Neotectonics, sea-level changes and biological evolution in the Fennoscandian Border Zone of the southern Kattegat Sea   总被引：1，自引：0，他引：1  

JØRN BO JENSEN  KAJ STRAND PETERSEN  PETER KONRADI  ANTOON KUIJPERS  OLE BENNIKE  WOLFRAM LEMKE  RUDOLF ENDLER 《Boreas: An International Journal of Quaternary Research》2002,31(2):133-150

Shallow seismic data and vibrocore information, sequence stratigraphic and faunal evidence have been used for documentation of Late Weichselian reactivation of faulting in the south central Kattegat, southern Scandinavia. The study area is situated on the Fennoscandian Border Zone, where tectonic activity has been recurrent since Early Palaeozoic time and still occurs, as shown by present earthquake activity. New data from the area south of the island of Anholt show that after deglaciation fast isostatic rebound resulted in reactivation of a NW-SE striking normal fault system. This tectonic episode is dated to a period starting shortly before 15.0 cal. ka BP and ending around 13.5 cal. ka BP, after regression had already reached a level of about 30 m b.s.l. The vertical displacement associated with the faulting was in the order of 20 m. More generally, the results support the previously reported late Weichselian sea-level highstand, which was followed by forced regression until the eustatic sea-level rise surpassed the rate of glacio-isostatic rebound in early Preboreal. Our findings further imply that drainage of the Baltic Ice Lake through the Øresund at c. 15 cal. ka BP (Bergsten & Nordberg 1992) may have been triggered by tectonic activity in this region.  相似文献   

Late- and postglacial history of the Great Belt, Denmark   总被引：3，自引：0，他引：3  

OLE BENNIKE  JØRN BO JENSEN  WOLFRAM LEMKE  ANTOON KUIJPERS  STEEN LOMHOLT 《Boreas: An International Journal of Quaternary Research》2004,33(1):18-33

On the basis of shallow seismic records, vibrocoring, macrofossil analyses and AMS radiocarbon-dating, five stratigraphical units have been distinguished from the deepest parts of the central Great Belt (Storebælt) in southern Scandinavia. Widespread glacial deposits are followed by two lateglacial units confined to deeply incised channels and separated by an erosional boundary. Lateglacial Unit I dates from the time interval from the last deglaciation to the Allerød; lateglacial Unit II is of Younger Dryas age. Early Holocene deposits show a development from river deposits and lake-shore deposits to large lake deposits, corresponding to a rising shore level. Lake deposits are found up to 20 m below the sea floor, and the lake extended over some 200–300 km2. The early Holocene freshwater deposits are dated to the time interval c. 10900 to c. 8800 cal. yr BP and the oldest shells of marine molluscs from the Great Belt are dated to c. 8100 cal. yr BP.  相似文献   

Little Ice Age advance and retreat sediment budgets for an outlet glacier in western Norway     

VALENTIN BURKI  LOUISE HANSEN  OLA FREDIN  THORBJØRN A. ANDERSEN  ACHIM A. BEYLICH  MICHEL JABOYEDOFF  EILIV LARSEN  JAN‐FREDERIK TØNNESEN 《Boreas: An International Journal of Quaternary Research》2010,39(3):551-566

Burki, V., Hansen, L., Fredin, O., Andersen, T. A., Beylich, A. A., Jaboyedoff, M., Larsen, E. & Tønnesen, J.‐ F. 2009: Little Ice Age advance and retreat sediment budgets for an outlet glacier in western Norway. Boreas, Vol. 39, pp. 551–566. 10.1111/j.1502‐3885.2009.00133.x. ISSN 0300‐9483 Bødalsbreen is an outlet glacier of the Jostedalsbreen Ice Field in western Norway. Nine moraine ridges formed during and after the maximum extent of the Little Ice Age (LIA). The stratigraphy of proglacial sediments in the Bødalen basin inside the LIA moraines is examined, and corresponding sediment volumes are calculated based on georadar surveys and seismic profiling. The total erosion rates (e_tot) by the glacier are determined for the periods AD 1650–1930 and AD 1930–2005 as 0.8 ± 0.4 mm/yr and 0.7 ± 0.3 mm/yr, respectively. These rates are based on the total amount of sediment delivered to the glacier margin. The values are almost one order of magnitude higher than total erosion rates previously calculated for Norwegian glaciers. This is explained by the large amount of pre‐existing sediment that was recycled by Bødalsbreen. Thus, the total erosion rate must be considered as a composite of eroded bedrock and of removed pre‐existing sediments. The total erosion rate is likely to vary with time owing to a decreasing volume of easily erodible, unconsolidated sediment and till under the glacier. A slight increase in the subglacial bedrock erosion is expected owing to the gradually increasing bedrock surface area exposed to subglacial erosion.  相似文献   

