, and also occur as charge- balancing cations in the interlayers of clay minerals. These mineralogic and grain size effects commonly act as the controlling factor in major and minor element distribution in fine-grained elastics (Hirst, 1962; Cody, 1971).

Complete mineralogic analyses are presented in the following chapter, but in this section Si02, A1203 and Fe203 are used as indirect evidence of the mineralogy.

Si02 content is related to quartz abundance and generally indicates coarser grain 116 size, while A1203 and Fe203 abundance in mudrocks is controlled by the presence of aluminosilicate (clay) minerals and generally indicates a liner grain size.

Aluminum content is related to the abundance of illite and chlorite (see chapter V), while iron content is related to an abundance of iron in the mineral chlorite. Since

Si02, A1203 and FejO, concentrations are clearly tied to changes in grain size and mineralogy, they are used as a standard to which other elemental abundances are compared. A positive correlation between one of these elements and an element of

unknown affinity is interpreted to record a grain size or mineralogic effect The effects of changing mineralogy and grain size are mirrored in the chemical composition of the mudrocks, and the extent of this control on other elements is examined using the methods described above.

Sedimentoloeic controls on mudrock geochemistry

Differences in sedimentary processes, including transportation and deposition of the sediment, are also potential causes for variations in sediment chemistry, and these factors must be examined as potential controls on the chemistry of Beacon sediments. Weathering and sedimentologic effects are difficult to identify solely on the basis of bulk chemical composition, but a comparison of known mechanisms of deposition for the four formations studied limits the number of processes that must be considered. Organic carbon distribution and 8‘®0 isotopic values (see Chapter

III) suggest that the Carboniferous(?)/Permian ice sheet exerted climatic control over the study area during deposition of the Pagoda, Mackellar and Fairchild 117 Formations. Mechanisms of weathering are related to climatic conditions, so weathering conditions may have been similar during deposition of the lower units.

This concept will be discussed in greater detail in the next section.

Another similarity between two of the formations studied is their mode of transport and deposition. Modes of transport and deposition were similar for the braided stream deposits of the Fairchild and Buckley Formations, and if mode of transport and deposition is a controlling factor in sediment chemistry, the Fairchild and Buckley Formations should have similar chemical patterns.

Chemical relationships between the group of samples with similar weathering patterns and the group of samples with similar depositional environments can now be compared. Large differences in chemistry between either of these groups may be attributed to changes in weathering or mode of sediment transport, but differences within these groups are assumed to be more directly controlled by factors other than weathering, mode of transport or depositional environment.

Paleoclimate and provenance as controls on mudrock chemistry

After the variables discussed above as potential controls of bulk sediment chemistry have been examined and their effects have been evaluated, remaining patterns can be attributed to changes in provenance or paleoclimate. Several theories regarding elemental distributions in different tectonic regimes will be tested using data from the Beardmore Glacier area. Sediment supply during deposition of 118 the Pagoda, Mackellar and Fairchild formations was from the Antarctic craton, and should reflect the chemistry of the Archean basement, Archean to Proterozoic metasediments, and lower Paleozoic sediments described by Gunner (1983).

Previous work has identified a calc-alkaline volcanic influx during deposition of

Buckley Formation sandstones (Barrett and others, 1986), and contemporaneous^) volcanic influx is postulated as the source for the volcaniclastic sediment

(Collinson, 1990). Elemental abundance ratios, calculated from the geochemical data of this study, are well suited for determining the timing of the volcanic input and identifying chemical differences resulting from these changes in tectonic setting. Elemental abundance data from four airfall tuffs in the Falla Formation are averaged from Barrett and others (1986), and these data are plotted on graphs of elemental abundance ratios from the Pagoda, Mackellar, Fairchild and Buckley

Formations to determine whether the chemistry of the interpreted volcanic influx is similar to the chemistry of known volcaniclastic sediments.

Several approaches are used here to identify changes in source area and sediment supply using the geochemical data. Graphs of Si02, A120 3 and Fe203 vs. element abundance (described previously as a way to evaluate the effects of sediment grain size) provide basic information about stratigraphic changes in bulk chemistry. Stratigraphic and geographic patterns are also examined using A1203 to

TiOz ratios that identify the mafic or felsic nature of the source material.

Al20/T i0 2 ratios are high when the source for the sediment is felsic and low when the source area has a mafic composition (Nesbitt, 1979). Si(yA l203 ratios are 119 plotted with similar intent, since Si02 is more abundant in felsic or cratonic source

areas, while A1 occurs in greater relative abundance in mafic source areas (Bhatia,

1983; Roser and Korsch, 1988). Another chemical provenance tool is applied by

plotting the K20/Naj0 ratios of Schwab (1985), with the idea that the KjO/NajO

ratio is highest along stable continental margins, and decreases near Andean and

Pacific type volcanic margins. This ratio is designed to give an indication of the

degree of differentiation of the parent material, since highly differentiated and

recycled crustal sediments are rich in K, while less differentiated magmas with

deeper crustal origin contain more Ca and Na. The elements used in this ratio are

essentially an indicator of feldspar composition, so a modified Schwab analysis

using the ratio of K^O/CCaO+NajO) is also examined in this paper in an attempt to

identify changes in ratios of potassium and plagioclase feldspar content.

Climatic effects on major element chemistry are examined using ratios of

major elements that have different susceptibilities to weathering. The

Carboniferous(?)/Permian deglaciation of Antarctica is well established (Frakes and

others, 1971), and the effect of climatic warming on mudrock chemistry has been

studied by Nesbitt and Young (1982). Chemical weathering prior to erosion and

deposition of sedimentary particles causes leaching of the major elements, and this

change is reflected in the chemistry of the resulting sedimentary rocks. Changes in ratios of major element abundances over an entire region have been used to

interpret changing climatic conditions in the geologic past (Nesbitt and Young,

1982; Hamois, 1988; Viser and Young, 1990). Plots of Nesbitt and Young’s 120 chemical index of alteration (C.I.A.) use molar proportions of the major elements in

the following formula: C.I.A. = [A1203 / (A1203 + CaO + NajO + K20)] to examine the extent of major element removal during chemical weathering. These principles are applied in the Beardmore Glacier region, where ratios of major element abundances in Permian sediments are plotted to examine changes in provenance or paleoclimate that are expressed as changes in the bulk chemistry.

Multivariate statistical methods and analysis of mudrock chemistry

After simple statistical and graphical methods have been used to identify the controls on bulk sediment chemistry, multivariate statistical methods are used to examine the entire data set for additional trends and patterns. Four relationships are established through multivariate statistical analyses of these geochemical data. The first relationship is obtained through cluster analysis, which describes groupings of generally similar samples within the data set. The second relationship identifies the variables that are responsible for the similarity groupings. The third identifies the specific variables responsible for compositional similarity after the effect of a major dilutant (organic carbon) is removed, and the fourth compares elemental associations in altered and unaltered samples to evaluate elemental mobility during diagenesis.

Results from chemical analyses were subjected to cluster analysis and principal component analysis using the SAS statistical package (SAS Institute,

1988) on Ohio State's mainframe IBM computer. Cluster analysis describes 121 groupings of generally similar samples within the data set, thereby identifying samples that have similar chemical compositions (Davis, 1986). A SAS procedure called Ward’s method of hierarchical clustering is used to group related samples into clusters. Ward’s method starts by generating an n x n similarity matrix, and calculates euclidean distances between each sample. Clustering proceeds by progressively joining clusters with the highest similarity (lowest euclidean distance).

Each time a sample is joined to a cluster the similarity matrix is recalculated. This procedure continues until the two clusters with the least similarity are joined and the analysis is complete.

Cluster analysis is a powerful tool for identifying groups of similar samples, but it does not identify the individual elements (variables) that are responsible for the similarities or differences between groups of samples. For this reason, principal component analysis was used to identify elements or groups of elements that co- vary within the data set, with the objective of determining the causes of the similarity identified by cluster analysis. The mathematical basis of the analysis is the extraction of eigenvectors from an n x n correlation matrix, so that each principal component (eigenvector) identifies a group of variables that co-vary

(Davis, 1986), The importance of each variable (element) in a particular principal component is indicated by its "loading" on that component. A large positive or a large negative value indicates that the variable covaries strongly with that group of variables, whereas a value near zero indicates that the variable varies independently of that group. A "score" is also calculated for each sample for each principal 122 component, and describes the characteristics of that sample relative to the extreme values for that principal component. In this study, both the principal components and the scores have potential geologic significance as follows: 1) each principal component defines an association of co-varying elements, which can be interpreted in terms of geologically reasonable solid phases, perhaps supplied by distinctive processes or from distinctive sources; and 2) the geographic and/or stratigraphic distribution of "scores" for a principal component can be used to identify the source areas and/or processes responsible for supplying that phase.

Methods

Steps in generating the geochemical data include field sampling, sample preparation, elemental analysis and statistical analysis of the geochemical data.

Each phase of the analysis requires different methods of sample handling and treatment of the data. Potential contamination of the samples and uncertainty in the reproducibility of the data also vary depending on the analytical method employed.

The methods used and the steps taken to ensure the integrity of each process are discussed below.

Field sampling and sample preparation

Special care was taken to avoid contaminating the samples during each phase of sample collection and preparation. Contamination by surficial weathering was minimized by avoiding weathered surfaces and quarrying the samples from 123 fresh rock outcrops. Weathering alters the major element chemistry, since some major elements are mobilized during chemical weathering of silicate minerals

(Nesbitt and Young, 1982). This surficial (recent) chemical weathering is less important in Antarctica than in many field areas, because Antarctica’s cold climate inhibits leaching and chemical weathering.

Contamination is a special problem when minor and rare earth elements are analyzed, since very small amounts of metallic debris from a rock hammer, a sieve or a steel crushing mill may introduce relatively large concentrations of minor or rare earth elements to the sample (Reeves and Brooks, 1978). Contamination by introduced trace metals was minimized during sample preparation by crushing the samples in a burlap bag (to avoid contact with a rock hammer) and grinding in an agate mill (to avoid potential contamination from a tungsten carbide ball mill).

These precautions ensure that contamination was minimized during sampling and sample preparation, and that the resulting elemental data reflect the chemistry of the original rock.

Elemental Analysis

As part of the larger project, 90 whole rock samples were selected from the

310 samples collected during field work, and were analyzed for major, minor, trace and rare earth element abundances. The inorganic chemical analyses used in this study were performed by a well-known commercial laboratory (XRAL X-Ray

Assay Laboratories), which used X-ray fluorescence (XRF), direct coupled plasma 124 emission spectroscopy (DCP) and instrumental neutron activation analysis (INAA)

to analyze for 44 major, minor and rare-earth elements. Sample preparation,

analytical equipment and reproducibility are different for each method of analysis.

Information about each method is summarized below, and results of precision,

accuracy and reproducibility tests are summarized in Appendix B.

Major Element Analysis by XRF

Major elements are typically defined as elements that make up greater than

one percent of the earth’s crust, or elements that comprise more than five percent of

a rock. In geologic settings, major elements are the chemical constituents that form

the common rock-forming minerals. The eight major elements analyzed in this

project are Si, Al, Ca, Na, K, P, Fe and Mg.

The major elements Si, Al, Ca, Na, K, P, Fe, Mg and minor elements Mn

and Ti were analyzed by whole rock XRF, and results are reported as a weight

percent of the oxide. XRAL begins the analysis by fusing 1.3 gm of powdered

sample with 5 gm of lithium tetraborate, and casting the molten material into a

button. Samples are analyzed on a Phillips PW1600 simultaneous x-ray

fluorescence spectrometer that uses an x-ray beam to excite the sample, causing

ionization of orbital electrons. As the electrons decay from the excited state, they

emit fluorescent x-rays that have energies characteristic of the element analyzed

(Potts, 1987). A spectrometer with fixed channels for each major element measures the energy of the emitted x-ray photons, and a processor corrects for matrix effects 125 and converts to abundance values. The spectrometer is calibrated using a series of

reference standards including samples from the United States Geological Survey,

the U.S. National Bureau of Standards, and Canadian, British, French and South

African reference materials. Following the analysis, major elements and loss on

ignition (LOI) are summed to check the accuracy of the run. Results from tests of

precision, accuracy and reproducibility of major element analysis using XRF are

presented in Appendix B.

Minor Element Analysis by DCP

The definitions of a "minor element" and a "trace element" vary (Reeves

and Brooks, 1978), and the terms are commonly used synonymously. Because of

this overlap in terminology, no further distinction will be made between minor and

trace elements, and this group of elements will be referred to as "minor elements."

Minor elements are elements that occur in low abundances, either by substitution

(camouflage, capture or admission) into the crystal lattice of a mineral component, or as adsorbed charge-balancing cations, commonly in the interlayers of clay minerals (Faure, 1991). The minor elements Be, B, Sc, Ti, V, Cr, Mn, Co, Ni, Cu,

Zn, Ge, As, Se, Br, Mo, Ag, Cd, Sb, Cs, Hf, Ta, W, Ir, Au, Pb, Th, U, were analyzed in this study using two different analytical methods.

The minor elements Be, B, V, Ni, Cu, Zn, Ge, Ag, Cd and Pb were analyzed by XRAL Laboratories using direct current plasma-optical spectrometry

(DCP). Prior to the analysis, samples are digested in a series of nitric and 126 hydrochloric acid baths to dissolve the silicate component and concentrate the elemental constituents in an aqueous medium. DCP uses an electrical discharge between three electrodes to generate a direct current plasma in an argon gas stream

(Potts, 1987). Samples are nebulized and sprayed into the plasma cloud, causing volatilization and then atomization of the aerosol droplets. The emission spectra of excited atoms is collected by a spectrometer, and characteristic emission lines are resolved for each of the elements analyzed. Reproducibility tests from these analyses appear in Appendix B.

Minor and Rare-Earth Element Analysis by INAA

The rare earth elements (REE) are members of group nia of the periodic table, and include elements with atomic numbers that range from 57-71. Rare earth elements require special consideration during elemental analysis because of their chemical similarity, fractionation properties and low crustal abundances. They are generally considered to be immobile (Bhatia, 1985), and this property makes them useful for provenance determinations in altered sedimentary units. The rare earth elements La, Ce, Nd, Sm, Eu, Tb, Yb and Lu were analyzed in this study. Since this project concentrates on fine-grained elastics, the North American Shale

Composite (NASC) is used as the standard for comparison of rare earth element abundances (Gromet and others, 1984).

The remainder of the minor and rare earth elements studied in this project

(Au, Sc, Cr, Co, As, Se, Br, Mo, Sb, Cs, La, Ce, Nd, Sm, Eu, Tb, Yb, Lu, Hf, Ta, 127 W, Ir, Th and U) were analyzed by XRAL Laboratories using instrumental neutron activation analysis (INAA). In this method, samples are bombarded by neutrons, creating short-lived unstable radioactive isotopes. The decay of these isotopes is monitored over time, and specific isotopes are identified and quantified by their emitted gamma-ray energy (Potts, 1987). XRAL uses the 2 MW nuclear reactor at

McMaster University as a neutron source, and irradiates the samples for 1 hour at a thermal neutron flux of 7 x 1012 n/cm2/sec. A standard is irradiated and counted with each batch of samples to calibrate each sample run, and after approximately 7 days the emitted gamma ray spectra are measured using a high resolution germanium gamma ray detector. Results are quantified by comparing the characteristic gamma ray emission of specific isotopes in the sample to the emission pattern in the standard. Two or more emission spectra are measured for each element, and after 1 to 5 additional days, approximately 30% of the samples are recounted to check the accuracy of the run (XRAL in-house report for clients).

Summaries of precision, accuracy and reproducibility are given in Appendix B.

Results and discussion

Complete results of elemental analysis are presented in Appendix B. Mean elemental abundances and standard deviations from the mean are calculated for informal subdivisions of the Permian formations, and composite means and standard deviations are also calculated for each formation. This data set is also used to generate all simple elemental ratios and is subjected to multivariate statistical 128 analysis. Major element analyses from airfall tuff samples KO20, K023, F220 and

F247 are averaged from Barrett and others (1986), and these results are plotted on several graphs to provide a comparison of the composition of Permian sediments and Triassic/Jurassic volcaniclastic units.

Results of analysis of factors that control mudrock chemistry

Alteration, preferential association of elements with organic carbon, mineralogic and grain size effects, paleoclimate and provenance are potential controls of mudrock chemistry. These factors are analyzed individually using bulk geochemical data, and the results are presented below.

Thermal alteration as a control on mudrock geochemistry

Secondary mobilization of chemical components is a potential control on the chemical composition of mudrocks. Element mobility during thermal alteration was examined here by plotting vitrinite reflectance values against normalized elemental abundances. Results from Chapter m (Figure 24) established that vitrinite reflectance is affected by thermal alteration, and identified several stratigraphic sections where this relationship is clear. Six of the stratigraphic sections that were examined in Chapter in are now used with representative major, minor and rare- earth elements to illustrate the relationships between thermal alteration and variations in elemental abundance. Samples from each stratigraphic section are plotted in order of increasing distance from the intrusive body. If element 129 distributions are affected by the thermal event, there should be a correlation between vitrinite reflectance and chemical composition. If the element in question is unaffected by thermal alteration, it will vary randomly on these diagrams.

The majority of the elements studied show little correlation between vitrinite reflectance values and elemental abundance as samples are collected closer and closer to intrusive bodies (Appendix B). Examples of this random distribution are shown in Figure 30, where the representative elements Si02 and K20 are plotted against vitrinite reflectance values. The random distributions shown on these graphs are interpreted to reflect a lack of chemical mobility, and indicate that most elements have not participated in significant chemical exchange between the sills and the sediments. It is also conceivable that some elements were removed from the system by hot hydrothermal fluids, and deposited outside of the Ethologies or stratigraphic units included in this study. This is an unlikely scenario, since thermal alteration varies from non-existent to severe (low temperature metamorphism), but there is little observable chemical difference between the least altered and highly altered samples.

Although most sections and most elements do not show a correlation between elemental abundances and extent of alteration, sections MTR and MPI show a slight positive correlation between the abundances of Fe, Mg, Mn and Na and vitrinite reflectance values (Figure 31; Appendix B). There is natural variation in elemental abundances due to differences in grain size, but the effects of proximity to an intrusive body are also evident. For this type of analysis, it would 7.0 2 std. dev. 6.0- Mean Si02 <2 abundance, IT 50‘ dolerite sills | 4.0- o Gu rt 3.0 a>

2.0- I> 1.0 -

0.0 Si02 (normalized %) 7.0 2 std. dev. 6.0- Mean k 2o 5.0- abundance, dolerite sills o 4.0 e £ 3.0- 4>

2. 0 - > 1.0-

0.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 K20 (normalized %) Section MKR - A - Section CPZ — Section MPI —b — Section MTR >< Section TGA —<— Section MBO

Figure 30: Comparison of vitrinite reflectance vs. Si02 and K20. There is a lack of correlation between vitrinite reflectance values and the abundance of most major, minor, and rare-earth elements. Error bars for the elemental abundances on this and succeeding graphs are displayed as a single horizontal line that is two standard deviations wide, and are obtained from five replicate runs of sample MTM 269.0 (Appendix B), 7.0 2 std. dev. Mean Fe203 6. 0 - abundance, dolerite sills 5.0- 8 U 4.0- 9> Gu OC 3.0 u I 2.0- > 1.0-

0.0 Fe203 (normalized %)

7.0 2 std. dev. Mean MgO abundance in 6. 0- dolerite sills = 6.5% „ 5.0-

3.0-

M 2. 0 - > l.o-

0.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 MgO (normalized %) Section MKR -A - Section CPZ — Section MPI - a - Section MTR -»«— Section TGA — Section MBO

Figure 31: Comparison of vitrinite reflectance values vs. F e ^ and MgO values from selected stratigraphic sections. Sections MTR and MPI show a positive correlation between increasing alteration and increasing abundance of iron and magnesium. This implies that the intrusive body contributes iron and magnesium to the sediment. 132 have been preferable to examine the sediment chemistry within one bed, and monitor the changes in chemical composition that occur with proximity to a dike.

This strategy would have eliminated many of the grain size and compositional differences that are responsible for the observed variability. Since this sampling strategy was not employed during fieldwork, evaluation of the geochemical data will continue to rely on vertical distribution of the elements with proximity to sills.

Low initial concentrations of Fe, Mg, Mn and Na in the Buckley Formation and mobility of these elements during thermal alteration are interpreted to be responsible for the patterns observed in sections MTR and MPI. Both of these sections contain samples that are exclusively from the Buckley Formation, and the

Buckley Formation has substantially less Fe, Mg, Mn and Na than the underlying units (Appendix B). As the extent of alteration increases, the concentration of these elements increases. This is interpreted to result from a contribution of chemical components to the sediment from the intrusive body, pulling the chemical composition of the sediment toward the composition of the intrusion. Mean chemical composition of the intrusive bodies is plotted on the graphs when these data are available (Faure and others, 1990), and for the representative elements shown in this section, increasing alteration appears to be related to higher Fe, Mg,

Mn and Na contents in sections MTR and MPI (Figure 31; Appendix B). Sections

MTR and MPI may be particularly susceptible to alteration because they are located in the highly altered central region of the study area (see Chapter III), and are underlain or overlain by sills ranging from 100 to 200 m thick. 133 A second method of examining the extent of chemical mobility caused by thermal alteration is to plot elemental abundance vs. distance from the intrusive body (Appendix B). On these graphs, sill thickness is normalized by dividing distance from the sill by the sill thickness. This allows comparison of chemical relationships between stratigraphic sections that contain sills of varying thickness.

An empty vertical corridor at the left side of the graphs represents the intrusive body, and mean chemical compositions of dolerite sills from the Beardmore Glacier region (when available from Faure and others, 1990) are plotted as a horizontal line. A strong correlation on the graph appears as a linear increase or decrease in elemental abundance within a given section as the intrusive body is approached.

Results produced by these analysis are similar to results obtained when vitrinite reflectance is used as an indicator of alteration. Most major, minor and rare-earth elements are unaffected by proximity to intrusive bodies (Appendix B).

Si02 and K20 are examples of elements that do not show a correlation between elemental abundance and proximity to an intrusive body (Figure 32). These results are again interpreted to represent a lack of large-scale chemical mobility, and appear to be consistent for representative major elements (Si02, A120 3, K20, CaO,

P2Os and T i02), high field strength metals (Hf and Th), transition metals (Sc and

Zn) and rare earth elements (La and Lu). A few elements from Buckley samples at sections MPI and MTR appear to have been mobilized in samples collected in close proximity to the sills. Sections MBO, CPZ and TGA also show weak trends toward high metal abundances in close proximity to intrusive bodies. Fe203, MgO, 90-

^ 85 $ T3 80 % « 75- i-E Bo 70- 65- ^ g 0. I 2 std. dev. Mean Si02 abundance, 55- f dolerite sills

Distance from Sill/Sill Thickness 6.5

5.5-

•o 4.5- 13Ji | 3.5- o

O 2.5- 2 Mean K 20 ^ I 2 std. dev. abundance, dolerite sills

0.5 Distance from Sill/Sill Thickness

Section MKR -A - Section CPZ Section MPI —B— Section MTR - * t~ Section TGA -+— Section MBO

Figure 32: Comparison of Si02 and KzO abundance vs. distance from intrusive bodies. There is a lack of correlation between the abundance of most elements and proximity to the intrusive body. The standard deviation for each element is plotted as a vertical bar two standard deviations in height, and standard deviations reported on the graphs are taken from five replicate analyses of sample MTM 269.0 (Appendix B). 135 MnO and N^O increase in abundance near the intrusive bodies, and approach the

mean chemical composition of the dolerite sills (Figure 33; Appendix B). This

implies that these elements experienced some post-depositional thermal alteration

that resulted from limited exchange between the sills and the country rock.

Chemical exchange with the sills was incomplete in the case of MgO, because

MgO concentrations in the sediment never reach the mean MgO content of 6.4%

that was measured in sills.

Organic carbon as a control on mudrock geochemistry

In this section, organic carbon contents and elemental abundances (not

normalized to a carbon-free basis) are compared to determine the extent to which

organic carbon controls elemental distribution in these mudrocks. If the abundance

of an element decreases as the organic carbon content increases, the result is

interpreted as a dilution effect caused by the influx of detrital carbon. If elemental

abundance increases as organic carbon increases, the result is interpreted as an

association of the element with organic carbon that may be due to sorption or chemical complexing with organic compounds. Abundances of representative major, trace and rare earth elements have been plotted against organic carbon content in a series of bivariate graphs, and representative results are shown in

Figures 34 and 35. Graphs produced during analysis of 15 representative major elements, transition metals, high field strength elements and rare earth elements are presented in Appendix B. A logarithmic scale is used for the axis so that Figure 33: Comparison of Fe2Os and MgO abundance vs. distance from intrusive intrusive from distance Fe2Os vs.of abundance MgO Comparison and 33: Figure

proximity to the sill and abundance of iron and magnesium. and iron abundanceof and sill the to proximity between correlation positive a show MPI and MTR Sections bodies. MgO (normalized %) Fe203 (normalized %) 14.0 12 10 0.0 4.0- 2.0- 3.0- 6.0- 5.0- 7.0 8 1.0- 0.0 2 4.0- 6 . . . . . 0 0 0 0 0 - - - - - 1

• 2 std. dev. std. 2 std. dev. std. - B - Section MTR MTR Section - B - Section MKR - A - Section CPZ Section MPI MPI Section CPZ Section - A - MKR Section Distance from Sill/Sill from Thickness Distance Distance from Sill/Sillfrom Thickness Distance — h - Section TOA —t— Section MBO —t— Section TOA Section dolerite sills dolerite abundance, abundance, Mean Fe203 Fe203 Mean dolerite sills dolerite abundance, Mean MgO MgO Mean 136 137 90- b 1 00 0

70- -fa* % 0 iP-iB ftcte xX_ J7 0 13 XE 60- +* f j y ^ +++ m + h + 0 D * >fel 0 & 50- X X 13 V ts H B 0 40- t/3 30 20- 1 0 - 1 2 std.dev.

0 - "i i—i tiiiii i—i i i i 1111------1—i—i i i rm------1---1—i i i i ri 0.01 0.10 1.00 10.00 100.00 Total Organic Carbon (%)

6.0 0 0 5.0H 0

. + + Ao"+ + . 0 ? 4 ^ X 13 ♦ *4-13 A xt- ++ 4> -F O 0 0 a 3-

* * 2 std. dev. X

0.0 -i 1 i i i i 111-----1--- 1—i i i i M i 1-- 1—rrrrrn----- 1--1—I III 0 J01 0.10 1.00 10.00 100.00 Total Organic Carbon (%)

A Pagoda + Mackellar n Fairchild x lower Buckley ® upper Buckley

Figure 34: Comparison of Si02 and K^O abundance vs. total organic carbon content. Most elements have a negative correlation with organic carbon content, suggesting that organic carbon acts as a dilutant. Vertical bars on each graph indicate the standard deviation of the element analyzed, and are taken from five replicate runs of sample MTM269.0 (Appendix B). 140t 138 0 120- 2 std. dev.

100-

B 80- a. + x*. -*■ +t- + + a 60- A + ++ +++ + + Z + A *K + + 40- + ^ + ▲ ▲ X 20- 0 0 H e 0 -I—I—I I II111--- 1 i—i i i r m ------1— i—i Mini------1— i—i i i 1111 0.01 0.10 1.00 10.00 100.00 Total Organic Carbon (%)

140 lower Buckley: upper Buckley: r = -0.31 r = 0.17 120- slope = -0.45 slope = 0.53 intercept = 67.49 intercept = 17.16

100-

x v x B 80H X E Cb a X g 60 X

IK 40-

2013 x 0 2 std. dev. 0 0 0 10 20 30 40 50 60 Total Organic Carbon (%) A Pagoda + Mackellar □ Fairchild x lower Buckley ® upper Buckley

Figure 35: Comparison of Ni abundance vs. total organic carbon content. The weak correlation between nickel content and organic carbon abundance suggests that organic carbon does not control nickel distribution. The top diagram shows this relationship for all four formations, whereas the bottom diagram concentrates on the Buckley Formation. 139 carbon-poor samples from the Pagoda and Mackellar Formations can be compared to carbon-rich samples from the Buckley Formation.

Two representative elements (Si02 and K20) are used to illustrate the most common relationship between elemental abundances and organic carbon contents

(Figure 34), and the remainder of these results are given in Appendix B. Results indicate that most elements decrease in abundance with increasing organic carbon content (Figure 34, Appendix B). A negative correlation is observed with the major elements (Si02, K20, A1203, NajO, MgO and Ti02), high field strength elements

(Hf and Th) and rare earth elements (La and Lu). This relationship is interpreted as a dilution effect, and discounts the hypothesis that complexing with organic carbon has been a major control on elemental distribution in Permian sediments from the

Beardmore Glacier region. Instead, the dilution effect is identified as a controlling factor on elemental abundance.

Other trends are evident on these diagrams, and include an increase in carbon content in the Buckley Formation compared to the underlying Permian units

(already discussed in Chapter ID) and a slight depletion in the abundance of many of the minor elements in the upper Buckley Formation. Data concerning lowered abundances of minor elements in the upper Buckley Formation will be discussed in later sections that analyze the provenance signal of Beacon sediments, but relationships between organic carbon and elemental abundances in the Buckley

Formation are explored further in this section. 140 Transition metal abundances have different chemical patterns in lower

Buckley vs. upper Buckley samples, and have been examined in greater detail using a second series of graphs (Figure 35, Appendix B). In these graphs, elemental abundances in the Buckley Formation are plotted on an arithmetic scale. Results of these detailed analyses indicate that Sc, V, Cr, Co, Ni, Cu and Zn have lower abundances in the upper Buckley Formation than in the lower Buckley Formation, but these changes are not strongly correlated with organic carbon content. A typical example of this relationship is shown in Figure 35, a plot of nickel abundance vs. organic carbon content. The very weak negative correlation between

Ni content and organic carbon content in lower Buckley samples is interpreted as the dilution effect discussed above. This general relationship between lower transition metal abundance in the lower Buckley Formation and an inverse correlation with organic carbon content holds true for the remainder of the transition metals analyzed (Appendix B).

Mineralogy and grain size as controls on mudrock geochemistry

The goal of this phase of the analysis is to examine the extent to which mineralogy and grain size act as major controls on the bulk geochemistry of these mudrocks. This is accomplished by identifying and analyzing the chemical components that make up the dominant sedimentary minerals. Silica, alumina and iron are the dominant chemical components of these mudrocks, since the known mineralogy consists largely of quartz (Si02), chlorite ((Mg,Fe+2,Fe+3,Al) 141 (Al,Si)4OI0(OH)2(Mg,Fe+2,Fe+\A l)3(OH)6) and iUite (KAl2(Si3Al)010(OH)2) (see

Chapter VI). Abundances of representative major elements, high field strength

elements, transition metals and rare earth elements are plotted against Si02, A120 3

and Fe203 abundances to indirectly examine elemental abundance patterns that are

controlled by the abundances of the minerals quartz, chlorite and illite. Patterns

that are related to provenance and paleoclimate are also evident on these graphs,

but analysis of these trends will be delayed until the following section, where

paleoclimate and provenance are discussed as controls on mudrock geochemistry.

The first mineralogic and grain size interpretations are conducted by plotting

element abundances vs. Si02 content. Relationships between SiOz and grain size

are strong in sedimentary rocks, since Si02 content is directly related to quartz

abundance, and grain size has a strong control on quartz distribution (Blatt and

Totten, 1981; Blatt, 1985). Three patterns are evident when normalized abundances

of representative major elements, transition metals, high Held strength elements and

rare earth elements are plotted against Si02 content. The most common pattern is a

decrease in elemental abundance with increasing Si02 content. Typical examples of

this relationship are shown by A1203 and Fe20 3 (Figure 36), and graphical results

from other representative elements are displayed in Appendix B. The elements Al,

Fe, Mg, Ti, K, Sc, Mn, Zn, Th and La all have a negative correlation with Si02. A

second pattern is demonstrated by the elements NajO and Hf (Figure 37), which exhibit a positive correlation between elemental abundance and Si02 content in the

Pagoda, Mackellar and Fairchild Formations. 142

2 std. dev. I

a 25

“ x

Si02 (normalized %)

14.0

^ 12.0H 2 std. dev. 1 $ ■g io.oH X E N ^% +f+

1 8- 0- E +tt ±!++ i-i o x x + -4 *. t jp B 6.0- * X"1 x □ — J. CO X A o 4.0- s X X X

Figure 36: Comparison of A1203 and Fe20 3 abundance vs. Si02 content. The negative correlation is interpreted as a mineralogic and grain size effect, with A12Oj and Fe203 carried by fine-grained clastic minerals. Figure 37: Comparison of NajO and Hf abundance vs. Si02 content. The positive The content. Si02 abundance vs. Hf and NajO of Comparison 37: Figure entf opsto rmteFlaFrain(art n tes 1986) others, and (Barrett Formation Falla the from composition tuff mean = F correlation is interpreted as a mineralogic and grain size effect, with NajO with effect, size grainand mineralogicinterpreted a is as correlation n fcridb ore lsi minerals. coarserclastic carried by Hf and Hf (normalized ppm) Na20 (normalized %) 0.0 0.5 2.0 2.5 3.0 3.5 1.0 1.5 22 20 10 12 14 16 18 J 2 4 6 8 0 5 0 5 0 5 0 5 90 85 80 75 70 65 60 55 50 0 5 0 5 0 5 0 5 90 85 80 75 70 65 60 55 50

Pgd + akla a Fairchild a Mackellar + Pagoda ▲ x lower Buckley Buckley lower x ▲ □ em - S i0 2 (norm alized alized (norm 2 i0 S S i0 2 (norm alized alized (norm 2 i0 S ,4+d*- 121 El h upper Buckley Buckley upper □ %) %) X 2 sd e. j std.dev. -6) E 143 144 The elements Ca, P and Lu show a third relationship to silica content, and are invariant or very weakly correlated with Si02 abundance (Appendix B).

These patterns are interpreted to result from grain size effects and associated changes in silicate and phyllosilicate mineral abundances. High Si02 abundance is interpreted to represent high quartz abundance, coarse grain size and relatively low clay mineral content. The negative correlation between Si02 and many metallic cations is due to a reduced abundance of clay minerals and the associated metallic elements in the coarser quartz-rich fraction. A positive correlation between Na and

Hf abundance and SiOz content is also interpreted as a grain size and mineralogic effect, with silica-bearing minerals serving as the carriers for these elements. Hf commonly occurs as a replacement for Zr in zircon, and the mineral Zr is concentrated in the heavy mineral fraction of sandstones. This association with coarser elastics may explain the positive correlation between Hf and Si02. Na may be carried either in detrital or authigenic albite grains or as a secondary zeolite accumulation. Zeolites are common in the associated sandstone beds (Vavra, 1984;

Vavra, 1989; Isbell, 1990), but this interpretation does not apply to mudrocks, since zeolites were not observed on x-ray diffraction patterns of mudrocks from the

Beardmore Glacier region (see Chapter V). The positive correlation between Na and SiOz abundance is tentatively interpreted as albitization of silica-bearing feldspar grains.

Elements that are poorly correlated with SiOz content either are not carried by the detrital clastic minerals, or are carried by minerals that occur in both the 145 coarse- and fine-grained fraction. CaO and P205 are probably carried by non­ silicate minerals, since they do not have a positive correlation with Si02 content.

These data suggest that the association between CaO and albite in these samples has a minor influence on the overall chemistry, and will be discussed further in

Chapter VI (mineralogy). The weak correlation shown by K20 and A1203 vs. silica content is interpreted as a result of co-occurrence of these elements in coarse­ grained silicate and fine-grained phyllosilicate minerals such as illite and potassium feldspar.

Grain size controls on mudrock geochemistry can also be examined using graphs of element abundance vs. F e ^ and A1203 concentration. Iron and aluminum are important constituents in the clay mineral chlorite, and aluminum also occurs in the clay mineral illite. Iron and aluminum are not found exclusively in clay minerals, but the abundances of these elements in bulk chemical analyses are interpreted to generally reflect the abundance of a fine-grained clay component, since other mineralogic carriers of Fe203 and A1203 were not identified. Graphs of element abundances vs. both A1203 and Fe203 concentrations are discussed together, since trends identified by these analyses are similar. Patterns shown on these two sets of graphs are the inverse of relationships observed earlier on graphs of element abundance vs. Si02 (Figure 36, Figure 37, Appendix B), which supports the interpretations described earlier about the relationships between grain size and Si02,

A1203 and FejOj abundances. 146 Patterns observed on graphs of A1203 and Fe203 content vs. representative element abundances are demonstrated by the representative elements Mg, Ti, K,

Mn, Sc, Zn, Th and La. An example of this relationship is shown in Figure 38, and complete results from plots of IS representative major elements, high field strength elements, transition metals and rare earth elements are contained in

Appendix B and Figure 39. Elements that are highly correlated to A1203 and Fe203 are metals that substitute for iron and aluminum. Transition metals substitute into the octahedral sites of phyllosilicate minerals and also occur as charge balancing cations in the interlayers of clay minerals (Newman, 1987). Increasing abundance of these elements is interpreted to represent increasing abundance of clay minerals, and therefore, decreasing grain size.

The very weak negative correlation between Si02, NajO and Hf contents and

A1203 and Fe203 abundances is also interpreted as a grain size effect, with Si02,

NajO and Hf carried by coarser grained clastic detritus, as discussed above

(Figure 39). Elemental abundances of CaO, P2Os and Lu are invariant or randomly variable over a range of A1203 and Fe203 abundances, and because this is consistent with earlier graphs vs. Si02 abundance, the interpretation of non-silicate mineralogic carriers is supported for CaO and P2Os. The element Lu has a low abundance in these sediments, and does not lend itself to interpretations involving grain size or mineralogy. iue 8 oprsno g bnac s A2 n F2 otn. The 3 A120abundance 3content. Fe20 MgO vs. and of Comparison 38: Figure entf opsto rmteFlaFrain(art n tes 1986) others, and (Barrett Formation Falla the from composition tuff mean = F positive correlation is interpreted as a mineralogic and grain size effect, size grain and interpreted mineralogiccorrelation is a as positive since these elements are common in the fine-grained clay fraction. clay fine-grained the in are common elements these since MgO (normalized %) MgO (normalized %) 12.0 10.0 14.0 10.0 12.0 14.0 0.0 2.0 4.0 6.0 8.0 0.0 2.0 4.0 6.0 8.0

2 6 1 1 14 12 10 8 6 4 2 0 1 1 2 2 3 35 30 25 20 15 10 5 Pgd + akla □ Fairchild □ Mackellar + Pagoda ▲ x lower Buckley & upper Buckley Buckley upper & Buckley lower x 203 nr lzd%) % alized (norm 3 0 e2 F A1203 (norm alized alized (norm A1203 **c x ck * -* * F g * * 4 =** * %) >?< El 2 2 std. dev. std. sd e. > dev. std. 147 iue3: ComparisonNajO abundance The of A120vs. 3 3 Figureand39:Fe20 content. entf opsto rmteFlaFrain(art n tes 1986) others, and (BarrettFormation Fallathe fromcomposition tuff mean = F with Na with negative correlationnegativeinterpreted is effect, mineralogicaand grainsize as Na20 (normalized %) Na20 (normalized %) 0.5 0.0 2.0 2.5 3.0 0.0 0.5 3.5 1.0 1.5 2.0 2.5 3.0 3.5 1.0 1.5

2 6 1 1 14 12 10 8 6 4 2 0 — a - 1 1 2 2 3 35 30 25 20 15 10 5 0 2 0 X X * +J + W* X 0 X * carried coarserby minerals.clastic * + x* X, A 0 0 X 0 X ^ ^ + ^ x F * F x Pgd + akla ° Fairchild ° Mackellar + Pagoda ▲ x lower Buckley s upper Buckley upper s Buckley lower x x + + + + x X e ■ F e203 (normalized %) (normalized e203 F x A1203 (normalized %) (normalized A1203 “ x x “ H .Hn a xa i+ > x > + +i+ > x XK-t V£x+ £ iV .x + + - i - > X 0 2 std. dev. std. 2 2 0 std. dev. std. 148 149 Provenance and paleoclimate as controls on mudrock geochemistry

Geochemical discussions and interpretations to this point have focused on thermal alteration, organic carbon contents, sedimentology, mineralogy and grain size as controls on mudrock geochemistry. The ultimate goal of this project is to identify a provenance and paleoclimatic signal in Permian sediments from the

Beardmore Glacier region, and this can be achieved now that the effects of other controlling factors have been identified. Thermal alteration is not a controlling factor in mudrock geochemistry except for the limited case of iron, magnesium, manganese and sodium in highly altered sections. Organic carbon distribution and sedimentologic controls have not significantly altered the geochemistry between the four units studied, and mineralogic and grain size effects have been identified.

