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1.
Four relative sea-level curves from Edgeøya and Barentsøya are constructed based on 81 radiocarbon age determinations on carefully selected and levelled samples in raised beaches, mostly driftwood embedded in beach gravel. All the dates, covering the period from the deglaciation to the present, are calibrated to calendar years, and the sea-level curves are defined by fitting the data with a least square regression curve. The dates are internally very consistent, and the results are some of the most precise sea-level curves from the Arctic.
The four curves are quite similar, and from the marine limit at 85-90 m a.s.l. they show a rapid emergence (ca 40 mm/year), formed about 11,000 cal yrs BP (∼10,00014 C yrs BP). A minimum rate of emergence close to 8000 cal years ago is explained by a decreased rate in isostatic uplift parallel with a sustained rate of eustatic sea-level rise. During the last 7000 cal years, the emergence rate has decreased linearly. The uplift rates have been slightly higher on southern Edgeøya than further north during the last 7000 years. By comparing the sea-level curves from Storøya (ca 270 km to the north) and Hopen (ca 150 km to the south), we suggest that a memory of an earlier and larger glacio-isostatic downwarping in the southern Barents Sea is detected in the sea-level curves from Hopen and southern Edgeøya. 相似文献
The four curves are quite similar, and from the marine limit at 85-90 m a.s.l. they show a rapid emergence (ca 40 mm/year), formed about 11,000 cal yrs BP (∼10,000
2.
LAURITZ SøMME 《Polar research》1986,4(2):231-233
Steveacarus evansi (Hunter) (Acari, Mesostigmata) and Friesea tilbrooki Wise (Collembola) are reported for the first time from Bouvetøya (54°25'S, 3°21'E). At present a total of four free-living species of Acari and three species of Collembola are known from this isolated island. 相似文献
3.
NILS ARE ØRITSLAND 《Polar research》1998,17(1):101-105
Two censuses made of the population of Svalbard reindeer on Edgeøya in 1983 and 1996 resulted in 1586 and 2434 individuals respectively. Together with data from earlier population surveys (1969-77), this indicates, numerically, a population growth during the period 1969-96. Because of the weaknesses in the different census methods used, we cannot conclude that in reality a population growth has taken place even though the numerical data is correct. Therefore an average population size of 1730 (± 451 SD) individuals for the period 1969-96 is suggested. Earlier estimates of vegetated area indicate that the present data corresponds to reindeer densities averaging 1.05 and ranging from 0.79 to 1.47 individuals/km2 . 相似文献
4.
The Triassic succession of Bjørnøya (200 m) comprises the Lower Triassic Urd Formation (65 m) of the Sassendalen Group, and the Middle and Upper Triassic Skuld Formation (135 m) of the Kapp Toscana Group. These units are separated by a condensed '.'Middle Triassic sequence represented by a phosphatic remainé conglomerate (0.2m).
The Urd Formation consists of grey to dark grey shales with yellow weathering dolomitic beds and nodules. Palynology indicates the oldest beds to be Diencrian; ammonoid faunas in the middle and upper part of the formation arc of Smithian age. The organic content (c. 1 %) includes kerogen of land and marine origin, reflecting a shallow marine depositional environment.
The Skuld Formation is dominated by grey shales with red weathering siderite nodules. There are minor coarsening upwards sequences; the highest bed exposed is a 20 m thick, very fine-grained sandstone. Palynomorphs indicate a late Ladinian age for the lower part of the formation, and macrofossils and palynomorphs indicate Ladinian to Carnian ages for the upper part. Sedimentary structures, a sparse marine fauna and microplankton indicate deposition in a shallow marine environment. The organic residues contain dominantly terrestrially derived kerogen. 相似文献
The Urd Formation consists of grey to dark grey shales with yellow weathering dolomitic beds and nodules. Palynology indicates the oldest beds to be Diencrian; ammonoid faunas in the middle and upper part of the formation arc of Smithian age. The organic content (c. 1 %) includes kerogen of land and marine origin, reflecting a shallow marine depositional environment.
