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   

A shift towards wetter and windier conditions in southern Sweden around the prominent solar minimum 2750 cal a BP          下载免费PDF全文

ANETTE MELLSTRÖM  NATHALIE VAN DER PUTTEN  RAIMUND MUSCHELER  RIXT DE JONG  SVANTE BJÖRCK 《第四纪科学杂志》2015,30(3):235-244

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Late Weichselian to early Holocene sedimentation in a steep fjord/valley setting, Visdalen, Edgeøya, eastern Svalbard: glacial deposits, alluvial/colluvial-fan deltas and spit-platforms     

PER MÖLLER  OLE P. STUBDRUP  CHRISTIAN KRONBORG 《Polar research》1995,14(2):181-203

The Visdalen valley, situated at the northwestern corner of Edgeøya, was investigated with respect to lithostratigraphy and depositional environments of the Quaternary sediments. Eight major lithostratigraphic units are recognised of which seven were deposited during the Late Weichselian to early Holocene glaciation, deglaciation and the subsequent emergence of the area, and one unit deposited prior the last glaciation. Till deposition from a west-flowing glacier was followed by glaciomarine and later marine deposition of fine-grained sediments. Coarse-grained colluvial and alluvial-fan deltas were deposited along the mountainsides in the Visdalen palaeo-bay, and distal sediment gravity-flow deposits from these deltas were interbedded with the glaciomarine-marine sediments. A spit-platform (riegel) was built up across the Visdalen bay contemporaneously with the alluvial fan-deltas. Its formation was time-transgressive, with its highest part in the south close to the marine limit at 85 m a.s.l. and its lowest part in the north at ca 65 m a.s.l. The sediment source was alluvial and colluvial debris, which was entrained by longshore currents along the more exposed coast south of Visdalen and transported northwards to the final place of deposition. The bulk part of the riegel ridge is composed of progradational successions of steep foresets dipping towards NW, N and NE, and clearly rejects an earlier ice-contact model. Datings suggest that the fan-delta deposition and the riegel formation ended before 9,000 BP. A meltwater-fed lagoon with a highest level at >50m a.s.l. was formed behind the riegel ridge in which, according to varve counting, glaciolacustrine sedimentation lasted more than 250 years and occurred within the time span 9,000-8,500 BP. Gradual uplift of the area resulted in drainage of the glaciolacustrine lagoon. Beachface processes and fluvial down-cutting took place during the emergence of the area.  相似文献   

REPRESENTATION OF SPECTRA BY CONTINUOUS FUNCTIONS     

BJRN K.ALSBERG 《地理学报(英文版)》1993,(3)

A general framework for manipulating spectra as functions in traditional multivariate methods such asPCA and PLS is described.The functional representation is very convenient for compression,ensuringsmoothness and continuity.There are two fundamentally different types of representations:(a)byfunctions and(b)by function coefficients.The use of coefficients is the most practical way of analysis.  相似文献   

豫西嵩县前范岭石英脉型钼矿床地质特征及辉钼矿Re-Os同位素年龄   总被引：14，自引：2，他引：12  

高阳  李永峰  郭保健  程国祥  刘彦伟 《岩石学报》2010,26(3):757-767

位于熊耳山-外方山地区的前范岭钼矿是东秦岭地区新近发现的石英脉型钼矿床之一。赋矿围岩为古元古界熊耳群安山质火山岩类。矿体主要以含辉钼矿石英脉产出,矿石类型以石英脉型为主。金属矿物以辉钼矿和黄铁矿为主,脉石矿物以石英为主,其次为方解石、萤石等。围岩蚀变类型有硅化、钾长石化、青磐岩化等。对6件辉钼矿样品进行Re-Os同位素测年所获得的模式年龄为233.3±3.3～248.2±3.5Ma,等时线年龄为239±13Ma,表明矿床形成于中三叠世。矿床的成矿作用发生于华北与扬子两个板块碰撞对接的晚期阶段。区域上整体的挤压造成了局部的剪切和伸展环境,这种环境为控矿断裂的形成和成矿流体的运移提供了有利条件。嵩县境内现已发现的多处脉型钼矿床很可能形成于同一时期(三叠纪),它们构成了熊耳山与外方山之间的嵩县脉型钼矿田。  相似文献   

AMS ¹⁴C measurements and macrofossil analyses of a varved sequence near Pudozh, eastern Karelia, NW Russia     

BARBARA WOHLFARTH  OLE BENNIKE  LARS BRUNNBERG  IGOR DEMEDOV  GÖRAN POSSNERT  SERGEI VYAHIREV 《Boreas: An International Journal of Quaternary Research》1999,28(4):575-586

