The Geochemical Evolution of Alkaline Magmas from the Crary Mountains, Marie Byrd Land, Antarctica

Home , Alkali basalt, Basanite, Benmoreite, Crary Mountains, Hyaloclastite, Mount Sidley

THE GEOCHEMICAL EVOLUTION OF ALKALINE MAGMAS FROM THE CRARY MOUNTAINS, MARIE BYRD LAND, ANTARCTICA

SUVANKAR CHAKRABORTY

A Thesis

Submitted to the Graduate College of Bowling Green State University in partial fulfillment of the requirements for the degree of

MASTER OF SCIENCE

May 2007

Committee:

Kurt Panter, Advisor

John Farver

Thomas Wilch

Suvankar Chakraborty

ABSTRACT

Kurt Panter, Advisor

Late Cenozoic alkaline volcanism in the Crary Mountains, Marie Byrd Land, Antarctica is associated with the West Antarctic rift system. More than 400 km 3 (LeMasurier et al., 1990) of alkaline magmas were erupted from four major volcanic centers. Based on previous field and dating studies the volcanism occurred between ~9 and <1 Ma and the activity migrated to the south at a rate of ~0.7 cm/yr. The Crary Mountains represent one of four ranges of volcanoes in

Marie Byrd Land that show this type of age progression; younging away from the center of the province (LeMasurier and Rex, 1989; Panter et al., 2000).

The volcanic deposits at the Crary Mountains consist of lavas and interbedded agglutinated scoria deposits as well as thick hydrovolcanic sequences (hyaloclastites, pillow breccia, tuff) all of which range in composition from basanite to intermediate types to phonolite, trachyte, and rhyolite. This study focuses exclusively on lava samples that are fresh and unaltered. Basaltic rocks are consisting of olivine, clinopyroxene, plagioclase and titanomagnetite phenocrysts. Phenocrysts found in intermediate to felsic compositions include of olivine, clinopyroxene, alkali amphibole, alkali and plagioclase feldspars, nepheline, apatite, titanomagnetite, and aenigmatite. Most of the phenocrysts of different rock types are either unzoned or normally zoned and disequilibrium textures are rare. Stratigraphic sections of Mount

Steer and Rees show a complex petrographic history; however, the overall compositions of the

Crary Mountains show a change to mafic composition with progression in age.

The evolution trends and magma differentiation processes were determined based on geochemistry and geochemical relationships for these alkaline volcanic rocks. Overall, the iv alkaline lavas from the Crary Mountains show trends of increasing SiO 2, Na 2O, K 2O with decreasing MgO and CaO. On other hand highly incompatible trace elements (e.g., Th, La, Zr) show an increase in concentration with magmatic differentiation.

On the basis of geochemical studies trachytes and phonolites are divided into two groups each; nepheline-normative trachytes ( Ne-trachyte) and quartz-normative trachytes ( Qtz -trachyte); low- alkali (Na 2O + K 2O <13.46 wt% ) high silica (> 60 wt%) phonolites and high-alkali (Na 2O + K 2O

> 15.47 wt%) low silica (<56 wt%) phonolites. Using least-squares mass balance and Rayleigh fractionation models, the Ne-trachytes can best be explained by a single differentiation trend generated by fractional crystallization of a basanite magma. An explanation for the generation of quartz-normative trachytes ( Qtz -trachyte) and rhyolite can be generated by the assimilation of granitoid country rocks by mugearite magma coupled with fractional crystallization (AFC processes). Two different fractionation schemes are responsible for the production of phonolitic rocks; one that can explain the evolution of intermediate mugearite magmas to low-alkali phonolites and another from basanite to high-alkali phonolites. The modeling results indicate that the evolution of alkaline magmas erupted in the Crary Mountains is complex and these alkaline magmas were produced by a combination of magmatic differentiation processes. v

It is theory that decides what can be observed

Albert Einstein vi

ACKNOWLEDGMENTS

The author is deeply indebted to Dr. Kurt S Panter, Associate Professor, Department of

Geology, Bowling Green State University for his supervision and guidance throughout this thesis. Secondly, the author would like to thank the Geology Department at Bowling Green State

University for their challenging program from which he has learned so much. The author is grateful to Dr. Nelia Dunbar at New Mexico Institute of Mining and Technology for conducting microprobe analysis of the thin sections. Dr. Thomas I Wilch Associate Professor of the

Department of Geology, Albion College provided geochemical data, maps and valuable basic geological information of the Crary Mountains. The author expresses heartiest thanks to Dr. John

Farver, Department of Geology, Bowling Green State University for supporting him during the completion of the thesis work.

The author gives his heartiest thanks to Mr. Bill Butcher and Mr. Jagannath Paul for their moral support during the completion of the dissertation work. The author remembers, with particular pleasure, the help, co-operation and comments offered by dearest friend Jaydeep

Ghosh. Least but not the least the author wishes to recall the inspiration and blessing of his parents and his wife during the whole session of M.S. vii

TABLE OF CONTENTS

Page

INTRODUCTION ...... 1

GEOLOGICAL SETTING ...... 7

Regional Geology ...... 7

Volcanic Geology…………………………………………………………... 8

PETROLOGICAL DATA ...... 14

Petrographic types...... 14

Mineralogical Features...... 16

Mineral Compositions……………………………………………………… 16

Analytical Methods………………………………………………… 16

Olivine...... 16

Clinopyroxene...... 21

Feldspar and feldspathoids.………………………………………. 25

Fe-Ti oxides………………………………………………………. 30

Amphibole………………………………………………………… 30

Aenigmatite, apatite and quartz…………………………………… 36

WHOLE-ROCK GEOCHEMISTRY ...... 41

Major Elements...... 41

Trace Elements...... 50

DISCUSSION ………...... 55

Magmatic Evolution by Fractional Crystallization………………………………… 55

Ne-Trachyte Series………………………………………………………….. 59 viii

Phonolite Series……………………………………………………………. 65

Qtz-Trachyte Series…………………………………………………………. 69

Magmatic Evolution by Assimilation of Crust……………………………………… 73

CONCLUSIONS…………………………………………………………………………… 79

REFERENCES ...... 82

APPENDIX 1. PETROGRAPHY ...... 96

APPENDIX 2.1. OVLIVINE CHEMISTRY...... 109

APPENDIX 2.2. CLINOPYROXENE CHEMISTRY…………………………………….. 112

APPENDIX 2.3 FELDSPAR CHEMISTRY……………………………………………... 120

APPENDIX 2.4. Fe-Ti OXIDE CHEMISTRY…………………………………………… 125

APPENDIX 2.5. AMPHIBOLE CHEMISTRY…………………………………………... 127

APPENDIX 2.6. APATITE CHEMISTRY……………………………………………….. 130

APPENDIX 2.7. AENIGMATITE CHEMISTRY………………………………………… 132

APPENDIX 3. MAJOR AND TRACE ELEMENT CHEMISTRY………………………. 134 ix

LIST OF FIGURES

Figure Page

1a Regional location map of the Marie Byrd Land volcanic province of West Antarctica

(after Panter et al., 2000)...... 4

1b An outcrop map of the Crary Mountains, Marie Byrd Land...... 5

2a Cartoons simplified stratigraphic cross-sections showing major compositional rock

types at Mounts Steere and Rees. …………………………………………………. 11

2b Detailed stratigraphic section of the Lie Cliff (Mount Steere) ...... 12

2c Variation in compositions of different rock types of the Crary Mountains with

age (Ma)……………………………………………………………………………. 13

3 Total alkali (wt%) versus SiO 2 (wt%) diagram (after Le Bas et al., 1986) ...... 15

4 Photomicrograph of olivine phenocrysts within felsic groundmass...... 19

5 Clinopyroxene quadrilateral showing compositions of olivine and clinopyroxene... 20

6 Photomicrograph of clinopyroxene phenocryst in phonolite………………………. 23

7a Back scatter image (BSE) of Ti-rich clinopyroxenes in hawaiite………………….. 24

7b Photomicrograph of Ti-rich clinopyroxene in hawaiite……………………………. 24

8 Classification of cores and rims of feldspar………………………………………… 28

9a BSE of rimmed plagioclase feldspar in benmorite…………………………………. 29

9b Photomicrograph of plagioclase feldspar in Benmorite……………………………. 29

10 Variation in magnetite phenocrysts composition…………………………………... 32

11 BSE of titanomagnetites phenocrysts in phonolite………………………………… 32

12 Photomicrograph of interstitial amphibole grain in phonolite…………………….. 35

13 BSE of fayalite (Fa 98 ) inclusion within amphibole………………………………… 35 x

14 Variations in amphibole composition……………………………………………... 36

15 BSE of apatite microphenocryst and clinopyroxene……………………………… 38

16 Photomicrograph of aenigmatite microphenocryst……………………………….. 39

17 BSE of fayalite (Fy) and aenigmatite (Ae) in trachyte…………………………… 39

18a Photomicrograph of interstitial quartz in trachyte………………………………… 40

18b BSE of quartz xenocryst in phonotephrite………………………………………… 40

19 CIPW normative plots (after Cross et al., 1902)………………………………….. 47

20 Harker variation diagram…………………………………………………………. 48

21 Trace element variation diagram…………………………………………………. 51

22 Zr (ppm) vs. Nb (ppm) diagram………………………………………………….. 52

23 Ba (ppm) vs. Sr (ppm) plot of trachyte lavas…………………………………….. 52

24 Primitive mantle-normalized trace element plots of two different types of

trachytes ( Ne -trachyte and Qtz -trachyte)………………………………………… 53

25 V (ppm) vs. MgO (wt%) plot……………………………………………………. 60

26a Distribution of Sm (ppm) vs TiO 2 (wt%)…………………………………………. 60

26b TAS diagram shows the trend of proposed four different evolutionary lineages…. 61

27 Observed and calculated trace element values for Ne -trachyte series…………….. 65

28 Observed and calculated trace element values for Phonolite series………………. 68

29 Observed and calculated trace element values for Qtz -trachyte series……………. 72

30 Graphical presentation of Fractional Crystallization (FC) and Assimilation Fractional

Crystallization model 1 (AFC)……………………………………………………. 75

31 Graphical presentation of Fractional Crystallization (FC) and Assimilation Fractional

Crystallization model 2 (AFC)……………………………………………………. 76 xi

32 Graphical presentation of Fractional Crystallization (FC) and Assimilation Fractional

Crystallization model 1 (AFC)……………………………………………………. 77

xii

LIST OF TABLES

Table Page

1 Summary of petrographic features………………………………………… 17

2 Representative chemical analysis of olivine phenocrysts………………… 18

3 Representative chemical analysis of clinopyroxene phenocrysts………… 22

4 Representative chemical analysis of feldspar phenocrysts………………. 27

5 Representative chemical analysis of titanomagnetite phenocrysts………. 31

6 Representative chemical analysis of amphibole phenocrysts……………. 34

7 Representative chemical analyses of apatite and aenigmatite phenocrysts.. 37

8 Major (wt%) and trace (ppm) element analyses………………………….. 42

9 Mineral data used for Fractional crystallization models…………………. 57

10 Published mineral/melt partition coefficient (K D)……………………….. 58

11 Fractionational crystallization (FC) models for the Ne -trachyte series…... 63

12 Trace element solutions (in ppm) for FC models (Table 11)…………….. 64

13 Fractionational crystallization (FC) models for the low alkali high silica

phonolite (Model A)……………………………………………………… 66

14 Trace element solutions (in ppm) for FC models (Table 13, Model A)…. 66

15 Fractionational crystallization (FC) models for the high alkali low silica

phonolite (Model B)……………………………………………………… 67

16 Trace element solutions (in ppm) for FC models (Table 15, Model B)….. 67

17 Fractionational crystallization (FC) models for the Qtz -trachyte series….. 70

18 Trace element solutions (in ppm) for FC models (Table 17)…………….. 71

INTRODUCTION

Alkaline rocks occur in a wide variety of tectonic environments including areas of continental extension, intraplate hot spots, and back-arc settings. However, the largest volumes of alkaline rocks are found within continental rift zones (e.g. East Africa rift and West

Antarctica). Alkaline rocks related to continental rift systems show a wide range of compositions from alkali basalt and basanite to phonolite, trachyte and rhyolite. Alkaline rocks are produced by low degrees of partial melting of a fertile upper mantle source. This process forms melts that are enriched in highly incompatible elements (e.g. Rb, Ba, Th, U, etc.), including the alkali metals Na and K. Geochemical studies of mafic alkaline rocks can provide valuable information on the chemical and isotopic composition of the subcontinental mantle (e.g. Thompson et al.,

1984; Righter and Rosas-elguera, 2001; Wagner et al., 2003; Barry et al., 2003). These studies focus on primitive basalts, which are relatively unfractionated (Shoemaker and Hart, 2002) and devoid of crustal input. However, most magmas erupted through continental lithosphere are modified significantly by differentiation processes such as crystal fractionation and assimilation of crust (Gagnevin et al., 2003, Thompson et al., 2001, Panter et al., 1997; Marks and Marl,

2001). For alkaline magmas erupted in continental rift settings the differentiation processes leading to the production of highly evolved silica-undersaturated (e.g. nepheline normative phonolite), silica-saturated (olivine and hypersthene normative trachyte) and silica-oversaturated

(quartz normative trachyte and rhyolite) magmas is a matter of debate.

Many workers have studied the evolutionary history of alkaline magmas and the coexistence of silica-oversaturated and silica-undersaturated rocks. According to Kushiro

(1971), open system processes can lead silica-undersaturated magma to silica oversaturation.

Specifically under hydrous conditions a large degree of partial melting can produce a SiO 2- and 2

MgO-rich melt. Other studies (e.g., Hunter and Sparks, 1997) suggest that closed-system fractional crystallization of silica-undersaturated mineral phases can lead to silica-oversaturation.

Bardintzeff et al. (1988) proposed both silica-saturated and silica-undersaturated magmas are produced by closed system fractionation of Ca-pyroxene + Ca-amphibole + plagioclase + accessory minerals ± alkali feldspar from mantle-derived melts. Harris et al. (1999) and Kabeto et al. (2001) also proposed fractional crystallization for the production of evolved undersaturated and over-saturated alkaline rocks in western Africa and within the Kenyan rift. On the other hand, Perini et al. (2004) suggested that open system processes of fractional crystallization and assimilation of granitic country rock produced the silica-oversaturated alkaline rocks at the Vico

Volcano, central Italy. Also, Brotzu et al. (1997) suggested that prolonged differentiation processes associated with small amounts of crustal contamination produced silica-oversaturated alkaline rocks.

Alkaline magmatism in West Antarctica occurs in one of the largest zones of extended continental lithosphere in the world. The West Antarctic rift system is comparable to the East

Africa rift in size and in the composition of volcanism. The study of late Cenozoic volcanism in the West Antarctic rift system has focused primarily on the characterization of mantle sources and the role of mantle plumes in magmatism and rifting (Rocholl et al., 1995; Hart et al. 1997;

Panter et al. 2000; Rocchi et al., 2002; Finn et al., 2005). The study of the evolution of alkaline magmas in Antarctica has been detailed for only a few volcanoes. In the Ross Sea region, detailed studies by Kyle (1981; 1986), Kyle et al. (1992), and Wörner and Viereck (1990) have described the evolution to phonolitic and trachytic compositions at Mt. Erebus and Mt.

Melbourne, respectively. In Marie Byrd Land, two conflicting models have been proposed regarding the origin and evolution of alkaline magmas erupted at several volcanoes. Panter et al. 3

(1997) suggested that basanite and alkaline basalt from Mount Sidley and Mount Waesche within the Executive Committee Range (Fig. 1a.) were produced by different degrees of partial melting of the mantle and evolved along separate magma lineages by fractional crystallization and assimilation-fractional crystallization processes to produce phonolites and silica- oversaturated trachytes, respectively. LeMasurier et al. (2003) also considered rocks from the

Executive Committee Range and from Mount Murphy located in the eastern portion of the province. In contrast to the previous study, LeMasurier et al (2003) proposed that the evolved magmas were generated from isolated magma chambers where open-system high pressure fractionation of the minerals, clinopyroxene and plagioclase, in the lower crust lead to the production of silica-oversaturated trachytic magmas.

This thesis attempts to unravel the evolutionary history of magmas erupted in the Late

Cenozoic (~9 to <1 Ma) from four volcanoes that comprise the Crary Mountains, Marie Byrd

Land (Fig. 1a and 1b). No previous account or model has been proposed for the genesis of the evolved rocks from the Crary Mountains. In this study I use major elements from sixty-nine samples measured using x-ray fluorescence (XRF) by Wilch (1997) coupled with new trace element data on a subset of twenty-five samples measured by inductively coupled plasma – mass spectrometry (ICP-MS) and mineral chemistry by electron microprobe on a further subset of ten samples to evaluate magma evolution. A total of 69 lava samples were collected in 1992-3 by

Drs. Thom Wilch, Nelia Dunbar, William McIntosh and Kurt Panter. The collection defines an almost complete spectrum of alkaline compositions (Fig. 3). This is uncommon since many of the large polygenetic volcanoes in Antarctica are undissected and/or are snow and ice covered.

The samples are fresh showing little secondary alteration by low temperature processes, which can hamper interpretations of magma chemistry. A total of sixty samples have been 40 Ar/ 39 Ar 4

T 180

a map

a n

t area a

o East Antarctica West Antarctica o 90 E M 90 W o u n t a i n s

o 75 S o 140 W

Fosdick Mountains HCV Siple Berlin Ames Moulton o Range 120 W Bursey Flint

ECR Hampton Cumming Waesche Hartigan Sidley

Crary Mtns Toney Rees Steere 9Ma 8Ma Frakes 4Ma 2Ma g

Boyd r

e Takahe Murphy 0 250 75 o S km

Fig.1a. Regional location map of the Marie Byrd Land volcanic province of West Antarctica (after Panter et al., 2000), showing major volcanoes (open triangles) including the volcanoes of the Crary Mountains (solid triangles). ECR= Executive Committee Range, and HCV= Hobbs Coast Volcanics. Inset-The Transantarctic Mountains define the eastern flank of the West Antarctic Rift System, and coastal Marie Byrd Land defines the western flank of the rift. The Transantarctic Mountains are also the boundary between East and West Antarctica. 5

118 o00' W 117 o30' W 117 o W The Crary Mountains

volcanic outcrop 2000 7.52 to 9.34 (Ma) caldera rim Mount Trabucco

Rees Cliff 2000 200 m contour interval

Tasch 1600 76 o

Pk. 40' S 2709 m

3558 m Lie Cliff 5.74 to 7.38 (Ma) 32 00 Mount

2 8 Steere 2 0 4 2 0 2 4 8 0 0 0 0 0 0 76 20 0 o

0 S45'

1 Mount 600 Frakes

3654 m 2 0 3 0 6 0 0 0 32 English 00 2 8 0 Rock 0

2 76 4 0 0 2 Morrison o 0 50' S 0.03 to 4.25(Ma) 00 Rocks

Boyd Runyon 2.54 Ridge (Ma) Rock

2 0 5 10 000 2375 m

0 77 0

6 o kilometers 0 km 5 1 00' S 118 o00' W 117 o W

Fig.1b. Geological age map of the Crary Mountains. Showing age range determined by the 40 Ar/ 39 Ar dating method on four major volcanoes of this area (modified from Wilch and McIntosh, 2002).

6 dated by Wilch (1997). Dr. Kurt Panter analyzed 13 of the most mafic rocks (basanite, alkali basalt and hawaiite) for major and trace elements and isotopes of Sr, Nd and Pb in order to assess mantle sources (Panter et al., 2000).

The primary objectives of this thesis are: 1) to characterize and classify the rocks both mineralogically and geochemically , 2) to place the compositionally characterized samples from

Mounts Rees and Steere within age/stratigraphic context and, 3) to determine magma differentiation processes responsible for the evolution of strongly silica-undersaturated and silica-oversaturated compositions. .

GEOLOGICAL SETTING

Regional Geology

The West Antarctic rift system has a long and enigmatic history. Extension was initiated in the Middle Cretaceous as evidenced in the Ross Sea basin (Davey and Cooper, 1987) and in northwestern Marie Byrd Land (Luyendyk et al., 1992; Richard, 1992) and is associated with last stage of Gondwananland breakup. Between 105 Ma and 95 Ma, a switch in the magmatic character of the region indicates a change from subduction to extension (Weaver et al., 1994).

Estimates of the Cenozoic extension vary from 50 km (Lawver and Gahagan, 1994) to 100 km

(Winberry and Anandakrishnan, 2004). The major extension in the West Antarctic rift system is generally agreed to have ceased by the middle Cenozoic (Cande et al., 2000; Winberry and

Anandakrishnan, 2004). Other studies by Hinz and Block (1984), Davey and Cooper (1987) and

Hinz and Kristofferson (1987) suggest that some extension and transtension is taking place in the southern Ross Sea region of the rift.

The West Antarctic has been divided into three major volcanic provinces; Marie Byrd

Land, the Ross Embayment and the Antarctic Peninsula (LeMasurier and Thomson, 1990). The first two provinces are part of the West Antarctic Rift system; whereas the Antarctic Peninsula is a remnant of a back-arc system. Some notable large alkaline volcanic centers within each of these provinces include the currently active Mount Erebus volcano (>1,000 km 3) in the Ross

Embayment (Esser et al., 2004), Mount Takahe (780 km 3) in Marie Byrd Land (Wilch and

McIntosh, 2002), and the recently active Deception Island (Smellie, 2002) off the coast of the

Antarctic Peninsula. Different hypotheses are proposed regarding the fundamental cause of magmatism in the West Antarctic rift system - (1) active rifting caused by upwelling mantle plume(s) (Rocholl et al., 1995; Hart et al., 1997; Storey et al., 1999; Panter et al., 2000), (2) 8 passive rifting causing decompression melting and volcanism (Wörner, 1999) and (3) decompression melting of ancient metasomatised mantle sources by transtentional stresses in the

Cenozoic (Rocchi et al., 2002) or by warm, passively upwelling asthenosphere (Finn et al.,

2005).

In Marie Byrd Land, eighteen major alkaline volcanoes and numerous smaller centers are distributed across an 800 km wide area (LeMasurier and Rex, 1989) (Fig. 1a). The volcanoes within the Marie Byrd Land province vary in age from Oligocene (36 Ma) to active (Wilch,

1997). The Crary Mountains represent one of four ranges of volcanoes in Marie Byrd Land that show age progression, younging away from the center of the province (LeMasurier and Rex,

1989) (Fig. 1b). The other age progressive ranges include the Ames, Flood, and the Executive

Committee Range (Figure 1a). According to LeMasurier and Rex (1989) and Panter et al. (1994) the main reason for the age progression is fracture propagation. Panter et al. (1994) pointed out that the southward migration of volcanic activity of Mount Sidley was accompanied by distinct changes in magma composition and can be best explained by the sequential release of magmas, stored within an intricate system of conduits and chambers in the crust by a propagating fracture system.

Volcanic Geology

The Crary Mountains consist of four volcanoes that are aligned northwest to southeast:

Mounts Rees, Steere, Frakes, and Boyd Ridge (Fig. 1b). The volcanoes range from 2375 meters to 3654 meters in elevation and are mostly covered by glacial ice except for the older, more dissected centers, Mount Rees and Mount Steere, which provide excellent exposures of rock.

The volcanic history of the Crary Mountains is well known based on detailed field work and 48 high precision 40 Ar/ 39 Ar dates (Wilch, 1997; Panter et al., 2000; Wilch and McIntosh, 2002). The 9 results from Wilch (1997) show that the oldest deposits for each edifice are: 9.3 Ma for Mount

Rees, 8.6 Ma for Mount Steere, 4.3 for Mount Frakes, and 2.7 Ma for Boyd Ridge. Based on these dates, the calculated migration rate for the range is 0.7 cm/year. This migration rate is equivalent to the rate calculated for the five volcanoes of the Executive Committee Range

(Panter et al., 1994) and further supports a large scale structural control on Marie Byrd Land volcanism.

Mount Rees (2709 m), is mostly composed of interlayered mafic and felsic rocks; however, intermediate rocks are also observed in this mountain (Fig. 2a). Two different types of lithofacies are observed in this mountain i) dry brecciated and unbrecciated lavas and ii) wet palagonitized glassy hyaloclastite breccias and pillow lavas (Wilch and McIntosh, 2002). The ages of the deposits within the stratigraphic sequence, exposed at Trabucco Cliff and the base of

Tasch Peak, ranges from 9.34 ± 0.24 Ma to 8.21 ± 0.059 Ma. Mount Steere (3558 m) is also deeply dissected by cirques; exposing flow-banded rhyolite lavas and basalts (8.52 ± 0.23 Ma to

8.27 ± 0.64 Ma) overlain by trachyte and phonolite lavas (8.20 ± 0.07 Ma to 7.67 ± 0.06 Ma)

(Fig. 2). This volcano is also characterized by a second mafic phase of eruption (7.52 ± 0.06 Ma to 5.73 ± 0.04 Ma), which is dominated by alternating wet (eruption took place in water rich environment due to interactions between lavas and glacial ice) and dry lithofacies (eruption that took place subaerially) (Wilch and McIntosh, 2002). Mount Frakes (3652 m) is the least dissected of the three main volcanoes and only two lithologies are exposed; olivine-rich basalt

(4.25 ± 0.03 Ma) and anorthoclase phonolite lavas (4.17 ± 0.05 Ma). On the lower flanks of

Mount Frakes are late stage parasitic vents composed of basanite and hawaiite that are dated from 1.60 ± 0.02 Ma. to 0.035 ± 0.001 Ma. Boyd Ridge (2375 m) is almost entirely ice-covered 10 except for a small exposure of basaltic cinders (2.67 ± 0.39 Ma) and a more extensive cliff section of basaltic hyaloclastite at Runyon Rock (Panter et al., 2000).

The volcanic rocks of the Crary Mountains show a broad and relatively complete spectrum of alkaline magma compositions (Fig. 3). The vertical sections at Mount Rees and Mount Steere show a composition from mafic to felsic and felsic to mafic with stratigraphic height and age

(Fig. 2b & 2c). Tasch Peak on Mount Rees has a nearly complete compositional spectrum of lavas. The southern portion of Lie Cliff shows a dominancy of mafic lavas, whereas the central part of Lie Cliff shows a progression from mafic to felsic compositions. Quartz normative trachytes ( Qtz -trachytes) and nepheline normative trachytes ( Ne -trachyte) are mostly found in

Mount Steere and Mount Rees. However, the over all compositions of the Crary Mountains show mafic enrichment with progression of age (Fig. 2c). The older rocks of the Crary

Mountains show the maximum diversity of the composition (Fig. 2c). For the petrological study I selected rock samples from the Mount Steere and Mount Rees because they show the maximum diversity of rock compositions and they provide the best stratigraphic and 40 Ar/ 39 Ar age control.

Fig. 2a. Cartoons simplified stratigraphic cross-sections showing major compositional rock types at Mounts Steere and Rees.

12 ons with respect to age and age to (Ma) ons with respect started with “TW92” and are give after the with “TW92” “,”. started andafter give are Cliff (Mount Steere), showing compositional variati compositional showing Cliff Steere), (Mount the stratigraphicof section 2b. Lie Detailed Fig. stratigraphic height (meter). All number are sample (meter). height stratigraphic 13

Fig. 2c. Variation in compositions of different rock types of the Crary Mountains with age (Ma).

PETROLOGICAL DATA

Petrographic Types

All of the rock samples that were studied petrographically ( n = 22) are from lava flows.

The rock samples are mostly fresh, unaltered, and habitually holocrystalline to hypocrystalline.

The majority of the lavas are porphyritic and common phenocrysts include olivine, clinopyroxene, feldspars, opaque oxide (titanomagmatite) and amphibole (Table 1; Appendix 1).

Accessory minerals as microphenocrysts and groundmass phases include apatite, feldspathoids, quartz and aenigmatite. Based on major element chemistry provided by Wilch (1997) the rocks

(n = 69) are classified, using the recommendations of Le Bas et al. (1986), as tephrite, basanite, alkali basalt, hawaiite, benmoreite, mugearite, phonotephrite, tephriphonolite, trachyte, phonolite, and rhyolite (Fig. 3).

The mafic rocks (basanite, alkali basalt, hawaiite, tephrite, and phonotephrite) are finely porphyritic to micro-porphyritic and contain phenocrysts of clinopyroxene, olivine and plagioclase. Titanomagnetite generally occurs as a groundmass phase. Olivine phenocrysts in some basanites and alkali basalts reachs 5-8% by volume. Plagioclase microlites are also present in the groundmass together with clinopyroxene, olivine, titanomagnetite and apatite (Table 1).

Most of the mafic rocks are holocrystalline but a few samples have glassy groundmasses.

The intermediate rocks (mugearite, benmoreite, and tephriphonolite) are porphyritic and contain 3-15% phenocrysts. The phenocrysts in intermediate rocks consist of clinopyroxene, olivine, plagioclase, alkali feldspar, amphibole, apatite, and titanomagnetite (Table 1).

Microphenocryst and groundmass phases include olivine, clinopyroxene, alkali feldspar, titanomagnetite, apatite and nepheline. The intermediate rocks are holocrystalline to 15 hypocrystalline and alignments of plagioclase microlites in many of the samples produce a trachytic texture.

The felsic rocks (phonolite, trachyte, and rhyolite) are porphyritic and contain up to 10% phenocrysts of clinopyroxene, alkali feldspar, magnetite, amphibole, and aenigmatite.