COOLING RATES, SKY VIEW FACTORS AND THE DEVELOPMENT OF INTRA-URBAN AIR TEMPERATURE DIFFERENCES     

BJÖRN HOLMER  SOFIA THORSSON  INGEGÄRD ELIASSON 《Geografiska Annaler: Series A, Physical Geography》2007,89(4):237-248

Intra‐urban cooling rates were monitored for a year in the centre of Göteborg on the Swedish west coast. Five sites with different building geometry ‐ from dense canyon to open space ‐ within a radius of 300 m were analysed. Results showed two modes of cooling during the night. In the first mode, the cooling was site‐dependent ‐the open space cooled the most and the dense canyon the least. In the second mode, which began about 3–4 hours after sunset, all sites cooled at the same rate. Our hypothesis is that in the early part of the evening both radiative divergence and sensible heat dominate the cooling. However, as the evening progresses, a spatially homogeneous inversion is established which controls the radiative cooling, making the cooling independent of both surface geometry and surface type. From April to November the sites cooled rapidly around sunset and the cooling slowly decreased during the rest of the night. However, between December and March, the cooling was less intense, with an almost constant rate during the entire night. It has been suggested that this might be the result of the draining of stored solar heat during the summer and a continuous flux of anthropogenic heating during the winter.  相似文献   

Foraminiferal stratigraphy of raised marine deposits, representing isotope stage 5, Prins Karls Forland, western Svalbard     

HELENE BERGSTEN  TORBJÖRN ANDERSSON  ÓLAFUR INGÓLFSSON 《Polar research》1998,17(1):81-91

Two raised marine sequences from Prins Karls Forland, western Svalbard, interpreted to have been deposited during part of isotope substage 5e (Eemian) and substage 5a, were studied for foraminifera content. Time constraints are given by ¹⁴C ages, infrared stimulated luminescence age estimates and amino acid ratios in subfossil marine molluscs. A diamicton (unit B) separates the two marine sequences and reflects an advancement of local glaciers sometime late in isotope stage 5. The two marine sequences contain diverse benthic foraminiferal faunas, indicating periods of a relatively warm and seasonally ice-free marine shelf environment. Compared to the lowermost sequence (unit A), the upper marine sequence (unit C) seems to reflect a more shallow environment that could have resulted from the global lowering of the sea level towards the end of isotope stage 5. Our results further emphasise the problem of biostratigraphic distinction between interglacial and interstadial deposits at high latitudes, with temperature conditions for substage 5a close to those of substage 5e and present conditions.  相似文献   

Eemian and Weichselian stratigraphy in South Sweden   总被引：1，自引：0，他引：1  

BJÖRN E. BERGLUND  ERIK LAGERLUND 《Boreas: An International Journal of Quaternary Research》1981,10(4):323-362.

The stratigraphy of Pleistocene sequences within three main areas of the province of Skane, South Sweden, is discussed. The traditional stratigraphy is revised. New lithostratigraphic units are deficned and named according to international stratigraphic terminology. Lithostratigraphical correaltions are based on sedimentological development and palaeoenvironmental changes. Organic beds are correlated with the Eemain interglacial and some of the Early and Middle Weichselian interstadials. The chronostratigraphic key site, Stenberget, is described in greater detail. Stratrigraphy and palaeoenvironment are summarized in a scheme indicating that South Sweden was glaciated only during the period 21,000–13,000 B.P.  相似文献   

The subdivision of the Quaternary of Norden: a discussion     

JAN MANGERUD  BJÖRN E. BERGLUND 《Boreas: An International Journal of Quaternary Research》1978,7(3):179-181

