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1.
Seismic facies and architecture of ice-contact submarine fans in high-relief fjords, Troms, Northern Norway 总被引：1，自引：0，他引：1
ASTRID LYSÅ TORE O. VORREN 《Boreas: An International Journal of Quaternary Research》1997,26(4):309-328
During the Late Weichselian, large marginal moraines were deposited in the Norwegian fjords. In Troms County these features are termed the Skarpnes and Tromsø-Lyngen moraines, respectively, and have been mapped from land into the marine environment where they were formed as ice-contact submarine fans. High-resolution seismic data from several fjords have been studied and reveal a typical sediment thickness of 150–320 m for these ice-contact systems. All of the ice-contact submarine fans were formed under similar climatic conditions, but display wide variation in geometry, architecture and seismic pattern. This variation is related to differences in sediment supply, the nature of the subsurface of the fan (e.g. position of thresholds), basin geometry and basin depth. Based on interpretation of the different seismic facies and the architecture of the fans, former ice-front positions have been suggested and a model has been presented for the formation of different types of ice-contact submarine fans dependent upon variation in local basin condition. 相似文献
2.
The distributional patterns of Barents Sea harp seals (Phoca groenlandica) throughout the year are presented based on existing literature and recent Norwegian and Russian field observations. The harp seals breed in February-March in the White Sea. Moulting occurs during April to June in the White Sea and southern Barents Sea. Feeding.behaviour is closely related to the configuration and localisation of the drifting sea-ice during summer and autumn (June-October) when the seals follow the receding ice edge, retiring gradually northwards and northeastwards in the Barents Sea. The southward movement of the population in autumn probably takes place in November prior to the advance of the ice edge, and is likely related to food-search. Apparently, most Barents Sea harp seals seems to concentrate at the southern end of their range in winter and spring. 相似文献
3.
Pyritization of tubes and burrows from Late Pleistocene continental shelf sediments off North Norway 总被引：1，自引：0，他引：1
Four different types of pyritized tubes and three types of pyritized burrow fillings are described from Pleistocene glaciomarine sediments in Andfjorden, northern Norway. The tubes and burrows probably originated from tubicolous and burrowing polychaetes respectively. The decomposition of the organic matter in the tubes and burrows created a reducing micro-environment favouring precipitation of pyrite. By comparison with Holocene tubes from marine sediments in Andfjorden and FugloSyfjorden, it is seen that pyritization commenced with isolated spherules. These spherules with incipient pyrite crystals and framboids were formed mainly on the inner wall of the tube. Presence of a monosulphide in the Holocene Fugløyfjorden material suggests that the pyritization process has reached a later phase; the final result would be a completely pyritized trace fossil. It is shown that single pyrite crystals (octahedra) generally attain greater size in the burrow fillings than in the tubes. The microstructure found in some of the pyritized tubes is interpreted as a reflection of the microstructure in the original wall. Finally, the implications for the depositional environment in Pleistocene in Andfjorden is investigated with reference to the benthic skeletal macrofaunal assemblage in the sequence. The pyritized trace fossils occur frequently in an opportunistic assemblage from a period (c. 14,000–13,000 yr BP) characterized by some oxygen deficiency. Later (13,000–10,000 yr BP) they play a minor role in an established assemblage under improved oxygen conditions. 相似文献
4.
KAI ROGER FLØISTAD JAN SVERRE LABERG TORE O. VORREN 《Boreas: An International Journal of Quaternary Research》2009,38(3):610-619
The sea-floor morphology of two pronounced across-fjord bedrock thresholds located at the mouths of Ofotfjorden and Tysfjorden, northern Norway, has been analysed based on swath bathymetry and seismic data. The Younger Dryas ice front was located here during the recession of one of the large palaeo-ice streams of the Fennoscandian Ice Sheet. The thresholds are several kilometres long and wide, rising to several hundred metres above the adjacent sea floor, and the slopes are steep, up to 25°. The Ofotfjorden threshold is draped by acoustically discontinuous to chaotic sediments partly infilling the bedrock relief. A pattern of well-developed, subglacial bedforms (e.g. crag-and-tail formations, drumlins and glacial lineations) on top of both thresholds suggests fast-flowing ice. A series of smaller transverse ridges is identified on both thresholds and probably records ice-front oscillations during the final deglaciation. The distal parts of the sediments have been remobilized by slides that occurred after glacial retreat from the thresholds. Earthquake activity due to the isostatic rebound following ice retreat from this area was the most likely triggering mechanism for the slides. The location of the ice front on a prominent bedrock threshold indicates that the basin configuration was important in locating the maximum position of the climatically induced re-advance, i.e. a topographic control on the maximum Younger Dryas position in the Ofotfjorden and Tysfjorden area is suggested. 相似文献
5.