Phonolites and a few trachyte lavas contain nepheline and olivine phenocrysts and groundmass phases, indicating that they are compositionally silica-undersaturated. Several other trachytes contain quartz, indicating a silica-oversaturation composition. The quartz occurs as an interstitial mineral, indicating last phase crystallization, perhaps from a fluid phase; however, absence of

Phonolite 14 Rees and Steere

Other Crary Mountian 12 Tephri- phonolite Trachyte 10 Phono- Tephrite O

2 Foidite Benmorite 8 Rhyolite

O+K Mugearite 2 Tephrite Basanite Na 6 Hawaiite Dacite Andesite 4 Basaltic Basalt andesite Picro- 2 basalt

0 35 40 45 50 55 60 65 70 75

SiO 2 Fig. 3. Total alkali (wt%) verses SiO 2 (wt%) diagram (after Le Bas et al., 1986), showing distribution of different rock types from the Crary Mountains. Major elements analyzed by the XRF technique (Wilch, 1997).

any fractures or veins indicates that this is not produced by any secondary alteration. All felsic lavas are hypocrystalline and some trachytes display trachytic textures. 16

Mineralogical Features

Mineral Compositions

Analytical Methods

Mineral compositions were determined using a CAMECA SX100 electron microprobe at

New Mexico Institute of Mining and Technology. The following analytical conditions were maintained during analysis: acceleration voltage 15kV, beam diameter 1-3 µm, beam current 20 nA, 10 s counting time. Detection limits are c. 0.2 wt.% for major elements and concentrations of

<0.3 wt.% are considered semi-quantitative. Analytical uncertainty is typically <1.0% for major elements and <10% for trace element analyzed. A detailed account of the analytical procedure has been given by the Bensing et al. (2005).

Olivine

Olivine phenocrysts are observed in all rock compositions except rhyolite. The olivine grains are generally fresh and unaltered, however, in a few samples iddingsite occurs near the rims (within 0.2 to 0.5 mm from the grain boundary) of some grains. The olivine phenocrysts vary from fine to medium in grain size and subhedral to euhedral in shape among all of the different rock types. Representative chemical analyses for olivine phenocrysts and groundmass olivine are presented in Table 2 and Appendix 2.1. A few olivine phenocrysts are normally zoned (i.e. cores having higher forsterite contents than rims) but the majority are homogeneous from core to rim (Table 2). In mafic rocks, olivine is often surrounded by clinopyroxene, apatite, and titanomagnetite and show resorption textures (Fig. 4).

Olivine phenocrysts in mafic rocks (tephrite) display a compositional range from Fo 74 to

Fo 70 (Fig. 4). In West Antarctica similar compositional variations for olivine phenocrysts in 17

Table 1- Summary of petrographic features of alkaline lava flows from the Crary Mountains, Antarctica. Rock types are based on TAS diagram (Fig. 3) using major elements determined by XRF (Wilch, 1997) (FeO= FeO * (Total Fe). Abbreviations: Akb.- Alkali basalt, Tephriphonolite- Tphn, Pl- plagioclase, Cpx- clinopyroxene, Phonotephrite- Phnt, Ol- olivine, Mt- magnetite, Af- alkali feldspar, Amp-amphibole, Ae- aenigmatite, Ap-apatite, Ne-Nepheline, Qtz- quartz. Texture- hc- holocrystalline, fp- finely porphyritic (<5 mm), mp- microporphyritic, hc- holocrystalline, hpc- hypocrystalline, tr- trachytic, pr- porphyritic, vp- vitrophyric.

Sample Location Rock Major Minor Phenocryst type >5% minerals OtherTotal% Texture TW92-001 N Rees Hawaiite Pl Cpx> Ol>Ap Mt 8 hc, fp TW92-006 N Rees Trachyte Af Pl>Cpx>Amp Qtz 4 hpc,mp TW92-009 N Rees Mugearite Pl Af>Cpx>Mt - 9 hpc, pr TW92-014 Rees Hawaiite Pl Cpx>Ol Mt 7 hc, fp TW92-015 Rees Trachyte Af Cpx>Amp>Ae Ol 10 hc, tr TW92-023 NE Rees Benmorite - Pl> Cpx>Ap Mt 3 hpc, mp TW92-025 Rees Phnt Af Cpx>Pl Mt 9 hc, pr TW92-031 NE Rees Mugearite Pl Cpx> Mt - 6 hpc, pr TW92-036 NE Rees Phonolite Af Cpx Mt 10 hc, pr TW92-041 NE Rees Mugearite - Pl,>Cpx Mt 4 hc,tr TW92-045 Steere Tephrite Pl Cpx>Ol>Af>Ap Mt 8 hpc, pr TW92-051 Steere Trachyte Af Cpx>Amp - 6 hpc, tr TW92-059 NE Rees Basanite Pl Ol>Cpx Mt 10 mp, hpc TW92-063 Steere Trachyte Af Cpx>Pl>Ap Mt 5 hpc, tr TW92-064 N Steere Phonolite Af Cpx>Ne Mt 12 hc, fp TW92-072 Steere Hawaiite Pl Cpx>Ol>Af Mt 6 hc, fp TW92-078 Steere Mugearite - Pl>Af>Cpx Mt 6 hpc, pr TW92-081 Steere Akb Pl Cpx>Ol Mt 5 hpc, pr TW92-082 Steere Mugearite Pl Af>Cpx Mt 10 hc, pr TW92-109 NW Rees Trachyte Af Cpx> Ol 9 hc, tr Amp>Pl>Ae TW92-179 Lie Cliff Tphn. Af Cpx>Ol Mt 15 hc, tr TW92-181 Central Phonolite Af Cpx> Amp> Mt Ap 20 vp, Steere amg TW92-183 Rees Rhyolite Qtz Af Cpx 5 hpc, tr

olite Trachyte olite Trachyte 121 121 121 174 0.79 0.9 0.03 0.42 0.43 1 2.11 1.52 3.17 9 9 5 5 1 1.22 0.05 2 1.03 1 0.04 0.01 1.83 0.09 0.01 1 0.04 .9 .9 40.3 45.7 1.4 3.01 3.01 2.99 2.99 2.99 unt Rees and Mount Steere, Crary Crary Steere, Mount and Rees unt rock types are the same as in Table 1. Tableas thein same types are rock .46 .46 33.16 33.71 34.52 29.52 49.14 50.10 44.85 42.3 63.87 16.97 15.71 17.82 20.7 0.54 d d Boyd Boyd Boyd Rees Rees Rees .19 .19 100.68 102 101.57 98.91 99.47 98.24 morite Benmorite morite Benmorite Phnt Phnt Tphn Tphn Phon Phonolite the prefix ‘TW92-’. prefix ‘TW92-’. the ne phenocrysts cores-rims analyzed in lavas from Mo from in lavas analyzed cores-rims phenocrysts ne O+FeO)*100. r= rim, c= core. The abbreviations for abbreviations c=The core. r= rim, O+FeO)*100.

38.39 38.29 34.25 34.25 36.23 36.21 38.68 38.88 33 2

Si Si 1.00 1.00 0.98 0.99 0.99 1.00 1.00 1.00 0.99 0.9 Fe Fe 0.50 0.52 1.05 1.07 0.80 0.80 0.45 0.45 1.21 1.2 Ca Ca 0.01 0.01 0.02 0.02 0.01 0.01 0.01 0.01 0.02 0.0 Mn Mn Mg 0.01 1.48 0.01 1.47 0.03 0.94 0.03 0.9 0.02 1.20 0.02 1.18 0.01 1.53 0.01 1.54 0.05 0.75 0.0 0.70 FeO FeO 23.04 23.65 43.96 44.56 34.81 34.68 20.95 20.99 CaO CaO 0.22 0.25 0.52 0.6 0.34 0.32 0.2 0.21 0.57 0.58 %Fo %Fo 74.4 73.8 46.5 45.1 59.5 59.1 77.0 77.1 37.2 54 SiO Total Total 100.03 100.44 102.03 101.87 101.57 100.84 Total 100 3.00 3.01 3.02 3.01 3.01 3.00 3.00 3.01 3.01 MnO MnO 0.29 0.26 1.24 1.33 0.8 0.8 0.29 0.26 1.86 2.02 MgO MgO 37.97 37.87 22.06 21.12 29.39 28.83 39.87 40.14 Position Position r c c r r c r c c c c c c Location Location Steere Steere Steere Steere Rees Rees Boy Rock Type Type Ben Tephrite Rock Mugearite Tephrite Mugearite Wt% oxide oxide Wt% Sample No. No. Sample 169 169 041 041 023 023 139 139 179 179

Table 2.- Representative chemical analysis of olivi analysis Representative chemical 2.- Table with No.’ssample begin All Mountains, Antarctica. = (MgO/Mg Mg# oxygens, 4 on Cations based 19 basaltic rocks have been documented in lavas from Mount Sidley (Panter et al., 1997) and on Hut

Point Peninsula, Ross Island (Kyle, 1981).

The forsterite content of olivine varies from Fo 77 to Fo 37 in intermediate rocks

(benmoreite, mugearite, and tephriphonolite) and from Fo 46 to Fo40 in phonolites. End-member fayalite compositions (~Fo 1) occur in some of the trachytes (Table 2 and Fig. 5). Similar iron- rich compositions have been reported in granitic rocks from Nambia, SW Africa (Mǜcke, 2003).

The compositions of olivine measured in the groundmass of all rock types are similar to the coexisting phenocrysts with the exception of Mn and Cr contents, which are higher in the

1mm

Fig. 4. Photomicrograph of olivine phenocrysts within felsic groundmass in phonotephrite sample, (TW92-025) showing resorption feature at phenocrysts rim. Cross Polarized light. Magnification- 40x. groundmass phase of intermediate and felsic rocks. It is also observed that the average Fo content of olivine phenocrysts in benmoreite (ca. Fo 59 ) is higher than the average Fo content of olivine phenocrysts in mugearite (ca. Fo 46 ).

Clinopyroxene crystallization temperatures were calculated using the Fe-Mg exchange model of Putirka et al. (1996). The parameters used for this model are: i. the chemical analysis of clinopyroxene (Cpx) grains are from the same rock, ii. the system must be at equilibrium 20

, Fs, and Fa are in in %. Fa molecular are and , Fs, s-rims microphenocrysts and analyzed tions of olivine and clinopyroxene phenocrysts tions clinopyroxene of olivine and core amples from Mount Rees from En, amples and Fo,Mount Steere. Wo Clinopyroxene 5. quadrilateralFig. composi showing for benmorite, hawaiites, phonolite, and trachyte s hawaiites, benmorite, for and phonolite, trachyte 21

condition, iii. olivine-liquid K D(Fe-Mg) exchange values approach 0.3, iii. iv. Cpx K D(Fe-Mg) exchange values approach 0.27. The model also depends on the Ca content of the olivine.

Olivine crystallization temperatures are sensitive to fO2 conditions and therefore as the pressure is released (i.e. decreasing fO2) the crystallization temperature is lowered and Ca content increases. Using the model of Putirka et al. (1996) the calculated temperature for clinopyroxene in basanite from the Crary Mountains are within the range of 1226-1285 ˚C. The calculations were performed using the algorithm provided in the website: http://www.csufresno.edu/geology/Faculty&Staff/Putirka/. Total pressure assumed for this model is between 11–16 kb (~36–43 km. depth). Frost et al. (1988) produce a geothermometer using two mineral phases (fayalite and Fe-Ti oxide) existing under equilibrium conditions. The calculations indicate that fayalite could be produced at 1058˚C at 1bar.

Clinopyroxene

Clinopyroxene occurs as phenocrysts and in the groundmass in all compositions except for rhyolite. The clinopyroxene phenocrysts vary from medium to coarse in grain size and subhedral to euhedral in shape among all of the different rock types. The chemical composition of representative clinopyroxenes is given in Table 3 and Appendix 2.2. and all analyses are plotted in Figure 5. Clinopyroxene grains are often found surrounded by apatite and titanomagnetite grains. Zoning is not common in the clinopyroxene grains, although a few phenocrysts in intermediate lavas and phonolite show oscillatory (Fig. 6) and normal (Sample

121; Table 3) zoning.

Chemical analyses of clinopyroxene phenocrysts and micro-phenocrysts in mafic rocks plot on the boundary between the diopside and hedenbergite fields on the pyroxene quadrilateral

(Fig. 5). Interstitial hedenbergite in sample TW92-014 (hawaiite) are pink in color and weakly 22

8 8 2 3 7 4 5 8 4 .8 .8 .7 .7 99 99 4.00 4.00 .33 .33 47.81 9.39 9.39 19.83 8.47 8.47 27.86 0.53 0.53 0.76 Rees Rees Rees Trachyte Trachyte Trachyte

.23 .23 98.99 99.03 121 121 174 174 Morrison Phonolite analyzed in lavas from the Crary the Crary from in lavas analyzed

the same as in Table 1.Table as inthesame

crophenocryst. crophenocryst. TW92-’. TW92-’. pyroxene phenocrysts core-rims and microphenocrysts and core-rims phenocrysts pyroxene Wollastonite. The abbreviations for rock types are types rock for abbreviations The Wollastonite.

Boyd Boyd Rees Rees Boyd Morrison Mugearite Mugearite Benmorite Benmorite Tphn Phonolite

Rees Hawaiite

6.38 4.71 4.56 1.7 2.61 1.73 1.76 1.34 0.76 0.68 4.73 2.95 2.56 0.7 1.09 0.77 0.53 0.48 0.8 0.61 44.65 47.42 47.11 50.51 49.84 50.96 52.35 50.57 47 3 2 2 O O 0.69 0.63 0.62 0.4 0.47 0.6 0.64 1 0.63 0.5 O 2

2 Si Si 1.72 1.81 1.82 1.94 1.92 1.93 1.96 1.97 1.97 1.9 Ti Ti 0.14 0.09 0.07 0.02 0.03 0.02 0.02 0.01 0.03 0.0 Al Al Fe 0.29 0.34 0.21 0.34 0.21 0.42 0.08 0.41 0.12 0.42 0.08 0.40 0.08 0.30 0.06 0.52 0.04 0.99 0.0 0.9 Ca Ca 0.90 0.90 0.85 0.90 0.89 0.87 0.85 0.89 0.87 0.8 Na Na 0.05 0.05 0.05 0.03 0.04 0.04 0.05 0.08 0.05 0.0 Mn Mn Mg 0.01 0.58 0.01 0.62 0.01 0.60 0.02 0.62 0.02 0.59 0.02 0.66 0.01 0.75 0.03 0.47 0.04 0.03 0.0 0.0 FeO FeO 10.54 10.68 13.13 12.83 12.95 12.73 9.5 15.85 2 Fs% Fs% 15.5 15.3 18.7 19.7 20.7 17.6 14.2 25.4 51.6 50 CaO CaO 21.93 22.07 20.6 21.86 21.6 21.38 21.28 21.19 1 SiO En% En% 33.1 34.4 33.6 32.6 31.5 35.5 40.1 25.7 1.8 2.5 TiO MnO MnO 0.17 0.21 0.43 0.45 0.46 0.58 0.39 0.78 1.05 0. MgO MgO 10.13 10.86 10.43 10.74 10.25 11.62 13.45 7.99 Total Total 99.23 99.55 99.45 99.19 99.29 100.37 99.91 99 Total Total 4.03 4.02 4.03 4.01 4.01 4.03 4.01 4.02 4.01 Na Wo% Wo% 51.5 50.3 47.7 47.7 47.8 46.9 45.7 48.9 46.6 46 Al Position Position mp mp c c r c c r c r Location Location Rees Rock Type Type Rock Hawaiite Sample No. No. Sample 014 014 041 23 23 179 121 Wt% Oxide Oxide Wt%

Mountains. All sample No.’s being with the prefix ‘ prefix the with No.’s being sample Mountains. All Table 3.- Representative chemical analysis clino of analysis Representative chemical 3.- Table m core, mp= c= rim, r= oxygens,. 6 on based Cations Ferrosillite. Wo- Fs- Enstatite, En- Abbreviation. 23 pleochroic and have one set of well developed and one set poorly developed cleavages (at 90°)

(Fig.7a &7b). The interstitial hedenbergite is the dominant phase (~30 vol%) in hawaiite sample

TW92-014. The chemical composition in Table 3 shows that the hedenbergite is highly enriched in TiO2 (2.95 wt% to 4.73 wt%) and the concentration of Ti increases towards the center of the interstitial grains. The Mg# (50) and Al 2O3 content (6.38 wt%) of the interstitial hedenbergite is higher relative to hedenbergite phenocrysts in other mafic and evolved rocks.

1mm

Fig. 6. Photomicrograph of clinopyroxene phenocryst in phonolite in Cross Polarized light. Magnification-40X.

Cpx CPx

CPx CPx 50 µm

Fig. 7a. Back scatter image (BSE) of Ti-rich clinopyroxenes in hawaiite, showing interstitial texture of clinopyroxenes surrounded by plagioclase laths.

Poorly develop cleavage

1 mm

Fig. 7b. Photomicrograph of Ti-rich clinopyroxene in hawaiite, showing poorly develop cleavage in plane polarized light. Magnification-40X.

Clinopyroxene phenocrysts and microphenocrysts show a wide diversity in composition in mugearite and benmoreite lavas (Fig. 5). The analyses of the core of the clinopyroxene phenocrysts and microphenocrysts of intermediate rocks plot at the diopside-hedenbergite boundary on the quadrilateral in Figure 5.

In phonolites and trachytes, the clinopyroxene phenocrysts and groundmass are also classified as hedenbergite. Most of the clinopyroxenes in the felsic rocks does not display any chemical variation and have similar composition throughout the grains. Clinopyroxene samples of phonolite and trachytes are enriched in Na and depleted in Ti relative to intermediate and mafic rocks (Table 3 and Appendix 3.2). In trachytic rocks the Mg#’s (~2) of clinopyroxene phenocrysts vary little but in phonolites they range from 11 to 59. Some clinopyroxene in phonolites are slightly more mafic in composition (Mg#’s 40 to 59) than what would be expected

Fe/Mg for liquidus phases in equilibrium (37-54, using K Dpyroxene-melt experimental values of 0.23-

0.30 by Sisson and Grove, 1993) with the melt. It might be possible that these ‘mafic’ clinopyroxenes were crystallized in a more mafic magma system.

Feldspar and feldspathoids

Plagioclase feldspar phenocrysts occur in all rocks as phenocrysts and groundmass phases. The phenocrysts in mafic rocks - basanites, tephrites, alkali basalts, hawaiites, and phonotephrite are mostly euhedral to subhedral in shape. Chemical analyses of plagioclase phenocrysts and groundmass are presented in Table 4, Appendix 2.3, and Figure 8. Plagioclase grains in mafic rocks are unzoned and show no reaction textures. In some intermediate rocks plagioclase phenocrysts are partly resorbed and show textural evidence for disequilibrium with their host magma. Plagioclase composition varies from labradorite in basanite to andesine in mugearite to bytownite in benmoreite to oligoclase in tephriphonolite (Fig. 8). In mugearite and 26 tephriphonolite the plagioclase phenocryst are strongly zoned and have reaction rims. However, in the groundmass phase the feldspar grains of the same rocks are unaltered and unzoned.

Rimmed and twinned plagioclase phenocrysts in benmoreite are observed (Fig. 9a & 9b) and plagioclase phenocrysts in benmoreite are more Ca-rich than in mugearite (Table 4).

Alkali feldspar phenocrysts are dominant in intermediate and felsic rocks. Generally the phenocrysts are normally zoned and groundmass phases are unzoned. Phonolitic rocks have high

Na 2O concentration (10.12 wt%) in alkali feldspar grains with respect to other rocks (Table 4 and

Appendix 3.3). The K2O concentration of alkali feldspar increases from intermediate to evolved rocks (2.01 to 6.55 wt.%) and reaches maximum concentrations in trachyte (6.55 wt.%) and phonolite (4.79 wt.%). In rhyolites, phenocrysts and groundmass alkali feldspars are common but were not analyzed. The compositional variations in alkali feldspars from albite to anorthoclase in phonolites (Fig. 8) can tentatively be explained by solid solution reaction between albite and anorthoclase in the presence of F-rich fluids (Mysen, 1991). Nepheline phenocrysts as well as groundmass nepheline are present in phonolite rocks. The grain size varies from microphenocrysts to phenocrysts and the shape varies from subhedral to euhedral.

The composition of several representative nepheline grains are given in Table 4.

00 .03 Ne mp 015 1.12 0.54 4.79 0.05 2.33 1.69 0.04 0 1.18 0.28 0.00 0. 5.02 0.03 Rees 50.14 30.75 13.12 0.50 100.54 15.06 84.44 Phonolite

- Af mp 015 1.17 0.02 7.45 6.55 0.01 2.99 0.99 0.04 0.00 0.64 0.37 0.00 0.00 5.03 0.09 Rees 67.22 18.82 60.67 35.11 101.23 Trachyte

c Af 134 0.13 0.41 8.32 4.75 0.08 0.11 2.96 1.05 0.01 0.02 0.71 0.27 0.00 0.00 5.01 1.92 67.37 20.34 70.66 26.55 101.49 Morris Phonolite yzed in from lavasthe Crary yzed

c Af 0.1 179 23.4 0.36 3.66 8.42 2.01 0.27 2.80 1.20 0.01 0.17 0.71 0.11 0.00 0.01 5.01 eviations for rock types and minerals are types minerals and rock for eviations Tphn Boyd 64.39 102.6 16.85 70.14 11.02

r Af 139 0.14 0.56 8.93 3.98 0.02 0.09 2.94 1.06 0.01 0.03 0.77 0.23 0.00 0.00 5.03 2.59 Phnt Boyd 66.35 20.28 74.77 21.93 100.34 O within minerals. minerals. within O 2

c Af 139 3.64 0.04 0.11 0.69 9.06 0.04 2.94 1.07 0.00 0.03 0.77 0.20 0.00 0.00 5.01 3.20 Phnt Boyd 67.29 20.77 76.10 20.13 101.64 of Na

- r Pl 0.2 023 0.31 4.34 0.22 2.40 1.60 0.01 0.58 0.39 0.01 0.01 0.00 5.00 0.12 Rees 52.62 29.65 11.91 99.25 59.11 38.98 Benmorite

29 c Pl 023 0.37 5.21 0. 0.19 0.04 2.48 1.52 0.01 0.51 0.46 0.02 0.01 0.00 5.00 1.68 Rees 54.76 99.71 50.56 45.79 28.43 10.41 Benmorite TW92-’. TW92-’. par phenocrysts core-rimsphenocrysts par microphenocrysts anal and

crophenocrysts. “-” below detection limit. Theabbr limit. below detection “-” crophenocrysts.

c Pl 0.5 041 27.1 0.44 8.06 6.62 0.24 0.09 2.58 1.43 0.0 0.39 0.57 0.03 0.01 0.00 5.01 2.82 Boyd 57.76 38.12 56.66 100.82 Mugearite

Pl mp 014 51.9 0.89 3.97 0.19 0.25 0.01 2.35 1.65 0.03 0.61 0.35 0.01 0.01 0.00 5.01 1.08 Rees 31.01 12.68 60.60 34.33 100.91 Hawaiite

High values of oxides are due to high concentration high to due are of values oxides High

c Pl 169 0.03 3.63 9.22 0.54 0.16 0.05 2.80 1.21 0.00 0.17 0.79 0.03 0.00 0.00 5.01 3.05 63.25 23.29 17.22 79.13 Steere 100.16 Tephrite Note- Note-

r Pl 169 0.06 3.79 8.19 0.63 0.15 0.03 99.4 2.81 1.22 0.00 0.18 0.71 0.04 0.00 0.00 4.96 3.85 23.35 19.44 76.00 63.18 Steere Tephrite

O O 2

2 2 clase K Si Sr Al Fe Ca Ba Na SrO FeO K CaO BaO SiO lbite

Total Total Na Al tho

orthosite Mineral Position A Location Rock Rock Type Sample No. Sample Wt% Oxide Wt% Or the same as in Table 1. asTable 1. in the same Table 4.- Representative chemical analysis of feldsanalysis Representative 4.- chemical Table with prefixthe being Mountains.‘ sample No.’s All An mi mp= core, c= rim, r= 8 oxygens. based on Cations 28

Fig. 8. Classification of cores and rims of feldspar phenocrysts and microphenocrysts in lavas from Mount Steere and Mount Rees. An, Ab, and Or are molecular wt%.

Plagioclase

Rim

500 µm

Fig. 9a. BSE of rimmed plagioclase feldspar in Benmorite.

1mm

Fig. 9b. Photomicrograph of plagioclase feldspar in Benmorite showing twining, taken in cross polarized light. Magnification 40X.

Fe-Ti oxides

With the exception of rhyolite, all samples studied contain magnetite. Table 5 and

Appendix 2.4. represents the chemical compositions of selected Fe-Ti oxide phenocrysts and groundmass in the different rock types. The compositions of titanomagnetite (Ti > 0.13 afu) cluster near the tie-line between magnetite (Fe 3O4) and ulvospinel (Fe 2TiO 4) in Figure 10.

Backscatter electron image (Fig 11) show trellis exsolution textures (Buddington and Lindsley,

1964) in many of the magnetite phenocrysts. This type of texture is produced by exsolution of ilmenite in magnetite. Overall, the ferric iron contents of magnetite phenocyrsts increase progressively from hawaiite and mugearite (average 12.7 wt.% and 29.5 wt.%, respectively) and then are lower in phonolites (average 26.1 wt.%). The groundmass titanomagnetites are richer in ferric iron than the corresponding phenocrysts. Concentrations of MnO and TiO 2 in titanomagnetite increase and MgO and Al 2O3 decrease from basanite to phonolite and trachyte.

Amphibole

Amphibole occurs in small amounts (1-3 vol%) as phenocrysts and microphenocrysts and interstitial grains in intermediate and felsic rocks. Absence of zoning in these amphibole grains

(Fig. 12) indicates equilibrium conditions prior to eruption. Amphiboles are often closely associated with clinopyroxenes and apatite phenocrysts. Several amphibole phenocrysts in trachyte contain inclusions of fayalite (Fig. 13).

31 4 68 orrison e the e inTableas same 1. ts analyzed in lavas from the Crary from in lavas ts analyzed e Tphn Phonolite Phonolite icrophenocryst. The icrophenocryst. The types abbreviations for rock ar TW92-’. TW92-’. omagnetite phenocrysts core-rims microphenocrys and core-rims phenocrysts omagnetite 62.06 45.34 70.87 69.62 66.71 73.79 83.2 74.08 8.53 0.2 2.02 2.73 2.24 2.33 0.49 1.01 18.24 46.66 23.29 17.96 24.53 19.67 5.87 15.14 3 0.14 0.06 0.42 0.08 0.11 0.61 0.35 -0.64

2 2

Si Si 0.44 0.02 0.13 0.03 0.03 0.20 0.14 0.00 Ti 4.23 9.91 5.50 4.51 5.90 4.74 1.74 4.11 Al Al Fe 3.12 16.10 0.07 10.71 0.75 18.61 1.08 19.45 0.84 17.85 19.77 0.88 27.42 0.23 22.37 0.43 Ca 0.00 0.02 0.11 0.03 0.00 0.01 0.07 0.03 Mn Mg 0.13 2.23 0.29 1.04 0.30 0.59 0.22 1.59 0.26 0.75 0.30 0.72 0.36 0.06 0.39 0.34 FeO CaO 0.01 0.06 0.32 0.09 0.01 0.03 0.16 0.09 SiO TiO MnO MnO 0.48 1.23 1.11 0.77 0.96 1.11 1.08 1.28 MgO MgO 4.83 2.46 1.27 3.19 1.57 1.51 0.09 0.64 Total 26.06 22.04 25.99 26.92 25.64 26.62 30.01 27. Total 94.29 96.02 99.32 94.5 96.13 99.08 91.23 92.2 Al2O Sample 169 014 041 139 023 179 134 121 Position Mp mp mp mp c c c c Location Steere Rees Boyd Boyd Rees Boyd Morrison M Rock Rock type Tephrite Hawaiite Mugearite Phnt Benmorit Ilmenite% 5.0 4.0 3.4 4.6 3.8 3.4 1.8 1.2 Wt% Oxide Magnetite% 84.3 81.7 85.1 87.2 86.4 87.9 94.1 92.3 Ulvospinel% 10.7 14.3 11.5 8.2 9.8 8.5 4.1 6.5 Mountains. All sample No.’s being with the prefix prefix ‘ the with No.’s being sample Mountains. All c=Cationsrim,core, r= mp=on 32 oxygens. based m Table 5.- Representative chemical analysis oftitan analysis Representative chemical 5.- Table 32

Hawaiite

e it Phonolite n e Phonotephrite lm I Tephrite l e n i Benmorite p s o v l U

Magnetite Fe O 2 3

Fig. 10. Variation in magnetite phenocrysts composition for samples from Mount Steere and Mount Rees. FeO, TiO 2, and Fe 2O3 are wt%.

10 µm .

Fig. 11. BSE of titanomagnetites phenocrysts in phonolites. The type of exsolution texture is known as terellis-type (Buddington and Lindsley, 1964). 33

Representative amphibole compositions are listed in Table 6 and Appendix 2.5. A wide range of amphibole compositions are displayed in Fig. 14. Amphiboles in tephrites and benmoreite are more FeO- and MgO-rich relative to those found in phonolites and trachytes and amphiboles in phonolite are more calcic and less alkali-rich relative to those in trachytes. On the basis of classification scheme proposed by Leake et al. (1997) amphiboles are classified from pargasite to ferropargasite (core to rim) and kaersutite to hastingsite (core to rim) in phonolites.

In trachytes, the amphibole varies from ferrorichterite to arfvedsonite and in benmoreite the composition varies from kaersutite to ferrokaersutite (core to rim) (Table 6 and Appendix 3.5).