With this information, additional geochemical patterns can now be discussed with reference to changes in source area, sediment supply and paleoclimate.

Results of provenance and paleoclimatic analysis in the Beardmore Glacier region

Several simple graphical methods were used to obtain information about

Permian provenance and paleoclimate in the Beardmore Glacier region, and results of these analyses are presented in this section. Initial discussion focuses on large- scale trends in sediment chemistry that are displayed on previously presented graphs. When the geochemical controls discussed previously have been identified on these graphs, remaining patterns can be attributed to changes in sediment supply or paleoclimate. Elemental ratios that have been useful in other studies of 150 mudrocks are then tested as more specific indicators of provenance and paleoclimate in the Beardmore Glacier region, and results are discussed below.

Data from air-fall tuffs from the Falla Formation (Barrett and others, 1986) are provided for comparison to a known volcanic source.

Large-scale elemental distributions as a provenance tool

Graphs that were used previously to examine organic carbon, grain size and mineralogic control also provide broad-scale information about chemical evolution of the sediment. Trends identified in the previous series of diagrams include the following:

• A1203 and SiO, abundances calculated on a carbon-free basis are higher in

the lower and upper Buckley Formation than in the underlying units

(Figure 36, Figure 38, Appendix B). Airfall tuffs from the Falla

Formation may trend toward slightly higher A1203 and Si02

abundances than the underlying Pagoda, Mackellar and Fairchild

Formations, but this difference is insignificant.

• Fe203 (and to some extent MgO and Mn) abundances calculated on a

carbon-free basis are lower in the lower and upper Buckley

Formation than in the underlying units (Figure 36, Figure 38,

Appendix B). The chemical composition of airfall tuffs from the

Falla Formation (Barrett and others, 1986) fall within the fields

defined by Buckley samples, and are consistent with the 151 interpretation that a volcanic influx is responsible for these chemical

differences in the Buckley Formation.

• Transition metal abundances calculated on a carbon-free basis are lower in

the lower and upper Buckley Formation than in the underlying units

(Figure 36, Figure 38, Appendix B). As discussed above, the

chemical composition of airfall tuffs from the Falla Formation

(Barrett and others, 1986) is consistent with the interpretation that a

volcanic influx is responsible for the observed chemical differences

in the Buckley Formation.

The mechanism for this geochemical change is interpreted to be an influx of silicic detritus, possibly associated with the volcanic input during Buckley deposition that was described by Barrett and others (1986) and Isbell (1990). These chemical differences are evident in both the lower and the upper Buckley Formation informal subunits, and may indicate early ashfall before the arrival of the main detrital pulse of volcaniclastic grains. Although the interpretation of an early ashfall component is not inconsistent with the available data, other possible interpretations can be advanced to explain the observed changes in chemistry.

It is also possible that a new silica-rich and trace metal-poor cratonic source area was unroofed or captured by the Buckley drainage system. The Beardmore and Byrd Groups contain quartzite beds, thick limestone intervals, and granitic intrusions that are also consistent with a chemical signal that is high in silica or depleted in trace metals. The paleocurrent reversal described by Isbell (1990) may 152 have provided a different type of source material from the new, southeasterly direction, but this event did not occur until midway through deposition of the

Buckley Formation. In contrast, the increase in carbon-free silica content and decrease in A1203, Fe203 and trace metal abundance described by these data occur at the base of the Buckley Formation, and are not inconsistent with an earlier input of siliceous material than the petrographic change observed by Isbell (1990).

Geochemical data from the Falla Formation (Barrett and others, 1986) are also not inconsistent with the interpretation of an ashfall influx in the Buckley Formation, since the Falla tuffs have a low Fe203 MgO and MnO content that is very similar to the composition of the lower and upper Buckley sediments.

Observations obtained from simple graphical analysis of the data are useful for large-scale generalizations, but do not show geographic variations in chemical abundances. A second series of diagrams is analyzed in the following section, to provide additional information about changing source areas and paleoclimate in the

Beardmore Glacier region. These new relationships are examined using multi­ element ratios, and large-scale geographic comparisons across the study area.

Geochemical ratios as provenance and paleoclimatic tools

Initial observations about large-scale elemental abundance patterns are now supplemented with geochemical ratios that provide specific information about geographic and stratigraphic patterns in sediment chemistry. Methods that have yielded information about provenance (and to some extent paleoclimate) in other 153 study areas are applied, and results are discussed for Permian mudrocks from the

Beardmore Glacier region. Nesbitt and Young’s (1982) Chemical Index of

Alteration (C.I.A.) provides information about paleoclimate and weathering conditions, while Al20j/Ti02 ratios, SiCyAl2C >3 ratios, K-jO/NajO and

KjO/CaO+NajO ratios each provide information about the source area. Background information that describes the theory behind each of these approaches is listed above (Chapter IV) in the section titled "Paleoclimate and Provenance as controls on mudrock geochemistry". Together this information begins to reveal the geochemical history of sediment supply to the Beardmore Glacier area.

An initial stratigraphic comparison of major element ratios was accomplished using Nesbitt and Young’s (1982) Chemical Index of Alteration

(C.I.A.). Large-scale geographic comparisons were also accomplished by dividing the study area into seven geographic regions and averaging the C.I.A. values within each region. Results of this analysis (Figure 40) reveal a strong upsection increase in the C.I.A. in the southern part of the study area, and weak upsection increases in the southwestern, northeastern, and (possibly) central regions. These stratigraphic trends can be interpreted to record changing patterns of weathering and paleoclimate in the Beardmore Glacier area. Trends in C.I.A. values are not consistent between most regions, although variation in the southern region is different and significant.

C.I.A. patterns are interpreted to provide an indication of weathering intensity and paleoclimate during deposition of the Permian sequence. Similar Average molar Al203/(A1203+Ca0 +Na20 +K20 ) ratios

(Nesbitt and Young’s C.I.A.)

North Northwest Northeast Central Southwest Southeast South upper Buckley lower Buckley / Fairchild upper Mackellar middle Mackellar

lower Mackellar

upper Pagoda

lower Pagoda I I 1 I | I I ■— T '1 I I T i—i—i- 60 65 70 75 80 60 65 70 75 80 60 65 70 75 60 65 70 75 80 60 65 70 75 80

Figure 40: Nesbitt and Young’s Chemical Index of Alteration increases in the southern part of the study area. This is interpreted as a weathering/climatic effect that developed on low relief floodplains

■p. 155 applications in the Karoo Basin of South Africa have revealed widespread increases in weathering intensity that correspond to the retreat of the Carboniferous/Permian ice sheet (Visser and Young, 1990). In the Beardmore Glacier area, the southern, central and northeastern regions have a distinct upsection increase in C.I.A. that is interpreted as an increase in weathering intensity associated with deglaciation of the

Beardmore Glacier region.

C.I.A. results in the remainder of the study area cannot be explained solely by a history of change that is completely analogous to that of Visser and Young’s

(1990) climatically induced upsection increase in weathering intensity, since C.I.A. values do not vary systematically within or between all regions. Many of the small-scale fluctuations in C.I.A. content are probably due to slight differences in grain size, and are not significant for paleoclimatic interpretations. An additional influence is proposed for the Beardmore Glacier region, where C.I.A. values appear to be filtered by other factors. C.I.A. values that do not increase systematically upsection are interpreted to have been influenced by paleoslope (relief) in the

Permian depositional basin. Paleoslope and residence time affect weathering intensity, so the changes in C.I.A. are not entirely due to climatic influence.

Isbell (1990) calculated paleoslopes for the Beardmore Glacier region, and found higher paleoslopes along the northern and western margins of the study area, with lower paleoslopes in the southern part of the study area. Isbell’s regions of high paleoslope correspond to areas in this study that have relatively invariant

C.I.A. values, while Isbell’s areas of lower paleoslope have C.I.A. values that 156 increase upsection in the expected manner. These results suggest that paleoslope has an effect on C.I.A. values. High paleoslope (high relief) is associated with rapid erosion, low residence times and an interpreted lack of chemical weathering.

Low paleoslope (low relief) is associated with reworking of existing floodplain sediments, higher sediment residence times, and a higher intensity of chemical weathering that affects the tectosilicate minerals and produces C.I.A. ratios that are more directly related to paleoclimate (Krissek and Homer, 1992).

Analysis of Al20/T i0 2 ratios is another method of observing provenance changes in the Beardmore Glacier region. Average Al20j/Ti02 ratios are shown in

Figure 41. Analysis of these results focuses on lateral (geographic) and vertical

(stratigraphic) variations in Al20/T i0 2 content and the geologic implications of these patterns. Geographic changes are examined by dividing the study area into seven regions to determine whether there are significant lateral variations in the supply of A1 and Ti. Results indicate that the Pagoda, Mackellar and Fairchild formations in the southern and possibly southeastern geographic areas have consistently lower Al20/T i0 2 ratios than the same formations in other regions.

This geographic variation is caused by higher than average TiOz contents in the southern and possibly southeastern sections. This suggests that the southern and southeastern geographic areas received titanium-enriched sediment from a different source than the remainder of the study area.

Paleocurrents (Isbell, 1990) indicate that the southern and southeastern parts of the study area received detrital sediment from the direction of the Geologists Average Al203/Ti02 ratios

North Northwest Northeast Central Southwest Southeast South upper Buckley lower Buckley / Fairchild / upper Mackellar middle Mackellar lower Mackellar

upper Pagoda lower Pagoda

15 20 25 30 15 20 25 30 15 20 25 30 15 20 25 30 15 20 25 30 15 20 25 30 15 20 25 30

Figure 41: Geographic and stratigraphic variations in Al20/n 0 2 ratios. Lower Al20/n o 2 ratios in the southern sections and higher Al20/T i0 2 ratios in the Buckley Formation are interpreted to represent changes in sediment supply. n ) 158 Range and the Miller Range (Gunner, 1983). These regions contain the oldest known basement material in the Beardmore Glacier area, and presumably have a different chemical composition than younger, more differentiated sediments of the

Beardmore and Byrd Groups. If Precambrian metavolcanics and argillaceous metasediments with composition similar to the Nimrod Group were exposed and contributed sediment during Permian time, these older metavolcanics and metasediments may be responsible for the high Ti02 signature observed in the southern part of the study area. This interpretation is consistent with known patterns of crustal evolution, since older Proterozoic crustal material tends to have chemical affinities with the deeper crust or mantle, while younger cratonic sediments have an evolved, sialic composition (Condie, 1982). Rock types that are consistent with a high Ti02 content include the general suite of mafic igneous rocks

(Cox, 1979; Condie, 1982).

In contrast, the remainder of the study area was supplied by southerly or southeasterly paleocurrents (Isbell, 1990) that provided detrital sediment from areas of the Queen Elizabeth Range and the Holland Range. Basement rocks presently exposed in these potential source areas include the Precambrian Beardmore Group,

Upper Precambrian to Cambrian Byrd Group and Ordovician Granite Harbour

Intrusives (Gunner, 1983). If units with composition similar to the Beardmore

Group, Byrd Group and Granite Harbour Intrusives were exposed during Permian time, these Ethologies may be responsible for the observed chemical patterns in

Permian mudrocks from the remainder of the study area. Granites, metamorphosed 159 carbonates and quartzites have a low Ti02 content (Cox and others, 1979; Pettijohn,

1975) that is consistent with the observed chemical composition in Permian mudrocks for the majority of the Beardmore Glacier region.

Stratigraphic variations in Al2Oj/Ti02 ratios are examined (Figure 41) by comparing A1203 to Ti02 ratios between the eight informal stratigraphic units in each of the seven regions. Although grain size variations contribute to the variability of these curves, results from the central, southwestern and southern parts of the study area indicate a general increase in A1203 to Ti02 ratios during Buckley deposition. Incomplete data do not permit analysis of the complete Fairchild -lower

Buckley- upper Buckley transition at every locality, but it appears that there was an evolution in the Al20/T i0 2 ratios that began with the lower Buckley Formation.

These stratigraphic increases in A1203 to Ti02 ratios may have been related to an influx of silica-rich (titanium-poor) calc-alkaline volcanics. These highly evolved, andesitic to rhyolitic volcanics have the lowest Ti02 content of any of the common igneous rock suites (Cox and others, 1979), and are consistent with the observed geochemical pattern.

Alternatively, the paleocurrent reversal discussed by Isbell (1990) may be responsible for exposing a new siliceous basement source such as the Precambrian to Cambrian Byrd Group (with abundant quartzitic sands) or Ordovician Granite

Harbor Intrusives. This paleocurrent reversal did not occur until midway through deposition of the Buckley Formation, so the change in sediment chemistry does not appear to coincide with the paleocurrent reversal. The timing of the siliceous influx 160 (carbon-free silica contents increase at the base of the Buckley Formation) favors the first hypothesis, with early siliceous ash fall in the lower Buckley Formation providing a silica-rich source of sedimentary debris.

Si02 to A120, ratios can also be used to examine stratigraphic and geographic patterns in sediment supply (Figure 42). Stratigraphic patterns generated by these data do not show consistent trends in the lower units, but indicate a relative increase in Si02 in the two areas that include samples from the upper Buckley Formation. Geographic variations in Si02 to A1203 content are not significant, since all of the geographic areas have similar Si(yAl203 ratios in the lower part of the section.

Much of the small-scale variation in SiOj/A^Oj ratios is probably due to differences in grain size between individual samples. The effects of grain size and mineralogy on sediment chemistry are well documented (Blatt and Totten, 1981;

Ingersoll and others, 1984; Roser and Korsch, 1986), and were identified previously as a potential control in the Beardmore Glacier region. Although every effort was made to sample only the finest-grained intervals, this is an imperfect method of controlling grain size, and samples range from fine-grained shale to shaley siltstone.

Much of the small-scale variation in the Pagoda, Mackellar and Fairchild

Formations is probably caused by these differences in grain size.

Large scale variations in Si(VAl203 ratios that occur simultaneously in different geographic areas are interpreted to record a change in provenance. The large relative increase in Si02 in the upper Buckley Formation is probably not Average Si02/Al20 3 ratios

North Northwest Northeast Central Southwest Southeast South upper Buckley lower Buckley / Fairchild \ upper Mackellar middle Mackellar lower Mackellar upper Pagoda lower Pagoda

123456 123456 123456 123456 123456 123456 123456

Figure 42: Geographic and stratigraphic variations in SiOj/A^Oj ratios reveal an increase in Si0j/Al203 content in the Buckley Formation and are interpreted to represent changes in sediment supply. ON 162 related to an increase in grain size, because most of these samples were collected from very fine-grained coal and shaley coal. Coal samples collected in this study were very fine-grained, and provide a very consistent method for controlling grain size. The two hypotheses for generating the high SiO/AljOj ratios in the upper

Buckley Formation are, again, an influx of volcanics, and a paleoslope reversal associated with increased uplift during deposition of the upper Buckley Formation.

In the first hypothesis, a majority of the detrital grains in the upper member of the

Buckley Formation are volcanic rock fragments (Isbell, 1990), and may be richer in silica than the mixed sedimentary, metasedimentary and volcaniclastic basement material that supplied detrital particles to the Pagoda, Mackellar and Fairchild

Formations. Increases in the SiOj/A^Oj ratio in the Buckley Formation are interpreted as the chemical signature of this influx of silica-rich calc-alkaline volcanic particles. In the second hypothesis, a paleoslope reversal described by

Isbell (1990) is responsible for the increase in SiO/AljO, ratios. As described above, paleocurrents reversed direction at the contact between the lower and upper members of the Buckley Formation (Isbell, 1990). The combination of a newly exposed (but presently unidentified) western source for siliceous basement material and increased uplift associated with development of the foreland basin complex may have combined to increase SiO/AljO, ratios in the (upper) Buckley Formation.

Data from SiCyA^O, ratios do not have the resolution to address these two hypotheses, especially because silicic cratonic areas of the areal extent required to affect this chemical change are unknown. 163 Plots of K20/Na20 and KjO/CaO+NajO ratios can be examined to show geographic and stratigraphic changes in the composition of fine-grained sediments

(Figure 43, Figure 44). Results from these plots are discussed together, since the ratios are designed to evaluate similar compositional trends. A significant stratigraphic trend in these data is the upward increase in KzO content relative to

CaO or CaO+NajO. This trend is most obvious in the central and southern sections, although the same relative increase in K20 is also present in the northeast

Relative potassium contents double or triple from the base to the top of these sections, and in the case of the Buckley Formation, may increase by an order of magnitude (Figure 43). Although it is clear that the Buckley Formation has a higher relative K20 content than the underlying units it is not obvious whether the increase is consistent from the lower Buckley member to the upper Buckley member, since the graphs (Figure 43, Figure 44) have opposite trends through this interval.

Stratigraphic trends in K20/Na20 and F^O/CaO+Na^ ratios are interpreted here in terms of increasing weathering or changes in the source material. Some of the relative upsection increase in K20 content may be the result of increased chemical weathering and differential ion mobility that occurred during erosion, transportation and re-deposition of the sedimentary particles. C.I.A. values

(discussed previously) indicate that there is a progression in weathering intensity from the mechanically weathered and glacially derived sediments of the Pagoda

Formation to the chemically weathered fluvial sediments of the Buckley Formation. Average K20/Na20 ratios

North Northwest Northeast Central Southwest Southeast South upper Buckley lower Buckley Fairchild upper Mackellar middle Mackellar lower Mackellar upper Pagoda lower Pagoda

i i ii i i r a — rTTTTTn i i m uni— i 11 mm i t mmi i mm i i H im — i 11 inn I JIMNB I I IIIIH i r i iiiti— i i liim I l l l i n I I HIM 0 10 100 0 10 100 0 10 100 0 10 100 0 10 100 0 10 100 0 10 100

Figure 43: Geographic and stratigraphic variations in KjO/NajO ratios revealan upsection increase in K^O/Na^ content and a low initial K20/Na20 ratio in the southern part of the study area. These differences are interpreted to result from changes in sediment supply. M 8 Average K20/Ca0+Na20 ratios

North Northwest Northeast Central Southwest Southeast South upper Buckley lower Buckley / Fairchild upper Mackellar middle Mackellar lower Mackellar upper Pagoda lower Pagoda

1 2 3 4 5 12345 12345 12345 12345

Figure 44: Geographic and stratigraphic variations in K20/CaO + Na20 ratios reveal an upsection increase in K20/CaO + Na20 content and a low initial K20/CaO + Na20 ratio in the southern part of the study area. These differences are interpreted to result from changes in sediment supply. 166 Less stable plagioclase feldspars that contribute sodium and calcium to the system are preferentially removed as the weathering intensity increases (Goldrich, 1938;

James and others, 1981), leaving more stable potassium feldspar or potassium-rich illite particles as the residual weathering product in the upper part of the section.

This hypothesis of differential ion mobility due to increased weathering and transportation is supported by the C.I.A. values discussed earlier, which indicate a slight upsection increase in weathering intensity.

Other known changes that must be examined as potential causes of the upward increase in relative K20 content include differences in sediment supply associated with the paleocurrent reversal in the upper Buckley Formation, and a volcanic influx that occurred during deposition of the Buckley Formation. These changes in sediment supply are not likely explanations of the geochemical data, since K20/Na20 and K20/Ca0+Na20 ratios show a general increase through the four studied formations. The paleocurrent reversal and volcaniclastic influx discussed above are only effective as mechanisms of geochemical change during deposition of the Buckley Formation.

Geographic trends in K20/Na20 and K20/Ca0+Na20 ratios are evident when the southern and possibly southeastern regions are compared to the rest of the study area. Relative potassium contents are lower in these regions than in other geographic areas (Figure 43; Figure 44), and the differences in these sections are again interpreted as a difference in provenance. As discussed above (see section on

Al20/T i0 2 ratios), the Precambrian Nimrod Group is a likely source for the 167 sediment in the southern part of the study area, and the composition of the Nimrod

Group is different than the composition of the Beardmore Group, Byrd Group and

Granite Harbour intrusives that supplied detrital sediment to the remainder of the study area. The Precambrian tectonic is poorly understood, but speculation based on these data suggests that metasediments and metavolcanics from the Nimrod Group are relatively undifferentiated and have relatively low potassium contents when compared to the siliceous potassium-rich basement material that supplied sediment to the remainder of the study area.

Results of multivariate statistical analysis

Multivariate statistics can be used to identify complex relationships between groups of elements. Relationships that have been described previously for one or two elements at a time are now identified within the entire data set, and a comprehensive picture of chemical relationships becomes evident. Four relationships are established through multivariate statistical analyses of these geochemical data. The first relationship is obtained through cluster analysis, and describes groupings of generally similar samples within the data set. The remaining three relationships discussed in this study were identified by principal component analysis. An initial round of principal component analysis identifies the variables

(major elements) that are responsible for the similarity groupings described by cluster analysis. A second round of principal component analysis identifies specific variables responsible for compositional similarity after the effect of a major dilutant 168 (organic carbon) is removed, and the third approach compares elemental

associations in altered and unaltered samples to evaluate elemental mobility during

diagenesis.

Chemical analyses presented in Appendix B were used as the initial data set for multivariate statistical analyses. Additional results of organic carbon analyses are available in Chapter m . Cluster analysis of the major element data identifies five clusters, with four of the clusters related to two stratigraphically separate packages of rock (Figure 45). Clusters two and three contain 67% of the samples from the Buckley Formation, and are composed of 83% and 100% Buckley samples, respectively. Clusters four and five contain 76% of the samples from the

Mackellar Formation, and are composed of 50% and 85% Mackellar samples, respectively. These results identify the Buckley Formation and the Mackellar

Formation as chemically distinct, but do not isolate the elements that are responsible for the groupings. This clustering by formation does, however, indicate a stratigraphic pattern to the major element chemistry, and warrants further investigation by other statistical methods.

Principal component analysis identifies groups of variables (elements) that covary within the data set. In this study, several complex relationships between elements were revealed by manipulating and reanalyzing the data three times.

Principal component analysis was first performed on the bulk major element and organic carbon abundance data (Figure 46). The first principal component identifies two chemical end-members that vary inversely. Organic carbon is one 169

c Cluster Analysis: Major Elements o n=23 n=12 n—8 n—12 n—26 fic/5 WjE 100%

U x: m m n 2 a 50% O <4-* * * *"* f t t ; ® O "O O h «S«

£ O h 2 3 4 5 os u Cluster

Wtifa Pagoda H Mackellar Fairchild llllllllll Buckley

Figure 45: Results of cluster analysis using major element concentrations from Carboniferous/Permian mudrocks. Clusters two and three are dominated by samples from the Buckley Formation, while clusters five (and to a lesser extent cluster four) show a chemical distinction in the Mackellar Formation. Figure 46: Graphical representation of results obtained from principal component component principal from obtainedresults of representationGraphical 46: Figure Loading on principal component - 0.fr -0 0 . 2 interpreted to represent detrital siliciclastic dominance in the lower units. lower the in dominancesiliciclastic detrital represent to interpreted is which association element major a Formation,and Buckley the in influx (shown) describes an organic carbon component which dilutes the clastic clastic the dilutes which component organiccarbon an describes (shown) one component Principal carbon.organic and elements major of analysis - MgO Fc203 A1203 K20 P205 Si02 Na20 CaO Corgar Corgar CaO Na20 Si02 P205 K20 A1203 Fc203 MgO .2 0.41 0.42 Major elementsand organic carbon Major element (oxide) element Major .0 .9 a26 0.29 0.30 170 171 end-member, with a highly negative loading, and the remainder of the major elements have highly positive loadings and comprise the other end-member. Scores for the individual samples show that this relationship is especially important in the

Buckley Formation, where 30 out of 36 (86%) of the Buckley samples have negative scores. This pattern indicates that organic carbon abundances are higher in the Buckley Formation, whereas major element abundances are higher in the underlying units. Field observations and organic carbon measurements further verify the upsection increase in organic carbon, since the uppermost unit studied

(Buckley Formation) contains carbon-rich coaly interbeds, while the lower units do not contain coal (see Chapter III for complete discussion of organic carbon content).

Principal component two, defined during the analysis of major elements and organic carbon, describes 19% of the variance in the data set, and contains a mixture of weakly significant and uninterpretable results. Principal component two has highly positive loadings on CaO, P2Os, MgO, Fe20, and organic carbon, and highly negative loadings on Si02 and K20. Scores for principal component two indicate that elements with negative loadings are most important in the Buckley

Formation, with 64% of the Buckley Formation included in the group of samples that has negative scores. The relationships described by CaO and P2Os are not interpretable in a geologic or mineralogic context, and for these elements the analysis is probably responding to high variability and very low elemental abundances. 172 Geologically significant interpretations are associated with the remaining

loadings, and are interpreted as a contrast between a tectosilicate abundance

(negative loadings on Si02 and K20 indicate a quartz or feldspar abundance) and a

phyllosilicate/organic carbon abundance (positive loadings on MgO, FezO, and

organic carbon indicate a chlorite and organic carbon abundance). Scores indicate

that the tectosilicate association is important in the Buckley Formation, and this

confirms some of the earlier bivariate plots that describe an increasing importance

of quartz in the Buckley Formation. Phyllosilicates were previously identified as

important in the lower units, and this is also confirmed by principal component

two. The association with organic carbon that appears to be present in the lower

units was not previously described, may be related to variations in organic carbon

content that are related to subtle changes in grain size. Principal component two

contains some geologically meaningful results, but also describes minor and

insignificant associations in the data set.

Principal component three describes 13% of the variance in the data set.

NajO, organic carbon, CaO and Si02 have highly positive loadings, while K20 and

Fe2Os have highly negative loadings. Scores on individual samples do not indicate

any significant stratigraphic associations, and loadings are not easily interpreted in a geologic context. For future principal component analyses, the discussion will be limited to principal component one, which describes the majority of the variability in the data set. 173 The relative importance of organic carbon is useful for differentiating

Buckley Formation samples from those collected in underlying units, but dilution by organic carbon may obscure smaller variations in the abundances of inorganic elements that can be used to interpret changes in detrital mineralogy. The next step, therefore, was to remove the dilution effect by normalizing the major element abundances to account for variations in organic carbon content. The data were normalized by setting the sum of the major elements equal to 100%, and recalculating the percentage contribution of each inorganic major element to that total. Corrected (carbon-free) major element values were then examined using principal component analysis, and those results are discussed below.

The first principal component determined by analysis of the carbon-free major element abundances explains 37% of the total variance in the new data set, and identifies two new end members that vary inversely (Figure 47). One end member is represented by positive loadings on Mg, Fe, A1 and P, and the other end member has a negative loading on Si. Elements with smaller loadings (Ca, Na and

K) do not covary strongly with either endmember, and are not considered further here. Scores for individual samples show that principal component one has a consistent stratigraphic distribution, with negative scores for 23 of 36 samples from the Buckley Formation and positive scores for the majority of the samples in the lower units. This indicates that Si is relatively more abundant in the Buckley

Formation, and Mg, Fe, A1 and P are relatively more abundant lower in the section. Figure 47: Graphical representation of results obtained from principal component component principal from obtained results of representation Graphical 47: Figure Loading on principal component carbon contents. Principal component one (shown) describes a tectosilicate tectosilicate a describes (shown) one component Principal contents. high carbon for account to normalized concentrations, elements major of analysis (represented by MgO, Fe20 3, and Al203) in the lower units. lower the in Fe20 3,Al203) and MgO, by (represented (Si02) dominance in the Buckley Formation, and a phyllosilicate abundance abundance phyllosilicate a and Formation, Buckley the in dominance (Si02) MgO Fe203 A1203 P205 CaO Na20 Si02 Si02 Na20 CaO P205 A1203 Fe203 MgO Majornormalized elements,carbon-free Major element (oxide) element Major K20 174 175 Patterns identified in the carbon-free geochemical data can be used to interpret changes in detrital mineralogy and provenance within the four formations studied. These samples have also been analyzed using X-ray diffraction, and general trends in mineralogy (see Chapter V) support these interpretations of the geochemistry. The Mg/Fe/Al/P end-member is interpreted to represent a phyllosilicate component, since Mg/Fe/Al are the building blocks for many clay minerals. This relationship was previously identified using bivariate plots of Fe and

A1 abundances, and is now confirmed using multivariate statistics. This interpretation is also supported by mineralogic analysis using X-ray diffraction, which confirms that chlorite and illite are found in most samples, and have a higher relative abundance in the lower units (see Chapter V; also see Krissek and Homer,

1991). The Si-rich end-member defined by principal component one is interpreted as representing a tectosilicate component, since Si is an important elemental constituent of tectosilicate minerals. These interpretations are again supported by mineralogic analysis using X-ray diffraction (see Chapter V; also see Krissek and

Homer, 1991), which confirms that quartz and feldspar are abundant in these sediments. Although phosphorus is included with the major elements, the abundance of phosphorus is low and phosphorus-bearing minerals are not a major mineralogic constituent of the mudrocks. Phosphorus-bearing minerals were not identified in an x-ray diffraction data (see chapter V). As a result, the significance of phosphorus within this principal component is unknown at this time. 176 Using these interpretations, the scores calculated for each sample can now be examined as a stratigraphic record of mineralogic change. Chlorite and illite are interpreted as important detrital components in the Pagoda and Mackellar

Formations, and quartz and feldspar become more important as detrital constituents in the Buckley Formation. Grain size differences in the intervals sampled may have contributed somewhat to this pattern, but are an unlikely source for all the observed variation, since all samples are from relatively fine-grained intervals. As a result, these mineralogic changes are interpreted to be the result of changes in the original sediment supply. Possible causes for the observed chemical variation include a volcanic influx that acted as a new source for detrital sediment, and changes in paleocurrents associated with a newly developed compressive margin along the Permian margin of Antarctica (Collinson, 1990; Isbell, 1990).

Multivariate statistics do not identify a chemical difference between the lower and upper Buckley Formations, and instead indicate that the Buckley Formation as a whole was reacting to changes in sediment supply. This suggests that the paleocurrent reversal that occurred at the base of the upper Buckley Formation is not responsible for the observed variation. An influx of volcaniclastic sediment, possibly associated with an early ash-fall component, is favored as an interpretation of these results. It is important to emphasize that these conclusions are based on analysis of mudrock data, and that similar chemical analyses of the sandstones might support the petrographic change described by Isbell (1990) for sandstones of the upper Buckley Formation. Ill The final step in the statistical analysis was designed to examine the mobility of the major elements during burial diagenesis and the secondary thermal alteration caused by Jurassic intrusive events. An assessment of mobility is important, because interpretations of the geochemical data that invoke differences in terms of provenance changes assume that the original major element chemistry has remained essentially unchanged since Permian time. To test this hypothesis, vitrinite reflectance measurements and the distance of each sample from its nearest intrusive body were used to separate the samples into a group of relatively unaltered samples and a group of relatively altered samples (Homer and Krissek,

1991). Principal component analysis was run on each group of samples, and the results are compared in Table 10.

Results from principal component analysis of the unaltered samples are very similar to the results obtained from principal component analysis of the altered samples. In the relatively unaltered sample set, principal component one identifies two end-members, with large positive loadings on Al, Mg and Ca, and a large negative loading on Si. In the relatively altered sample set, principal component one identifies two end-members, with large positive loadings on Fe, Mg, P and Ca and a large negative loading on Si. A scatter plot of loadings from the two data sets demonstrates the correlation between results of the two analyses (Figure 48).

The regression line defined by the data has a slope close to one, with a high correlation coefficient (0.78). These statistics indicate that there is no significant difference in elemental associations and behavior between the unaltered samples 178 Table 10: Comparison of loadings from unaltered and altered sample sets. Samples are categorized as relatively unaltered or relatively altered on the basis of vitrinite reflectance data, in order to examine elemental mobility during thermal alteration.

LOADINGS ON PRINCIPAL COMPONENT ONE Unaltered Samples Only Altered Samples Only Major Elements Major Elements Element Normalized Carbon-Free Normalized Carbon-Free Si02 - 0.56 - 0.46 A1203 +0.48 +0.25 CaO +0.37 +0.31 Na20 - 0.22 +0.20 K20 - 0.24 - 0.11 P205 +0.23 +0.38 Fe203 +0.11 +0.46 MgO +0.38 +0.47 Figure 48: Graphic comparison of loadings on principal component one for data set data for oneprincipalcomponentloadings of comparisonon Graphic 48: Figure

Loadings with unaltered samples hmcldfeec ewe h lee n nlee ape. The samples.unalteredandbetweenaltered differencethe chemical little is there that confirms sets data twobetweenthe correlation close The intrusion of diabase sills and dikes.andsills diabase of intrusion possible exception is Fe20 3, which may have been mobilized by theFe20 3, bymobilized is beenexceptionpossible have which may only.samplesunaltered with set samplesdataalteredand includes which Unaltered samples vs. altered samples altered vs. samples Unaltered - -0.4 - - 0.0 0.8 0.2 0.4 0.6 0.2 0.6 0.8 08 06 04 02 00 . 04 . 0.8 0.6 0.4 0.2 -0.0 -0.2 -0.4 -0.6 -0.8

Comparison of sample sets: sample of Comparison r = = r actual slope = 0.72 = slope actual Loadings with altered samples altered with Loadings 0.83

179 180 and the altered samples. Similar conclusions were also obtained using bivariate plots of element abundance vs. proximity to an intrusive body, and are now confirmed using multivariate statistics. This conclusion is geologically important, since it implies that diagenesis and later thermal alteration have not significantly altered the bulk geochemical signal of these Permian mudrocks.

The high degree of correlation between the two data sets is even more remarkable when we consider the maximum extent of alteration recorded by these samples. Highly altered samples were collected close to intrusive bodies, and have vitrinite reflectance values that often exceed 4.0 R0 (reflectance in oil), with a maximum measured vitrinite reflectance of 6.23 R0 (Homer and Krissek, 1991).

For comparison, these values correspond to low temperature metamorphism, anthracite coal rank, and conodont alteration index values greater than four (Dow,

1977; Tissot and Welte, 1984). Although it is impossible to make exact estimates of paleotemperature, theoretical calculations for a similarly intruded sequence predict the temperature at the contact of the intrusive bodies to be in excess of 650°

C (Jaeger, 1957). The bulk geochemistry of these mudrocks has been relatively unaffected by these relatively severe conditions; factors which may have contributed to this behavior include low sediment permeability and limited volumes of fluid flow through the mudrocks. In addition, grain-scale effects of alteration have been homogenized by our analysis of bulk samples.

Of the elements considered here, iron appears to be most affected by secondary mobility. Iron has a lower loading on principal component one in the 181 unaltered sample set than in the altered sample set, and this indicates that variance in iron content increases when altered samples are analyzed. This would be expected if the abundance of iron in a particular sample is a result of both primary and secondary processes. The geologic interpretation for these observations lies in the iron-rich nature of the Jurassic sills and dikes. Diabase (dolerite) intrusions are iron rich (Elliot, 1972), and iron is one of the more mobile major elements. The differences between results of principal component analysis of unaltered samples and altered samples are therefore interpreted to record a small amount of iron mobility during the Jurassic intrusive event.

Summary and conclusions

Geochemical data are used to provide information about sediment supply to the Beardmore Glacier region during Permian time. The first step in these analyses is to identify the factors that control sediment geochemistry. A Jurassic thermal event caused both localized and regional alteration of the Permian sediments, so the first step of the analysis is to examine thermal alteration as a potential control on sediment chemistry. Sections with well-established alteration patterns are used to examine chemical variations near intrusive bodies, and results are compared for different groups of elements. The majority of the elements analyzed are not affected by proximity to an intrusive body or by changing intensity of thermal alteration (as represented by vitrinite reflectance measurements). The conclusion generated by these results is that most major elements, transition metals, high field 182 strength elements and rare-earth elements have not been mobilized by thermal alteration.

A small group of elements do show limited mobility and alteration in regions that experienced the most intense thermal alteration. F e ^ , MgO, MnO and NajO are mobilized in stratigraphic sections that have the highest vitrinite reflectance values and thickest intrusive bodies, but are relatively immobile in stratigraphic sections that are less altered.

Preferential complexing of metallic cations with organic matter was also examined as a potential control on sediment geochemistry. Results indicate that organic carbon content is not related to the abundance of most elements analyzed, except as a dilutant. The Buckley Formation, which has the highest organic carbon content and the highest potential for complexing of trace elements with carbon compounds, does not show a significant correlation between organic carbon content and transition metal abundance.

Grain size and mineralogic effects are also analyzed to determine the extent of their control on mudrock geochemistry. Grain size and mineralogic effects are found to exert a strong control on bulk chemical composition of the mudrocks, and associations of elements that group together in different mineral assemblages and grain size categories are identified. The abundances of most metallic cations are directly related to the abundances of A1203 and Fe203, and this is interpreted as a geochemical indicator of clay mineral abundance and fine grain size. NajO and Hf 183 concentrations are strongly correlated with Si02 abundance, and this is interpreted as a geochemical indicator of tectosilicate abundance and coarser grain size.

Once the effect of these controls on sediment chemistry has been identified, additional interpretations are made using elemental ratios that are designed to indicate changes in sediment source area or weathering conditions in sedimentary rocks. These elemental ratios support the following statements:

• Sediment supply changed during deposition of the Buckley Formation.

This is shown by a decrease in the abundance of iron and metallic

cations, an increase in organic carbon content and an increase in Si02

and A1203 abundance. Two hypotheses are available to explain this

chemical evolution. Changes in chemistry may be due to a siliceous

volcanic influx, or changes in sediment chemistry may be due to a

paleocurrent reversal and sediment input from a new source area.

The timing and geochemical signature of the event are not

inconsistent with the volcanic model, and geochemical similarities

between the Buckley Formation and averaged airfall tuff

compositions (Barrett and others, 1986) support the interpretation that

an early ash fall contributed sediment before the arrival of the

volcaniclastic wedge.

• The southern part of the study area received sediment from a different

source than the remainder of the study area. Geochemical analyses

reveal that Al20/T i0 2 ratios are low and FtjO/Na^ ratios are high in 184 the southern part of the study area. These are interpreted as

provenance signals from a less differentiated (older?) cratonic source

area, and may also indicate increased chemical weathering in the

southern part of the study area. This chemical weathering is minimal

in the lower part of the section, and increases upward. Precambrian

metasediments and metavolcanics similar to the Nimrod Group are

favored as a likely contributor of this detrital material, while silicic

metasediments similar to the Beardmore Group, Byrd Group and

Granite Harbour Intrusives are postulated to have supplied detrital

sediment to the remainder of the study area.

