Badania paleontologiczne V Polskiej Wyprawy Antarktycznej Polskiej Akademii Nauk (1980-1981)

Andrzej Gaździcki, Ryszard Wrona

Abstrakt


PALEONTOLOGICAL STUDIES CARRIED OUT DURING THE VTH ANTARCTIC EXPEDITION OF THE POLISH ACADEMY OF SCIENCES

Summary
The paleontological studies carried out in the King George Island, South Shetland Island (Western Antarctica) during the austral summer 1980-1981, were primarily concentrated on highly fossiliferous marine deposits discovered in the Melville Peninsula (Fig. 1). In that area, there is exposed (see cover ph9to) over 200 m sequence of calcareous-marly and, sometimes, somewhat sandy deposits. Preliminary analysis of faunal and floral assemblages showed that the deposits range in age from the Middle to Upper Cretaceous. The deposits were found to yield coccoliths, diatoms, silicoflagellates, foraminifers, corals, bryozoans, polychaetes, gastropods, bivalves, scaphopods, belemnites, ostracods, crabs, asteroids, echinoids, fisches, and they display numerous tunnels made by •crabs as well as mass occurrence of coprolites. Vagile benthos clearly predominates in the studies faunal assemblage which appears typical of a shallow shelf zone with relatively quiet sedimentation.
The other important area of studies is situated in the Low Head - Lions Rump region, where marine Pliocene deposits are exposed (Figs. 1 - 2). Attention should be mainly paid to the lower, Low Head Member (= Pecten Conglomerate), belonging to the Polonez Cove Formation (K. Birkenmajer (2 - 3)). Deposits of that member are very rich in fossils, especially coccoliths, diatoms, both benthic and planktonie foraminifers, bryozoans, polychaetes, brachiopods, gastropods, bivalves, scaphopods, ostracods, ophiuroids and echinoids. There were also found algal (? Rhodophyta) encrustations and coatings and single stromatolite structures. Attention should be paid to numerous bivalve layers. Local allochtoneous accumulations of shells of bivalves mainly representing the species Chlamys anderssoni (Henning, 1911) may be explained by sedimentary conditions related to heavy storms. It is also worth to note the discovery of three lithological horizons with pholad burrows in the Mazurek Point area. The localities with marine fauna buried in vivo make possible paleoecological reconstructions for the Polonez Cove Formation.
Several floral localities were also revisited and exploited. A large collection of well-preserved imprints of leaves, fragments of stalks and trunks and single pollen were gathered in the Dufayel, Cytadela, Fildes Peninsula - „Mt. Flora", Potter Cove (region of Argentina Teniente Jubany Station) and Mt. Wawel localities (Fig. 1). The Mt. Wawel locality is of special importance on account of the record of the youngest (? Upper Miocene) flora in the King George Island.
In the Low Head - Lions Rump region, Melville Peninsula and Vaureal, paleoglacial deposits were sampled for boulders of sedimentary, especially carbonate rocks of Antarctic origin. Light-coloured varieties of limestones often yield crushed a-ryhaeocyathid cups and trilobite armature. The boulders appear completely exotic for the King George Island and preliminary analyses show that they were brought here either as morainic material or deposited as dropstones by icebergs coming from distant Ellsworth Mts or Transantarctic Mts.

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