This work was supported in part by National Science Foun-dation grant DPP 88-15976.

References

Cook, E.R., and L.A. Kairiukstis (Eds.). 1990. Methods of dendrochron-ology. Dordrecht: Kluwer Academic Publications.

Creber, G.T. 1990. The south polar forest ecosystem. In T.N. Taylor andE.L. Taylor (Ed.), Antarctic paleobiology: Its role in the reconstruction ofGondwana. New York: Springer-Verlag.

Francis, J. 1986. Growth rings in Cretaceous Tertiary wood from Ant-arctica and their palaeoclimatic implications. Palaeontology, 29(4), 665-684.

Jefferson, T.H. 1982. Fossil forests from the Lower Cretaceous of Alex-ander Island, Antarctica. Palaeontology, 25(4), 681-708.

Spicer, R.A., and J.T. Parrish. 1990. Latest Cretaceous wood of thecentral North Slope, Alaska. Palaeontology, 33, 225-242.

Taylor, E.L. 1989. Tree-ring structure in woody axes from the centralTransantarctic Mountains, Antarctica. In Proceedings of the InternationalSymposium on Antarctic Research. (Hangzhou, P.R. China, May 1989.)Tianjin: China Ocean Press.

Studies of graniticand metamorphic rocks,

Horlick and Whitmoremountains area

S.G. BORG, D.J. DEPAOLO, E.E. DALEY,and K.W.W. SIMS

Berkeley Center for Isotope GeochemistryDepartment of Geology and Geophysics

University of CaliforniaBerkeley, California 94720

This paper reports on field work on the granitic and meta-morphic basement rocks of the Transantarctic Mountains dur-ing the 1990-1991 austral summer. It supplements previousreports in Antarctic Journal (see Borg and DePaolo 1990).

Geologic mapping and sampling of granitic and metamorphicrocks were carried out in the Horlick Mountains (including theWisconsin Range, the Ohio Range, Long Hills, MetavolcanicMountain, and Minna Spur) and the Whitmore Mountains dur-ing the 1990-1991 austral summer. This was accomplished witha combination of Twin Otter support and ground traverses. Inearly December, a tent camp, including several fuel drums forTwin Otter operations, was placed by LC-130 about 4 kilometersnorth of Metavolcanic Mountain on the east side of the upperReedy Glacier (figure) for later occupancy. The field party andgeologic field equipment were staged at the Corridor Aerogeo-physics of the Southeastern Ross Transect Zone (CASERTZ)camp (figure) for Twin Otter operations. An additional fuelcache was established in the northwestern Horlick Mountainsby the Twin Otter crew prior to beginning science support. TheTwin Otter was used in a close-support role for reconnaissancegeologic mapping and sampling directly from the CASERTZcamp. Although the CASERTZ camp was approximately 1 hourflight time from the nearest outcrop, it provided access to alarge segment of the Transantarctic Mountains, from the upperReedy Glacier to the Whitmore Mountains. In a close-supportrole, the Twin Otter proved to be ideal for our purposes, pro-viding a large operational area with the ability to land withinwalking distance of outcrops. About 1,600 kilograms of rockwas collected representing all the basement lithologies (79 sam-ples from 46 localities).

Our work follows up on reconnaissance studies done in theHorlick Mountains by J. Murtaugh and G. Faure in the late

1960's (Murtaugh 1969; Faure, Murtaugh, and Montigny 1968).Our goal is to characterize the crystalline basement rocks interms of their neodymium, strontium, and oxygen isotopiccompositions and to delineate crustal provinces (see Borg andDePaolo 1990; Borg, DePaolo, and Smith 1990).

The basement in the Horlick Mountains region is composedof granitic and metamorphic rocks (see Murtaugh 1969). Themetamorphic rocks include both metasedimentary and metaig-neous lithologies. At Spear Nunatak in the upper Reedy Glacierarea, the metasedimentary rocks are represented by complexlyfolded amphibolite-grade banded gneisses and schists. Thisunit is lithologically similar to the Miller Formation in the upperNimrod Glacier region. In the lower Reedy Glacier area, meta-sedimentary rocks are represented by greenschist facies gray-wacke-shale sequences, probably equivalent to the LaGorceFormation. Metaigneous rocks are represented by dacitic por-phyritic volcanic rocks, probably Wyatt Formation, exposed atMetavolcanic Mountain, in the Mims Spur region, and in theLong Hills. Granitic rocks that have intruded these metamor-phic rocks range from granite to granodiorite and include de-formed and undeformed lithologies. The deformed lithologiesare associated with well-developed shear zones, and there isno compelling field evidence to suggest that any of these gran-ites are significantly older than the undeformed lithologies. Allof the granites in the Horlick Mountains are probably associ-ated with the Cambro-Ordovician Ross Orogeny.

Analytical work is underway to characterize the granites andmetamorphic units. This will allow us to trace basement prov-inces delineated in the Nimrod-Shackleton Glaciers region to-ward the southeast in the Transantarctic Mountains.

We would like to thank National Science Foundation PolarOperations, Kenn Borek Air Ltd., VXE-6, and Antarctic Sup-port Associates, Inc., for their efforts in support of our fieldwork. Special thanks go to Henry Perk, Jim Pearce, and DougGaunt of Kenn Borek Air Ltd., and to Kevin Killilea (managerof the CASERTZ camp) and Rick Campbell (field party liaison)of Antarctic Support Associates. This research was supportedby National Science Foundation grant DPP 88-16925.

References

Borg, 5G., and D.J. DePaolo. 1990. Crustal basement provinces of theTransantarctic Mountains, Ross Sea sector. Antarctic Journal of theU.S., 25(5), 29-31.

Borg, 5G., D.J. DePaolo, and B.M. Smith. 1990. Isotopic structure andtectonics of the central Transantarctic Mountains. Journal of Geophys-ical Research, 95(135), 6647-6667.

24 ANTARCTIC JOURNAL

AntarcticIce Sheet

Murtaugh, J.G. 1969. Geology of the Wisconsin Range Batholith, Trans-antarctic Mountains. New Zealand Journal of Geology and Geophysics,12(2&3), 526-550.

Faure, G., J.G. Murtaugh, and R.J.E. Montigny. 1968. The geology andgeochronology of the basement complex of the central TransantarcticMountains. Canadian Journal of Earth Sciences, 5, 555-560.

SPAntarctica

ITISouthern

cMurdoOU Station

Byrd Glacier

/ Ross Ice Shelf

Nimrod Glacier

Beardmore Glacier

IShackleton Glacier

NorthernVictoria

Land

CO

IIII

0 kilometers 300III

0miles200

V 1..#LUI IQ

Land

çjC

Central

Marie ByrdLand

Ross Sea

180'+ 80'S

IS

TransantarcticScott Glacier

IQ CASE RTZ0Reedy Glacier

Ice SheetWisconsin Range Camp

East Antarctic Mountains

Samples are nowWhitmorebeing processedLight gray shading shows outcrop from this region.Mtns

area in the Transantarctic Mountains.+South Pole Thiel Mtns

Locations in the Transantarctic Mountains.

1991 REVIEW 25