silts tone/mudstone and interbedded fine-grained sandstone. extensive flood plain. Sheet sandstones represent major cre- Internally, the coarser sandstone units consist of scour-bound- vasse splays. The proportion of sandstone to siltstone/ ed cosets of 0.2- to 0.5-meter thick trough cross-beds. In some mudstone is an indication of the proximity of the section to a cases, thin siltstone drapes have preserved original dune geom- major channel. The thick sandstones of the upper member etry. Horizontal trails and vertical burrows occur along these recorded a large increase in the amount of sand-sized volcanic surfaces and penetrate downward through crossbeds. The detritus in the drainage system, producing an extensive braid greenish gray siltstone/mudstone units typically contain root plain. structures and locally preserve dark gray organic matter, sug- We wish to express appreciation to fellow scientists, es- gesting that they were originally carbonaceous. pecially David Elliot and John Splettstoesser, and the support Sandstones in the Fremouw contain an increasing proportion crew at the Beardmore South camp. We particularly thank mem- of volcanic detritus upward in the section. The proportion of bers of th Vanderbilt University group led by Molly Miller and sandstone to siltstone/mudstone diminishes in the middle Julia Miller, the Augustana College/Wayne State University member. At some localities the middle member is predomi- group led by Bill Hammer, and the Ohio State University group nantly fine grained; in others, it is very sandy. The upper led by Tom Taylor, with whom we worked side by side. member is predominantly trough cross-bedded, medium- This research was supported by National Science Foundation grained volcaniclastic sandstone with some greenish gray or grant DPP 84-18354. dark gray carbonaceous siltstone/mudstone interbeds. The overlying Triassic Falla Formation, a coarse-grained, quartzose sandstone, is channeled deeply into the Fremouw Formation. Vertebrate and plant fossils are locally abundant in the Fre- mouw Formation. Vertebrate fossils occur in the lower member References and in the lower part of the upper member (see Hammer et al., Antarctic Journal, this issue). They are most abundant at the tops Barrett, P.J. 1969. Stratigraphy and petrology of the mainly fluviatile of channel-form sandstone units. Silicified plant fossils, includ- Permian and Triassic Beacon rocks, Beardmore Glacier area, Ant- arctica. Institute of Polar Studies Report, 34. ing blocks of peat, large logs, and in situ stumps, occur in the Barrett, P.J. 1970. Paleocurrent analysis of the mainly fluviatile Permian upper part of the upper member (See Taylor, Smoot, and Collin- and Triassic Beacon rocks, Beardmore Glacier area, Antarctica. Journal son, Antarctic Journal, this issue). of Sedimentary Petrology, 40(1), 395-411. The basal Fremouw sandstones are interpreted as sandy Hammer, W.H., S.L. DeFauw, W.J. Ryan, and J.T. Tamplin. 1986. New braided stream deposits that filled topographic relief on the vertebrates from the Fremouw Formation (Triassic), Beardmore Permian-Triassic unconformity. Paleocurrent data gathered this Glacier region, Antarctica. Antarctic Journal of the U.S., 21(5). past field season do not support the approximately 180° reversal Miller, ME, and R.S. Frisch. 1986. Depositional setting of the (Permian) in paleoslope from Permian to Triassic suggested by Barrett Mackellar Formation, Beardmore Glacier area. Antarctic Journal of the (1969, 1970). The northward swing in paleocurrent dispersal U. S., 21(5). Taylor, T. N., E. L. Smoot, and J. W. Collinson. 1986. Paleoenvironmentof that began with the deposition of the upper part of the Buckley Upper Triassic plants from the Fremouw Formation. Antarctic Journal Formation apparently continued into the Triassic (figure). Tri- of the U. S., 21(5). assic dispersal directions were predominantly northward. Vavra, C.L. 1984. Provenance and alteration of the Triassic Fremouw The lower and middle members of the Fremouw were deposi- and Falla formations, central Transantarctic Mountains, Antarctica. ted by low sinuosity braided to anastomosing streams, on an Institute of Polar Studies Report, 87,

these are the Pagoda, Mackellar, Fairchild, and Buckley Forma- Sedimentology of fine-grained tions. These units were deposited in a range of environments Permian clastics, but generally record a transition from a glaciated basin, through the infilling of a post-glacial basin, to a fluvially dominated central Transantarctic terrestrial realm. The general nature of this sequence was de- Mountains scribed by Barrett (1969) and Lindsay (1969), but the entire sequence was examined in more detail during the 1985-1986 field season by a nine-person field team from Vanderbilt Uni- L.A. KRISSEK and T.C. HoRNEI versity (see Miller and Waugh, Antarctic Journal, this issue; Mil- ler and Frisch, Antarctic Journal, this issue) and Ohio State Uni- Institute of Polar Studies versity (see Collinson and Isbell, Antarctic Journal, this issue). and The objective of this paper is to outline briefly the results of our Department of Geology and Mineralogy field work and to describe the directions of our continuing Ohio State University laboratory investigations. Our future work will complement the Columbus, Ohio 43210 efforts of our colleagues, who are examining each unit within the Permian sequence. While operating out of the Beardmore South remote camp for In the central Transantarctic Mountains, the Permian se- approximately 2 months, we measured 24 sections at 21 lo- quence is composed of four formations. In ascending order, calities. These sections totalled 3,789 meters in thickness and

