Polar Research (E-Journal)
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Low grade (greenschist facies) metamorphism in southern Prins Karls Forland, Svalbard
No full textThe pre-Carboniferous miogeosynclinal sedimentary and volcanic sequences of south-central Prins Karls Forland belong to a suite of rocks known as the Forland Complex. During early Palaeozoic diastrophism the Complex of Prins Karls Forland experienced predeformational, low grade metamorphism. A knowledge of the stratigraphy and structure of the region, together with an analysis of metamorphic mineral assemblages and reactions enable the conditions of metamorphism to be determined within certain limits. It is found that temperatures during metamorphism were between 400°C and 500°C, and pressures were about 6 kb. These conditions provide an estimate of palaeogeothermal gradient, consistent with observed mineralogies, of 18 to 21°C.km?1. In addition, compositional variations within mineral phases are found to be largely dependent upon bulk-rock chemistry, and are of limited use in determining grade changes
Vitrinite reflectance studies of coals and dispersed organic matter in Tertiary deposits in the Adventdalen area, Svalbard
No full textVitrinite reflectance measurements on coals and dispersed organic matter in Tertiary deposits in the Adventdalen area show that there is a continuous rank increase from 'sub-bituminous C (Ro = 0.40) at the top through 950 m to‘high volatile bituminous B’(Ro = 0.70) at the base. Rank of the economically important coal horizon at the base of the Tertiary shows regional variation ranging from 'sub-bituminous B’(Ro = 0.41) to Tiigh volatile bituminous A-B’(Ro = 0.78). It is concluded that 1.0 - 1.5 km of Tertiary deposits were eroded during the postorogene uplift of Svalbard, and the area of greatest sediment accumulation migrated eastwards during deposition
Petrology and geochemistry of Mesozoic dolerites from the Hinlopenstretet area, Svalbard
No full textMiddle Jurassic to Lower Cretaceous dolerite intrusions have a widespread occurrence throughout the Svalbard archipelago, especially in the Hinlopenstretet area. Petrographic and geochemical studies of ten samples collected near intrusion contacts from the Lomfjorden Sill and Wilhelmeya Island confirm that these dolerites are tholeiitic. Augite in these rocks is colorless to a distinct purplish-brown, which is unusual for this mineral in tholeiitic rocks. In spite of the high Ti02 contents (0.8–2.9 wt. %), which classify it as titania-rich augite to titanaugite, this augite is compositionally more similar to augite from other tholeiitic intrusions than to titanaugite from alkalic basalts. The samples are compositionally uniform (SiOa – 49.7–50.4 wt. %, MgO = 5.1–5.8 wt. %) and are characterized by high contents of Ti02 (3.3–3.6 wt. %) and opaque minerals (6–11 vol. %). The age and tholeiitic nature of these intrusions are consistent with the interpretation that they were associated with the extensional tectonics related to the generation of the Amerasia Basin
The Orustdalen Formation of Brøggerhalvøya, Svalbard: A fan delta complex of Dinantian/Namurian age
No full textThe Orustdalen Formation of Brøggerhalvaya is well exposed on two coastal sections and is 200–250 m thick. It consists dominantly of siliceous conglomerates and sandstones with subordinate shales and impure coal. One horizon low in the sequence yielded spores of uppermost Dinantian/lowermost Namurian age. Three sedimentary fades have been recognised. The fluvial channel facies (interbedded conglomerates and cross-stratified sandstones) are interpreted as braided stream deposits with flow directions to south and west. A shale facies, sometimes with drifted plant remains, is interpreted as overbank in origin. Highly quartzose, medium-to-coarse-grained, cross-stratified sandstones make up the reworked facies where palaeocurrents are bimodal or indicate movement to the NE. The Formation is thought to represent sediments shed from an early Carboniferous fault scarp eroding’a siliceous Lower Palaeozoic source terrain. The proximity of a nearby coastline led to the construction of fan deltas where fluvial deposits were reworked by waves and/or tides. Early diagenetic events include the local development of pyrite, kaolinite and calcite cements. Reddening’probably occurred during Middle Carboniferous times beneath an exposed land surface. Following burial, pressure solution and quartz cementation eliminated porosity at depths greater than 1000 m
Salterella rugosa (Early Cambrian: Agmata) on Nordaustlandet and Spitsbergen, Svalbard
No full textOccurrence of Salterella rugosa Billings on Nordaustlandet, Svalbard, is reported for the first time. The rocks that produced these fossils belong to the upper part of the Kapp Sparre Formation. This unit can be correlated with the Oslobreen Dolomite in Ny Friesland (Spitsbergen, Svalbard) from which the same species has been reported earlier; these fossils have not been illustrated previously. In both areas many specimens are poorly preserved, and it is becoming increasingly evident that the difference between Salterella and Volborthella simply may be the result of loss of the outer shell in the Volborthella
Radiocarbon dated raised beaches and glacial history of the northern coast of Spitsbergen, Svalbard
No full textRaised beaches, glacial erratics, glacial striae and ice marginal features along the north coast of Spitsbergen have been studied. Two series of raised beaches occur in the area bordering the outer part of Woodfjorden. The lower marine limit has an altitude of approximately 40 m and is close to 11,000 years in age. The upper marine limit is at 80 m above sea level and predates 40,000 years B.P. Emergence between 11,000 and 10,000 years ago took place at a rate exceeding 2 m/century, and approximately one-half of the total emergence took place during this interval. Three main directions of glacier ice movement are recorded, and marginal features from the Late Weichselian maximum glaciation occur on both sides of Liefdefjorden. Sediment cores from six shallow lakes on Reinsdyrflya show extremely slow rates of sedimentation and low organic production. The maximum sediment thickness encountered was 143 cm (Lake F, at 35 m above sea level). No radiocarbon dates have been obtained from these lakes. The Younger Dryas (11,000 to 10,000 years B.P.) seems to be a period of deglaciation. The deglaciation on the northern coast of Spitsbergen predates the final deglaciation in a number of other Arctic regions. Mytilus edulis immigrated to the area about 9400 years ago or earlier, indicating a warm early Holocene climate on the north coast of Spitsbergen
Discovery of thermal springs in the Raudfjellet region, SW Spitsbergen
No full textTwo thermal springs were discovered in the Raudfjellet region in Spitsbergen. They had a total discharge of about 0.1 m3/sec and were found in metamorphic carbonate rocks on bare ground under the eastern part of Torellbreen. Water with temperatures between 12.3 and 6.5°C caused thermoerosive phenomena to take place at the end of the eastern Torellbreen snout and formed an ice sheet covering the ground after cooling and freezing
Lower permian palaeoaplysinid bioherms and associated sediments from central Spitsbergen
No full textBioherms found in the Lower Permian Tyrrellfjellet Member of Central Spitsbergen contain bindstones produced by the ?hydrozoan taxon Palaeoaplysina. We briefly describe the bioherms’stratigraphical and environmental setting and note their development on hardground surfaces. The association of these structures with bituminous limestones is interesting in view of the petroleum resources of similar buildups in the USSR