These zircon data provide further evidence for charnockiticplutonic activity and granulite -facies metamorphism 900-1100million years ago in an east-west trending belt exposed inwestern Enderby Land, Mac. Robertson Land, and the IngridChristensen Coast.

This research was supported by National Science Founda-tion grants DPP 75-17390 and DPP 76-80957 to the University ofCalifornia, Los Angeles. Grew thanks members of the 18thand 19th Soviet Antarctic Expeditions for their logistic supportand cooperation.

References

Fedorov, L. V., and Grikurova, D. V. 1980. Sillimanitsoderzhashchiyeredkozemelnyye pegmatity kholmov Reynbolt (VostochnayaAntarktida) [Rare earth pegmatites containing sillimanite of Rein-

bolt Hills (East Antarctica)]. Trudy Sovetskoy Antarkticheskoy Ekspe-ditsii, 70, 107-111.

Grew, E. S. 1978. Precambrian basement at Molodezhnaya Station.Geological Society of America Bulletin, 89(6), 801-813.

Grew, E. S. 1980. Sillimanite and ilmenite from high-grade metamor-phic rocks of Antarctica and other areas. Journal of Petrology, 21(1),39-68.

Grew, E. S., and Manton, W. I. 1977. Age of zircons from pegmatiteat Reinbolt Hills, Ingrid Christensen Coast, Antarctica (70°30'S.,72°30'E.). American Geophysical Union Transactions, 58, 1250.(Abstract)

Ravich, M. G., Solovyev, D. S., and Fedorov, L. V. 1978. Geologiches-koye stroyeniye Zexli Mak-Robertsona (Vostochnaya Antarktida) [Geo-logical structure of Mac. Robertson Land (East Antarctica)]. Lenin-grad: Gidrometeoizdat.

Tingey, R. J . In press. The geological evolution of the Prince CharlesMountains—An antarctic Archaean cratonic block. In C. Craddock(Ed.), Antarctic geoscience. Madison: University of Wisconsin Press.

Petroleum resources of Antarctica*

JOHN C. BEHRENDT

U.S. Geological SurveyDenver, Colorado 80225

There are no known petroleum resources in Antarctica, andinformation on which to base reliable estimates of undiscov-ered resources is lacking. Given the hostile antarctic environ-ment, only giant fields (approximately 70 million tons, or 0.5billion barrels), or more probably supergiant fields (approxi-mately 700 million tons, or 5 billion barrels), could reasonablybe considered economical in the next few decades. Consider-ing the locations of known giant oil fields in the world, Ant-arctica does not appear a very good prospect. The location ofAntarctica in the Gondwanaland reconstruction suggests thatWest Antarctica is the area most likely to contain petroleumresources. Probably only the continental margins (possibly

*This paper will be published in Mineral Resource Potential of Antarcticaby I . Splettstoesser (University of Texas Press).

including ice-shelf areas) bordering the Ross, Amundsen, Bel-lingshausen, and Weddell Seas will be exploitable with presentor future technology because of the several-kilometers-thickmoving grounded ice sheet covering the rest of Antarctica.

Geophysical data are sparse but do suggest the presence ofseveral kilometers of unmetamorphosed sedimentary rock(possibly Cretaceous and Tertiary age) beneath the Ross andWeddell continental shelves. There is no information on theAmundsen and Bellingshausen continental shelves. SeveralDeep Sea Drilling Project (osDr') holes beneath the Ross con-tinental shelf have shown the presence of Tertiary marine andnonmarine sedimentary rocks as old as Oligocene in age over-lying early Paleozoic basement. Shows of gas in the DSDP holes,although provocative, cannot be considered evidence of anyhydrocarbon resources. Technology to exploit possible petro-leum resources in Antarctica is developing faster than thescientific studies directed at resource assessment and environ-mental hazards, and faster than the international legal processof establishing a mineral resources regime to determinewhether, or under what circumstances, industrial explorationand exploitation should be permitted. As future geophysicaland geologic studies outline possible prospective areas, sci-entific studies are needed of hazards associated with geologic,meteorologic, and oceanographic conditions, as well as eco-systems that might be affected adversely.

Tectonic studies in the Scotia Arcregion and West Antarctica

IAN W. D. DALZIEL

Lamont-Doherty Geological Observatory of Columbia UniversityPalisades, New York 10964

My students and I were involved in two major field studiesduring the 1980-81 austral summer. The first involved a con-tinuation of work in the southernmost part of the Andean

Cordillera undertaken by scientists from Lamont-Doherty overthe past 12 years. The second involved a new venture in WestAntarctica undertaken in cooperation with scientists of theBritish Antarctic Survey (see Doake and Crabtree, AntarcticJournal, this issue).