• Fairchild and Buckley sediments deposited in the southern part of the

study area also experienced more severe chemical weathering than

those deposited in the rest of the Beardmore Glacier region, and this

is interpreted as a climatic effect. Long residence times in broad,

flat floodplain environments may have enhanced chemical weathering

that was associated with the retreat of the Carboniferous/Permian ice

sheet.

Multivariate statistical analyses also provide insight into the geochemistry of the fine-grained intervals. Cluster analysis of major element abundances identifies the Buckley Formation and the Mackellar Formation as chemically distinct.

Principal component analysis using major element abundances and organic carbon contents indicates the presence of two compositional end members: a clastic component rich in inorganic major elements, and an organic component rich in

organic carbon. The organic end member dilutes the signal in the upper part of the section (Buckley Formation), as also indicated by field observations and the distribution of total organic carbon. When major element abundances are normalized to remove the effects of these variable organic carbon contents, a geochemical signal related to detrital mineralogy and provenance can be interpreted.

Principal component analysis of the carbon-free abundances is interpreted to indicate the presence of two clastic end member compositions: a phyllosilicate component rich in Fe, Mg and Al, and a tectosilicate component rich in Si. Clay minerals are important components of the Pagoda and Mackellar formations, while tectosilicate minerals (quartz and feldspar?) become more important in the Buckley

Formation.

Results of principal component analysis were also used to examine major element mobility during burial diagenesis and low-grade thermal alteration. Results of principal component analysis of a data set composed of unaltered samples correlate very closely to results from principal component analysis of all samples

(both altered and unaltered). This similarity indicates that the major elements have been relatively immobile since the Permian, so that these mudrocks have acted as essentially closed systems during thermal alteration induced by proximity to intrusive bodies. 186 Studies of elemental mobility raise the question of maximum temperatures of alteration in Beacon sediments. In this study, vitrinite reflectance values exceed

6.0 Ro in highly altered samples, and correlate with conodant alteration indices

(CAI) in excess of 5 (Figure 21). This indicates a temperature of alteration greater than 400° C (Harris, 1979).

Mineralogic assemblages concur with this minimum temperature estimate, since the illite and chlorite assemblage observed in Beacon mudrocks (see Chapter

V ) is stable at temperatures greater than 300° C (Hoffman and Hower, 1979). The zeolite mineral analcime was also identified in highly altered Beacon sandstones

(Barrett and others, 1987), and this mineral is stable at temperatures in excess of

400° C (Ghent, 1979). The conclusion gained from this combination of mineral stability data is that temperatures of alteration exceeded 300° - 400° C in close proximity to intrusive bodies.

The estimates of temperatures of alteration based on mineralogic stability may be lower than the actual temperatures of alteration, because the mineral assemblage may not have equilibrated during the intrusive events. Organic carbon compounds reacted rapidly to the alteration, and probably give a more accurate indication of the maximum temperature of alteration. Organic carbon compounds indicate temperatures in excess of 400° C, with maximum temperatures that may approach the 600° C predicted by Jaeger (1957; 1959). Mineralogic assemblages are consistent with greenschist facies metamorphism (Bostick, 1979), and suggest maximum temperatures greater than 400° C for Beacon mudrocks. CHAPTER V

MINERALOGY

Introduction

In this phase of the study, the mineralogy of Permian mudrocks from the

Beardmore Glacier region is analyzed, and mineralogic information is used to provide additional insight into provenance and paleoclimate during deposition of the

Pagoda, Mackellar, Fairchild and Buckley Formations. Although mudrocks contain a significant proportion of detrital quartz and feldspar, clay minerals are the most abundant mineral group in most fine-grained clastic deposits. Analysis of the mineralogy of mudrocks is, by necessity, a study of clay mineralogy. Potter and others (1980) compiled an average mineralogic composition of more than 300 shales of various ages, and found that these rocks contained an average of 38% clay minerals, 28% quartz, 6% feldspar, 5% carbonate and 2% iron oxide. The mineralogic composition of mudrocks from the Beardmore Glacier region is summarized below, and significant differences in the mineralogy are interpreted with respect to changes in provenance and paleoclimate.

The high clay content of mudrocks can be an asset in studies of provenance and paleoclimate. Quartz and feldspar usually have a detrital origin in mudrocks,

187 188 but the origin of clay minerals can be either detrital or authigenic. The advantage of studying clay minerals is that they respond very quickly (in a geologic sense) to variations in the physical environment, and often record changes that are not observable in the mineralogy of more stable silicates. Detrital clay minerals are deposited as clasts that were derived from older igneous, metamorphic or sedimentary rocks, and often provide information about the source area. Authigenic clay minerals can form during weathering prior to transport, and this alteration of the original mineralogy gives insight into weathering conditions and climate in the geologic past. Relative input from these potential sources of clay minerals is difficult to determine in many natural systems. In cases where the source of detrital vs. authigenic mineralogic variation can be isolated, the relative abundances of clay minerals provide useful information about subtle changes in paleoclimate and provenance.

Clay minerals are also sensitive indicators of secondary diagenetic and thermal alteration. In the Beardmore Glacier region, mineralogic composition of

Permian mudrocks provides additional evidence about the post-depositional history of the sediment. Clay minerals respond rapidly to changes in temperature and pressure, so clay minerals can be used to document differences in burial diagenesis or thermal alteration that are not recorded in the more stable silicate minerals. In this study, the crystallinity of illite and the presence of illite polytypes are examined as methods for determining the extent of alteration in mudrocks. Changes in the bulk composition of the sediment are also used as a qualitative measure of 189 alteration, based on the theoretical temperature stability fields of common clay

minerals.

Factors that control mineral distribution in mudrocks

Several factors control mineral abundances in mudrocks. The significance

of each factor varies according to the individual depositional system, and an

evaluation of past conditions in the Beardmore Glacier region helps to identify the

factors that control mineral abundance patterns in this area. Factors that have been

cited as potential controls on the mineralogy of mudrocks include source rock

composition, weathering conditions (climate) in the source area, authigenic

alteration of the mineral assemblage during transportation and deposition of detrital

sediment, and post-depositional diagenetic or thermal alteration. All these factors

have some interplay in sedimentary systems, but a careful analysis helps to identify

the factors that control the mineralogy in the Beardmore Glacier region.

Mudrock mineralogy and source area lithologv

Source area lithology has often been cited as a major control on the

mineralogy of clastic sedimentary systems. Numerous studies have shown that the mineralogy of clastic rocks is related to the mineralogy of the source region, and this relationship has recently been confirmed for mudrocks. A significant proportion of detrital grains in mudrocks may be composed of recycled material from older sedimentary source rocks (Krissek, 1989; Friis and others, 1979). Bucke 190 and Mankin (1971) analyzed the chemistry and mineralogy of an interbedded shale and sandstone sequence that is lithologically very similar to the Beardmore sediments. They used S.E.M. photos of grain morphology to conclude that well- crystallized illite and chlorite were predominantly detrital, and that "Quantitatively, authigenic mineral formation was not significant..." Work by Hayes (1973), Blatt and Totten (1981), Blatt (1985), Blatt and Caprara (1985) and Thomas and Murray

(1989) supports this conclusion, and emphasizes the fact that the mineralogy of detrital sediment relates directly to the mineralogy of the source area. These authors all studied fine-grained sediments, and were able to make provenance interpretations on the basis of the mineralogy of mudrocks.

In the Beardmore Glacier region, much of the distribution pattern observed for individual minerals can be explained by examining the mineralogy of the source area that supplied detrital sediment. Fluvial, lacustrine and glacial depositional environments have the highest potential for preserving a mineralogic signal from a discrete source area (Chamley, 1989), and these depositional environments are all represented in the units examined in this study. The one depositional environment that may not meet this generalization is that recorded by the Mackellar Formation, where detrital grains were subjected to extended transport in the water column. In the case of the Mackellar Formation, mineralogic patterns will be closely examined to evaluate the relative effects of source area mineralogy and transport processes within the depositional basin (see section below, entitled "Mineral composition and depositional processes"). In general, however, mineralogic patterns in the 191 Beardmore Glacier region are strongly influenced by the composition of the source area.

Mudrock mineralogy and paleoclimatic conditions

Climatic conditions are often cited as a factor that affects the mineralogy of detrital sediments (James and others, 1981; Singer, 1984; Dutta and Suttner, 1986;

Chamley, 1989; Krissek, 1989). Climatic conditions control the type and intensity of weathering that occurs in an area, and different climatic regimes produce characteristic weathering products. Two end-members in the spectrum of weathering processes are chemical weathering and physical weathering, and each can produce a different mineralogic signal. Chemical weathering hydrolyzes and oxidizes unstable minerals, yielding new mineralogic assemblages that reflect climatic conditions at the time of erosion and re-deposition of the sediment. At the other end of the spectrum, physical weathering produces detrital sediments that closely resemble the original mineralogy of the source area. These general relationships have been used by many authors to interpret paleoclimatic history from detrital sediment composition.

The connection between climatic conditions and sediment mineralogy was first expressed clearly in the world’s oceans, where a global perspective allows the observation of large-scale weathering patterns on land masses that bordered the ocean basins (Biscaye, 1965; Griffin and others, 1968; Lisitzin, 1972). These authors found four general geographic and climatic associations that correspond to 192 the chlorite, illite, smectite and kaolinite families of clay minerals. These climatic associations are gross oversimplifications of a very complex system that includes source area input and transport, but on a regional scale, the clay mineral abundances are very useful as indicators of weathering climatic conditions.

Chlorites are most abundant at high latitudes (Figure 49), where physical weathering is the dominant process and mineral abundance patterns reflect the mechanical erosion of basic source rocks (Chamley, 1989). Illites are common in mid-to-high latitudes (Figure 49), where temperate climates induce a combination of physical weathering and moderate chemical weathering in continental-type rocks.

Illites produced in this region reflect the dominant influence of mechanical erosion of the source area, but also indicate minor hydrolysis of unstable mineral components.

Kaolinites and smectites also have climatic associations, with kaolinites commonly found in equatorial regions (Figure 50) where high rainfall results in intense chemical weathering and extensive hydrolysis. High annual precipitation in these low-latitude settings leaches the cations from pre-existing silicate and phyllosilicate minerals, and favors the formation of kaolinite. Smectites do not follow a strict latitudinal zonation, but are most common in the mid-latitudes and temperate to subarid climatic zones (Chamley, 1989). Smectite is produced by a chemical weathering process, and in addition to climatic requirements, is favored by source areas that contain basic igneous rocks or volcanic deposits (Figure 50).

These general mineralogic and climatic associations are used as the starting point 193

Chlorite distribution:

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Illite distribution:

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0 2000km

E E i O 20-30 E i i i M J30’40 ^ H > s o

Figure 49: Chlorite and illite abundance patterns in the world oceans. Chlorite is a high latitude weathering product, derived from physical weathering of cratonic source material. Illite is a mid-latitude weathering product, derived from a combination of physical and chemical weathering. From Chamley (1989), after Lisitzin (1972). 194

Kaolinite distribution:

2000km

1 0 -2 0 □ ; 2 0 -3 0 > 6 0

Smectite distribution:

2000km

:-i30- 50

Figure 50: Kaolinite and smectite abundance patterns in the world oceans. Kaolinite is a low-latitude weathering product, formed by intense chemical weathering. Smectite is also a chemical weathering product, and tends to form in mid-latitudes near volcanic source areas. From Chamley (1989), after Lisitzin (1972). 195 for paleoclimatic interpretations using clay minerals. Although these generalizations are true in the world oceans and at continent-wide scales, it is important to realize that smaller-scale variations in drainage, topography, relief, source area and many other localized factors are also responsible for variations in clay mineral distribution.

The association between climatic conditions and clay mineral assemblages has also been examined in ancient sedimentary deposits, and this approach will be followed during analysis of Beardmore sediments. Studies of clay mineral distributions in modem and ancient sedimentary environments are summarized by

Weaver (1989) and Chamley (1989) and these studies are used as guidelines for this project. The ultimate goal is to use clay mineral distributions in ancient rocks as a record of climatic change in the geologic past.

Mudrock mineralogy and depositional processes

Depositional processes, including physical processes associated with grain transport, flocculation, differential settling and differential sorting have also been invoked as factors that control the mineralogic composition of detrital sediments.

These processes exert strong control on the mineralogy of detrital systems in environments where minerals are transported long distances prior to deposition.

Grain size, density, mechanical resistance and chemical stability are physical factors that affect the ability of a detrital grain to survive transport, and all the above- mentioned variables must be examined to determine their effects on mineralogic 196 patterns in Carboniferous(?) to Permian sediments from the Beardmore Glacier region.

Dispersal of detrital clasts in a basin generally results in deposition of larger or more dense grains in nearshore positions, and smaller, less dense grains in distal positions. This model applies to deposition of the basinal Mackellar Formation, where grains settle under the influence of gravity, but not to fluvial sediments of the Fairchild and Buckley Formations, where high sedimentation rates are responsible for some of the observed grain size patterns. Mechanical and chemical stability of the grains is also a factor in mineralogic distribution within a basin, with less resistant grains more abundant in proximal positions, and more resistant grains common in distal positions. These relationships were explored in mudrocks analyzed by Blatt and Totten (1981) and Blatt and Caprara (1985), who determined that quartz and feldspar abundances in mudrocks are inversely related to distance from the ancient shoreline. Transport and preservation potential of quartz and feldspar in a basin is a function of grain size, mechanical stability and chemical solubility of the grains, and differences in these physical properties result in a sedimentologic pattern that is controlled by the physical properties of the grains.

Differential flocculation is an additional depositional process that controls mineral distribution in some mudrocks. Gibbs (1985) experimented with settling velocities of clay particles, and found that settling velocity is related to the formation of floes. Floes commonly form when clay minerals are introduced from fresh to salt water, so this work has potential application in marginal marine 197 environments. Gibbs (1985) determined that there is a range of settling velocities for floes formed from the major groups of clay minerals, with velocity,mte > velocity*,,,^ > velocity,™^ for a given particle size. In natural systems, the density of the floes becomes a controlling factor, and denser kaolinite and illite floes settle in a nearshore or estuarine position, while less dense smectite floes are transported farther out to sea (De Segonzac, 1970; Chamley, 1989; Thomas and

Murray, 1989). This results in the deposition of bands of clay minerals as clay-rich fresh water enters a saline body of water.

Differential settling, mineral stability and flocculation effects are potential controls on the mineralogy of mudrocks, but the importance of these controls is probably minimal in the Beardmore Glacier region. Processes that sort or fractionate detrital sediment are more effective as transport distance increases, and these conditions did not exist in the Beardmore Glacier region, with the possible exception of deposition of the Mackellar Formation. Rapid subsidence during deposition of the fluvial facies of the Buckley Formation caused rapid burial of detrital grains. This removed the grains from the effects of near-surface transport and fractionation processes before the mineralogy was significantly affected. The glacial environment that was present during deposition of the Pagoda Formation was also ineffective at inducing selective transport or fractionation of detrital grains.

The Mackellar Formation was deposited in a large basin where processes that sort or fractionate sediments were potentially more effective, so mineralogic patterns in 198 the Mackellar Formation will be examined closely to determine whether transport processes have exerted a controlling influence on the mineralogy.

Mudrock mineralogy and post-denositional alteration

Post-depositional alteration in mudrocks can be a result of burial diagenesis, or it can be caused by igneous and tectonic activity that raises temperatures above the normal thermal regime. Most studies of mudrock alteration have concentrated on the effects of burial diagenesis and the mineralogic changes that take place as a result of increasing temperature and overburden pressure. Burial of sediment results in equilibration of unstable mineral phases, and produces a predictable sequence of changes in the clay mineralogy of fine-grained sedimentary rocks. The driving force behind many of these reactions is an increase in temperature caused by geothermal heating. An average geothermal gradient for a stable cratonic basin is approximately 2S°C per km (Girard and others, 1989), and this gradient can be used to estimate temperatures of burial alteration for this study. Paleozoic sediments in the Beardmore Glacier region may have been buried to depths of over

2000 m, based on the thickness of the overlying sedimentary and volcanic/volcaniclastic sequence (Barrett and others, 1986). An additional 1000 m of sill thickness increased the burial depth (David Elliot, personal communication) but maximum burial depths are still shallow when compared to other rapidly subsiding basins. Estimates indicate that mudrocks from the Beardmore Glacier 199 region have been subjected to temperatures in excess of 100°C on the basis of burial diagenesis and geothermal gradient alone.

Thermal alteration due to metamorphic and igneous activity is also a potential influence on the mineral composition of mudrocks in the Beardmore

Glacier region, where Jurassic sills and dikes have caused localized heating of the sediment. When samples are taken in close proximity to intrusive bodies, the total thermal alteration exceeds the background alteration caused by burial diagenesis alone, and temperatures of alteration may approach a maximum of 650°C (see

Chapter III, Organic Carbon Evaluation). Total thermal alteration approaches background diagenetic levels at greater distances from intrusive bodies, producing a continuous spectrum of mineral reactions ranging from low temperature diagenesis to higher temperature thermal alteration.

Burial diagenesis and thermal alteration are discussed together in this section by reviewing the major clay groups and their reaction to post-depositional alteration. The first low temperature mineralogic changes observed in mudrocks are associated with burial diagenesis and the conversion of smectite to more stable mineral forms. Smectites and interstratified illite/smectite are stable at low temperatures, but a change in the mineralogy occurs when temperatures exceed 70°-

90°C (Hower and others, 1976; Jennings and Thompson, 1986; Pearson and Small,

1988; Glasmann and others, 1989). Above this temperature, smectite is converted to illite or interstratified illite/smectite, and the proportion of interstratification continues to decrease with increasing temperature (Perry and Hower, 1970; Eslinger 200 and Sellars, 1981). Interstratified illite/smectite gradually alters to pure illite over a temperature range of 70°C to 210°C, after which pure illite is present (Jennings and

Thompson, 1986). Chemical analysis of this mineralogic change (Hower and others, 1976) shows that the conversion of smectite to illite approximates the following reaction:

smectite + Al+3 + K+ = illite + Si*4

These authors interpret the smectite-to-illite conversion in mudrocks as an essentially closed system, with potassium and aluminum supplied by the decomposition of potassium feldspar (Perry and Hower, 1970; Hower and others,

1976).

Illite undergoes structural and crystallographic changes with increased heating, and these changes provide another method for determining the extent of alteration in sedimentary rocks. As thermal alteration increases, illite becomes more uniformly crystalline, and this change in crystallinity can be measured on x- ray diffractograms of the illite (001) peak. The maximum and minimum temperatures encompassed by illite crystallinity measurement are approximately the same as the range of alteration covered by vitrinite reflectance analysis, so these two measurements can be used as independent indicators of the extent of alteration.

Two different methods have evolved for calculating illite crystallinity. Weaver

(1960) measured the height of the illite 001 peak at 10 A and at 10.5 A, and constructed a relative sharpness ratio based on the 10 A/10.5 A peak heights.

Weaver’s sharpness ratio increases with increasing crystallinity, and correlates well 201 with other alteration indices that are used in mudrocks (Guthrie and others, 1986).

Another method for determining illite crystallinity is the illite crystallinity index summarized by Eberl and Velde (1989), where <2(om clay samples are Mg saturated, x-rayed, and the 001 illite peak width is measured at the peak’s half height. Using this method, the illite crystallinity index (I.C.I.) decreases as alteration increases (Eberl and Velde, 1989). This illite crystallinity index also correlates well with standard methods of measuring alteration in mudrocks, and has been widely used by the petroleum industry (Duba and Williams-Jones, 1983).

Illite polytypes provide another potential method for determining the extent of alteration in clay-rich sedimentary rocks. Polytypes are special polymorphs that form by changing the stacking arrangement in layered minerals. In clay minerals, polytypes are created by rotating octahedral sheets in the a-b plane relative to underlying layers, resulting in new crystallographic structures that retain the original chemical formula (Moore and Reynolds, 1989). Polytypes occur naturally in illite, chlorite, kaolinite and glauconite, although illite polytypes are the only group commonly used in alteration studies.

Poly type formation in illite follows a metastable progression, with lMd and

1M illite present at temperatures below 200°-350°C, and 2M, illite present at temperatures in excess of 200°-350°C (Velde and Hower, 1963). This relationship has been used in sedimentary rocks to map regional patterns of alteration (Frey,

1979) or to document increasing depth of burial (Maxwell and Hower, 1967). A drawback to polytype identification in clay minerals is the presence of interference 202 peaks. Moore and Reynolds (1989) state that "Polytype determinations have been made infrequently because only exceptional samples are sufficiently monomineralic to allow measurements of the required diffraction peaks..." Peak interference with other silicate and phyllosilicate minerals is a potential problem in this study, since the samples analyzed contain a diverse mineral assemblage.

Another important mineralogic change associated with increased heating is the collapse and disappearance of kaolinite. Weaver and Beck (1971) observed that kaolinite decomposition begins at 150°C, and complete collapse of the kaolinite crystal lattice occurs at temperatures less than 200°C. This was confirmed by

Jennings and Thompson (1986), who found that kaolinite was not present in Plio-

Pleistocene sediments heated in excess of 210°C. This relationship makes kaolinite a good indicator of intermediate temperatures of alteration, since the disappearance of kaolinite in an altered sequence may indicate that the 200°C isograd has been exceeded.

With even higher temperatures, diagenetic chlorite and biotite become the stable mineral phases. Thermally altered shales studied by Yau and others (1988) yielded a range of diagenetic products, and different mineral assemblages were correlated with estimated temperatures of alteration. These authors found that chlorite is stable in a zone ranging from 220°-310°C and biotite is stable above

310°C (Yau and others, 1988). In a similar project, Jennings and Thompson (1986) estimated that diagenetic chlorite begins to appear at temperatures greater than 203 180°C. These guidelines are used below to discuss potential sources for the illite and chlorite observed in samples from the Beardmore Glacier region.

The result of these diagenetic changes is a trend toward increased illitization and chloritization in older sedimentary rocks (Keller, 1970). With increasing alteration the mineral assemblage approaches a uniform composition of chlorite, illite and quartz, coupled with concomitant loss of smectite and kaolinite. Weaver and Beck (1971) confirmed these results in a study of cores from the Gulf of

Mexico, and used an assumed geothermal gradient to estimate that mudrocks heated in excess of 300°-400°C arc composed of a simple mineral suite of chlorite, illite and quartz as a result of thermal degradation of less stable phyllosilicate minerals.

Diagenetic and thermal alteration may exert powerful controls on the mineralogy of mudrocks, and any provenance or paleoclimatic interpretations based on the clay mineralogy of Paleozoic sediments must consider these mineralogic changes.

Methods

Many of the samples used earlier to evaluate organic carbon contents and inorganic geochemistry were also selected for mineralogic analysis. Precautions that were observed during field work and sample collection also ensure data integrity during the mineralogic analysis. Samples were quarried from clean, unweathered outcrops to avoid mineralogic changes resulting from surficial weathering, and were packaged individually to avoid cross-contamination between samples. 204 In the laboratory, representative blocks weighing approximately 100 g were ground in a tungsten-carbide ball mill for 10 minutes, and the resulting powder was sieved to 200 mesh to ensure homogeneity of the sample. Air-dried powders were mixed with 10% boehmite (AIO(OH)) by weight to provide an internal standard, and randomly oriented x-ray slides were constructed by back-loading the powder into a nylon holder and strengthening the backing with granular zinc. This results in a flat, homogenous, unoriented mount that is representative of the mineralogy of the larger sample.

Un-glycolated samples were analyzed on a Phillips 3100 XRG x-ray generator using a Phillips (Norelco) stepping goniometer and a Perkins Elmer control unit that stores the digitized data on eight inch floppy disks. This x-ray unit has a theta compensator to correct for low angle beam scatter, a 0.2° receiving slit, and a single crystal graphite monochromator. Gun potential was set at 35 kv and

15 ma, and samples were bombarded with Cu ka radiation. Routine mineral identification was performed by scanning each sample from 3° to 35° 20 using a

0.01° step increment and a 1 second count time per step, and results were plotted at a scale of 1° per inch. Every fifth sample was run twice, and one sample (MKR

6.0 m) was run five times to provide a check of statistical reproducibility.

Appropriate step intervals and count times for the x-ray runs were determined empirically by making repeated runs of a novaculite (pure silica) test sample, and comparing the observed results to the expected results for five peaks that occur in 205 the 65°-70° 20 range. Longer step intervals produced a loss of resolution, while

longer count times did not appreciably increase the accuracy of the run.

A separate slow scan of each sample was used to measure illite crystallinity.

This was accomplished by scanning from 8° to 10° 20 using a 0.01° step interval

and a 5 second count time per step. The increased count time was chosen to

increase the intensity of the illite (001) peak, and results were plotted on a scale of

1/2° per inch to exaggerate the peak shape. Illite crystallinity was calculated by

drawing baselines for the illite peak, and measuring the peak width at half height,

in cm. The shape of the illite peak was estimated and sketched by hand in samples

where background noise or mineral interferences resulted in an asymmetrical (001)

illite peak.

Chlorite was distinguished from kaolinite using a method discussed by

Moore and Reynolds (1989). Chlorite and kaolinite are difficult to distinguish

during routine x-ray analysis because the n^ order reflections of the chlorite 14.2 A

peak and the kaolinite 7.1 A peak are superimposed. Higher order reflections of

these peaks begin to diverge, and the two minerals can commonly be resolved by a

slow scan past the (004) chlorite peak found at 25.1° 20 and the (002) kaolinite

peak found at 24.9° 20 (Moore and Reynolds, 1989). In this study, peak

separation was achieved by scanning from 24°-26° 20 at a step interval of 0.01°

and a count time of 5 seconds per step. Results are plotted at a scale of 1/2° 20 per inch to improve separation of the peaks. Moore and Reynolds (1989) emphasize that this is a non-rigorous solution, and that the only definitive method 206 of identifying these two minerals is a combination of acid dissolution to remove the chlorite, and heat treatment to collapse the kaolinite structure. These detailed procedures were not performed in this study.

Upon completion of the x-ray analysis, peak areas for each mineral were measured using a Tamaya digital planimeter. Each peak was traced three times to provide an average value for the peak area, and relative abundances of each mineral were calculated by comparing individual peak areas to the boehmite peak area.

This produces semi-quantitative mineral abundance values, which can then be compared between samples.

Raw data shown in Appendix C were collected from mineral peaks that do not have constructive interference from other mineral groups. Mineral peaks chosen for analysis in this study include basal diffractions of illite (001) and chlorite (002), the boehmite (020) peak, and the quartz (100) peak. Feldspar relative abundances are more difficult to measure because the most intense feldspar peaks interfere with the peaks of other silicate minerals. Because of this interference problem, several feldspar peaks were measured in an attempt to find a peak or series of peaks that represent the relative feldspar content in an accurate and reproducible manner. A peak labelled "all feldspar," which represents components of plagioclase and potassium feldspar, was measured at 23.5°-23.8° 20, and plagioclase content was measured at 22.5° and 27.79-28.05° 20. Potassium feldspar (as a group) and microcline (specifically) were measured at 26.9°-27.10°

2 0 and 27.52° 20, respectively. 207 Semi-quantitative mineral analysis produces relative abundance values, but it is important to realize that these numbers do not represent the actual concentration of the mineral in each sample. Some minerals are stronger diffractors of the x-ray beam than others, so peak height (and therefore peak area) is not a direct measure of mineral concentration. Numbers produced in this study are used to compare the relative abundances of minerals between samples, but should not be considered estimates of actual mineral abundance or compared to values from other studies.

Results and Discussion

Results of bulk mineralogic analysis

Complete results of mineralogic analysis are presented in Appendix C, and a typical x-ray pattern of a sample from the Beardmore Glacier region is shown in

Figure 51. The mineral suite in each of the samples analyzed is fairly consistent, although relative abundances of the minerals change from sample to sample. Most raw data is presented as a number that represents the peak area for the mineral in question. Kaolinite was simply noted as "present" in the limited number of samples where kaolinite was identified. Interference from the chlorite peak and low abundances of kaolinite preclude accurate measurement of kaolinite peak areas. In general, the mineral pattern is simple and consistent, making mineral identification a straightforward proposition for the majority of the samples analyzed.

Reproducibility of mineral abundance data is summarized in Table 11 and Table 12. Figure 51: Typical x-ray diffraction pattern from the Beardmore Glacier region, Glacier diffractionBeardmorex-raythe pattern Typicalfrom 51: Figure

Intensity (counts per second) 0 0 4 0 0 3 200 100 measurements. Antarctica, showing minerals present and peaks used for peak area peak for usedshowingAntarctica,mineralspeaks present and Sample MKR 6.0 m 6.0 MKR Sample 'C ere ( ) 0 (2 Degrees 20 25 0 3 208 209 Table 11: Reproducibility data for peak area measurements of quartz, boehmite and phyllosilicate minerals. Illite, chlorite, quartz and boehmite peak area measurements are reproducible to within 11% of the mean.

SamplelD Phyllosilicate and Silicate Peak Areas Boehmite Illite Mineral peak examined Illite Chlorite Quartz Peak area Peak width (in degrees 20) 8.9 12.5 20.85 14.49 8.9 TGA41.QLP 0.7 1.8 14.5 4.1 0.2 TGA41.0LP 1.4 1.7 13.0 5.1 0.2 TGA41.0LP 1.6 1.0 19.2 5.0 0.3 Mean 1.2 1.5 15.6 4.7 0.2 Standard deviation 0.4 0.4 2.6 0.4 0.1 Coefficient of variation: 31.3 23.7 17.0 9.5 29.7 MKR6.0LM 11.9 12.7 7.1 4.9 0.3 MKR6.0LM 15.5 10.2 8.5 3.1 0.4 MKR6.0LM 11.8 11.5 7.2 4.3 0.3 MKR6.0LM 12.7 12.1 7.1 5.7 0.3 MKR6.0LM 14.3 12.3 8.3 5.0 0.3 Mean 13.2 11.8 7.6 4.6 0.3 Standard deviation 1.4 0.9 0.6 0.9 0.0 Coefficient of variation: 10.9 7.4 8.2 19.0 7.2 CHI132.6LM 3.6 6.6 7.7 1.6 0.3 CHI132.6LM 5.3 8.5 6.7 2.6 0.4 Mean 4.5 7.6 7.2 2.1 0.4 Standard deviation 0.8 1.0 0.5 0.5 0.0 Coefficient of variation: 19.1 12.6 6.9 23.8 5.7 TRM27.5MM 11.2 16.3 11.1 5.3 0.4 TRM27.5MM 9.4 10.2 9.8 4.0 0.2 Mean 10.3 13.3 10.5 4.7 0.3 Standard deviation 0.9 3.0 0.6 0.6 0.1 Coefficient of variation: 8.7 23.0 6.2 14.0 29.8 MMDI15.5UM 5.5 7.9 6.6 3.4 0.4 MMD115.5UM 4.7 7.1 6.0 3.1 0.4 Mean 5.1 7.5 6.3 3.3 0.4 Standard deviation 0.4 0.4 0.3 0.1 0.0 Coefficient of variation: 7.8 5.3 4.8 4.6 6.3 MTM269.0UM 7.7 12.4 7.8 4.8 0.4 MTM269.0UM 8.1 13.1 8.1 2.7 0.4 Mean 7.9 12.8 8.0 3.8 0.4 Standard deviation 0.2 0.4 0.1 1.1 0.0 Coefficient of variation: 2.5 2.7 1.9 28.0 2.8 MDK209.0F? 4.0 4.6 7.5 3.5 0.3 MDK209.0F? 4.3 5.7 11.0 3.2 0.4 Mean 4.2 5.2 9.3 3.4 0.3 Standard deviation 0.1 0.5 1.8 0.2 0.0 210 Table 11: continued.

SamplelD Phyllosilicate and Silicate Peak Areas Boehmite Illite Mineral peak examined Illite Chlorite Quartz Peak area Peak width (in degrees 2 0 ) 8.9 12.5 20.85 14.49 8.9 Coefficient of variation: 3.6 10.7 18.9 4.5 8.8 MMD283.5LB 2.8 12.7 4.5 3.6 0.3 MMD283.5LB 2.8 10.7 5.9 3.5 0.3 M ean 2.8 11.7 5.2 3.6 0.3 Standard deviation 0.0 1.0 0.7 0.0 0.0 Coefficient of variation: 0.0 8.5 13.5 1.4 6.7 MMD440.5LB 0.8 0.8 6.7 6.5 0.0 MMD440.5LB 0.7 0.7 6.6 5.8 0.0 Mean 0.8 0.8 6.7 6.2 0.0 Standard deviation 0.1 0.1 0.0 0.3 0.0 Coefficient of variation: 6.7 6.7 0.8 5.7 n.v. MPU241.5UB 1.8 0.0 9.8 4.5 0.2 MPU241.SUB 3.4 0.0 10.0 3.7 0.3 M ean 2.6 0.0 9.9 4.1 0.3 Standard deviation 0.8 0.0 0.1 0.4 0.0 Coefficient of variation: 30.8 n.v. 1.0 9.8 14.8 LPP54.5UB 0.0 0.0 8.4 5.6 0.0 LPP54.5UB 0.0 0.0 7.9 4.3 0.0 Mean 0.0 0.0 8.2 5.0 0.0 Standard deviation 0.0 0.0 0.2 0.6 0.0 Coefficient of variation: 0.0 n.v. 3.1 13.1 n.v. Mean coefficient of variation 11.0 11.2 7.5 12.1 12.4 211 Table 12: Reproducibility data for peak area measurements of feldspar minerals. Values for all feldspar and plagioclase (27.79°-28.05° 20) have acceptably low coefficients of variation. Values for plagioclase (22.05° 20), K-feldspar and microcline have high variability, and are excluded from further analysis.

SamplelD Fe dspar Peak Areas Mineral peak examined Plagioclase All Feldspar K- Feldspar Microcline Plagioclase (in degrees 26) 22.05 23.5-23.8 26.9-27.10 27.52 27.79-28.05 TGA41.0LP 1.0 1.2 0.0 2.2 9.7 TGA41.0LP 1.4 0.8 1.5 2.3 8.5 TGA41.0LP 0.9 0.6 1.7 2.8 9.0 Mean 1.1 0.9 1.1 2.4 9.1 Standard deviation 0.2 0.2 0.8 0.3 0.5 Coefficient of variation: 19.6 28.8 71.1 10.8 5.4 MKR6.0LM 1.5 1.1 0.0 1.7 12.0 MKR6.0LM 1.5 0.4 0.0 0.4 11.4 MKR6.0LM 1.0 0.6 0.0 0.0 12.0 MKR6.0LM 1.1 1.1 0.0 0.4 10.5 MKR6.0LM 0.8 0.9 0.0 0.8 10.7 Mean 1.2 0.8 0.0 0.7 11.3 Standard deviation 0.3 0.3 0.0 0.6 0.6 Coefficient of variation: 23.6 34.0 n.v. 87.6 5.6 CHI132.6LM 0.8 0.9 0.8 6.4 4.8 CHI132.6LM 0.5 1.2 0.8 1.1 5.4 Mean 0.7 1.1 0.8 3.8 5.1 Standard deviation. 0.2 0.1 0.0 2.7 0.3 Coefficient of variation: 23.1 14.3 0.0 70.7 5.9 TRM27.5MM 0.7 1.6 0.0 0.7 11.5 TRM27.5MM 0.7 0.7 1.1 0.3 10.5 Mean 0.7 1.2 0.6 0.5 11.0 Standard deviation 0.0 0.4 0.6 0.2 0.5 Coefficient of variation: 0.0 39.1 100.0 40.0 4.5 MMD115.5UM 1.0 0.5 0.2 0.7 4.7 MMD115.5UM 0.4 0.5 0.0 0.9 4.6 Mean 0.7 0.5 0.1 0.8 4.7 Standard deviation 0.3 0.0 0.1 0.1 0.0 Coefficient of variation: 42.9 0.0 100.0 12.5 1.1 MTM269.0UM 0.7 0.3 0.0 0.3 4.6 MTM269.0UM 0.6 0.3 0.0 0.7 7.8 Mean 0.7 0.3 0,0 0.5 6.2 Standard deviation 0.0 0.0 0.0 0.2 1.6 Coefficient of variation; 7.7 0.0 n.v. 40.0 25.8 MDK209.0F? 2.2 2.9 0.0 0.8 14.8 MDK209.0F? 2.0 2.3 0.6 1.4 15.6 Mean 2.1 2.6 0.3 1.1 15.2 Standard deviation 0.1 0.3 0.3 0.3 0.4 212 Table 12: continued.

SamplelD Fe dspar Peak Areas Mineral peak examined Plagioclase All Feldspar K- Feldspar Microcline Plagioclase (in degrees 2 6 ) 22.05 23.5-23.8 26.9-27.10 27.52 27,79-28.05 Coefficient of variation: 4.8 11.5 100.0 27.3 2.6 MMD283.5LB 0.3 1.3 1.0 2.6 1.4 MMD283.5LB 0.0 1.7 0.9 3.6 2.2 Mean 0.2 1.5 1.0 3.1 1.8 Standard deviation 0.2 0.2 0.0 0.5 0.4 Coefficient of variation: 100.0 13.3 5.3 16.1 22.2 MMD440.5LB 0.5 0.8 0.5 0.4 1.1 MMD440.5LB 0.0 0.4 1.0 0.7 2.1 Mean 0.3 0.6 0.8 0.6 1.6 Standard deviation 0.2 0.2 0.2 0.1 0.5 Coefficient of variation: 100.0 33.3 33.3 27.3 31.3 MPU241.5UB 3.2 1.2 0.0 0.1 18.6 MPU241.5UB 2.4 1.3 0.7 0.2 18.1 Mean 2.8 1.3 0.4 0.2 18.4 Standard deviation 0.4 0.0 0.3 0.0 0.2 Coefficient of variation: 14.3 4.0 100.0 33.3 1.4 LPP54.5UB 0.0 2.1 3.5 4.6 0.1 LPP54.5UB 0.0 2.0 1.4 2.8 0.8 Mean 0.0 2.1 2.5 3.7 0.5 Standard deviation 0.0 0.0 1.0 0.9 0.4 Coefficient of variation: 0.0 2.4 42.9 24.3 77.8 M ean coefficient of variation 30.5 16.4 61.4 35.4 16.7 213 Eleven of the fifty samples analyzed were subjected to replicate analysis, and a mean and a standard deviation were determined for each set of replicate samples.

Sample MKR 6.0 m was run five times to obtain a more significant mean and standard deviation. These results are summarized at the bottom of Table 12 and

Table 13 in a statistic called the "mean coefficient of variation." This statistic is calculated using the following formula: (standard deviation -f mean) x 100 = coefficient of variation. The coefficient of variation obtained from analysis of a particular mineral is averaged for a group of samples to determine the mean coefficient of variation. This statistic identifies analyses where the standard deviation is a significant proportion of the mean. For future discussions, peak areas with a coefficient of variation that exceeds 20% are omitted.

Illite, chlorite, quartz and boehmite have coefficients of variation that average 7-12% of the mean in replicate samples, and peak areas from these analyses are considered reproducible. Peak areas from the "all feldspar" peak at

23.5°-23.8° 20 and the plagioclase peak at 27.79°-28.05° 2© have coefficients of variation that average 16% of the mean, and are also judged to be valid methods for measuring feldspar content in this sample set. The plagioclase peak at 22.05°

20 and the microcline peak at 27.52° 20 have high coefficients of variation, and these irreproducible results are omitted from further discussion.

