Glaciology and Glacial Chronology in the South Shetland Islands
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day variation of parameters measured in the Byrd oble, France. The trace element samples we -e col- Station core that have paleoclimatic significance, and lected for Dr. C. Boutron, of the same laboratory, for (3) studied the flow of the ice sheet at an undulation neutron activation and atomic absorption analyses. in surface topography. The oxygen isotope program is in cooperationwith Sedimentary processes were studied in detail over Drs. W. Dansgaard and S. J. Johnsen, Geop ysical the undulation in surface topography in the detailed Isotope Laboratory, University of Copenhagen, Den- study area. At three locations snow samples at 2-centi- mark. Mr. Thompson will analyze the sampls col- meter intervals to 3 meters in depth and whole cores lected for microparticle analysis at the Institute of to 10 meters in depth were collected for oxygen isotope Polar Studies. (8180) analysis to determine the relative contributions We were in the field from December 4, 1973, to of summer and winter balances at sites of different February 7, 1974. In addition to the authors, the field surface slope and to investigate the horizontal conti- party included Messrs. T. H. Baughman, D. J . Rugh, nuity of distinctive 6180 horizons. Correlative cores for J. H. Wells, and C. F. Welistead. This research was analysis of microparticle content and size distribution supported by National Science Foundation grat ov- were collected to determine the seasonal and topo- 26137X. graphic variation of microparticulate fallout. The ex- periments for firn densification (Dewart and Whillans, References 1970; Whillans, 1972) were remeasured, and a line of stakes spaced 125 meters apart were measured at fre- Dewart, G., and I. Whillans. 1970. Geophysical and glaci- quent intervals to determine the topographic effect of ological studies along the Byrd Station strain net, 1969- individual storms. At 9 sites along the undulation, 1970. Antarctic Journal of the U.S., V(4): 111-112. Johnsen, S. J., W. Dansgaard, H. B. Clausen, and C. C. 10-meter mean samples were collected for hydrogen Langway, Jr. 1972. Oxygen isotope profiles through the isotope (deuterium) analysis to determine if there is a antarctic and Greenland ice sheets. Nature, 235: 429- correlation between deuterium content and balance as 434. was found in Adélie Land (Lorius, 1963, fig. 44). Lorius, C. 1963. Le deutérium: possibilités dapplication Two sites were selected for trace element sampling to aux problèmes de recherche concernant la neige, le névé, et la glace dans lantarctique. Comité National Fran cais test the possibility of local variations in trace element des Recherches Antarctiques, 8. 102p. content of the snow. Thompson, L. G. 1973. Analysis of the concentration of On a longer scale the same kinds of samples were microparticles in an ice core from Byrd Station, Antarc- collected from pits and by coring in the region of the tica. Columbus, The Ohio State University Research Foundation, Institute of Polar Studies. Report, 46. 43p. ice divide and at other locations to compare processes Ueda, H. T. and D. E. Garfield. 1968. Deep-core drilling with those in the detailed study area. Temperatures program at Byrd Station (1967-1968). Antarctic Jour- were obtained from the bottom of 10-meter holes and nal of the U.S., 111(4): 111-112. all poles were measured and firn densities were ob- Whillans, I. M. 1972. Ice-sheet dynamics near Byrd Station. Antarctic Journal of the U.S., VII(4) : 111. tained to calculate mass balance. Using a sidewall Whillans, I. M. 1973. State of equilibrium of the west antarc- sampler, supplied by Dr. S. J . Johnsen, mean samples tic inland ice sheet. Science, 182: 476-479. to 2 meters in depth for 6180 were obtained at 3- kilometer intervals along the Byrd Station strain net- work, and more frequently in the detailed study area. Near-surface firn samples also were taken from pits along the flowline from the ice divide to Byrd Station. Glaciology and glacial chronology In From these samples the effect of variations in mass the South Shetland Islands balance and mean annual temperature on microparti- cle deposition patterns will be determined. These data will enable full interpretations of the microparticle JAMES E. CURL (Thompson, 1973), oxygen isotope (Johnsen et al., Institute of Polar Studies 1972), and temperature (Ueda and Garfield, 1968) The Ohio State University profiles obtained from the Byrd Station drill hole. Columbus, Ohio 43210 The ice movement studies previously have been described (Dewart and Whillans, 1970; Whillans, NORMAN W. TENBRINK 1972) and this season completes these experiments. Department of Geology Unfortunately, due to less field time than needed, the Grand Valley State Colleges horizontal trilateration of the detailed strain network Allendale, Michigan 49401 was only about two-thirds completed. The leveling and seismic programs were satisfactorily completed. The deuterium sampling program is in cooperation Field work on