With the absence of RIVHero as a result of her major overhaul,the South American work was limited to the foothills of theAndean Cordillera. Here Terry Wilson completed a detailedstructural traverse from the outcrop of the Upper JurassicTobifera Formation through the folded and thrusted Lowerand Upper Cretaceous strata of the foreland fold and thrustbelt to the outcrop of the Tertiary. This traverse was located inthe district of Ultima Esperanza near the spectacular Miocenegranitic pluton of Cerro Paine. The structures in the area stud-

1981 REvIEw 7

ied consist of a north-northwest-trending set of major foldswith subordinate thrusts. The existence of previously unrec-ognized major folds was determined from detailed study ofminor-fold geometry as well as reinterpretation of some Cre-taceous stratigraphic boundaries. The folds involve Upper Jur-assic through Upper Cretaceous rocks, while Tertiary sedi-mentary rocks occur in a monoclinal belt along the easternedge of the study area. A well-devloped cleavage is presentthroughout. A structural profile of the transect is being con-structed.

Wilson also measured detailed stratigraphic sections in theLower Cretaceous rocks. Together with sedimentologic dataand petrographic results, these sections will provide a moredetailed understanding of the early evolution of the Magal-lanes basin.

The cooperative Lamont-Doherty- British Antarctic Survey(BAS) geophysical study involved radar ice-echo sounding bya BAS "Twin Otter" aircraft (using fuel left by the United Statesin the Ellsworth Mountains at the end of the 1979-80 season)to fly along tracks jointly selected for their tectonic as well asglaciological significance. The main objective was to improveour understanding of the morphology and interrelationshipsof the obvious continental blocks of the Antarctic Peninsula,Ellsworth Mountains, and Thurston Island areas. The aircraftalso obtained profiles across major glaciers within the Ells-worth Mountains and along gravity traverses measured pre-viously by Robert Rutford.

A total distance of 15,700 kilometers was flown in 78.5 hoursusing all the fuel available. Four lines were flown at maximumrange of the aircraft to the Bryan Coast and Pine Island Glacier,four lines at maximum range over the Ronne Ice Shelf towardsthe Antarctic Peninsula, and two lines covering local featureswithin and around the Ellsworth Mountains.

The survey delimited the catchment area of Pine Island Gla-cier and gave valuable information on the nature of the sub-ice surface as well as the sub-ice topography itself (Doake andCrabtree, Antarctic Journal, this issue).

The British Antarctic Survey scientists most closely involvedwith the work are Charles Swithinbank, head of the EarthSciences Section, Christopher Doake, and Richard Crabtree.Peter Clarkson, Geoffrey Renner, and Michael Thomson par-ticipated in planning the flight program.

The work in the Scotia Arc region is supported by NationalScience Foundation grant DPP 78-20629. The cooperative pro-gram in the interior of the continent is supported by NSF grantDl'? 79-20220. The invaluable efforts of the British AntarcticSurvey air unit under the command of Captain Gary Studd isgratefully acknowledged.

Reference

Doake, C. S. M., and Crabtree, R. D. Airborne radio echo soundingin Ellsworth Land and Ronne Ice Shelf. Antarctic Journal of the U.S.,16(5).

Preliminary bivalve zonation of theOrville Coast may be considerably more than the 830 metersmeasured by Thomson and others (1978, p. 9). While the FossilLatady Formation Bluff Formation of Alexander Island (figure 1) accumulated ina fore-arc environment to the west of the peninsula, the LatadyFormation has generally been interpreted as a back-arc deposit

J. A. CRAME (Suarez 1976).

British Antarctic SurveyNatural Environment Research Council

Madingley RoadCambridge CB3 OET, England

A primary aim of the 1977-78 U.S. Geological Survey fieldparty to the Orville Coast (figure 1) was to investigate thebiostratigraphy of the Jurassic Latady Formation, which is wellexposed in this region. Preliminary results of this fieldwork(Rowley 1978, 1979; Thomson, Laudon, and Boyles 1978)include synopses of the paleontology. In addition, Thomson(1980) has given a brief review of the principal ammonitefaunas. This article is a complementary report on another fossilgroup with considerable biostratigraphic potential, thebivalves.

Predominantly composed of shallow-water volcaniclasticsediments, the Latady Formation is now known to be one ofthe major sedimentary formations of the Antarctic Peninsula.It can be traced from the Lyon Nunataks-Behrendt Mountainsregion through the Orville and Lassiter coasts to the southernBlack Coast (figure 1) (Rowley 1978; Thomson et al. 1978). Lackof continuous exposures and considerable tectonic deforma-tion mean that the true thickness of the formation on the

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Figure 1. Map of the Orville Coast region. The shaded area on theInset shows the relationship of this region to the Antarctic Penin-sula. The numbers 1, 2, and 3 refer to the Lassiter Coast, southernBlack Coast and Alexander Island, respectively.

8 ANTARCnc JOURNAL