For each reproducible mineral peak, mineral peak areas have been compared to boehmite peak areas within each sample. This generates relative mineral abundance data, and allows relative mineral abundances to be compared between 214 Table 13: Stratigraphic summary of mean relative mineral abundance data for the four studied formations and eight informal subunits. Changes in ratios of quartz to clay indicate higher quartz contents in the Pagoda and Buckley Formations than in the other units.

Formation Boehmite-Nomtalized Peak Areas Illite Chlorite Quartz AU Feldspar Plagioclase to boehmite to boehmite to boehmite to boehmite to boehmite ratio ratio ratio ratio ratio PAGODA lower Pagoda mean 0.8 1.3 2.3 0.2 2.1 upper Pagoda mean 0.9 1.1 3.4 0.8 2.4 Entire Pagoda mean 0.8 1.2 2.9 0.5 2.2 Standard dev.: 0.4 0.6 0.7 0.6 1.5 MACKELLAR lower Mackellar mean 1.9 2.5 2.6 0.4 3.3 middle Mackellar mean 1.6 1.9 1.8 0.3 2.5 upper Mackellar mean 1.4 2.2 2.9 0.5 3.3 Entire Mackellar mean 1.6 2.2 2.4 0.4 3.0 Standard dev.: 1.1 1.4 1.1 0.4 2.0 FAIRCHILD Entire Fairchild mean 1.1 2.1 2.2 0.6 2.7 Standard dev.: 0.4 0.4 0.6 0.2 1.1 BUCKLEY lower Buckley mean 0.8 2.0 2.0 0.3 2.4 upper Buckley mean 0.4 0.3 2.2 0.5 1.8 Entire Buckley mean 0.5 1.0 2.2 0.4 2.1 Standard Dev. 0.5 1.3 0.9 0.4 1.9 215 samples. Relative mineral abundances (peak area ratios) are presented in Appendix

C. Regional (geographic) variations in mineral abundances are evaluated by averaging the mineral abundances at each locality for each formation, and plotting mean relative abundance values on a map. Mineral abundances in the Pagoda,

Fairchild and Buckley Formations do not vary significantly across the study area, and are not shown here. The lack of significant regional variation in these formations supports the hypothesis that fluvial and glacial depositional processes did not exert a noticeable influence on the mineralogy.

Geographic patterns in mineral abundances within the basinal Mackellar

Formation have been examined in more detail by plotting relative quartz abundances (Figure 52) and quartz/(feldspar + clay) relative abundance patterns

(Figure 53) across the depositional basin. These geographic summaries do not show consistent regional variations. Results indicate that transport processes were not the dominant factor in controlling mineral abundances in the Beardmore Glacier region. It is also possible that the transport signature has been so heavily overprinted by diagenetic effects as to be unidentifiable. The combined effects of source area composition, weathering (climatic regime) and secondary alteration have obscured any mineralogic variations that were caused by differential transport, mechanical stability or flocculation of mineral grains during Permian transport and deposition.

Changes in the relative mineral abundance of a mineral through time can be observed by tabulating mean mineral abundance values for the four formations RELATIVE QUARTZ ABUNDANCE MACKELLAR FORMATION 170 E

Figure 52: Geographic distribution of relative quartz abundance values for the Mackellar Formation. All values from each locality are summed and presented as an average. Lack of regional patterns indicates that depositional processes associated with the Mackellar basin are not the dominant control on quartz distribution. 217 RELATIVE QUARTZ TO FELDSPAR AND CLAY ABUNDANCE - MACKELLAR FORMATION

Figure 53: Geographic distribution of relative quartz / (feldspar + clay ) abundance values for the Mackellar Formation. All values from each locality are summed and presented as an average. Lack of regional patterns indicates that depositional processes associated with the Mackellar basin are not the dominant control on quartz, feldspar and clay distribution. studied and eight informal subunits (Table 13). Several trends emerge from this stratigraphic analysis of the mineralogy of fine-grained sediments from the

Beardmore Glacier region. The Pagoda Formation has a higher quartz to clay ratio than any of the other formations studied. This is evident in plots of illite content vs. quartz abundance (Figure 54) and chlorite content vs. quartz abundance (Figure

55). High quartz abundance in the Pagoda Formation is due to a combination of erosional processes associated with glacial movement, and results from strong detrital influence from the underlying source material. As the Carboniferous/

Permian ice sheet scraped over Devonian sandstones of the Alexandra Formation, quartz grains were recycled into the Pagoda diamictite. Well-rounded sand-sized quartz grains are visible in hand specimens of the Pagoda Formation, and support these mineralogic conclusions.

The Buckley Formation has a higher relative quartz to clay ratio than the underlying Mackellar and Fairchild Formations, and significant differences exist between the mineral composition of the lower and upper Buckley Formation informal subunits. The mechanism for the increasing importance of quartz in the

Buckley Formation is different than the mechanism yielding high quartz-to-clay ratios in the Pagoda Formation. In the Buckley Formation, the observed pattern is caused by a progressive decrease in the relative abundance of illite (Figure 54) and a more abrupt decrease in the relative abundance of chlorite (Figure 55). This trend toward decreasing relative abundance of clay minerals through time is shown by 219

Illite vs. Quartz Relative Mineral Abundances

Mackellar

o> 3 1-41

§ 1.2-1 m Fairchild jp £ l.Oi lower Buckley® Pagoda 2 °-8' 3 0.6H upper Buckley

0 . 2 1 ------1------1------1------1------1------1------1------1------2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 Quartz (relative abundance)

Figure 54: Relative abundances of quartz and illite are plotted to demonstrate mineralogic differences between the four formations studied. The glacial Pagoda Formation has the highest quartz content, while quartz becomes proportionally more important in the Buckley Formation as the relative abundance of illite decreases from the Mackellar through to the Fairchild and Buckley Formations. The arrow illustrates this upsection change in mineralogy. 220

Chlorite vs. Quartz Relative Mineral Abundances

2.5' lower Fairchild Mackellar Buckley

2.0-

c 3 X) «3 1.5- (U Pagoda > •a .2 1.0- a> •n upper 3 0.5- U Buckley

0.0 T

Quartz (relative abundance)

Figure 55: Relative abundances of quartz and chlorite are plotted to demonstrate mineralogic differences between the four formations studied. The glacial Pagoda Formation has the highest quartz content, while quartz becomes proportionally more important in the Buckley Formation as the relative abundance of chlorite decreases from the Mackellar through to the Fairchild and Buckley Formations. The arrow illustrates this upsection change in mineralogy. 221 the arrows in Figure 54 and Figure 55. This change produces higher quartz to clay ratios in the Buckley Formation than in the underlying units.

The increase in the importance of quartz in the Buckley Formation is interpreted as input from the volcanic source cited by Isbell (1990) and Barrett and others (1986). Volcaniclastic grains contributed silica to the system during Buckley deposition (Isbell, 1990), resulting in dilution of the detrital clay component and a relative increase in quartz. Changes in the illite abundance from the lower to the upper Buckley Formation are interpreted as an initial ashfall, followed by the introduction of the volcaniclastic grains described by Isbell (1990). Chlorite abundances change more abruptly from the lower units to the upper Buckley

Formation, and may be more directly tied to the input of volcaniclastic sedimentary particles.

These interpretations using mineralogic trends are supported by chemical analyses of the overlying units. Data from the Fremouw Formation (Vavra, 1984) indicates that the SiOz content of the volcaniclastic units is higher than the Si02 content of the underlying Permian sediments, and this is consistent with the observed mineralogic patterns. Geochemical analyses of four airfall tuffs from the

Falla Formation are consistent with the interpretation of volcanic ash input that began during Buckley deposition, since the ash beds have a chemical composition that is similar to the composition of the Buckley Formation. The trend observed on these mineralogic summary diagrams is interpreted as the beginning of volcanic influence. This interpretation is supported by inorganic geochemical data (see 222 Chapter IV) and multivariate statistical analysis that identify the increasing importance of silica in the Buckley Formation. If the high silica content of the

Buckley Formation is due to the interpreted airfall ash input, much of the amorphous silica contributed has probably recrystallized since Permian time. The closed system provided by impermeable mudrocks is interpreted to have preserved the mineralogic and chemical signal of volcanic input in the Buckley Formation.

Kaolinite was observed in a limited number of samples from the Buckley

Formation, and this is interpreted as a paleoclimatic signal that indicates an increase in chemical weathering following the retreat and collapse of the Carboniferous/

Permian ice sheet Kaolinite was not found in samples from the Pagoda, Mackellar and Fairchild Formations, and it was not found in highly altered samples. The absence of kaolinite in the lower units implies that chemical weathering was less effective before Buckley time, and this is supported by the upsection increase in organic carbon content discussed in Chapter IB. It is possible that kaolinite was originally present in other samples that subsequently have been highly altered, removing the kaolinite. The absence of kaolinite in highly altered samples rules out a hydrothermal origin for the mineral, and suggests that kaolinite may have been more common in Permian sediments, but has decomposed in thermally altered samples. 223 Results of illite crystallinity measurements

Complete results of illite crystallinity measurements are presented in

Appendix C. Illite crystallinity has been correlated with vitrinite reflectance measurements in many previous studies (Duba and Williams-Jones, 1983; Guthrie and others, 1986), and a similar comparison is used as a test of the illite crystallinity data generated in this project. A plot of vitrinite reflectance data vs. illite crystallinity measurements for all available samples yield distributions with no apparent pattern (Figure 56). A plot of vitrinite reflectance vs. illite crystallinity for an individual section (section MBO) also yields a random pattern, and rules out the possibility that individual trends have been obscured in the comprehensive diagram

(Figure 57). The reliability of vitrinite reflectance data as an indicator of alteration has been previously established in this study, and section MBO was used as an example of the relationship between vitrinite reflectance and proximity to an intrusive body (Figure 24). The results discussed here and illustrated in Figure 56 indicate that illite crystallinity as measured in this study is not a reliable indicator of thermal alteration caused by proximity to intrusive bodies.

Several factors are responsible for the lack of success in using illite crystallinity measurements as an indicator of the degree of alteration. The foremost problem is the bulk samples prepared for this study. Previous workers have isolated distinct size fractions for illite crystallinity measurement, and usually performed the analysis on a sample of <2pm-sized material. It is also common practice to use oriented mounts, which emphasize the basal diffraction of illite. Figure 56: Plot of vitrinite reflectance data (Ro) vs. illite crystallinityillitevitrinitevs. reflectance(Ro) data of Plot 56:Figure correlation for these two parameters.twothese for correlation measurements for all available data. The random pattern indicates a lack of of lack a indicates pattern random The availabledata.measurementsallfor Illite peak width (cm) 0.05 0.15 0 0.25* 0.35- 0.45 . 20 0.0 - Illitepeak widthRo vs. . 30 . 50 6.0 5.0 4.0 3.0 2.0 Vitrinite reflectance (Ro) reflectance Vitrinite All dataAll

7.0 224 225

Illite peak width vs. Ro Section MBO

0.50

S 0.30

si 0.20

2.0 2.5 3.0 Vitrinite reflectance (Ro)

Figure 57: Plot of vitrinite reflectance data (Ro) vs. illite crystallinity measurements for samples from section MBO. The random pattern indicates a lack of correlation for these two parameters. 226 These differences in analytical techniques were recognized when this project began, but preliminary analyses of the mineralogy of a few samples yielded strong basal illite peaks. Because of these successful results, illite crystallinity data were collected from bulk samples and random mounts during the remainder of the study to see whether useable results could be obtained from these samples. The advantage of using random mounts of bulk samples is that they require significantly less sample preparation time than is necessary to produce oriented mounts of size- fractionated samples.

The presence of a mixture of illites (and possibly interstratified illite-like minerals) from different sources may also contribute to the lack of correlation between illite crystallinity and vitrinite reflectance. Illite peaks generated by x-ray diffraction are theoretically symmetrical, but the peaks observed in these analyses are often broad and diffuse. Samples analyzed in this project have a wide variety of peak shapes and widely varying vitrinite reflectance values even though they have similar peak widths at half height (Figure 58). Symmetrical peaks were sketched by hand to permit the necessary measurement, but this style of peak definition is often subjective and adds to the lack of correlation. Illites that yielded the asymmetrical peaks examined in this study probably contain a combination of detrital illite from a mixture of high grade metamorphic basement sources, and diagenetic illite formed during alteration of Permian sediments. The resulting peak reflects this mixture of illite crystallinities, which may include poorly crystalline authigenic illite, moderately crystalline diagenetic illite, high temperature thermally Figure 58: Examples of illite crystallinity measurement, as measured on bulk crystallinityonillitemeasured measurement, of as Examples 58: Figure Intensity (counts per second) Intensity (counts per second) 120-1 40- 80-1 40- range of grain sizes to the sample.theto sizes grain of range poorly formed peaks are subjective, and use of bulk samples introduces a introducessamples bulk of usesubjective,and are peaks formed poorly onmeasurementswidth Peak sample.eachforlisted valuesare reflectance vitriniteand Samplenumbers mounts.randomlyx-rayorientedand samples Rn = 0.78 = Rn m 6.0 MKR Ro = 4.81 = Ro MDK 209.0 m 209.0 MDK Degrees (20) Degrees ek it =03 cm 0.31 = width peak peak width = 0.30 cm 0.30 = width peak 10 o= 1.50 = Ro m 27.5 BOB MPI 28.6 m 28.6 MPI o= 6.23 = Ro ek it .1 cm 0.31 = width peak peak width = 0.37 cm 0.37 = width peak 227 228 altered illite, interstratified illite/smectite or even interstratified illite/chlorite. Peak

shapes generated by x-ray analysis of illite are not directly related to the Jurassic

thermal alteration, and have no observable relationship to sill distance or sill

thickness.

Results of illite polvtvpe identification

Illite polytype identification was also unsuccessful, and the method of

sample preparation used in this study is one possible reason for the lack of success.

Illite polytype identification is tricky at best because of interference from nearby

diffraction peaks of other minerals, and few workers have succeeded in providing

usable results from geologic sample sets (Moore and Reynolds, 1989). Random

mounts of samples are appropriate for illite polytype analysis, because random

mounts emphasize the non-basal diffractions. The main problem lies with the bulk

nature of the samples used in this study for polytype identification. As stated

before, these samples are a mixture of grain sizes and illitic materials from a

mixture of sources, so the resulting illite polytypes are not clearly a member of one

polytype group. Future studies that employ illite polytype data should use grain size separates that emphasize a particular population of illite crystals.

Conclusions

Mineralogic analysis yields new information about the sediment sources, alteration effects and paleoclimatic conditions that are responsible for the present- 229 day composition of the Pagoda, Mackellar, Fairchild and Buckley Formations.

Mineralogic variations result from a combination of source area and alteration effects, with both factors responsible for differences in chlorite, illite and quartz content

Much of the chlorite, illite and quartz found in the Pagoda, Mackellar and

Fairchild Formations was contributed by a mature metasedimentary, igneous and metavolcanic cratonic source area that supplied detrital sediment to the Beardmore

Glacier region during Permian time. The Pagoda Formation received a supply of mechanically weathered detrital quartz from the underlying Alexandra Formation, while the Mackellar and Fairchild Formations received sedimentary detritus from a combination of physical and chemical weathering of a mature illite, chlorite and quartz-rich source area. A likely source of detrital sediment for the Mackellar and

Fairchild Formations was the metasedimentary and metavolcanic craton. This source is interpreted to have changed during deposition of the Buckley Formation, resulting in increased proportions of quartz to clay. The new source area is interpreted to be a volcanic arc that is related to the initiation of the foreland basin system discussed by Collinson (1991).

Jurassic thermal alteration continued the trend toward mineralogic maturity and the predominance of high temperature forms of illite and chlorite. Trace amounts of kaolinite in unaltered samples from a single section of the Buckley

Formation at the Helm Glacier record an increase in chemical weathering, and support previous interpretations of climatic warming prior to Buckley time. These 230 samples were preserved in a fortuitously unaltered sedimentary section, and are interpreted to be representative of wider temperate, humid climatic and weathering conditions that existed during Permian time.

Detailed study of illite crystallinity and illite polytypes was not effective in this sample set. The highly indurated nature of mudrocks from the Beardmore

Glacier region precludes disaggregation and analysis of discrete size fractions, and those procedures are necessary for successful illite crystallinity and illite polytype analyses. Indurated mudstones used in this study are best suited to bulk mineralogic analysis, where the results are interpreted in terms of general relationships to source areas, paleoclimate and alteration of the original mineralogy. CHAPTER VI

LOWER TRIASSIC PALEOSOLS

Introduction

The study of fossil soils provides information about ancient climates and

general environmental conditions during deposition of ancient rock units. In order

to gain such information, Permian and Triassic paleosols (fossil soil horizons) were

identified, described and collected from outcrops in the Beardmore Glacier region,

Antarctica. The units examined in this part of the study include the Permian

Buckley Formation and the Triassic Fremouw Formation. The depositional

environment for each of these formations includes fluvial channels and overbank

floodplains (Barrett et. al., 1986; Isbell, 1990). Weakly to moderately developed

paleosols are found in the floodplain sediments which were deposited on the

margins of the ancient river systems.

Field study

Field identification of Triassic paleosols relied heavily on the presence of rooted horizons (Retallack, 1990). At one Permian locality, weak soil profile

development was observed in addition to heavy rooting, which also indicates the

231 232 presence of an ancient soil. During the field operations, 70 samples were collected from 13 measured sections at 5 localities (Figure 59). Seven sections were measured from the middle Fremouw Formation, four were measured in the upper

Fremouw Formation, one section included the Buckley and the lower Fremouw formations, and one section was measured in the upper Buckley Formation.

Multiple sections were measured at several of the localities, allowing description of both lateral and vertical variations in the paleosols.

Results

Weakly developed inceptisols (Retallack, 1990) are common in the gray- green mudstones that were deposited on the floodplains of the Permian and Triassic river systems. Crevasse splays, channel migration, and overbank flooding each contributed pulses of coarser sediment to the floodplain, resulting in frequent burial of immature floodplain soils. New soils subsequently developed on the new land substrate, resulting in stacked successions of buried soils. A typical stratigraphic succession containing paleosols (Figure 60) illustrates the influence of channel systems on floodplain deposits of the Fremouw Formation. Sand bodies ranging from sixty cm to two m thick have erosional bases and were deposited by channel systems, and thinner sand beds are the result of crevasse splays or flooding events

(Isbell and Mcdonald, in press). Paleosols from the Beardmore Glacier area are weakly developed as a result of their proximity to fluvial channels and frequent rapid burial of the developing soils. 233

Figure 59: Location of the study area and paleosol sections that were measured, collected and described during the 1990/1991 field season. (MAR denotes Mount Ackemar locality, GVA, GVB and GVC are Gordon Valley localities, WLG denotes Wahl Glacier, and MKP is a measured section on Mount Kirkpatrick). 234 Triassic Paleosols Gordon Valley, Antarctica

15 m. - i Shale: Green-gray mottled with dark red, carbonaceous

Sandstone: Fine to medium grain, trough cross beds, erosional 14 m. - base

Slltatone: Light green-gray mottled with red-gray, vertical roots 2-4 cm. in diameter abundant at 13 m. - base, relict bedding becomes more common toward top

Shale: Dark gray to green-gray, 12 m . - slightly silty, blocky, trace silicilied plant debris, trace line (<2 mm. diameter) horizontal and vertical roots

11m.— Shale: Red-gray mottled with light gray, blocky

Shale: Dark gray, slightly silty, carbonaceous 10 m. Shale: Red-gray with mottles of light gray, fine horizontal roots

Slltatone: Green-gray, rippled at base, fines upward, relict 9 m. — bedding and vertical roots common throughout, roots are <3 mm. diameter a * k A Interbedded fine grained sandstone and aandy S m. slltatone: rippled

Sandstone: Fine to medium grain, trough cross beds, erosional base Shale: Light gray to green-gray, 10- 15% vertical and horizontal roots 7 m. _ <3 mm. in diameter, slightly silty

Figure 60: Typical paleosol section from the Triassic Fremouw Formation in the Beardmore glacier region. Vertical roots appear to be more common in silty beds adjacent to the sandy channel deposits. This suggests that conditions of high sediment supply favored plants with rapid vertical growth. 235 Permian and Triassic paleosols examined in this study are generally thin, homogeneous, and poorly developed, so the effects of soil forming processes appear to have been relatively uniform during that time. Possible controls on paleosol development are sedimentation rate, type of vegetation present, sediment (substrate) grain size and composition, climate, and water table level. Root patterns within the paleosols may provide information about the role of each of these factors in paleosol development. Roots are oriented both vertically and horizontally, and range in size from 10 cm long and 2 cm thick to 0.5 cm long and 2 mm thick.

Most roots are 2 to 4 cm long, and 3 to 5 mm thick. Additional work may help to determine which of the controls on soil forming processes have contributed to the root patterns that were observed in the Beardmore Glacier area.

Smaller scale structures are also visible in some heavily rooted samples.

SEM microanalysis shows small carbonized fragments 0.1 to 0.3 mm thick which branch laterally from mineralized vertical roots that are 2 to 3 cm in diameter

(Figure 61). These fragments are interpreted to be compressed root hairs.

Enigmatic crushed tubules of smaller size have also been observed, and may provide information about soil-forming processes during Permian and Triassic time.

Additional information about micromorphology of the soils will also be gathered from thin section petrography.

In summary, the paleosols that were observed in the Beardmore Glacier area are relatively well exposed but poorly developed. Widespread lateral and vertical exposures within single extensive outcrops hold excellent promise for further 236

Figure 61: SEM photograph of small-scale root development in Triassic paleosols. Vertical root at the top of the photograph (highlighted with dashed line) is 1 cm in diameter, mineralized, and perpendicular to bedding. Horizontal root hairs 0.1 to 0.3 mm in diameter project outward from the vertical root (see arrows), are carbonized, and lay parallel to the bedding surface. 237 detailed study of lateral and temporal variation in paleosol development. The poor development of Permian and Triassic soils is probably due to rapid sediment supply, and may also have been influenced by the type of vegetation present or the depth to the water table. CHAPTER VII

SUMMARY AND CONCLUSIONS

Several different analytical approaches have been used to provide information about provenance, paleoclimatic history and alteration of Permian mudrocks from the Beardmore Glacier region. Each method adds an additional piece of information to the larger picture, and the collective results can be used to describe conditions that relate to the collapse of the Carboniferous(?)/Permian ice sheet and a change in source area that is interpreted as the onset of contemporaneous volcanism. These paleoclimatic and provenance changes can be determined in spite of a range of diagenetic and thermal alteration that commonly obscures the original chemical and mineralogic signal.

Sedimentoloev

Sedimentology and field relations of the Pagoda, Mackellar, Fairchild and

Buckley Formations reveal details about depositional environments and sources of sediment during Permian time. Glacial diamictites of the Pagoda Formation preserve evidence for multiple advance and retreat cycles of the ice, and waning phases of the ice are indicated by the presence of glacial outwash and fine-grained sediments deposited in meltwater ponds (Miller and others, 1989; see Chapter IE).

238 239 Granite, quartzite, chert and metasedimentary clasts in the Pagoda Formation were derived from underlying Devonian sandstones of the Alexandra Formation and a mixed igneous and metasedimentary source that was probably the Byrd, Beardmore and Nimrod Groups.

The Mackellar Formation was deposited by low gradient fresh-water deltas that prograded into an elongate interior basin that lay on the Paleopacific margin of

Antarctica (Collinson and Miller, 1990). Sediment-laden streams contributed detritus to the shallow basin, with paleocurrent directions that indicate a cratonic source for the clastic material. For the majority of the Beardmore Glacier region, the source area was to the northwest, and consisted of basement metasediments and metavolcanics that belong to the Beardmore Group. Minor contributions from the

Byrd Group and Granite Harbour intrusives were also supplied to the Mackellar depositional system. Paleocurrent directions in the southern part of the study area indicate a slightly different cratonic source area which was located more to the south. Basement rocks that served as the source in this region include mixed metasediments and metavolcanics of the Nimrod Group and Granite Harbour intrusives that outcrop in the Miller Range and Geologists Range.

Heavy sediment influx caused rapid infilling of the Mackellar Basin and subsequent progradation of braided stream facies of the Fairchild Formation. Most of the fine-grained sediment was removed from the Fairchild braided stream systems by reworking, although a few rare shale and siltstone beds were available for sampling and analysis. Paleocurrent directions and trends that existed 240 during deposition of the Fairchild Formation are similar to paleocurrent directions

described for the Mackellar Formation: most of the Beardmore Glacier region

received sediments derived from the Beardmore Group (exposed to the northwest),

with minor input from the Byrd Group and Granite Harbour Intrusives. In the

southern part of the study area, clastic sediment may have been derived from

outcrops of the Nimrod Group and Granite Harbour Intrusives that occur along the

edge of the Polar Plateau.

The Buckley Formation is divided into informal lower and upper members

on the basis of the occurrence of volcaniclastic sediment. Buckley sediments were

deposited in braided stream systems that contained a complex group of

subenvironments including ponds, swampy areas, multi-layered channel deposits

and overbank fines (Isbell, 1990). Paleocurrent directions and potential source

areas for the lower Buckley Formation are the same as those described above for

the Mackellar and Fairchild Formations, with paleocurrents indicating sediment contribution from source areas that lay to the northwest A paleocurrent reversal at the boundary between the lower and upper Buckley Formations supplied an influx of material from a new, southeasterly source area that had not previously contributed sediment to the region.

Organic carbon

Several methods of organic carbon analysis provide additional information about the sources, paleoclimatic setting and alteration of sediments in the 241 Beardmore Glacier region. Vitrinite reflectance values can be used to characterize the alteration of the sediments, and indicate that samples have been subjected to a range of alteration. Least-altered samples have Ro values that correspond to burial diagenesis, but these samples are rare, and only occur in the far northern and far southern regions of the study area. Most samples were subjected to elevated background heating, giving them an average Ro value of 2.47 Ro (estimated temperatures near 200°C) and samples in close proximity to sills were heated to Ro levels greater than 6.0 (temperatures in excess of 600°C). Stratigraphic variations in mean Ro values are insignificant, but regional variations identify a band of intense alteration that runs across the central part of the study area, and corresponds with the occurrence of a band of thicker dolerite intrusions. Vitrinite reflectance of individual samples is related to the distance between that sample and the nearest intrusive body, and this study indicates that vitrinite values approach the background level at approximately one sill thickness away from the sill.

The high level of heating that was observed in highly altered organic carbon compounds does not appear in examinations of mineralogy stability. Slower equilibration of the mineralogic component results in a clay mineral assemblage that is indicative of lower maximum temperatures of alteration than the estimates suggested by the organic carbon component.

Kerogen typing indicates a terrestrial source for carbon compounds recovered from the Pagoda, Mackellar, Fairchild and Buckley Formations. Most of the kerogen is detrital, and was supplied by land plants that colonized the margins 242 of the Mackellar basin or Buckley stream systems. The Pagoda Formation may also contain recycled kerogen from older sedimentary rocks, and a slight increase in the abundance of amorphous/alganitic kerogen in the lower Mackellar Formation is interpreted to record a pulse of planktonic primary productivity in the Mackellar

Basin. Carbon/sulfur ratios confirm the terrestrial nature of the carbon compounds, as do 8l3C isotopic ratios from calcitic concretions in the Mackellar Formation.

The abundance of total organic carbon in Beacon sediments is controlled by productivity of the original depositional environment and the extent of thermal alteration. Organic carbon content is reduced near sills, and decreases drastically within half the sill distances from the sill. At distances greater than one sill thickness away from the sill, organic carbon content reaches a background level that is not controlled by localized thermal alteration.

Stratigraphic variations in T.O.C. content provide information about changing climatic conditions in the Beardmore Glacier region. Organic carbon contents are summarized and interpreted below:

• Pagoda Formation: Organic carbon content in the Pagoda Formation averages 0.20%, which is consistent with the glacial origin and low productivity of the cold environment where this unit was deposited.

• Mackellar Formation: The Mackellar Formation has a mean T.O.C. content of 0.33%, which probably reflects early but sparse colonization by land plants on the margins of the Mackellar Basin. 5 lsO isotopic values (Lord and others, 1988) confirm the effect of a heavy meltwater influx during deposition of 243 the Mackellar Formation, and suggest that the climate was influenced by the collapse of the ice sheet during deposition of the Mackellar Formation.

* Fairchild Formation: Mean organic carbon content in the Fairchild

Formation is 1.06%, but the organic content is highly variable and highlights the abnormally high T.O.C. contents found at section MBO in the southern part of the study area.

• Buckley Formation: Organic carbon in the Buckley Formation averages

21.64%, and is highly variable due to the occurrence of several different facies within the braided stream depositional environment Within each facies, the variability in carbon content is lower. Swamp and ponded environments each have characteristic organic carbon contents, although floodplain facies have T.O.C. values that are highly variable and overlap with values from ponded deposits and channel fill. Organic carbon contents of coal (swampy) facies in the Buckley

Formation range from 40-60% T.O.C. due to the low sedimentation rates relative to the rest of the floodplain facies and the higher preservation potential in anoxic swamps. Overbank ponded deposits contain 13-38% T.O.C., and floodplain facies contain 0.2-13% T.O.C. Higher organic carbon contents in the Buckley Formation are interpreted to result from climatic warming and attendant plant recolonization and growth that followed the collapse of the Carboniferous(?)/Permian ice sheet. 244 Inorganic geochemistry

Permian mudrocks have been examined to determine whether thermal alteration, preferential association with organic carbon compounds or grain size effects exert a controlling influence on chemical composition in the Beardmore

Glacier region. Results indicate that the distribution of major, trace and rare earth elements in Permian mudrocks is relatively unaffected by thermal alteration. Most elements show little or no correlation with vitrinite reflectance or proximity to intrusive bodies, indicating that thermal alteration does not exert a strong influence on chemical composition. Although this relationship is true for most elements, the elements Fe, Mg, Mn and Na are slightly enriched in mudrocks that lie close to intrusive bodies, and probably experienced minor mobilization during the emplacement of Jurassic sills and dikes.

Bivariate plots indicate that elemental distributions are also unaffected by association with organic carbon. Most elemental abundances are negatively correlated with organic carbon content, suggesting a dilution effect as organic carbon content increases. This negative correlation holds true for the transition metals Sc, V, Cr, Co, Ni, Cu and Zn, which are known for their affinity for organic compounds. Detailed analyses of elemental distributions and organic carbon contents in the Buckley Formation confirm that these elements do not complex with organic carbon, and suggest that, except for a dilution effect, organic matter does not significantly affect the bulk chemistry. 245 Sediment grain size and mineralogy have been found to exert a strong control on elemental distribution in mudrocks. These effects have been identified by plotting elemental abundances vs. the abundance of Fe, A1 and Si. Fe and A1 represent an association with phyllosilicate minerals and fine grain size, while Si represents an association with coarser grained silicate minerals. Using this approach, the elements Mg, Ti, K, Sc, Mn, Zn, Th and La are identified as having an association with finer grained clay minerals, and Na and Hf are correlated with coarser grained elastics. The elements Ca and P are not strongly associated with either mineralogic fraction, and are interpreted to have been carried by an non­ silicate component.

After identifying the effects of grain size on geochemistry, additional patterns can be explained by considering differences in provenance between the

Buckley Formation and the lower units. In the Buckley Formation, Si and A1 concentrations are high, and Fe, Mg, Mn and transition metal abundances are low.

These patterns are in addition to those caused by grain size and mineralogic effects, and are not inconsistent with an influx of Si-rich sediment during Buckley deposition. Abundance ratios of Fe, Mg, Mn Si and A1 derived from Tuff samples collected from the Falla Formation (Barrett and others, 1986) are very similar to chemical abundance ratios generated from lower and upper Buckley sediments.

This is also consistent with the interpretation that an early siliceous ash fall contributed sediment to the Buckley Formation before the arrival of detrital volcaniclastic grains described by Isbell (1990). Major element ratios were not 246 effective in identifying the provenance change or chemical affinities of Buckley sediments.

Multi-element ratios of elements are also useful as a provenance tool.

Geographic patterns indicate that the Pagoda, Mackellar and Fairchild Formations in the southern part of the study area have lower Al20/T i0 2 and K20/Na20 ratios than the remainder of the study area. This is interpreted as a chemical signal reflecting the supply of Nimrod Group metasediments and Granite Harbour intrusives to the southern region. These sources appear to be TiOz rich and K20 poor, although this conclusion is speculative. The C.I.A. also increases upsection in the southern part of the study area, and this is interpreted as a climatic signal. Low surface slopes

(gradient) in the southern sections resulted in long residence time and allowed chemical weathering processes to reach their full potential, resulting in increases in

C.I.A. values as the ice sheet retreated, the climate warmed and chemical weathering increased.

Stratigraphic changes in elemental ratios also provide data about changes in sediment supply and weathering intensity. Si(yAl 20 3 ratios increase in the upper

Buckley Formation, and are interpreted as recording an influx of Si-rich (possibly volcanic) sediment that differed from the earlier metasedimentary, metavolcanic and plutonic sediment that was derived from older cratonic material. Al20/T i0 2 ratios also increase upward, and are interpreted as part of the trend toward more siliceous input and less basic or mafic sediment supply. I^O/NajO and KjO/CaO+NajO ratios illustrate an upsection increase in KzO content that may be a climatic effect 247 induced by preferential weathering of unstable plagioclase feldspars, although an upward increase in potassium supply cannot be ruled out.

Multivariate statistical analyses of the geochemical data confirm some of the previous conclusions about chemical patterns in Beardmore sediments. Cluster analysis identifies the Buckley and Mackellar Formations as chemically distinct, and principal component analysis identifies organic carbon as a dominant end- member in the major element distribution. When the chemical data are normalized to remove the effects of organic carbon, principal component analysis indicates that

Si and K are important components of the Buckley Formation. This supports earlier conclusions based on element ratios, including the hypothesis that a new silica-rich source area supplied detrital sediment during deposition of the Buckley

Formation. Mg, Fe and A1 are important chemical components of the lower units, again agreeing with earlier conclusions about the role of a more basic sediment source during deposition of the Pagoda, Mackellar and Fairchild Formations.

Principal component analysis confirms that most elements were not mobile during thermal alteration. The close correlation between elemental assemblages in altered and unaltered sample sets indicates a lack of elemental mobility, with the possible exception of iron distribution near thick sills. Multivariate statistics are a powerful tool for identifying covarying associations of elements, and confirm many of the conclusions made earlier on the basis of simple bivariate plots. 248 Mineralogy

Mudrock mineralogy in the Beardmore Glacier region is controlled by source area characteristics, alteration processes, including thermal effects, and climatic/weathering processes. Source area contributions are a dominant factor, and the mineralogy of Beacon sediments reflects the quartz, chlorite and illite-rich nature of the metasediments, metavolcanics and igneous intrusions that contributed detrital sediment to the study area. Thermal alteration is also a strong influence, and thermal effects have altered the mineralogy since Permian time. Climatic effects are associated with weathering and the intensity of weathering processes that produce clay minerals. The effects of weathering processes and climatic influence are less obvious than provenance or thermal alteration, but weathering effects are evident as climatic indicators in the Beardmore Glacier region.

Clay minerals can be used as stability indicators to estimate temperatures of alteration for Beacon sediments. A scarcity of kaolinite may indicate that some sediments originally contained kaolinite, and were heated in excess of 200°C. Illite polytypes and illite crystallinity were not effective indicators of alteration as a result of the sample preparation methods used in this study. In spite of these problems, the general occurrence and stability of clay minerals agree well with temperature estimates based on vitrinite reflectance or proximity to intrusive bodies.

The major climatic indication provided by clay mineral analysis is the suggestion that chemical weathering effects became a noticeable factor during deposition of the Buckley Formation. This is consistent with the overall model of 249 ice sheet decay during deposition of the Pagoda, Mackellar and Fairchild

Formations, and climatic warming that may have approached temperate conditions

during deposition of the Buckley Formation. Kaolinite can also be a hydrothermal

mineral, but the occurrence of kaolinite in samples with Ro values less than 1.0

supports the suggestion that kaolinite is a weathering product, associated with

increased rainfall and wanner climatic conditions. Sources for the illite and

chlorite-rich detritus that is common in the Pagoda, Mackellar and Fairchild

Formations probably included mineralogically mature metasediments and

metavolcanics of the Precambrian Beardmore Group, with lesser contributions from

the Byrd Group, Granite Harbour Intrusives and Nimrod Group. Sediment supply

became more siliceous during Buckley deposition, as evidenced by increasing ratios

of quartz to illite or chlorite. The increase in Si02 was described previously in the

section on inorganic geochemistry, and now a corresponding quartz increase is evident in the mineralogy. These results indicate that an influx of silica-rich

sediment began during deposition of the Buckley Formation, and this is interpreted

as a provenance change related to the influx of volcanic rock fragments described

by Isbell (1990). An early ash-fall component may be responsible for increases in

silica in the lower Buckley Formation, and if this hypothesis is correct, indicates that volcanism began before the main detrital pulse reached the Beardmore Glacier region. 250 Lower Triassic Paleosols

Paleosols provide an additional method for examining ancient depositional environments, climates and weathering conditions. Weakly to moderately developed paleosols from the Fremouw Formation formed on immature floodplains, and were strongly influenced by sedimentary processes that were associated with

Fremouw stream systems. Flood events contributed pulses of sediment to the area adjacent to the stream channel, resulting in burial of old soil horizons and subsequent initiation of new soil layers. Soils did not have an opportunity to become strongly developed before the next flood event buried the floodplain and initiated a new sequence of soil development. Sediment influx probably provided the limiting factor in paleosol development.

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ORGANIC CARBON ANALYSES

BEARDMORE GLACIER REGION, ANTARCTICA

267 268 Table 14: Results of vitrinite reflectance analysis. The first three characters of each sample name indicate the section of origin, and informal subunits for each formation are designated by the following abbreviations: LP= "lower" Pagoda, UP= "upper" Pagoda, LM= "lower" Mackellar, UM= "upper" Mackellar, LF= "lower" Fairchild, UF= "upper" Fairchild, LB= "lower" Buckley and UB= "upper" Buckley. Numerals in the sample name report the height above the base of the section.

Vitrinite Comments Number of Standard Data Quality: Reflectance Measurements Deviation Acceptable or Sample (Ro) (n) Unacceptable MMP1.5LP coked 0 u MTM129.0LP 2.81 coked 9 0.21 u TCA41.0LP 3.54 1 0.00 u AO values. Mean: 3.10 Acceptable values. Mean: n a . Standard dev.: 0.30 Standard dev.: n a . MMP74.5UP barren 0 U MTM186.2UP 3.18 25 0.25 A M TM2I3.5UP barren 0 U TGA96.7UP 3.07 10 0.27 A All values, Mean: 3.13 Acceptable values, Mean: 3.13 Standard dev.: 0.06 Standard dev.: na. Entire Pagoda AO values, Mean: 3.12 Acceptable values, Mean: 3.13 Standard dev.: 0.21 Standard dev.: n a . MKR6.0LM 0.78 11 0.14 A MMA6.6LM barren 0 U TRMO.OLM 1.21 20 0.11 A CPZ123.4LM 3.10 3 0.50 U TGA151.7LM 3.10 1 U TGA160.0LM coked 0 u M B038.5LM 3.90 23 0.41 A CHI132.6LM 3.92 2 0.81 u MDK10.7LM coked 0 u MDK20.5LM 5.44 5 0.87 u AO values, Mean: 2.68 Acceptable values. Mean: 1.96 Standard dev.: 1.73 Standard dev.: 1.38 MKR42.2MM 0.96 17 0.10 A MMQ4.3MM 2.38 10 0.22 A MMQ33.0MM 2.34 7 0.21 A MMA59.8MM 3.02 coked 3 0.58 U MMC49.1MM 2.84 8 0.31 A MMC74.8MM barren 0 U MMD11.0MM 2.02 6 0.26 A MMD27.0MM 1.93 31 0.22 A 269

Table 14: (continued).