Ferrorichterite in trachyte is characterized by a small range in Mg#’s (0 to 0.75) (Appendix 3.5), high alkali, and FeO contents, moderate TiO 2, and low Al 2O3 contents with respective to kaersutite and ferrokaersutite of benmoreite. Arfvedsonite in trachytes is rich in MgO, poor in

Al 2O3 and CaO, and contains unusually high concentrations of MnO with respect to other amphiboles. Such high MnO contents could result from low oxygen fugacities ( fO2). High fO2 conditions can prevent Fe-Ti oxides from crystallizing in trachytes and rhyolites (Ngounouno et al., 2003) and may explain why some trachyte samples of Mount Rees and Steere are devoid of

Fe-Ti oxides .

It is interesting to note that the compositions of kaersutite phenocrysts in phonolites are very similar to kaersutite phenocrysts in tephrite, which may indicate that kaersutite in phonolites are cognate xenocrysts. In support of this interpretation, the amphibole grains in phonolite have resorbed anhedral shapes and are large relative to other phenocrysts within the sample.

Table 6.- Representative chemical analysis of amphibole phenocrysts and microphenocrysts core-rims analyzed in lavas from the Crary Mountains. All sample No.’s being with the prefix ‘TW92-’.

Rock Type Tephrite Benmorite Benmorite Phonolite Phonolite Trachyte Trachyte Trachyte Sample 169 23 23 134 134 15 15 15 Location Steere Rees Rees Morrison Morrison Rees Rees Rees Position c c r c r r c r

Wt%

SiO 2 39.24 39.83 40.14 39.56 39.48 49.85 49.74 49.5

TiO 2 5.25 5.38 5.16 4.57 3.87 0.47 0.18 0.56

Al 2O3 13.85 11.52 11.15 13.25 12.62 0.13 0.14 0.16 MnO 0.17 0.33 0.33 0.23 0.29 1.05 1.01 1.1 FeO 14.12 16.53 16.81 15.12 18.1 34.09 34.48 34.02 MgO 10.67 9.36 9.16 10.36 8.61 0.05 0.01 0.07 CaO 11.28 11.43 11.33 11.17 10.95 3.14 2.85 2.98

Na 2O 2.74 2.83 2.77 2.7 2.9 7.04 7.13 6.74

K2O 0.92 0.92 0.93 0.76 0.78 1.42 1.48 1.39

H2O 1.81 1.98 1.97 1.98 1.95 1.83 1.82 1.82 Cl - - - 0.03 0.03 0.03 0.05 0.03 Total 100.05 100.11 99.76 99.75 99.59 99.13 98.93 98.39

Si 5.86 6.04 6.11 5.96 6.04 8.12 8.14 8.12 Ti 0.59 0.61 0.59 0.52 0.45 0.06 0.02 0.07 Al 2.44 2.06 2.00 2.35 2.28 0.03 0.03 0.03 Mn 0.02 0.04 0.04 0.03 0.04 0.15 0.14 0.15 Fe 1.76 2.10 2.14 1.90 2.32 4.64 4.72 4.67 Mg 2.37 2.11 2.08 2.33 1.96 0.01 0.00 0.02 Ca 1.80 1.86 1.85 1.80 1.80 0.55 0.50 0.52 Na 0.80 0.83 0.82 0.79 0.86 2.23 2.26 2.15 K 0.18 0.18 0.18 0.15 0.15 0.30 0.31 0.29 Total 17.74 17.83 17.80 17.82 17.89 18.07 18.12 18.02

Mg# 43.0 36.2 35.3 40.7 32.2 0.2 - 0.2 Name Kaersutite Kaersutite Ferrokaer- Kaersutite Hastings- Ferrorich- Arfvedso- Ferrorich- sutite ite terite nite terite

Cation based on 23 oxygens. Amphiboles are named using the program developed by Esawi (2004), which is based on the classification scheme of Leake et al., 1997. r= rim, c= core. “-” below detection limit.

1mm

Fig. 12. Photomicrograph of amphibole phenocryst in phonolite taken in plane polarized light. Magnification 40X.

Amphibole

10 µm Fa

Fig. 13. BSE of Fayalite (Fa 98 ) inclusion within amphibole grain in trachyte.

2 Tephrite Phonolite Trachyte Benmorite Alkali

Na-Ca Na

Fe-Mg-Mn

Calcic Rim Core 0 0 2 Ca+Na Fig. 14. Variation in amphibole composition on the basis of Ca+Na (afu) vs. Na (afu) for lavas from Mount Steere and Mount Rees. Classification grid from Hawthorne (1981).

Aenigmatite, apatite and quartz

Apatite is common as euhedral inclusions in clinopyroxenes and olivines, as microphenocrysts, and as a groundmass phases (Fig. 15). Apatite in benmoreite, mugearite, tephriphonolite and phonolite show negligible chemical variation between inclusions and microphenocrysts (Table 7 and Appendix 2.6).

2+ Phenocrysts and microphenocrysts of aenigmatite (Na2Fe 5TiSi 6O20 ) occur in trachytes

(Table 7 and Appendix 2.7) where they are often found adjacent to clinopyroxene, amphibole,

(Fig. 16) and fayalite (Fig. 17). Possible hydrothermal reaction that produces aenigmatite is given by Schoenenberger and Markl (2005): 37 in lavas in lavas from the Crary

r r c Ae Ae Ae achyte achyte Trachyte

Ae Ae mp mp

s below detection limit.detectionbelows TW92-’. te te phenocrysts and aenigmatite and microphenocrysts

Ap Ap mp mp mp Morrison Rees Rees Rees Rees Rees - - 0.31 0.27 0.36 0.28 - - 38.52 0.46 41.76 0.4 0.01 7.36 0.01 6.82 0.04 0 - - 48.21 48.06 40.97 41.26 3 2 5 2 O - - 0 1.34 7.05 7.19 O 2

O 2 F 5.39 4.01 - - - - 2 Cl 0.04 0.24 - - - - SrO SrO 0.13 0.12 - - - - FeO 1.54 1.3 29.1 28.89 41.59 41.92 CaO 52.87 53.46 18.81 18.77 0.34 0.25 SiO P TiO MnO MnO MgO 0.08 0.05 0.99 1.05 0.86 0.19 0.87 0.19 0.02 - Total 99.29 101.26 98.07 98.99 98.66 98.61 Na Al Position Location Rocky Rocky type Phonolite Benmorite Trachyte Trachyte Tr Sample No. 121 23 15 15 15 15 Wt%Oxide

Table 7.- Table Representative apatichemical ofanalyses Mountains.All withbeing sample No.’s the prefix‘ core, rim,r=c= =microphenocrysts.mp indicate “-” 38

(fluid) 2+ (fluid) Fe 3TiO 4 + 2 NaAlSi 3O8 + 3 FeO → Na 2Fe 6TiSi 6O20 + Al 2O3

(titanomagnetite) (albite) (aenigmatite)

However, in the trachytic rocks of the Crary Mountains there are no evidence of hydrothermal effects (e.g., oxidation of Fe-Ti oxide, secondary carbonates, and kaolinization).

The mineral assemblage and textures associated with aenigmatite grains indicates that this mineral has been produced by magmatic processes. Fe-Ti oxides does not immediately surround the aenigmatite grains which supports the idea that the there has been a subsolidus reaction between titanomagnetite and Na-feldspar to produce the aenigmatite (Marsh, 1975).

Quartz is present only in trachyte and rhyolite lavas. Quartz occurs as an interstitial mineral suggesting that it formed in the latest stage of crystallization (Fig. 18.a). Quartz is also found as a xenocryst in phonotephrite (Fig. 18.b).

apatite

Cpx

10 µm

Fig. 15. BSE of apatite microphenocrysts associated with clinopyroxene grains in benmorite.

1mm

Fig. 16. Photomicrograph of aenigmatite microphenocryst surrounded by Clinopyroxene grains in phonolite sample taken in plane polarized light. Magnification- 50X.

Af Ae

Af 100 µm Fy

Fig. 17. BSE of fayalite (Fy) and aenigmatite (Ae) phenocrysts in trachyte. Aenigmatite occurs as a rim on the fayalite grain. Abbreviations: Af-Alkali Feldspar, Ae-Aenigmatite, Fy-Fyalite. 40

Qtz

1mm

Fig. 18.a. Photomicrograph of interstitial quartz in trachyte under cross polarized light. Magnification-20X.

quartz hole

500 µm

Fig. 18.b. BSE of quartz xenocryst in phono tephrite. 41

WHOLE-ROCK GEOCHEMISTRY

Representative whole-rock lava samples from the Crary Mountains were analyzed by

XRF and ICP-MS (Table 8 and Appendix 3). A total of sixty nine samples were analyzed by

XRF (Wilch, 1997) and a subset of twenty five lavas from Mount Steere and Rees were analyzed for trace element concentrations using an ExCell quadrupole ICP-MS at Boston University under the direction of Dr. Terry Plank. The instrument uses an off-axis lens system which has decreased instrument background interference to < 0.5 cps. The routine precision in solution is

1-2% RSD for most trace elements. Representative analyses of major and trace element data are given in Table 8. A few lava samples (~10 samples) have LOI >1.0 wt.%, athough the majority lava samples have lower LOI contents and appear fresh and unaltered in thin section. Major element data used in plots are recalculated on a 100% volatile-free basis with total Fe as FeO t.

Major Elements

Lavas from the Crary Mountains are classified based on the criteria of Le Bas et al.

(1986) as basanite, tephrite, alkali basalt, hawaiite, mugearite, benmoreite, phonotephrite, tephriphonolite, trachyte, phonolite, and rhyolite (Fig. 3). The relatively complete compositional spectrum of the Crary Mountain rocks shown in Figure 3 clearly indicates that the “Daly Gap”

(Daly, 1910) is not present in this rock suite. However, for the rocks sampled from Mounts Rees and Steere, intermediate compositions are less common.

Except for rhyolite and some trachytes all samples are silica-undersaturated with between

2 and 20 wt.% normative nepheline (Table 8, Appendix 3.8, and Fig. 19). Variations within the entire data set show that with decreasing MgO content the Al 2O3, Na 2O and K2O increase and

FeO and CaO decrease (Fig. 20). In addition, TiO 2 and P 2O5 initially increase and then decrease

Table 8.- Major (wt%) and trace (ppm) element analyses of lavas from the Mount Steere and Mount Rees, volcanoes, Crary Mountains, Antarctica. 42

Table 8.- Major (wt%) and trace (ppm) element analyses of lavas from the Mount Steere and Mount Rees, volcanoes, Crary Mountains, Antarctica.

SAMPLE 001 006 023 031 036 041 051 LOCATION N. Rees N. Rees NE. Rees NE. Rees NE. Rees NE. Rees N. Mt. St AGE 9.13±0.53 8.97±0.068 8.91±0.12 - 7.5±0.059 8.5±0.16 8.325±0.061 NAME(TAS) Hawaiite Trachyte Benmorite Mugearite Phonolite Mugearite Trachyte

SiO 2 44.36 65.81 54.54 51.19 60.01 52.67 59.83

TiO 2 3.44 0.35 1.14 1.71 0.20 1.78 0.67

Al 2O3 15.66 13.86 18.53 18.91 18.69 16.85 16.64 FeO t 15.33 6.60 8.40 9.33 5.30 11.42 6.95 MnO 0.23 0.17 0.22 0.18 0.15 0.27 0.19 MgO 4.54 0.00 1.24 1.75 0.07 1.96 0.34 CaO 9.15 0.79 4.10 6.32 1.25 5.27 2.02

Na 2O 4.09 7.06 6.68 6.06 8.72 6.13 6.52

K2O 0.99 4.79 2.69 2.49 5.04 2.20 4.38

P2O5 0.46 - 0.31 0.59 0.03 0.59 0.11 LOI 1.33 0.15 1.70 1.11 0.44 1.00 1.87 TOTAL 99.60 99.57 99.56 99.64 99.90 100.14 99.53 Q - 8 - - - - - Or 6 28 16 15 29 13 26 Ab 28 47 51 39 43 48 59 Ne 6 - 6 10 16 5 - Hy - 5 - - - - 1 Ol 8 - 5 4 2 6 1 Di 18 3 5 8 5 8 5 Ac - 5 - - 5 - - Mg# 22.8 - 12.9 15.8 1.3 14.6 4.7

Sc 18.10 2.23 6.39 10.07 1.41 11.44 3.98 V 253 - 12 31 9 - 20 Cr 2 5 - - 3 - - Co 49.49 11.54 13.10 16.76 10.52 16.15 6.49 Ni 7 3 3 4 4 4 3 Cu 21.85 3.71 11.26 17.93 13.78 15.26 5.22 Zn 103.47 247.22 85.68 70.43 109.43 117.95 129.84 Ga 24.55 41.07 22.15 20.35 25.63 24.83 30.48 Rb 21.44 224.02 52.63 58.18 162.40 34.90 108.03 Sr 663.06 1.40 463.22 713.72 50.33 521.32 138.06 Y 30.14 122.21 45.91 36.41 41.59 50.75 55.14 Zr 218.18 1092.96 543.07 392.12 863.27 393.91 491.60 Nb 56.10 227.05 163.26 109.23 211.04 111.66 122.59 Cs 0.28 5.98 0.75 0.57 2.25 0.62 0.45 Ba 298.90 15.56 765.82 702.28 662.84 779.90 1064.86 La 36.62 160.04 91.71 67.18 123.01 71.87 74.52 Ce 74.04 307.63 165.52 125.06 201.57 138.84 140.63 Pr 9.01 35.25 17.89 14.06 19.27 16.21 15.69 Nd 32.58 117.32 57.79 47.09 52.80 55.85 50.50 Sm 6.56 23.09 9.93 8.36 7.77 10.54 9.42 Eu 2.14 2.43 2.72 2.67 1.30 3.46 2.72 Gd 6.08 21.04 8.51 7.22 6.32 9.51 8.59 Tb 0.91 3.36 1.32 1.09 1.03 1.45 1.38 Dy 5.13 19.72 7.45 5.95 5.75 8.19 8.14 Ho 1.20 4.79 1.80 1.41 1.43 1.97 2.02 Er 2.56 10.70 4.10 3.13 3.45 4.28 4.58

Continued- 43

Continued-

Tm 0.37 1.64 0.64 0.48 0.58 0.65 0.73 Yb 2.29 10.18 4.12 3.00 3.91 4.04 4.66 Lu 0.34 1.49 0.63 0.45 0.62 0.61 0.70 Hf 4.67 23.32 10.35 7.10 14.27 7.72 9.03 Ta 3.25 12.72 8.95 5.86 11.39 5.97 6.89 Pb 2.69 34.90 8.97 5.86 14.42 6.85 13.78 Th 3.94 29.43 14.26 8.86 23.24 8.73 13.46 U 1.05 8.25 3.61 1.45 5.35 2.32 1.51

SAMPLE 053 059 064 082 085 091 93 LOCATION N. Mt. St NE. Rees N. Mt. St C. Lie. St C. Lie. St N. Mt. St. N. Mt. St AGE 8.23±0.083 9.34±0.24 8.0±0.076 8.2±0.21 8.3±0.33 8.45±0.089 8.2±0.080 NAME(TAS) Trachyte Basanite Phonolite Mugearite Hawaiite Trachyte Rhyolite SiO 2 58.64 43.00 58.69 49.21 46.93 65.28 68.15 TiO 2 0.69 2.96 0.15 2.48 2.48 0.34 0.23 Al 2O3 16.75 16.31 19.01 15.59 18.33 14.91 14.20 FeO t 7.12 15.17 5.83 13.97 12.73 6.10 3.85 MnO 0.20 0.19 0.17 0.27 0.21 0.19 0.14 MgO 0.49 5.92 - 2.78 3.03 0.10 - CaO 2.29 11.39 1.00 7.10 9.91 1.49 1.65 Na 2O 6.66 2.79 9.39 4.82 4.11 6.12 5.37 K2O 4.34 0.64 4.99 1.93 1.15 5.26 5.19 P2O5 0.12 0.29 0.01 0.87 0.48 0.03 - LOI 2.41 0.93 1.02 0.99 0.97 0.01 0.89 TOTAL 99.71 99.58 100.26 100.01 100.32 99.79 99.67 Q - - - - - 5 14 Or 26 4 29 12 7 31 31 Ab 56 18 39 41 30 50 47 Ne 3 5 20 2 5 - - Hy - - - - - 3 - Ol 2 11 3 8 6 - - Di 6 20 4 12 15 6 4 Ac - - 4 - - 4 1 Mg# 6.4 28.1 - 16.6 19.2 1.6 -

Sc 4.22 25.88 1.13 11.49 15.93 1.43 1.63 V 19 359 11 - 129 10 7 Cr - 24 2 - 6 5 5 Co 7.71 56.90 19.76 25.47 37.70 13.13 11.37 Ni 5 49 6 7 10 5 3 Cu 5.79 73.17 2.87 13.96 21.34 3.63 2.85 Zn 133.90 80.23 199.79 127.50 89.03 159.07 172.33 Ga 29.85 22.34 40.11 24.57 23.66 33.42 32.62 Rb 128.07 12.63 136.49 40.47 25.67 131.19 202.26 Sr 140.66 589.33 4.81 533.64 673.39 25.88 40.36 Y 52.03 20.58 106.87 47.66 27.88 66.32 80.82 Zr 441.76 129.95 1054.97 283.63 179.45 461.74 652.46 Nb 132.85 32.06 271.96 93.04 52.80 100.02 140.16 Cs 0.58 0.16 1.84 0.55 0.30 1.85 2.41 Ba 1214.25 184.82 94.50 560.01 331.35 374.12 671.04 La 76.45 21.73 138.16 64.02 35.34 84.65 103.43 Ce 142.77 44.75 251.59 125.84 69.16 166.79 196.19 Pr 16.08 5.52 27.14 14.94 8.20 19.67 22.29 Nd 51.65 20.60 86.93 52.36 28.98 64.44 72.63 Sm 9.55 4.33 16.38 10.00 5.66 12.33 13.80 Eu 2.94 1.47 2.24 3.04 1.86 2.76 2.49 Gd 8.46 4.08 15.45 9.21 5.23 11.00 12.56 Tb 1.35 0.62 2.60 1.38 0.78 1.72 2.01 Dy 7.89 3.50 15.88 7.77 4.48 10.00 12.04 Ho 1.93 0.82 4.07 1.85 1.06 2.43 2.97 Er 4.37 1.71 9.41 4.02 2.31 5.46 6.78 Tm 0.70 0.25 1.50 0.59 0.34 0.85 1.06 Yb 4.49 1.51 9.31 3.72 2.15 5.51 6.65 Lu 0.67 0.22 1.35 0.55 0.32 0.86 0.98 Hf 8.55 2.95 20.34 5.92 3.54 9.59 13.77 Ta 6.94 1.85 14.68 4.85 2.94 5.94 7.72 Pb 13.97 1.62 16.23 5.61 3.11 18.34 26.86 Th 13.46 2.26 21.85 7.55 4.13 13.38 22.85 U 5.87 0.59 5.91 1.31 0.89 1.66 5.55

SAMPLE 109 160 162 174 179 181 183 LOCATION NW. Rees Lie ridge S. Lie. St N. Rees Lie cliff C. Mt. St C. Mt. St AGE 8.69±0.075 - 6.6±0.048 8.9±0.057 - 7.9±0.20 8.5±0.058 NAME(TAS) Trachyte Benmorite Akb Trachyte Tphn Phonolite Rhyolite SiO 2 58.88 56.69 45.31 62.73 55.23 58.52 72.65 TiO 2 0.47 0.85 1.99 0.49 0.84 0.19 0.20 Al 2O3 17.26 17.03 14.72 14.69 18.59 17.84 12.06 FeO t 8.21 9.38 13.33 8.23 8.37 6.52 3.91 MnO 0.24 0.27 0.20 0.24 0.23 0.22 0.08 MgO 0.35 0.73 10.86 0.01 1.02 0.00 0.00 CaO 2.63 3.04 8.94 1.52 3.23 0.97 0.18 Na 2O 6.93 7.11 3.68 6.82 7.71 8.37 5.51 K2O 4.27 3.73 0.98 4.96 3.55 4.72 4.62 P2O5 0.10 0.25 0.38 0.03 0.30 0.01 0.00 LOI 0.18 0.76 0.49 0.04 0.68 2.39 0.37 TOTAL 99.51 99.85 99.90 99.68 99.76 99.76 99.59 Q - - - 1 - - 24 Or 25 22 6 29 21 28 28 Ab 52 50 19 51 44 45 39 Ne 6 9 8 - 15 14 - Hy - - - 5 - - 3 Ol 3 4 23 - 4 4 - Di 7 8 17 6 7 41 1 Ac - - - 6 - 5 5 Mg# 4.1 7.2 44.9 0.1 10.9 - -

Sc 5.99 6.49 22.86 1.74 4.82 0.88 2.22 V 1 3 178 3 6 5 5 Cr 4 2 425 1 4 - 1 Co 9.02 9.64 58.71 11.98 12.90 4.84 8.43 Ni 4 7 281 4 3 3 5 Cu 6.33 13.06 68.52 3.96 17.30 2.76 3.28 Zn 152.89 146.51 79.34 169.63 111.68 181.43 259.92 Ga 31.28 28.03 18.23 33.22 25.65 36.05 37.09 Rb 83.28 70.14 23.05 107.23 85.65 116.76 263.25 Sr 223.88 237.35 523.87 2.70 350.08 13.81 0.07 Y 66.08 61.64 25.68 64.94 52.47 87.12 121.62 Zr 612.81 545.53 167.73 516.84 520.77 784.11 884.14 Nb 172.50 152.56 53.59 115.92 162.74 237.15 227.86 Cs 0.71 1.25 0.24 0.88 1.41 4.32 5.28 Ba 1972.92 1192.84 329.91 97.98 1018.71 346.36 0.49 La 91.62 91.12 32.92 83.61 92.80 122.09 281.90 Ce 175.51 167.94 63.78 167.43 169.50 225.33 298.00 Pr 20.10 18.76 7.33 19.66 18.18 24.63 59.26 Nd 70.18 62.01 25.84 64.15 57.82 79.27 198.23 Sm 12.99 11.29 5.03 12.45 10.00 14.75 38.27 Eu 4.22 3.31 1.65 2.16 2.94 2.80 2.87 Gd 11.47 10.16 4.70 11.19 8.76 13.66 31.46 Tb 1.84 1.62 0.72 1.76 1.40 2.22 4.41 Dy 10.82 9.55 4.13 10.20 8.08 13.15 21.90 Ho 2.64 2.33 0.99 2.44 2.00 3.27 4.94 Er 6.03 5.32 2.13 5.49 4.64 7.70 10.77 Tm 0.96 0.83 0.32 0.85 0.73 1.23 1.60 Yb 6.21 5.40 2.00 5.48 4.75 7.89 10.03 Lu 0.97 0.83 0.30 0.85 0.71 1.17 1.46 Hf 12.56 10.51 3.52 10.41 9.87 16.87 21.16 Ta 8.48 8.06 2.83 6.12 8.70 12.12 13.21 Pb 11.14 10.67 2.12 16.49 9.40 13.59 35.97 Th 13.16 13.34 3.42 13.02 14.57 17.01 33.57 U 2.97 3.56 3.51 3.40 2.50 10.82 0.96

SAMPLE 186 190 192 193 139 LOCATION N. Lie. St N. Lie. St N. Lie. St N. Lie. St Boyd AGE 8.4±0.11 8.2±0.64 8.2±0.065 - - NAME(TAS) Hawaiite Hawaiite Phonolite Mugearite Phnt

SiO 2 46.18 45.69 59.01 51.80 48.62 TiO 2 2.84 2.85 0.40 1.47 2.10 Al 2O3 15.86 15.62 17.26 17.21 17.76 FeOt 15.47 15.24 7.50 11.86 11.68 MnO 0.25 0.25 0.24 0.25 0.21 MgO 4.50 4.00 0.23 1.92 4.63 CaO 9.01 8.73 1.49 5.62 6.88 Na 2O 4.26 4.17 7.79 6.43 6.12 K2O 1.03 1.01 4.95 2.06 2.00 P2O5 0.41 0.52 0.04 0.63 0.54 LOI 0.58 1.69 0.89 1.16 0.43 TOTAL 100.38 99.76 99.79 100.41 100.12 Q - - - - - Or 6 6 29 12 11.52 Ab 29 32 45 44 30.04 Ne 6 4 12 9 13.49 Hy - - - - - Ol 10 9 4 7 11.45 Di 17 16 6 10 9.30 Ac - - 4 - - Mg# 22.5 20.8 3.0 13.9 28.4

Sc 19.71 19.02 2.47 8.35 - V 224 207 - - 116 Cr 4 6 - - 12 Co 54.38 41.05 5.04 14.84 - Ni 13 9 3 7 24 Cu 29.44 33.37 5.45 10.59 40 Zn 103.19 103.15 151.00 110.64 81 Ga 23.45 23.69 32.98 23.24 19.00 Rb 22.34 21.31 131.86 45.32 62.00 Sr 586.03 557.37 12.13 614.64 751.00 Y 29.48 33.15 77.76 43.49 34.00 Zr 185.33 218.48 703.02 318.14 308.00 Nb 54.39 63.40 219.78 95.69 88.00 Cs 0.28 0.32 2.15 0.56 - Ba 306.65 362.88 445.71 556.36 544.0 La 35.03 41.07 105.69 64.35 61.00 Ce 69.35 81.22 193.71 123.90 122.00 Pr 8.24 9.53 20.79 14.10 - Nd 29.04 33.01 65.60 47.56 45.00 Sm 5.82 6.45 12.30 8.87 - Eu 1.95 2.10 2.08 2.87 - Gd 5.43 5.97 11.32 7.93 - Tb 0.82 0.91 1.88 1.23 - Dy 4.71 5.18 11.34 6.87 - Ho 1.13 1.24 2.86 1.67 - Er 2.43 2.70 6.70 3.66 - Tm 0.37 0.40 1.10 0.57 - Yb 2.24 2.53 7.05 3.53 - Lu 0.34 0.38 1.07 0.53 - Hf 3.85 4.38 15.59 6.36 - Ta 3.29 3.40 11.26 4.98 - Pb 2.71 3.36 14.82 5.00 12.00 Th 3.81 4.66 19.48 7.58 1.27 U 1.09 0.74 0.97 0.79 - Samples were analysed by XRF for major elements and for S, V, Cr and Ni (Wilch, 1997). Trace elements were analyzed by ICP-MS. Wt% normative analyses are Q- quartz, Or -orthoclase, Ab -albite, Ne - nepheline, Hy -hypersthene, Ol -olivine, Di -diopside, Ac -acmite. Mg# (Mg number) defines the value for (MgO/(MgO+FeO))*100. Rock names are given according to the TAS (Total Alkali vs Silica) plot, after Le Bas et al., 1986. Age data are in unit of Ma (million of years), deteremined by the 40 Ar/ 39 Ar method (Wilch, 1997). 47

Fig. 19. CIPW normative plots (wt%) (after Cross et al., 1902) of lavas from the Crary Mountains, showing a distribution trend from strongly nepheline normative (silica- undersaturation) to quartz normative (silica-oversaturation) compositions. None of the Crary Mountains samples fall within the plane of silica saturation (Ol-Di-Hy). Abbreviations: Ne- nepheline, Di- diopside, Ol-olivine, Hy-hypersthene, Q-quartz. with decreasing MgO content (Fig. 20). The progressive change in whole-rock chemistry is broadly consistent with differentiation by early fractionation of olivine, clinopyroxene, and plagioclase (decreasing MgO and CaO) and complimentary enrichment in Na 2O, K 2O and Al 2O3 of the residual liquid and later fractionation of titanomagnetite and apatite (decreasing TiO 2,

P2O5).

The basalts from the Crary Mountains are not considered to be primary mantle melts. The

Mg#s for basaltic rocks from the Crary Mountains vary from 43 to 66 and the average Cr and Ni concentrations are below 150 ppm, indicating a significant loss of olivine and clinopyroxene during early stage differentiation (Panter et al., 2000).

The intermediate compositions (mugearite, benmoreite, and tephriphonolite) are characterized by lower MgO (1-4 wt.%) and higher Na2O concentrations (6-7 wt.%) with respect 48

a b

c d

e f

5 g h 4

0 0 5 10

Steere and Rees Other Crary Mountains

Fig. 20. Harker variation diagram showing compositional variation (wt.%) in lavas from the Crary Mountains. MgO is used as an index of differentiation.

49 to mafic rocks (Fig. 20). The FeO content in mugearite varies from 11 wt.% to 13 wt.%, which is higher than FeO content of benmoreite and tephriphonolite values. Benmoreite and tephriphonolite have very similar chemical compositions, although tephriphonolite is more silica-undersaturated and has higher alkali content (Na 2O+K 2O).

t The trachytes are comenditic (K-rich, high Al 2O3 wt.% and low FeO wt.%) and are subdivided into nepheline normative (3-6 wt.%) and quartz normative (1-8 wt.%) types (Table 8 and Fig.3). Quartz normative trachytes ( Qtz -trachyte) have MgO concentrations that vary from 0 to 1 wt.%, while the MgO content of nepheline normative ( Ne -trachyte) trachyte are slightly higher and vary from 1 to 3 wt.%. Trachytes and rhyolites have the lowest Mg#s, particularly in rhyolite where MgO is below the detection limit. Nevertheless, phonolite samples display nearly as much variation with respect to the other major elements as do the trachytes with the exception of Al 2O3. The phonolites are classified as high alkali (Na 2O + K 2O <15.47) and low alkali (Na 2O

+ K 2O > 13.46 wt%) phonolites. The Al 2O3 content does not vary greately for these phonolites.

