This research was supported in part by National Science palynomorphs from the Buckley Formation on Mount Achernar, Foundation grant DPP 86-11884. The specimens were collected Antarctica. Grana.. by James W. Collinson, John L. Isbell, and the late James M. Kemp, E. 1974. Permian flora from the Beaver Lake area. 1. Palynol- ogical examination of samples. Bureau of Mineral Resources, Geology Schopf of the Byrd Polar Research Center. and Geophysics, Australia Bulletin, 126, 7-12. Kyle, R.A. 1976. Palaeobotanical studies of the Permian and Triassic Victoria Group (Beacon Supergroup) Gf South Victoria Land, Ant- arctica. (Unpublished doctoral dissertation, University of Welling- References ton, New Zealand.) Kyle, R.A. 1977. Palynostratigraphy of the Victoria Group of South Balme, BE., and C. Playford. 1967. Late Permian plant microsossils Victoria Land, Antarctica. New Zealand Journal of Geology and Geo- from the Prince Charles Mountains, Antarctica, Revue de Micropa- physics, 20, 1081-1102. leontologie, 10, 179-192. Kyle, R.A., and J.M. Schopf. 1977. Palynomorph preservation in the Barrett, P.J., D.H. Elliot, and P.J. Lindsay. 1986. The Beacon Super- Beacon Supergroup of the Transantarctic Mountains. Antarctic Jour- group (Devonian-Triassic) and Ferrar Group (Jurassic) in the Beard- nal of the U.S., 12(5), 121-122. more Glacier area, Antarctica. In M.D. Turner and J.F. Splettstoesser Kyle, R.A., and J.M. Schopf. 1982. Permian and Triassic palynostra- (Eds.), Geology of the central Transantarctic Mountains. (Antarctic Re- tigraphy of the Victoria Group, Transantarctic Mountains. In Pro- search Series, Vol. 36.) Washington, D.C.: American Geophysical ceedings of the 3rd Symposium on Antarctic Geology and Geophysics, Madison, Union. Wisconsin, 1977. Dibner, A.F. 1978. Palynocomplexes and age of the Amery Formation Tasch, P. 1978. Permian palynomorphs (Coalsack Bluff, Mount Sirius, deposits, East Antarctica. Pollen et Spores, 20, 504-422. Mount Picciotto) and other studies. Antarctic Journal of the U.S., 13(5), Farabee, M.J., E.L. Taylor, and T.N. Taylor. In press. Upper Permian 19-20.

also mapped post-Permian normal faults that confirm sub- Aspects of the late Proterozoic stantial extensional deformation in the central Transantarctic and Paleozoic geology Mountains, and we collected carbonaceous and silicified plant fossils from a new locality (N-87-2; figure, block D) in sand- of the Churchill Mountains, stones of the Beacon Supergroup. southern Victoria Land Our field team consisted of Margaret N. Rees, Albert J. Row- ell, and two field assistants, Sarah Jones and Peter Braddock. We were put into our first field area (figure, block C) by an MARGARET N. REES LC-130 ski-equipped Hercules airplane on the Nicholson Pen- insula (80°42S 159°22E) on 23 November 1987 and picked up Department of Geoscience there on 16 December. The put-in at our second field area University of Nevada at Las Vegas (figure, bock D), the Starshot Glacier (81°54S 158°29E), was Las Vegas, Nevada 89154 on 18 December, and we were pulled out on 6 January. Al- though much was accomplished at localities M, N, and 0 ALBERT J. ROWELL (figure, block D), numerous days of poor visibility resulted in only 1 day at locality P to examine the Starshot Formation, and Department of Geology consequently, the relationships there are still unresolved. University of Kansas Four formations have been referred to the Byrd Group: Lawrence, Kansas 66045 Shackleton Limestone, Dick Formation, Douglas Conglomer- ate, and Starshot Formation (reviewed in Laird 1981). The Lower ERIN D. COLE Cambrian Shackleton Limestone throughout the Churchill Mountains represents only shallow-water carbonate shelf and peritidal deposits (Rees, Rowell, and Pratt 1987; Rees, Pratt, Department of Geoscience University of Nevada at Las Vegas and Rowell in press). The limestone breccia sequence at Crack- Las Vegas, Nevada 89154 ling Cwm (figure, block C), which tentatively was interpreted as a deep-water deposit in the Shackleton by Burgess and Lammerink (1979), we consider to be a younger, very proximal Stratigraphic and structural data collected during our 1987- alluvial fan accumulation. It is fractured, deformed, and faulted 1988 field season in the Churchill Mountains (figure) together against a highly cleaved and isoclinally folded argillite, which with isotopic and geochemical data necessitate a revision in in turn is juxtaposed to deformed Shackleton. The breccia is the stratigraphy of the pre-Devonian Paleozoic Byrd Group clast supported, matrix poor, and extremely poorly sorted with and a reinterpretation of the regional geological history. We clasts ranging from 0.5 centimeters to 10 meters. Most clasts conclude that there is no evidence for deep-water deposition are dark gray mottled or white fenestral limestones; cyano- in the Shackleton Limestone, that the Dick Formation is part bacteria-archaeocyathan boundstone clasts are very rare. Bed- of the basin-fill phase of sedimentation formed subsequent to ding within large blocks is obvious, but within the breccia the initial episode of Paleozoic deformation, and that there is sequence it can be traced laterally only a few meters. No fine- no evidence for volcanic activity in the area during deposition grained, marine basin or slope interbeds nor clasts derived of the group. Although not the focus of our field work, we from such occur in the sequence. This breccia sequence may