Vitrinite Comments Number of Standard Data Quality: Reflectance Measurements Deviation Acceptable or Sample (Ro) 0 0 Unacceptable TRM27.5MM 1.37 18 0.21 A CPZ145.9MM 2.64 18 0.18 A MTM 2462M M 2.82 19 0.34 A TGA173.0MM 3.70 2 0.42 u M B067.8M M 3.21 25 0.33 A CHU78.5MM 2.24 coked 8 0.38 U All values, Mean: 2.42 Acceptable values. Mean: 2.25 Standard dev.: 0.72 Standard dev.: 0.66 MKR58.5UM 1.26 19 0.17 A MM A732UM 3.44 20 0.33 A MMC117.SUM 3.00 15 0.26 A MMD75.5UM 2.29 28 0.16 A CPZ176.1UM 2.78 16 0.23 A MTM269.0UM 2.99 23 0.30 A MBO88.0UM 2.86 25 0.23 A MBO104.0UM 2.23 30 0.20 A MBO125.0UM 1.71 7 0.15 A MDK119.0UM 5.40 4 2.30 A All values. Mean: 2.80 Acceptable values. Mean: 2.80 Standard dev.: 1.07 Standard dev.: 1.06 Entire Mackellar All values, Mean: 2.61 Acceptable values, Mean: 2.55 Standard dev.: 1.18 Standard dev.: 124 MMA87.0LF 3.21 24 0.21 A MMD115.5L7F 2.11 25 0.21 A TRM71.6LF 1.66 22 0.13 A All values. Mean: 2.33 Acceptable values. Mean: 2.33 Standard dev.: 0.65 Standard dev.: 0.65 TGF136.0F coked 0 U MBO170.0UF 2.23 25 0.17 A MDK209.0F? 4.81 2 0.64 U All values, Mean: 3.52 Acceptable values. Mean: 2.23 Standard dev.: 1.29 Standard dev.: n a . Entile Fairchild A ll values, Mean: 2.80 Acceptable values, Mean: 2.30 Standard dev: 1.12 Standard dev.: 0.56 MMD270.0LB 0.70 25 0.15 A MMD283.5LB 0.93 13 0.15 A MMD295.5LB 0.38 27 0.04 A MMD318.5LB 0.50 30 0.07 A 270 Table 14: (continued).

Vitrinite Comments Number of Standard Data Quality: Reflectance Measurements Deviation Acceptable or Sample (Ro) (n) Unacceptable MMD384.0LB 0.48 31 0.05 A MMD417.0LB 1.01 14 0.15 A MMD440.5LB 2.09 45 0.19 A TGF218.0LB coked U MPI28.6LB 6.23 coked 6 0.86 U MA614.4LB coked 0 u MA645.2LB 2.42 17 0.21 A MA6131.2LB 3.46 29 0.17 A BOB27.5LB 1.50 25 0.12 A BOB89.8LB 1.40 29 0.14 A BOB116.1LB 1.32 25 0.13 A All values. Mean: 1.60 Acceptable values, Mean: 1.35 Standard dev.: 1.56 Standard dev.: 0.88 WLG5.0UB 2.34 21 0.15 A WLG58.0UB 1.91 19 0.09 A MPI53.1UB 2.50 coked 5 0.36 U MPI54.0UB 3.26 coked 4 0.55 U MPU40.4UB 2.53 24 0.33 A MPU117.3UB 3.15 21 0.20 A MPU159.4UB 2.57 25 0.25 A MPU183.8UB 2.65 26 0.18 A MFU214.2UB 3.87 30 0.20 A MPU241.5UB 3.25 25 0.34 A MTR13.1UB 4.36 30 0.42 A MTR61.1UB 3.31 30 0.22 A MTR130.5UB 3.13 29 0.28 A MTR159.5UB 2.41 30 0.26 A MTR203.7UB 1.39 30 0.13 A MA551.7UB 3.49 3 0.57 A MA5114.1UB 3.47 25 0.23 A MAS152.0UB 4.94 50 0.23 A MA49.2UB 2.30 2 0.18 A MA437.0UB 2.93 24 0.28 A LPP28.0UB 2.96 6 0.50 A LPP54.5UB 2.67 10 0.38 A All values, Mean: 2.97 Acceptable values. Mean: 2.98 Standard dev.: 0.77 Standard dev.: 0.80 Entire Buckley All values, Mean: 2.44 Acceptable values, Mean: 2.37 Standard dev.: 132 Standard dev.: 1.15 271 Table 15: Results of organic carbon analyses. Sample names follow the convention described in Figure 6. Individual organic carbon contents have high variability, but averaged values show an upsection increase in T.O.C.

Average Sample Altered Total Carbon (%) Inorganic Carbon (%) Total or Replicate nms Mean Replicate nms Mean Organic Unaltered C arton (%) MMP 1.5 LP A 0.1 0.1 0.1 0.1 0.0 0.0 0.0 0.1 MMP 23.5 LP A 0.1 0.1 0.1 0.0 0.0 0.0 0.1 CPZ 16.3 LP A 0.0 0.0 0.0 0.0 0.0 0.0 0.0 CPZ 46.1 LP A 0.1 0.1 0.1 0.0 0.0 0.0 0.1 MTM 129.0 LP U 0.2 0.3 0.2 0.0 0.1 0.0 0.2 TGA 1.0 LP U 0.1 0.1 0.1 0.0 0.0 0.0 0.1 TGA 31.0 LP U 0.0 0.0 0.0 0.0 0.0 0.0 0.0 TGA 41.0 LP U 0.2 0.2 0.2 0.2 0.2 0.0 0.0 0.0 0.0 0.0 0.2 TGA 86.0 LP U 0.2 0.2 0.2 0.0 0.0 0.0 0.2 "lower" Pagoda Formation Mean: 0.11 Standard deviation: 0.06 MMP 74.5 UPA 0.0 0.0 0.0 0.0 0.0 0.0 0.0 MMC 17.6 UP A 0.1 0.1 0.1 0.0 0.0 0.0 0.1 MTM 167.0 UP U 0.3 0.3 0.3 0.3 0.0 0.0 0.0 0.3 MTM 186.2 UP U 0.5 0.5 0.5 0.2 0.2 0.2 0.4 MTM 213.5 UP U 0.4 0.4 0.4 0.0 0.0 0.0 0.3 TGA 96.7 UP U 0.3 0.2 0.3 0.0 0.0 0.0 0.3 MBO 0.2 UP A 0.1 0.1 0.1 0.0 0.0 0.0 0.1 MBO 9.5 UP A 0.1 0.1 0.1 0.0 0.0 0.0 0.1 CHI 91.0 UP U 0.1 0.1 0.1 0.0 0.0 0.0 0.1 CHI 108.8 UP U 0.3 0.3 0.3 0.0 0.0 0.0 0.3 "upper" Pagoda FormaP on Mean: 0.21 Standard deviation: 0.11 ENTIRE PAGODA FORMATION: MEAN: 0.16 STANDARD DEVIATION: 0.11 MKR 6.0 LM U 0.4 0.4 0.4 0.5 0.4 0.0 0.0 0.0 0.0 0.0 0.4 MKR 12.4 LM u 0.3 0.3 0.3 0.1 0.1 0.1 0 2 MMA 6.6 LM A 0.0 0.0 0.0 0.0 0.0 0.0 0.0 MMA 14.2 LM A 0.0 0.0 0.0 0.0 0.0 0.0 0.0 MMC 18.7 LM A 0.0 0.0 0.0 0.0 0.0 0.0 0.0 MMC 20.5 LM A 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 TRM 0.0 LM U 0.5 0.5 0.5 0.1 0.1 0.1 0.4 TRM 11.5 LM U 0.5 0.5 0.5 0.1 0.1 0.1 0.4 CPZ 117.9 LM A 0.2 0.2 0.2 0.0 0.0 0.0 0.0 0.0 0.2 CPZ 123.4 LM A 0.2 0.2 0.2 0.0 0.0 0.0 0.0 0.0 0 2 272

Table 15: (continued).

Average Sample Altered Total Carbon (9b) Inorganic Carbon(%) Total or Replicate runs Mean Replicate runs Mean Organic Unaltered Cartoon (%) MTM 216.7 LM U 0.6 0.6 0.6 0.6 0.6 0.3 0.3 0.3 0.3 0.3 03 TGA 151.7 LM A 0.3 0.3 0.3 0.00.0 0.0 0 3 TGA 154.9 LM A 0.3 0.3 0.3 0.0 0.0 0.0 0 3 TGA 156.5 LMA 0.3 0.3 0.3 0.0 0.0 0.0 0 3 TGA 160.0 LM A 0.2 0.3 0.3 0.2 0.0 0.0 0.0 0 3 TGA 162.0 LM A 0.2 0.2 0.2 0.00.0 0.0 03 MBO 38.5 LM A 0.9 1.0 1.0 0.0 0.0 0.0 0.9 MDK 0.5 LM A 0.2 0.2 0.2 0.0 0.0 0.0 0 3 MDK 10.7 LM A 0.3 0.3 0.3 0.00.0 0.0 0.3 M DK 20.5 LM A 0.6 0.6 0.6 0.00.0 0.0 0.6 CHI 129.2 LM U 0.4 0.4 0.4 0.0 0.0 0.0 0.0 0.0 0.4 CHI 132.6 LM U 0.4 0.4 0.4 0.4 0.4 0.0 0.0 0.0 0.0 0.0 0.4 CHI 139.4 LM U 0.3 0.3 0.3 0.3 0.00.0 0.0 0.3 "lower' Mackellar Formation Mean: 0 3 9 Standard deviation: 0 3 0 MKR 23.2 MM U 0.3 0.3 0.3 0.0 0.0 0.0 0.0 0.0 0.3 MKR 34.3 MM U 0.4 0.3 0.3 0.0 0.00.0 0.0 0.0 0.3 MKR 42.2 MM U 0.4 0.4 0.4 0.0 0.0 0.0 0.0 0.0 0.3 MMQ 4.3 MM A 0.6 0.6 0.6 0.00.0 0.0 0.6 MMQ 14.0 MM A 0.3 0.4 0.3 0.0 0.0 0.0 0.3 MMQ 26.5 MMA 0.3 0.3 0.3 0.0 0.0 0.0 0.3 MMQ 29.0MM A 0.2 0.2 0.2 0.0 0.0 0.0 0 3 MMQ 33.0 MM A 0.2 0.2 0.2 0.00.0 0.0 0 3 MMA 24.3MM A 0.0 0.0 0.0 0.00.0 0.0 0.0 MMA 38.8 MM A 0.1 0.1 0.1 0.0 0.0 0.0 0.1 MMA 51.0 MM A 0.1 0.1 0.1 0.0 0.0 0.0 0.1 MMA 59.8 MM A 0.1 0.1 0.1 0.0 0.0 0.0 0.1 MMC 37.7 MM A 0.1 0.1 0.1 0.1 0.1 0.00.00.0 0.0 0.1 MMC 49.1 MM A 0.1 0.1 0.1 0.0 0.0 0.0 0.1 MMC 56.7 MM A 0.1 0.1 0.1 0.0 0.0 0.0 0.1 MMC 63.7 MM A 0.1 0.1 0.1 0.0 0.0 0.0 0.1 MMC 64.4 MM A 0.2 0.2 0.2 0.00.0 0.0 03 MMC 71.0 MM A 0.1 0.1 0.1 0.0 0.0 0.0 0.1 MMC 74.8 MM A 0.2 0.2 0.2 0.0 0.0 0.0 0.1 MMC 82.8 MM A 0.2 0.2 0.2 0.0 0.0 0.0 0 3 MMC 87.8 MM A 0.2 0.2 0.2 0.00.0 0.0 03 MMD 7.5 MM U 0.5 0.5 0.5 0.00.0 0.0 0.5 MMD 11.0 MM U 0.4 0.4 0.4 0.00.0 0.0 0.4 MMD 27.0 MM u 0.9 0.9 0.9 0.30.3 0.3 0.6 273

Table 15: (continued).

A venge Sample Altered Total Carbon (9b) Inorganic Carbon (%) Total or Replicate runs Mean Replicate runs M ean Organic Unaltered Carbon (%) TRM 16.5 MM U 0.7 0.7 0.7 0.0 0.0 0.0 0.6 TOM 27.5 MM U 0.4 0.4 0.5 0.5 0.4 0.0 0.0 0.0 0.1 0.0 0.4 TRM 35.1 MM U 0.4 0.5 0.4 0.00.0 0.0 0.4 TOM 47.1 MM U 0.4 0.4 0.4 0.1 0.1 0.1 0.3 CPZ 125.1 MM A 0.2 0.2 0.2 0.00.00.0 0.0 0.0 0.2 CPZ 137.0 MM A 0.2 0.2 0.2 0.0 0.0 0.0 0.0 0.0 0 2 CPZ 145.9 MM A 0.3 0.3 0.3 0.0 0.0 0.0 0.0 0.0 0 3 MTM 223.6 MM U 0.5 0.5 0.5 0.1 0.1 0.1 0.1 0.1 0.4 MTM 232.3 MM U 0.4 0.4 0.4 0.1 0.2 0.1 0.1 0.1 0.3 MTM 246.2 MM U 0.5 0.5 0.5 0.00.0 0.0 0.5 TGA 163.5 MM A 0.2 0.2 0.2 0.00.0 0.0 0.2 TGA 163.6 MM A 0.1 0.1 0.1 0.0 0.0 0.0 0.1 TGA 170.0 MM A 0.1 0.1 0.1 0.00.0 0.0 0.1 TGA 173.0 MM A 0.2 0.2 0.2 0.0 0.0 0.0 0.2 TGA 194.0 MM A 0.1 0.1 0.1 0.1 0.00.0 0.0 0.1 TGF 0.0 MM A 0.0 0.0 0.0 0.00.0 0.0 0.0 TGF 10.0 MM A 0.0 0.0 0.0 0.00.0 0.0 0.0 MBO 54.5 MM U 1.3 1.3 1.3 0.0 0.0 0.0 1.3 MBO 67.8 MM U 1.3 1.3 1.3 0.0 0.0 0.0 1.3 MBO 75.5 MM u 2.0 2.0 2.0 0.0 0.0 0.0 2.0 CHI 153.0 MM u 0.2 0.1 0.2 0.2 0.2 0.0 0.0 0.0 0.2 CHI 169.2 MM A 0.2 0.2 0.2 0.0 0.0 0.0 0 2 CTO 178.5 MM A 0.4 0.4 0.4 0.4 0.4 0.0 0.0 0.0 0.0 0.0 0.4 cm 185.3 MM A 3.0 3.0 3.0 2.82.8 2.8 0.2 cm 192.1 MM A 0.2 0.2 0.2 0.0 0.0 0.0 0 2 MDK 30.8 MM A 0.4 0.4 0.4 0.0 0.1 0.0 0.0 0.4 MDK 40.9 MM A 0.1 0.1 0.1 0.0 0.0 0.0 0.1 MDK 50.1 MM A 0.1 0.1 0.1 0.0 0.0 0.0 0.1 MDK 65.5 MM A 0.1 0.1 0.1 0.00.0 0.0 0.1 MDK 79.0 MM A 0.1 0.1 0.1 0.00.0 0.0 0.1 MDK 91.5 MM A 0.1 0.1 0.1 0.00.00.0 0.0 0.1 "middle" Mackellar Formation Mean: 0.29 Standard deviation: 0.30 MKR 58.5 UM U 0.4 0.3 0.4 0.4 0.4 0.0 0.0 0.0 0.0 0.0 0.3 MMA 73.2 UM A 0.4 0.3 0.3 0.0 0.0 0.0 0.3 MMC 95.2 UM A 0.2 0.3 0.2 0.0 0.0 0.0 0 2 MMC 117.5 UM A 0.3 0.3 0.3 0.0 0.0 0.0 0.3 MMD 62.5 UM U 8.3 8.3 8.3 8.3 8.3 8.1 8.0 8.2 8.2 8.1 0 2 MMD 75.5 UM u 0.4 0.4 0.4 0.00.0 0.0 0.4 274

Table 15: (continued).

Average Sample Altered Total Carbon (%) Inorganic Carbon (%) Total or Replicate nms Mean Replicate runs Mean Organic Unaltered Carbon (%) MMD 106.0 UM U 0.5 0.5 0.5 0.0 0.0 0.0 0.5 MMD 115.5 UM u 0.4 0.4 0.5 0.5 0.4 0.0 0.0 0.0 0.0 0.0 0.4 CPZ 158.1 UM u 0.2 0.2 0.2 0.0 0.0 0.0 0.0 0.0 0 2 CPZ 166.5 UM u 0.2 0.2 0.2 0.0 0.0 0.0 0.0 0.0 0 2 CPZ 176.1 UM u 0.2 0.2 0.2 0.0 0.0 0.0 0.0 0.0 0.1 CPZ 183.4 UM u 0.2 0.2 0.2 0.0 0.0 0.0 0.0 0.0 0 2 CPZ 190.5 UM u 0.2 0.2 0.2 0.0 0.0 0.0 0.0 0.0 0 2 MTM 269.0 UM u 0.4 0.4 0.4 0.4 0.4 0.0 0.0 0.0 0.0 0.0 0.4 MTM 279.1 UM u 0.3 0.3 0.3 0.0 0.0 0.0 0.0 0.0 0 3 MTM 294.2 UM u 0.3 0.3 0.3 0.0 0.0 0.0 0.0 0.0 0.3 TGA 200.3 UM A 0.1 0.1 0.1 0.0 0.0 0.0 0.1 TGA 211.0 UM A 0.1 0.1 0.1 0.0 0.0 0.0 0.1 TGA 213.5 UM A 0.1 0.1 0.1 0.0 0.0 0.0 0.1 TGA 227.5 UM A 0.0 0.0 0.0 0.0 0.0 0.0 0.0 TGA 228.0 UM A 0.1 0.1 0.1 0.0 0.0 0.0 0.1 MBO 88.0 UM U 2.3 2.3 2.3 0.0 0.0 0.0 2.3 MBO 104.0 UM u 1.1 1.0 1.0 1.0 1.0 0.0 0.0 0.0 0.0 1.0 MBO 110.5 UM U 4.8 4.9 4.9 4.9 4.9 4.3 4.2 4.3 4.3 4.3 0.6 MBO 125.0 UM U 1.1 1.1 1.1 0.0 0.0 0.0 1.1 MBO 134.0 UM U 1.3 1.3 1.3 0.0 0.0 0.0 1.3 MDK 119.0 UM A 0.2 0.2 0.2 0.0 0.0 0.0 0 2 "upper" Mackellar Formation Mean: 0.43 Standard deviation: 0.50 ENTIRE MACKELLAR FORMATION: MEAN: 033 STANDARD DEVIATION: 0.36 MKR 90.5 UP A 0.0 0.0 0.0 0.0 0.0 0.0 0.0 TOM 71.6 LF U 0.6 0.6 0.6 0.0 0.0 0.0 0.6 CPZ 201.8 LF u 5.7 5.7 5.8 5.8 5.7 5.5 5.7 5.6 5.6 5.6 0 2 TGF 136.0 LF A 0.4 0.4 0.4 0.0 0.0 0.0 0.4 TGF 138.5 LF A 0.5 0.6 0.5 0.0 0.0 0.0 0.5 "lower" Fairchild Formation Mean: 0.34 Standard deviation: 022 MMA 87.0 UF A 0.9 0.9 0.9 0.9 0.9 0.0 0.0 0.0 o o 0.0 0.9 MBO 170.0 UF U 2.8 2.8 2.8 0.0 0.0 0.0 2.8 MDK 209.0 UF A 0.1 0.1 0.1 0.0 0.0 0.0 0.1 MDK 216.5 UF A 0.1 0.1 0.1 0.0 0.0 0.0 0.1 MDK 229.0 UF A 0.1 0.1 0.1 0.0 0.0 0.0 0.1 275

Table 15: (continued).

A venge Sample Altered Total Carbon (%) Inorganic Carbon (%) Total or Replicate ram Mean Replicate ram Mean Organic Unaltered Carbon <%) "upper” Fairchild Formation Mean: 0.80 Standard deviation: 1.00 ENTIRE FAIRCHILD FORMATION: MEAN: 0.55 STANDARD DEVIATION: 0.75 MMD 270.0 LB U 4.9 4.9 4.9 0.00.0 0.0 4.9 MMD 283.5 LB u 5.5 5.2 5.3 0.0 0.0 0.0 5 3 MMD 295.5 LB u 26.5 26.7 26.6 0.0 0.0 0.0 26.6 MMD 318.5 LB u 40.5 40.5 40.5 0.0 0.0 0.0 40.5 MMD 384.0 LB u 58.0 58.1 58.0 0.0 0.0 0.0 58.0 MMD 417.0 LB u 12.6 12.8 12.7 0.0 0.0 0.0 12.7 MMD 440.5 LB u 13.3 13.3 13.5 13.3 13.3 0.0 0.0 0.0 0.0 0.0 13.3 TGF 218.0 LB u 0.2 0.2 0.2 0.0 0.0 0.0 0.0 0.0 0 2 MPI 28.6 LB A 0.9 1.0 0.9 0.0 0.0 0.0 0.9 MPI 35.8 LB A 6.5 6.4 6.5 0.0 0.0 0.0 6.5 MPI 53.1 LB A 1.6 1.6 1.6 0.0 0.0 0.0 1.6 MPI 54.0 LB A 6.9 6.8 6.8 0.0 0.0 0.0 0.0 6.8 MA6 14.4 LB A 0.1 0.1 0.1 0.0 0.0 0.0 0.1 MA6 45.2 LB A 1.8 1.9 1.8 0.0 0.0 0.0 1.8 MA6 108.2 LB A 29.3 29.7 29.6 29.9 29.6 0.0 0.0 0.0 29.6 MA6 131.2 LB A 14.9 14.9 14.9 0.0 0.0 0.0 14.9 BOB 27.5 LB A 3.9 3.9 3.9 0.0 0.0 0.0 3.9 BOB 89.8 LB A 12.6 12.1 12.4 12.4 12.4 0.0 0.0 0.0 0.0 0.0 114 BOB 116.1 LB A 5.9 5.9 5.9 0.0 0.0 0.0 5.9 "lower" Buckley Formation Mean: 1195 Standard deviation: 15.08 WLG 5.0 UB U 1.4 1.3 1.4 1.4 1.3 0.2 0.2 0.2 0.2 0.2 12 WLG 30.0 UB U 1.1 1.1 1.1 1.1 0.0 0.0 0.0 1.1 WLG 53.0 UB U 1.1 1.1 1.1 1.1 0.0 0.0 0.0 1.1 WLG 58.0 UB u 26.9 27.3 27.2 27.1 0.0 0.0 0.0 27.1 MPU 40.4 UB A 0.8 0.8 0.8 0.0 0.0 0.0 0.8 MFU 52.8 UB A 2.2 2.3 2.3 0.0 0.0 0.0 2.3 MPU 117.3 UB A 3.3 3.3 3.3 0.0 0.0 0.0 3.3 MPU 159.4 UB U 29.7 30.2 30.0 0.0 0.0 0.0 30.0 MPU 183.8 UB U 37.7 37.8 37.7 0.0 0.0 0.0 37.7 MPU 214.3 UB A 2.8 2.8 2.8 0.0 0.0 0.0 2.8 MPU 222.9 UB A 9.2 9.2 9.2 0.0 0.0 0.0 9 2 MPU 241.5 UB A 1.2 1.2 1.2 1.2 1.2 0.0 0.0 0.0 0.0 0.0 12 276 Table 15: (continued).

Avenge Sample Altered Total Carbon (5&) Inorganic Carbon (%) Total or Replicate tuns Mean Replicate tuns Mean Organic Unaltered Carbon (%) M TR 13.1 UBA 3.5 3.6 3.6 0.0 0.0 0.0 3.6 M TR 61.1 UB A 6.9 7.0 6.9 0.0 0.0 0.0 6.9 MIR 121.7UB A 29.3 29.7 29.5 0.0 0.0 0.0 29.5 M TR 130.5 UBA 5.3 5.2 5.2 0.0 0.0 0.0 5 2 MTR 185.9UB A 9.5 9.5 9.5 0.00.0 0.0 9.5 MIR 203.7 UB A 22.1 21.9 22.0 0.0 0.0 0.0 22.0 MAS 33.2 UB A 0.1 0.1 0.1 0.0 0.0 0.0 0.1 MAS 51.7 UB A 0.20.2 0.2 0.0 0.0 0.0 0.2 MA5 95.8 UB A 0.8 0.8 0.8 0.00.0 0.0 0.8 MAS 109.6UB A 3.7 3.6 3.7 0.0 0.0 0.0 0.0 3.6 MA5 114.1 UBA 1.0 1.0 1.0 0.0 0.0 0.0 1.0 MA5 152.0 UB A 1.0 1.0 1.0 0.0 0.0 0.0 1.0 M A4 9.2 UB A 1.8 1.8 1.8 0.0 0.0 0.0 1.8 MA4 16.0 UBA 19.0 17.9 19.0 18.6 18.6 0.0 0.0 0.0 0.0 0.0 18.6 M A4 37.0 UB A 1.0 1.0 1.0 0.0 0.0 0.0 0.0 1.0 LPP 28.0 UB A 0.7 0.6 0.6 0.00.0 0.0 0.6 LPP 39.5 UB U 0.4 0.4 0.4 0.0 0.0 0.0 0.4 LPP 54.5 UB U 0.2 0.2 0.2 0.2 0.2 0.0 0.0 0.0 0.0 0.0 0.2 LPP 58.5 UB U 50.5 52.3 51.4 0.0 0.0 0.0 51.4 "upper" Buckley Formation Mean: 8.88 Standard deviation: 13.04 ENTIRE BUCKT ,FY FORMATION: MEAN: 10.42 STANDARD DEVIATION: 13.99 APPENDIX B

INORGANIC GEOCHEMICAL DATA

BEARDMORE GLACIER REGION, ANTARCTICA

277 278

Appendix B contains the results of inorganic geochemical analysis of Permian mudrocks from the Beardmore Glacier region, Antarctica. The first section includes a discussion of the reproducibility of the data, and a table that shows the results of replicate analyses for ten of the samples. This is followed by a table that contains the complete raw results of inorganic geochemical analyses. The remaining seven sections contain supplemental graphs that illustrate the important elemental associations discussed in the text of Chapter IV. These graphs demonstrate the following relationships:

* * The relationship between vitrinite reflectance and the abundance of

representative elements.

- The relationship between the abundances of representative elements and

proximity to intrusive bodies.

* * The relationship between the abundances of representative elementals and

organic carbon content.

■ The relationship between the abundances of transition metals and organic

carbon content, with special analysis of the Buckley Formation.

* * The relationship between the abundances of representative elements and

normalized Si02 content.

* * The relationship between the abundances of representative elementals and

normalized A1203 content.

* * The relationship between the abundances of representative elements and

normalized Fe203 content. 279

Precision, accuracy and reproducibility of inorganic geochemical analyses

Precision, accuracy and reproducibility data from major, minor and rare earth element chemical analyses are summarized in this part of Appendix B.

Precision and accuracy data are supplied by XRAL laboratories, Ontario, Canada.

Reproducibility data were calculated by submitting replicate samples under fictitious labels.

Precision, accuracy and reoroduciblitv using XRF

XRAL Laboratories monitors the precision and accuracy of their wavelength dispersive XRF analyses using internal and external controls. Instrument stability is measured by running a sample ten times and calculating a coefficient of variation using the following formula: Coefficient of variation (V) = [standard deviation (a)

/ mean (x) ] x 100. The coefficient of variation puts results on a percentage basis, and allows comparison of the reproducibility of different elements. Coefficients of variation calculated from instrument stability tests are less than 5% of the mean for all elements analyzed by XRF (XRAL in-house report for clients). A test of sample preparation (42 replicate analyses) by XRAL Laboratories yields coefficients of variation less than 3.6% for all elements analyzed by XRF. This is closer to a measure of actual analytical conditions, but does not exclude the possibility that matrix corrections have created a systematic error that affects the accuracy of the analyses. 280 External checks of the accuracy of XRF analysis are performed by running

internationally recognized reference materials that have previously established

elemental abundances. Element concentrations in these standard samples are

determined by a variety of analytical methods, thus reducing systematic errors that

are inherent in some processes. Most reference samples run by XRAL Laboratories

yield highly accurate and reproducible results, with coefficients of variation that

differ from established values by less than 5% of the mean for Si, Al, Ca, K and P.

Mg and Fe are slightly less reproducible, with coefficients of variation equal to

7.5% and 5.8%, respectively. Mn and Ti are the least reproducible elements analyzed by XRF, with coefficients of variation equal to 12.6% and 25.2% respectively. The large error in reproducibility of Ti values is due to low Ti abundances in the standard samples. Percent error is greatest near the lower detection limit of an element, and decreases with increasing elemental abundance.

Internal tests of reproducibility were also conducted in this study, with every tenth sample submitted in duplicate under a fictitious label. One sample (MTM

269.0) was submitted five times under different labels to provide a more accurate statistical test of reproducibility. This is a "worst-case" test of reproducibility, since samples and replicates were submitted separately over a period of three years.

Results of these replicate runs are shown in Table 4a. Most XRF data are highly reproducible, with mean coefficients of variation less than 5% for Si, Al, K, P, Fe,

Mg and Ti. Ca and Na are less reproducible, with coefficients of variation of

13.9% and 12.3%, respectively. 281 Precision, accuracy and reproducibiltv using DCP

XRAL laboratories does not report instrument stability, sample preparation reproducibility or reference standard reproducibility tests for DCP analysis. Tests of reproducibility using blind replicate samples from this study give an indication of the reproducibility of the laboratory procedures, although this does not represent the true

accuracy of the method. A potential problem with DCP analysis is sample preparation, which relies on the assumption that all elemental constituents are taken into solution

by the acid baths. Error is introduced to DCP analysis if samples are partially digested, resulting in apparent elemental abundances that are lower than the true concentrations. Coefficients of variation calculated from replicate runs (Table 4a) give proportional deviations that lie between 7.9% and 10.8% of the mean for Be, B, V, Ni,

Cu, Zn and Pb. These deviations are moderately high, and may indicate incomplete

sample digestion for some minor elements analyzed by DCP. Ge is the only element with a relatively low coefficient of variation (3.3%), and Ag and Cd are essentially invariant in this sample group.

Precision, accuracy and reproducibility using INAA

XRAL Laboratories uses internal and external monitoring to check the precision and accuracy of INAA data. Instrument stability (precision) is tested by running a standard sample ten times and analyzing the results of the analyses (XRAL

Laboratories in-house report for clients). Coefficients of variability calculated from these replicate runs indicates that INAA results are reproducible to within 5% of the 282 stated mean for Br, Co, Cr, Cs, Fe, Hf, Sc, Th, La, Ce, Sm, and Lu. Results are slightly less reproducible for Nd, Eu, Tb, and Yb, with coefficients of variation that lie between 5% and 10% of the mean. Mo and Se have poor reproducibility in this analysis of precision, with coefficients of variation equal to 60.0% and 14.8%, respectively. Au, As, Sb, Ta, W, Ir and U are not listed in the discussion of precision.

Accuracy of INAA data is tested by running internationally recognized reference standards and comparing XRAL’s results to the accepted values. This provides an external check of INAA analysis, although until recently INAA was the only precise method for quantifying rare earth element abundances (Potts, 1987).

Values measured by XRAL differ from the accepted value by less than 5% for As, Co,

Cr, Br, Sc, Mo, Sb, Cs, La, and Ce. This group of elements has accurate and reproducible minor and trace element concentrations. The coefficient of variation lies between 5% and 10% for Hf, Se, Nd, Sm, Yb, Lu and U, indicating some problems with accuracy, but generally acceptable results. Coefficients of variability exceed 10% of the mean for Th (11.1% V), W (18.4% V), Eu (10.8% V) and Tb (13.2% V).

Analyses of the latter group of elements is not acceptable when compared to standard values. Accepted standard values are not available for comparable comparison of the accuracy of Au, Ta and Ir analysis.

Reproducibility of INAA data for the Beardmore samples is tested by submitting an unmarked duplicate of every tenth sample. One sample (MTM 269.0) was submitted five times to provide an accurate statistical measure of reproducibility.

Results of these replicate runs are presented in Table 4a. W, La, Sm, and Yb are 283 highly reproducible, with coefficients of variation less than 5% of the mean for replicate samples. Sc, Cr, Sb, Cs, Hf, Pb, Th, U, Ce, Nd, Tb and Lu are less reproducible, with coefficients of variation that lie between 5% and 10% of the mean.

Co, As, Br and Eu are least reproducible, with coefficients of variability that exceed

10%. Reproducibility numbers are not available for Au, Se, Mo, Ta and Ir because these elements do not exceed the lower limit of detection for INAA. 284 Table 16: Data from replicate analysis of precision, accuracy and reproducibility for major, minor and rare earth elements. Sample ID follows the convention established in Figure 6.

SamplelD Si02 A1203 CaO Na20 K20 P205 Fe203 MgO Mn D 0 2 Units of measurement % % %% % % % % (ppm) (ppm) Method of Analysis XRFXRFXRFXRF XRFXRF XRF XRF XRF XRF Method Detection Level 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 M IM 129.0LP 67.8 14.6 0.74 1.38 3.41 0.17 4.87 2.59 380 0.68 MTM129.0LP, rcp.l 62.8 16.3 1.02 1.47 3.85 0.17 5.90 3.22 800 0.78 Mean: 65.3 15.5 0.9 1.4 3.6 0 2 5.4 2.9 590.0 0.7 Standard deviation: 2.5 0.8 0.1 0.0 0 2 0.0 0.5 0.3 210.0 0.0 Coefficient of variation: 3.8 5.5 15.9 32 6.1 0.0 9.6 10.8 35.6 6.8 MKR6.0LM 59.3 17.7 0.50 1.17 3.78 0.16 7.20 3.54 370 0.78 MKR6.0LM, rep. 1 59.3 16.7 0.50 1.44 3.71 0.18 6.95 3.57 600 0.74 Mean: 59.3 17.2 0.5 1.3 3.7 0 2 7.1 3.6 485.0 0.8 Standard deviation: 0.0 0.5 0.0 0.1 0.0 0.0 0.1 0.0 115.0 0.0 Coefficient of variation: 0.0 2.9 0.0 10.3 0.9 5.9 1.8 0.4 23.7 2.4 CHU32.6LM 56.8 18.6 0.04 0.89 4.20 0.18 8.77 3.63 1000 0.84 CHU32.6LM.iep. 1 57.1 18.3 0.44 1.07 4.12 0.20 9.02 3.72 1000 0.84 Mean: 57.0 18.5 0 2 1.0 4 2 0 2 8.9 3.7 1000.0 0.8 Standard deviation: 0.1 0.1 0.2 0.1 0.0 0.0 0.1 0.0 0.0 0.0 Coefficient of variation: 0.3 0.8 83.3 9 2 1.0 5.3 1.4 1 2 0.0 0.1 TRM27.5MM 61.7 17.0 0.44 1.05 3.51 0.19 7.20 3.24 400 0.77 TRM27.5MM, rep. 1 61.0 16.7 0.43 1.28 3.53 0.20 7.31 3.31 700 0.76 Mean: 61.4 16.9 0.4 12 3.5 0 2 7.3 3.3 550.0 0.8 Standard deviation: 0.3 0.1 0.0 0.1 0.0 0.0 0.1 0.0 150.0 0.0 Coefficient of variation: 0.6 0.9 1.1 9.9 0.3 2.6 0.8 1.1 27.3 0.5 MTM269.0UM 58.0 19.1 0.22 0.62 4.38 0.14 8.02 3.43 490 0.84 MTM269.0UM, rep. 1 59.2 18.2 0.27 0.92 4.07 0.16 8.22 3.50 800 0.85 MTM269.0UM, rep. 2 58.2 18.7 0.25 0.91 4.27 0.15 8.21 3.52 800 0.82 MTM269.0UM, rep. 3 58.4 18.4 0.25 0.89 4.18 0.15 8.21 3.53 800 0.83 MTM269.0UM, rep. 4 58.0 18.7 0.27 0.88 4.25 0.16 8.44 3.58 800 0.89 Mean: 58.4 18.6 0.3 0.8 4.2 0 2 8.2 3.5 738.0 0.8 Standard deviation: 0.4 0.3 0.0 0.1 0.1 0.0 0.1 0.0 124.0 0.0 Coefficient of variation: 0.8 1.6 7.3 13.4 2.4 4.9 1.6 1.4 16.8 2.8 MMD115.5UM 53.6 20.0 0.25 0.68 4.70 0.12 9.23 4.06 700 0.72 MMD115.5UM, rep. 1 56.1 18.6 0.32 0.96 4.37 0.13 8.88 3.73 700 0.75 Mean: 54.9 19.3 0.3 0.8 4.5 0.1 9.1 3.9 700.0 0.7 Standard deviation: 12 0.7 0.0 0.1 0 2 0.0 0 2 0 2 0.0 0.0 Coefficient of variation: 2.3 3.6 12.3 17.1 3.6 4.0 1.9 4 2 0.0 1.9 MMD440.5LB 48.0 20.5 0.74 0.44 2.34 0.06 3.07 1.69 160 0.90 MMD440.5LB, rep. 1 49.9 20.9 0.65 0.63 2.30 0.06 3.16 1.93 300 0.96 Mean: 49.0 20.7 0.7 0.5 2.3 0.1 3.1 1.8 230.0 0.9 Standard deviation: 0.9 0 2 0.0 0.1 0.0 0.0 0.0 0.1 70.0 0.0 Coefficient of variation: 1.9 1.0 6.5 17.8 0.9 0.0 1.4 6.6 30.4 3.1 285 Table 16: continued.

SamplelD Si02 A1203 CaO N a20 K20 I ! M n T i02 Units of measurement % % % « % % % % (ppm) (ppm) Method of Analysis XRF XRFXRF XRF XRF XRF XRF XRF XRF XRF Method Detection Level 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 MPU241.5UB 66.8 17.9 1.06 2.01 3.36 0.13 1.05 0.79 72 0.88 MPU241.5UB, rep. 1 66.4 16.8 1.13 2.40 3.08 0.14 0.92 0.80 200 0.72 Mean: 66.6 17.4 1.1 2 2 3.2 0.1 1.0 0.8 136.0 0.8 Standard deviation: 0.2 0.5 0.0 0 2 0.1 0.0 0.1 0.0 64.0 0.1 Coefficient of variation: 0.3 3 2 3 2 8.8 4.3 3.7 6.6 0.6 47.1 9.9 MA5152.0UB 70.8 16.2 0.38 1.96 2.55 0.06 0.82 0.82 92 0.47 MAR152.0UB, rep. 1 69.5 16.3 0.42 2.32 2.59 0.06 0.81 0.87 200 0.49 Mean: 70.2 16.3 0.4 2.1 2.6 0.1 0.8 0.8 146.0 0.5 Standard deviation: 0.6 0.0 0.0 0 2 0.0 0.0 0.0 0.0 54.0 0.0 Coefficient of variation: 0.9 0.3 5.0 8.4 0.8 0.0 0.6 3.0 37.0 1.6 LPP54.5UB 60.7 23.4 0.71 0.44 6.52 0.17 0.79 0.63 420 0.92 LPP54.5UB, rep. 1 60.3 22.8 0.78 0.73 6.51 0.18 0.80 0.69 200 0.93 Mean: 60.5 23.1 0.7 0.6 6.5 0.2 0.8 0.7 310.0 0.9 Standard deviation: 0 2 0.3 0.0 0.1 0.0 0.0 0.0 0.0 110.0 0.0 Coefficient of variation: 0.3 1.3 4.7 24.8 0.1 2.9 0.6 4.5 35.5 0.7 Mean coefficient of variation 1.1 2.1 13.9 12.3 2.0 2.9 2.6 3.4 25.3 3.0 286 Table 16: continued.

