Sandstone, but the Proportion of Sandstone Increases to the Northwest
Total Page:16
File Type:pdf, Size:1020Kb
RF 2632 Institute of Polar Studies Report No. 34 STRATIGRAPHY AND PETROLOGY OF THE MAINLY FLUVIATILE PERMIAN AND TRIASSIC BEACON ROCKS, BEARDMORE GLACIER AREA, ANTARCTICA by Peter J. Barrett Institute of Polar Studies August, 1969 The Ohio State University Research Foundation GOLDTHWAIT POLAR LIBRARY Columbus, Ohio 43212 BYRO POLAR RESEARCH CENTER THE OHIO STATE UNIVERSITY 1090 CARMACK ROAD COLUMBUS, OHIO 43210 USA. INSTITUTE OF POLAR STUDIES Report No. 34 STRATIGRAPHY AND PETROLOGY OF THE MAINLY FLUVIATILE PERMIAN AND TRIASSIC BEACON ROCKS, BEARDMORE GLACIER AREA, ANTARCTICA by Peter J. Barrett Institute of Polar Studies The Ohio State University Columbus, Ohio August 1969 The Ohio State University Research Foundation Columbus, Ohio 43212 ERRATA Institute of Polar Studies Report 34 Peter J r Barrett "Strati ~ranhy and 0etrolo ~y of t he Mainly Flnviatile Permian and Triassic Tieacon Rocks, 1eardmore Glacier Area, Antarctica11 In modal analyses of sampl e s from the 3uckley , Fremouw, a ..1d Falla Formations (Table s 9, 13, and 15, respectively), t he per centa-;;e 11 11 in the R.8;ST catec;or;y should be reduced by the percenta.15e in the 11 PR/ZEOL' 1 category . Analyses for samples with more thm 20 percent calcite, prehnite, or z.eolite are correct as they stand., ABSTRACT The near horizontal Beacon strata (Devonian?-Triassic) of the Beardmore Glacier area rest on a peneplain cut mainly in a Precambrian to Lower Paleozoic graywacke and phyllite sequence intruded by granitic plutons. The 2600-m-thick Beacon sequence comprises eight formations; the Alexandra Formation (Devonian?), the Pagoda, Mackellar, Fairchild and Buckley Formations (Permian), the Fremouw and Falla Formations (Triassic), and the Triassic?-Jurassic Prebble Formation. The Ferrar Group (Jurassic), which overlies and intrudes the Beacon rocks, c~n prises the Kirkpatrick Basalt and Ferrar Dolerite. This study is con cerned mainly with the stratigraphy and petrology of the Permian and Triassic Beacon strata above the glacial Pagoda Formation. The Mackellar Formation, which conform.ably overlies the Pagoda Formation, consists of 60 to 140 m of laminated medium- to dark-gray shale and light-gray fine-grained sandstone, but the proportion of sandstone increases to the northwest. Current flow was southeasterly. The formation was deposited in a quiet body of water extending for 1000 km along the Transantarctic Mountains from the Queen Elizabeth Range to the Ohio Range; Sr87/Sr86 ratios suggest a noimlarine enviroimlent. The Fairchild Formation consists of 130 to 220 m Qf arkosic sand stone deposited by southeast-flowing streams. The sand was derived from a granitic and metasedimentary source, though same may have been reworked glacial debris. The Buckley Formation is a crudely cyclic coal-bearing sequence about 750 m thick; sandstone beds rest on erosion surfaces and grade upward into carbonaceous shale. Coal forms as much as six percent of the section. Leaves (mainly Glossopteris) and stems are carmnon. Buckley sandstone had two nonvolcanic sources; quartz - plagioclase - K-feldspar sand from the west, and quartz-plagioclase sancl. from the north. Intermediate-acid volcanic detritus appears 100-300 m above the base of the formation and dominates the sandstones in the upper part. The Triassic Fremouw Formation consists of three parts: the lowest is a 100-m-thick cyclic sequence of quartzose sandstone and greenish gray siltstone; the middle, 200 m thick, is mainly siltstone and in cludes sandstone with volcanic fragments; the upper 300 mis mainly similar volcanic sandstone, although the beds become carbonaceous toward the top. A labyrinthodont jawbone fragment was discovered near the base of the formation, and leaves of Dicroidium and logs were found near the top; root impressions occur throughout. The Falla Formation, which is from 160 to 530 m thick, is a cyclic sandstone-shale sequence in the lower part. The sandstone is more ii quartzose than that below, but it is diluted progressively up the sec tion by volcanic material. The upper part of the formation is dominated by vitric tuff. Accretionary lapilli suggest at least one volcanic center within the Queen Alexandra Range. The Fremouw and Falla Forma tions were deposited on a flood plain with streams flowing to the north west, in contrast to the southeast-flowing Permian streams. The Prebble Formation, from 0 to at least 460 m thick includes laharic deposits, agglomerate and tuff, and is overlain by Kirkpatrick Basalt. Several diabase sills, normally from 50 to 200 m thick, in trude the strata between the Pagoda and Falla Formations. Metamorphism by the sills has resulted, in the Buckley and Fremouw Formations, in locally extensive laumontite