The Skuld Formation is dominated by grey shales with red weathering siderite nodules. There are minor coarsening upwards sequences; the highest bed exposed is a 20 m thick, very fine-grained sandstone. Palynomorphs indicate a late Ladinian age for the lower part of the formation, and macrofossils and palynomorphs indicate Ladinian to Carnian ages for the upper part. Sedimentary structures, a sparse marine fauna and microplankton indicate deposition in a shallow marine environment. The organic residues contain dominantly terrestrially derived kerogen. 相似文献
5.
Bjørnøya has a very thin cover of unconsolidated Quaternary sediments. Glacial erratics of local origin are spread throughout the lowland areas, and glacial striae indicate glacial movement which was centred middle of the island. No traces of the Barents Sea ice sheet have been observed on Bjørnøya, nor has there been any postglacial emergence of the island. Lake cores date the deglaciation of the lowlands to ca 10,000 BP, and peat deposits on high mountains show that these were deglaciated before 8700 bp. 相似文献
6.
ÓLAFUR INGÓLFSSON FINNBOGI RÖGNVALDSSON HELENE BERGSTEN LARS HEDENÄS GEOFFREY LEMDAHL JUAN M. LIRIO HANS PETTER SEJRUP 《Polar research》1995,14(2):123-139
On western Kongsøya, Svalbard, three coarsening-upwards sequences of marine to littoral sediments, separated by tills, are recognised in sections at ca 50-92 m above present sea level. These sequences show major glaciations in the northern Barents Sea, resulting in substantial glacioisostatic downpressing of Kongsøya. Till fabrics indicate ice movements controlled by the local topography, while glaciotectonic deformations suggest that ice moved from an ice divide northeast of Kongsøya. independent of the local topography. The stratigraphical evidences show two pre-Holocene ice-free periods, when the climate was similar to or slightly warmer than at present. The age of these periods is not clear. It is suggested that the elder ice free interval is older than isotope stage 5e. The younger ice free interval could be of Eemian or Early Weichselian age. The uppermost succession of sublittoral-littoral sediments is of early Holocene age. It relates to the high (≥100 m) postglacial marine limit, dated to approximately 10,000 bp. 相似文献
7.
Early Holocene, near-shore marine sediments from Visdalen, Edgeøya, eastern Svalbard contain locally abundant allochthonous remains of land plants, notably bryophytes. Wetland species indicative of mineral rich and calcareous soils are frequent, but upland plants are also well represented. The fossil assemblages are indicative of ecological and climatic conditions similar to those on Edgeøya today. The sediments contain one of the first fossil beetles reported from Svalbard. Apparently, the modern flora of Svalbard was already established in the earliest Holocene, probably following immigration from northern Europe. A few Armeria scabra remains are believed to be derived from interglacial deposits. 相似文献
8.
PETRA LUDWIG 《Polar research》1991,9(1):65-76
The change from continental to marine conditions in the Middle Carboniferous on Brøggerhalvøya started at the end of the Bashkirian with short-term transgressive events at the top of the Brøggertinden Formation. Local basin subsidence was responsible for the pulsatory nature of the transgression. The establishment of a shallow marine carbonate-dominated environment is represented by the Moscovian Scheteligfjellet Member which overlies the post-Caledonian red beds of the Brøggertinden Formation. The Scheteligfjellet Member is the lowermost member of the Nordenskioldbreen Formation and shows distinct lateral facies variations. Three facies associations can be distinguished: lagoonal facies, shoal facies and open marine facies. The succeeding two members were deposited in subtidal areas of the carbonate platform. A basin subsidence event at the Carboniferous/Permian boundary was responsible for a short shift into deeper depositional environments during a time of worldwide regression. After this a continuous regression led to supratidal conditions at the top of the Nordenskioldbreen Formation. 相似文献
9.