Sam pklD Au Be B Sc V Cr Co Ni Cu Units of measurement (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) Method of Analysis INAA DCP DCP INAADCP INAA INAA DCPDCP Method Detection Level 5 or 10 1 10 0.1 2 2 1 1 0.5 MTM129.0LP 10 5 70 12.8 100 78 12 33 23.0 MTM129.0LP, rep.l 20 5 71 14.7 105 94 14 42 39.6 Mean: 15.0 5.0 70.5 13.8 102.5 86.0 13.0 37.5 31.3 Standard deviation: 5.0 0.0 0.5 1.0 2.5 8.0 1.0 4.5 8.3 Coefficient of variation: 33.3 0.0 0.7 6.9 2.4 9.3 7.7 12.0 26.5 MKR6.0LM 10 6 90 18.1 150 120 18 52 36.0 MKR6.0LM, rep. 1 5 5 87 16.2 108 100 17 50 36.6 Mean: n/a 5.5 88.5 17.2 129.0 110.0 17.5 51.0 36.3 Standard deviation: n/a 0.5 1.5 0.9 21.0 10.0 0.5 1.0 0.3 Coefficient of variation: n/a 9.1 1.7 5.5 16.3 9.1 2.9 2.0 0.8 CHU32.6LM 5 6 40 18.0 140 110 20 74 62.0 CHU32.6LM.rep. 1 5 5 36 17.6 no 120 25 65 53.8 Mean: n/a 5.5 38.0 17.8 125.0 115.0 22.5 69.5 57.9 Standard deviation: n/a 0.5 2.0 0.2 15.0 5.0 2.5 4.5 4.1 Coefficient of variation: n/a 9.1 5.3 1.1 12.0 4.3 11.1 6.5 7.1 TRM27.5MM 10 6 80 16.2 140 110 14 45 28.0 TRM27.5MM, rep. 1 5 4 79 15.9 94 110 16 53 34.2 Mean: n/a 5.0 79.5 16.1 117.0 110.0 15.0 49.0 31.1 Standard deviation: n/a 1.0 0.5 0.1 23.0 0.0 1.0 4.0 3.1 Coefficient of variation: n/a 20.0 0.6 0.9 19.7 0.0 6.7 8.2 10.0 MTM269.0UM 10 7 50 19.8 150 140 22 62 45.0 MTM269.0UM, rep. 1 5 5 57 16.3 115 120 24 69 48.1 MTM269.0UM, rep. 2 5 7 58 17.0 145 120 25 73 45.8 MTM269.0UM, rep, 3 5 7 61 16.3 150 100 23 65 46.2 MTM269.0UM, rep. 4 5 8 67 16.9 154 120 18 62 49.7 Mean: n/a 6.8 58.6 17.3 142.8 120.0 22.4 66.2 47.0 Standard deviation: n/a 1.0 5.5 1.3 14.2 12.6 2.4 4.3 1.7 Coefficient of variation: n/a 14.4 9.4 7.6 9.9 10.5 10.8 6.4 3.6 MMD115.5UM 5 6 60 20.7 150 130 18 79 54.0 MMD115.5UM,rep. 1 5 6 52 18.4 124 120 17 59 48.0 Mean: n/a 6.0 56.0 19.6 137.0 125.0 17.5 69.0 51.0 Standard deviation: n/a 0.0 4.0 1.1 13.0 5.0 0.5 10.0 3.0 Coefficient of variation: n/a 0.0 7.1 5.9 9.5 4.0 2.9 14.5 5.9 MMD440.5LB 5 5 30 15.3 100 140 10 60 79.0 MMD440.5LB, rep. 1 5 5 33 13.2 112 130 11 69 91.1 Mean: n/a 5.0 31.5 14.3 106.0 135.0 10.5 64.5 85.1 Standard deviation: n/a 0.0 1.5 1.1 6.0 5.0 0.5 4.5 6.1 Coefficient of variation: n/a 0.0 4.8 7.4 5.7 3.7 4.8 7.0 7.1 287

Table 16: continued.

Sam pklD Au Be B Sc V Cr Co Ni Cu U nits o f measurement (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (Ppm) (ppm) (ppm) Method of Analysis INAA DCP DCP INAADCP INAAINAA DCP DCP Method Detection Level 5 or 10 I 10 0.1 2 2 1 1 0 3 MPU241.5UB 10 3 30 10.7 110 29 8 10 27.0 MPU241.5UB, rep. 1 6 3 49 8.2 102 22 12 21 38.2 Mean: n/a 3.0 39.5 9.5 106.0 25.5 10.0 15.5 32.6 Standard deviation: n/a 0.0 9.5 1 2 4.0 3.5 2.0 5.5 5.6 Coefficient of variation: n/a 0.0 24.1 13.2 3.8 13.7 20.0 35.5 17.2 M A5I52.0UB 10 2 30 8.6 30 17 3 6 7.0 MAR152.0UB, rep. 1 5 4 24 7.7 22 9 4 6 8.8 Mean: n/a 3.0 27.0 8.2 26.0 13.0 3.5 6.0 7.9 Standard deviation: n/a 1.0 3.0 0.4 4.0 4.0 0.5 0.0 0.9 Coefficient of variation: n/a 33.3 11.1 5.5 15.4 30.8 14.3 0.0 11.4 LPP54.5UB 10 4 20 13.3 59 15 12 8 22.0 LPP54.5UB, rep. 1 6 4 34 11.6 54 13 5 8 24.1 Mean: n/a 4.0 27.0 12.5 56.5 14.0 8.5 8.0 23.1 Standard deviation: n/a 0.0 7.0 0.8 2.5 1.0 3.5 0.0 1.1 Coefficient of variation: n/a 0.0 25.9 6.8 4.4 7.1 41.2 0.0 4.6 Mean coefficient of variation n/a 8.6 9.1 6.1 9.9 9.3 12.2 9.2 9.4 288 Table 16: continued.

SamplelD Zn Ge As Se Br Mo Ag Cd Units of measurement (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) Method of Analysis DCP DCP INAA INAA INAA INAA DCPDCP Method Detection Level 0.5 10 2 3 1 5 0.5 1 MTM129.0LP 81.0 10 4 3 2 5 0.5 1 MTM129.0LP, rep.l 101.0 10 4 3 2 5 0.5 1 Mean: 91.0 n/a 4.0 n/a 2.0 n/a n/a n/a Standard deviation: 10.0 n/a 0.0 n/a 0.0 n/a n/a n/a Coefficient of variation: 11.0 n/a 0.0 n/a 0.0 n/a n/a n/a MKR6.0LM 120.0 10 2 3 2 5 0.5 1 MKR6.0LM, rep. 1 128.0 10 2 3 2 5 0.5 1 Mean: 124.0 n/a n/a n/a 2.0 n/a n/a n/a Standard deviation: 4.0 n/a n/a n/a 0.0 n/a n/a n/a Coefficient of variation: 3.2 n/a n/a n/a 0.0 n/a n/a n/a CHU32.6LM 130.0 10 6 3 1 5 0.5 1 CHU32.6LM, iep. 1 149.0 10 6 3 3 5 0.5 1 Mean: 139.5 n/a 6.0 n/a 2.0 n/a n/a n/a Standard deviation: 9.5 n/a 0.0 n/a 1.0 n/a n/a n/a Coefficient of variation: 6.8 n/a 0.0 n/a 50.0 n/a n/a n/a TRM27.5MM 100.0 20 2 3 2 5 0.5 1 'ntM27.5MM.rep. 1 134.0 10 3 3 3 5 0.5 1 Mean: 117.0 15.0 2.5 n/a 2.5 n/a n/a n/a Standard deviation: 17.0 5.0 0.5 n/a 0.5 n/a n/a n/a Coefficient of variation: 14.5 33.3 20.0 n/a 20.0 n/a n/a n/a MTM269.0UM 130.0 10 2 3 2 5 0.5 1 MTM269.0UM, rep. 1 150.0 10 4 3 3 5 0.5 1 MTM269.0UM, rep. 2 152.0 10 2 3 2 5 0.5 1 MTM269.0UM, rep. 3 150.0 10 2 3 2 5 0.5 1 MTM269.0UM, rep. 4 155.0 10 2 3 2 5 0.5 1 Mean: 147.4 n/a 2.4 n/a 2.2 n/a n/a n/a Standard deviation: 8.9 n/a 0.8 n/a 0.4 n/a n/a n/a Coefficient of variation: 6.0 n/a 33.3 n/a 18.2 n/a n/a n/a MMD115.5UM 140.0 10 4 3 1 5 0.5 1 MMD115.5UM, rep. 1 139.0 10 2 3 3 5 0.5 1 Mean: 139.5 n/a 3.0 n/a 2.0 n/a n/a n/a Standard deviation: 0.5 n/a 1.0 n/a 1.0 n/a n/a n/a Coefficient of variation: 0.4 n/a 33.3 n/a 50.0 n/a n/a n/a MMD440.5LB 77.0 10 2 3 4 5 0.5 1 MMD440.5LB, rep. 1 95.7 10 2 3 7 5 0.5 1 Mean: 86.4 n/a n/a n/a 5.5 n/a n/a n/a Standard deviation: 9.3 n/a n/a n/a 1.5 n/a n/a n/a Coefficient o f variation: 10.8 n/a n/a n/a 27.3 n/a n/a n/a 289 Table 16: continued.

SamplelD Zo Ge As Se Br Mo Ag Cd Units of measurement (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) ft>pm) (ppm) Method of Analysis DCP DCP INAA INAA INAA INAADCP DCP Method Detection Level 0.5 10 2 3 1 5 0.5 1 MPU241.5UB 55.0 10 7 3 4 5 0.5 1 MPU241.5UB, rep. 1 76.3 10 27 3 5 5 0.5 1 Mean: 65.7 n/a 17.0 n/a 4.5 n/a n/a n/a Standard deviation: 10.6 n/a 10.0 n/a 0.5 n/a n/a n/a Coefficient of variation: 16.2 n/a 58.8 n/a 11.1 n/a n/a n/a MA5152.0UB 84.0 10 2 3 3 5 0.5 1 MARlS2.0UB.rep. 1 94.3 10 2 3 4 5 0.5 1 Mean: 89.2 n/a n/a n/a 3.5 n/a n/a n/a Standard deviation: 5.1 n/a n/a n/a 0.5 n/a n/a n/a Coefficient of variation: 5.8 n/a n/a n/a 14.3 n/a n/a n/a LPP54.5UB 66.0 10 18 3 3 5 0.5 1 LPP54.5UB, rep. 1 72.2 10 16 3 3 5 0.5 1 Mean: 69.1 n/a 17.0 n/a 3.0 n/a n/a n/a Standard deviation: 3.1 n/a 1.0 n/a 0.0 n/a n/a n/a Coefficient of variation: 4.5 n/a 5.9 n/a 0.0 n/a n/a n/a Mean coefficient of variation 7.9 3.3 15.1 0.0 19.1 n/a n/a n/a 290 Table 16: continued.

Sam plelD Sb Cs H f Ta W Ir Pb H i U Units of measurement (ppm) (PI*n) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) Method of Analysis INAA INAA INAAINAAINAAINAA DCP INAAINAA Method Detection Level 0 2 0.5 1 1 3 20 2 0.5 0.5 MTM 129.0LP 0.3 6.4 8.0 1 3 20 20 14.0 2.8 MTM129.0LP, iep.1 0.5 9.0 6.2 1 3 20 18 18.0 3.6 M ean: 0.4 7.7 7.1 n/a 3.0 n/a 19.0 16.0 3 2 Standard deviation: 0.1 1.3 0.9 n/a 0.0 n/a 1.0 2.0 0.4 Coefficient of variation: 25.0 16.9 12.7 n/a 0.0 n/a 5.3 12.5 12.5 MKR6.0LM 0.4 10.5 5.0 1 3 20 22 16.0 3.8 MKR6.0LM, rep. 1 0.4 9.0 4.5 1 3 20 19 15.0 3.2 Mean: 0.4 9.8 4.8 n/a 3.0 n/a 20.5 15.5 3.5 Standard deviation: 0.0 0.8 0 2 n/a 0.0 n/a 1.5 0.5 0.3 Coefficient of variation: 0.0 7.7 5.3 n/a 0.0 n/a 7.3 3 2 8.6 CHU32.6LM 0.6 15.7 3.0 I 3 20 32 24.0 6.5 CHU32.6LM, rep. 1 0.6 12.0 3.1 1 3 20 25 25.0 6.0 M ean: 0.6 13.9 3.1 n/a 3.0 n/a 28.5 24.5 6.3 Standard deviation: 0.0 1.9 0.0 n/a 0.0 n/a 3.5 0.5 0 2 Coefficient of variation: 0.0 13.4 1.6 n/a 0.0 n/a 12.3 2.0 4.0 TRM27.5MM 0.4 8.0 6.0 1 3 20 16 16.0 3.7 TRM27.5MM, rep. 1 0.5 8.0 6.0 1 3 20 21 18.0 3.6 M ean: 0.5 8.0 6.0 n/a 3.0 n/a 18.5 17.0 3.7 Standard deviation: 0.1 0.0 0.0 n/a 0.0 n/a 2.5 1.0 0.0 Coefficient of variation: 11.1 0.0 0.0 n/a 0.0 n/a 13.5 5.9 1.4 MTM269.0UM 0.7 11.2 5.0 1 4 20 20 21.0 5.2 MTM269.0UM, rep. 1 0.6 11.0 4.4 1 3 20 31 22.0 4.9 MTM269.0UM, rep. 2 0.6 10.0 3.5 1 3 20 23 20.0 4.0 MTM269.0UM, rep. 3 0.6 9.0 3.9 1 3 20 30 21.0 4.3 MTM269.0UM, rep. 4 0.6 11.0 3.6 1 3 20 28 22.0 5.1 M ean: 0.6 10.4 4.1 n/a 3.2 n/a 26.4 21.2 4.7 Standard deviation: 0.0 0.8 0.6 n/a 0.4 n/a 4.2 0.7 0.5 Coefficient of variation: 6.5 8.0 13.6 n/a 12.5 n/a 16.0 3.5 10.0 MMD115.SUM 0.5 14.6 4,0 1 3 20 26 17.0 3.7 MMD115.5UM, rep. 1 0.5 9.0 3.4 1 3 20 22 20.0 3.4 Mean: 0.5 11.8 3.7 n/a 3.0 n/a 24.0 18.5 3.6 Standard deviation: 0.0 2.8 0.3 n/a 0.0 n/a 2.0 1.5 0.1 Coefficient of variation: 0.0 23.7 8.1 n/a 0.0 n/a 8.3 8.1 4 2 MMD440.5LB 0.2 6.8 3.0 1 4 20 22 28.0 7.3 MMD440.5LB, rep. 1 0.2 7.0 2.6 1 3 20 27 23.0 5.8 M ean: 0 5 6.9 2.8 n/a 3.5 n/a 24.5 25.5 6.6 Standard deviation: 0.0 0.1 0.2 n/a 0.5 n/a 2.5 2.5 0.7 Coefficient of variation: 0.0 1.4 7.1 n/a 14.3 n/a 10.2 9.8 11.5 291 Table 16: continued.

SamplelD Sb Cs Hf Ta W Ir Pb Th U Units o f measurement (ppm) (ppn) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) Method of Analysis INAAINAA INAAINAAINAAINAA DCP INAA INAA Method Detection Level 0.2 0.5 1 1 3 20 2 0.5 0.5 MPU241.5UB 0.6 6.6 6.0 1 3 20 16 11.0 4.1 MFU241.5UB, rep. 1 0.5 9.0 4.9 1 3 20 18 12.0 3.3 Mean: 0.6 7.8 5.5 n/a 3.0 n/a 17.0 11.5 3.7 Standard deviation: 0.0 12 0.6 n/a 0.0 n/a 1.0 0.5 0.4 Coefficient of variation: 9.1 15.4 10.1 n/a 0.0 n/a 5.9 4.3 10.8 MA5152.0UB 0.3 8.3 8.0 1 3 20 22 14.0 3.9 MAR152.0UB, rep. 1 0.4 8.0 6.2 1 3 20 23 13.0 3.7 Mean: 0.4 8 2 7.1 n/a 3.0 n/a 22.5 13.5 3.8 Standard deviation: 0.0 0 2 0.9 n/a 0.0 n/a 0.5 0.5 0.1 Coefficient of variation: 14.3 1.8 12.7 n/a 0.0 n/a 2.2 3.7 2.6 LPP54.5UB 0.7 9.8 14.0 1 3 20 26 19.0 4.5 LPP54.5UB, rep. 1 0.7 9.0 10.0 1 4 20 28 18.0 4.0 Mean: 0.7 9.4 12.0 n/a 3.5 n/a 27.0 18.5 4.3 Standard deviation-. 0.0 0.4 2.0 n/a 0.5 n/a 1.0 0.5 0 2 Coefficient of variation: 0.0 4.3 16.7 n/a 14.3 n/a 3.7 2.7 5.9 Mean coefficient of variation 6.6 9.3 8.8 n/a 4.1 n/a 8.5 5.6 7.1 292

Table 16: continued.

SamplelD La Ce Nd Sm Go Tb Yb Lu Units of measurement (ppm) (ppm) to rn ) (ppm) (ppm) (ppm) (ppm) (ppm) Method of Analysis INAA INAAINAAINAAINAA INAAINAAINAA Method Detection Level 0.5 3 5 0.1 0 2 0.5 0.2 0.05 M IM 129.0LP 52.9 107 42 6.9 1.3 0.8 3.0 0.47 MTM129.0LP, rep.l 49.6 98 38 6.7 1.2 0.9 3.2 0.50 Mean: 51.3 102.5 40.0 6.8 1.3 0.9 3.1 0.5 Standard deviation: 1.6 4.5 2.0 0.1 0.0 0.0 0.1 0.0 Coefficient of variation: 3 2 4.4 5.0 1.5 4.0 5.9 3 2 3.1 MKR6.0LM 60.0 115 48 7.4 1.4 1.1 3.0 0.48 MKR6.0LM, rep. 1 60.5 117 48 8.8 2.0 1.2 2.9 0.49 Mean: 60.3 116.0 48.0 8.1 1.7 12 3.0 0.5 Standard deviation: 0.2 1.0 0.0 0.7 0.3 0.0 0.0 0.0 Coefficient of variation: 0.4 0.9 0.0 8.6 17.6 4.3 1.7 1.0 CHI132.6LM 72.9 119 42 8.3 0.8 1.3 3.0 0.56 CHU32.6LM, rep. 1 65.6 124 48 8.3 1.6 1.2 3.1 0.43 Mean: 69.3 121.5 45.0 8.3 12 1.3 3.1 0.5 Standard deviation: 3.7 2.5 3.0 0.0 0.4 0.0 0.0 0.1 Coefficient of variation: 5.3 2.1 6.7 0.0 33.3 4.0 1.6 13.1 TRM27.5MM 55.7 106 44 7.0 1.7 1.4 3.2 0.50 TRM27.5MM, rep. 1 56.8 108 44 7.9 1.6 1.0 3.7 0.55 Mean: 56.3 107.0 44.0 7.5 1.7 1.2 3.5 0.5 Standard deviation: 0.5 1.0 0.0 0.5 0.0 0 2 0.3 0.0 Coefficient of variation: 1.0 0.9 0.0 6.0 3.0 16.7 7 2 4.8 MTM269.0UM 60.7 119 49 7.2 1.4 1.1 3.3 0.51 MTM269.0UM, rep. 1 64.7 127 50 8.6 1.5 0.8 3.2 0.49 MTM269.0UM, rep. 2 54.3 102 39 6.8 1.2 0.8 3.1 0.46 MTM269.0UM, rep. 3 57.1 111 43 7.6 1.1 0.7 2.9 0.44 MTM269.0UM, rep. 4 62.4 119 46 8.0 1.2 0.8 3.1 0.47 Mean: 59.8 115.6 45.4 7.6 1.3 0.8 3.1 0.5 Standard deviation: 3.7 8.5 4.0 0.6 0.1 0.1 0.1 0.0 Coefficient of variation: 6 2 7.3 8.9 8 2 11.5 16.1 4.3 5.1 MMD115.5UM 43.6 71 22 5.5 0.6 1.2 2.6 0.44 MMD115.5UM, rep. 1 44.2 86 33 5.8 0.9 1.0 2.8 0.41 Mean: 43.9 78.5 27.5 5.7 0.8 1.1 2.7 0.4 Standard deviation: 0.3 7.5 5.5 0.1 0.1 0.1 0.1 0.0 Coefficient of variation: 0.7 9.6 20.0 2.7 20.0 9.1 3.7 3.5 MMD440.5LB 105.0 194 75 11.8 1.4 0.9 3.4 0.61 MMD440.5LB.rep. 1 84.1 160 60 10.0 1.9 1.0 2.6 0.40 Mean: 94.6 177.0 67.5 10.9 1.7 1.0 3.0 0.5 Standard deviation: 10.4 17.0 7.5 0.9 0.2 0.0 0.4 0.1 Coefficient of variation: 11.1 9.6 11.1 8.3 15.2 5.3 13.3 20.8 293 Table 16: continued.

SamplelD La Ce Nd Sm Eu Tb Yb Lu Units of measurement (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) Method of Analysis INAA INAAINAA INAA INAAINAA INAA INAA Method Detection Level 0.5 3 5 0.1 0 2 0 5 0 2 0.05 MPU241.5UB 30.2 63 30 4.6 1.1 0.6 2.0 0.34 MPU241.5UB, rep. 1 27.2 52 24 4.8 1.0 0.6 2.0 0.32 Mean: 28.7 57.5 27.0 4.7 1.1 0.6 2.0 0.3 Standard deviation: 1.5 5.5 3.0 0.1 0.1 0.0 0.0 0.0 Coefficient of variation: 5 2 9.6 11.1 2.1 4.8 0.0 0.0 3.0 MA5152.0UB 35.1 69 32 5.6 1.1 0.9 3.9 0.60 MAR152.0UB.rep. 1 32.3 64 29 5.6 1.7 0.7 3.7 0.60 Mean: 33.7 66.5 30.5 5.6 1.4 0.8 3.8 0.6 Standard deviation: 1.4 2.5 1.5 0.0 0.3 0.1 0.1 0.0 Coefficient of variation: 4.2 3.8 4.9 0.0 21.4 12.5 2.6 0.0 LPP54.5UB 41.3 90 46 6.8 1.5 0.9 4.6 0.68 LPP54.5UB, rep. 1 42.0 96 38 7.7 1.2 1.2 4.0 0.63 Mean: 41.7 93.0 42.0 7.3 1.4 1.1 4.3 0.7 Standard deviation: 0.4 3.0 4.0 0.5 0.1 0.1 0.3 0.0 Coefficient of variation: 0.8 32 9.5 6 2 11.1 14.3 7.0 3.8 Mean coefficient of variation 3.8 5.1 7.7 4.4 14.2 8.8 4.5 5.8 294 Table 17: Complete results of elemental analyses for major, minor and rare earth elements from the Beardmore Glacier Region, Antarctica. Sample ID follows the convention established in Figure 6.

SamplelD Si02 A1203 CaO Na20 K20 P2Q5 Fe203 MgO Mn T i02 Be B Sc PAGODA MMP1.5LP 67.0 15.2 0.86 1.65 3.11 0.15 5.43 2.56 400 0.71 4 40 12.4 CPZ16.3LP 54.1 20.4 0.50 0.29 3.94 0.23 10.80 3.96 1600 1.21 7 10 20.9 CPZ46.1LP 62.5 18.1 0.89 0.94 3.43 0.16 6.83 3.24 420 0.70 5 50 18.0 MTM129.0LP 67.8 14.6 0.74 1.38 3.41 0.17 4.87 2.59 380 0.68 5 70 12.8 TGA41.0LP 64.7 15.5 0.80 1.72 3.22 0.16 5.79 2.86 700 0.66 4 70 13.4 Average: 63.2 16.8 0.76 1,20 3.42 0.17 6.74 3.04 700 0.79 5 48 15.5 Standard dev.: 4.9 2.2 0.14 0.53 0.29 0.03 2.13 0.52 465 0.21 1 22 3.4

MMP74.5UP 55.8 18.3 0.72 0.98 4.65 0.17 10.60 4.07 630 1.14 8 10 20.1 MMC17.6UP 72.7 12.5 0.65 1.23 3.19 0.13 4.18 1.50 340 0.56 4 10 10.4 MTM186.2UP 65.6 15.1 1.02 1.26 3.17 0.16 5.65 2.54 610 0.70 6 60 13.6 MTM213.5UP 55.7 19.1 0.55 0.59 4.26 0.37 8.82 3.86 560 0.86 6 30 21.0 TGA96.7UP 66.1 15.1 0.86 1.76 3.14 0.15 5.80 2.75 430 0.71 5 70 14.0 Average: 63.2 16.0 0.76 1.16 3.68 0.20 7.01 2.94 514 0.79 6 36 15.8 Standard dev.: 6.6 2.4 0.16 0.38 0.64 0.09 2.34 0.94 111 0.20 1 25 4.1 Entire Pagoda Average: 63.2 16.4 0.76 1.18 3.55 0.19 6.88 2.99 607.0 0.79 5.4 42.0 15.7 Standard dev.: 5.8 2.3 0.15 0.46 0.51 0.07 2.24 0.76 350.6 0.20 1.3 24.4 3.7 MACKELLAR MKR6.0LM 59.3 17.7 0.50 1.17 3.78 0.16 7.20 3.54 370 0.78 6 90 18.1 MMA6.6LM 57.4 18.3 0.66 0.76 3.69 0.21 8.78 3.43 550 0.76 6 30 17.4 MMC20.5LM 58.5 20.8 0.56 0.43 4.23 0.35 6.36 2.98 440 0.72 8 20 16.4 TRMO.OLM 67.0 14.4 0.66 1.31 3.28 0.15 5.51 2.48 390 0.73 6 60 14.1 CPZ123.4LM 65.4 15.5 0.97 1.20 2.94 0.21 6.64 2.88 480 0.69 5 80 15.5 TGA151.7LM 55.6 19.2 0.77 1.07 4.19 0.17 9.18 3.93 640 0.91 6 40 19.4 TGA160.0LM 56.5 19.2 1.04 1.05 3.83 0.26 9.15 3.70 600 0.80 6 40 17.7 MB038.5LM 60.4 15.7 1.05 2.69 3.06 0.21 7.08 3.13 700 0.89 5 30 16.5 CHI132.6LM 56.8 18.6 0.04 0.89 4.20 0.18 8.77 3.63 1000 0.84 6 40 18.0 MDK10.7LM 67.3 13.8 2.04 1.23 2.50 0.76 6.39 2.54 700 0.70 6 50 15.8 MDK20.5LM 62.7 15.4 2.09 2.43 2.95 0.23 7.69 2.78 920 0.82 4 30 14.8 Average: 60.6 17.1 0.94 1.29 3.51 0.26 7.52 3.18 617 0.79 6 46 16.7 Standard dev.: 4.1 2.2 0.59 0.64 0.57 0.17 1.22 0.47 195 0.07 1 21 1.5

MKR42.2MM 56.0 18.5 0.80 0.60 3.64 0.19 7.46 3.54 700 0.75 6 70 17.4 MMQ4.3MM 55.7 20.0 0.60 1.23 4.08 0.27 7.98 3.56 480 0.84 7 50 19.1 MMQ33.0MM 54.6 20.0 1.07 1.07 3.84 0.30 9.04 3.64 660 0.95 8 40 17.1 MMA59.8MM 63.0 17.3 0.85 1.33 3.48 0.18 5.89 2.68 350 0.79 6 50 14.8 MMC49.1MM 65.3 16.3 0.77 1.17 3.18 0.18 6.36 2.66 350 0.86 6 20 15.7 MMC74.8MM 57.9 18.9 0.98 0.38 4.57 0.62 8.29 3.52 530 0.87 7 10 19.8 MMD11.0MM 55.1 18.1 1.57 0.94 3.93 0.98 8.78 3.95 900 0.78 6 80 17.0 295 Table 17: continued.

SamplelD Si02 A1203 CaO Na20 K20 P205 Fe203 MgO Mn T I02 Be B Sc MMD27.0MM 59.2 18.1 1.05 1.04 3.15 0.14 6.35 2.73 500 0.68 6 50 14.9 TRM27.5MM 61.7 17.0 0.44 1.05 3.51 0.19 7.20 3.24 400 0.77 6 80 16.2 CPZ145.9MM 68.4 13.7 0.97 1.17 2.62 0.18 5.69 2.67 360 0.74 6 70 13.8 MTM246.2MM 58.4 19.3 0.22 0.62 4.38 0.11 7.26 3.33 350 0.80 7 60 19.9 TGA173.0MM 61.4 17.5 0.45 1.27 4.02 0.16 6.70 3.33 340 0.72 5 70 18.0 TGFO.OMM 56.1 19.5 0.26 0.27 5.31 0.13 8.70 3.45 480 0.85 6 30 19.5 MB067.8M M 56.4 18.0 0.62 2.18 4.13 0.20 7.68 3.56 410 1.08 6 40 19.9 CHI178.5MM 58.5 17.6 1.03 1.12 2.76 0.32 9.01 3.37 410 0.84 5 40 16.9 Average: 59.2 18.0 0.78 1.03 3.77 0.28 7.49 3.28 481 0.82 6 51 17.3 Standard dev.: 3.9 1.6 0.35 0.44 0.68 0.22 1.09 0.39 155 0.10 1 20 1.9

MKR58.5UM 65.4 18.1 0.19 1.66 3.26 0.08 3.96 2.23 390 0.81 5 60 16.2 MMA73.2UM 68.2 14.5 0.88 1.55 2.96 0.17 5.08 2.15 370 0.66 5 30 11.0 MMC117.5UM 63.0 16.4 0.60 0.97 3.47 0.14 7.65 3.03 390 0.76 8 60 16.0 MMD75.5UM 64.6 16.2 0.50 1.27 3.22 0.17 5.70 2.48 300 0.75 7 40 13.8 MMD115.5UM 53.6 20.0 0.25 0.68 4.70 0.12 9.23 4.06 700 0.72 6 60 20.7 CPZ176.1UM 66.1 15.2 0.89 1.29 3.26 0.17 5.86 2.85 540 0.63 5 70 15.1 MTM269.0UM 58.0 19.1 0.22 0.62 4.38 0.14 8.02 3.43 490 0.84 7 50 19.8 TGA228.0UM 60.5 17.5 0.45 1.27 4.02 0.17 7.22 3.08 360 0.77 5 30 18.4 MBO88.0UM 58.5 17.1 0.52 1.93 3.70 0.10 7.40 2.99 350 0.95 5 30 16.7 MB0104.0UM 61.7 15.6 0.63 2.53 3.22 0.22 6.89 2.77 260 0.84 4 30 13.5 MBO125 0UM 60.8 16.4 0.46 2.57 3.51 0.18 6.17 2.73 500 0.96 6 30 17.0 MDK119.0UM 60.8 17.2 0.88 0.86 3.78 0.15 8.51 2.47 400 0.87 6 70 18.0 Average: 61.8 16.9 0.54 1.43 3.62 0.15 6.81 2.86 421 0.80 6 47 16.4 Standard dev.: 3.9 1.5 0.24 0.62 0.50 0.04 1.45 0.51 114 0.10 1 16 2.6 Entire Mackellar Average: 60.4 17.4 0.75 1.23 3.65 0.23 7.29 3.12 501.6 080 5.9 48.2 16.8 Standard dev.: 4.1 1.8 0.44 0.59 0.61 0.18 1.29 0.49 175.5 0.09 0.9 19.4 2.1 FAIRCHILD MKR90.5LF 71.0 13.6 0.58 1.28 3.11 0.14 4.54 1.61 550 0.75 4 20 11.5 MMA87.0LF 66.6 14.8 0.68 1.30 3.70 0.15 5.80 2.19 840 0.70 5 30 12.2 TRM71.6LF 66.5 15.1 0.35 0.92 3.08 0.16 6.54 2.52 370 0.76 5 60 13.4 TGF136.0F 62.7 19.0 0.30 1.27 4.18 0.13 5.10 2.39 220 1.00 5 70 19.1 M B0170.0UF 52.5 17.1 0.37 1.45 3.21 0.13 11.50 2.86 640 0.99 8 20 21.4 MDK209.0F? 64.3 16.1 1.23 1.62 3.19 0.23 5.96 2.67 360 0.90 6 60 14.6 Entire Fairchild Average: 63.9 16.0 0.59 1.31 3.41 0.16 6.57 2.37 496.7 0.85 5.5 43.3 15.4 Standard dev.: 5.7 1.7 0.32 0.21 0.40 0.03 2.29 0.40 205.2 0.12 1.3 20.5 3.6 BUCKLEY MMD270.0LB 52.0 17.9 0.25 0.92 2.48 0.11 8.99 2.06 500 0.87 5 50 15.5 MMD283.5LB 48.2 19.5 1.17 0.72 3.30 0.15 5.35 2.63 210 1.13 7 30 24.8 MMD295.5LB 17.2 9.3 2.98 0.61 0.94 0.02 0.51 1.12 72 0.67 10 20 29.1 MMD318.SLB 18.3 10.2 2.21 0.01 0.57 0.03 0.23 0.73 72 0.78 5 20 10.7 MMD384.0LB 2.7 1.1 0.09 0.05 0.03 0.03 0.28 0.68 26 0.11 14 10 12.7 296 Table 17: continued.

SamplelD Si02 A1203 CaO Na20 K20 P205 Fe203 MgO Mn Ti02 Be B Sc MMD417.0LB 45.8 17.2 1.24 0.25 1.86 0.05 3.90 1.42 300 0.75 4 20 13.0 MMD440.5LB 48.0 20.5 0.74 0.44 2.34 0.06 3.07 1.69 160 0.90 5 30 15.3 TGF218.0LB 58.8 21.4 0.30 0.97 4.14 0.14 5.66 2.32 200 1.04 5 30 21.8 MPI28.6LB 64.4 17.9 0.20 1.62 3.33 0.08 3.83 2.13 210 0.77 5 30 16.2 MTR13.1LB 49.9 24.9 0.41 0.27 4.04 0.06 3.29 1.51 150 1.07 10 30 32.4 MTR61.1LB 52.9 19.7 0.67 0.97 3.35 0.11 5.31 1.94 350 0.91 5 30 16.6 MA614.4LB 63.4 19.8 0.16 1.57 3.90 0.06 3.76 2.20 78 0.84 4 30 18.2 MA645.2LB 70.8 16.4 0.51 0.86 3.78 0.04 1.25 0.84 52 0.64 4 30 12.9 MA551.7LB 66.2 18.3 0.86 1.10 2.85 0.07 1.66 1.02 92 0.77 4 40 14.3 BOB27.5LB 58.6 18.1 0.51 1.33 3.05 0.10 5.30 2.05 230 0.95 3 30 17.7 BOB89.8LB 48.0 18.7 0.60 1.40 2.77 0.09 5.27 1.75 300 0.77 6 20 21.3 BOB116.1LB 51.6 22.1 0.47 0.90 2.95 0.11 4.04 1.66 110 0.93 5 30 20.4 Average: 48.0 17.2 0.79 0.82 2.69 0.08 3.63 1.63 183.1 0.82 5.9 28.2 18.4 Standard dev.: 18.0 5.5 0.74 0.49 1.18 0.04 2.26 0.57 121.9 0.22 2.8 8.6 5.8

WLG58.0UB 51.4 10.3 0.08 0.60 2.31 0.04 2.15 0.86 86 0.49 2 20 9.3 MPI53.1UB 64.4 21.6 0.41 0.81 3.56 0.10 1.28 0.78 60 0.91 6 30 19.0 MPI54.0UB 57.7 14.8 0.46 0.67 2.29 0.04 0.41 0.95 40 0.66 5 20 9.1 MPU40.4UB 74.4 13.1 0.43 0.33 5.84 0.03 0.94 0.57 100 0.47 3 20 8.6 MPU117.3UB 72.5 12.0 0.33 0.59 5.20 0.05 1.77 0.47 300 0.40 4 20 9.0 MPU159.4UB 44.9 8.4 0.33 0.48 3.84 0.08 0.33 0.22 52 0.40 3 20 4.2 MPU183.8UB 44.2 7.9 0.17 0.87 1.85 0.06 0.18 0.46 42 0.29 4 20 5.4 MPU214.2UB 69.3 15.7 0.48 0.81 1.89 0.05 0.55 0.44 54 0.66 4 50 4.5 MPU241.5UB 66.8 17.9 1.06 2.01 3.36 0.13 1.05 0.79 72 0.88 3 30 10.7 MTR130.5UB 60.7 13.4 0.43 1,23 1.80 0.15 9.42 1.83 1500 0.54 7 10 12.9 MTR159.5UB 55.3 18.3 0.40 0.90 5.09 0.09 2.99 1.05 210 0.84 3 30 14.3 MTR203.7UB 69.1 4.1 0.08 0.01 2.76 0.02 0.65 0.10 30 0.08 2 10 1.9 MA6131.2UB 64.5 7.4 0.17 0.04 5.56 0.02 0.19 0.10 52 0.33 3 10 5.8 MA5114.1UB 66.0 19.1 0.27 1.28 3.24 0.03 1.33 0.88 88 0.55 4 40 9.4 MA5152.0UB 70.8 16.2 0.38 1.96 2.55 0.06 0.82 0.82 92 0.47 2 30 8.6 MA49.2UB 85.4 5.5 0.21 0.31 3.22 0.03 0.17 0.26 34 0.17 5 10 2.0 MA437.0UB 60.3 20.8 0.99 2.95 3.87 0.15 2.28 0.89 460 0.97 4 40 13.4 LPP28.0UB 66.0 19.4 0.76 1.40 4.63 0.11 0.88 0.64 96 0.70 4 20 14.9 LPP54.5UB 60.7 23.4 0.71 0.44 6.52 0.17 0.79 0.63 420 0.92 4 20 13.3 Average: 63.4 14.2 0.4 0.9 3.7 0.1 1.5 0.7 199.4 0.6 3.8 23.7 9.3 Standard dev.: 9.8 5.6 0.3 0.7 1.4 0.0 2.0 0.4 331.0 0.3 1.3 10.9 4.5 Entire Buddey Average: 56.1 15.6 0.6 0.9 3.2 0.1 2.5 1.1 191.7 0.7 4.8 25.8 13.6 Standard Dev. 16.2 5.7 0.6 0.6 1.4 0.0 2.4 0.7 254.8 03 2.4 10.1 6.9 297 Table 17: continued.