The Al 2O3 content varies 13-17 wt% in trachytes to 17-19 wt% in phonolite (Fig. 20).

Lava compositions from Mt. Steere and Mt. Rees show abrupt changes with stratigraphic height (Fig. 2). Stratigraphic sections in the northern portion of Mount Steere consist of both silica-undersaturated and silica-oversaturated rocks, including Qtz -trachyte lava, which deposited on top of Ne -trachyte lavas (Fig. 2a). The central part between northern Mt. Steere and Lie Cliff is dominated by silica-oversaturated rocks, with rhyolite as the dominant composition. The major element concentrations in rhyolite change with stratigraphic height with the lower lavas having higher SiO 2 and K 2O and lower Al 2O3 and Na 2O contents relative to the upper flows. In the central portion of the Lie Cliffs the lower lavas of hawaiite are more mafic (higher in MgO wt.%) than upper hawaiite flows. Also, phonolites in the lower portion of the section have higher 50

SiO 2 and FeO and lower Al 2O3, Na 2O and K 2O relative to the upper flows. Overall, the Lie Cliff section shows a progressive chemical evolution with time. The bottom lavas are more mafic

(higher MgO, FeO and CaO contents) and the upper lavas are more felsic (higher SiO 2, K 2O and

Na2O contents) (Fig. 2a).

Trace Elements

Highly incompatible elements like La, Th, and Nb increase in concentration with increasing Zr, while Sr, Ni and Cr decrease with increasing in Zr (Fig. 21). The Zr/Nb ratios are nearly constant (~3.4) for the whole series from basanites to rhyolite (Fig. 22).

The mafic rocks of the Crary Mountains are characterized by having higher concentrations of compatible elements (e.g., Cr, Ni, Sr, Co) and lower concentrations of incompatible elements (e.g., Zr, Rb, Th) relative to intermediate compositions (Table 8). The trace element characteristics of mafic samples (basanite and alkali basalt) from the Crary

Mountains are thoroughly discussed by Panter et al. (2000). They found that the basalts are enriched in light rare earth elements (LREE) relative to heavy rare earth elements (HREE), which is characteristic of intraplate alkaline magmas worldwide. In mafic rocks (La/Yb) N (the ratio is normalized using primitive mantle values for lanthanum through ytterbium from Sun and

McDonough, 1989) varies from 9.7 to 13.7, indicating that they were derived by low degrees of partial melting. Systematic depletions in Cr, Ni and V suggest that olivine and clinopyroxene were fractionated during an early stage of magma differentiation (Panter et al., 2000).

Lavas of intermediate composition have lower concentrations of Cr, Ni, Co, Sr, and Sc and higher concentrations of La, Zr, Rb, and Th relative to mafic rocks (Table 8). Some intermediate samples have high Ba concentrations relative to mafic and felsic rocks (Fig. 21c). 51

a b

c d

e f

g Rees and Steere Other Crary Mountains

Fig.21. Trace element Zr (ppm) used as an index of differentiation vs. Cr+Ni, Ba, Sr, Nb, La, Th, and Y (ppm) plots for lavas from the Crary Mountains. 52

500

Rees and Steere 400 Other Crary Mountains

y= 2.254E-01 x + 8.782 r2=.94 300 Nb 200 Zr/Nb~3.4

100

0 100 300 500 700 900 1100 Zr Fig. 22. Zr (ppm) vs. Nb (ppm) diagram plotting lava samples from the Crary Mountains.

200

Ne -trachyte Sr

Qtz -trachyte 0 0 1000 2000 Ba Fig. 23. Ba (ppm) vs. Sr (ppm) plot of trachyte lavas from the Crary Mountains. Plot shows clear separation in composition between Qtz -trachyte and Ne -trachyte. 53

1000

100

1 Qtz -trachyte(TW92-006) Rock/Primitive Mantle Rock/Primitive .1 Ne -trachyte (TW92-109)

.01 CsRbBaTh U Nb K LaCePb Pr Sr P Nd ZrSmEu Ti Dy Y YbLu Fig. 24. Primitive mantle-normalized trace element plots of two different types of trachytes ( Ne - trachyte and Qtz -trachyte) from Mount Rees. Normalization values from Sun and McDonough, 1989). TW92-006 – Qtz -trachyte, and TW92-109- Ne -trachyte. P is below detection limit for Qtz -trachyte.

Phonolites, trachytes, and rhyolites are highly enriched in incompatible elements (e.g.,

Zr, Nb, La, Th) relative to mafic and intermediate compositions as is usual. Zirconium concentrations vary from 460 to 1092 ppm (Table 8) with the greatest variation in trachytes. The

Qtz -trachytes have similar trace element concentrations as rhyolites, whereas, Ne -trachytes are much more similar to the high silica-low alkali phonolites. The alkaline mafic rocks (basanite and hawaiite) from Mt. Steere and Mt. Reese are enriched in Sr and Ba with respect to the other mafic alkaline rocks in the Marie Byrd Land province. However, the Ba contents of two trachyte samples (TW92-053 and TW92-109) are higher than in any other Crary Mountains lava measured (Fig. 21c) (>2000 ppm). The Qtz -trachytes have higher overall incompatible element concentrations relative to Ne -trachytes except for the elements Ba and Sr (Fig. 23 and 24). 54

However, both trachyte types are depleted in Sr and Ti content with respect to mafic and intermediate rock types indicating the fractionation of feldspar and titanomagnetite. Both types of trachytes are characterized by high large ion lithophile element (LILE) / high field strength element (HFSE) ratios (e.g., K/Nb = 4.5 to 7.9). The two rhyolite lavas (TW92-093 and TW92-

183) show some differences in trace element concentrations (Table 8). For example, the high silica rhyolite (SiO 2 = 72.65 wt.%) is enriched in Zr and depleted in Ba with respect to low silicate rhyolite (SiO 2 = 68.15 wt.%). Some phonolites have lower Th and Yb concentrations relative to other felsic compositions. The Ba and Eu contents in phonolites are also depleted relative to other felsic rocks.

The changes in composition with stratigraphy as described for major elements show corresponding changes in trace element concentrations. For example, in the northern part of

Mount Steere the Qtz -trachyte lavas found at the base of the stratigraphic section have higher concentrations of Sr, Cr, Ba, and Ni and lower concentrations of Rb, La, Ta, and Zr relative to the overlying Ne -trachytes and the overall progressive geochemical change indicated by major elements from lavas in the Lie Cliff stratigraphic sections is confirmed by changes in trace element contents.

DISCUSSION

The compositional diversity of the rocks and the long period of activity that erupted lavas and volcaniclastic rocks from multiple centers in the Crary Mountains indicates a long-lived and complex magma system. There is evidence for systematic compositional change with the migration of activity towards the south, compositional changes with time at individual centers are revealed in the stratigraphy of Mounts Rees and Steere. The compositions change from mafic to felsic and felsic to mafic in a stratigraphic section of Mount Steer and Mount Rees; however, in a broad sense the overall composition of the Crary Mountains change towards more mafic with time. All of this would suggest that the evolution of the Crary Mountain lavas can not be modeled as a simple, single evolving magma system. Therefore, to produce a simplified petrographic model I assume that all these magmas are generated from a single source and evolving from basanite to towards phonolite and trachyte. Mineral chemistry and major and trace element data, were used to evaluate magmatic differentiation processes such as fractional crystallization and assimilation of crust.

Magmatic Evolution by Fractional Crystallization

The trends of major and trace elements plotted against indices of differentiation (Figs. 3,

20, 21, and 25) indicate progressive differentiation dominated by fractional crystallization processes. Phenocrysts of olivine, clinopyroxene, plagioclase, and titanomagnetite occur in all basaltic samples of the Crary Mountains and the fractionation of these minerals can best explain the evolution of magmas to evolved mafic and intermediate compositions. Olivine fractionation is implicit based on the extremely good positive correlation between Ni and MgO (Fig. 21a and

25). Vanadium and Cr partition strongly into clinopyroxene (Lindstrom 1976), thus the fractionation of clinopyroxene is expressed by the decrease in concentration of V and Cr with 56 decreasing MgO content in Figures 21a and 25. In Figure 25 two trends are shown; a high-V and a low-V trend that merge when MgO values of the lavas are less than 4 wt.%. This may suggest that the magmas evolved from two different parental magmas or that the early fractionation of clinopyroxene (from V rich magma trend) was suppressed for some magmas. This clinopyroxene is also characterized by high Ti content, which can be supported petrographically (clinopyroxene phenocrysts in TW92-014). The decrease in the CaO/Na 2O ratio with decreasing MgO content suggests plagioclase and clinopyroxene fractionation (Fig. 20h). The decrease in TiO 2 (wt%) at

MgO less than 4 wt.% likely signifies a high amount of titanomagnetite being fractionated which is also supported by Figure 26a.

To test the feasibility of a fractional crystallization model for the evolution of mafic to felsic magmas rocks from the Crary Mountains, I employed the least-squares mass-balance model for major elements using the method described by Arth (1976). The models use bulk-rock analyses (Table 8) and the mineral composition determined by microprobe analysis (Table 9).

Trace element models are carried out with a Rayleigh fractionation scheme (Rayleigh, 1896) using the proportion of mineral phases determined by least-squares mass balance calculations and published mineral-liquid partition coefficients (K D) for alkaline assemblages (Table 10).

The Rayleigh distillation equation for closed system fractional crystallization is:

C = C F (D− )1 (after Cox et al., 1979) L 0

where CL is the concentration of the element in the residual liquid, C 0 is the initial concentration of the element in the liquid, F is the fraction of the liquid that remains, and D is the bulk partition coefficient for the crystallizing solids. The bulk partition coefficient ( D) is calculated using the equation: 57

b 01 01 Ol Fo78- 0.35 b 17- Cpx 46-37- 16.15 40.74 b Pl An92- 34.4 2.24 0.02 b Pl An75- 49.1 44.78 51 38.14 lected minerals from other alkaline rocks. rocks. otheralkaline from lectedminerals a a 3 3 0.98 0.63 10.83 20.82 .25 15.36 18.18 17.91 0.18 Sid- bas- Cpx 3 3 99.68 99.49 98.92 99.13 100.27 Cpx 174- TW92- 169-Ol 169-Ol TW93- 23-Mt 23-Mt TW92- AF AF 139- TW92- able 1.able ization models; compositions from thisand se study from compositions models; ization 014-Pl 014-Pl TW92- 23-Ap 23-Ap TW92- 23- Amp Amp TW92- 134- Amp Amp TW92-

12.62 11.15 - 31.01 20.77 2.24 0.05 0.68 0.67 31.1 - - 42.2 ------3.87 5.16 - - - 24.53 0.02 0.61 0.3 0 0 0.39 0.01 39.48 40.14 0.13 51.9 67.29 0.11 38.29 47.81 54.15 3 5 2 2 O 2.9 2.77 - 3.97 9.06 - - 0.5 0.26 2.72 0.84 0.2 0. Panter et al., al., Panter(2000). et Deer et al., (1996). Deer et al., O 0.78 O 0.93 1.95 1.97 - - 0.19 3.64 - - - 0.02 0.01 - - - 0.1 - 0.05 0 - 0 - - - - O 2 O 2 2 2

2 FeO FeO 18.1 16.81 0.29 0.89 0.11 66.71 23.65 27.86 2.7 K H Sum 99.59 99.76 101 100.91 101.64 96.13 100.44 99.0 CaO 10.95 11.33 53.78 12.68 0.69 0.01 0.25 19.83 24 SiO TiO P MgO MgO 8.61 9.16 - - - 1.57 37.87 0.76 17.16 0.13 0.04 MnO MnO 0.29 0.33 0.06 - - 0.96 0.26 0.99 0.16 0 0 0.41 Na Al a- b- CODE CODE 1 2 4 6 8 10 12 20 23 29 31 37 41 Sample

Table 9.- Mineral data used for Fractional crystall forMineral used Fractional 9.- data Table The abbreviations for minerals are the same T as in the same are for minerals The abbreviations 58

HPP Alkali Feldspar MA with additional values values additional with a a 0.95 0.13 - Apatite

, 1981). , 1981). a a nter et al. (1997) al. et nter 0.09 0.014 3.02 5.04 0.44 0.56 0.42 - Nepheline

a a Amphibole

0.23 1.01 0.24 0.83 4.11 5.57 a a ). D aroff et al., 1993); HPP- Hut Point Peninsula (Kyle Hut Peninsula Point HPP- 1993); al., aroff et ent ent (K 1993), Kyle (1981), Larsen (1979) as compiled by Pa by compiled as (1979) Larsen Kyle (1981), 1993), 0.65 0.57 0.03 0.15 2.08 0.043 14.5 1.78 1.72 Clinopyroxene Clinopyroxene Olivine Magnetite 40 a a 0.03 2.39 2.65 0.2 5.04 7.58 0 0.41 0.22 - 1.08 0.07 0.04 0.04 0.14 0.56

a Plagioclase~An 65 ~An

Sr Sr 2.12 4.41 0.33 0.16 0.01 Sc 0.02 La La 0.12 0.46 0.22 0.1 0.02 0.53 0.56 0.01 15.2 0.46 0.219 Hf Ta 0.01 0.01 0.15 0.08 0.69 0.14 0.43 0.04 0.05 0.03 1.77 3.86 0.8 0.89 0.008 0 0.64 0.13 0.09 0.12 - - Tb Tb Lu 0.03 0.18 Th 0.23 0.02 0.11 0.77 0.73 0.7 0.16 0.7 0.04 0.13 0.55 0 0.03 0.04 2.88 0.75 0.53 0.014 1.77 19.8 0.09 0 0.23 0.01 0.130 3.4 0.11 - Ce Ce 0.14 0.36 0.34 0.2 0.001 0.56 0.87 0.011 16.6 0.36 0.173 Eu Eu 0.22 1.78 Ba Ba 0.215 Rb 0.03 0.2 0.1 0.04 0.08 0.23 0.12 Yb 0.11 0.18 0.73 0.7 0.001 0.75 1.77 0.016 9.4 0.18 0.116 Nd 0.07 0.31 0.68 0.6 0.001 0.55 1.82 0.013 21 0.31 0.152 Sm 0.12 0.27 0.66 0.6 0.001 0.55 2.4 0.012 20.57 0.27 0.139

from LeMarchand et al. (1987). MA- Mururoa Atoll (C Mururoa Atoll MA- (1987). al. et LeMarchand from Table 10. Published mineral/melt partition coeffici partition mineral/melt Published 10. Table ( al. Caroff et are from coefficients The partition 59

D = ∑ wi K D (after Cox et al. 1979) i i−1 where w is weight proportion of each mineral determined by least-squares mass balance.

The results of the model calculations are given in Tables 11 through 18 and Figures 27 through 29. For the major elements, the parent composition is estimated by adding minerals back to the daughter whole-rock compositions in the proportions determined by mass balance.

Trace elements are calculated to compare with measured parent compositions. A total of four fractionation lineages are tested and the predicted evolutionary paths are shown in Figure 26b.

Ne-Trachyte Series

Least-squares mass balance modeling can successfully predict the evolution of basanite to produce Ne -trachyte (Table 10, models A-D). Basanite sample TW92-059 is chosen to represent the parent magma for the Ne -trachyte series. The sample is characterized by relatively high MgO, CaO, Cr and Ni content with respect to other mafic rocks of Mount Steere and Rees.

The mineral assemblage in each model was carefully selected to match the natural modes observed in the lavas. Differentiation of basanite by the fractionation of diopside, olivine, plagioclase, and titanomagnetite leaves 73% residual liquid of a hawaiite composition (Model

A). Further differentiation of hawaiite by fractionation of a similar mineral assemblage, but in slightly different proportions, can produce mugearite (Model B, ~46% residual liquid). 60

400

300

200 V

100

0 0 5 10 MgO Other Crary Mountains

Rees and Steere

Fig. 25. V (ppm) vs. MgO (wt%) plot of the lavas from the Crary Mountains.

Fig. 26 a. Distribution of Sm (ppm) vs TiO 2 (wt%) for the rocks of Mount Steere and Rees. 61

16 122 s 14 ie 36 r e s s ie r e e it 12 s l o 109 91 te n li o o h 93 n P Qtz-trachyte series 10 o h 23 P O 2 s 8 e ri O+K 169 e 2 82 s te y Na 6 h c 1 ra -t e 4 59 N

0 35 40 45 50 55 60 65 70 75

SiO 2 Fig. 26 b. TAS diagram shows the trend of proposed four different evolutionary lineages via fractional crystallization models for the production of different magma types in the Crary Mountains. All of the sample names are started with “TW92-“.

Continued differentiation of mugearite by the fractionation of a similar mineral assemblage with the addition of apatite produces benmoreite (Model C, ~29% residual liquid) and the fractionation of alkali feldspar, amphibole, and apatite produce Ne -trachyte (Model D, ~19% residual liquid). Model values of Σr2 ≤ 1 are considered to offer a satisfactory match between calculated and measured concentrations for major element oxides.

The results for trace elements based on Models A-D (Table 11) are given in Table 12.

The error between measured and calculated values for the majority of the elements in Models A and B are less than 20% and less than 40% for Model C. The calculated trace element concentrations in Model D match measured values for only a few elements (e.g., Sr, La, Ce, Lu and Hf) (Fig. 27). 62

The trace element model for the Ne -trachyte work pretty well from Model A to Model C; however, the mismatches started to do occur in Model D. The calculated bulk distribution coefficient for Eu in Models A through C in Table 12 is 0.1; incompatible with respect to the fractionating assemblage including plagioclase. Therefore, the residual liquid becomes enriched in Eu. The high variability of the experimentally derived KD values for different minerals might be, in part, responsible for the mismatch for elements Sc, La, and Yb (Price et al., 2003). In

Model D, some of the trace elements do not match measure values, especially for Ba. The calculated values of the Ba are higher than measured values. The one reason for this over- estimation is the high D value related to the high amount (20%) of alkali feldspar fractionated.

Lower amounts of alkali feldspar would decrease the D for Ba and provide a better match. This is supported by the fact that the calculated K 2O concentration is higher than the measured value, which indicates that too much alkali feldspar is being added back to the daughter composition.

In Model C the mismatch between measured and calculated values for the heavy rare earth elements (HREE) and middle rare earth element (MREE) is probably due to the amount of mineral phases (e.g. amphibole and apatite) used for the fractionation model might not be similar in amount as the actual process. For example, the fractionation of higher amount of amphibole can lead to depletion in MREE in the residual liquid. In Model C it is observed that MREEs and

HREEs are lower than the measured values, which is a result of the low D values generated by this model. The fractionation of more clinopyroxene and amphibole would be required to better match REEs. Also, Y, Nb, and Ta are compatible in apatite; therefore, it might be possible that greater amounts of fractionation of this mineral (Model C) could lead to a better match between calculated and measured values, although that might lead to a poor fit for P 2O5 for the least square model. In all these models the fractionation assemblage chosen is based on petrographic 63

R Σ 0.15

O 2 0.30 0.30 0.29 0.48 0.52 0.55 0.89 0.19 0.81 0.32 0.43 0.43 P

2 .98 .98 0.66 0.66 0.64 1.02 1.24 1 1.82 2.77 3.59 K

O 2 2.87 2.87 2.77 4.23 3.60 4.94 5.19 6.89 6.65 . . the code for each mineral used for for used mineral each for the code

9.46 9.46 9.39 7.27 7.35 4.23 4.19 CaO CaO Na 11.73 11.66

6.09 6.09 4.69 4.61 2.85 2.94 1.28 1.77 6.11 MgO

0.20 0.20 0.26 0.24 0.27 0.37 0.23 0.21

FeO FeO MnO 7.79 7.79 7.59 14.05 13.91 14.26 14.31 12.88 0.28 12.79

3 pt(4)) O 02Ol(41)+0.04Mt(10)) 02Ol(41)+0.04Mt(10)) 2 3Ol(12)+0.07Mt(10)) 3Ol(12)+0.07Mt(10)) 7Ol(41)+0.04Mt(10)+0.01Apt(4)) 7Ol(41)+0.04Mt(10)+0.01Apt(4)) Al

2 -trachyte series, Crary Mountains, Antarctica Mountains, Crary series, -trachyte Ne 3.05 16.79 3.37 16.68 3.56 16.19 3.47 16.17 2.54 15.97 2.63 15.51 1.18 19.10 1.17 18.93 TiO thesis following each mineral-0.18Pl(31) indicates indicates mineral-0.18Pl(31) each following thesis 2

44.27 44.27 44.33 45.87 46.38 50.41 50.59 56.22 57.44 ls for the the ls for SiO

Calc. Calc. Calc. Calc. Meas. Meas. Meas. Meas. Meas. Meas. Meas. TW92-059= 0.73*TW92-001+ (0.18Pl(31)+0.13Cpx(37)+0. 0.73*TW92-001+ TW92-059= TW92-023=0.63*TW92-109+ (0.20Af(8)+0.16Amp(2)+0.01A TW92-023=0.63*TW92-109+ - In each equation the number enclosed within paren within enclosed number the equation each In - (TW92-082) Hawaiite (TW92-001)-Mugearite B. (0.19Pl(29)+0.08Cpx(23)+0.0 TW92-001=0.63*TW92-082+ Ne-Trachyte Series Ne-Trachyte (TW92-001) (TW92-059)-Hawaiite A.Basanite

D. Benmorite (TW92-023)-Ne Trachyte (TW92-109) (TW92-023)-Ne D.Benmorite (0.13Cpx(20)+0.11Pl(29)+0.0 TW92-082=0.64*TW92-023+ C. Mugearite (TW92-082)-Benmorite (TW92-023) (TW92-023) (TW92-082)-Benmorite C.Mugearite Table 9. 9. Table Table-11. Fractionational crystallization (FC) (FC) mode crystallization Fractionational Table-11. Note

023 to (0.63)109 D Ben-Ne Trach *100. *100. 9.3 6.7 37.6 0.3 2 4.1 3.7 10.2 0.4 2 7.2 7.1 2.0 0.3 6 10.3 10.2 1.0 0.4 1 3.1 7.1 66.5 6 2.2 1.0 1.0 4.9 0.9 .3 4.1 6.4 35.3 1.1 .1 10.3 18.0 43.8 1.7 .6 9.3 6.3 31.7 0.5 0.2 14.4 8.8 38.6 0.1 values (Table 10). All sample No.’s begin begin No.’s sample 10). All (Table values D 5 0.2 47.3 41.8 13.2 0.4 .5 0.1 59.8 87.4 32.2 1.5 2.4 0.0 54.6 61.1 11.9 0.3 2.4 0.1 94.8 86.6 8.7 0.8 12.4 1.5 6.2 19.4 68.1 3.5 Error% D Meas.109 Calc. Error% D 10.0 0.1 171.1 174.8 2.2 1.0 98.1 27.2 0.6 477.3 486.2 1.9 2.7 23.9 8.7 0.1 789.6 1865.5 58.3 1.9 082 to (0.64)023 C Mug-Ben odels (Table 11) calculated using published K published using calculated 11) (Table odels n used for calculation Error%=((Calc.-Meas.)/Calc.) for calculation used n .001 Calc. Error% D Meas. 023 Calc. 001 to (0.63)082 B Haw-Mug - Trachyte Series Y 21.6 20.4 5.6 0.1 31.0 31.8 2.6 0.1 49.2 33.2 32. Sr 606.3 649.8 7.2 0.9 685.5 532.0 22.4 0.9 547.0 3 Er 2.1 2.0 1.0 0.1 3.1 2.7 14.5 0.1 4.1 2.9 28.3 0. Sc 26.8 21.6 19.4 1.3 18.6 11.2 39.8 1.0 41.0 35.9 La 22.6 25.0 10.6 0.1 38.3 43.1 12.5 0.1 Hf Ta 65.6 3.0 1.9 64.0 3.7 2.1 21.7 12.1 0.5 0.5 4.8 3.4 4.8 4.5 1.7 33.0 0.5 0.8 6.1 5.0 8.5 7.3 40.4 47.1 0. 0 Ce 46.3 50.1 Eu 8.2 1.0 0.1 1.4 76.5 32.0 84.8 0.1 Lu 10.9 2.1 0.2 0.1 0.3 129.1 2.0 116.2 17.4 3.4 0.3 0.1 0.4 3.1 0.4 2.1 30.6 20.0 0. 0.4 0.6 0.5 5.4 0. Ba 190.4 197.2 3.6 0.1 309.2 370.4 19.8 0.1 573.7 5 Th 2.3 2.6 13.3 0.1 4.1 5.1 26.0 0.1 7.7 10.2 32.0 Rb 13.4 13.6 1.5 0.0 21.7 25.9 19.4 0.0 41.0 35.9 1 Nd 21.6 22.4 Gd Dy 3.7 4.1 4.1 0.1 4.1Yb 34.1 3.4 2.1 1.0 34.8 17.5 1.4 0.2 0.1 2.1 34.0 6.2 5.2 0.1 0.1 6.0 53.3 5.3 2.1 40.8 3.1 2.9 23 2.7 0.1 0.1 28.0 9.2 8.2 0.1 6.4 4.1 5.1 30.4 38.4 3.0 0.2 0. 25.9 0 Sm 4.1 4.8 15.3 0.1 7.2 6.7 7.7 0.1 10.2 7.1 30.7 0 A Bas-Haw 059 to (0.73)001 Meas. 59 Calc. Error% D Meas Ne Table 12. Trace element solutions (in ppm) for FC m ppm) (in solutions Traceelement 12. Table The equatio Note. coefficient. Distribution Bulk D= with the prefix ‘TW92-’. ‘TW92-’. the withprefix 65 analysis, however, it may be possible that some minerals on the liquidus are not adequately represented in thin section.

1000 1000

Measured

100 Calculated 100

10 10

Concentration (ppm) Concentration Model B

Concentration (ppm) Concentration 1 1 Model A

0.1

0.1 Y Hf Sr Er Lu Th La Yb Ta Sc Eu Dy Rb Ba Nd Ce Gd Sm Y Hf Sr Er La Lu Yb Ta Th Sc Ba Nd Eu Dy Rb Ce Gd Sm

1000 10000

1000 100

100 10

10 Concentration (ppm) Concentration 1 Model C Concentration(ppm) 1 Model D

0.1 0.1 Y Y Hf Sr Er Lu Th La Yb Ta Sc Eu Dy Rb Ba Nd Hf Ce Gd Sr Er Lu Th La Yb Ta Sm Sc Eu Dy Rb Ba Nd Ce Gd Sm Fig. 27. Observed and calculated trace element values for Ne -trachyte series (used in Table 12).

Phonolite Series

Two different models of fractional crystallization are proposed that might lead to production of phonolitic rocks; one model describes the fractional crystallization of benmoreite, to phonolite and the other tephrite to phonolite. The major and trace element results for these models are presented in Tables 13-16.

The fractionation of alkali feldspar, amphibole, apatite and magnetite from benmoreite produces 35% phonolite (sample TW92-036, a low alkali-high silica variety, Table 13). The Σr2 for both models are ~1, which is acceptable. The trace element model provides a reasonable match with the measured values (Fig. 28, Model A) except for Rb, which shows an error of 48% 66

2 R Σ

5 O 2 0.32 1.01 0.71 P

O 2 2.77 2.77 3.12 K

O 2 values (Table 10). All sample No.’s sample All 10). (Table values A) from theCrary Mountains, from A) 6.89 7.26 D

d K d es the code for each mineral used for used each for mineral the code es 4.23 4.23 3.84 CaO CaO Na

1.28 1.89 MgO

0.23 0.23 0.15

FeO FeO MnO 7.79 7.43

3 Ap(4)+ 0.02Mt(10) Ap(4)+ O 2 Al

2 te (TW92-036) 1.18 1.18 19.10 1.37 18.23 ls for the low alkali low for high alkali the (Model ls silica phonolite TiO 2 Coefficient. Coefficient. arenthesis following each mineral-0.41Af(8) indicat mineral-0.41Af(8) each following arenthesis odels (Table 13, Model A) calculated using publishe using calculated ModelA) (Table13, odels 56.22 56.16 Error% Error% D Mea. to (0.66)36 23 Mea. SiO Calc. Calc. Meas. Meas. Low Phonolite SeriesAlkali-HighSilica Low Meas. Meas. Calc. Sr Sr 477.3 387.6 19 2.83 Sc Sc 6.19 5.83 6 3.13 Hf Hf Ta 10.3 9.28 7.68 6.84 25 26 0.43 0.51 Ba Ba 789.6 581.2 26 2.03 Lu Lu 1.03 0.74 28 0.76 Ce 171.1 186.3 9 0.56 Th 14.4 9.50 34 0.13 Eu Tb 30.9 1.03 3.23 1.72 90 40 1.85 1.24 Rb 54.6 80.6 48 0.31 Nd Nd 59.8 71.3 19 0.89 Yb Yb 4.12 3.64 12 0.80 La La 94.8 106.0 12 0.50 Sm 10.3 12.4 20 1.08 TW92-023= 0.35*TW92-036+ (0.41Af(8)+0.19Amp(2)+0.03 TW92-023=0.35*TW92-036+ Note- In each equation the number enclosed within p within enclosed number the each equation In Note- Table 9. 9. Table m for FC (in ppm) solutions element Trace14. Table Antarctica. Antarctica. Table-13. mode Table-13. crystallization (FC) Fractionational Phonolite Alkali-HighSilica Low Series (TW92-023)-Low Benmorite Phonoli Alkali-HighSilica Distribution Bulk D= ‘TW92-’. theprefix beginwith

2 R Σ

5 O 2 0.86 0.95 0.03 P

O 2 K

O 2 values (Table 10). All sample No.’s No.’s sample All 10). values (Table D d K d CaO Na B) from theCrary Mountains, Antarctica. Antarctica. Mountains, theCrary from B)

MgO

0.22 5.19 0.29 8.24 5.00 5.07 7.72 1.65 4.57 1.39

FeO FeO MnO

O Cpx(20)+ 0.01Mt(10) 2 Al

2 e (TW92-122) (TW92-122) e 3.46 16.54 3.37 13.44 17.06 14.01

TiO 2 lc.-Meas.)/Calc.)*100. lc.-Meas.)/Calc.)*100. Coefficient. Coefficient. odels (Table 15, Model B) calculated using publishe using calculated B) odelsModel 15, (Table ls for the high alkali low silica phonolite (Model (Model phonolite silica low alkali thefor high ls SiO Calc. Calc. 46.33 169 169 to (0.77)122 Meas. 45.33 High Alkali-LowHigh Silica Phonolite Series TW92-169= 0.35*TW92-122+ TW92-169= (0.41Pl(6)+0.12Ol(12)+0.11 Meas. Calc. Error% D Sr Sr 892.1 511.1 43 1.26 La La 51.5 57.1 11 0.17 Ba Ba Ce 476.3 Th 103.9 267.3 6.05 101.0 44 11.1 3 0.16 45 0.20 0.10 Rb 35.3 52.3 33 0.07 Nd Nd 46.4 27.4 41 0.21

Table-15. Fractionational crystallization (FC)mode crystallization Fractionational Table-15. Alkali-LowHigh Silica Phonolite Series (TW92-169)-High SilicaTephrite Alkali-Low Phonolit for m FC (in solutions ppm) element Trace 16. Table Error%=((Ca calculation for The used equation Note- begin with the prefix ‘TW92-’. D= Bulk Distribution Bulk D= ‘TW92-’. prefix the beginwith

Fig. 28. Observed and calculated trace element values for Phonolite series. Fractional crystallization (FC) models given in Tables 14 and 16.