The proposal for Quaternary stratigraphy of Norden published 1974 by Mangerud, Andersen, Berglund & Donner was discussed at a Nordie meeting 1978. On the basis of this discussion some recommendations are proposed here which deviate slightly from the 1974 proposal: (1) the term Flandrian should not be used in Norden until it is properly defined in the type area, (2) the Middle/Late Weichselian boundary should provisionally be defined as 25,000 ¹⁴C years B. P. In addition it was stated that there is an urgent need for complete subdivision of the Weichselian into a continuous chronozone sequence.  相似文献   

Late Weichselian and Holocene environments of lake Endletvatn, Andφya, northern Norway: as evidenced primarily by chemostratigraphical data     

KARL-DAG VORREN  TORBJ&#;RN ALM 《Boreas: An International Journal of Quaternary Research》1999,28(4):505-520

A 6.5 m long sediment succession (18.5-2.2 ka BP) from the northern sub-basin of lake Endletvatn was analysed lithologically, palynologically and chemically. The chemical analyses were performed at about 10 cm depth intervals for the following parameters: total organic C, N, P, Fe, Mn, Mg, Na, K, Ca and S, in addition to water content, dry density, and pH. Two main lithostratigraphical units can be distinguished, which also differ substantially in chemical characters. Five chemostratigraphical main units were distinguished. The two lowermost units 1-2 (18.5-12.9 ka BP) correspond to the lower lithostratigraphical main unit and are characterized by minerogenous sediments with low C and N, and high Fe, Mg and K. P is low, partly because of a scarcity of P in parent rocks. Chemostratigraphical unit 3 (12.9-9.6 ka BP) is characterized by increasing C and N and a high N/P ratio (10-20) culminating in the early part of the Younger Dryas, indicating abundant N available for bio-production. The Fe, Mg, and K content is still high, but decreasing, indicating decreasing glacial and kryogenic erosion and allogenic deposition until c. 10.5 ka BP. A hiatus represented by a sand layer covers most of the time-span 10.5-9.6 ka BP. Chemostratigraphical unit 4 (9.6-5.3 ka BP) represents the Holocene thermal optimum in three subunits. In the time interval 9.6-9.1 ka BP, Fe, Mg and K decrease to a minimum and P shows a pronounced increase. The megathermal period c. 8200-5300 BP, is characterized by maxima of C, N and P and a minimum of Fe. The katathermal period after 5.3 ka BP is characterized primarily by increased Fe precipitation, increasing Fe/Mn ratio, and P, C and N at a constantly lower level than during the megathermal. A stable C/N ratio of about 10, of the sediment interval younger than 12.9 ka BP characterizes the sediments as transitional between gyttja and dy. The Holocene lake type varied between weakly oligohumic and mesohumic. Stagnant bottom waters (reducing conditions) occur in the periods 12.9-11.5 ka BP and c. 7.5-5.3 ka BP. The climatic development and other environmental implications of the joint chrono-, chemo-, litho- and biostratigraphical data set are discussed.  相似文献   

Late Quaternary history of northern Russia and adjacent shelves — a synopsis     

EILIV LARSEN  SVEND FUNDER  JÖRN THIEDE 《Boreas: An International Journal of Quaternary Research》1999,28(1):6-11

This synopsis highlights some of the main results presented in this issue of Boreas. The collection of papers deals with ice sheet reconstruction in space and time, isostatic and eustatic response to deglaciation, land to shelf sediment interaction, and Eemian and Holocene environmental variations. The most significant new results are that the last glacial maximum of the Kara Sea and Barents Sea ice sheets were both much smaller and much older than in most previous hypotheses. This puts new constraints on, for example, climate and ice sheet linkages, ice sheet interactions (Scandinavian-Barents Sea-Kara Sea), and land-ocean riverine input through time.  相似文献   

Moscovian (Carboniferous) microfossils (Bryozoa, Conodonta, and Fusulinida) from Novaya Zemlya, Arctic U.S.S.R.     

HANS A. NAKREM  INGER NILSSON  BJØRN T. SIMONSEN 《Polar research》1991,9(1):45-64

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