SamplelD V Cr Co Ni Cu Zn Ge As Se Br Mo Ag Cd Sb Cs PAGODA MMP1.5LP 90 77 12 37 23.0 91.0 10 2 3 2 5 0.5 1 0.3 5.8 CPZ16.3LP 200 150 23 61 52.0 260.0 10 10 3 1 5 0.5 1 0.3 13.3 CPZ46.1LP 140 110 15 42 34.0 110.0 10 2 3 2 5 0.5 1 0.2 5.4 MTM129.0LP 100 78 12 33 23.0 81.0 10 4 3 2 5 0.5 1 0.3 6.4 TGA41.0LP 94 76 12 51 31.0 110.0 10 5 3 1 5 0.5 1 0.3 9.0 Average: 125 98 15 45 32.6 130.4 10 5 3 2 5 0.5 1 0.3 8.0 Standard dev.: 42 29 4 10 10.6 65.8 0 3 0 0 0 0.0 0 0.0 2.9

MMP74.5UP 200 150 60 95 70.0 180.0 10 42 3 2 5 0.5 1 1.1 16.0 MMC17.6UP 72 58 9 21 16.0 65.0 10 2 3 3 5 0.5 1 0.2 3.0 MTM186.2UP 100 86 13 37 25.0 82.0 10 4 3 3 5 0.5 1 0.4 7.0 MTM213.5UP 160 150 27 79 54.0 130.0 10 62 3 2 5 0.5 1 0.5 9.8 TGA96.7UP 92 79 12 33 21.0 85.0 10 5 11 1 5 0.5 2 0.2 5.4 Average: 125 105 24 53 37.2 108.4 10 23 5 2 5 0.5 1 0.5 8.2 Standard dev.: 48 38 19 29 21.1 41.8 0 25 3 1 0 0.0 0 0.3 4.5 Entire Pagoda Average: 124.8 101.4 19.5 48.9 34.9 119.4 10.0 13.8 3.8 1.9 5.0 0.5 1.1 0.4 8.1 Standard dev.: 44.8 34.0 14.5 21.9 16.8 56.2 0.0 19.7 2.4 0.7 0.0 0.0 0.3 0.3 3.8 MACKELLAR MKR6.0LM 150 120 18 52 36.0 120.0 10 2 3 2 5 0.5 1 0.4 10.5 MMA6.6LM 160 120 19 51 29.0 120.0 10 4 3 3 5 0.5 1 0.4 4.6 MMC20.5LM 120 110 17 46 29.0 110.0 10 12 3 3 5 0.5 1 0.5 8.9 TRMO.OLM 94 90 13 37 28.0 94.0 10 3 3 2 5 0.5 1 0.4 8.1 CPZ123.4LM 130 100 17 47 24.0 110.0 10 8 3 2 5 0.5 1 0.5 6.7 TGA151.7LM 160 130 27 63 54.0 130.0 10 27 3 1 5 0.5 2 0.6 9.0 TGA160.0LM 140 110 19 52 45.0 140.0 10 2 9 1 5 0.5 2 0.6 10.0 MB038.5LM 120 100 18 77 55.0 120.0 10 2 12 1 5 0.5 1 0.3 8.1 CHI132.6LM 140 110 20 74 62.0 130.0 10 6 3 1 5 0.5 1 0.6 15.7 MDK10.7LM 120 110 14 42 45.0 93.0 10 6 3 3 5 0.5 1 0.5 5.2 MDK20.5LM 130 110 21 60 32.0 110.0 10 7 3 1 5 0.5 I 0.3 5.5 Average: 133 n o 18 55 39.9 116.1 10 7 4 2 5 0.5 1 0.5 8.4 Standard dev.: 19 10 4 12 12.3 13.9 0 7 3 1 0 0.0 0 0.1 3.0

MKR42.2MM 120 110 17 74 45.0 120.0 10 3 5 1 5 0.5 1 0.6 17.5 MMQ4.3MM 150 120 18 52 36.0 120.0 10 3 3 3 5 0.5 1 0.9 9.3 MMQ33.0MM 150 130 22 59 45.0 130.0 10 3 3 2 5 0.5 1 0.4 11.2 MMA59.8MM 110 97 14 41 25.0 96.0 10 2 3 2 5 0.5 1 0.3 5.9 MMC49.1MM 120 100 17 47 33.0 110.0 10 2 3 3 5 0.5 1 0.4 4.8 MMC74.8MM 150 150 19 62 43.0 110.0 10 2 3 2 5 0.5 1 0.6 12.8 MMD1 l.OMM 140 120 22 66 47.0 140.0 10 7 5 1 5 0.5 1 0.4 14.6 298 Table 17: continued.

SamplelD V Cr Co Ni Cu Zn Ge As Se Br Mo Ag Cd Sb Cs MMD27.0MM 110 94 14 39 24.0 98.0 10 6 3 1 5 0.5 1 0.7 6.3 TRM27.5MM 140 n o 14 45 28.0 100.0 20 2 3 2 5 0.5 1 0.4 8.0 CPZ145.9MM 98 100 15 48 31.0 95.0 10 4 3 2 5 0.5 1 0.4 6.8 MTM246.2MM 140 130 15 44 38.0 110.0 10 14 3 2 5 0.5 1 0.6 13.4 TGA173.0MM 130 110 15 45 35.0 110.0 10 2 3 2 5 0.5 1 0.4 11.2 TGFO.OMM 160 140 26 63 41.0 130.0 10 7 3 2 5 0.5 1 0.7 17.5 M B067.8MM 170 150 23 71 53.0 130.0 10 2 5 1 5 0.5 2 0.2 8.5 CHI178.5MM 140 130 23 62 49.0 150.0 10 2 3 3 5 0.5 1 0 3 10.9 Average: 135 119 18 55 38.2 116.6 11 4 3 2 5 0,5 1 0.5 10.6 Standard dev.: 20 18 4 11 8.6 16.1 2 3 1 1 0 0.0 0 0.2 3.9

MKR58.5UM 120 110 15 42 29.0 100.0 10 5 3 3 5 0.5 1 0.5 8.5 MMA73.2UM 77 74 12 32 18.0 86.0 10 2 3 2 5 0.5 1 0.2 4.5 MMC117.5UM 120 110 18 49 35.0 120.0 10 3 3 2 50.5 10.3 9.4 MMD75.5UM 87 100 14 39 25.0 97.0 10 5 3 3 5 0.5 1 0.6 6.3 MMD115.5UM 150 130 18 79 54.0 140.0 10 4 3 1 5 0.5 1 0.5 14.6 CPZ176.1UM no 100 14 44 29.0 93.0 10 2 3 3 5 0.5 1 0.7 6.4 MTM269.0UM 150 140 22 62 45.0 130.0 10 2 3 2 5 0.5 1 0.7 11.2 TGA228.0UM 130 140 18 61 37.0 110.0 10 3 3 3 5 0.5 1 0.4 15.1 MBO88.0UM 120 130 13 52 49.0 120.0 10 2 3 2 5 0.5 1 0.2 7.6 MB0104.0UM 100 96 14 45 29.0 96.0 10 2 4 1 5 0.5 1 0.2 3.1 MB0125.0UM 120 110 15 71 53.0 130.0 10 2 12 3 5 0.5 1 0.3 10.5 MDK119.0UM 140 120 17 46 27.0 110.0 10 2 8 1 5 0.5 1 0.2 7.3 Average: 119 113 16 52 35.8 111.0 10 3 4 2 5 0.5 1 0.4 8.7 Standard dev.: 22 19 3 13 11.3 16.4 0 1 3 1 0 0.0 0 0.2 3.5 Entire Mackellar Average: 129.4 114.8 17.6 53.7 37.9 114.7 10.3 4.6 3.9 2.0 5.0 0.5 1.1 0.5 9.4 Standard dev.; 21.4 16.9 3.6 12.1 10.8 15.8 1.6 4.6 2.3 0.8 0.0 0.0 0.3 0.2 3.7 FAIRCHILD MKR90.5LF 100 82 11 28 22.0 91.0 10 2 3 1 5 0.5 1 0.2 4.1 MMA87.0LF n o 87 13 38 26.0 93.0 10 4 3 3 5 0.5 1 0.2 3.8 TRM71.6LF 110 90 14 43 28.0 89.0 10 2 3 1 5 0.5 1 0.3 5.7 TGF136.0F 130 120 16 47 38.0 130.0 10 2 3 4 5 0.5 1 0.3 8.4 M B0170.0UF 170 150 26 76 57.0 130.0 10 2 3 5 5 0.5 1 0.2 4.4 MDK209.0F? 130 100 17 43 24.0 100.0 10 4 3 2 5 0.5 1 0.2 6.0 Entire Fairchild Average: 125.0 104.8 16.2 45.8 32.5 105.5 10.0 2.7 3.0 2.7 5.0 0.5 1.0 0.2 5.4 Standard dev.: 22.9 23.6 4.8 14.8 12.1 17.7 0.0 0.9 0.0 1.5 0.0 0.0 0.0 0.0 1.6 BUCKLEY MMD270.0LB 120 100 20 82 40.0 170.0 20 3 3 1 5 0.5 1 0.2 7.9 MMD283.5LB 180 180 22 69 73.0 160.0 10 2 3 8 5 0.5 1 0.2 8.2 MMD295.5LB 240 620 33 64 29.0 73.0 30 2 3 6 5 0.5 1 0.3 2.5 MMD318.5LB 120 130 11 67 62.0 22.0 10 2 4 1 5 0.5 1 0.3 6.0 MMD384.0LB 96 120 15 28 3.5 4.0 10 2 3 1 5 0.5 1 0.2 0.5 299 Table 17: continued.

Sam plelD V Cr Co Ni Cu Zn Ge As Se Br M o Ag Cd Sb Cs MMD417.0LB 120 120 10 84 64.0 83.0 10 2 3 4 5 0.5 1 0.2 11.7 MMD440.5LB 100 140 10 60 79.0 77.0 10 2 3 4 5 0.5 1 0.2 6.8 TGF218.0LB 160 170 17 72 80.0 130.0 10 2 3 3 5 0.5 1 0.3 5.4 MPI28.6LB 96 120 12 54 24,0 110.0 10 2 3 3 5 0.5 1 0.3 8.4 MTR13.1LB 360 270 18 80 85.0 140.0 10 2 3 8 5 0.5 1 0.2 8.8 MTR61.1LB 150 130 26 130 78.0 140.0 10 2 3 6 5 0.5 1 0.4 9.0 MA614.4LB 100 130 11 46 22.0 110.0 10 2 3 1 5 0.5 1 0.7 7.9 MA64S.2LB 86 67 6 14 29.0 42.0 10 21 3 2 5 0.5 1 0.7 12.6 MA551.7LB 86 61 7 30 36.0 92.0 10 2 3 2 5 0.5 1 0.6 9.3 BOB27.5LB 98 120 18 54 33.0 110.0 10 2 3 5 5 0.5 1 0.2 7.9 BOB89.8LB 94 120 14 84 48.0 110.0 10 2 3 3 5 0.5 1 0.2 7.6 BOB116.1LB 170 180 21 n o 70.0 95.0 10 2 3 4 5 0.5 1 0.2 5.8 Average: 139.8 163.4 15.9 66.4 50.3 98.1 11.8 3.2 3.1 3.6 5.0 0.5 1.0 0.3 7.4 Standard dev.: 68.3 123.1 6.9 28.0 24.4 44.2 5.1 4.5 0.2 2.2 0.0 0.0 0.0 0.2 2.8

WLG58.0UB 76 23 9 18 26.0 74.0 10 3 3 5 5 0.5 1 0.6 11.0 MPI53.1UB 86 36 5 15 18.0 110.0 10 5 3 3 5 0.5 1 0.2 6.2 MPI54.0UB 42 12 2 8 8.0 38.0 10 4 3 8 5 0.5 1 0.2 2.9 MPU40.4UB 46 19 2 7 10.0 45.0 10 2 3 3 5 0.5 1 0.3 5.2 MPU117.3UB 50 20 3 10 9.5 60.0 10 8 3 3 5 0.5 1 0.6 6.4 MPU159.4UB 50 14 3 4 7.5 38.0 10 2 3 14 5 0.5 1 0.3 3.4 MPU183.8UB 24 3 2 8 4.5 44.0 10 3 3 13 5 0.5 1 0.4 2.8 MPU214.2UB 40 21 2 9 11.0 49.0 10 6 3 5 5 0.5 1 0.3 8.4 MPU241.5UB 110 29 8 10 27.0 55.0 10 7 3 4 5 0.5 1 0.6 6.6 MTR130.5UB 90 68 22 46 31.0 100.0 10 2 3 8 5 0.5 1 0.2 4.4 MTR159.5UB 120 140 10 53 72.0 110.0 10 9 3 5 5 0.5 1 0.4 8.0 MTR203.7UB 10 4 2 3 1.5 14.0 10 2 3 6 5 0.5 1 0.2 0.5 MA6131.2UB 32 7 2 3 5.5 28.0 10 6 3 3 5 0.5 1 0.3 0.9 MA5114.1UB 28 13 1 4 9.5 79.0 10 2 6 1 6 0.5 1 0.5 17.1 MA5152.0UB 30 17 3 6 7.0 84.0 10 2 3 3 5 0.5 1 0.3 8.3 MA49.2UB 32 7 3 6 8.5 27.0 10 2 3 7 5 0.5 1 0.2 1.1 MA437.0UB 64 12 6 7 26.0 83.0 10 15 5 2 6 0.5 1 1.2 6.6 LPP28.0UB 58 17 3 8 22.0 94.0 10 6 3 1 5 0.5 1 0.4 8.1 LPP54.5UB 59 15 12 8 22.0 66.0 10 18 3 3 5 0.5 1 0.7 9.8 Average: 55.1 25.1 5-3 12.3 17.2 63.1 10.0 5.5 3.3 5.1 5.1 0.5 1.0 0.4 6.2 Standard dev.: 28.9 30.5 5.0 13.3 15.6 28.2 0.0 4.4 0.8 3.5 0.3 0.0 0.1 0.2 3.9 Entire Buckley Average: 95.1 90.4 10.3 37.8 32.8 79.6 10.8 4.4 3.2 4.4 5.1 0.5 1.0 0.4 6.8 Standard Dev. 66.6 111.4 8.0 34.5 26.1 40.6 3.6 4.6 0.6 3.1 0.2 0.0 0.1 0.2 3.5 300

Table 17: continued.

SamplelD Hf Ta W Ir Au Pb Th U La Ce Nd Sm Eu Tb Yb Lu PAGODA MMP1.5LP 8 1 3 20 10 22 16.0 4.2 56.3 105 45 6.5 1.3 0.9 2.8 0.43 CPZ16.3LP 3 1 3 20 10 30 36.0 6.3 90.3 172 56 8.3 1.3 1.2 2.4 0.47 CPZ46.1LP 5 1 3 20 10 20 18.0 3.7 53.6 105 41 6.6 1.2 1.0 3.0 0.45 MTM129.0LP 8 1 3 20 10 20 14.0 2.8 52.9 107 42 6.9 1.3 0.8 3.0 0.47 TGA41.0LP 6 1 3 20 5 22 15.0 3.5 54.3 88 29 7.3 0.9 1.7 3.0 0.53 Average: 6 1 3 20 9 23 19.8 4.1 61.5 115 43 7.1 1.2 1.1 2.8 0.47 Standard dev.: 2 0 0 0 2 4 8.2 1.2 14.5 29 9 0.7 0.2 0.3 0.2 0.03

MMP74.5UP 2 1 3 20 10 30 34.0 5.0 82.6 169 60 9.3 1.4 1.1 2.5 0.41 MMC17.6UP 10 1 3 20 10 10 12.0 2.3 39.1 78 30 4.8 1.0 0.6 2.2 0.36 MTM186.2UP 7 1 3 20 10 18 16.0 3.7 54.3 106 45 6.7 1.3 0.9 3.0 0.47 MTM213.5UP 4 1 5 20 10 42 31.0 8.2 76.8 157 84 10.8 2.1 1.9 3.9 0.63 TGA96.7UP 7 1 3 20 5 16 17.0 4.0 59.0 107 52 7.8 1.5 0.7 3.3 0.65 Average: 6 1 3 20 9 23 22.0 4.6 62.4 123 54 7.9 1.5 1.0 3.0 0.50 Standard dev.: 3 0 1 0 2 11 8.8 2.0 15.7 34 18 2.1 0.4 0.5 0.6 0.12 Entire Pagoda Average: 6.0 1.0 3.2 20.0 9.0 23.0 20.9 4.4 61.9 119.4 48.4 7.5 1.3 1.1 2.9 0.49 Standard dev.: 2.4 0.0 0.6 0.0 2.0 8.5 8.6 1.7 15.1 32.0 15.2 1.6 0.3 0.4 0.5 0.09 MACKELLAR MKR6.0LM 5 1 3 20 10 22 16.0 3.8 60.0 115 48 7.4 1.4 1.1 3.0 0.48 MMA6.6LM 4 1 3 20 10 20 23.0 5.1 66.2 123 41 7.5 1.6 1.2 2.9 0.48 MMC20.5LM 3 1 3 20 10 18 26.0 5.9 91.7 176 79 10.7 1.9 1.6 3.3 0.52 TRM0.0LM 7 1 3 20 10 16 15.0 3.3 48.0 94 39 6.0 1.3 0.9 3.0 0.42 CPZ123.4LM 7 1 3 20 10 24 14.0 3.3 48.3 98 42 6.9 1.4 0.9 3.1 0.48 TGA151.7LM 4 1 3 20 5 32 33.0 6.2 69.2 135 43 9.2 1.2 0.7 3.7 0.64 TGA160.0LM 5 1 3 20 5 30 29.0 5.4 96.1 172 56 11.4 1.8 1.1 3.9 0.63 MB038.5LM 8 3 3 20 9 22 19.0 6.3 83.3 117 5 9.0 1.5 0.7 2.8 0.73 CHH32.6LM 3 1 3 20 5 32 24.0 6.5 72.9 119 42 8.3 0.8 1.3 3.0 0.56 MDK10.7LM 6 1 3 20 10 22 16.0 5.3 57.6 122 81 12.0 2.6 2.2 4.1 0.63 MDK20.5LM 6 I 3 20 5 20 20.0 6.5 83.9 145 51 9.9 1.4 1.3 2.9 0.63 Average: 5 1 3 20 8 23 21.4 5.2 70.7 129 48 8.9 1.5 1.2 3.2 0.56 Standard dev.: 2 1 0 0 2 5 5 .9 1.2 15.8 25 20 1.8 0.4 0.4 0.4 0.09

MKR42.2MM 4 1 3 20 9 30 21.0 4.2 65.0 104 40 8.1 0.6 1.2 3.2 0.55 MMQ4.3MM 5 1 4 20 10 28 23.0 5.1 68.8 132 54 9.1 1.7 1.1 3.4 0.48 MMQ33.0MM 4 1 3 20 10 30 30.0 4.8 70.8 134 54 7.9 1.9 1.3 2.5 0.44 MMA59.8MM 8 1 3 20 10 24 20.0 4.9 71.2 133 62 7.9 1.5 1.1 3.2 0.53 MMC49.1MM 11 1 3 20 10 16 18.0 4.3 65.1 126 60 8.0 1.5 1.4 3.8 0.60 MMC74.8MM 3 1 3 20 10 18 26.0 6.8 77.4 155 89 12.5 2.3 2.0 3.9 0.57 MMD11.0MM 2 1 3 20 5 38 25.0 5.6 97.1 192 70 21.6 1.9 3.8 3.9 0.62 301 Table 17: continued.

SamplelD Hf Ta w Ir Au Pb Th U La Ce Nd Sm Eu Tb Yb Lu I MMD27.0MM 4 1 3 20 5 22 23.0 5.6 79.5 141 51 8.4 1.5 0.5 2.9 0.58 TRM27.5MM 6 1 3 20 10 16 16.0 3.7 55.7 106 44 7.0 1.7 1.4 3.2 0.50 CPZ145.9MM 8 1 3 20 10 24 14.0 2.9 48.8 97 41 6.6 1.5 1.2 3.1 0.47 MTM246.2MM 5 1 3 20 10 18 22.0 5.2 61.0 116 53 6.8 1.4 1.1 3.4 0.51 TGA173.0MM 6 1 3 20 10 18 16.0 3.2 48.1 94 40 6.2 1.2 0.8 2.9 0.46 TGF0.0MM 13 1 3 20 10 30 30.0 6.5 68.0 128 43 7.0 1.4 1.0 3.7 0.57 MB067.8MM 4 1 3 20 5 18 26.0 5.9 90.2 156 61 10.2 1.8 1.3 2.9 0.62 CHI178.5MM 4 1 3 20 10 26 21.0 5.6 81.5 151 57 8.4 1.8 1.0 2.8 0.45 Average: 6 1 3 20 9 24 22.1 5.0 69.9 131 55 9.0 1.6 1.3 3.3 0.53 Standard dev.: 3 0 0 0 2 6 4.7 1.1 13.4 25 13 3.7 0.4 0.7 0.4 0.06

MKR58.5UM 5 1 3 20 10 12 17.0 3.4 53.7 103 40 6.7 1.2 1.0 2.9 0.45 MMA73.2UM 9 1 3 20 10 22 15.0 3.9 54.8 105 39 6.5 1.1 0.9 2.9 0.47 MMC117.5UM 7 1 3 20 10 10 16.0 5.0 58.5 113 51 7.4 1.6 1.1 3.2 0.50 MMD75.5UM 9 1 3 20 10 18 19.0 4.4 64.9 124 52 7.4 1.6 1.2 3.2 0.50 MMD115.5UM 4 1 3 20 5 26 17.0 3.7 43.6 71 22 5.5 0.6 1.2 2.6 0.44 CPZ176.1UM 5 1 3 20 10 16 13.0 2.9 40.9 82 36 5.8 1.2 0.8 2.7 0.41 MTM269.0UM 5 1 4 20 10 20 21.0 5.2 60.7 119 49 7.2 1.4 1.1 3.3 0.51 TGA228.0UM 6 1 3 20 10 10 18.0 4.6 50.5 96 42 6.6 1.4 1.4 3.2 0.50 MBO88.0UM 4 1 3 20 7 16 24.0 7.4 98.0 164 62 10.3 1.4 1.0 3.3 0.55 MB0104.0UM 6 1 3 20 11 14 18.0 4.3 72.2 130 50 9.1 1.3 1.2 2.8 0.47 MBO125.0UM 5 3 3 20 9 20 20.0 4.9 94.1 126 5 9.6 1.8 2.9 2.4 0.45 MDK.119.0UM 8 1 3 20 5 18 20.0 4.1 66.8 124 45 8.9 1.8 0.5 4.0 0.73 Average: 6 1 3 20 9 17 18.2 4.5 63.2 113 41 7.6 1.4 1.2 3.0 0.50 Standard dev.: 2 1 0 0 2 5 2.8 1.1 17.1 23 14 1.5 0.3 0.6 0.4 0.08 Entire Mackellai Average: 5.7 1.1 3.1 20.0 8.7 21.5 20.6 4.9 68.0 124.7 48.4 8.6 1.5 1.3 3.2 0.53 Standard dev.: 2.3 0.4 0.2 0.0 2.1 6.4 4.9 1.2 15.7 25.9 16.5 2.7 0.4 0.6 0.4 0.08 FAIRCHILD MKR90.5LF 8 1 3 20 10 14 14.0 3.7 50.3 98 36 6.1 1.4 0.8 2.8 0.46 MMA87.0LF 7 1 3 20 10 20 15.0 4.8 66.2 128 70 7.9 1.5 1.2 2.9 0.44 TRM71.6LF 8 1 3 20 10 6 14.0 3.7 49.2 96 40 6.5 1.3 0.9 2.9 0.48 TGF136.0F 10 1 3 20 10 32 19.0 3.9 61.2 119 52 7.6 1.6 0.8 3.8 0.59 MB0170.0UF 6 1 3 20 10 18 20.0 5.6 80.3 151 75 10.1 2.2 1.2 4.0 0.62 MDK209.0F? 11 1 3 20 10 14 17.0 4.7 59.3 113 45 6.8 1.0 0.9 2.9 0.43 Entire Fairchild Average: 8.3 1.0 3.0 20.0 10.0 17.3 16.5 4.4 61.1 117.5 53.0 7.5 1.5 1.0 3.2 0.50 Standard dev.: 1.7 0.0 0.0 0.0 0.0 7.9 2.4 0.7 10.5 18.7 14.7 1.3 0.4 0 2 0.5 0.07 BUCKLEY MMD270.0LB 6 1 3 20 5 22 15.0 2.9 66.1 112 41 8.9 1.6 0.9 2.9 0.51 MMD283.5LB 7 1 3 20 5 24 22.0 7.1 97.6 175 66 12.6 2.7 1.3 4.1 0.72 MMD295.5LB 5 1 3 20 5 20 14.0 2.5 12.2 28 10 3.1 1.2 1.2 8.0 1.71 MMD318.SLB 2 1 3 20 9 28 24.0 5.8 30.6 48 16 3.4 0.5 0.5 1.6 0.39 MMD384.0LB 1 1 3 20 5 10 1.7 0.5 34.2 79 43 10.3 2.0 1.7 6.8 1.41 302

Table 17: continued.

Sam ple® Hf Ta W Ir Au Pb Th U La Ce Nd Sm Eu Tb Yb Lu MMD417.0LB 4 1 3 20 5 24 17.0 3.1 45.9 69 17 5.0 1.2 0.7 2.7 0.55 MMD440.5LB 3 1 4 20 5 22 28.0 7.3 105.0 194 75 11.8 1.4 0.9 3.4 0.61 TGF218.0LB 6 1 3 20 10 20 22.0 4.8 89.8 173 63 9.7 2.1 1.5 3.4 0.51 MPI28.6LB 6 1 3 20 10 18 14.0 4.0 46.3 88 39 6.5 1.0 1.0 3.7 0.57 MTR13.1LB 3 1 3 20 10 26 24.0 3.6 77.5 163 74 11.9 2.9 1.9 6.5 0.95 MTR61.1LB 4 1 3 20 10 24 19.0 4.4 76.4 157 58 9.5 2.3 1.2 3.1 0.48 MA614.4LB 6 1 3 20 5 24 20.0 4.2 61.4 112 47 9.5 1.4 0.9 4.4 0.75 MA645.2LB 4 1 3 20 10 18 15.0 3.8 39.7 81 34 6.1 1.1 1.0 2.8 0.42 MA551.7LB 5 1 3 20 10 26 17.0 4.6 40.8 84 38 6.8 1.4 1.0 3.1 0.47 BOB27.5LB 7 1 3 20 10 24 19.0 4.6 66.5 128 51 8.2 1.7 1.2 3.3 0.53 BOB89.8LB 4 1 3 20 5 20 14.0 5.6 81.8 143 36 10.4 2.3 2.0 3.2 0.61 BOB1161LB 5 1 3 20 10 12 23.0 5.0 91.6 191 84 11.6 2.5 1.5 3.7 0.64 Average: 4.6 1.0 3.1 20.0 7.6 21.3 18.2 4.3 62.6 119.1 46.6 8.5 1.7 1.2 3.9 0.70 Standard dev.: 1.6 0.0 0.2 0.0 2.5 4.6 5.8 1.6 25.8 49.7 20.8 2.9 0.6 0.4 1.6 0.35

WLG58.0UB 7 1 3 20 10 12 8.9 2.3 19.9 39 18 2.9 0.7 0.5 1.8 0.32 MPI53.1UB 10 1 3 20 10 20 15.0 4.6 42.2 91 38 7.1 1.6 1.2 4.7 0.71 MPI54.0UB 7 1 3 20 10 20 17.0 5.4 45.5 96 48 8.1 1.3 1.3 4.1 0.67 MPU40.4UB 3 1 3 20 10 10 9.4 1.9 22.9 47 21 3.7 0.6 0.5 1.5 0.23 MPU117.3UB 6 1 3 20 10 16 11.0 3.4 24.1 53 29 5.1 1.0 0.6 2.7 0.43 MPU159.4UB 2 1 3 20 10 12 7.5 1.4 18.9 38 14 2.5 0.5 0.5 1.0 0.17 MPU183.8UB 3 1 3 20 10 14 6.9 1.4 18.6 37 14 3.3 0.6 0.5 1.3 0.23 MPU214.2UB 3 1 3 20 10 24 17.0 3.6 38.1 71 33 5.2 1.0 0.5 1.1 0.21 MPU241.5UB 6 1 3 20 10 16 11.0 4.1 30.2 63 30 4.6 1.1 0.6 2.0 0.34 MTR130.5UB 4 1 3 20 10 20 18.0 4.8 59.5 127 50 8.0 1.3 1.1 4.1 0.65 MTR159.5UB 4 1 3 20 10 26 21.0 5.5 82.0 161 55 9.0 1.8 1.2 3.6 0.56 MTR203.7UB 2 1 3 20 10 10 5.3 1.1 14.5 32 12 2.3 0.5 0.5 1.1 0.18 MA6I31.2UB 3 1 3 20 10 6 8.0 1.9 19.3 43 21 3.8 0.7 0.7 2.0 0.31 MA5114.1UB 7 1 3 20 5 24 15.0 4.9 33.8 67 29 5.5 0.6 0.7 4.1 0.80 MA5152.0UB 8 I 3 20 10 22 14.0 3.9 35.1 69 32 5.6 1.1 0.9 3.9 0.60 MA49.2UB 2 1 3 20 10 8 4.9 1.2 14.2 30 12 2.5 0.5 0.5 1.0 0.15 MA437.0UB 9 1 3 20 5 20 14.0 3.8 48.0 89 45 8.0 1.7 1.1 3.6 0.68 LPP28.0UB 10 1 3 20 10 24 15.0 4.2 43.2 92 43 7.4 1.6 1.1 5.2 0.79 LPP54.5UB 14 1 3 20 10 26 19.0 4.5 41.3 90 46 6.8 1.5 0.9 4.6 0.68 Average: 5.8 1.0 3.0 20.0 9.5 17.4 12.5 3.4 34.3 70.3 31.1 5.3 1.0 0.8 2.8 0.5 Standard dev.: 3.3 0.0 0.0 0.0 1.5 6.2 4.7 1.5 16.8 33.7 13.6 2.1 0.4 0.3 1.4 0.2 Entire Buckley Average: 5 2 1.0 3.0 20.0 8.6 19.2 15.2 3.8 47.6 93.3 38.4 6.9 1.4 1.0 3.3 0.6 Standard Dev. 2.7 0.0 0.2 0.0 2.2 5.9 6.0 1.6 25.8 48.6 19.0 3.0 0.6 0.4 1.6 0.3 303

7.0 2 std. dev. 6.0- M ean a i 2o 3 abundance, 5.0- 8 dolerite sills 4.0-

3.0-

2.0- > 1.0-

0.0 A1203 (normalized %) 7.0

6.0- Mean CaO abundance in dolerite sills = 10.7%

5.0-

u 4.0- w 5=(D £ 3.0- O 2.0-

1.0-

0.0 0.00.4 0.6 0.8 1.00.2 1.2 CaO (normalized %)

Section MKR -A - Section CPZ — Section M PI -e — Section MTR * Section TGA —i— Section MBO

Figure 62: Vitrinite reflectance vs. carbon-normalized abundances of representative major, trace and rare-earth elements. 304 Figure 62: continued.

7.0 2 std. dev. 6.0- Mean Na20 abundance, & dolerite sills 5.0- 8 § 4.0- G QC 3.0- 4> •g 2.0- 5 1 1.0-

0.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Na20 (normalized %)

7.0 2 std. dev. 6.0- Mean P2Os o abundance, cc dolerite sills 5.0-

u 4.0- u G

0.0 0.00 0.05 0.10 0.15 0.20 0.25 P205 (normalized %) Section MKR Section CPZ Section MP1 Section MTR Section TGA Section MBO Figure 62: continued.62: Figure

Vitrinite Reflectance (Ro) Vitrinite Reflectance (Ro) 0.0 0.0 2.0 3.0 6.0 2.0 3.0 4.0 5.0 4.0 1.0 6.0 7.0 5.0 7.0 1.0 . 02 . 06 . 10 1.2 1.0 0.8 0.6 0.4 0.2 0.0 20 0 60 0 10 10 10 10 1800 1600 1400 1200 1000 800 600 400 200 0 2 std. dev. std. — b — eto R — ScinTGA A G T —* Section — TR M Section eto R eto Z P C Section - A - KR M Section Mn (normalized ppm) (normalized Mn Ti02 (normalized (normalized Ti02 doleritesills abundance, 02Mean H V %) eie sills lerite o d abundance, abundance, MnO ean M Section MBO— Section — 2 std. dev. std. M PI PI M Figure 62: continued. 62: Figure

Vitrinite Reflectance (Ro) Vitrinite Reflectance (Ro) 0.0 2.0- 0.0 1.0- 2.0- 3.0- 4.0- 5.0- 6.0- 5.0- 1.0- 7.0 7.0 2 2 std. dev. std. std. dev. std. B- eto T ScinTA —•— Section TGA Section MBO Section MTR - -B Section MKR -A - Section CPZ - SectionMKR-A Zn (normalized ppm) (normalized Zn Sc (normalized ppm) (normalized Sc 100 120 - Section MPI 140 160 307 Figure 62: continued.

7.0 2 std. dev. 6.0 1 n 50 a 2 4 0. 8 40 G0 pg 3.0 4> 1 2.0 • Pt > 1.0

0.0- 4 6 8 lo" 12 Hf (normalized ppm)

7.0

2 std. dev. 6.0- o tC “ 5.0-

I 4.0-

•n 2.0- > 1.0-

0.0 Th (ppm)

Section MKR Ir- Section CPZ Section MPI Section MTR Section TGA Section MBO iue6: continued.62:Figure

Vitrinite Reflectance (Ro) Vitrinite Reflectance (Ro) 7.0 0.0 3.0- 0.0 2.0- 3.0- 4.0- 5.0- 6.0- 7.0 1.0- 1.0- 2 2 dev. std. std. dev. std. ScinMR Section TGA Section MTR - a - Section MKR Section -ak- CPZ La (normalized ppm) (normalized La Lu (normalized ppm) (normalized Lu Section — Section— MBO 0 120 100 MP1 309

22- ^ 20‘ •O 18- 8 10- < 0 2 std. dev.

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 Distance from Sill/Sill Thickness

1.0- Mean CaO abundance in dolerite sills = 10.7% 0.9

| 0.6 o S 0.5- S °'4' 0.3- 2 std. dev. 0.2- 0.1 Distance from Sill/Sill Thickness

• Section MKR -A - Section CPZ —*— Section MPI - B - Section MTR —* * - Section TGA —t— Section MBO

Figure 63: Carbon-normalized abundances of representative major, trace and rare- earth elements vs. proximity to intrusive bodies. 310

Figure 63: continued.

3.0

2.5- Mean N a20 $ abundance, ■g 2.0- dolerite sills .a "eo £ 1.5- eo O in- ^ 10 2 0.5- I 2 std. dev.

0.0 Distance from Sill/Sill Thickness

0.25

0.20

■8 £ 0.15- CO E oU4 3 o.io- uio Mean P205 CM abundance, Cl. dolerite sills 0.05-

0.00 Distance from Sill/Sill Thickness Section MKR - A - Section CPZ —*#- Section MPI —B— Section M l'R * Section TGA h — Section MBO 311

Figure 63: continued.

1800 1600- Mean MnO 1400- abundance, dolerite sills •o 1200- 1000- g 800- O 600- c 5 2 std. dev. 400-

Distance from Sill/Sill Thickness

1.2

1.0-

-o 0.8- Nu 0.6-1 Mean Ti02 abundance, S 0.4- dolerite sills P 0.2- 2 std. dev.

0.0 Distance from Sill/Sill Thickness • - Section MKR -A - Section CPZ Section MPI -B - Section MTR — Section TGA —<— Section MBO 312 Figure 63: continued.

25.0

20.0 S' CLa. •an) 15.0- JS *3 I 10.0- C $ 2 std. dev. 5.0-

0.0 Distance from Sill/Sill Thickness

160

140-

^ 120- Cu £ 100 v .H a 80-

g 60-

B N 40-

20-

Distance from Sill/Sill Thickness Section MKR -A - Section CPZ — Section MP1 □ Section MTR - x - Section TGA —i— Section MBO 313

Figure 63: continued.

10-

s x 12 std. dev.

Distance from Sill/Sill Thickness

35-

E 30 Q.CL | 25-

E 20- §

£ 1 5 ’ 10- 2 std. dev.

Distance from Sill/Sill Thickness

Section MKR Section CPZ Section MPI Section M I R Section TGA Section MBO 314

Figure 63: continued.

110 100- 90- 1 80- o. T3 70- .M ce 60" § 50- c

2 4 0 ' 30- 20-

Distance from Sill/Sill Thickness

0.90

0.80-

E 0.70- a.CL ^ 0.60- 73 I 0.50- co 3 0.40-

0.30- 2 std. dev.

0.20 Distance from Sill/Sill Thickness

Section MKR Section CPZ Section MPI Section MTR Section TGA Section MBO 315

25-

CS 20- 0 !A '• A V + ^v' + 5?*0 . - x 0 £ 15- A A iA^jpdr ^ s CT) 0 +*- □ 0 o 0 0 % IO­ 0 % I 2 std. dev. 0 0

0"l------1----1---1 I I I I I ------I 1-1—I I I I I II------1-----1—I M ID I ---- 1 1—I II I I I 0.01 0.10 1.00 10.00 100.00 Total Organic Carbon (%)

3.0

2.5- 2 std. dev.

2.0-

1.0-

h 0 0.5-

0.0 0.10 1.00 10.00 100.00 Total Organic Carbon (%) A Pagoda + Mackellar □ Fairchild * lower Buckley 0 upper Buckley

Figure 64: Abundances of representative major, trace and rare-earth elements vs. organic carbon content (note that elemental abundances are not carbon- normalized for this series of bivariate plots). 316 Figure 64: continued.

2.5-j l 2 std. dev.

2.0

O 1.5- CO □ U X 1.0- + X++ A h + f e 0 A 4k + A ++ 0 X 0.5- HHeh +x X □ 0 S'rH0 +x xx s 0 0 0.0 1 I I 1'T'I-- I I ±, I I I I I II I I I I 1 I M I T---1—I III!! 0.01 0.10 1.00 10.00 100.00 Total Organic Carbon (%)

1.0-

2 std. dev. 0.8-

£ °-6' O 2 0.4-1

cP 0 □ x - B & x X * * h x 0 a 0. —i—i—n i i m----- 1—i—i i i i i 11 B i i—i m b11 ii i—i—i Mini 0.01 0.10 1.00 10.00 100.00 Total Organic Carbon (%)

A Pagoda + Mackellar n Fairchild x lower Buckley b upper Buckley iue 4 continued. 64: Figure

MgO (%) Fe203 (% ) 0.0 0.5- 2.0- 3.0 10- 0.01 0.01 i 2 std.dev. Pgd + akla □ Fairchild □ Mackellar + Pagoda A x lower Buckley a upper Buckley upper a Buckley lower x 0.10 A Total O rganic C arbon arbon C rganic O Total T otal O rganic C arbon arbon C rganic O otal T + % a

+ +n xx 1.00 1.00 >E X (%) (%) 10.00 10.00 2 std.dev. • X x 100.00 100.00 317 318 Figure 64: continued.

1600-

1400- 2 std. dev.

1200-

E - a, 1000 Q. 800- O c □ 600- + + «+% a s ■r*- 400- + "*■ Q 200- X O B E x , 0 - 1------1----- 1— i r u m 1---- 1— I I I l I I T 1-- - - - 1— I I I l 111------1---- 1— I i‘ f I 111 0.01 0.10 1.00 10.00 100.00 Total Organic Carbon (%)

+ XBt- 0.80-

o 0.60-

2 std. dev.

1— i—i m m ------1— i—i it m i i i—i i i i r i t 0.01 0.10 1.00 10.00 100.00 Total Organic Carbon (%) A Pagoda + Mackellar ° Fairchild x lower Buckley h upper Buckley 319

Figure 64: continued.