(Table 14). This might be due to high fractionation of amphibole from the melt. Terbium (Tb) always behaves as compatible elements with respect to amphiboles. Therefore, a high degree of fractionation of amphibole leaves residual melt depleted in Tb relative to the parental magma.

On the other hand, REE are compatible in apatite. Therefore, a relatively high amount of apatite fractionation from the melt will leave the residual melt depleted in these elements.

Approximately 3% of apatite was fractionated in Model A. The calculated bulk distribution (D) values for the REE in Table 16 vary from incompatible (La, Ce, Nd) to compatible (Sm, Eu, Tb) back to incompatible (Lu). This is difficult to reconcile based on the mineral assemblage chosen for this model.

Model B (Tables 15 and 16, Fig. 28 Model B) considers alkali-rich basalt (tephrite sample TW92-169) as a parent to a high alkali-low silica variety of phonolite (sample TW92-

122). Plagioclase, olivine, clinopyroxene, and magnetite are fractionated from tephrite to produce 35% residual phonolite. The Σr2 is ~1, which is acceptable. The calculated trace elements poorly fit measured values for most of the elements calculated (Fig. 28, Model B), with errors ranging from 3 to 45% (Table 16). There may be several reasons for this poor match; 1)

This suite exhibits an apparent “Daly Gap” and intermediate compositions and associated 69 minerals were not modeled, 2) the expected changes in behavior for individual elements with magma evolution are not considered, 3) parent and daughter compositions may not be appropriate for this model. However, the close match of the least square model indicates that fractional crystallization might be a possibility for this type of phonolite production.

Qtz-Trachyte Series

The derivation of silica-oversaturated magmas from silica-undersaturated magmas by closed system fractional crystallization is considered here using the same modeling techniques outlined in the previous section. I will attempt to model Qtz -trachyte from a Ne -trachyte parent by fractional crystallization. Sample TW92-109 ( Ne -trachyte) is the least fractionated rock in the nepheline normative trachyte series and is selected as a potential parent for the derivation of Qtz - trachyte (TW92-091). The fractional crystallization model is given in Table 17. As with the previous models (Table 11) the selected fractionated mineral assemblage was selected to agree with the minerals identified in the samples. Model A (Table 17) calls for the fractionation of

47% alkali feldspar, 9% amphibole, and 4% titanomagnetite from Ne -trachyte to produce 40%

Qtz -trachyte. Further fractional crystallization of alkali feldspar and magnetite from Qtz -trachyte

(Table 17B) leads to the production of 32% rhyolite residue (TW92-093). The Σr2 for both models are ~1, which is acceptable.

The trace element results for Models A and B are given in Table 18 and Figure 29. Apart from a few of the highly incompatible elements (Rb, Sr, Ba, Th), Model B provides a satisfactory explanation for the evolution of Qtz -trachytes to rhyolites. However, overall there is a poor quality fit between calculated and measured values in Model A (errors 45-69%) with the calculated values being lower than measured values (Fig. 29). The calculated trace element concentrations have lower MREE and HREE concentrations relative to the measured 70

R Σ

5 O ca. ca. 2 0.10 0.10 1.03 0.01 0.03 1.02 0.00 P

O 2 4.33 4.33 3.97 5.30 4.82 K

es the code for each mineral for mineral each code esthe O 2 7.03 7.03 6.88 6.17 5.82

2.67 2.34 1.50 1.47 CaO CaO Na

0.36 0.36 0.10 0.06 MgO

0.24 0.12 0.79 0.19 0.15

Mt(10)) Mt(10)) FeO FeO MnO 7.50 7.50 7.47 5.53 5.27

3 -trachyte series from the Crary Mountains, Crary Antarcti the from series -trachyte O 2 Qtz Al

2 W92-091) W92-091) W92-093) W92-093) 0.48 0.48 17.52 0.75 16.79 0.34 15.03 1.08 14.97 arenthesis following each mineral-0.47Af(8) indicat mineral-0.47Af(8) each following arenthesis ls for the for ls TiO 2 59.77 60.83 65.80 66.36 SiO

Calc. Calc. Calc. Meas. Meas. Meas. Meas. TW92-109= 0.40*TW92-091+ (0.47Af(8)+0.09Amp(2)+0.04 0.40*TW92-091+ TW92-109= Table-17. Fractionational crystallization (FC) mode (FC) crystallization Fractionational Table-17. Series Qtz-Trachyte (T (TW92-109)-Qtz-Trachyte Trachyte A.Ne-Normative (T (TW92-091)-Rhyolite Trachyte Quartz Normative B. (0.16Af(8)+0.03Mt(10)) TW92-091=0.81*TW92-093+ p within enclosed the number equation each In Note- 9. Table for used

*100. *100. values (Table 10). sample All values (Table D odels (Table 17) calculated using published K published using 17) calculated (Table odels Calc. Error% Error% D Calc. n used for calculation Error%=((Calc.-Meas.)/Calc.) usedfor n 091 to (0.20)093 (0.20)093 to 091 B B 28 28 2.45 377 944 60 2.50

1445.5 109 to (0.61)091 to 109 (0.61)091

-trachyte Series -trachyte No.’s begin with the prefix the begin with No.’s ‘TW92-’. Qtz Table 18. Trace m FC 18.Trace element for solutionsppm) (in Table A D 59 Calc. Meas. Error% Meas.001 Sc Rb 6.09 Sr 84.2 1.86 Ba 227.4 73.4 2002.7 La 69 234.4 Ce 13 93.4 1.66 3 Nd 178.6 0.37 52.9 1.01 Sm 101.1 3.36 71.1 132 1.81 Eu 43 13.2 43 26.2 42.5 178.6 Tb 4.06 79 0.48 8.38 0.45 68.4 40 Yb 35 2.03 168.3 85.7 5.8 37 Y 0.45 62 6.09 0.55 172.4 1.45 0.36 92.2 Lu 0.60 43 3.65 64.5 3.40 2 Hf 29 - 1.02 12.1 7 63.7 1.70 40 Ta 0.64 13.2 0.58 12.1 0.33 Th 3.02 0.46 0.41 1 8.12 - 2.02 5.52 43 2.25 0 13.2 6.05 3.58 1.72 The equatio distribution Note. coefficient. Bulk D= 58 0.30 0.40 5.98 26 5.97 - 56 0.26 15 0.35 1.01 55 1.47 1 0.51 10.1 0.84 0.23 - 0.15 6.05 11.8 0.19 17 13.1 66.5 6.79 17 19.4 0.13 66.9 12 0.15 48 1 0.17 0.14 0.04 72

10000.00 1000

Measured

1000.00 Calculated 100

100.00 10

10.00 Concentration (ppm) Concentration Concentration (ppm) Concentration 1 1.00 Model A Model B

0.10 0.1 Y Y Hf Sr Lu Th Hf La Tb Yb Ta Sr Sc Eu Lu Th Rb Ba Nd La Tb Yb Ta Ce Sc Eu Rb Ba Nd Ce Sm Sm Fig. 29. Observed and calculated trace element values for Qtz -trachyte series (used in Table 18).

concentrations. The choice of parent and daughter or the choice of fractionation assemblage may be responsible for the poor match. The D values used for this model are mostly less than 1

(except Sc, Sr, Ba and Eu) resulting in a calculated concentration that is less than the measured values. Higher D values might reduce the difference between calculated and measured trace element concentration in this model; however, that might not be realistic. However, a second possibility might be that the appropriate K D values for amphibole may not have been used in this model. The experimentally derived K D’s of REEs and HFSE for amphibole are extremely variable. For example, K D value of Eu for amphiboles in trachytic rocks vary from 1.08-2.08

(Klein et al., 1997); for Lu from 0.89 to 1.77 (Nagasawa 1973) and for Ta from 0.56-0.98 (Klein et al., 1997). However, the most likely reason for the poor fit may be that closed system fractional crystallization does not adequately explain the evolution from one composition to another and that there might be other processes (e.g. AFC, magma mixing) leading to the production of silica-oversaturated magmas in the Crary Mountains.

Magmatic Evolution by Assimilation of Crust

The assimilation of crust by silica-undersaturated mantle derived melts and coincident fractional crystallization (AFC) has been used to explain the genesis of silica-oversaturated trachytes and rhyolites (e.g. Foland et al., 1993; Kabeto et al., 2001; Perini et al., 2004). In

Marie Byrd Land, Panter et al. (1997) called upon process to explain the origin of silica- oversaturated trachytes at Mount Sidley. However in another model involving silica- oversaturated compositions from Marie Byrd Land, LeMasurier et al. (2003) suggested that the fractionation of silica-undersaturated minerals (kaersutite and plagioclase) from a basaltic magma in the lower crust led to silica-oversaturation of residual liquid that eventually erupted at the surface.

Panter et al. (1997) considered that the high LILE/HFSE ratios of Qtz -trachytes relative to Ne -trachytes and phonolites may be a result of the ‘dilution’ of magmas by incorporating crustal sources that are depleted in HFSE relative to LILE. The authors proposed that the contaminant was calc-alkaline granodiorites of Devonian age. Although none of these

‘basement’ rocks crop-out at Mt. Sidley or in the Crary Mountains, they are found in the coastal

Marie Byrd Land, Edward Peninsula (Adams et al., 1995 and Weaver et al.,, 1992) and central

Ellsworth–Whitmore Mountains in West Antarctica (Mukasa and Dalziel, 2000) and when are inferred to exist below the volcanic edifices of central Marie Byrd Land in the middle to upper crust.

Geochemical variation and the origin of silica-saturated trachyte and rhyolite can be explained by the assimilation of granitic rocks from Marie Byrd Land with concurrent fractional crystallization (AFC). Al 2O3 rich clinopyroxene phenocrysts in phonolite also support this theory. 74

The AFC model has been studied in detail by DePaolo (1981) who considered the mathematical treatment using the equation:

o −Z r Ca −Z Cm / Cm = F + ( ) o 1( − F ) r −1 zC m

C o F where m is the concentration in the magma, Cm is the original concentration in the magma, is the mass of magma remaining as a fraction of the original magma mass, r is the ratio of mass assimilated to mass crystallized, and Ca is the concentration in the assimilated material, and Z is:

r + D −1 Z= r −1 whereas D is the solid-liquid bulk partition coefficient of the element.

Modeled AFC trends are calculated using a granodiorite contaminant (sample 212.3P) from

Edward VII Peninsula (Weaver et al., 1992) and a mugearite from Mount Steere (TW92-082).

The mugearite sample is also used as a parent composition for fractional crystallization models and both AFC and FC curves are plotted in Figures 30-32. The Nb/La and Sr concentrations predicted by FC curves at 40% magma remaining are comparable with measured values of Ne - trachyte compositions. Assimilation of granite by mugearite at low mass assimilation to mass crystallization rates ( r = 0.8) offer a close approximation for Qtz -trachyte and rhyolite (Fig. 30-

32).

In Figure 30, mafic and intermediate rocks have higher K/Rb ratios relative to the potential contaminant. Therefore, the end product of AFC modeling should have a lower K/Rb ratio, which is predicted by the AFC curves. The D values used in these models are from trace element models (ADD -Tables 12) and from Panter et al. (1994). In these models (Fig. 30, 31, 75

n AFC curves position 212.3Pof hand hand markstick o lization D (AFC).values model -trachyte. The field dotted indicates Si- Qtz sition is assimilateTW92-82 with granodioritic com 2-091,TW92-174 are and allization and Assimilation (FC) Crystal Fractional markscurvesare 10%on FC on the otherincrements; Fig. 30. GraphicalFig. presentation FractionalCryst of used for usedthis curves are Tickinthegiven figure. are 2% increments.2% are modelFor parent AFC compomagma (Weaver et (Weaver al., Sample1992). number TW92-006, TW9 oversaturated region. oversaturated region. 76

position212.3Pof turated turated region. ick marks on AFC curves ick on marks AFC are lizationfor used model. D values sitionisassimilateTW92-82 granodioriticcom with as Figure as30. dotted The indicates Si-oversafield allization and Assimilation Crystal (FC) Fractional FC curves 0.10% FC curves are increments;other handon t the Fig. 31. GraphicalFig. presentation FractionalCryst of this marks are Tick in the given figure. oncurves 0.010% increments.0.010% For AFC modelcompo magmaparent (Weaver et (Weaver al., Symbols1992).same are and samples 77

n of 212.3P (Weaver et et 1992). al., n (Weaver 212.3P of ick marks on AFC curves0.025% on marks AFC ick are lization (AFC) model. D values used for used values D model. lization (AFC) is TW92-82 assimilate with granodioritic compositio with granodioritic assimilate is TW92-82 ed field indicates Si-oversaturated region. region. indicates Si-oversaturated field ed allization (FC) and Assimilation Fractional Crystal Fractional andallization Assimilation(FC) FC curves are 0.10% hand other increments; the t curves are FC on Fig. 32. 32. Cryst Graphical presentation Fractional of Fig. marks on Tick figure. the are in this curves given magma Forcomposition AFC parent model increments. Symbols and samples are same as Figure 30. The are The samples Figure as 30. dott same and Symbols 78 and 32) D values for Rb, K, Nb, and Sr are kept constant for both FC and AFC models.

Different D values for Zr and La are used for FC and AFC models in Figures 31 and 32. This is because the D value obtained for La and Zr from the trace element models are quite high with respect to their normal D value. Therefore, those D values are taken from Panter et al. (1994).

Several independent variables control the relative abundance of an element in a magma experiencing AFC and hence its concentration varies. In Figures 31 and 32, the AFC calculations require a high value of r (0.8) and low Nb contents in both the assimilant and the initial magma and low bulk distribution coefficient to best match the trend of Qtz -trachyte to rhyolite.

I conclude that a small amount of granitic assimilant with concurrent fractional crystallization can produce Qtz -trachyte and rhyolite from an intermediate magma composition

(mugearite). The majority of the undersaturated lineage can be explained by 60% crystallization of a basanite to produce Ne -trachyte. It is unlikely that the high-silica Qtz -trachyte and rhyolite can be produced by closed system fractionation crystallization from a silica-undersaturated parent.

CONCLUSIONS

The alkaline rocks of the Crary Mountains show a wide range of compositional variation similar with the alkaline rocks of Mount Sidley (Marie Byrd Land, Antarctica), (Panter et al.,

1997) Cameron Line (Bruke, 2001; Ngounouno et al., 1997) and Kenya rift (Barker et al., 1988).

The rocks show a petrogenetic progression from basanite to phonolite and trachyte. Hawaiite, mugearite, benmorite, tephriphonolite and phonotephrite are identified as intermediate group of rocks at the Crary Mountains. Changes in compositions correlate with stratigraphic height, showing both mafic to felsic and felsic to mafic transitions from bottom to top of the stratigraphic sequences. The overall composition across the range shows a change from a wide compositional spectrum for older rocks at Mts. Steere and Rees to more restricted and mafic compositions for the younger rocks in the rest of the range. This is most likely a consequence of exposure; the older edifies being dissected while only the youngest deposits are exposed at undissected centers (Mt. Frakes and Boyd Ridge, Fig. 1).

Diverse mineral assemblages have been identified for the different rock compositions of the Crary Mountains. The mafic rocks are dominated by the presence of olivine, clinopyroxene and plagioclase feldspar. Olivine phenocrysts are more Mg rich in mafic rocks whereas plagioclase are more Ca-rich. Clinopyroxene phenocrysts are common in all different varieties of rocks. Intermediate rocks are more dominated by clinopyroxene, plagioclase, and alkali feldspar. Apatite and amphibole grains are present in these rocks as accessory phases. The felsic rocks are characterized by the presence of alkali feldspar phenocrysts. Aenigmatite, nepheline, fayalite, and amphibole occur as accessory mineral phases in the felsic rocks.

Geochemical difference between two different types of trachyte and phonolite are established at the Crary Mountains. Using the major and trace element chemistry the different 80 types of trachytes and phonolites are identified. Nephline normative trachytes ( Ne -trachytes) are characterized by high concentration of Ba and Sr with respect to quartz normative trachytes ( Qtz - trachytes). On the other hand the phonolites are differentiated by SiO 2 and K 2O (wt %) concentrations. The low-alkali phonolites have Na 2O + K 2O <13.46 wt% and silica> 60 wt%; where as high-alkali phonolites have Na 2O + K 2O > 15.47 wt% and silica <56 wt%.

Studies of the Crary Mountain alkaline rocks permit the dynamic reconstructions of the petrogenesis history of this region and offer an insight into the genetic relationships between phonolite, trachyte and rhyolite magma series. The geochemical difference between phonolite and trachyte are strongly established by evolution along separate magma trends. Furthermore, each series appears to have originated from a single magma source, but from different parental starting compositions (tephrite → phonolite; basanite → Ne -trachyte; mugearite → Qtz - trachyte). Theoretical modeling of geochemical variations reveals that crystal-liquid fractionation processes were dominant during phonolite production; AFC played an important role in Qtz -trachyte and rhyolite genesis and lead to production of silica-oversaturated compositions.

The compositional change from mafic to felsic magma in the Crary Mountains can be related to different magma differentiation processes. My models show that fractional crystallization of basanite can produce Ne -trachyte (16%). Hawaiite, mugearite, and benmoreite all of the intermediate rocks are also produced by fractional crystallization of basanite magma.

The major element least square models that I produce to show the fractional crystallization model for these rocks are well supported by the trace element modeling.

The production of undersaturated phonolitic rocks is also described by fractional crystallization. Fractionation of tephritic magma can lead to production of phonolitic rocks. The 81 trace element model fit with the major element mass balance equation properly.. The other model of fractionation from benmoreite to phonolite work properly for major element mass balance equation but, didn’t work properly for trace element chemistry; however, it shows some close resemblance with the chemical composition

The silica saturated rocks of the Crary Mountains are produced by assimilation of continental crust. The fractional crystallization model that I produced to determine the production of Qtz -trachyte from Ne -trachyte do not fit properly with least square mass balance equation, not even with the trace element model. However, as I contaminate the mugearitc magma with granitic country rocks it produces magma similar in composition with the Qtz - trachyte and rhyolite rocks of the Crary Mountains.

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-APPENDIX-

APPENDIX 1.- Petrography of the Crary Mountains alkaline rock samples.

100

101

102

103

104

105

106

107

108

109

73.84 Tephrite

169 169 74.36 Tephrite

0.22 0.25 0.29 0.26 0 9 1 1.00 9 0.50 1 0.01 1.00 1.48 0.52 0.01 0.01 1.47 0.01 Steere Mt. Steere Steere Mt. 3.00 3.00 3.00 74.95 Tephrite es are the same the are es inas 1. Table

m Mount and Rees MountCrary Steere, .11 38.32 38.39 38.29 4.46 22.45 23.04 23.65 72.45 36.58 38.13 37.97 37.87

.69 99.87 99.56 100.03 100.44 75.13

77.09

00. r= c= rim, core. typabbreviations The for rock 76.98 livine phenocrysts phenocrysts cores-rimslivineanalyzedlavas in fro the prefixthe ‘TW92-’.

60.65

Phnt Phnt Phnt Phnt Phnt Tephrite Tephrite Boyd Boyd Boyd Boyd Boyd Boyd Mt.Steere Mt. Steere Mt. 64.00

40.33 Morison Phonolite

45.69

34.52 33.71 36.74 36.32 38.68 38.88 38.99 38.24 38 2

Si 1.01 1.01 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.0 Fe 1.03 1.12 0.70 0.76 0.45 0.45 0.49 0.49 0.54 0.4 Ca 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.0 Mn Mg 0.04 0.90 0.05 0.79 0.01 1.27 0.02 1.20 0.01 1.53 0.01 1.54 0.01 1.53 0.01 1.50 0.01 1.44 0.0 1.4 FeO 42.3 44.85 30.77 33.2 20.95 20.99 20.84 22.36 2 CaO 0.43 0.42 0.38 0.41 0.2 0.21 0.18 0.2 0.25 0.24 Fo% SiO MnO MgO 1.52 20.7 2.11 17.82 0.62 31.32 29.38 0.76 39.87 0.29 40.14 0.26 39.93 0.3 38.43 0.3 0.32 0.26 Total 2.99 2.99 3.00 3.00 3.00 3.01 3.00 3.00 3.00 Total 99.6 98.99 100 100.27 100.19 100.68 100.44 99 Position rs rs rs cs r c r c r c r c Location Morison RockType Phonolite SampleNo. 121 121 139 139 139 139 139 169 169 169 APPENDIX-2.1. RepresentativeAPPENDIX-2.1. chemical analysis o of Mountains, Antarctica. AllMountains,No.’s Antarctica. withsample begin Cationson 4based Mg# =oxygens, (MgO/MgO+FeO)*1 Wt% oxide

110

29.38 Mt. Rees Benmorite

2.08 2 0.54 9 7 5 0.99 7 1.36 2 0.05 0.59 0.02 3.01 3.01 28.61 Mt. Rees Benmorite

.44 32.22 32.41 29.27 Mt. Rees Benmorite

52.59 12.69 53.24 12.44 52.86 12.83

28.27 es are the same as in Table 1. Table in as same the esare Mt. Rees Benmorite

18 100.15 100.28 100.48 100.7 00 57. Mt. Rees Benmorite

59.14

59.52 Mt. Rees Mt. Rees

Boyd 77.29 00. r= rim, c= core. The abbreviations for rock typ rock for abbreviations The c= core. r=rim, 00.

77.46

Phnt Phnt Phnt Phnt Benmorite Benmorite 77.08

73.10

38.42 38.83 38.80 38.92 36.23 36.21 35.66 32.44 32 2

Si 1.00 1.00 1.00 1.00 0.99 1.00 1.00 1.00 1.00 0.9 Fe 0.53 0.45 0.45 0.45 0.80 0.80 0.84 1.37 1.35 1.3 Ca Ca 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.02 0.02 0.0 Mn Mg 0.01 1.45 0.01 1.54 0.00 1.55 0.01 1.54 0.02 1.20 0.02 1.18 0.02 1.14 0.05 0.56 0.05 0.58 0.0 0.5 FeO FeO 24.15 21.10 20.85 20.85 34.81 34.68 35.95 52.93 CaO CaO 0.23 0.22 0.19 0.2 0.34 0.32 0.35 0.54 0.53 0.5 SiO Fo% MnO 0.32 0.29 0.19 0.24 0.8 0.8 0.84 2.06 2.02 2.05 MgO 37.33 40.38 40.59 40.19 29.39 28.83 27.37 12.17 Total 100.65 100.82 100.62 100.4 101.57 100.84 100. Total 3.00 3.00 3.01 3.00 3.01 3.00 3.01 3.00 3.00 Position r r c r r c r r r c c Location Location Mt. Steere Boyd Boyd Rock Type Rock Tephrite Sample No. Sample 169 139 139 139 23 23 23 23 23 23 23 Wt% oxide

(MgO/MgO+FeO)*1 = Mg# oxygens, 4 on based Cations 111 te es are the same as in Table 1. Table in as same the esare es 00. r= rim, c= core. The abbreviations for rock typ rock for abbreviations The c= core. r=rim, 00. Trachyte Trachyte Trachyte Trachyte Trachyte Trachyte Trachy Mt. Rees Mt. Rees Mt. Rees Mt. Rees Mt. Rees Mt. Re 29.54 29.72 29.75 29.52 29.91 29.34 2

Si 1.02 1.02 1.02 1.01 1.05 1.01 Fe Fe 1.87 1.87 1.87 1.83 1.74 1.83 Ca Ca 0.00 0.01 0.01 0.04 0.04 0.04 Mn Mg 0.09 0.00 0.08 0.00 0.08 0.00 0.09 0.03 0.11 0.02 0.09 0.03 FeO FeO 65.03 65.27 65.17 63.87 59.21 63.68 CaO CaO 0.21 0.22 0.25 1 0.95 1.12 SiO Fo% Fo% 0.00 0.03 0.00 1.41 1.26 1.34 Total 2.98 2.98 2.98 2.99 2.95 2.99 MnO MgO Total 2.97 0 97.92 2.73 0.01 98.09 2.88 98.2 0 3.17 98.24 0.54 3.55 94.7 0.45 3.17 98.54 0.51 Position c c c c c r Location Location Wt% oxide Rocky Rocky type Sample No.Sample 15 15 15 174 174 174

(MgO/MgO+FeO)*1 = Mg# oxygens, 4 on based Cations 112

9 .49 0.85 Trachyte

1 1 1 1.99 5 0.02 4 0.02 0 1.00 4 0.04 7 0.01 0.88 0.07

08 0.37 06 03 1.05 0.18 4.20 4.02 Trachyte

Table1. 49.24 47.95 0.42 3 19.67 99.42 96.9 99.36 Trachyte Mt. Rees Mt. Rees Mt. Rees Mt. Rees ysts analyzed in lavas from the the in from lavas analyzed ysts

1.76 7.94 40.46 97.32 91.98 59.16 23.27 34.77 28.76 Phonolite Morrison

Phonolite Morrison

The abbreviations for rock types are the same as in as the same are rock types for abbreviations The Phonolite Morrison

Phonolite linopyroxene phenocrysts core-rims and microphenocr and core-rims phenocrysts linopyroxene Morrison Wollastonite. Wollastonite. -

h the prefix ‘TW92-’. ‘TW92-’. prefix the h lite , mp= mcrophenocryst. ,mcrophenocryst. mp= Wo Phono Morrison

Ferrosillite. Ferrosillite. - Phonolite Morrison

Phonolite Fs Enstatite, -

1.27 1.4 0.6 1.11 1.78 1.34 0.85 1.04 0.7 0.12 0.3 0.62 0.48 0.34 0.83 1.05 0.7 0.43 0.58 2.16 0.37 0 49.23 49.17 49.4 49.28 48.62 49.4 49.02 50.4 60.44 3 2 2 O 2.87 4.2 2.53 3.54 3.21 3.33 1.19 2.82 10.73 6.9 O 2

2 Si Si 1.99 1.99 2.00 1.99 1.98 1.99 2.01 2.01 2.31 2.1 Ti 0.02 0.02 0.01 0.03 0.03 0.02 0.01 0.02 0.06 0.0 Al Al Fe 0.06 0.76 0.07 0.77 0.03 0.80 0.05 0.73 0.09 0.80 0.06 0.77 0.04 0.80 0.05 0.71 0.03 0.74 0.0 1.2 Ca Ca 0.79 0.75 0.82 0.75 0.76 0.76 0.83 0.77 0.02 0.1 Na Na 0.23 0.33 0.20 0.28 0.25 0.26 0.09 0.22 0.79 0.5 Mn Mn Mg 0.03 0.20 0.04 0.17 0.04 0.18 0.04 0.24 0.04 0.14 0.04 0.19 0.05 0.16 0.04 0.25 0.05 0.01 0.0 0.0 FeO 22.59 22.72 23.65 21.72 23.48 22.69 23.21 21.28 Fs% Fs% 51.25 52.96 52.20 50.44 54.49 52.38 51.99 49.10 CaO CaO 18.22 17.36 18.77 17.39 17.38 17.54 18.82 17.9 SiO En% En% 7.42 6.57 6.38 9.17 5.18 7.13 5.85 9.60 0.92 0. TiO MnO MnO MgO 0.99 3.27 1.05 2.82 1.09 2.89 1.17 3.95 1.17 2.23 1.25 3.09 1.49 2.61 1.19 4.16 1.42 0.22 1. 0. Total 99.07 99.22 99.28 99 98.93 99.37 97.62 99.39 Total 4.08 4.13 4.07 4.10 4.08 4.09 4.00 4.06 4.02 Na Wo% 41.33 40.47 41.43 40.39 40.33 40.49 42.16 41.30 Al Position cs cs cs cs rs rs cs cs r c c Location Location Morrison Rock Rock Type Wt% Wt% oxide Sample No. 134 134 134 134 134 134 134 134 15 15 15 Abbreviation. En Abbreviation.