30 ANTARCTIC JOURNAL provide a good stratigraphic and geographic distribution of data Locations of stratigraphic sections measured in the across the northern portion of this Permian basin. The sample Beardmore Glacier area, and stratigraphic units locations are shown in the figure, and a key to the sample considered at each locality locations is given in the table. Of these 24 sections, 9 included Pagoda strata, 13 included Mackellar rocks, 9 included Fairchild Abbreviation Place name Formations measured interval, and 13 included the Buckley sequence. The 312 sam- ples collected from these sections were distributed as follows: 48 from the Pagoda, 106 from the Mackellar, 21 from the Fair- WG Wahl Glacier Buckley child, and 138 from the Buckley. As a result of this field effort, TGA Tillite Glacier Pagoda, Mackellar we will be able to address several objectives. TGF Tillite Glacier Mackellar, Fairchild Several approaches are necessary to study the sedimentology MMD Helm Glacier Mackellar, Fairchild, Buckley MMC Mount Weeks of fine-grained clastic rocks (shales and siltstones). Although Pagoda, Mackellar MMQ Moore Mountains Mackellar field relations are important, a detailed laboratory analysis is MMP Moore Mountains Pagoda generally necessary to extract important data about their sedi- MMA Moore Mountains Mackellar, Fairchild mentologic history. The objective of our continuing efforts is to MB Mount Bowers Mackellar, Fairchild, Buckley use geochemical and mineralogic data from these siltstones and MA4 Mount Achernar Upper Buckley shales to decipher the record of paleogeography, provenance, MA5 Mount Achernar Middle Buckley and paleoclimate in the Permian sequence of the central Trans- MA6 Mount Achernar Lower Buckley antarctic Mountains. LP Lamping Peak Buckley This work will be closely coordinated with on-going efforts of MD Mount Deakin Mackellar, Fairchild the other members of the Vanderbilt/Ohio State group. For MP Mount Picciotto Buckley TR Turnabout Ridge Pagoda, Mackellar, Fairchild example, the Pagoda Formation, which is composed of MK Mount Korsch Mackellar, Fairchild glaciomarine and glacial deposits (Lindsay 1969), is being exam- CP Clarkson Peak Pagoda, Mackellar, Fairchild MMZ Mount Miller Pagoda, Mackellar MR Mount Ropar Buckley Cl Cherry Icefall Pagoda, Mackellar MX med in detail by Miller and Waugh (Antarctic Journal, this issue). We will use the mineralogy and geochemical of fine-grained diamictites and rare black shales to evaluate sources (Fan 1976; Keller 1970) and weathering characteristics (Nesbitt and Young 1982) of the Pagoda sediments. These data may provide clues to E& the types of rocks removed from atop the Devonian Alexandra Formation during Permian glaciation. The Mackellar Formation was deposited in a basin that may be analogous to the Karoo Basin of South Africa, thereby raising several questions about the depositional environments of the Mackellar shales and siltstones. In conjunction with Miller and Frisch (Antarctic Journal, this issue), we are attempting to deter- TG A mine if the Mackellar basin represents a closed basin, as sug- TOF gested by Lindsay (1969) or if local oxygen variations influenced deposition along an oceanic continental margin. Paleosalinity determinations (Cody 1971; Berner and Raiswell 1984), trace fossil diversity (Miller 1984), mineralogic data (Edzwald and OMelia 1975), and field relations are all being brought to bear on the problem. In addition, the mineralogical and geochemical

tA record of the glacial-postglacial transition in this interval is under investigation. The Fairchild and Buckley Formations were deposited in fluvial environments and include overbank siltstones and shal- es. The Buckley Formation also contains autochthorious and 0 50 allochthonous coals. While Collinson and Isbell examine the facies architecture and petrology of the fluvial sediments (Ant- arctic Journal, this issue), we are concentrating on the record of sediment provenance and paleoclimate in the overbank - deposits. Our progress to date has seen the completion of the field study and sample collection. Initial laboratory results suggest some alteration by Jurassic intrusions, but the bulk of the labo- ratory data is still forthcoming. We anticipate that the Permian paleogeography, paleoclimatology, and provenance of the cen- Geographic distribution of measured sections, Beardmore Glacier tral Transantarctjc Mountains will be well constrained within area. See table for further information about individual localities. the next year.

