conducted with finesse by Mrs. Nova Young and Miss at Gaussberg, at Mirnyy, and sporadically in the Camas Lott, working under National Science Founda- Transantarctic Mountains from Cape Adare south tion grant GV-25341. Thanks to their efforts, numer- to Mount Early in the Scott Glacier area. A detailed ous excellent fossils have been extracted from the study of the geochemistry of the volcanics of Victoria enclosing matrix. Land is in progress. The major, minor, and trace Concurrent with this work Miss Pamela Lunge has elements, including the lanthanides, are being de- been making truly beautiful line drawings of the termined on an extensive suite of these rocks. Analy- fossils. In a majority of cases pen and ink drawings ses of the isotopic composition of strontium, expressed provide the most satisfactory illustrations of fossil as the ratio of strontium-87 to strontium-86, are near- vertebrates. ing completion, and the current results are given in Thus the gound work has been largely accomp- the table. Some samples from the southern Trans- lished, antecedent to the detailed studies of the fossils. antarctic Mountains and from West Antarctica are Such studies will be carried on during the months to of special interest and have been included in the come. study. Already it is apparent that the Lower Triassic tetrapods of Antarctica have remarkably close re- The average 87Sr/86Sr ratio for 45 analyzed samples semblances to fossils from the Middle Beaufort beds from Victoria Land is 0.7038 ± 0.0002 (1—). This of South Africa, a point that has been made (but on value is similar to that of basaltic rocks from oceanic less detailed evidence) in previous contributions to areas (compiled by Gast, 1967). In addition, the this journal. For example, it seems quite evident that isotope composition of strontium is similar to the there are two species of Lystrosaurus in the Fremouw 875r/86Sr ratios measured for volcanic rocks from Formation, which may be equated with two of the Deception Island by Faure characteristic South African species. et al. (1971). The two samples of basalt from Mount Early have slightly Other taxonomic identities are obvious—some at higher 87 86Sr ratios, 0.7058 and 0.7063, but there the species level, others more probably at the generic Sr/ is chemical and mineralogical evidence that these stage. And it appears that some fossils may represent new genera. samples might have been contaminated, probably during emplacement. The volcanics from West Thus the fossils from the Fremouw Formation Antarctica also have 87Sr/86 represent in essence the well-known Sr ratios characteristic of Lystrosaurus oceanic basalts, with the exception of sample 17e ` fauna of South Africa, but with some differences which has a value of 0.7141. The concentrations of among certain constituents of the antarctic assem- strontium and rubidium for this sample are 5.58 and blage. The significance of a Lystrosaurus fauna in 106.6 parts per million, respectively. Assuming that Antarctica, as an indication of a close ligation be- this volcanic is 10 million years old, then the "initial" tween Antarctica and southern Africa at the begin- 87 Sr/ 86Sr ratio would be 0.7045. If this assumed age ing of Triassic time, is obvious. The point need not is of the correct order of magnitude, the high ru- be labored at this place. It nicely illustrates the im- bidium/strontium ratio could account for the high portance of the distributions of extinct land-living present-day 87Sr/86Sr ratio. vertebrates for the perfection of our knowledge con- cerning past continental relationships. Special thanks are due to G. Faure for his con- tinued encouragement during the course of this ex- tensive study. Miss Terry Tickhill, Mrs. Eileen Mc- Saveney, and Mrs. Kay Lindsay assisted one author (LMJ) in the collection of samples during the 1969- 1970 austral summer. Additional samples were gen- Geochemistry of the McMurdo erously provided by G. H. Denton, H. H. Gair, J. volcanics, Victoria Land Kovach, W. E. LeMasurier, V. H. Minshew, Miss Part I. Strontium isotope composition T. Sledzinska, and S. B. Treves. The mass spectro- metric analyses were made at the Laboratory for Lois M. JONES Geochemistry and Isotope Geology, Department of Department of Geology Geology, The Ohio State University, or in the Analy- University of Georgia tical Chemistry Division of the Oak Ridge National RAYMOND L. WALKER Laboratory, which is operated for the U. S. Atomic Oak Ridge National Laboratory Energy Commission by Union Carbide Corporation. Financial assistance through National Science Foun- The McMurdo volcanics are basic rocks of late dation grants GA-14427, GA-14573 , and GA-898X Tertiary-Quaternary age that occur on Ross Island, is gratefully acknowledged. 