1988 REVIEW 23 159 160

V V Z% J7 +1

crac kling J - A%

0 5 165 -- 17 —J Km

Mt I co Fig I/ Dick— \ L NP be - 7( Ross / N Ice Shelf

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Location of the two field areas between the Byrd and Nimrod glaciers in the central Transantarctic Mountains. The bold letters and numbers In 1C and 10 are localities visited during the 1987-1988 field season and are discussed in the text. The geology illustrated in C and D is generalized to show only outcrop distribution and major faults. The multiple phases of folding are not shown or implied. In C, outlines of nunataks A through F are approximated In part from pace-and-compass maps and oblique air photographs. Their scale bars equal ap- proximately 100 meters. In D, the geology is modified from Laird, Mansergh, and Chappell (1971).

be correlative, at least in part, with the Douglas Conglomerate, C) interpreted as braid-plain deposits, is typically a massive, which elsewhere in the Churchill Mountains is of similar lith- crudely planar-, or trough-cross-stratified pebble-to-cobble ology (Rees and Rowell in press). conglomerate with thin interbedded cross-stratified and rip- The Douglas Conglomerate at locality M (figure, block D) pled sandstone. It is composed predominantly of limestone, unconformably overlies highly deformed Shackleton Lime- dolomite, and sandstone clasts with lesser amounts of mafic stone (Rees, Rowell, and Pratt 1987; Rowell et al. in press); volcanic and granitic clasts that collectively represent a recycled however, at its type locality (Locality B, figure, block C; Skinner orogen provenance (sensu Dickinson and Suczek 1979). 1964, 1965), it gradationally overlies the fine-grained Dick For- We interpret the Dick Formation to represent fine-grained mation. The Douglas at localities A, B, C, and I (figure, block fluvial to marginal marine deposits and to be genetically related