1986 REVIEW 31 We wish to express our sincere appreciation to the other Edzwald, J.K., and C.R. OMelia. 1975. Clay distributions in recent members of the Vanderbilt/Ohio State University research estuarine sediments. Clays and Clay Mineralogy, 23, 39-44. team, our fellow scientists from the Beardmore South camp, Fan, P.F. 1976. Recent silts of the Santa Clara River drainage basin, and the civilian and military support personnel for their efforts southern California: A mineralogical investigation of their origin and on our behalf. evolution. Journal of Sedimentary Petrology, 46, 802-812. This work is supported by National Science Foundation grant Keller, W.D. 1970. Environmental aspects of clay minerals. Journal of Sedimentary Petrology. 40, 788-813. DPP 84-18354. Lindsay, J.F. 1969. Stratigraphy and sedimentation of lower Beacon References rocks in the central Transantarctic Mountains. Institute of Polar Studies Report, Vol. 33. Columbus: Ohio State University Press. Miller, M.F. 1984. Distribution of biogenic structures in Paleozoic non- Barrett, P.J. 1969. Stratigraphy and petrology of the mainly fluviatile marine and marine margin sequences: An actualistic model. Journal of Permian and Triassic Beacon rocks, Beardmore Glacier area, Ant- Paleontology, 58, 550-570. arctica. institute of Polar Studies Report, Vol. 34. Columbus: Ohio State Miller, M.F., and R.S. Frisch. 1986. Depositional setting of the (Permian) University Press. Mackellar Formation, Beardmore Glacier area. Antarctic Journal of the Berner, R.A., and R. Raiswell. 1984. C/S method for distinguishing U. S., 21(5). freshwater from marine sedimentary rocks. Geology, 12, 365-368. Miller, J.M.G., and B.J. Waugh. 1986. Sedimentology of the Pagoda Cody, R.D. 1971. Adsorption and the reliability of trace elements as Formation (Permian), Beardmore Glacier area. Antarctic Journal of the environment indicators for shales. Journal of Sedimentary Petrology, 41, U. S., 21(5). 461-471. Nesbitt, H.W., and G.M. Young. 1982. Early Proterozoic climates and Collinson, J.W., and J.L. Isbell. 1986. Permian-Triassic sedimentology of plate motions inferred from major element chemistry of lutites. the Beardmore Glacier region. Antarctic Journal of the U.S., 21(5). Nature, 299, 715-717.

first at ito 5 meters deep and 20 to 30 meters apart. These forms Sirius Formation basal contacts in the probably represent glacial whaleback features. Overall, the plat- Beardmore Glacier region form dips approximately 2° to the northwest. Where naturally exposed, it is weathered, in places into small, irregularly shaped tors up to 40 centimeters high and 25 centimeters across. Re- moval of the overlying compacted diamictite reveals a fresh, M.C.G. MABIN heavily striated surface. Striation directions measured at six localities along the eastern side of the platform trended between Institute of Polar Studies 22° and 105°, with the predominant ice-flow direction being to Ohio State University the east-northeast, as reported by McKelvey et al. (1984) and Columbus, Ohio 43210 Mercer (1972). On the western side of the platform, striations are similarly oriented, and there are crescentic gouges up to 35 centimeters across, convex in an east-northeast direction (Har- wood personal communication). Also exposed on this western Sirius Formation outcrops examined in the Beardmore Glacier edge is a P-form feature 2 meters across and 0.5 meter deep, region during the 1985-1986 season are described by Webb et al. eroded into the dolerite (Harwood personal communication). (in preparation). The disconformity between the basal Sirius This meandering channel is exposed for 5 meters and is ori- Formation and underlying rocks was examined at five localities. ented southeastward. It indicates the presence of subglacial The morphology of the underlying surface exhibits varying meltwater beneath the ice that overrode the platform. degrees of ice moulding on a variety of rock types, as reported Sirius Formation deposits are well exposed in the Dominion from other sites (Mayewski and Goldthwait 1985). It is referred Range in cliffs on the east side of the Beardmore Glacier, be- to by Webb et al. (Antarctic Journal, this issue; in preparation) as tween 2.2 and 3.9 kilometers southwest of Plunket Point the "Dominion erosion surface." At two locations, Mount Sirius (85°06S 166°56E) (Oliver 1964; Mercer 1972). The diamictite and Plunket Point, it is extensively exposed and easily accessi- rests on an undulating surface of columnar-jointed dolerite at ble. Surveys of the contact were made using a theodolite and about 1,750 meters above sea level and 15 to 95 meters above the electronic distance meter. glacier. The undulations vary from 3 to 36 meters high and 80 to At the type locality, Mount Sirius (84°08S 163°15E), 85 300 meters apart and are interpreted as whaleback features. meters of diamictite rest on a platform of columnar jointed Striations on the dolerite trend between 355° and 25°, the varia- dolerite, which is approximately 2,200 meters above sea level tions representing diverging and converging or north-north- and 400 meters above the surrounding Bowden Névé. In plan east flowing ice over and around the whalebacks. Other glacial view, the platform is L-shaped, one limb extending north for 1.3 erosion features include minor plucking on the downglacier kilometers, the other east for 0.9 kilometer. Width varies from (northern) sides of the whalebacks, lunate fractures up to 8 125 to 500 meters, and it covers an area of 4 hectares. The centimeters across, and small grooves. A fault has displaced platform edge varies between 2,179 and 2,226 meters above sea both the dolerite and overlying Sirius Formation diamictite. The level. It has two sets of undulations: one set is 20 meters deep northern side is upthrown 55 meters, and the fault trace can be and 300 meters apart, and the other set is superimposed on the followed south for 2.1 kilometers.

32 ANTARCTIC JOURNAL