An 18.5 m thick shale sequence of Norian-Rhaetian age is described from the Bohemanfiya-Syltoppen area (north of Isfjorden, central Spitsbergen). Lithological, petrographical and palynological analyses show that the sequence represents a marginal development of the lower part of the Wilhelmeya Formation. The depositional history at the Triassic-Jurassic transition is discussed in the light of this new evidence. The Wilhelmøya Formation was probably deposited during a weak marine transgression over an area of low relief. Low sediment supply and current and wave reworking of the sediments characterized the depositional conditions. 相似文献
10.
Terrace remnants close to the marine limit as well as two separate moraine ridges are observed in front of the glacier Albrechtbreen. The stacking of marine sediments from an original elevation of ca. 60–80 m a.s.l. into the Little Ice Age Moraine gives evidence for a considerably smaller glacier following the early Holocene deglaciation compared to that of the present. The outer moraine is composed of glacial diamicton. Radiocarbon datings of whale ribs, shell fragments and a log taken from sediment in front of Albrechtbreen indicate that the initial deglaciation occurred before 9, 400 B.P. and that the outer moraine was formed during a younger Holocene glacial advance. Lithological differences between the two moraine ridges suggest that the first ice advance occurred during a period with limited permafrost, whereas permafrost was more extensive during the Little Ice Age. 相似文献
11.
BARBARA WOHLFARTH GEOFFREY LEMDAHL SIV OLSSON THOMAS PERSSON IAN SNOWBALL JONAS ISING VIV JONES 《Polar research》1995,14(2):253-275
Bjørnøya, a small (178 km2 ) island situated between the mainland of Norway and southern Spitsbergen, provides the opportunity for the reconstruction of early Holocene terrestrial and limnic palaeoenvironments in the southwestern Barents Sea. The AMS 14 C dating technique, geochemical, mineral magnetic, micro and macrofossil analyses were applied to sediments recovered from lake Stevatnet and the results are interpreted in terms of palaeoenvironmental conditions between 9800 and 8300 14 C bp. After the disappearance of local glaciers before ca 980014 C BP, the lake productivity increased rapidly at the same time as pioneer plant communities developed on soils which gradually became more stable. Insect data indicates that strong seasonal contrasts with mean July temperatures around 9°C and mean January temperatures around −12°C prevailed between 9500 and 8300 14 C BP. These high summer temperatures, possibly as much as 4-5°C higher than the present, favoured the development of a flora including Dryas and Angelica cf. archangelica . The enhanced freeze/thaw processes led to an increased erosion of minerogenic and organic material. After 8000 14 C BP the temperatures may have gradually declined. The environmental reconstruction derived from our data set supports the conceptual insolation model which proposes maximum Holocene seasonality for the Northern Hemisphere at ca 9000 14 C BP. 相似文献
12.
The Present foraminiferal distribution (live + dead) in Freemansundet between Barentsøya and Edgeøya, Svalbard, has been compared with assemblages in raised marine Holocene deposits in Guldalen on Edgeeya. Four distinct foraminiferal assemblages were identified in Freemansundet, the Elphidium excavatum-Cassidulina reniforme assemblage, the Elphidium hallandense assemblage, the Cibicides lobatulus assemblage and the Elphidium incertum-Haynesina orbiculare assemblage. Four assemblage zones (Zones A-D) have been established in the glaciomarine to marine sediment sequence in Guldalen. Only two of the recent fauna! types were represented here. The Elphidium excavatum-Cassidulina reniforme assemblage, which reflects a proximal glacier environment, was found in the lowermost Zone A (the Elphidium excavatum Zone) and in Zone C (the Elphidium excavatum-Cassidulina reniforme Zone) in the Guldalen stratigraphy; the Elphidium incertum-Haynesina orbiculare assemblage, which reflects ameliorated shallow water conditions, was found in the uppermost Zone D in Guldalen. The marine sequence in Guldalen represents a relatively short period of time during the Early Holocene (ca 9700 to 8300 BP). The succession of the foraminiferal assemblages suggests that the deglaciation was interrupted by a cold period with glacial stagnation just after 9600 bp (Zone B. the Astrononion gallowayi-Nonionellina labradorica Zone). 相似文献
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14.
