Polish Polar Research

In the framework of the 4th International Polar Year Panel “Plate Tectonics and Polar Gateways” the international project “The Dynamic Continental Margin Between the Mid-Atlantic-Ridge System (Mohns Ridge, Knipovich Ridge) and the Bear Island Region” was undertaken in 2007-2008. As a part of this project a new three-component seismic broadband station was installed in September 2007 in the area of the Polish Polar Station Hornsund in Southern Spitsbergen . The new HSPB station has the coordinates: Φ = 77.0019°N, λ = 15.5332°E, H = 11 m a.s.l. During the first years of operation a number of good quality teleseismic events were recorded. This gives the opportunity for a first determination of crustal and mantle structure beneath the station by using receiver function (RF) and SKS splitting techniques. The Moho depth determined using RF is about 32 km beneath HSPB. Significant amplitudes on the transverse components of the RF indicate a shallowly dipping discontinuity (sedimentary-basement) towards the south-west. The fast polarization of SKS phases is near parallel to the border between the continental and the oceanic crust and the Hornsund fault (α = 151.8°). The average time delay dt between “fast” and “slow” directions is 0.68 s, which implies ca. 2% anisotropy in a 100- 200 km thick layer in the mantle.

The near-surface ice thermal structure of the Waldemarbreen, a 2.5-square km glacier located at 78°N 12°E in Spitsbergen, Svalbard , is described here. Traditional glaciological mass balance measurements by stake readings and snow surveying have been conducted annually since 1996. The near-surface ice temperature was investigated with automatic borehole thermistors in the ablation and accumulation areas in 2007-2008. The mean annual surface ice temperatures (September-June) of the ablation area were determined to be -4.7°C at 1 m depth and -2.5°C at 9 m . For the accumulation area, they were -3.0°C at 2 m , and -2.3°C at 10 m depth between September and August. On the Waldemarbreen, at 10 m depth, the mean annual near-surface ice temperature was 4.0°C above the mean annual air temperature in the accumulation area. The Waldemarbreen may thus be classified as a polythermal type with cold ice which is below the pressure melting point and a temperate ice layer in the bottom sections of the glacier and with a temperate surface layer only during summer seasons. At a depth of 10 m , temperatures are of the order of -2°C to -3°C.

Formerly reported as maritime Antarctic Bacidia sp. A has been re-named here as B. chrysocolla Olech, Czarnota et Llop. Another new species, B. subcoprodes Olech et Czarnota, found in the continental and maritime Antarctic has also been described here. A placement of both taxa within Bacidia De Not. is probably tentative because they are not congeneric with the type of this genus, B. rosella (Pers.) De Not. Similarities to other Bacidia with Laurocerasi-brown hypothecium and mostly 3-septate ascospores are discussed.

Arthropod carapaces have been recovered from the Early Cambrian fossiliferous limestone erratics (dropstones) in the Early Miocene glaciomarine Cape Melville Formation of King George Island (South Shetland Islands), West Antarctica. The arthropod fauna comprises the bradoriide carapaces of Albrunnicola bengtsoni Hinz-Schallreuter, Liangshanella birkenmajeri sp. nov., Melvillella corniculata gen. et sp. nov., Mongolitubulus squamifer Missarzhevsky, Zepaera sp., the phosphatocopid Dabashanella sp., and one problematic taxon. With the exception of M. squamifer, all described species are recorded from Antarctica for the first time. The described Antarctic bradoriide assemblage attests to a close relationship with similar faunas from South Australia and South China, but also includes more widely distributed taxa extending the relationship to the palaeocontinents of Siberia, Baltica and Laurentia.

The Blue Dyke and Jardine Peak are subvertical hypabyssal intrusions cutting a stratiform volcanic sequence in the Admiralty Bay area on King George Island (South Shetlands, Antarctica ). The rocks are porphyritic, crystal-rich basaltic andesites. Tiny zircon crystals were used for single grain SHRIMP U-Pb dating. The mean ages calculated for the zircon populations from both intrusions indicates Late Oligocene (Chattian) formations. Zircon grains from the Blue Dyke gave the mean age of 27.9±0.3 Ma, whereas those from the Jardine Peak are slightly younger displaying the mean age of 25.4 ± 0.4 Ma: a Late Oligocene (Chattian) crystallization age the inferred of both these intrusions. These are much younger than previous Eocene K-Ar and Ar-Ar ages for such rocks and suggest that formation of the King George Island intrusions can be related to tectonic processes that accompanied the opening of the Drake Passage.