14

2 std. dev. | 12- Q- 10- A e n 0 -t+ 0 B D- 8- A A + □ a- b C. e + A A P x a x 0 6- A -tx + + + xx+ + □ x 0 0 + A ++ +-H-+ x x< 4 + + ® A + + ■ » + x A + + + 00 x 00 0 2-j A + 0 r ^ i x

0- — i— i—i ini®------1— i—i i i i u i------1— i—i r i 11 n ------1— i— i i r m 0.01 0.10 1.00 10.00 100.00 Total Organic Carbon (%)

40 35 2 std. dev. i + 30 A + + S' 25 + -H- + CL, X . _ ,xF O? 20H HC + ' X"+ , X 0< P 15 0 10- 5-

0 I I I I' I I I I 11 I I I II 1 I I I I I I—I T l I 11 " 1 1—I I II I I 0.01 0.10 1.00 10.00 100.00 Total Organic Carbon (%)

A Pagoda + Mackellar □ Fairchild x lower Buckley h upper Buckley 320

Figure 64: continued.

110 100 90 80- E 70- + + + CL + -hD x CL 60- + P EAl1^ X £ A * 50- £ + +□ % + a a 40 a 1- a a a x 30- x I 2 std. dev. a a 20- a a 10 - 1— i—i r i 1111------1— i—i i i m i ------1— i—r r r i in ------1— i—i m n 1 0.01 0.10 1.00 10.00 100.00 Total Organic Carbon (%)

1.80 1.60- 1.40- 1 2 std. dev. 1.20 E Cl 1.00 - a a 0.80- a a s a X -J a @x X X 0.60- + * ,++ X X □+ a x 0.40- i xa a 0 0 a a 0.20- a a a 0 .0 0 "t ' i i i i 1111 i i i i i 1111 i i i mini r i i i r i m 0.01 0.10 1.00 10.00 100.00 Total Organic Carbon (%) ▲ Pagoda + Mackellar □ Fairchild x lower Buckley upper Buckley 321

30- 2 std. dev.

25- □ x s 20- o. t r i5- -Q c/3 10-

0.10 1.00 10.00 100.00 Total Organic Carbon (%)

2 std. dev. |

E 20;

10 20 30 40 50 6( Total Organic Carbon (%)

▲ Pagoda + Mackellar □ Fairchild x lower Buckley b upper Buckley

Figure 65: Transition metal abundances vs. organic carbon content, with detailed analysis of the Buckley Formation. 322

Figure 65: continued.

400 350- 300- /—s 250- 6 ex a 200- > 150- 100- 50-

0.01 0.10 1.00 10.00 100.00 Total Organic Carbon (%)

2 std. dev.

a. 200-j

10 20 30 40 50 Total Organic Carbon (%) ▲ Pagoda + Mackeliar □ Fairchild x lower Buckley h upper Buckley Figure 65: continued.65: Figure

Cr (ppm) Cr (ppm) 400 600- 200 300H 500- 700 400 400 200 300 500 600 700 100 100 100 0.01 0 0

1 2 3 4 5 60 50 40 30 20 10 0

2 std. dev. 2std. 1 i—i — x x x Pgd + akla a Fairchild a Mackellar + Pagoda ▲ x lower Buckley &> upper Buckley upper &> Buckley lower x rrirn rrirn E)B 0.10 Total Organic Carbon Carbon Organic Total oa rai abn( ) (% Carbon Organic Total * E F. E g*3 , ^ B a B H B 0

1 — i i i i—i — 11 h ^X X X x B X X ^ §hx x 1.00 n1 —ii m r r i i—i 1— “ 1n

X X X X X (%) 10.00 E

1 n r — t.dv | dev. 2 std. i 1111 100.00 1 324

Figure 65: continued.

2 std. dev.

10 20 30 40 50 Total Organic Carbon (%)

60

2 std. dev. 50-

^ 40- £ 3 30- o U 20-

' r a - 10-

0.01 0.10 1.00 10.00 100.00 Total Organic Carbon (%) ▲ Pagoda + Mackellar □ Fairchild x lower Buckley s upper Buckley Figure continued. 65:

Cu (ppm) Cu (ppm) 3 0 ' a. + A B + -N tn tn -N + B A + a. 20 ' 0 3 | 2sd e. ^ x x dev. std. 2 I _| 0 8 60- 9(h 0 ▲ Xx 0 ▲ 70H 0 1 + + + *+ + A 50-1 * 1 + * * ♦ ♦ * * + 1 * 10-1 .01 n a b s H a on

—i i nil n i i i i— i— — A lwrBcly a upper Buckley

+ + -Hr + + —i i f? f t t i i i i— 1— * * 1.00 ------

s

—i in i i m r i— 1— □ x X (%) 10.00 ------x

2 std. dev —i i i— 1— x Mini 100.00 326

Figure 65: continued.

300 2 std. dev. 250-

^ 200 - £ Cl 3 150-

N 100-

50-

0.01 0.10 1.00 10.00 100.00 Total Organic Carbon (%)

2 std. dev.

£ CL a. c N

10 20 30 40 50 Total Organic Carbon (%) A Pagoda + Mackellar a Fairchild x lower Buckley ® upper Buckley 327

2 sid. dev.'

T3 4> N 73 E o*-< c O 6 0 s

50 55 60 65 70 75 80 85 90 Si02 (normalized %)

2 std. dev.

$ T3

50 55 60 65 70 75 80 85 90 Si02 (normalized %)

A Pagoda + Mackellar □ Fairchild x lower Buckley ® upper Buckley F = mean tuff composition from the Falla Formation (Barrett and others, 1986)

Figure 66: Carbon-normalized abundances of representative major, trace and rare- earth elements vs. normalized Si02 content. Figure continued. 66: ma tuffmeancompositionfrom the Falla Formation - F (Barrett and others, 1986)

K20 (normalized %) Ca° (normalized %) 10.0 .- * a x 0.0"t 2.0- . E x + ¥ x E A+H* D^ x 3.0- 4.0- -°- 5 6.0 2.0 4.0 8 0.0 .- * 0 7.0- 6.0 9.0 3.0 5.0 7.0 8.0 -' 2 std. dev.1 x 1-0' 1.0 .0- 0 5 0 5 0 5 0 5 90 85 80 75 70 65 60 55 50 0 5 0 5 0 5 0 5 90 85 80 75 70 65 60 55 50

1 ------Pgd + akla □ Fairchild □ Mackellar + Pagoda ▲ x lower Buckley ® upper Buckley upper ® Buckley lower x 1 ------B + 4 + 4 > + + XX a i _ x + a 1 ------4 B +4+ x¥ 4E++Z* Si02 (normalized %) (normalized Si02 Si02 (normalized %) (normalized Si02 4* X a 1 ------P * >P 1 ------1 ------x X X 1 1 I ------2 std. dev.' 1 ------329

Figure 66: continued.

1.2 2 std. dev. ^ i.o-

1 08 ■« £ 0.6- o o 0.4- £ ^ + i -ft*" 1 ^ 0.2-

< 0 X X X 0.0

Si02 (normalized %)

300 2 std. dev. 1 250 6 £ 200 - •o % 150- BU £ 100‘ u (/> 50-

------1------1------1---- — I 65 70 75 8 Si02 (normalized %) ▲ Pagoda + Mackellar a Fairchild x lower Buckley M upper Buckley F = mean tuff composition from the Falla Formation (Bairett and others, 1986) 330 Figure 66: continued.

1800

1600- 2 std. dev. g, 1400- a , *o 1 2 0 0 -

1000 - 800- 600- 400- 200-

50 Si02 (normalized %)

300

2 std. dev. ^ 250 B CL & 2 0 0 .X X "O a> N ^ 150 i 100 g u X El A x x * $

°50 55 60 65 70 75 80 85 90 Si02 (normalized %) A Pagoda + Mackellar D Fairchild x lower Buckley » upper Buckley F = mean tuff composition from the Falla Formation (Barrett and others, 1986) 331

Figure 66: continued.

70- 2 std. dev. i

fX Cl, ■o 50-

40-

20 □

10-

T

Si02 (normalized %)

700-

600-1 2stddevJ

'b a. 500-j & •o .§ 400-1 "w 300-1 o & 2 0 0 J3 100-1

04 ...... 50 55 60 65 70 75 80 85 90 Si02 (normalized %) A Pagoda + Mackellar □ Fairchild x lower Buckley a upper Buckley iue 6 continued. 66: Figure

Lu (normalized ppm) 20- 25- 10 15- Pgd + akla ° Fairchild ° Mackellar + Pagoda ▲ x lower Buckley 3 upper Buckley upper 3 Buckley lower x Si02 (normalized (normalized Si02 %) 2 std. dev.* iue 7 Cro-omlzd bnacs frpeettv mjr tae n rare- and trace major, representative of abundances Carbon-normalized 67: Figure =ma tf opsto fo te al omto (art n ohr, 1986) others, and (Barrett Formation Falla the from composition tuff mean = F CaO (normalized %) Ti02 (normalized %) at eeet v. omlzd A120 3content. normalized vs. elements earth 2.50 0.00 0.50H 2.00 1.00 1.50 2 std. dev. 2 std. dev.' Pgd + akla n Fairchild n Mackellar + Pagoda A x lower Buckley a upper Buckley upper a Buckley lower x 0 5 0 25 20 15 10 a a A1203 (normalized %) (normalized A1203 %) (normalized A1203 5 0 5 0 35 30 25 20 15 0 X 0 x

30 333

334

Figure 67: continued.

7.0- X S * 6.0- X T3 c rU ,N 5.0- A + 13 73 Et-4 4.0 n O e 3.0-1 s -txx X x x t * 2 .0 13

1.0 2 std. dev,' 0.04 To” 15 20 25 30 35 A1203 (normalized %)

1.2 2 std. dev. 1

0 .0 ~ ~ r~ T 15 A1203 (normalized %) ▲ Pagoda + Mackellar a Fairchild x lower Buckley

Figure 67: continued.

300 2 std. dev. '

/ - s 2 5 0 ‘ 'b a 200- T3

73 150-

1 0 0 u C /3 50-

15 20 25 30 A1203 (normalized %)

1800 2 std. dev. 1600 E CL 1400- Q. TD 1200-

Figure 67: continued.

300 2 std. dev. 250-

150- + U x x -tf. -m-k T h4+ + x x a 100-

50-

A1203 (normalized %)

22 20 2 std. dev. ? 18 a is ■g 14 N ^ 12 9 A a D® X I 10 + + H a- +x + x x w 8 -FJfc + \ X 6 X + Hit- H+S X X x x X + + *-XH- + 4 ® X ^ v Xx X + ^J- H 2 ______10 15 20 25 30 35 A1203 (normalized %) ▲ Pagoda + Mackellar n Fairchild x lower Buckley ® upper Buckley iue 7 continued. 67:Figure

La (normalized ppm) Th (norma|ized ppm) 200- 400- 300- 500- 600 100 700 50 20 20 30 40 60 70 80 10 10 0

- 1 1 2 2 3 35 30 25 20 15 10 5 % dv i dev. d t s 2 Pgd + akla □ Fairchild □ Mackellar + Pagoda A x lower Buckley a upper Buckley upper a Buckley lower x X i i 203 nr lzd%) % alized (norm 3 0 I2 A 10 nr lzd ) % alized (norm A1203 ------f ^ X ^ -fc A X 1 ------1 ------X 2 std. dev. i r X 337 338 Figure 67: continued.

30 2 std. dev. 25- £ CL. cx 20- ■o

0-pB is xx 10 15 20 25 30 35 A1203 (normalized %) ▲ Pagoda + Mackellar a Fairchild x lower Buckley upper Buckley 339 2.50 2 std. dev. ST 2-°°- ■o u £ 1.50-

J , 1-00- CNo 0.50-

0.00 Fe203 (normalized %)

9.0-J 2 std. dev. 8.0 & TJ 7.0 1> N 6.0 5.0 O 4.0 O 3.0 09 u 2.0 >?< 1.0H 0.0 0 2 4 6 8 10 12 14 Fe203 (normalized %) ▲ Pagoda + Mackellar □ Fairchild x lower Buckley a upper Buckley F = mean tuff composition from the Falla Formation (Barrett and others, 1936)

Figure 68: Carbon-normalized abundances of representative major, trace and rare- earth elements vs. normalized FejOj content. 340 Figure 68: continued.

8-0~i

7.0-

J? 6.0- IS

1 5.0^ IS IS CO is a x ++ + ++ g 4.0 X r®^. +■£■ + +* o * X y f X 3 3.0-| X * O X ® X

1.0 2 std. dev.' o.o- 4 6 8 10 12 14 Fe203 (normalized %)

2 std. dev.1 ^ 1.0-1 $ | 0.8-| "c3 g 0.6-1 O »no 0.4- F D + + ± ++ + ±+ A 0.2 i s IS ^ “ ® +i++++D *A H # X 0 .0 0 4 6 8 10 12 142 Fe203 (normalized %) ▲ Pagoda + Mackellar D Fairchild x lower Buckley ® upper Buckley F = mean tuff composition from the Falla Formation (Barrett and others, 1986) 341

Figure 68: continued.

300 2 std. dev. 250 eT & 200 1) N *■9 150

B 100- u C/3 50- a * H la H «A A 0 0 4 "6 8 10 12 14 Fe203 (normalized %)

1800 1600- 2 std. dev. 1400-1 I 120CW #N 1000 "c3 a l-lE 800 o □ 600- E a x + ,*r + O E □ c 400- s X +A X X ■»* ef % * + 200 -

0 — r ~ —r~ 0 2 4 6 8 10 12 14 Fe203 (normalized %) A Pagoda + Mackellar a Fairchild x lower Buckley ® upper Buckley F = mean tuff composition from the Falla Formation (Barrett and others, 1986) 342

Figure 68: continued.

300 2 std. dev. ^ 250- E Q, 200 - t3 4> N ’■§ 150- E

Xx

Fe203 (normalized %)

20 -

? 18 & 16-

n + a x

* + + + + + ■fe-fcA + + + 13 + ++• aho Q

Fe203 (normalized %)

A Pagoda + Mackeltar □ Fairchild x lower Buckley a upper Buckley Figure continued.68:

La (normalized ppm) Th (normalized ppm) 200 400 300 600- 500- 100 60- 20 40- 50- 70- 30- 10 0 - - * ^ - - Pgd + akla a Fairchild a Mackellar + Pagoda A lwrBcly upper Buckley ® lower Buckley x Fe203 (normalized (normalized Fe203 Fe203 (normalized (normalized Fe203 "5r +v %) %) 2 std. dev. i 2 std. dev. 1 12 140 10 8 6 4 2 343 344 Figure 68: continued.

2 std. dev. _ 25-1 £ a a 20- •a a> N *e3e J , io h 3 -J 5H

□ 0 2 4 6 8 10 12 14 Fe203 (normalized %) Pagoda + Mackellar a Fairchild lower Buckley a upper Buckley APPENDIX C

MINERALOGIC ANALYSES BY X-RAY DIFFRACTOMETRY

BEARDMORE GLACIER REGION, ANTARCTICA

345 346

Table 18: Raw data from semi-quantitative x-ray diffraction analysis of Permian mudrocks from the Beardmore Glacier region, Antarctica.

SamplelD Phyllosilicate and Silicate Peak Areas Mineral peak examined Illite Cblorite Quartz Plagiocla.se All Feldspar K-Feldspar (in degrees 20) 8.9 12.50 20.85 22.05 23.5-23.8 26.9-27.10 PAGODA CPZ16.3LP 3.3 7.5 7.5 0.5 0.9 0.2 MTM129.0LP 5.8 7.8 8.7 1.5 0.8 0.8 TGA41.0LPrep. 1 0.7 1.8 14.5 1.0 1.2 0.0 TGA41.0LPrep. 2 1.4 1.7 13.0 1.4 0.8 1.5 TGA41.0LPrep. 3 1.6 1.0 19.2 0.9 0.6 1.7 TGA41.0 mean 1.2 1.5 15.6 1.1 0.9 1.1 Mean: 3.4 5.6 10.6 1.0 0.9 0.7 Standard dev.: 1.9 2.9 3.6 0.4 0.0 0.4

MMP74.5UP 1.9 0,6 4.9 1.6 2.5 2.8 MTM186.2UP 2.9 5.0 13.2 2.9 1.1 0.6 TGA96.7UP 2.1 5.8 13.5 1.3 1.1 0.0 Mean: 2.3 3.8 10.5 1.9 1.6 1.1 Standard dev.: 0.4 2.3 4.0 0.7 0.7 1.2 Entire Pagoda Mean: 2.9 4.7 10.6 1.5 1.2 0.9 Standard dev.: 1.5 2.8 3.8 0.7 0.6 0.9 MACKELLAR MKR6.0LM rep. 1 11.9 12.7 7.1 1.5 1.1 0.0 MKR6.0LM rep. 2 15.5 10.2 8.5 1.5 0.4 0.0 MKR6.0LM rep. 3 11.8 11.5 7.2 1.0 0.6 0.0 MKR6.0LM rep. 4 12.7 12.1 7.1 1.1 1.1 0.0 MKR6.0LM rep. 5 14.3 12.3 8.3 0.8 0.9 0.0 MKR6.0 mean 13.2 11.8 7.6 1.2 0.8 0.0 MMC20.5LM 2.7 5.7 8.5 0.0 0.5 1.5 CPZ123.4LM 6.6 10.1 9.5 1.0 1.8 0.0 TGA160.0LM 3.4 6.3 6.1 0.6 0.8 1.6 CHI132.6LM rep. 1 3.6 6.6 7.7 0.8 0.9 0.8 CHI132.6LM rep. 2 5.3 8.5 6.7 0.5 1.2 0.8 CHI 132.6 mean 4.5 7.6 7.2 0.7 1.1 0.8 MDK20.5LM 4.7 1.8 7.7 2.2 2.0 0.0 Mean: 5.8 7.2 7.8 0.9 1.2 0.7 Standard dev.: 3.5 3.2 1.1 0.7 0.5 0.7

MMQ4.3MM 6.8 11.0 6.9 1.2 1.0 0.0 MMC49.1MM 7.3 13.6 10.8 1.2 0.9 0.0 MMD1 l.OMM 4.4 7.3 6.3 0.0 0.0 1.7 MMD27.0MM 4.1 7.4 10.4 1.6 1.7 1.5 TRM27.5MM rep. 1 11.2 16.3 11.1 0.7 1.6 0.0 TRM27.5MM rep. 2 9.4 10.2 9.8 0.7 0.7 1.1 347 Table 18: continued.

SamplelD Phyllosilicate and Silicate Peak Areas Mineral peak examined Illile Chlorite Quartz Plagioclase All Feldspar K-Feldspar (in degrees 20) 8.9 12.50 20.85 22.05 23.5-23.8 26.9-27.10 TRM27.5 mean 10.3 13.3 10.5 0.7 1.2 0.6 CPZ145.9MM 11.5 14.1 7.0 0.5 1.6 0.5 TGA173.0MM 11.7 3.3 10.2 1.0 0.9 0.5 MB067.8MM 0.7 3.6 5.0 2.5 3.8 2.1 CHI178.5MM 3.8 4.1 6.3 0.5 0.5 0.0 Mean: 6.7 8.6 8.2 1.0 1.3 0.8 Standard dev.: 3.6 4.2 2.1 0.7 1.0 0.8

MKR58.5UM 5.7 4,9 9.6 0.6 0.6 0.0 MMC117.5UM 5.6 8.3 10.4 1.7 1.7 1.0 MMD115.5UM rep. 1 5.5 7.9 6.6 1.0 0.5 0.2 MMD115.5UM rep. 2 4.7 7.1 6.0 0.4 0.5 0.0 MMD115.5 mean 5.1 7.5 6.3 0.7 0.5 0.1 CPZ176.1UM 6.4 7.7 11.4 1.2 1.0 0.0 MTM269.0UM rep. 1 7.7 12.4 7.8 0.7 0.3 0.0 MTM269.0UM rep. 2 8.1 13.1 8.1 0.6 0.3 0.0 MTM269.0 mean 7.9 12.8 8.0 0.7 0.3 0.0 MBO88.0UM 1.7 3.5 6.4 1.7 1.6 1.1 MBO125.0UM 0.7 4.2 10.6 4.4 5.4 2.9 MDKI19.0UM 1.9 8.0 10.2 0.6 1.0 1.6 Mean: 4.4 7.1 9.1 1.4 1.5 0.8 Standard dev.: 2.4 2.8 1.8 1.2 1.5 1.0 Entire Mackellar Mean: 5.7 7.7 8.4 1.1 1.3 0.8 Standard dev.: 3.4 3.6 1.9 0.9 1.2 0.8 FAIRCHILD MKR90.5LF 6.0 11.6 7.1 0.6 0.8 0.7 TGF136.0F 4.3 6.1 8.4 1.9 1.4 0.0 M B0170.0UF 1.2 7.6 5.7 0.9 2.6 3.5 MDK209.0F? rep. 1 4.0 4.6 7.5 2.2 2.9 0.0 MDK209.0F? rep. 2 4.3 5.7 11.0 2.0 2.3 0.6 MDK209.0 mean 4.2 5.2 9.3 2.1 2.6 0.3 Entire Fairchild Mean: 3.9 7.6 7.6 1.4 1,9 1.1 Standard dev.: 1.7 2.5 1.3 0.6 0.8 1.4 BUCKLEY MMD283.5LB rep. 1 2.8 12.7 4.5 0.3 1.3 1.0 MMD283.5LB rep. 2 2.8 10.7 5.9 0.0 1.7 0.9 MMD283.5 mean 2.8 11.7 5.2 0.2 1.5 1.0 MMD440.5LB rep. 1 0.8 0.8 6.7 0.5 0.8 0.5 MMD440.5LB rep. 2 0.7 0-7 6.6 0.0 0.4 1.0 348

Table 18: continued. SamplelD Phyllosilicate and Silicate Peak Areas Mineral peak examined Illite Chlorite Quartz Plagioclase All Feldspar K-Feldspar (in degrees 20) 8.9 12.50 20.85 22.05 23.5-23.8 26.9-27.10 MMD440.5 mean 0.8 0.8 6.7 0.3 0.6 0.8 TGF218.0LB 7.0 12.7 6.5 2.1 0.8 0.6 MPI28.6LB 2.1 4.5 11.4 2.6 1.7 0.0 MA645.2LB 6.0 0.9 14.7 1.0 0.9 2.1 BOB27.5LB 2.4 7.8 8.7 0.5 1.8 0.8 BOB116.1LB 0.5 11.9 4.6 0.5 0.7 2.4 Mean: 3.1 7.2 8.3 1.0 1.1 1.1 Standard dev.: 2.3 4.8 3.4 0.9 0.5 0.8

WLG5.0UB 0.8 4.7 11.5 1.9 1.6 0.0 MPI54.0UB 1.3 0.4 5.4 0.1 0.9 0.8 MPU117.3UB 1.2 0.0 17.9 0.7 6.6 5.0 MPU241.5UB rep. 1 1.8 0.0 9.8 3.2 1.2 0.0 MPU241.5UB rep. 2 3.4 0.0 10.0 2.4 1.3 0.7 MPU241.S mean 2.6 0.0 9.9 2.8 1.3 0.4 MTR13.1UB 3.9 0.0 4.5 0.4 0.4 0.0 MTR61.1UB 1.7 2.7 6.3 1.9 0.4 1.0 MTR159.5UB o.o 0.0 9.1 0.4 3.9 2.7 MA5114.1UB 1.7 0.5 9.9 1.2 0.4 0.0 MA437.0UB 0.6 0.0 8.1 5.3 1.7 1.7 LPP54.5UB rep. 1 0.0 0.0 8.4 0.0 2.1 3.5 LPP54.5UB rep. 2 0.0 0.0 7.9 0.0 2.0 1.4 LPP54.5 mean 0.0 0.0 8.2 0.0 2.1 2.5 Mean: 1.4 0.8 9.1 1.5 1.9 1.4 Standard dev.: 1.1 1.5 3.6 1.5 1.9 1.5 Entire Buckley Mean: 2.1 3.4 8.7 1.3 1.6 1.3 Standard dev.: 1.9 4.5 3.5 1.3 1.5 1.3 349 Table 18: continued.

SamplelD Other Peak Area Illite Vitrinite Mineral peak examined Microcline Plagioclase Clay Boehmite Peak width Reflectance (in degrees 20) 27.52 27.79-28.05 14.49 (Ro) PAGODA CPZ16.3LP 0.5 0.9 4.0 0.75 MTM129.0LP 3.7 19.0 4.7 0.36 2.81 TGA41.0LPrep. 1 2.2 9.7 4.1 0.15 TGA41.0LPrep. 2 2.3 8.5 5.1 0.19 TGA41.0LP rep. 3 2.8 9.0 5.0 0.30 TGA41.0 mean 2.4 9.1 4.7 0.21 3.40 Mean: 2.2 9.7 4.5 0.44 Standard dev.: 1.3 7.4 0.3 0.23

MMP74.5UP 1.5 0.7 1.4 0.24 Barren MTM186.2UP 1.0 12.1 3.7 0.32 3.18 TGA96.7UP 2.2 14.3 4.2 0.36 3.07 Mean: 1.6 9.0 3.1 0.31 Standard dev.: 0.5 6.0 1.2 0.05 Entire Pagoda Mean: 1.9 9.3 3.8 0 3 7 Standard dev.: 1.0 6.7 1.1 0.18 MACKELLAR MKR6.0LM rep. 1 1.7 12.0 4.9 0.29 MKR6.0LM rep. 2 0.4 11.4 3.1 0.36 MKR6.0LM rep. 3 0.0 12.0 4.3 0.33 MKR6.0LM rep. 4 0.4 10.5 5.7 0.31 MKR6.0LM rep. 5 0.8 10.7 5.0 0.33 MKR6.0 mean 0.7 11.3 4.6 0.32 0.78 MMC20.5LM 0.5 2.3 6.1 0.32 CPZ123.4LM 0.7 13.9 1.7 0.40 3.10 TGA160.0LM 1.5 6.8 3.8 0.37 CHI132.6LM rep. 1 6.4 4.8 1.6 0.33 CHI132.6LM rep. 2 1.1 5.4 2.6 0.37 CHI 132.6 mean 3.8 5.1 2.1 0.35 3.92 MDK20.5LM 0.5 18.9 4.5 0.39 5.44 Mean: 1.3 9.7 3.8 0.36 Standard dev.: 1.2 5.6 1.5 0.03

MMQ4.3MM 0.0 10.4 7.0 0.38 2.38 MMC49.1MM 0.9 9.9 5.3 0.33 2.84 MMD11.0MM 2.1 10.2 5.4 0.38 2.02 MMD27.0MM 0.0 10.8 5.8 0.31 1.93 TRM27.5MM rep. 1 0.7 11.5 5.3 0.37 TRM27.5MM rep. 2 0.3 10.5 4.0 0.20 350 Table 18: continued.

SamplelD Other Peak Area Illite Vitrinite Mineral peak examined Microcline Plagioclase Clay Boehmite Peak width Reflectance (in degrees 20) 27.52 27.79-28.05 14.49 (Ro) TRM27.5 mean 0.5 11.0 4.7 0.29 1.37 CPZ145.9MM 1.0 11.0 2.7 0.39 2.64 TGA173.0MM 1.0 13.4 3.9 0.41 3.70 MB067.8MM 1.9 17.5 4.4 0.08 3.21 CHI178.5MM 0.6 4.7 3.8 0.36 2.24 Mean: 0.9 11.0 4.8 0.32 Standard dev.: 0.7 3.2 1.2 0.10

MKR58.5UM 0.6 6.6 3.2 0.32 1.26 MMC117.5UM 0.4 9.2 2.3 0.36 3.00 MMD115.5UM rep. 1 0.7 4.7 3.4 0.42 MMD115.5UM rep. 2 0.9 4.6 3.1 0.37 MMD115.5 mean 0.8 4.7 3.3 0.40 2.11 CPZ176.1UM 2.1 13.5 3.5 0.34 2.78 MTM269.0UM rep. 1 0.3 4.6 4.8 0.35 MTM269.0UM rep. 2 0.7 7.8 2.7 0.37 MTM269.0 mean 0.5 6.2 3.8 0.36 2.99 MBO88.0UM 3.6 11.0 3.1 0.26 2.86 MBO125.0UM 4.0 22.5 2.6 0.20 1.71 MDK119.0UM 6.0 2.9 4.5 0.27 5.40 Mean: 2.3 9.6 3.3 0.31 Standard dev.: 1.9 5.8 0.6 0.06 Entire Mackellar Mean: 1.5 10.2 4.0 0.33 Standard dev.: 1.5 4.9 1.3 0.07 FAIRCHILD MKR90.5LF 0.2 6.0 4.3 0.45 TGF136.0F 2.0 8.0 3.0 0.44 Barren M B0170.0UF 4.6 7.8 3.3 0.40 2.23 MDK209.0F? rep. 1 0.8 14.8 3.5 0.31 MDK209.0F? rep. 2 1.4 15.6 3.2 0.37 MDK209.0 mean 1.1 15.2 3.4 0.34 4.81 Entire Fairchild Mean: 2.0 9.3 3.5 0.41 3.5 Standard dev.: 1.6 3.5 0.5 0.04 1.3 BUCKLEY MMD283.5LB rep. 1 2.6 1.4 kaolinite 3.6 0.32 MMD283.5LB rep. 2 3.6 2.2 kaolinite 3.5 0.28 MMD283.5 mean 3.1 1.8 3.6 0.30 0.93 MMD440.5LB rep. 1 0.4 1.1 6.5 0.00 MMD440.5LB rep. 2 0.7 2.1 5.8 0.00 351 Table 18: continued.

SamplelD Other Peak Area IUite Vitrinite Mineral peak examined Microcline Plagioclase Clay Boehmite Peak width Reflectance (in degrees 20) 27.52 27.79-28.05 14.49. (Ro> MMD440.5 mean 0.6 1.6 6.2 0.00 2.09 TGF218.0LB 0.1 12.2 3.7 0.50 Coked MPI28.6LB 0.7 15.1 3.6 0.37 6.23 MA645.2LB 0.2 5.9 4.9 0.36 2.42 BOB27.5LB 1.9 13.5 3.4 0.31 1.50 BOB116.1LB 5.2 12.8 3.5 0.21 1.32 Mean: 1.7 9.0 4.1 0.29 Standard dev.: 1.7 5.3 1.0 0.14

WLG5.0UB 0.0 10.8 4.9 0.26 2.34 MPI54.0UB 0.5 0.0 3.2 0.11 3.26 MPU117.3UB 5.5 0.0 3.8 0.00 3.15 MPU241.5UB rep. 1 0.1 18.6 4.5 0.23 MPU241.5UB rep. 2 0.2 18-1 3.7 0.31 MPU 241.5 mean 0.2 18.4 4.1 0.27 3.25 MTR13.1UB 0.0 0.1 3.9 0.23 4.36 MTR61.1UB 1.0 9.5 2.0 0.21 3.31 MTR159.5UB 5.5 2.1 5.0 0.00 2.41 MA5114.1UB 0.5 8.3 6.5 0.00 3.47 MA437.0UB 11.4 22.0 4.5 0.00 2.93 LPP54.5UB rep. 1 4.6 0.1 5.6 0.00 LPP54.5UB rep. 2 2.8 0.8 4.3 0.00 LPP54.5 mean 3.7 0.5 5.0 0.00 2.67 Mean: 2.8 7.2 4.3 0.11 Standard dev.: 3.5 7.7 1.1 0.12 Entire Buckley Mean: 2.4 7,9 4.2 0.18 Standard dev.: 3.0 6.9 | 1.1 0.16 352

Table 19: Complete results of relative mineral abundance calculations. Boehmite- normalized peak areas are listed for minerals that have a coefficient of variability less than 20%.

Sample ID Boehmite-Nonnalized Peak Areas lUite Chlorite Quartz All Feldspar Plagioclase to boehmite to boehmite to boehmite to boehmite to boehmite ratio ratio ratio ratio ratio PAGODA CPZ16.3LP 0.8 1.9 1.9 0.2 0.2 M TM129.0LP 1.2 1.7 1.9 0.2 4.0 TGA41.0LP 0.2 0.4 3.5 0.3 2.4 TGA41.0LP 0.3 0.3 2.5 0.2 1.7 TGA41.0LP 0.3 0.2 3.8 0.1 1.8 TGA 41.0 mean 0.3 0.3 3.3 0.2 1.9 Mean: 0.8 1.3 2.3 0.2 2.1 Standard dev.: 0.4 0.7 0.7 0.0 1.6

MMP74.5UP 1.4 0.4 3.5 1.8 0.5 M TM186.2UP 0.8 1.4 3.6 0.3 3.3 TGA96.7UP 0.5 1.4 3.2 0.3 3.4 Mean: 0.9 1.1 3.4 0.8 2.4 Standard dev.: 0.4 0.4 0.2 0.7 1.3 Entire Pagoda Mean: 0.8 1.2 2.9 0.5 2.2 Standard dev.: 0.4 0.6 0.7 0.6 1.5 MACKELLAR MKR6.0LM rep. 1 2.4 2.6 1.4 0.2 2.4 MKR6.0LM rep. 2 5.0 3.3 2.7 0.1 3.7 MKR6.0LM rep. 3 2.7 2.7 1.7 0.1 2.8 MKR6.0LM rep. 4 2.2 2.1 1.2 0.2 1.8 MKR6.0LM rep. 5 2.9 2.5 1.7 0.2 2.1 MKR6.0M mean 3.1 2.6 1.8 0.2 2.6 MMC20.5LM 0.4 0.9 1.4 0.1 0.4 CPZ123.4LM 3.9 5.9 5.6 1.1 8.2 TGA160.0LM 0.9 1.7 1.6 0.2 1.8 CHI132.6LM rep. 1 2.3 4.1 4.8 0.6 3.0 CHI132.6LM rep. 2 2.0 3.3 2.6 0.5 2.1 CHI132.6LM mean 2.1 3.7 3.7 0.5 2.5 MDK20.5LM 1.0 0.4 1.7 0.4 4.2 Mean: 1.9 2.5 2.6 0.4 3.3 Standard dev.: 1.2 1.9 1.5 0.3 2.5 353 Table 20: continued. Sample ID Boehmite-Normalized Peak Areas Ulite Chlorite Quartz All Feldspar Plagioclase to boehmite to boehmite to boehmite to boehmite to boehmite ratio ratio ratio ratio ratio MMQ4.3MM 1.0 1.6 1.0 0.1 1.5 MMC49.1MM 1.4 2.6 2.0 0.2 1.9 MMDU.OMM 0.8 1.4 1.2 0.0 1.9 MMD27.0MM 0.7 1.3 1.8 0.3 1.9 TRM27.5MM rep. 1 2.1 3.1 2.1 0.3 2.2 TRM27.5MM rep. 2 2.4 2.6 2.5 0.2 2.6 TRM27.5MM mean 2.2 2.8 2.3 0.2 2.4 CPZ145.9MM 4.3 5.2 2.6 0.6 4.1 TGA173.0MM 3.0 0.8 2.6 0.2 3.4 MB067.8MM 0.2 0.8 1.1 0.9 4.0 CHI178.5MM 1.0 1.1 1.7 0.1 1.2 Mean: 1.6 1.9 1.8 0.3 2.5 Standard dev.: 1.2 1.3 0.6 0.3 1.0

MKR58.5UM 1.8 1.5 3.0 0.2 2.1 MMC117.5UM 2.4 3.6 4.5 0.7 4.0 MMD115.5UM rep. 1 1.6 2.3 1.9 0.1 1.4 MMD115.5UM rep. 2 1.5 2.3 1.9 0.2 1.5 MMD115.5UM mean 1.6 2.3 1.9 0.2 1.4 CPZ176.1UM 1.8 2.2 3.3 0.3 3.9 MTM269.0UM rep. 1 1.6 2.6 1.6 0.1 1.0 MTM269.0UM rep. 2 3.0 4.9 3.0 0.1 2.9 MTM269.0UM mean 2.3 3.7 2.3 0.1 1.9 MBO88.0UM 0.5 1.1 2.1 0.5 3.5 MBO125.0UM 0.3 1.6 4.1 2.1 8.7 MDK119.0UM 0.4 1.8 2.3 0.2 0.6 Mean: 1.4 2.2 2.9 0.5 3.3 Standard dev.: 0.8 0.9 0.9 0.6 2.3 Entire Mackellar Mean: 1.6 2.2 2.4 0.4 3.0 Standard dev.: 1.1 1.4 1.1 0.4 2.0 FAIRCHILD MKR90.5LF 1.4 2.7 1.7 0.2 1.4 TGF136.0F 1.4 2.0 2.8 0.5 2.7 MB0170.0UF 0.4 2.3 1.7 0.8 2.4 MDK209.0F? rep. 1 1.1 1.3 2.1 0.8 4.2 MDK209.0F? rep. 2 1.3 1.8 3.4 0.7 4.9 MDK209.0F? mean 1.2 1,5 2.8 0.8 4.6 Entire Fairchild Mean: 1.1 2.1 2.2 0.6 2.7 Standard dev.: 0.4 0.4 0.6 0.2 1.1 354

Table 20: continued. Sample ID Boehmite-Normalized Peak Areas mite Chlorite Quartz All Feldspar Plagioclase to boehmite to boehmite to boehmite to boehmite to boehmite ratio ratio ratio ratio ratio BUCKLEY MMD283.5LB rep. 1 0.8 3.5 1.3 0.4 0.4 MMD283.5LB rep. 2 0.8 3.1 1.7 0.5 0.6 MMD283.5 mean 0.8 3.3 1.5 0.4 0.5 MMD440.5LB rep. 1 0.1 0.1 1.0 0.1 0.2 MMD440.5LB rep. 2 0.1 0.1 1.1 0.1 0.4 MMD440.5LB mean 0.1 0.1 1.1 0.1 0.3 TGF218.0LB 1.9 3.4 1.8 0.2 3.3 MPI28.6LB 0.6 1.3 3.2 0.5 4.2 MA645.2LB 1.2 0.2 3.0 0.2 1.2 BOB27.5LB 0.7 2.3 2.6 0.5 4.0 BOB116.1LB 0.1 3.4 1.3 0.2 3.7 Mean: 0.8 2.0 2.0 0.3 2.4 Standard dev.: 0.6 1.4 0.8 0.2 1.6

WLG5.0UB 0.2 1.0 2.3 0.3 2.2 MPI54.0UB 0.4 0.1 1.7 0.3 0.0 MPU117.3UB 0.3 0.0 4.7 1.7 0.0 MPU241.5UB rep. 1 0.4 0.0 2.2 0.3 4.1 MPU241.5UB rep. 2 0.9 0.0 2.7 0.4 4.9 MPU241.5UB mean 0.7 0.0 2.4 0.3 4.5 MTR13.1UB 1.0 0.0 1.2 0.1 0.0 MTR61.1UB 0.9 1.4 3.2 0.2 4.8 MTR159.5UB 0.0 0.0 1.8 0.8 0.4 MA5114.1UB 0.3 0.1 1.5 0.1 1.3 MA437.0UB 0.1 0.0 1.8 0.4 4.9 LPP54.5UB rep. 1 0.0 0.0 1.5 0.4 0.0 LPP54.5UB rep. 2 0.0 0.0 1.8 0.5 0.2 LPP54.5UB mean 0.0 0.0 1.7 0.4 0.1 Mean: 0.4 0.3 2.2 0.5 1.8 Standard dev.: 0.3 0.5 1.0 0.5 2.0 Entire Buckley Mean: 0.5 1.0 2.2 0.4 2.1 Standard Dev. \ 0.5 1.3 0.9 0.4 1.9