DAVID HUDDART MATTHEW R. BENNETT MICHAEL J. HAMBREY NEIL F. GLASSER KEVIN CRAWFORD 《Polar research》1998,17(1):61-70
Well-rounded gravels are described from moraine-mound complexes, diamicton forefields and modern englacial thrusts at the margins of four glaciers on the northern side of Brøggerhalvøya, northwest Spitsbergen. Their shape charcteristics are compared with modern and fossil glacigenic, modern beach and Early Weichselian beach gravels from this peninsula. The best discriminators of the well-rounded gravels have been found to be the percentage-frequency roundness histograms, the roundness mid-point and roundness range diagrams and the sphericity-roundness plots. It is concluded that the gravels have been derived by englacial thrusting from Early Weichselian or last interglacial beaches in the inner parts of the fjord and in the low level cirques when sea level reached at least 50m a.s.l. and deposited the beach gravels. The discrimination between gravel in basal diamictons, proglacial outwash and modern beaches is difficult as the reworking has resulted in little particle shape change. The potential major problem caused by reworking in the glacial environment is emphasised. especially when clast shape comparisons from modern environments to older sediments are used. 相似文献
15.
Ingrid Anell Valentin Zuchuat Anna Daniela Rhnert Aleksandra Smyrak‐Sikora Simon Buckley Gareth Lord Harmon Maher Ivar Midtkandal Kei Ogata Snorre Olaussen Per T. Osmundsen Alvar Braathen 《Basin Research》2021,33(1):478-512
The study describes the depositional development and sediment partitioning in a prograding paralic Triassic succession. The deposits are associated with the advance of large prism‐scale clinoforms across a shallower platform area. Approaching the platform, the limited accommodation and associated relative higher rates of deposition generated straighter clinoforms with lower foreset angles. The vertical restriction across the platform is interpreted to have amplified the tidal signature. Sediment was redistributed from the coast into increasingly sandy delta‐front deposits, compared to offshore equivalents. The deposits comprise extensive compound dune fields of amalgamated and increasingly clean sandbodies up‐section. Rapid deposition of significant amounts of sand led to differential subsidence and growth‐faulting in the delta front, with downthrown fault blocks further amplifying the tidal energy through funnelling. A mixed‐energy environment created along‐strike variability along the delta front with sedimentation governing process‐regime. Areas of lower sedimentation were reworked by wave and storm‐action, whereas high sedimentation rates preserved fluvially dominated mouth bars. A major transgression, however, favoured tidally dominated deposits also in these areas, attributed to increasing rugosity of the coastline. Formation of an extensive subaqueous platform between the coast and delta front dampened incoming wave energy, and tidally dominated deposits dominate the near‐shore successions. Meanwhile formation of wave‐built sand‐bars atop the platform attest to continued wave influence. The strong tidal regime led to the development of a heterolithic near‐shore tidally dominated channel system, and sandier fluvial channels up‐river. The highly meandering tidal channels incising the subaqueous platform form kilometre wide successions of inclined heterolithic stratification. The fluvially dominated channels which govern deposition on the delta plain are narrower and slightly less deep, straighter, generally symmetric and filled with cleaner sands. This study provides important insight into tidal amplification and sand redistribution during shallowing on a wide shelf, along with along‐strike process‐regime variability resulting from variations in sediment influx. 相似文献
16.
17.
we have obtained one year of measurements from a subsurface instrumented mooring carrying two current meters and one bottom pressure recorder in the strait between Nordaustlandet and Kvitøya in the northeastern Svalbard archipelago. The observations show a mixed tide with typical amplitudes 0.4 db and 10cm sec−1 . The semidiurnal tide is characterized by a progressive wave propagating toward the south. together with a cross-channel baroclinic mode. The annual average (non-tidal) current is less than 2cm sec−1 toward the north-east, suggesting that the transport into the Arctic Ocean is approximately 0.2 × 106 m3 s−1 . 相似文献
18.