Crary Mountains. All sample No.’s being wit No.’s being All sample Mountains. Crary APPENDIX-2.2 Representative chemical analysis of c of analysis chemical Representative APPENDIX-2.2 core rim, c= r= 6oxygens,. on based Cations 113 45 .77 .89 6.42 5.13 20.84 4 99.44

the same as in Table 1. 1. Table in as same the on Morrison Morrison Morrison Morrison nolite nolite Phonolite Phonolite Phonolite Phonolite

crophenocryst. crophenocryst. Wollastonite. The abbreviations for rock types are are types rock for abbreviations The Wollastonite. 0.4 0.38 1.39 1.76 1.34 1.16 1.16 1.15 1.2 0.42 0.39 0.58 0.53 0.48 0.43 0.44 0.44 0.5 48.33 46.44 51.75 52.35 50.57 50.94 50.88 50.37 50 3 2 2 O 0.78 0.8 -0.15 0.64 1 0.86 -0.47 0.94 1.11 O 2

2 Si Si 2.00 2.00 1.98 1.96 1.97 1.98 1.99 1.98 1.98 Ti 0.01 0.01 0.02 0.02 0.01 0.01 0.01 0.01 0.02 Al Al Fe 0.02 1.00 0.02 1.00 0.06 0.41 0.08 0.30 0.06 0.52 0.05 0.49 0.05 0.52 0.05 0.53 0.06 0.51 Ca Ca 0.86 0.87 0.86 0.85 0.89 0.90 0.90 0.89 0.87 Na Na 0.06 0.07 0.00 0.05 0.08 0.07 0.00 0.07 0.08 Mn Mn Mg 0.04 0.01 0.03 0.01 0.02 0.62 0.01 0.75 0.03 0.47 0.02 0.49 0.03 0.46 0.02 0.45 0.03 0.48 FeO FeO 28.76 27.88 12.81 9.5 15.85 15.2 15.96 16.25 15 Fs% Fs% 59.45 59.36 28.69 14.2 25.4 33.52 35.25 36.01 3 CaO CaO 19.43 18.91 20.96 21.28 21.19 21.61 21.46 21.17 SiO En% En% 0.39 0.38 24.37 40.1 25.7 18.83 17.36 17.08 18. TiO MnO MnO MgO 1.01 0.19 0.93 0.18 0.6 10.88 13.45 0.39 7.99 0.78 8.54 0.73 7.86 0.75 7.71 0.72 8.28 0.8 Total 99.35 95.96 98.98 99.91 99.23 99.5 98.51 98.7 Total 4.01 4.02 3.97 4.01 4.02 4.02 3.97 4.02 4.02 Na Wo% 40.16 40.26 46.94 45.7 48.9 47.65 47.39 46.91 4 Al Position Position r r c c r c r r r Location Location Rees Mt. Rees Mt. Morrison Morrison Morris Rock Type Rock Trachyte Trachyte Phonolite Phonolite Pho Wt% oxide Wt% Sample No. Sample 15 15 121 121 121 121 121 121 121 Cations based on 6 oxygens,. r= rim, c= core, mp= m mp= core, c= rim, r= oxygens,. 6 on based Cations Wo- Ferrosillite. Fs- Enstatite, En- Abbreviation.

114 te te 7 40.84 57.09

5 19.75 9 99.17 9 47.95 8 27.61

Table 1. Table

on on Mt.Rees Mt.Rees Mt. Rees Mt. Rees Mt. Rees honolite honolite Trachyte Trachyte Trachyte Trachyte Trachy The abbreviations for rock types are the same in as same the are types forrock The abbreviations crophenocryst. crophenocryst. Wollastonite. Wollastonite. - Wo Ferrosillite. -

0.4 0.36 0.86 0.03 0.45 0.63 0.61 0.8 0.53 0.58 1.99 0.01 0.05 1.99 0.53 0.01 0.03 0.06 0.46 1.95 0.50 0.89 0.03 0.02 0.07 0.09 0.49 4.02 1.51 0.38 0.87 0.00 0.02 0.09 0.00 0.66 4.02 1.98 2.13 0.84 0.01 0.13 0.05 0.06 0.68 4.01 1.98 0.53 0.04 0.02 0.03 0.01 0.03 0.45 4.49 1.98 0.97 0.87 0.02 0.03 0.08 0.03 0.05 4.02 1.97 0.97 0.89 0.03 0.04 0.04 0.04 0.05 4.01 0.99 1.99 0.88 0.04 0.02 0.04 0.03 0.03 4.00 0.87 0.96 1.98 0.05 0.04 0.02 4.01 0.05 0.03 0.88 0.96 0.04 0.04 4.00 0.06 0.88 0.05 4.01 1.01 1.21 2.08 0 1.31 0.66 0.68 0.76 0.51 0.67 0.76 7.94 0.72 8.32 0.54 11.53 3.22 9.49 0.76 7.71 0.96 0.73 0.99 0.76 1.05 0.53 1.03 0.76 1.04 1 0.94 1.18 0.67 0.06 1.11 0.5 0.5 0.63 0.51 0.56 46.99 46.59 46.75 1.15 46.47 41.13 46.7 46.6 41.13 17.52 18.72 26.18 14.93 17.16 1.51 2.5 1.8 1.57 2.0 35.49 34.69 27.07 83.93 36.37 57.36 50.8 51.6 57.31 16.08 15.42 11.92 53.36 16.34 27.81 27.86 28.47 27. 21.29 20.71 20.59 0.73 20.88 19.94 19.83 19.39 19.9 99.29 98.73 99.3 98.53 99.49 98.92 99.03 98.99 99.1 50.88 50.78 51.1 31.65 50.94 47.66 47.81 47.33 48.0 Enstatite, Fs Enstatite, -

3 2 2 O O O 2

2 Si Si Ti Al Al Fe Ca Ca Na Mn Mn Mg FeO FeO Fs% Fs% CaO CaO SiO En% TiO Total MnO MnO MgO Total Na Wo% Al Position Position c r c c r r r c rs c Location Morrison Morrison Morrison Morrison Morris Rock Rock Type Phonolite Phonolite Phonolite Phonolite P Wt%oxide Sample No. Sample 121 121 121 121 121 174 174 174 174 174 Cations based on 6 oxygens,. r= rim, c= core, mp= m core, mp= c= rim, r= 6 oxygens,. on based Cations Abbreviation. En Abbreviation. 115 25 7.18 .15 4.52 waiite waiite Hawaiite Rees Rees Mt. Rees 0.65 0.42 3 8 8 1.74 0 0.12 1 0.28 6 1.70 0.33 0 0.13 0.01 3 0.33 0.61 0.34 0.89 0.01 0.05 0.58 0.90 0.03 28 0.21 0.19 014 014 014 4.01 4.03 4.02

e 1. e 82 22.36 24.95 23.87 23 47.6 45.56 44.05 0.07 9.83 10.72 10.12 5.40 28.05 24.11 25.08 0.78 49.59 50.94 51.05 21.47 21.8 21.89 21.64 10.74 12.33 10.36 10.63 Tabl 7 98.93 99.25 99.81 98.77

ite ite Hawaiite Hawaiite Hawaiite Hawaiite Hawaiite Ha es Mt. Rees Rees Mt. Rees Mt. Mt. Rees Rees Mt. Mt. The abbreviations for rock types are the same asin same the types are rock for abbreviations The crophenocryst. crophenocryst. Wollastonite. Wollastonite. - Wo Ferrosillite. Ferrosillite. -

Enstatite, Fs Enstatite, - 0.8 0.75 5.15 5.46 4.7 6.38 4.71 6.06 6.93 4.04 6. 0.68 0.64 3.5 2.87 3.08 4.73 2.95 4.32 4.55 2.89 4 47.74 47.68 46.82 46.1 47.24 44.65 47.42 45.38 44. 3 2 2 O 0.54 0.55 0.62 0.66 0.65 0.69 0.63 0.67 0.69 0.44 O 2

2 Si 1.98 1.98 1.79 1.78 1.80 1.72 1.81 1.73 1.71 1.8 Ti 0.02 0.02 0.10 0.08 0.09 0.14 0.09 0.12 0.13 0.0 Al Al Fe 0.04 0.98 0.04 0.98 0.23 0.36 0.25 0.41 0.21 0.35 0.29 0.34 0.21 0.34 0.27 0.34 0.32 0.35 0.1 0.4 Ca Ca 0.85 0.88 0.89 0.83 0.91 0.90 0.90 0.92 0.89 0.9 Na Na 0.04 0.04 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.0 Mn Mg 0.04 0.04 0.04 0.04 0.01 0.60 0.01 0.63 0.01 0.61 0.01 0.58 0.01 0.62 0.01 0.59 0.01 0.58 0.0 0.5 FeO 28.18 28.24 11.3 12.58 10.84 10.54 10.68 10.64 Fs% Fs% 58.68 58.21 25.93 28.88 24.77 15.5 15.3 24.54 2 CaO CaO 19.17 19.7 21.79 20.01 22.16 21.93 22.07 22.38 SiO En% En% 1.40 1.18 24.07 25.18 24.61 33.1 34.4 23.85 23. TiO MnO 1.14 1.04 0.24 0.21 0.27 0.17 0.21 0.18 0.18 0. MgO 0.67 0.57 10.49 10.97 10.77 10.13 10.86 10.34 1 Total 4.00 4.01 4.02 4.05 4.03 4.03 4.02 4.03 4.03 Total 98.95 99.16 99.91 99.4 99.72 99.23 99.55 99.9 Na Wo% 39.92 40.61 50.00 45.94 50.63 51.5 50.3 51.61 5 Al Position Position r r cs cs cs cs cs cs cs cs cs cs Location Location Mt. Rees Rees Mt. Mt. Rees Rees Mt. Re Mt. Rock Type Type Rock Trachyte Trachyte Hawaiite Hawaiite Hawai Wt% oxideWt% Sample No. Sample 174 174 014 014 014 014 014 014 014 m core,mp= c= rim, r= 6 oxygens,. on based Cations Abbreviation. En Abbreviation.

116

Rees Mt. Rees .61 2.74 0.47 0.12 1.09 1.17 023 023 e Benmorite Benmorite 0.46 0.49 4 2 8 1.92 1 0.03 2 0.12 2 1.92 0.42 0 0.03 0.02 3 0.13 0.59 0.44 0.89 0.02 0.04 0.57 0.87 0.01

4.01 4.01 3.99 9 10.74 10.25 9.77 38 50.51 49.84 49.31 21.26 21.86 21.6 20.94 10.43 12.83 12.95 13.56 49.46 26.27 24.27 47.7 32.6 19.7 47.8 31.5 20.7 47.30 22.07 30.63 9 98.45 99.19 99.29 98.15 the same as in Table 1. Table as in same the es Mt. Rees Rees Mt. Mt. Rees Mt. Rees Rees Mt. Mt. ite ite Hawaiite Benmorite Benmorite Benmorite Benmorit crophenocryst. crophenocryst. Wollastonite. The abbreviations for rock types are are types rock for abbreviations The Wollastonite.

5.21 7.34 3.9 6.89 3.66 4.46 1.70 1.71 5.00 1.70 2 3.52 4.96 2.91 4.64 2.46 2.70 0.86 0.78 2.24 0.70 46.51 43.86 47.9 44.45 48.13 47.41 50.61 50.81 47. 3 2 2 O 0.63 0.46 0.68 0.72 0.76 0.65 0.43 0.38 0.57 0.4 O 2

2 Si 1.78 1.69 1.84 1.71 1.85 1.82 1.94 1.95 1.82 1.9 Ti 0.10 0.14 0.08 0.13 0.07 0.08 0.03 0.02 0.07 0.0 Al Al Fe 0.24 0.35 0.33 0.35 0.18 0.41 0.31 0.35 0.17 0.41 0.20 0.37 0.08 0.38 0.08 0.38 0.23 0.34 0.0 0.4 Ca Ca 0.89 0.90 0.89 0.89 0.88 0.90 0.88 0.88 0.88 0.9 Na Na 0.05 0.04 0.05 0.05 0.06 0.05 0.03 0.03 0.04 0.0 Mn Mg 0.01 0.61 0.01 0.56 0.01 0.56 0.01 0.56 0.01 0.57 0.01 0.60 0.01 0.66 0.01 0.66 0.01 0.65 0.0 0.6 FeO 10.94 10.75 12.62 11.01 12.75 11.43 11.78 11.79 Fs% Fs% 25.32 25.32 28.66 25.92 28.96 26.12 26.34 26.39 CaO CaO 21.64 21.88 21.58 21.66 21.35 21.77 21.48 21.35 SiO En% En% 24.60 23.15 22.33 23.08 22.54 24.13 25.64 25.81 TiO Total 99.33 99.29 99.68 99.4 99.31 99.29 98.78 98.7 Total 4.02 4.02 4.01 4.03 4.02 4.03 4.01 4.01 4.02 MnO 0.23 0.2 0.25 0.22 0.29 0.3 0.41 0.42 0.28 0.45 MgO 10.63 9.83 9.83 9.8 9.92 10.56 11.47 11.53 11.2 Na Wo% 50.08 51.53 49.01 51.00 48.50 49.75 48.02 47.79 Al Position Position cs cs cs cs cs cs c c r c r r Location Location Rees Mt. Rees Mt. Mt. Rees Rees Mt. Mt. Re Rock Type Type Rock Hawaiite Hawaiite Hawaiite Hawaiite Hawai Wt% oxideWt% Sample No. Sample 014 014 014 014 014 014 023 023 023 023

Cations based on 6 oxygens,. r= rim, c= core, mp= m mp= core, c= rim, r= oxygens,. 6 on based Cations Wo- Ferrosillite. Fs- Enstatite, En- Abbreviation. 117

79 79 179 179 phn phn Tphn Tphn 0.46 0.65 0.51 1.68 2.02 1.82

. 0.63 0.69 0.67 4 4 2 8 1.94 3 0.01 2 0.08 1.94 2 0.46 0.02 7 0.02 0.09 1.94 5 0.60 0.43 0.02 0.88 0.02 0.08 0.05 0.62 0.45 0.86 0.02 0.05 0.59 0.88 0.05 57 57 0.61 0.53 0.58 4.03 4.03 4.02 4.03 Table 1 Table yd yd Boyd Boyd Boyd Boyd .77 51.01 50.81 50.46 50.66 47.23 22.07 46.67 31.34 24.10 46.68 29.72 22.69 46.03 31.08 23.69 46.59 29.78 22.62 30.79 10.14 21.70 10.98 21.26 10.44 21.48 10.74 20.87 10.35 21.32 14.40 13.54 14.30 13.50 14.09 .22 .22 100.84 100.65 100.49 100.44 99.50 99.99 The abbreviations for rock types are the same as in same the types are rock for abbreviations The crophenocryst. crophenocryst. Wollastonite. Wollastonite. - Wo Ferrosillite. Ferrosillite. - Enstatite, Fs Enstatite, - Tphn Tphn Tphn Tphn Tphn Tphn Tphn Tphn Tphn Tphn T En 1.73 2.10 1.98 1.86 1.77 1.85 2.14 2.00 1.72 1.80 0.77 0.60 0.55 0.57 0.55 0.57 0.59 0.64 0.56 0.60 50.96 50.61 50.76 50.83 50.97 50.68 50.40 50.83 50 3 2 2 O 0.60 0.73 0.79 0.76 0.81 0.77 0.71 0.70 0.70 0.74 O 2

2 Si Si 1.93 1.94 1.94 1.93 1.94 1.94 1.93 1.93 1.94 1.9 Ti 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.0 Al Al 0.08 0.10 0.09 0.08 0.08 0.08 0.10 0.09 0.08 0.0 Fe Fe 0.40 0.44 0.44 0.45 0.46 0.44 0.46 0.44 0.46 0.4 Ca 0.87 0.88 0.88 0.89 0.87 0.88 0.87 0.88 0.89 0.8 Na Na 0.04 0.05 0.06 0.06 0.06 0.06 0.05 0.05 0.05 0.0 Mn Mn Mg 0.02 0.66 0.02 0.59 0.02 0.60 0.02 0.59 0.02 0.59 0.02 0.60 0.02 0.58 0.02 0.61 0.02 0.58 0.0 0.6 FeO FeO 12.73 13.80 13.89 14.10 14.28 13.79 14.31 13.81 Fs% Fs% 27.94 30.40 30.44 30.73 31.31 30.24 31.36 30.20 CaO 21.38 21.41 21.49 21.87 21.26 21.42 21.21 21.59 SiO En% En% 25.50 22.67 22.99 22.62 22.71 22.94 22.38 23.42 TiO Total 4.03 4.03 4.03 4.04 4.03 4.03 4.03 4.03 4.03 Total 100.37 100.22 100.54 101.02 100.63 100.16 100 MgO 11.62 10.29 10.49 10.38 10.36 10.46 10.21 10.71 MnO 0.58 0.68 0.58 0.66 0.64 0.61 0.63 0.54 0.64 0. Na Wo% 46.93 47.16 47.10 47.67 46.61 46.98 46.48 47.22 Al Position c r c r c r c c c r c r r Location Location Boyd Boyd Boyd Boyd Boyd Boyd Boyd Boyd Bo Sample No Sample 179 179 179 179 179 179 179 179 179 179 1 Rocky Tpye Rocky Abbreviation. oxide Wt% m mp= c= core, r=rim, oxygens,. 6 on based Cations

118 0.95 2.34 1.79 1 4 1 1.51 3 0.04 2 0.16 8 1.76 1 0.13 3 0.27 0.40 0.20 54 2.58 4.02 4.47 ugearite ugearite Mugearite

yd yd Boyd Boyd .06 49.97 25.76 10.38 11.88 3.03 Table 1 Table 46.48 23.44 29.95 43.75 26.31 29.79 10.98 5.27 62.40 13.26 13.45 35.86 20.58 19.75 6.31 .07 99.87 99.85 78.65 Mugearite Mugearite Mugearite Mugearite Mugearite Mugearite M The abbreviations for rock types are the same in as same the are types forrock The abbreviations crophenocryst. crophenocryst. Wollastonite. Wollastonite. - Wo Ferrosillite. - Enstatite, Fs Enstatite, - 2.70 3.45 1.41 4.56 4.27 5.48 2.41 3.55 4.67 2.40 1.77 1.81 1.32 2.56 2.02 2.81 1.40 1.98 2.83 1.42 49.32 49.57 50.10 47.11 48.02 46.62 49.99 48.72 47 3 2 2 O O 0.67 0.90 0.59 0.62 0.61 0.69 0.67 0.17 0.61 0.42 O 2

2 Si Si 1.89 1.90 1.94 1.82 1.84 1.78 1.91 1.87 1.81 1.9 Ti 0.05 0.05 0.04 0.07 0.06 0.08 0.04 0.06 0.08 0.0 Al Al 0.12 0.16 0.06 0.21 0.19 0.25 0.11 0.16 0.21 0.1 Fe Fe 0.41 0.44 0.49 0.42 0.41 0.42 0.42 0.41 0.43 0.4 Ca Ca 0.84 0.81 0.83 0.85 0.84 0.84 0.85 0.83 0.85 0.8 Na 0.05 0.07 0.04 0.05 0.05 0.05 0.05 0.01 0.05 0.0 Mn Mn Mg 0.02 0.66 0.02 0.57 0.02 0.58 0.01 0.60 0.01 0.62 0.01 0.61 0.02 0.64 0.01 0.64 0.02 0.59 0.0 0.6 FeO FeO 12.74 13.84 15.22 13.13 12.84 13.06 13.02 12.87 Fs% Fs% 28.40 31.72 33.43 29.57 28.98 29.63 28.95 28.85 CaO CaO 20.44 19.72 20.04 20.60 20.33 20.50 20.74 20.07 SiO En% 25.70 22.92 21.94 23.49 24.51 24.07 24.86 25.24 TiO Total 4.03 4.01 4.01 4.03 4.02 4.04 4.02 4.00 4.03 Total 99.66 99.85 99.39 99.45 99.36 100.21 99.93 99 MnO MnO 0.47 0.56 0.69 0.43 0.41 0.44 0.51 0.43 0.47 0. MgO MgO 11.53 10.00 9.99 10.43 10.86 10.61 11.18 11.26 Na Wo% 45.56 45.20 44.02 46.39 45.88 46.51 46.12 44.98 Al Position Position c c r r c cs cr cr cs cs cs Location Boyd Boyd Boyd Boyd Boyd Boyd Boyd Boyd Bo Sample No Sample 41 41 41 41 41 41 41 41 41 41 41 Wt%oxide Rocky TpyeRocky Mugearite Mugearite Mugearite Mugearite

Cations based on 6 oxygens,. r= rim, c= core, mp= m core, mp= c= rim, r= 6 oxygens,. on based Cations En Abbreviation. 119

Table 1. Table The abbreviations for rock types are the same in as same the are types forrock The abbreviations crophenocryst. crophenocryst. Wollastonite. Wollastonite. - Wo . Ferrosillite - Enstatite, Fs Enstatite, - 3.03 3.97 0.94 1.21 47.07 51.14 3 2 2 O O 1.69 1.24 O 2

2 Si 1.89 1.93 Ti 0.03 0.03 Al Al 0.14 0.18 Fe Fe 0.41 0.38 Ca Ca 0.82 0.78 Na 0.13 0.09 Mn Mn Mg 0.02 0.64 0.02 0.60 FeO 12.34 11.93 Fs% Fs% 27.92 28.49 CaO CaO 19.07 19.28 SiO TiO En% En% 24.36 25.29 MnO MnO MgO 0.51 10.77 0.46 10.59 Total 4.08 3.99 Total 95.42 99.83 Na Wo% 43.14 46.05 Al Position cr cr Location Location Boyd Boyd Sample No Sample 41.00 41.00 Wt% Wt% oxide Rocky TpyeRocky Mugearite Mugearite

Cations based on 6 oxygens,. r= rim, c= core, mp= m core, mp= c= rim, r= 6 oxygens,. on based Cations En Abbreviation. 120

lbite, and lbite, and

03 Pl Hawaiite Mt.Rees

cs cs cs Pl 014 014 Hawaiite Mt. Mt. Rees

4.03 4.36 0.19 0.21 0.01 0.01

2 8 2.35 1.66 2.37 1.62 4 3 0.61 0.35 0.60 0.38 71 0.71 0.77 14 01 0.20 0.03 0.21 0.04 .10 1.12 1.25 cs Pl Hawaiite Mt.Rees

analyzed in lavas from the Crary Crary the in lavas from analyzed 5.01 5.01 5.02

24 11.22 12.67 12.25 .92 53.73 51.91 52.14 .09 29.86 31.10 30.27 cs Pl eviations for rock types and minerals are the minerals and typesrock eviations for Hawaiite Mt. Mt. Rees

75.14 23.76 68.67 30.23 75.01 23.86 72.83 25.92

cs Pl Hawaiite Mt.Rees

7 100.65 99.04 100.77 100.83 100.26

O within minerals. Abbreviation- An-Anorthite, Ab-A An-Anorthite, Abbreviation- withinO minerals. cs Pl 2 Hawaiite Mt. Mt. Rees

of Na of

cs Pl Hawaiite Mt.Rees

cs Pl Hawaiite Mt. Mt. Rees eldspar phenocrysts core-rims and microphenocrysts microphenocrysts and core-rims phenocrysts eldspar

Pl crophenocrysts. “-” below detection limit. abbr The detection “-” below crophenocrysts. Mt. TW92-’. TW92-’. Steere Steere Tephrite

Pl Mt. Mt. Steere Tephrite

Pl Mt. Steere Steere Tephrite

High values of oxides are due to high concentration to high are due valuesoxides of High

Mt. Mt. Steere Note- Tephrite 23.35 23.29 22.72 29.22 31.01 30.19 22.11 31.19 30 63.18 63.25 64.26 53.65 51.90 53.06 64.31 51.54 50 3 2 O O 8.19 9.22 9.48 4.84 3.97 4.54 8.56 3.96 3.87 4.94 O O 0.63 0.54 0.48 0.33 0.19 0.19 2.55 0.17 0.18 0.18 O 2

2 2 K K 0.04 0.03 0.03 0.02 0.01 0.01 0.14 0.01 0.01 0.01 Si 2.81 2.80 2.83 2.43 2.35 2.40 2.84 2.33 2.35 2.4 Sr Sr - - - 0.01 0.01 0.01 0.01 0.01 0.01 - 0.01 0.01 Al Al Fe 1.22 - 1.21 1.18 - 1.56 - 1.65 0.03 1.61 0.03 1.15 0.03 1.66 0.03 1.64 0.03 1.5 0.06 0.03 0.03 0. Ba ------Ca Ca 0.18 0.17 0.14 0.53 0.61 0.56 0.11 0.63 0.61 0.5 Na 0.71 0.79 0.81 0.43 0.35 0.40 0.73 0.35 0.35 0.4 SrO SrO 0.15 0.16 0.16 0.33 0.25 0.19 0.19 0.21 0.23 0. FeO 0.06 0.03 0.01 0.72 0.89 0.75 0.75 0.67 1.50 0. K CaO CaO 3.79 3.63 3.05 10.89 12.68 11.64 2.40 12.91 12. BaO 0.03 0.05 0.10 0.01 0.01 0.01 0.19 0.01 0.02 0. SiO Or% 5.00 4.03 3.69 2.05 1.13 1.16 18.87 1.00 1.10 1 An% An% Ab% 30.06 64.95 27.11 68.86 23.44 72.87 67.81 30.14 75.30 23.57 71.11 27.73 17.76 63.36 75.76 23.24 Total 99.40 100.16 100.25 99.99 100.91 100.57 101.0 Na Al Total 4.96 5.01 5.00 5.01 5.01 5.01 5.02 5.01 5.01 Mineral Pl Position r c r cs Location Location Rock Type Type Rock Wt% Wt% oxide Sample No. Sample 169 169 169 169 014 014 014 014 014 014 Mountains. All sample No.’s being with the prefix ‘ prefix the with being No.’s All sample Mountains. APPENDIX-2.3- Representative chemical analysis f chemical of Representative APPENDIX-2.3- Cations based on 8 oxygens. r= rim, c= core, c= mp= mi rim, r= 8 oxygens. on based Cations Or-Ortoclase. Or-Ortoclase. same as in Table 1. 1. in Table as same 121 as in as

.02 Pl 0.12 Ortoclase. Ortoclase. - 0.05 0.93

7 6 0.31 0.63 8 2 2.64 1.36 39 0.53 65 7.29 .12 0.18 Pl 5.62 6.39 Albite, and Or Albite, and - 5.02 5.02

82 7.85 6.37 .52 60.61 59.25 .57 25.36 25.85 Pl 47.08 53.13 49.90 Anorthite, Ab Anorthite, -

Af 1.58 48.10 39.03 43.74 An - eviations for rock types and minerals are the same same the are minerals and types forrock eviations

45 84.94 100.86 101.04 100.52 Af Abbreviation

Pl Boyd Boyd Boyd Boyd Boyd Boyd Boyd

Mugearite Mugearite Mugearite Mugearite Mugearite Tphn Tphn

O within minerals. minerals. within O 2 Pl Phnt of Na

Pl Phnt crophenocrysts. “-” below detection limit. Theabbr limit. detection below “-” crophenocrysts.