Livingston and King George h with Dr. C. Lorius, Laboratoire de Glaciologie, Gren- (fig. 1), from January 10 to March 15, 1974, 168 ANTARCTIC JOURNAL 58°W 0° SOUTH SHETLAND ISLANDS ING GEORGE DISLAND 62°S —1cc I NELSON/- ISLAND ROBE RI ISLAND T GREENWICH ISLAND START AREA OF MAJOR POI FIELD INVESTIGATION tpa LOCATION OF GLACIER- FI ICE STUDIES SNOW .J4SLAND ECEPTION SL AND f 630 TRINITY 60°W PENINSULA Figure 1. Location of the South Shetland Islands, showing the locations of major field investigations and glacier-ice studies. sisted of a combined program of glaciology and glacial ing traverses of the major ice-free portions of Living- geology. Our goal was to complete a reconstruction ston and King George islands. These traverses in- of the glacial history of the northern Antarctic Penin- cluded detailed investigations of raised beaches and sula region by expanding an incomplete record of moraine-beach relatiQnships. For chronologic determi- glacial history previously obtained from the South nations, radiometrically datable organic remains were Shetland Islands. Although previous glacial geologic collected from in situ deposits within the raised beach knowledge of the South Shetland Islands includes a features. (Samples of whale and sea bones were col- partially dated, threefold sequence of glacial advances lected from recently living animals in the field area to (Everett, 1971; John, 1972; TenBrink and Curl, limit the radiocarbon reservoir age of present antarctic 1973), a complete glacial history cannot be established seawater.) until a detailed chronology is determined. Therefore, An internally consistent set of measurements of se- the primary objective of the 1973-1974 field program lected crustose lichen thalli were made on recent Liv- focused on establishing a complete chronology of past ingston Island moraines. Maximum thalli diameters, glacial variations in the South Shetland Islands in compared to the adjusted growth rate curves for lich- order to evaluate these variations in terms of their ens of the South Orkney Islands (D. C. Lindsay, climatic significance. personal communication), will permit a system of The field party consisted of four geologists from the lichenometric ages to be established for several mo- Institute of Polar Studies: Messrs. Curl (party raines. leader), Doyle R. Watts, James E. Birchall, and Frank At Potter Cove, King George Island (fig. 2), a Mikan. Assistance in accomplishing a portion of the threefold sequence of moraines was mapped in detail glaciological program was provided by Dr. Olav Or- and oriented cores were drilled from andesitic erratics heim, Norsk Polarinstitutt, Oslo, Norway. of traceable origin that may prove suitable for alter- Glacial geologic investigations were conducted dur- nating field demagnetization dating techniques (Heller July—August 1974 169 .0 (ICE- PIT STUDIES 1 KING GEORGE ISLAND / 4 3 K m. ) LJ —LJ \\\N_) N I LSUmELD POINT Camp-2 L3 .5 2.4 7 Flat 6.8 flt98m. TO 11.0 f J I) 13.. NORTHOSPIT A Hora io ARDLEY 16.0 StU4 ISLAND Hill AFlor ^nce SOUTH 295 7. SPIT 275% 16.0 marin beach E 35.0 63 \ c 4laci IlATO PEN IOS Camp RAITS N, RIP POI NT / he \\\ U rs 1i d.L 46 4 EXPLANATION Ice margin Ice-pit location STRANGER 0 .. Drainage or POINT Residual surface * L_/ (marine or subaerial) ......, scour chanr el 55.0 Raised beach I1 Ice-cured moraines 15 (marine) NELSON ISLAND ALL ELEVATIONS H6 M 0 sic ridgesd ca. Ice-molded surface IN METERS PRELIMINARY RELEASE Figure 2. Index map of Maxwell Bay, King George Island, indicating the types and locations of field studies conducted in 1973-1974. and Market, 1972). Similar studies of marine strand- were dug in glaciers on Livingston and King George lines and moraine-beach relationships also were con- islands according to guidelines recommended by Dr. ducted on Keller Peninsula (fig. 3); the results gen- W. Dansgaard, Geophysical Isotope Laboratory, Uni- erally support the Maxwell Bay and Livingston Island versity of Copenhagen, Denmark. Three pits were observations. located on Rotch Ice Dome at elevations of 150, 250, With the aid of a recording sonar system aboard and 350 meters. One pit was excavated on top of the R/V Hero, Maxwell Bay was systematically sounded ice dome to the east of Fildes Peninsula, King George for detection of possible submarine moraines and ter- Island (fig. 2), at an elevation of 300 meters, and a race systems. Some glacial and sea level fluctuations final pit was located on the Stenhouse Glacier, Ad- not recorded as terrestrial deposits may be interpreted miralty Bay (fig. 3) near the geographic summit at an from the sonar data. altitude of 548 meters. I The following major objectives of the glaciological Each pit was excavated to a depth sufficient to ex- field program were completed. Mass balance stake pose at least two summer surfaces. The pit stratig- networks on Rotch Ice Dome, Livingston Island, and raphies were recorded and samples for oxygn6/ glacier G-1, Deception Island, were remeasured and oxygen 18 paleotemperature determinations were pro- expanded for the fifth consecutive season.