Structural development along the Billefjorden Fault Zone in the area between Kjellströmdalen and Adventdalen/Sassendalen, central Spitsbergen

The Billefjorden Fault Zone represents a major lineament on Spitsbergen with a history of tectonic activity going back into the Devonian and possibly earlier. Recent structural, sedimcntological and stratigraphical investigations indicate that most of the stratigraphic thickness variations within the Mesozoic strata along the Billefjorden Fault Zone south of Isfjordcn are due to Tertiary compressional tectonics related to the transpressive Eocene West-Spitsbergen Orogeny. No convincing evidence of distinct Mesozoic extensional events, as suggested by previous workers, has been recognized. Tertiary compressional tectonics are characterized by a combined thin-skinned/thick-skinned structural style. Decollement zones arc recognized in the Triassic Sassendalen Group (tower Décollement Zone) and in the Jurassic/Cretaceous Janusfjellet Subgroup (Upper Décollement Zone). East-vergent folding and reverse faulting associated with these decollement' zones have resulted in the development of compressional structures, of which the major arc the Skolten and Tronfjellct Anticlines and the Advcntelva Duplex. Movements on one or more high angle east-dipping reverse faults in the pre-Mesozoic basement have resulted in the development of the Juvdalskampcn Monocline, and are responsible for out-of-sequence thrusting and thinning of the Mesozoic sequence across the Billefjorden Fault Zone. Preliminary shortening calculations indicate an eastward displacement of minimum 3-4 km, possibly as much as 10 km for the Lower Cretaceous and younger rocks across the Billefjorden Fault Zone.     

The retreat of the Barents Sea Ice Sheet on the western Svalbard margin

The deglaciation of the continental shelf to the west of Spitsbergen and the main fjord, Isfjorden. is discussed based on sub-bottom seismic records and scdirncnt cores. The sea lloor on the shelf to the west of Isfjorden is underlain by less than 2 m of glaciomarine sediments over a firm diamicton interpreted as till. In central Isfjordcn up to 10 m of deglaciation sediments were recorded, whereas in cores from the innermost tributary, Billefjorden, less than a meter of ice proximal sediments was recognized between the till and the 'normal' Holocene marine sediments. We conclude that the Barents Sea Ice Sheet terminated along the shelf break during the Late Weichselian glacial maximum. Radiocarbon dates from thc glaciomarine sediments above the till indicate a stepwise deglaciation. Apparently the ice front rctrcatcd from the outermost shelf around 14. 8 ka A dramatic increase in the flux of line-grained glaciomarine sediments around 13 ka is assumed to reflect increased melting and/or current activity due to a climatic warming. This second stage of deglaciation was intcrruptcd by a glacial readvance culminating on the mid-shelf area shortly after 12.4 ka. The glacial readvance, which is correlated with a simultaneous readvance of the Fennoscundian ice sheet along the western coast of Norway, is attributed to the so-called 'Older Dryas' cooling event in the North Atlantic region. Following this glacial readvance the outer part of Isljorden became rapidly deglaciated around 12.3 ka. During the Younger Dryas the inner fjord branches were occupied by large outlet glaciers and possibly the ice liont terminated far out in the main fjord. The remnants of the Harcnts Sea Ice Shcet melted quickly away as a response to the Holocene warming around 10 ka.     

An equation of state for biologically active lake sediments and its implications for interpretations of sediment data

The aim of this work is to link physical sediment parameters to biological parameters by an equation of state, which describes how the given variables interact in biologically active deposits from accumulation areas, i.e. lake areas where fine material is being continuously deposited. In the model the following parameters are utilized: sediment depth, rate of deposition, degree of compaction, bulk density, water content, net biotransport, upward biotransport, downward biotransport, and substrate decomposition. The equation of state has been empirically tested with data from Lake Ekoln and Lake Vänern, Sweden. The model enables determinations of age frequency distributions for arbitrary sediment layers, and it has been shown that, for example, the sediment layer 12-13 cm in Lake Ekoln has a median age of 15.3 years and that the deposits from the median year only constitutes about 15% of the total amount of material in this particular sediment layer. The spread due to bioturbation is considerable and the range at this sediment layer is 22 years. A mechanism to explain secondary lamination is introduced and discussed in the light of the results from the model.     

Breeding distribution and abundance of the great cormorant Phalacrocorax carbo carbo in Greenland

The Greenland population of the great cormorant Phalacrocorax carbo carbo numbers 2000–3000 pairs which breed in about 110 colonies distributed along a 1000 km long coastline in central and northern West Greenland. The number of colonies has increased and the breeding range has expanded in recent decades. These trends are believed to be related to a reduced hunting pressure. The number of nests per colony is smaller than in European colonies. The population is of particular conservation concern to Greenland because of its small size and presumed discrete status.     

Late-and postglacial environments in the northern Barents Sea west of Franz Josef Land

A lithological and micropaleontological study of three sediment cores from the western Franz Josef Land area, two of them AMS ^l4C dated, provides new data on the environmental evolution of the northern Barents Sea during and after the last deglaciation. Glacimarine conditions commenced in the deep Franz Victoria Trough by 13 kyr BP. and then presumably propagated into adjacent inter-island channels of Franz Josef Land. Pulses of Atlantic-derived water occurred during deglaciation and could have accelerated ice-sheet decay. Normal marine environments were established close to 10 kyr BP. Ameliorated conditions are recorded for the interval of approximately 9.5 to 5 kyr BP. After that, more severe environments existed probably associated with heavier sea-ice cover.     

The effects of oil and oil dispersants on the amphipod Gammarus oceanicus from Arctic waters

Amphipods of the species Gammarus oceanicus were exposed to water soluble fractions and water emulsions crude oil, the dispersants Finasol OSR-5 and Finasol OSR-12, and combinations of the oil and dispersants. Adding Finasol OSR-12 to the crude oil caused a reduction in the mortality of the amphipods compared with amphipods exposed to the water soluble fraction and the water emulsion of crude oil alone, probably due to a reduced mole fraction of toxic oil components in the mixture of oil and dispersant. Exposure to sublethal concentrations of water soluble fractions increased the respiratory rates of the amphipods in the majority of the exposed groups. The water soluble fractions slightly increased the concentrations of sodium in the haemolymph and in the whole organism. Some exposures gave a significant increase in the relative water content of the amphipods. The water soluble fractions probably increase the membrane permeability to water and ions, leading to an increased influx of water and sodium from the medium. The increased respiratory rates are likely to be due to a compensatory extrusion of sodium. Exposure to sublethal concentrations of water emulsions reduced the respiratory rates of the amphipods, probably due to oil droplets adhering to the gill membranes and thus causing a reduced rate of oxygen diffusion into the organisms. The majority of the exposures to water emulsions increased concentrations of sodium in the haemolymph as well as in whole organisms. Thus, sodium probably accumulates in the intracellular compartments because the sodium pumps are restricted by the reduced energy available. This is likely to lead to an osmotic swelling of cells. Reduced total free amino acid concentrations in these amphipods is ascribed to volume regulation of the swollen cells, and a reduced co-transport of sodium and free amino acids from the haemolymph to the intracellular compartments.