Af Phnt

Af Boyd Boyd Boyd Boyd Boyd High values of oxides are due to high concentration to high due are of oxides values High 20.77 20.28 19.75 28.87 29.31 26.43 21.94 21.48 26 67.29 66.35 64.99 54.69 54.26 58.01 50.04 49.67 58 3 2 O O 9.06 8.93 7.91 5.27 5.05 6.86 11.20 10.05 6.94 7. O O 3.64 3.98 6.49 0.38 0.36 0.72 2.63 3.00 0.71 1.13 O 2

2 2 K K 0.20 0.23 0.37 0.02 0.02 0.04 0.18 0.21 0.04 0.06 Si Si 2.94 2.94 2.89 2.47 2.44 2.60 2.64 2.66 2.61 2.6 Sr - - - 0.01 0.01 0.01 - - 0.01 - - Al Al Fe 1.07 - 1.06 0.01 1.04 0.11 1.53 0.03 1.56 0.03 1.39 0.04 1.36 0.02 1.35 0.02 1.40 0.03 1.3 0.01 0 Ba Ba ------Ca Ca 0.03 0.03 0.02 0.49 0.52 0.35 0.01 0.01 0.34 0.2 Na 0.77 0.77 0.68 0.46 0.44 0.60 1.14 1.04 0.60 0.6 SrO 0.04 0.02 - 0.35 0.28 0.18 0.01 0.03 0.18 0.15 FeO FeO 0.11 0.14 3.03 0.68 0.69 1.09 0.53 0.47 0.72 0. K BaO 0.04 0.09 0.03 0.09 0.07 0.15 -0.06 0.03 0.13 0 CaO CaO 0.69 0.56 0.42 10.18 10.74 7.34 0.09 0.21 7.09 Or% Or% 27.18 29.55 43.79 2.40 2.23 4.83 18.89 22.62 4. SiO An% An% Ab% 5.15 67.66 4.16 66.30 2.83 53.37 33.29 64.31 31.27 66.50 45.98 49.20 80.46 0.65 75.79 Total 101.64 100.34 102.63 100.51 100.75 100.78 86. Na Total 5.01 5.03 5.11 5.01 5.01 5.03 5.35 5.29 5.02 Al Note- Note- Mineral Mineral Position c r r c r c r c c c r Location Location Rock Rock Type Phnt Phnt Wt%oxide Sample Sample No. 139 139 139 139 139 41 41 41 41 179 179

Cations based on 8 oxygens. r= rim, c= core, mp= mi mp= c=core, rim, r= 8 oxygens. on based Cations 1. Table 122 as in

3 6 1 6 2 33 24 20 .77 1.46 5.01 0.03 2.26 11.43 72.93 69.53 lbite, Or-Ortoclase. and 25.76 29.01 es Mt. Rees Mt. Rees 2 2 52.22 53.41 65 29.99 29.14 .25 99.60 99.54 enmorite enmorite Benmorite Benmorite Benmorite eviations typesforrock and theare sameminerals 023 023 023 023 023

023 O withinminerals. O An-Anorthite, Abbreviation- Ab-A 2 of Na

r c cr cs r c r c crophenocrysts. below“-” detection Thelimit. abbr 023 023 Mt. Rees Mt. Rees Mt. Rees Mt. Rees Mt. Rees Mt. Rees Mt. Re

Af Af Pl Pl Pl Pl Pl Pl Pl Pl Pl Tphn Tphn Benmorite Benmorite Benmorite Benmorite B

K 0.20 0.11 0.02 0.01 0.02 0.01 0.02 0.01 0.01 0.01 Si Si 2.68 2.77 2.43 2.40 2.47 2.40 2.48 2.40 2.38 2.4 Sr - - 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 Al Al Fe 1.42 0.02 1.23 0.02 1.56 0.02 1.60 0.02 1.56 0.01 1.61 0.01 1.52 0.01 1.60 0.01 1.61 0.01 1.5 0.0 High values of High valuesoxides dueareconcentration to high Ba - 0.01 ------Ca Ca 0.04 0.19 0.56 0.59 0.54 0.60 0.51 0.58 0.60 0.5 Na Na 0.69 0.68 0.42 0.38 0.32 0.35 0.46 0.39 0.38 0.4 SrO 0.01 0.09 0.21 0.22 0.18 0.24 0.19 0.22 0.22 0. FeO 0.41 0.62 0.38 0.42 0.30 0.31 0.37 0.31 0.34 0. CaO CaO 0.77 BaO 4.08 -0.01 11.40 0.30 12.04 0.05 11.07 0.03 12.12 0.02 10.41 11.91 0.04 1 0.04 -0.02 0.03 Or% 28.43 14.12 1.71 1.33 1.67 1.47 1.82 1.22 1.31 K2O K2O 3.11 1.98 0.28 0.22 0.25 0.24 0.29 0.20 0.22 0. Ab% Ab% 64.53 56.78 28.87 25.92 24.18 24.08 32.75 26.38 An% An% 7.04 29.10 69.43 72.75 74.15 74.45 65.43 72.40 SiO2 SiO2 52.96 62.88 53.33 52.54 53.89 52.32 54.76 52.6 Total 5.06 5.01 5.01 5.00 4.92 4.98 5.00 5.00 5.01 Total 88.21 101.63 99.40 99.55 98.14 98.90 99.71 99 Na2O 7.06 7.96 4.74 4.29 3.61 3.92 5.21 4.34 4.33 4 Al2O3 Al2O3 23.88 23.73 29.01 29.78 28.81 29.71 28.43 29. Mineral Position c cs Location Location Boyd Boyd Rock Rock Type Wt% Wt% oxide Sample No.Sample 179 179 Note- Cationsbased oxygens.8on rim,r=c= core, mi mp= Table 1. 123 as in

.06 121 onolite 0.02 5.57 0.33 8 8.88 2 0.79 8 3 2.80 1.02 91 20 6.52 1.11 .01 0.02 lbite, Or-Ortoclase. and 5.28 5.24

.75 18.79 18.71 .14 59.98 60.84 eviations typesforrock and theare sameminerals 3 99.61 100.54 101.60 101.66 orrison Morrison Morison Morison Morison 5.27 3.31 4.23 2.93 7.56 7.13 64.32 62.22 62.94 71.11 57.18 57.07 30.42 34.46 32.84 25.96 35.26 35.80 honolite honolite Phonolite Phonolite Phonolite Phonolite Ph Ks Ks Ne O withinminerals. O An-Anorthite, Abbreviation- Ab-A Lc Lc 2 of Na crophenocrysts. below“-” detection Thelimit. abbr Af Af Af Af Af Ne Af Af Af Af Af Af Morrison Morrison Morrison Morrison Morrison Morrison Morrison M Phonolite Phonolite Phonolite Phonolite Phonolite P High values of High valuesoxides dueareconcentration to high 20.11 20.34 20.45 20.01 19.52 19.24 18.96 19.13 30 66.87 67.37 67.30 66.87 67.37 66.66 66.69 66.73 50 3 2 O O 7.23 8.32 8.42 6.89 6.15 8.67 8.45 8.49 13.12 9.0 O O 6.64 4.75 4.60 6.99 8.26 4.10 4.68 4.43 4.79 5.60 O 2

2 2 K K 0.37 0.27 0.26 0.40 0.47 0.23 0.27 0.25 0.28 0.33 Si 2.95 2.96 2.95 2.96 2.98 2.98 2.99 2.98 2.33 2.7 Sr ------Al Al Fe 1.05 0.01 1.05 0.01 1.06 0.01 1.04 0.01 1.02 0.02 1.01 - 1.00 0.01 1.01 1.69 - 1.0 0.04 0.27 0.25 Ba ------Ca Ca 0.01 0.02 0.02 0.01 - 0.03 0.02 0.03 0.03 0.06 0 Na 0.62 0.71 0.72 0.59 0.53 0.75 0.73 0.74 1.18 0.8 SrO 0.02 0.08 0.07 0.04 - 0.07 0.02 0.04 0.05 0.04 FeO 0.19 0.13 0.14 0.15 0.41 0.11 0.15 0.11 1.12 6. K BaO 0.23 0.11 0.16 0.19 0.04 0.09 0.13 0.10 0.03 -0 CaO CaO 0.28 0.41 0.52 0.27 0.02 0.71 0.45 0.57 0.54 1. SiO Or% 46.93 35.24 33.97 49.40 57.24 Ab% Ab% 51.10 61.72 62.19 48.69 42.62 An% An% 1.98 3.04 3.84 1.91 0.14 Total 101.56 101.49 101.65 101.41 101.77 99.65 99.5 Na Total 5.02 5.01 5.01 5.01 5.01 5.01 5.02 5.01 5.02 Al Note- Mineral Mineral Position r c c r r c c c cs cs cs Location Location Wt% oxide Wt%oxide Sample No. Sample 134 134 134 134 134 134 134 134 121 121 Type Rock

Cationsbased oxygens.8on rim,r=c= core, mi mp= Table 1. 124 es es as in as

4 -0.01

01 0.01 15 15 0.02 - Ortoclase. Ortoclase. - yte yte Trachyte Trachyte Albite, and Or Albite, and - 6.15 5.82 5.56 0.35 0.33 0.32 9 0 3 2.99 0.99 0.03 3.01 0.97 0.02 3.01 0.97 0.02 3 7.56 7.77 7.89 65 0.65 0.67 0.68 14 - 1.09 0.74 02 - 0.15 0.10 .83 0.92 0.46 0.42 5.02 5.01 5.01 5.00 Anorthite, Ab Anorthite, .82 19.10 19.10 18.35 18.39 .22 67.44 67.98 67.19 67.47 - An - eviations for rock types and minerals are the same same the are minerals and types forrock eviations 53.14 46.72 54.33 45.53 55.14 44.86 56.55 42.36 58.23 41.03 Mt.Rees Mt. Rees Mt.Rees Mt. Rees Mt.Rees Mt. Re Abbreviation 7 100.27 101.23 101.25 101.74 99.79 99.82 honolite honolite Phonolite Trachyte Trachyte Trachyte Trach O within minerals. minerals. within O 2 of Na crophenocrysts. “-” below detection limit. Theabbr limit. detection below “-” crophenocrysts. Af Af Af Af Af Af Af Af Af Af Af Af Af Af High values of oxides are due to high concentration to high due are of oxides values High Morison Morison Morison Morison Morison Morison Morison Morison Phonolite Phonolite Phonolite Phonolite Phonolite Phonolite P Note- Note- 20.68 20.73 19.87 18.00 17.77 20.97 20.34 18.61 18 66.70 66.71 67.11 54.98 53.65 66.59 66.61 67.51 67 3 2 O O 8.08 7.85 7.00 9.71 10.17 8.23 7.42 7.75 7.45 7.5 O O 4.97 5.33 7.04 6.09 5.56 4.46 5.84 5.85 6.55 6.31 O 2

2 2 K K 0.28 0.30 0.40 0.38 0.35 0.30 0.33 0.33 0.37 0.36 Si Si 2.99 2.93 2.96 2.68 2.64 2.92 2.94 3.01 2.99 2.9 Sr ------Al Al Fe 1.07 0.01 1.07 0.01 1.03 0.02 1.03 0.38 1.03 0.44 1.09 0.01 1.06 0.01 0.98 0.01 0.99 0.04 1.0 0.0 Ca Ca 0.03 0.03 0.01 0.06 0.08 0.04 0.03 0.01 - - - 0. Ba Ba ------Na 0.69 0.67 0.60 0.92 0.97 0.70 64.00 0.67 0.64 0. SrO 0.05 0.05 - - - 0.03 0.06 - 0.01 0.01 -0.01 0.0 FeO FeO 0.16 0.24 0.40 9.18 10.79 0.16 0.23 0.32 1.17 0 K BaO BaO 0.12 0.19 0.03 - - 0.21 0.10 0.02 -0.02 - 0.03 CaO CaO 0.70 0.69 0.30 1.06 1.47 0.93 0.56 0.20 0.02 0. Or% Or% 36.15 38.43 49.09 36.12 32.33 32.75 42.26 42.39 SiO An% An% 5.09 4.97 2.09 6.29 8.55 6.83 4.05 1.45 0.14 0. Ab% Ab% 58.76 56.60 48.81 57.59 59.13 60.43 53.69 56.16 Total 101.46 101.78 101.75 99.03 99.42 101.59 101.1 Na Total 5.05 5.02 5.02 5.45 5.51 5.01 5.01 5.01 5.03 Al Mineral Mineral Position Position c r r cs cs c r cs cs cs cs cs cs Location Rock Rock Type Wt%oxide Sample No.Sample 121 121 121 121 121 121 121 15 15 15 15 mi mp= c=core, rim, r= 8 oxygens. on based Cations Table 1. Table 125

.1 cs 014 iite iite Hawaiite

cs 2 2 1.27 0.11 1.19 0.24 9 0.94 0.85

ocrysts analyzed in lavas from the Crary Crary the from analyzed in lavas ocrysts .05 1.21 1.57 11.06 26.35 23.2 ameas in Table 1. 0.1 0.07 0.06 7 78 64.81 67.6 7 0.037 0.022 0.02

932 3.036 6.41 5.75 038 0.085 0.038 0.086 .531 0.447 0.611 0.585 .146 .201 0.88 0.183 0.46 0.256 0.61 0.238 76.2 77.7 74.1 74.8 19.7 19.6 24.9 25.1 93 93.93 92.86 94.77 94.73 22.602 21.571 23.809 17.533 18.632 82 82 27.774 27.461 28.484 25.336 25.923 ison ison Morison Mt. Rees Mt. Rees Mt. Rees Rees Mt.

honolite honolite Phonolite Phonolite Hawaiite Hawaiite Hawa titanomagnetite phenocrysts core-rims and microphen and core-rims phenocrysts titanomagnetite nocryst.The abbreviations for rock typesare thes TW92-’. TW92-’. icrophe 82.61 83.2 68.38 82.59 68.95 74.08 74.36 74.38 74.1 Moriosn Moriosn Moriosn Moriosn Moriosn Moriosn Morison Mor Phonolite Phonolite Phonolite Phonolite Phonolite Phonolite P t

Si Si 0.114 0.136 0.054 0.748 3.514 0 0.039 0.041 0.02 Ti 1.82 1.74 4.834 1.079 0.946 4.111 4.064 3.978 3. Al Al 0.16 0.228 1.492 0.479 2.812 0.428 0.429 0.414 1 Fe Fe 27.391 27.424 18.971 27.048 18.556 22.366 22.407 Ca Ca 0.074 0.067 0.085 0.116 0.039 0.033 0.02 0.01 0. Mg Mg 0.058 0.055 0.749 0.083 0.025 0.344 0.33 0.341 0 Mn Mn 0.37 0.359 0.176 0.381 0.242 0.392 0.392 0.388 0 CaO CaO 0.17 0.16 0.24 0.28 0.11 0.09 0.05 0.03 0.1 0.2 FeO SiO2 0.29 0.35 0.16 1.91 10.92 -0.64 0.11 0.11 0.08 MgO MgO 0.1 0.09 1.51 0.14 0.05 0.64 0.61 0.63 1.02 0.8 MnO MnO 1.1 1.08 0.62 1.15 0.89 1.28 1.29 1.26 0.68 0.5 Total 90.71 91.23 94.13 90.76 92.24 92.24 92.43 91. Total 29.987 30.01 26.364 29.934 26.134 27.675 27.6 TiO2 6.1 5.87 19.38 3.66 3.91 15.14 15 14.56 15.03 Al2O3 Al2O3 0.34 0.49 3.82 1.04 7.41 1.01 1.01 0.97 2.8 2 Sample Sample 134 134 134 134 134 121 121 121 014 014 014 Position c c c c c c c cs cs cs Location Location Rock type type Rock Ilmenite% 5.6 5.1 4.7 1.4 4.4 2.4 2 1.6 4.1 2.7 1 0 Magnetite% 82.1 82.4 74.5 81.8 74.4 77.3 77.4 77.6 Ulvospinel% Ulvospinel% 12.3 12.5 20.8 16.8 21.2 20.3 20.6 20.8

Mountains. All sample No.’s being with the prefix ‘ with the being No.’s sample All Mountains. APPENDIX 2.4.- Representative chemical analysis of of analysischemical Representative 2.4.- APPENDIX

Wt% oxide Wt%

Cationsbased on 32oxygens. r= rim,c= core, mp= m 126

Mt. Steere Tephrite

0.16

83 83 01 4.78 0.02 48 48 0.45 .53 7.99 Steere 0.044 0.05 27 62.06 62.73 012 0.004 0.008 .081 2.232 2.222 .866 .823 4.255 .236 3.119 0.126 4.29 2.937 0.119 ameas in Table 1. 74.2 19.7 73.1 22.1 72.2 20.4 6 96.26 95 94.95 4 24.51 18.24 18.29 17.646 17.639 16.101 16.367 64 25.696 25.689 26.055 26.126 t. Rees t. Rees Mt. Rees Rees Mt. Mt. e e Benmorite Benmorite Benmorite Benmorite Tephrite

nocryst.The abbreviations for rock typesare thes icrophe cs cs r c r c r r cs cs

cs 73.01 45.34 69.62 65.42 65.58 66.53 66.71 65.59 66. Mt. Rees Mt. Rees Rees Mt. Boyd Mt. Rees Mt. Rees Rees Mt. M t

Si Si 0 0.017 0.028 0.04 0.032 0.033 0.034 0.032 0.033 Ti 4.219 9.906 4.511 5.511 5.45 5.521 5.902 5.865 5 Al Al 1.331 0.067 1.076 1.24 1.376 1.027 0.843 0.813 0 Cr Cr 0.019 0 0.015 0 0.004 0.009 0.004 0.003 0 0 0 Fe Fe 20.819 10.706 19.448 17.677 17.616 18.015 17.847 Ca Ca 0.068 0.02 0.033 0.009 0.005 0.008 0.002 0.01 0. Mg Mg 0.466 1.036 1.587 1.083 1.09 1.059 0.747 1.092 1 Mn Mn 0.185 0.293 0.218 0.268 0.258 0.256 0.26 0.236 0 CaO CaO 0.19 0.06 0.09 0.03 0.01 0.02 0.01 0.03 0.03 0. FeO SiO2 -0.02 0.06 0.08 0.12 0.1 0.1 0.11 0.1 0.1 0.14 MgO MgO 0.92 2.46 3.19 2.25 2.28 2.19 1.57 2.28 2.28 4. MnO MnO 0.64 1.23 0.77 0.98 0.95 0.93 0.96 0.87 0.88 0. Total 27.106 22.044 26.916 25.829 25.829 25.928 25. Total 94.59 96.02 94.5 94.74 95.13 95.19 96.13 95.2 TiO2 16.45 46.66 17.96 22.68 22.56 22.67 24.53 24.2 Al2O3 3.31 0.2 2.73 3.26 3.63 2.69 2.24 2.14 2.19 8 Sample Sample 014 014 139 023 023 023 023 023 023 169 169 Position cs Location Location Ilmenite% 1.1 7.9 0.8 2.8 5.8 3 4.8 4.8 6.1 4.8 7.4 Magnetite% 79.3 67.8 77.8 75.6 74.1 74.9 74.6 74.1 Ulvospinel% Ulvospinel% 19.6 24.3 21.4 21.6 20.1 221 20.6 21.1 Rock typeRock Hawaiite Hawaiite Phnt Benmorite Benmorit

Wt% oxideWt%

Cationsbased on 32oxygens. r= rim,c= core, mp= m 127

argasite argasite Morrison

onolite Phonolite Morrison

3.80 4.11 4.29 Morrison

1.95 1.96 1.97 0.82 0.85 0.79 0.16 0.17 0.15 2.87 2.93 2.87 4 8 9 6.04 3 0.44 4 2.28 6 6.01 0.04 1 0.47 2.35 4 2.29 5.98 1.94 0.04 0.49 1.78 2.19 2.33 0.85 2.07 0.04 1.80 2.14 0.87 2.07 1.82 0.84 3 0.03 0.03 0.03 25 0.27 0.28 0.28 .07 8.51 9.12 9.16 sbased on the classificationscheme of Morrison analyzed in lavas from the Crary Crary lavasinthe analyzed from

13 35.02 31.59 34.68 35.18 .55 12.78 12.68 12.79 13.03 .26 39.70 39.56 39.50 39.36 Morrison

18.04 16.83 18.43 17.18 16.88 10.73 11.08 10.90 11.01 11.15 84 18.25 17.84 17.89 17.89 17.87 83 102.06 99.61 99.88 99.78 99.82 ag.sioh. Ferropar Pargasite Hastingsite Pargasite P Morrison

honolite honolite Phonolite Phonolite Phonolite Phonolite Ph Morrison

Morrison phibole phenocrysts and microphenocrysts core-rims core-rims microphenocrysts and phenocrysts phibole Morrison sing program the developed by Esawi (2004), whichi TW92-’.

ctionlimit. Morrison

Ferr. Sche Sche Hastingsite Mag.sioh. Kaersutite Hastingsite M Morrison

134 134 134 134 134 134 134 134 134 134 134 134 Phonolite Phonolite Phonolite Phonolite Phonolite Phonolite P Morrison Morrison 10.98 10.25 10.95 10.91 12.68 13.25 12.62 12.87 12 1.75 2.23 1.74 1.86 4.04 4.57 3.87 4.29 3.71 4.24 38.30 39.31 38.10 38.36 39.55 39.56 39.48 39.86 40 3 2 2 O 2.69 2.90 1.26 2.80 2.19 2.70 2.90 2.87 5.03 2.86 O 1.81 1.83 1.78 1.81 1.95 1.98 1.95 1.97 1.98 1.97 O 1.32 1.23 1.36 1.42 0.81 0.76 0.78 0.79 0.85 0.79 O 2

2 2 2 K K 0.28 0.25 0.29 0.30 0.16 0.15 0.15 0.15 0.16 0.15 Si 6.26 6.34 6.31 6.25 6.06 5.96 6.04 6.03 6.04 6.0 Ti 0.22 0.27 0.22 0.23 0.47 0.52 0.45 0.49 0.42 0.4 Cl Cl 0.11 0.10 0.11 0.10 0.02 0.03 0.03 0.03 0.05 0.0 Al Al Fe 2.12 3.93 1.95 3.76 2.14 4.03 2.10 3.99 2.29 2.29 2.35 1.90 2.28 2.32 2.30 2.09 2.22 2.26 2.2 2.1 Ca Ca 1.80 1.78 1.81 1.75 1.79 1.80 1.80 1.76 1.73 1.8 Na 0.85 0.91 0.40 0.89 0.65 0.79 0.86 0.84 1.46 0.8 Mn Mg 0.08 0.52 0.08 0.67 0.09 0.49 0.08 0.49 0.04 2.00 0.03 2.33 0.04 1.96 0.04 2.14 0.04 1.91 0.0 2.0 FeO 28.74 27.83 29.08 29.30 17.86 15.12 18.10 16.51 H K CaO CaO 10.29 10.29 10.23 10.03 10.87 11.17 10.95 10.84 Mg# Mg# 6.87 9.05 6.44 6.45 32.88 40.66 32.24 36.55 32. SiO TiO MnO MnO 0.60 0.56 0.62 0.59 0.27 0.23 0.29 0.28 0.32 0. MgO MgO 2.12 2.77 2.00 2.02 8.75 10.36 8.61 9.51 8.54 9 Total 18.05 18.01 17.77 18.08 17.74 17.82 17.89 17. Total 98.71 99.31 97.24 99.21 98.99 99.75 99.59 99. Na APPENDIX-2.5 Representative chemical analysis of am analysisof chemical Representative APPENDIX-2.5 ‘ prefix with the being No.’s sample Mountains. All Al Name Name Hastingsite Ferropar Sample Sample 134 Position c c c c c c r r c c c r r Location Location Rock Type Rock Phonolite Wt%oxide

Cationbased on 23 oxygens. Amphiboles named are u Leake et 1997. al., r= rim, core.c= “-” below dete 128 ., ., 23 23 hyte hyte Benmorite Benmorite Rees Rees Mt.Rees Mt.Rees rroged rroged Ferroged Kaersutite 0.10 5.38 5.16 1.54 1.98 1.97 0.00 0.92 0.93 0.00 0.18 0.18 0 0.00 0.00 0.00 2 1 0 5.82 4 0.01 0.00 4 6.04 0.67 9 0.61 0 2.06 0.15 6.11 0.04 0.21 0.59 0.01 2.00 2.11 0.04 1.86 0.83 2.08 1.85 0.82 01 0.02 2.83 2.77 29 49 4.03 0.51 0.33 9.36 0.33 9.16 0.47 10.32 2.10 2.14 174 174 .48 -0.01 -0.01 11.52 11.15 .28 29.83 29.80 39.83 40.14 s based on the classification scheme of Leake et al et Leake of scheme classification the on based s 6.74 0.76 0.80 36.15 35.27 1.26 0.88 1.00 11.43 11.33 16.53 64.15 63.20 16.53 16.81 83 17.81 19.17 19.17 17.83 17.80 100.60 100.42 100.23 100.18 100.11 99.76 . Rees . Rees Mt.Rees Mt.Rees Mt. Rees Mt. Rees Mt. nmorite nmorite Benmorite Benmorite Benmorite Trachyte Trac e e Ferrokae Ferrokae Tscherm. Kaersutite Ferroged Fe sing the program developed by Esawi (2004), which i which (2004), Esawi by developed program the sing

23 23 23 23 23 23 ” below detection limit. detection ”below - Morrison Mt.Rees Mt.Rees Mt. Rees Mt. Rees Mt Phonolit Phonolit e Trachyte Trachyte Benmorite Benmorite Be 13.09 -0.01 -0.01 11.52 11.15 11.39 11.34 11.37 11 3.83 0.04 0.10 5.38 5.16 5.07 5.30 5.17 5.26 0.04 39.14 29.83 29.80 39.83 40.14 40.08 40.15 40.37 40 3 2 2 O O 2.86 -0.01 0.02 2.83 2.77 2.75 1.38 2.93 2.83 -0. u named are Amphiboles oxygens. 23 on based Cation “ core. c= rim, r= 1997. O O 1.95 1.54 1.54 1.98 1.97 1.97 1.97 1.99 1.99 1.54 O O 0.88 0.00 0.00 0.92 0.93 0.95 0.88 0.86 0.90 0.00 O 2

2 2 2 K K 0.17 0.00 0.00 0.18 0.18 0.18 0.17 0.17 0.17 0.00 Si Si 5.98 5.82 5.82 6.04 6.11 6.09 6.12 6.08 6.07 5.8 Cl Cl 0.04 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0 Ti 0.44 0.01 0.01 0.61 0.59 0.58 0.61 0.59 0.60 0.0 Al Al 2.36 0.00 0.00 2.06 2.00 2.04 2.04 2.02 2.04 0.0 Fe 2.30 10.47 10.32 2.10 2.14 2.12 2.10 2.10 2.08 1 Ca Ca 1.75 0.19 0.21 1.86 1.85 1.85 1.90 1.84 1.82 0.1 Na Na 0.85 0.00 0.01 0.83 0.82 0.81 0.41 0.86 0.83 0.0 Mn Mn Mg 0.04 2.02 0.54 0.14 0.67 0.15 0.04 2.11 0.04 2.08 0.04 2.09 0.04 2.15 0.04 2.15 0.04 2.16 0.5 0.1 FeO 18.00 64.15 63.20 16.53 16.81 16.68 16.48 16.63 H K CaO 10.68 0.88 1.00 11.43 11.33 11.35 11.63 11.38 1 SiO Mg# Mg# 32.96 0.76 0.80 36.15 35.27 35.57 36.49 36.55 3 TiO Type MnO MnO 0.32 3.29 4.03 0.33 0.33 0.31 0.29 0.32 0.30 3. MgO MgO 8.85 0.49 0.51 9.36 9.16 9.21 9.47 9.58 9.60 0. Rock Rock Total 99.65 100.23 100.18 100.11 99.76 99.75 98.88 Total 17.91 19.17 19.17 17.83 17.80 17.80 17.54 17. Na Name Name Mag.sioh. Ferroged Ferroged Ferroged Kaersutit Al Sample 134 174 174 Position Position c c r c r r c r r c r c r Location Location Wt% Wt% oxide

129 d ., ., hyte hyte Mt. Rees 0.14 0.02 0.32 0.00 6.69 0.02 1.51 -0.01 1.81 1.53 8 4 3 8.12 5 0.02 4 0.03 2 5.83 0.14 4 0.00 4.81 6 0.00 0.00 0.51 0.51 10.51 2.14 0.12 0.18 0.01 4 0.03 0.00 05 1.03 3.10 .17 0.13 .07 0.01 0.00 0.42 5 0.20 0.00 0.65 4 3.04 2.88 0.87 .85 49.81 49.33 29.80 34.31 34.53 34.98 64.26 s based on the classification scheme of Leake et al et ofLeake scheme classification the on based s 04 18.65 17.84 18.08 19.17 98 102.03 98.06 98.57 100.02 chyte chyte Trachyte Trachyte Trachyte Trachyte Trachyte Trac . Rees . Rees Rees Mt. Mt. Rees Mt. Rees Rees Mt. Mt. Rees ic ic Arfvedso. Ferroric Ferroric Ferroric Ferroric Ferroric Ferroge sing the program developed by Esawi (2004), which i which (2004), Esawi by developed program the sing

” below detection limit. detection below ” - Phonolite Phonolite Phonolite Phonolite Trachyte Tra 13.09 13.64 12.77 13.12 0.13 0.14 0.16 0.14 0.14 0 3.83 3.83 3.94 4.04 0.47 0.18 0.56 0.44 0.34 0.34 39.14 39.39 39.42 39.18 49.85 49.74 49.50 49.88 49 3 2 2 O 2.86 2.78 2.61 3.44 7.04 7.13 6.74 6.87 9.87 5.83 O 0.88 0.70 0.85 0.82 1.42 1.48 1.39 1.43 1.40 1.37 O 1.95 1.98 1.95 1.95 1.83 1.82 1.82 1.83 1.87 1.82 O 2

2 2 2 K 0.17 0.14 0.17 0.16 0.30 0.31 0.29 0.30 0.29 0.29 Si Si 5.98 5.96 6.04 5.98 8.12 8.14 8.12 8.13 7.97 8.1 Ti 0.44 0.44 0.45 0.46 0.06 0.02 0.07 0.05 0.04 0.0 Cl Cl 0.04 0.02 0.04 0.05 0.03 0.05 0.03 0.04 0.03 0.0 Al Al 2.36 2.43 2.30 2.36 0.03 0.03 0.03 0.03 0.03 0.0 Fe Fe 2.30 2.02 2.36 2.28 4.64 4.72 4.67 4.66 4.59 4.7 Ca 1.75 1.69 1.80 1.76 0.55 0.50 0.52 0.53 0.54 0.5 Na 0.85 0.82 0.78 1.02 2.23 2.26 2.15 2.17 3.06 1.8 Mn Mn Mg 0.04 2.02 0.03 2.36 0.04 1.91 0.04 1.91 0.15 0.01 0.14 0.00 0.15 0.02 0.14 0.02 0.14 0.01 0.1 0.0 FeO 18.00 15.95 18.41 17.82 34.09 34.48 34.02 34.21 K H CaO CaO 10.68 10.40 10.95 10.76 3.14 2.85 2.98 3.02 3.1 SiO Mg# Mg# 32.96 39.61 31.23 32.04 0.15 0.03 0.21 0.23 0.1 TiO Type MnO MnO MgO 0.32 8.85 0.27 10.46 0.29 8.36 0.33 8.40 1.05 0.05 1.01 0.01 1.10 0.07 1.03 0.08 1.03 0.05 1. 0 Rock Rock Total 17.91 17.87 17.83 17.97 18.07 18.12 18.02 18. Total 99.65 99.41 99.60 99.92 99.13 98.93 98.39 98. Na Al Name Mag.sioh. Mag.sioh. Hastingsite Mag.sioh. Ferror Sample Sample 134 134 134 134 15 15 15 15 15 15 15 174 Position c c r r r c r r c r c c1 Location Location Morrison Morrison Morrison Morrison Mt. Rees Mt Wt% oxideWt% u named are Amphiboles oxygens. 23 on based Cation “ core. c= rim, r= 1997. 130

7 7 1 2 2

16 - - c Benmorite m the Crary Mountains. All sample Crarythe Mountains. Allm sample No.’s 82 53.13 .75 42.09 - - 11 96.41 100.03 - - - - on on Morrison Morrison Morrison Mt. Rees - -

- - honolite honolite Phonolite Phonolite Phonolite Phonolite atite phenocrysts and microphenocrysts in lavasfro in andmicrophenocrysts phenocrysts atite - - - - ” indicates belowdetection limit. - - -

Morrison Morrison Morrison Morrison Morrison Morris 38.91 37.19 39.16 39.85 38.52 39.14 38.58 38.34 37 0.64 1.93 -0.11 0.19 0.72 0.18 0.19 0.24 0.27 0.09 0.01 0 - - 0.01 0.01 0 0.02 - 0.01 5 2 2 O -

O 2 F F 5.31 4.88 6.06 5.74 5.39 5.57 5.19 5.08 5.61 4.04 2 Cl Cl 0.04 0.06 0.03 0.05 0.04 0.07 0.04 0.04 0.11 0.2 SO SrO 0.01 0.03 0.11 0.15 0.13 0.13 0.11 0.08 0.11 0. FeO FeO 0.86 0.8 0.62 0.49 1.54 0.33 0.45 0.56 0.66 0.2 H CaO CaO 52.3 50.95 52.67 53.19 52.87 53 52.63 52.66 51. SiO P MnO 0.09 0.07 0.09 0.05 0.08 0.12 0.1 0.09 0.08 0.0 Total 98.16 95.93 98.74 99.71 99.29 98.54 97.28 97. Sample Sample 121 121 121 121 121 121 121 121 121 23 Position c r c c c c c c c Location Rock type Phonolite Phonolite Phonolite Phonolite P Wt% oxide APPENDIX 2.6-Representative chemical ap ofanalyses chemical 2.6-Representative APPENDIX c=core, r= rim, =microphenocrysts.mp “ being with the prefixthe with ‘TW92-’. being 131

ection limit.ection ” indicates belowdet - c c r c c c Mt. Rees Mt. Rees Mt. Rees Mt. Rees Mt. Rees Benmorite Benmorite Benmorite Benmorite Benmorite

0.03 42.2 40.88 41.76 41.29 34.38 0.13 0.32 0.33 0.53 0.01 -0.01 0.02 0.01 0.01 5 2 2 O 1.18 - - - -

O 2 F F - 4.18 4.3 4.01 4.47 2 Cl Cl 0 0.21 0.24 0.24 0.15 SO SrO - 0.14 0.13 0.12 0.12 FeO FeO 34.57 0.29 0.84 1.3 1.37 H CaO CaO 0.35 53.78 53.39 53.46 53.05 SiO P Wt% MnO MnO 0.75 0.06 0.04 0.05 0.12 Total 71.27 101 100.15 101.26 101.1 oxide Sample Sample 23 23 23 23 23 Position Location Location Rock type

c=core, r= rim, =microphenocrysts.mp “ 132

1 4.9 Mt. Rees Rees Trachyte

3 6.95 .51 0.34 Mt. 0.01 0.02 Rees Rees Trachyte

86 0.84 0.88 Mt. Rees Rees Trachyte

s from the Crary Mountains. All sample Allsample Mountains. Crary the from s 8 8 0.2 0.47 0.31 .93 40.66 40.36 40.72 Mt. Rees Rees 41.78 42.04 42.43 42.49 Trachyte

61 99.06 97.64 98.8 96.68 Mt. Rees Rees Trachyte

Mt. Rees Rees Trachyte

Mt.

