Badania paleolimnologiczne i geomorfologiczne na Wyspie Króla Jerzego, Antarktyka Zachodnia (1984-1986)

Abstract

PALEOLIMNOLOGICAL AND GEOMORPHOLOGICAL INVESTIGATIONS ON THE KING GEORGE ISLAND, WEST ANTARCTICA (1984-1986) Summary The cores of bottom sediments from five lakes were taken during the austral winter 1985. Four lakes were localized on King George Island, and one on the tip of Antarctic Peninsula (Fig. l). Investigated lakes belonged to different types and represented different genesis and trophy. Hotel Lake on Fildes Peninsula (Fig. 2) is laying high on the flat platform (50 m a.s.1.), far away from the glacier, in astomosin system of meltwater channels. The age sequence of sediments in taken core should be here the longest one. The lake sediment- detritus gyttja is divided in this core into two parts (upper and lower one) by more than 1.5 m thick layer of alluvial sand, composed mainly of volcanic ash. Many other thin (below 0.5 cm) horizons of volcanic (?) ash fallout was recognized in gyttja sediments, not only in Hotel Lake. Near-shore Kitezh and Dlinnoe Lakes on Fildes Peninsula (Fig. 3-5) had been developed from the sea bays after separation from the sea by the beach. Now the beach and lakes are elevated to the altitude 16 m a.s.l. (Fig. 4). The changes of sedimentation resulted from those events are in cores very clear. Detritus gyttja laying on the sea sediments contains plenty of organic matter what makes possible to carry out father detailed study upon history both lakes using 14C method. Proglacial and oligotrophic Rudy Lake on Potter Peninsula (Fig. 6) was developed during several stages of deglaciacion. Each one stage caused change into scheme of surrounding moraines, as well as in shape and size of the lake. It is possible to reconstruct this history studying mineral, often laminated bottom sediments in different basins of the lake, and studying ancient and recent outflows from lake to the sea (Fig. 7). Rudy Lake was formed during deglaciacion in neoglacial event, like the peat bank in central part of Rescures Hills (Fig. 10). Proglacial Boeckella Lake on Antarctic Peninsula (Fig. 8) was developed in geomorphological conditions similar as Rudy Lake but under influence of solutions rich in nutrients coming from the large penguin rookery situated on the shore of the lake. The eutrophication of the lake caused abundance of amorphic organic matter occurring in clearly laminated sediments. The influence of the birds has been noticed from the beginning of lake history. Interesting sequence of the Holocene features were found near the Arctowski Station. The movement down of rookeries following isostatic elevation of the island was recognized along the Penguin Ridge. The traces of ornithogenic phosphates in soil and plenty of penguin bones were discovered here on the transfer way up to recent rookery. The ornithogenic remnants were laying also on the raised stony (?) beach 45 m a.s.l. (Fig. 9). The age of the peat occurring over it in the alluvial sand was 4950 ±140 y. B.P. (Birkenmajer - 3). Thus colonization by penguins had been started here in the Early Holocene. Burried ornithogenic soils were found also in other places on King George Island: Stranger Point, Low Head and Blue Dyke.