MORTEN HALD TORE O. VORREN 《Boreas: An International Journal of Quaternary Research》1984,13(2):133-154
Based on studies of gravity cores from two transverse troughs on the shelf and earlier investigations, the surface sediments are divided into three main facies: bouldery and pebbly sand on the banks and the shelf break; sand on the flanks and outer parts of the troughs and sandy mud in the inner parts of the troughs. Besides a depth control, the distribution must have been influenced by relatively rapidly moving bottom currents in the outer parts of the troughs. The distribution and composition of the modern benthic foraminiferal fauna (e.g. C. lobatulus/T. angulosa in the outer reaches and C. obtusalBolivina spp. in the inner reaches) is mainly controlled by the bottom current regime and sediments. The planktic fauna dominated by N. pachyderma (R) correlates well with the winter surface temperatures. The stratigraphi-cal analysis shows that the 10,000–9,600 years B.P. period experienced high rates of deposition probably due to meltwater runoff from the continental ice sheet. At ca. 9,700 B.P. a minimum in the production of N. pachyderma (R) indicates a temporary cooling of the surface water. During the 9,600–7,800 B.P. period the rate of deposition was reduced. At the end of this period the foraminiferal fauna changed towards one like the modern fauna, reflecting improving ecological conditions. At ca. 7,800 B.P. the sediments became coarser due to reduced input of detrital sediments and an increased production of sand-sized biogenic material. Since then the shelf environment has been fairly stable up to the present time. 相似文献
6.
Lithologic, petrographic and paleontologic data for the various areas of late Silurian (?) and early Devonian grey-green sandstones (greywackes) in the Liefdefjord area of northern Spitsbergen are evaluated. A number of new localities with fossil fauna have been detected in these sandstones, both to the north and south of Liefdcfjordcn. It is shown that vertebrate and invertebrate fossils occur at lower levels than hitherto believed. Differences in the amounts of plagioclase and potash feldspar in the sandstones north and south of the fjord, as well as the finds of fossils, suggest that the Siktefjellet Sandstone is restricted to the type area north of Liefdefjorden. The grey-green sandstones south of Liefdefjorden are correlated with the Andreebrecn Sandstone Formation of the Red Bay Group. 相似文献
7.
TORE O. VORREN ARVID ELVSBORG 《Boreas: An International Journal of Quaternary Research》1979,8(2):247-253
The present knowledge of the Late Weichselian marginal moraines and paleoenvironment from the coastal and shelf areas of Troms and west Finnmark is reviewed. Diverse opinions exist regarding the position and age of the marginal moraines in the offshore areas. 相似文献
8.
TORE GJELSVIK 《Polar research》1991,9(2):141-154
The Siktefjcllet Group of late Silurian or early Devonian age. consisting of the Lilljeborgfjellet Conglomerate and the overlying Siktefjcllet Sandstone, is generally accepted as the oldest part of the Old Red Sandstone in Spitsbergen. Most of the clasts of the conglomerate are only slightly rounded and consist of lithologies typical for the underlying basement. A minor component of quartz porphyry clasts is present; these are well-rounded, indicating a longer transport. The provenance of the quartz porphyry clasts is discussed in relation to the known outcrops of quartz porphyry in Svalbard, one occurring in the neighbourhood of the conglomerate, the other ones far away. The quartz porphyry in close proximity is younger than the Lilljeborgfjellet Conglomerate and therefore not a possible source rock. A close petrographic and geochemical comparison with the quartz porphyries at three localities in Nordaustlandet (150-200 km in easterly direction and of probable Grenvillian age) is presented showing many similarities, but enough differences to question their interrelationship. The porphyries of the Hornsund area (300 km in southerly direction and also of probable Grenvillian age) are found to be chemically and pctrographically distinctly different from the Lilljeborgfjellet clast porphyry. Metarhyolite reported from the Planclfjclla and Har-kerbreen Groups in Ny Fricsland are not comparable with the clast porphyry. As no unquestionable source rock among the quartz porphyries is known in outcrop, the possibility of a hidden or completely eroded parent rock is considered. 相似文献
9.
TORE PASSE 《Boreas: An International Journal of Quaternary Research》1998,27(1):69-80
A non-uniform glacio-isostatic uplift can result in differential uplift for different parts of a lake. If the lake outlet is situated in the area of the greatest rate of uplift, then remote parts of the lake will be continuously transgressed. Ancient lake levels can be estimated by dating transgressed peat at different depths in such lakes. Four lakes in southern Sweden have been investigated using this method and the course of the glacio-isostatic uplift has been determined empirically. The investigation shows that the difference in uplift between the outlet and the sampling site can be expressed as an arctan function relating the difference in uplift over time to: half of the difference of the total uplift between the outlet and the sampling site, the time for the maximal rate of the uplift and a declining factor. 相似文献
10.
A total of 138 walruses ( Odobenus rosmarus rosmarus ), including 21 cow/calf pairs, were observed during a ship-board survey in the southeastern Barents and Pechora seas 5-17 February 1993. The observations confirm these areas as wintering and nursery grounds for the species. 相似文献