Rees Rees Trachyte

c c c r c r r c r enigmatite phenocrysts and microphenocrysts in lava and phenocrysts enigmatite s below detection limit. detection below s Trachyte

c Trachyte

c -’. Trachyte Mt. Rees Mt. Rees Mt. Rees Mt.

Mt. Rees Rees Trachyte 0.31 0.27 0.29 0.16 0.39 0.23 0.36 0.28 0.18 0.2 0 0.46 0.4 0.52 0.3 6.44 6.99 7.36 6.82 6.9 6.62 7.1 0.01 0.01 - - 0.03 - 0.04 -0.02 0.02 0.01 0.02 0.0 48.21 48.06 48.09 50.42 40.67 41.39 40.97 41.26 41 3 2 5 2 O - 1.34 - 6.67 7.01 7.17 7.05 7.19 7.18 6.97 6.98 O 0.02 0 0.03 0.01 0.01 - 0.01 0.02 - 0.02 0 0.01 O 2

O 2 2 2 FeO 29.1 28.89 28.94 29.27 42.55 41.73 41.59 41.92 K CaO CaO 18.81 18.77 18.59 10.56 0.35 0.29 0.34 0.25 0.1 SiO P TiO MgO MgO 0.19 0.19 0.14 0.02 0.01 0.03 0.02 0 0.03 0.01 MnO MnO 0.99 1.05 1.09 0.67 0.86 0.81 0.86 0.87 0.85 0. Total 98.07 98.99 97.71 98.07 98.36 98.65 98.66 98. Na Al Position c Location Location Wt% oxide Rocky Rocky type Sample No.Sample 15 15 15 15 15 15 15 15 15 15 15 15

c= core, r= rim, mp =microphenocrysts. “-” indicate“-” rim, mp r= =microphenocrysts. core, c= a of analyses chemical APPENDIX-2.7.-Representative prefixthe with being No.’s ‘TW92 133

es te Trachyte s below detection limit. detection below s Mt. Rees Mt. Rees Mt. Rees Rees Mt. Mt. Rees Rees Mt. Mt. Re r r r r r c c Rees Rees Trachyte Trachyte Trachyte Trachyte Trachyte Trachyte Trachy 0.54 0.35 0.58 -0.01 0.37 0.41 0.54 0.43 0.43 0.49 0.09 0.02 0.21 - 0.4 0.47 - 0.06 0.07 - 0.01 47.84 48.33 47.99 30.07 35.86 48.4 48.28 3 2 5 2 O 2.36 1.08 0.89 0.03 0.32 0.08 1.01 O 0.01 0.02 0.03 -0.02 0.24 0.02 0.06 O 2

O 2 2 2 No. 174 174 174 174 174 174 174 FeO 29.02 29.21 28.19 61.75 54 28.98 28.82 K CaO CaO 18.4 17.71 18.74 0.27 0.56 18.59 18.47 SiO P TiO Wt% Type Rock Rock MnO MnO 1.15MgO 0.63 1.17 1.18 0.5 5.27 0.61 0.23 0.71 1.2 0.02 0.64 1.21 0.65 Total 100.4 98.82 98.74 98.29 92.78 98.75 99.52 oxide oxide Na Al Sample Sample Position Location Location Mt.

c= core, r= rim, mp =microphenocrysts. “-” indicate “-” r= =microphenocrysts. mp rim, core, c=

134

APPENDIX 3.- Major (wt%) and trace (ppm) element analyses of lavas from the Mount Steere and Mount Rees, volcanoes, Crary Mountains, Antarctica.

SAMPLE TW92009 TW92014 TW92015 TW92025 TW92033 TW92045 TW92052 LOCATION Trab. Cliff Trab. Cliff Rees Tasch Rees Trab. Cliff Wilchland AGE - 9.01 - - 8.00 - NAME Mugearite Hawaiite Trachyte Phon.teph. Phon. Tephrite Phon.teph. (TAS) teph.

SiO 2 52.26 44.70 65.82 52.13 49.61 42.22 49.84

TiO 2 1.82 3.49 0.34 1.61 1.91 2.80 1.40

Al 2O3 16.02 15.85 14.20 17.81 18.57 16.37 15.73 FeO t 12.79 15.34 6.34 9.81 9.83 14.50 10.76 MnO 0.23 0.23 0.16 0.23 0.19 0.19 0.28 MgO 2.12 4.80 0.00 2.01 2.17 6.81 1.37 CaO 5.41 9.29 0.80 5.35 6.88 11.64 5.54

Na 2O 5.25 3.98 7.20 6.43 5.53 2.55 5.70

K2O 2.77 1.03 4.86 2.79 2.36 0.59 3.11

P2O5 0.71 0.45 0.00 0.54 0.75 0.25 0.38 LOI 0.95 1.10 0.23 1.49 2.13 1.62 6.04 TOTAL 100.34 100.27 99.96 100.21 99.92 99.53 100.15 Q 0.00 0.00 7.00 0.00 0.00 0.00 0.00 Or 17.00 6.00 29.00 17.00 14.00 4.00 20.00 Ab 45.00 27.00 48.00 41.00 37.00 15.00 37.00 Ne 2.00 6.00 0.00 11.00 8.00 5.00 11.00 Hy 0.00 0.00 4.00 0.00 0.00 0.00 0.00 Ol 8.00 9.00 0.00 5.00 5.00 13.00 4.00 Di 8.00 17.00 3.00 9.00 8.00 21.00 14.00 Ac 0.00 0.00 5.00 0.00 0.00 0.00 0.00 Mg# 14.22 23.83 0.00 17.01 18.08 31.96 11.29

Cl 57.00 185.00 0.00 795.00 400.00 112.00 67.00 S 59.00 476.00 51.00 81.00 88.00 197.00 504.00 V 10.00 211.00 0.00 12.00 56.00 349.00 12.00 Cr 0.00 1.00 2.00 1.00 6.00 35.00 0.00 Ni 5.00 9.00 4.00 6.00 5.00 59.00 3.00 Cu 17.00 26.00 4.00 23.00 27.00 80.00 14.00 Zn 119.00 108.00 207.00 79.00 75.00 87.00 127.00 Ga 22.00 21.00 33.00 23.00 19.00 20.00 21.00 Rb 64.00 25.00 191.00 77.00 55.00 15.00 93.00 Sr 509.00 686.00 4.00 572.00 838.00 605.00 396.00 Y 48.00 31.00 78.00 44.00 35.00 22.00 49.00 Zr 308.00 191.00 986.00 402.00 308.00 115.00 337.00 Nb 72.00 48.00 160.00 112.00 82.00 28.00 106.00 Ba 678.00 309.00 18.00 738.00 668.00 174.00 840.00 La 64.00 36.00 157.00 90.00 54.00 11.00 69.00 Ce 139.00 76.00 335.00 149.00 110.00 33.00 134.00 Nd 50.00 31.00 111.00 53.00 37.00 16.00 56.00 Pb 14.00 10.00 28.00 12.00 11.00 11.00 11.00 Th 12.00 2.00 42.00 10.00 3.00 4.00 10.00 135

SAMPLE TW92055 TW92056 TW92063 TW92072 TW92078 TW92080 TW92081 LOCATION Wilchland Wilchland Mt. Mt. Lie Cliff Lie Cliff Lie Cliff Steere Steere AGE - - 8.27 - - 7.82 - NAME Hawaiite Mugearite Trachyte Hawaiite Mugearite Trachyte Alk. (TAS) Basalt

SiO 2 48.29 48.50 60.10 48.83 48.85 60.65 42.25

TiO 2 2.04 1.90 0.31 2.92 2.66 0.39 1.95

Al 2O3 20.86 18.41 16.87 16.81 16.91 16.07 14.43 FeO t 9.08 11.09 7.30 12.63 12.70 8.35 12.23 MnO 0.16 0.16 0.20 0.21 0.21 0.31 0.17 MgO 2.53 2.46 0.13 3.23 2.98 0.08 8.60 CaO 9.46 7.48 1.42 7.89 7.32 1.26 9.81

Na 2O 4.21 4.59 6.46 4.25 4.85 6.71 3.38

K2O 1.31 1.70 5.38 1.96 1.56 5.30 0.75

P2O5 0.64 0.70 0.02 0.63 0.55 0.02 0.28 LOI 1.13 3.34 1.92 1.02 1.70 0.77 6.21 TOTAL 99.70 100.33 100.11 100.38 100.30 99.92 100.07 Q 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Or 8.00 10.00 32.00 12.00 10.00 31.00 5.00 Ab 35.00 40.00 53.00 38.00 41.00 52.00 17.00 Ne 2.00 2.00 3.00 1.00 3.00 3.00 9.00 Hy 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Ol 5.00 7.00 3.00 6.00 7.00 5.00 17.00 Di 7.00 7.00 5.00 12.00 11.00 5.00 21.00 Ac 0.00 0.00 0.00 0.00 0.00 3.00 0.00 Mg# 21.79 18.15 1.75 20.37 19.01 0.95 41.29

Cl 165.00 34.00 56.00 207.00 165.00 4.00 352.00 S 50.00 56.00 71.00 135.00 144.00 52.00 155.00 V 97.00 68.00 12.00 107.00 134.00 13.00 194.00 Cr 5.00 8.00 3.00 1.00 0.00 0.00 392.00 Ni 3.00 18.00 5.00 8.00 6.00 4.00 152.00 Cu 25.00 32.00 8.00 33.00 34.00 14.00 89.00 Zn 56.00 67.00 142.00 91.00 94.00 202.00 79.00 Ga 20.00 18.00 37.00 21.00 21.00 32.00 15.00 Rb 30.00 38.00 172.00 49.00 28.00 141.00 20.00 Sr 996.00 844.00 31.00 741.00 699.00 11.00 431.00 Y 26.00 34.00 100.00 37.00 37.00 81.00 24.00 Zr 177.00 267.00 863.00 242.00 267.00 454.00 134.00 Nb 50.00 65.00 176.00 66.00 67.00 188.00 33.00 Ba 391.00 552.00 269.00 523.00 592.00 167.00 258.00 La 40.00 63.00 128.00 48.00 51.00 143.00 13.00 Ce 63.00 117.00 281.00 98.00 104.00 291.00 49.00 Nd 32.00 50.00 79.00 44.00 35.00 71.00 33.00 Pb 12.00 8.00 28.00 13.00 11.00 20.00 8.00 Th 2.00 3.00 28.00 5.00 6.00 28.00 2.00

136

SAMPLE TW92086 TW92088 TW92089 TW92095 TW92112 TW92118 LOCATION Lie Cliff Lie Cliff Lie Cliff Mt. Steere Mt. Rees Mt. Rees AGE 8.52 - - 5.74 9.02 7.55 NAME (TAS) Hawaiite Hawaiite Phonolite Rhyolite Trachyte Phonolite

SiO 2 45.83 45.61 55.91 52.81 59.47 60.17

TiO 2 2.74 2.91 0.08 1.52 0.44 0.08

Al 2O3 15.97 15.45 18.90 16.33 17.37 18.60 FeO t 14.73 15.73 5.27 13.18 8.06 4.99 MnO 0.24 0.25 0.19 0.26 0.24 0.17 MgO 4.59 3.89 0.00 2.09 0.29 0.00 CaO 9.26 8.52 0.69 5.21 2.57 0.76

Na 2O 4.42 4.53 9.62 5.65 7.08 9.69

K2O 1.03 1.23 4.86 2.36 4.40 4.95

P2O5 0.40 0.42 0.01 0.93 0.09 0.01 LOI 0.85 1.55 4.40 0.61 0.00 0.51 TOTAL 100.06 100.09 99.93 99.73 99.99 99.93 Q 0.00 0.00 0.00 0.00 0.00 0.00 Or 6.00 8.00 29.00 14.00 26.00 28.00 Ab 27.00 29.00 36.00 49.00 52.00 44.00 Ne 8.00 8.00 23.00 2.00 7.00 15.00 Hy 0.00 0.00 0.00 0.00 0.00 0.00 Ol 9.00 9.00 3.00 10.00 3.00 2.00 Di 19.00 18.00 3.00 6.00 8.00 3.00 Ac 0.00 0.00 4.00 0.00 0.00 4.00 Mg# 23.76 19.83 0.00 13.69 3.47 0.00

Cl 67.00 173.00 148.00 33.00 605.00 2401.00 S 99.00 64.00 51.00 56.00 50.00 49.00 V 234.00 210.00 14.00 16.00 2.00 2.00 Cr 6.00 0.00 2.00 0.00 4.00 8.00 Ni 15.00 8.00 4.00 8.00 3.00 1.00 Cu 35.00 22.00 14.00 26.00 11.00 8.00 Zn 104.00 112.00 172.00 78.00 103.00 134.00 Ga 19.00 20.00 35.00 23.00 32.00 25.00 Rb 24.00 34.00 202.00 62.00 96.00 189.00 Sr 590.00 596.00 2.00 641.00 220.00 8.00 Y 31.00 33.00 74.00 49.00 68.00 39.00 Zr 164.00 177.00 1075.00 352.00 551.00 834.00 Nb 45.00 49.00 245.00 79.00 137.00 154.00 Ba 312.00 336.00 44.00 685.00 2151.00 194.00 La 26.00 33.00 187.00 75.00 101.00 136.00 Ce 58.00 69.00 332.00 132.00 214.00 227.00 Nd 20.00 25.00 87.00 45.00 66.00 46.00 Pb 9.00 10.00 23.00 13.00 19.00 23.00 Th 4.00 5.00 29.00 12.00 16.00 37.00

137

SAMPLE TW92121 TW92122 TW92125 TW92127 TW92128 TW92130 LOCATION Mt. Rees Mt. Rees Morrison Morrison Morrison Morrison AGE 4.18 4.17 2.54 4.25 2.52 3.88 NAME (TAS) Phonolite Phonolite Hawaiite Phonolite Hawaiite Alk. Basalt

SiO 2 55.62 55.88 47.08 55.71 46.45 46.75

TiO 2 0.41 0.42 2.33 0.39 2.29 2.33

Al 2O3 19.54 19.65 15.90 19.61 16.13 15.92 FeO t 6.80 6.76 12.57 6.73 12.69 12.76 MnO 0.24 0.24 0.19 0.24 0.19 0.19 MgO 0.33 0.33 7.32 0.36 7.22 7.76 CaO 1.30 1.34 9.35 1.29 9.18 9.24

Na 2O 9.92 10.70 3.78 9.46 4.05 3.82

K2O 4.77 4.77 1.29 4.89 1.22 1.12

P2O5 0.10 0.10 0.46 0.09 0.50 0.46 LOI 0.60 0.05 0.10 0.85 0.01 0.48 TOTAL 99.63 100.23 100.37 99.63 99.92 99.87 Q 0.00 0.00 0.00 0.00 0.00 0.00 Or 27.00 27.00 8.00 28.00 7.00 7.00 Ab 30.00 28.00 26.00 30.00 25.00 26.00 Ne 28.00 28.00 5.00 28.00 7.00 5.00 Hy 0.00 0.00 0.00 0.00 0.00 0.00 Ol 4.00 4.00 14.00 4.00 14.00 15.00 Di 4.00 5.00 17.00 5.00 16.00 16.00 Ac 5.00 5.00 0.00 5.00 0.00 0.00 Mg# 4.63 4.65 36.80 5.08 36.26 37.82

Cl 1190.00 1042.00 217.00 487.00 161.00 262.00 S 85.00 94.00 73.00 162.00 101.00 68.00 V 7.00 10.00 188.00 10.00 174.00 180.00 Cr 6.00 5.00 260.00 6.00 245.00 265.00 Ni 6.00 3.00 111.00 5.00 104.00 112.00 Cu 9.00 9.00 64.00 9.00 61.00 53.00 Zn 144.00 141.00 86.00 146.00 80.00 82.00 Ga 35.00 34.00 18.00 34.00 17.00 19.00 Rb 157.00 153.00 32.00 158.00 30.00 27.00 Sr 61.00 69.00 556.00 55.00 586.00 594.00 Y 86.00 87.00 32.00 88.00 31.00 30.00 Zr 860.00 852.00 191.00 866.00 191.00 177.00 Nb 276.00 273.00 49.00 279.00 46.00 44.00 Ba 393.00 426.00 337.00 371.00 340.00 320.00 La 137.00 131.00 27.00 131.00 30.00 30.00 Ce 248.00 243.00 61.00 258.00 61.00 63.00 Nd 68.00 64.00 34.00 69.00 25.00 28.00 Pb 17.00 16.00 12.00 16.00 12.00 11.00 Th 34.00 32.00 6.00 34.00 2.00 4.00

138

SAMPLE TW92134 TW92135 TW92142 TW92145 TW92148 TW92151 LOCATION Morrison Runyon Morrison Morrison Morrison English rock AGE - 2.67 1.82 1.81 - 0.03 NAME (TAS) Phonolite Hawaiite Alk. Basalt Alk. Basalt Alk. Basalt Basanite

SiO 2 60.25 47.53 46.23 47.43 47.04 46.44

TiO 2 0.09 1.90 1.78 1.77 1.77 2.55

Al 2O3 19.45 16.91 14.49 14.83 14.89 15.94 FeO t 3.76 12.15 11.69 11.62 11.49 12.34 MnO 0.15 0.22 0.20 0.20 0.20 0.19 MgO 0.01 5.90 10.42 9.75 9.37 7.40 CaO 0.89 8.69 10.65 9.93 10.10 8.79

Na 2O 9.58 4.86 3.26 3.63 3.69 4.48

K2O 4.80 1.47 1.04 1.20 1.22 1.66

P2O5 0.03 0.47 0.31 0.31 0.31 0.60 LOI 1.07 0.05 0.29 0.46 0.26 0.51 TOTAL 100.07 100.14 99.77 100.21 99.81 99.89 Q 0.00 0.00 0.00 0.00 0.00 0.00 Or 27.00 9.00 6.00 7.00 7.00 10.00 Ab 45.00 25.00 17.00 21.00 20.00 22.00 Ne 18.00 11.00 7.00 7.00 8.00 11.00 Hy 0.00 0.00 0.00 0.00 0.00 0.00 Ol 1.00 12.00 18.00 17.00 16.00 13.00 Di 3.00 16.00 23.00 21.00 22.00 17.00 Ac 4.00 0.00 0.00 0.00 0.00 0.00 Mg# 0.27 32.69 47.13 45.62 44.92 37.49

Cl 775.00 435.00 149.00 136.00 27.00 229.00 S 77.00 142.00 70.00 84.00 292.00 87.00 V 0.00 147.00 212.00 192.00 191.00 192.00 Cr 6.00 158.00 545.00 498.00 482.00 255.00 Ni 3.00 75.00 228.00 219.00 199.00 105.00 Cu 6.00 58.00 80.00 75.00 76.00 59.00 Zn 139.00 86.00 82.00 92.00 89.00 80.00 Ga 30.00 17.00 17.00 19.00 18.00 20.00 Rb 214.00 39.00 28.00 35.00 32.00 40.00 Sr 94.00 573.00 397.00 386.00 388.00 663.00 Y 50.00 31.00 30.00 33.00 33.00 33.00 Zr 919.00 207.00 171.00 207.00 206.00 272.00 Nb 150.00 70.00 44.00 55.00 55.00 63.00 Ba 338.00 484.00 254.00 291.00 304.00 367.00 La 128.00 48.00 27.00 33.00 30.00 42.00 Ce 226.00 94.00 51.00 69.00 68.00 73.00 Nd 53.00 34.00 25.00 34.00 25.00 33.00 Pb 24.00 11.00 13.00 11.00 12.00 10.00 Th 55.00 7.00 4.00 5.00 4.00 5.00

139

SAMPLE TW92157 TW92159 TW92165 TW92169 TW92173 TW92175 LOCATION English rock English rock English rock English rock English rock Trabocco AGE 0.83 1.60 7.38 6.41 - 8.95 NAME (TAS) Basanite Basanite Alk. Basalt Tephrite Phonolite Phonolite

SiO 2 46.54 48.28 45.77 44.92 59.28 64.81

TiO 2 2.43 2.14 2.11 3.43 0.25 0.41

Al 2O3 16.49 16.55 15.12 16.39 19.35 14.37 FeO t 13.23 12.04 12.91 14.80 5.65 7.24 MnO 0.21 0.19 0.18 0.22 0.18 0.20 MgO 6.16 5.50 9.52 5.14 0.19 0.00 CaO 8.24 7.23 9.58 8.17 1.66 1.21

Na 2O 4.88 5.34 3.42 5.02 9.02 6.94

K2O 1.54 1.85 0.80 1.64 4.54 4.94

P2O5 0.74 0.75 0.40 0.85 0.05 0.02 LOI 0.64 0.44 0.03 0.67 0.18 0.01 TOTAL 99.80 99.42 99.86 99.91 100.36 100.14 Q 0.00 0.00 0.00 0.00 0.00 5.00 Or 9.00 11.00 5.00 10.00 26.00 29.00 Ab 25.00 31.00 23.00 24.00 45.00 49.00 Ne 11.00 10.00 5.00 13.00 19.00 0.00 Hy 0.00 0.00 0.00 0.00 0.00 5.00 Ol 13.00 12.00 19.00 10.00 1.00 0.00 Di 14.00 12.00 17.00 14.00 6.00 5.00 Ac 0.00 0.00 0.00 0.00 2.00 5.00 Mg# 31.77 31.36 42.44 25.78 3.25 0.00

Cl 436.00 399.00 248.00 371.00 1343.00 95.00 S 111.00 72.00 58.00 79.00 57.00 99.00 V 156.00 101.00 203.00 141.00 8.00 0.00 Cr 146.00 173.00 427.00 16.00 7.00 1.00 Ni 67.00 66.00 224.00 29.00 3.00 4.00 Cu 58.00 46.00 77.00 48.00 14.00 10.00 Zn 79.00 83.00 77.00 83.00 110.00 180.00 Ga 18.00 17.00 17.00 17.00 27.00 36.00 Rb 37.00 42.00 18.00 35.00 131.00 167.00 Sr 868.00 779.00 525.00 884.00 132.00 2.00 Y 32.00 32.00 25.00 38.00 54.00 55.00 Zr 264.00 298.00 147.00 232.00 658.00 737.00 Nb 63.00 67.00 34.00 73.00 164.00 132.00 Ba 438.00 411.00 249.00 472.00 1119.00 48.00 La 40.00 45.00 25.00 51.00 105.00 116.00 Ce 83.00 97.00 55.00 103.00 191.00 252.00 Nd 32.00 44.00 39.00 46.00 51.00 78.00 Pb 10.00 11.00 8.00 11.00 17.00 24.00 Th 5.00 8.00 0.00 6.00 23.00 30.00

140

SAMPLE TW92177 TW92178 TW92182 TW92184 TW92189 LOCATION Trabocco Wilch land Wilch land Lie cliff Lie cliff AGE - 8.55 8.52 - 8.45 NAME (TAS) Trachyte Trachyte Rhyolite Hawaiite Hawaiite

SiO 2 63.63 65.54 73.45 45.36 45.72

TiO 2 0.43 0.32 0.21 2.74 2.86

Al 2O3 14.34 15.18 11.86 15.94 15.75 FeO t 7.65 5.90 3.77 15.22 15.24 MnO 0.22 0.17 0.05 0.24 0.24 MgO 0.00 0.00 0.00 4.10 4.12 CaO 1.36 0.90 0.44 9.30 8.82

Na 2O 7.20 6.10 4.42 4.09 4.36

K2O 4.91 5.47 5.03 0.96 1.33

P2O5 0.03 0.02 0.00 0.39 0.50 LOI 0.32 0.21 0.79 1.51 1.17 TOTAL 100.10 99.81 100.01 99.86 100.10 Q 3.00 6.00 26.00 0.00 0.00 Or 29.00 32.00 30.00 6.00 8.00 Ab 49.00 51.00 36.00 28.00 28.00 Ne 0.00 0.00 0.00 6.00 8.00 Hy 5.00 3.00 2.00 0.00 0.00 Ol 0.00 0.00 0.00 5.00 5.00 Di 5.00 3.00 2.00 18.00 17.00 Ac 5.00 3.00 0.00 4.00 4.00 Mg# 0.00 0.00 0.00 21.22 21.28

Cl 184.00 2.00 2.00 122.00 288.00 S 61.00 49.00 58.00 202.00 81.00 V 0.00 5.00 9.00 240.00 233.00 Cr 1.00 2.00 7.00 2.00 0.00 Ni 3.00 3.00 5.00 13.00 13.00 Cu 5.00 8.00 2.00 33.00 42.00 Zn 177.00 132.00 202.00 104.00 99.00 Ga 33.00 31.00 36.00 21.00 21.00 Rb 146.00 135.00 276.00 25.00 32.00 Sr 3.00 21.00 1.00 617.00 569.00 Y 76.00 65.00 126.00 30.00 32.00 Zr 553.00 419.00 779.00 171.00 196.00 Nb 115.00 96.00 172.00 43.00 53.00 Ba 82.00 358.00 15.00 319.00 389.00 La 98.00 96.00 184.00 27.00 34.00 Ce 239.00 195.00 385.00 60.00 79.00 Nd 78.00 61.00 128.00 20.00 39.00 Pb 21.00 12.00 56.00 10.00 10.00 Th 19.00 16.00 38.00 4.00 5.00

Samples were analysed by XRF for major elements and for S, V, Cr and Ni (Wilch, 1997). Trace elements were analyzed by ICP-MS. Wt% normative analyses are Q- quartz, Or - orthoclase, Ab -albite, Ne - nepheline, Hy -hypersthene, Ol -olivine, Di -diopside, Ac -acmite. 141

Mg# (Mg number) defines the value for (MgO/(MgO+FeO))*100. Rock names are given according to the TAS (Total Alkali vs Silica) plot, after Le Bas et al., 1986. Age data are in unit of Ma (million of years), deteremined by the 40 Ar/ 39 Ar method (Wilch, 1997).