The organodetritic, sandy limestones of the Treskelodden Formation (Late Gzhelian to Early Artinskian) investigated in outcrops at Treskelen Peninsula, Hyrnefjellet mount and Polakkfjellet mount of south Spitsbergen, contain rich foraminiferal assemblages. Fifty eight foraminiferal species of twenty three genera, including two new species (Hemigordius hyrnefjelleti sp. nov. and Midiella arctica sp. nov.) have been identified. Three foraminiferal zones have been defined, with ages of Late Asselian (Pseudofusulinella occidentalis), Sakmarian (Midiella ovata – Calcitornella heathi) and Early Artinskian (Hemigordius hyrnefjelleti – Midiella arctica). Sedimentary features and the biotic history of the studied succession records a Late Paleozoic cooling trend that stays in accordance with Pangaea’s shift to the north.
The organic carbon (OC)-rich, black shale succession of the Middle Triassic Bravaisberget Formation in Spitsbergen contains scattered dolomite-ankerite cement in coarser-grained beds and intervals. This cement shows growth-related compositional trend from non-ferroan dolomite (0–5 mol % FeCO3) through ferroan dolomite (5–10 mol % FeCO3) to ankerite (10–20 mol % FeCO3, up to 1.7 mol % MnCO3) that is manifested by zoned nature of composite carbonate crystals. The d13C (-7.3‰ to -1.8‰ VPDB) and d18O (-9.4‰ to -6.0‰ VPDB) values are typical for burial cements originated from mixed inorganic and organic carbonate sources. The dolomite-ankerite cement formed over a range of diagenetic and burial environments, from early post-sulphidic to early catagenic. It reflects evolution of intraformational, compaction-derived marine fluids that was affected by dissolution of biogenic carbonate, clay mineral and iron oxide transformations, and thermal decomposition of organic carbon (decarboxylation of organic acids, kerogen breakdown). These processes operated during Late Triassic and post-Triassic burial history over a temperature range from approx. 40°C to more than 100°C, and contributed to the final stage of cementation of the primary pore space of siltstone and sandstone beds and intervals in the OC-rich succession.
Solar radiation reflectance was analysed to characterize Arctic ornithogenic tundra developing in the vicinity of large breeding colony of Brunnich‘s guillemots Uria lomvia and kittiwakes Rissa tridactyla at the foot of Gnĺlberget cliff (Hornsund, SW Spitsbergen). Radiometric method was found to be a useful tool for studying structure and functioning of plant formations. We measured reflectance of four wavelengths: 554 nm (YG), 655 nm (RED), 870 nm (NIR) and 1650 nm (SWIR) at 10 plots situated along the transect running from the colony to the sea. Moreover, data of plant community character, species quantitative composition as well as total biomass were collected to relate these parameters with the spectral values. The results showed that radiometric data characterized vegetation well enough to recognize the same plant communities on the basis of spectral reflectance as distinguished with traditional phytosociological methods.
Although the Antarctic has avoided the worst effects of alien species, its future seems endangered due to increasing natural and man-made pressures. Rapid changes in three major environmental variables have occurred in the Antarctic region during the last decades. In the short term terrestrial biota are likely to benefit from reduced environmental stresses, but in the long run the colonization of the region by lower latitude species with greater competitive ability will become increasingly important and can lead to large-scale changes in biological composition and trophic complexity in some existing Antarctic terrestrial ecosystems. Moreover, the recent dynamic climate changes combined with human activities in the Antarctic region might modify the status of several alien species which have hitherto been considered transient or persistent and could, therefore, become naturalized and threaten the native communities on a larger scale than today, or influence the status of naturalized species.
Brachiopods from the Chlamys Ledge Member, uppermost part of the Polonez Cove Formation (Oligocene), of King George Island, West Antarctica are represented by the undeterminable Rhynchonellida, one short-looped terebratulide Liothyrella Thomson, and two long-looped terebratellidines: Rhizothyris Thomson and Terebratelloidea gen. et sp. indet. Liothyrella is a well known genus in the Cenozoic strata and Recent waters of the Southern Hemisphere, while Rhizothyris is noted for the second time in the Antarctic region. This is the first record of brachiopods from the Chlamys Ledge Member.
To subscribe to the magazine enter the email address:
*Fields marked with an asterisk are mandatory to be filled in and checked. To Subscribe to the journal you must agree to the processing of personal data.