142 ANTARCTIC JOURNAL Strontium isotope composition of the McMurdo volcanics from Victoria Land and selected volcanics from the southern Transantarctic Mountains and West Antarctica. Sample Rock type - Location 86Sr/88Sr 87Sr/86Sra Southern Victoria Land 272 olivine basalt Cape Bird 0.1183 0.7045 281 hornblende andesite Cape Bird 0.1176 0.7044 273 olivine basalt Cape Crozier 0.1180 0.7045 277 tuff Turks Head 0.1179 0.7028 282 trachyte Observation Hill 0.1172 0.7032 257 trachyte Observation Hill 0.1187 0.7045 258 olivine basalt Post Office Hill 0.1190 0.7040 259 kenyte Cape Royds 0.1185 0.7042 287 kenyte Cape Royds 0.1171 0.7044 LJ-183 kenyte Cape Royds 0.1225 0.7020 LJ-171 (volcanic) Cape Barne 0.1210 0.7044 LJ-179 kenyte Cape Barne 0.1238 0.7033 LJ-172 kenyte Cape Evans 0.1219 0.7025 LJ-173 kenyte Cape Evans 0.1224 0.7027 LJ-174 kenyte Cape Evans 0.1197 0.7028 LJ-175 kenyte Cape Evans 0.1195 0.7027 LJ-180 kenyte Cape Evans 0.1208 0.7025 LJ-181 kenyte Cape Evans 0.1210 0.7040 275 olivine basalt Dailey Islands 0.1183 0.7047 288 kenyte Inaccessible Island 0.1177 0.7047 21001 (volcanic) Brown Peninsula 0.1181 0.7036 21058 (volcanic) Brown Peninsula 0.1188 0.7041 21248 (volcanic) Black Island 0.1190 0.7037 262 olivine basalt Wright Valley 0.1188 0.7043 66-106 basalt Wright Valley 0.1192 0.7035 66-182A basalt Wright Valley 0.1186 0.7042 LJ-184 olivine basalt Wright Valley 0.1199 0.7038 LJ-185 olivine basalt Wright Valley 0.1210 0.7033 66-170A basalt Taylor Valley 0.1186 0.7035 66-170B basalt Taylor Valley 0.1188 0.7047 327 basalt Taylor Valley 0.1192 0.7048 343 basalt Taylor Valley 0.1184 0.7038 344 basalt Taylor Valley 0.1176 0.7035 346 basalt Taylor Valley 0.1175 0.7039 341 basalt Mount Dromedary 0.1180 0.7032 342 basalt Howchin Glacier 0.1177 0.7033 LJ-176 kenyte Garwood Valleyb 0.1218 0.7030 LJ-182 kenyte Garwood Valleyb 0.1209 0.7022 Northern Victoria Land 268 basalt Cape Hallett 0.1173 0.7037 269 basalt Cape Hallett 0.1191 0.7042 270 basalt Cape Hallett 0.1183 0.7054 301 basalt Mount Overlord 0.1195 0.7044 302 (volcanic) Mount Overlord 0.1183 0.7047 304 (volcanic) Campbell Glacier 0.1186 0.7034 305 (volcanic) Campbell Glacier 0.1194 0.7041 Southern Transantarctic Mountains 0.1193 0.7042 271 basalt Mount Wyattb 0.1180 0.7050 295 basalt Paradox Ridge 0.1190 0.7058 317 olivine basalt Mount Early 262 olivine basalt Mount Early 0.1182 0.7063 West Antarctica 0.1197 0.7141 17e (volcanic) Mount Hampton 0.1181 0.7037 19b kenyte Mount Hampton 26A basalt Mount Cumming 0.1187 0.7032 0.1186 0.7039 326 kenyte Doumani Peak 52A kenyte Mount Sidley 0.1183 0.7033 0.7031 56b basalt Mount Aldez 0.1180 71A kenyte Mount Frakes 0.1190 0.7035 allormalized to 86Sr/88Sr = 0.1194. bMorajne September-October 1972 143 References 6. There were widespread intrusions of granitic Faure, G., C. H. Shultz, and R. H. Carwile. 1971. Isotope plutons during the entire Cretaceous period with composition of strontium in volcanic rocks from Deception activity at a maximum in mid-Cretaceous time. These Island. Antarctic Journal of the U.S., VI(5): 197-198. plutons are exposed in Edward VII Peninsula, Ford Gast, P. W. 1967. Isotope geochemistry of volcanic rocks. In: Basaltc: the Poldervaart Treatise on Rocks of Basaltic Ranges, Kohler Mountains, and Bear Island. New Composition, Vol. 1. New York, Interscience Publishers, potassium-argon age determinations that supplement 325-358. those already published (Boudette et al., 1966; Wade, 1969; Halpern, 1968, in press) are listed in the table. 7. The Cenozoic period is characterized by periodic eruptions of alkali basalt and pyroclastics. This vol- canic activity has continued for approximately 50 Geologic survey of Marie Byrd Land million years. The advent of glaciation was early in F. ALTON WADE the period and, according to LeMasurier (1972), has continued without significant deglaciation since The Museum Eocene time. Texas Tech University The insular units that comprise this portion of Detailed studies and analyses of the rock specimens Antarctica are of continental crustal material. It is from Marie Byrd Land and of the field data recorded believed that they were at one time united with the during the field seasons 1966-1967 and 1967-1968 East Antarctic craton. The basement rocks of Oates are still in progress. These are being supplemented Land appear to resemble most closely those of Marie by studies of rock specimens and field data obtained Byrd Land. Too little is known, however, of the during the 1934 Byrd Antarctic Expedition II and early geologic history of Oates Land for a reliable the U.S.