The upper Bashkirian-Moscovian Kapp KIre Formation is well-exposed in coastal cliff sections along the west coast of Bjørnøya, Svalbard. It is composed of stacked cycles of nixed siliciclastics and carbonates in the lower Bogevika Member and of cyclic shelf carbonates in the overlying Efuglvika Member. The uppermost Kobbebukta Member consists of shelf carbonates and syntectonic conglomerates and sandy turbidites. The shift in cycle types reflects an overall transgression of the region during the Moscovian combined with renewed tectonic activity and uplift of eastern Bjørnøya during the late Moscovian. Twelve carbonate facies and 6 siliciclastic facies are distinguished. The carbonate facies range from intertidal dolomitic mudstones with pseudomorphs after gypsum to subwavebase, intensely bioturbated wackestones. Most carbonates are deeper subtidal facies and shallow marine carbonate facies are only common in the transgressive part of mixed siliciclastic-carbonate cycles of the Bogevika Member. Incorporating the effects of high amplitude, high frequency glacioeustacy and active extensional tectonism, a dynamic model is developed to explain the spatial variability of facies observed within the Kapp Kke Formation. Observations from Bjørnøya are placed within the context of the regional structural and stratigraphic framework so that significance of the study to ongoing exploration efforts in the Barents Sea can be evaluated. Most important, our observations suggest that dolomitized, porous carbonate buildups are most likely to be found in the upper Moscovian succession in areas where accommodation space increased temporarily due to local tectonism. 相似文献
19.
《Basin Research》2018,30(5):1042-1073
The Late Triassic outcrops on southern Edgeøya, East Svalbard, allow a multiscale study of syn‐sedimentary listric growth faults located in the prodelta region of a regional prograding system. At least three hierarchical orders of growth faults have been recognized, each showing different deformation mechanisms, styles and stratigraphic locations of the associated detachment interval. The faults, characterized by mutually influencing deformation envelopes over space‐time, generally show SW‐ to SE‐dipping directions, indicating a counter‐regional trend with respect to the inferred W‐NW directed progradation of the associated delta system. The down‐dip movement is accommodated by polyphase deformation, with the different fault architectural elements recording a time‐dependent transition from fluidal‐hydroplastic to ductile‐brittle deformation, which is also conceptually scale‐dependent, from the smaller‐ (3rd order) to the larger‐scale (1st order) end‐member faults respectively. A shift from distributed strain to strain localization towards the fault cores is observed at the meso to microscale (<1 mm), and in the variation in petrophysical parameters of the litho‐structural facies across and along the fault envelope, with bulk porosity, density, pore size and microcrack intensity varying accordingly to deformation and reworking intensity of inherited structural fabrics. The second‐ and third‐order listric fault nucleation points appear to be located above blind fault tip‐related monoclines involving cemented organic shales. Close to planar, through‐going, first‐order faults cut across this boundary, eventually connecting with other favourable lower‐hierarchy fault to create seismic‐scale fault zones similar to those imaged in the nearby offshore areas. The inferred large‐scale driving mechanisms for the first‐order faults are related to the combined effect of tectonic reactivation of deeper Palaeozoic structures in a far field stress regime due to the Uralide orogeny, and differential compaction associated with increased sand sedimentary input in a fine‐grained, water‐saturated, low‐accommodation, prodeltaic depositional environment. In synergy to this large‐scale picture, small‐scale causative factors favouring second‐ and third‐order faulting seem to be related to mechanical‐rheological instabilities related to localized shallow diagenesis and liquidization fronts. 相似文献
20.
The study of a subfossil peat from the northwestern part of Edgeøya (Svalbard) enabled a reconstruction of the changes in the testate amoebae communities from c. 5000 BP to c. 3800 BP to be made. Two stratigraphical zones are recognized. The ecological interpretation of these sequences revealed rather humid and unstable hydrological conditions at the bog surface in the oldest zone, which presumably lasted until about 4500-4300 BP. The communities in the upper zone indicated a more stable and drier environment. 相似文献