replacement of plagioclase, volcanic grains and matrix in the volcanic sandstones. Replacement minerals in the Falla and Prebble Formations include clinoptilolite, analcime and mordenite. A few sandstones in the Buckley and Fremouw Formations contain prehnite and grossularite. iii ACKNOWLEDG:MENTS The writer thanks R. J. Baillie, Dr. D. H. Elliot, D. Johnston, and Dr. J. F. Lindsay for their good company, and willing assistance in the field. The field work was carried out between November 16, 1966, and February 7, 1967, and between November 11, 1967, and February 2, 1968. Stratigraphic sections at Mount Miller and Mount Weeks (CO) were measured jointly with Dr. Lindsay. The support and cooperation of the Office of Antarctic Programs at the National Science Foundation, the U. S. Navy Task Force 43, and particularly the crews of the LC-130 Hercules aircra~ of Air Developnent Squadron Six are gratefully acknowledged. Financial support for the project was provided through National Science Foundation grants GA-534, GA-1159 and GA-1617 to The Ohio State University Research Foundation. This report is based on a Ph.D. dissertation (Barrett, 1968) supervised by Dr. Charles H. Summerson, and critically reviewed by Drs. D. H. Elliot, G. W. Moore, Jr., J.M. Schopf and C. H. Summerson. Discussions with the above, and with Dr. V. H. Minshew, now at the University of Mississippi, on various aspects of Beardmore geology are much appreciated. iv TABLE OF CONTENTS ABSTRACT ii ACKNOWLEDGMENTS iv INTRODUCTION l. PREVIOUS WORK l. STRATIGRAPHY AND PETROGRAPHY 5 Introductory Remarks 5 Stratigraphic Summary 6 Petrographic Methods 9 Modal. Analyses 9 Grain Size Analyses 13 Permian System l.3 Mackel.l.ar Formation l.3 Definition 13 Distribution and thickness l.3 Lower contact J.6 Lithology J.6 Petrography 17 Primary structures J.7 Pal.eontol.ogy 20 Correlation and age 20 Environment of deposition and source 22 Fairchild Formation 23 Definition 23 Distribution and thickness 23 Lower contact 25 Lithology 25 Petrography 27 Primary structures 27 Paleontology 3l. Correlation and age 31 Environment of' deposition and source 32 Buckley Formation 32 Definition 32 v TABLE OF CONTENTS - (continued) Distribution and thickness 33 Lower contact 33 Lithology 35 Petrography 37 Primary structures 43 Paleontology 45 Correlation and age 45 Environment of deposition and source 47 Triassic System 48 Frem.ouw Formation 48 Definition 48 Distribution and thickness 48 Lower contact 50 Lithology 5l Phosphate pebbles 54 Petrography 56 Metamorphism in the Fremouw and other formations 6l Primary structures 6l Paleontology 62 Correlation and age 64 Environment of deposition and source 66 Falla Formation 67 Background 67 Definition 67 Distribution and thickness 69 Lower contact 69 Lithology 69 Petrograpby 72 Primary structures 76 Paleontology 77 Correlation and age 77 Environment of deposition and source 78 Prebble Formation 78 Definition 78 Distribution and thickness 78 Lower contact 80 Lithology 80 Petrograpby 81 Primary structures 81 vi TABIE OF CONTENTS - (continued) ps~e Correlation and age Environment of deposition and source 84 Jurassic System - Ferrar Group 84 Ferrar Dolerite 84 Kirkpatrick Basalt 85 POST-PALEOZOIC FAULTING AND FOLDING 86 SUMMARY 91 APPENDIX I - SELECTED STRATIGRAPHIC SECTIONS 93 REFERENCES 127 vii LIST OF FIGUBES Figure No. l Ross Sea sector, .Antarctica 2 2 Location of stratigraphic sections in the Beardmore Glacier area 3 3 Paleocurrent data 4 4 Stratigraphic sections - in back 5,6 Photomicrographs of volcanic fragments in the Buckley Formation l2 7 Mackellar Formation near Mount Mackellar 15 8 Channeling in Mackellar Formation, Moore Mountains 15 9 Mineral composition of the Mackellar Formation 19 10-13 Trails and'burrows in the Mackellar Formation, Mount Weeks 21 14 Type section, Fairchild Formation, Tillite Glacier 24 15 Mackellar and Fairchild Formations, Lowery Glacier 24 16 Mineral composition of the Fairchild Formation 29 17 Channel in the Fairchild Formation, Clarkson Peak 30 18 Channel in the Fairchild Formation, Moore Mountains 30 19 Fairchild and Buckley Formations near Mount Wild 34 20 Rounded white quartz pebbles, Buckley Formation 34 21 Base of Buckley Formation, Moore Mountains 34 22 Upper pa.rt of Buckley Formation, Mount Miller 36 23 Volcanic sandstone, Buckley Formation, Mount Miller 36 24 Varvoid lamination, Buckley Formation, Mount Picciotto 39 25 Mineral composition of the Buckley Formation 40 viii LIST OF FIGURES - (continued) Fi5ure No. 26 Trails and burrows, Buckley Formation, Mount Picciotto 46 27 Type section of the Fremouw Formation 49 28 Buckley-Fremouw contact at Mount Kinsey 49 29 Coal in upper part of Fremouw Formation, Prebble Glacier 53 30 Percent sandstone in Fremouw Formation 53 31 Mineral composition of Fremouw Formation 58 32 Photomicrograph of vitric