Polish Polar Research

A sequence of glacial deposits up to 4 m thick unconformably overlies the Eocene La Meseta Formation on the Seymour Island plateau (meseta) and forms a lithostratigraphically distinct unit in the succession of the James Ross Basin, which is formally named here as the Weddell Sea Formation. The formation is thus far known only from Seymour Island. This is a terrestrial melt-out till which contains abundant erratics and also reworked Cretaceous–Tertiary micro- and macrofossils within a silty clay matrix. The terrestrial origin of this till is shown by glacial striations at the base of the unit. The largest erratics (up to 3 m in diameter) are composed of plutonic (granitoids) and metamorphic (gneiss and crystalline schist) rocks of the Antarctic Peninsula provenance. Smaller in size and much more numerous are erratics of volcanic rocks, represented by andesite, basalt and corresponding pyroclastics of the James Ross Island Volcanic Group. Less common are erratics of sedimentary rocks, sometimes bearing fossils derived from the underlying Tertiary and Cretaceous strata. A few erratics from the top of the studied sequence are conglomerates of the Cockburn Island Formation with a foraminifer fauna. These are the youngest clasts within the Weddell Sea Formation. The presence of the Pliocene index fossil Ammoelphidiella antarctica Conato et Segre, 1974 indicates a lower age limit of latest Pliocene or earliest Pleistocene age. The upper age limit of the formation has not been established. An encrusting, unilamellar, colony of the bryozoan Escharella Gray, 1848 has been found on the one of erratics from the Weddell Sea Formation. This is the first fossil record of this genus in Antarctica.

Deep seismic sounding measurements were performed in the continent-ocean transition zone of north-western Spitsbergen , during the expedition ARKTIS XV/2 of the RV Polarstern and the Polish ship Eltanin in 1999. Profile AWI-99200 is 430 km long and runs from the Molloy Deep in the Northern Atlantic to Nordaustlandet in north-eastern Svalbard . Profile AWI-99400 is 360 km long and runs from the Hovgĺrd Ridge to Billefjorden. Seismic energy (airgun and TNT shots) was recorded by land (onshore) seismic stations (REF) and ocean bottom seismometers (OBS) and hydrophone systems (OBH). Good quality refracted and reflected P waves were recorded along the two profiles providing an excellent data base for a detailed seismic modelling along the profile tracks. Clear seismic records from airgun shots were obtained up to distances of 200 km at land stations and 50 km at OBSs. TNT explosions were recorded even up to distances of 300 km . A minimum depth of about 6 km of the Moho discontinuity was found east of the Molloy Deep. Here, the upper mantle exhibits P-wave velocity of about 7.9 km/s, and the crustal thickness does not exceed 4 km . The continent–ocean transition zone to the east is characterised by a complex seismic structure. The zone is covered by deep sedimentary basins. The Moho interface dips down to 28 km beneath the continental part of the 99200 profile, and down to 32 km beneath the 99400 profile. The P-wave velocity below the Moho increases up to 8.15 km/s. The continental crust consists of two or three crystalline layers. There is a lowermost crustal continental layer, in the 99400 profile’s model, with the P-wave velocity in order of 7 km/s, which does not exist in the continental crust along the 99200 profile. Additionally, along the 99200 profile, we have found two reflectors in the lower lithosphere at depths of 14–42 and 40–50 km dipping eastward, with P-wave velocity contrasts of about 0.2 km/s. The characteristics of the region bears a shear-rift tectonic setting. The continent–ocean transition zone along the 99200 profile is mostly dominated by extension, so the last stage of the development of the margin can be classified as rifting. The uplifted Moho boundary close to the Molloy Deep can be interpreted as a south-western end of the Molloy Ridge. The margin in the 99400 profile area is of transform character.

Ground temperature variations have been analysed to the depth of 160 cm, with respect to meteorological elements and short-wave radiation balance. The database of the ground temperature covers a thirteen month-long period (May 1992 – June 1993), which included both the seasons of complete freezing of the ground and thaw. Special attention has been given to the development of perennial permafrost and its spatial distribution. In summer, the depth of thawing ground varied in different types of ground — at the Polish Polar Station, this was ca. 130 cm. The ground froze completely in the first week of October. Its thawing started in June. The snow cover restrained heat penetration in the ground, which hindered the ground thawing process. Cross-correlation shows a significant influence of the radiation balance (K*) on the values of near-surface ground temperatures (r2 = 0.62 for summer).

This publication begins series of papers on taxonomy of juvenile and little known Mesozoic gastropods from Siberia and Timan region (= Pechora Basin). First part contains general part with geological framework followed by the paleontological part on taxonomy of Vetigastropoda and Caenogastropoda (exclusive of Neogastropoda). Described are 15 species of gastropods. Three of them are new. They are Chuelskia siberica (Trochidae), Ageria gankinensis (Epitoniidae), and Dzikella chuzikovensis (superfamily and family uncertain). Moreover, described is a new genus Chuelskia (Trochidae). Eight species are left in the open nomenclature. The Siberian gastropods belong mostly to the cosmopolitan fauna while the gastropods of Timan region are the same as those already described from Novaja Zemlja Islands.

The cephalopod diet of the gentoo penguin, Pygoscelis papua and the Antarctic fur seal, Arctocephalus gazella was comparatively analyzed at Laurie Island, South Orkney Islands. A total of 125 stomach samples were collected by the water off-loading method from gentoo penguins during the autumns of 1993, 1995 and 1996, and 39 fur seal scats were collected from mid March to April 1988. Cephalopods preyed upon by gentoo penguins were represented by 1974 beaks (1628 lower, 346 upper) which occurred in 50.4% of the samples. Lower beaks identified belonged exclusively to the squid Psychroteuthis glacialis. The mean lower rostral length (LRL) of these beaks was 1.1 mm (range 0.4– 1.8 mm). From the Antarctic fur seal scats 103 beaks (41 lower, 62 upper) were removed from 60.6% of scats which contained prey remains. The cephalopod species identified were Slosarczykovia circumantarctica and P. glacialis which constituted 78.8% and 21.1% in terms of numbers, respectively. The mean lower rostral length for S. circumantarctica was 2.7 mm (range 2.0–3.5 mm), while that of P. glacialis was 1.6 mm (range 1.0–2.5 mm). The foraging behaviour of the two top predators was analyzed and discussed according to the composition and size of their cephalopod prey.

Zooplankton community composition, abundance and biomass from two polar localities – Kongsfjorden (Arctic) and Admiralty Bay (Antarctic) is compared. The community composition of zooplankton in both polar regions included similar taxonomic groups and the diversity at the species level was similar. Even though the overall species composition was different, some species were common for both ecosystems, for example Oithona similis, Microcalanus pygmaeus or Eukrohnia hamata. The abundance and biomass of the main zooplankton components (Copepoda) differed greatly between the two ecosystems, both being of an order of magnitude higher in Kongsfjorden than in Admiralty Bay. Kongsfjorden is situated at the border of two regions what induces high productivity with copepods playing an important role, and there is also a strong advection into the fjord. Admiralty Bay is adjacent to the homogenous Antarctic oceanic ecosystem; some advection into the bay occurs as an effect of tide and wind driven processes. Antarctic krill, which was not included in the present study, occupies most of the primary consumers niche and replaces copepods at the second trophic level.