24 ANTARCTIC JOURNAL to the Douglas not the Shackleton. The Dick at its type locality This study has been supported by National Science Foundation (Locality B, figure, block C; Skinner 1964, 1965) is composed grants DPP 85-18157 and DPP 87-44459 to the University of of rippled and cross-bedded sandstones; abundant parallel- Nevada, Las Vegas, and DPP 85-19722 to the University of bedded shales with rare mudcracks and rare horizontal traces; Kansas. rippled siltstones; and, near its top, thin conglomerate beds. References Its style and sequence of deformation is similar to that recorded in the Douglas near Mount Hamilton (Rees et al. in press). Burgess, C.J., and W. Lammerink. 1979. Geology of the Shackleton The Dick at locality E (figure, block C) is tectonically juxtaposed Limestone (Cambrian) in the Byrd Glacier area. New Zealand Antarctic to the Shackleton Limestone along a folded, sheared, and prob- Record, 2, 12-16. ably faulted contact. At that locality, thin polymictic limestone Dickinson, W.R., and C. A. Suczek. 1979. Plate tectonics and sandstone conglomerates with compositions similar to those in the Doug- composition. American Association of Petroleum Geologists Bulletin, 63, las are interbedded with the Dick. These carbonate-rich beds 2164-2182. are depositionally unrelated to the Shackleton. Laird, M.G. 1981. Lower Palaeozoic rocks of Antarctica. In C.H. Hol- land (Ed.), Lower Paleozoic of the Middle East, Eastern and Southern Snow bounded outcrops of volcanics at localities 17 and J Africa, and Antarctica. New York: John Wiley and Sons Ltd. (figure, block C), initially included in the Dick Formation (Skin- Laird, M. G., G. D. Mansergh, and J.M.A. Chappell. 1971. Geology of ner 1964, 1965), are pillow basalts that have a minimum age the central Nimrod Glacier area, Antarctica. New Zealand Journal of of 586 ± 20 million years based on potasium/argon dates. As Geology and Geophysics, 14, 427-468. such, they are not related to the Byrd Group. Major, trace, Rees, MN., G.H. Girty, S.K. Panttaja, and P. Braddock. 1987. Multiple and rare-earth elemental data suggest that the basalts were phases of early Paleozoic deformation in the central Transantarctic generated by partial melting of mantle slightly enriched in light Mountains. Antarctic Journal of the U.S., 22(5), 33-35. rare-earth elements and indicate that they erupted either in an Rees, MN., A.J. Rowell, and B.R. Pratt. 1987. The Byrd Group of the oceanic or continental within-plate tectonic setting. Holyoake Range, central Transantarctic Mountains. Antarctic Journal The Byrd Group and unconformably overlying Beacon Su- of the U. S., 19(5), 3-5. Rees, M.N., B.R. Pratt, and A.J. Rowell. In press. Early Cambrian pergroup are displaced along normal faults indicated on the reefs, reef complexes, and associated lithofacies of the Shackleton figure, block D. At locality M, the exact orientation or position Limestone, Transantarctic Mountains. Sedimen tology. of the fault which lies in deformed Shackleton is not known, Rees, M.N., and A.J. Rowell. In press. The pre-Devonian Paleozoic but it displaces the Kukri unconformity down to the north clastics of the central Transantarctic Mountains: Stratigraphy and approximately 300 meters. The northern fault at locality 0 depositional settings. Proceedings of the Fifth International Symposium juxtaposes outcrops of Douglas Conglomerate and Permian on Antarctic Earth Sciences. sandstones along a nearly vertical surface striking north 65°E Rowell, A.J., M.N. Rees, R.A. Cooper, and B.R. Pratt. In press. Early with northwest downthrow of approximately 500 meters. The Paleozoic History of the central Transantarctic Mountains: Evidence third fault, viewed only from a distance, trends northward from the Holyoake Range, Antarctica. New Zealand Journal of Geology with down to the east displacement of approximately the same and Geophysics. magnitude. Skinner, D.N.B. 1964. A summary of the geology of the region between Byrd and Starshot glaciers, south Victoria Land. In R.J. Adie (Ed.), We are grateful to Gary Girty and Daniel Krummenacher at Antarctic geology. Amsterdam: North Holland. San Diego State University for the tentative potassium/argon Skinner, D.N.B. 1965. Petrographic criteria of the rock units between age dates. Plant fossils have been sent to Thomas and Edith the Byrd and Starshot glaciers, south Victoria Land, Antarctica. New Taylor at the Department of Botany, Ohio State University. Zealand Journal of Geology and Geophysics, 8, 292-303.

Geochemistry of Paleozoic granites Our original aims were to elucidate the petrogenesis of the Early Paleozoic granitic basement of the Transantarctic Moun- of the Transantarctic Mountains tains, and to use geographic variations of chemical and isotopic compositions of the granites to infer the pre-Paleozoic crustal structure and tectonic development of the region. Our expec- SCOTT G. BORG, DONALD J. DEPAOLO, and BRIAN M. SMITH tations for this work are being exceptionally well realized. We have discovered clear isotopic patterns that are leading to a Berkeley Center for Isotope Geochemistry comprehensive and unprecedented picture of the crustal struc- Department of Geology and Geophysics ture and tectonics of the region, and its relation to the east University of California antarctic shield and the other parts of Gondwanaland. and Full samarium-neodymium and rubidium-strontium iso- Earth Science Division Lawrence Berkeley Laboratory topic and concentration measurements have been completed Berkeley, California 94720 on 23 granites and 6 samples of metamorphic rocks. Another 10 samples of metamorphic rocks are in the analytical cycle. Isotopic analyses of mineral separates from three of the sam- Work during the last year (1987-1988) of this continuing ples were completed to check equilibration ages. Oxygen iso- project has been devoted mainly to analytical work on granites topic analyses have been completed on quartz separates from and metamorphic country rocks collected during the two pre- the granites and on whole-rock splits from the metamorphic vious field seasons in Antarctica (Borg et al. 1986, 1987). rocks and non-quartz-bearing intrusive rocks. Uranium-lead

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