The laminated sediments at Pudozh in eastern Karelia are generally assumed to have been deposited between 13 000 and 16 000 ¹⁴C yr BP and have been used to date the recession of the active ice margin. However, 17 AMS ¹⁴C measurements performed on terrestrial plant macrofossils contained in these sediments show that deposition began during the late Allerφd, when the ice margin had already receded to the northern part of Lake Onega. Based on an age model, we assume that the 1933-year-long varved sequence covers the time period between c. 12 900 and 11 000 calendar years BP. During this period, which comprises the later part of the Late Weichselian and the early Holocene, the local vegetation consisted of open, tree-less dwarf shrub heaths. Increased soil erosion may have occurred before 12 550 calendar years BP.  相似文献   

Lake Boksehandsken's earliest postglacial sediments and their palaeoenvironmental implications, Jameson Land, East Greenland     

SVANTE BJÖRCK  OLE BENNIKE  ÓLAFUR INGÓLFSSON  LENA BARNEKOW  DAVID N. PENNEY 《Boreas: An International Journal of Quaternary Research》1994,23(4):459-472

Lake Boksehandsken, the largest lake on Jameson Land, central East Greenland, is situated 54 m a.s.l. and holds a long (6.3 m) and complex stratigraphy. It was analysed with respect to lithology, carbon content, ¹⁴C, micro- and macrofossils. The diamict material in the bottom is overlain by a fining-upwards sequence, possibly deposited close to a receding ice margin in a glaciomarine environment. These deposits are interpreted to have been formed at the time of the marine limit ( c . 70 m) in the area. In spite of a large series of ¹⁴C datings, very few of the obtained dates were considered reliable. This is because the sediments contain coal fragments and old redeposited plant remains. Based on a set of arguments and correlations to the surrounding glacial stratigraphy it is implied that the marine limit and deglaciation cannot be much older than 10,000 BP. The lithology of the lake sediments, in combination with occurrence of marine macrofossils. shows that deglaciation was succeeded by a (glacio)marine depositional environment. The lake was isolated from the sea at c . 9000 BP. followed by a short transgression and a final isolation at c . 8400 BP. This sequence of events is demonstrated by both litho-and biostratigraphy and possible causes are discussed. A later oscillation some time between 8000 and 7500 BP. evidenced by litho-, carbon-, pollen- and Pecliastrum stratigraphy, is interpreted as a regional climatic cooling possibly correlatable to a distinct δ¹⁸O minima in the Greenland ice cores.  相似文献   

A diver-operated electric suction sampler for sympagic (= under-ice) invertebrates   总被引：3，自引：0，他引：3  

OLE JØRGEN LøNNE 《Polar research》1988,6(1):135-136

The construction and operation of a diver-operated suction sampler for sympagic fauna are described. An interchangeable sampling cylinder with a 0.5 mm sieve connected to a battery driven turbine pump makes it possible to'vacuum'predetermined areas of the ice under-surface, even if the surface is rugged and perforated by brine channels. Several samples can be obtained during one dive by using different sampling cylinders.  相似文献   

Lake sediments from Store Koldewey, Northeast Greenland, as archive of Late Pleistocene and Holocene climatic and environmental changes     

MARTIN KLUG  STEFFI SCHMIDT  OLE BENNIKE  OLIVER HEIRI  MARTIN MELLES  BERND WAGNER 《Boreas: An International Journal of Quaternary Research》2009,38(1):59-71

A 2.9 m long sedimentary record was studied from a small lake, here referred to as Duck Lake, located at 76°25'N, 18°45'W on Store Koldewey, an elongated island off the coast of Northeast Greenland. The sediments were investigated for their geophysical and biogeochemical characteristics, and for their fossil chironomid assemblages. Organic matter began to accumulate in the lake at 9.1 cal. kyr BP, which provides a minimum age for the deglaciation of the basin. Although the early to mid-Holocene is known as a thermal maximum in East Greenland, organic matter accumulation in the lake remained low during the early Holocene, likely due to late plant immigration and lack of nutrient availability. Organic matter accumulation increased during the middle and late Holocene, when temperatures in East Greenland gradually decreased. Enhanced soil formation probably led to higher nutrient availability and increased production in the lake. Chironomids are abundant throughout the record after 9.1 cal. kyr BP and seem to react sensitively to changes in temperature and nutrient availability. It is concluded that relative temperature reconstructions based on biogeochemical data have to be regarded critically, particularly in the period shortly after deglaciation when nutrient availability was low. Chironomids may be a suitable tool for climatic reconstructions even in those high arctic environments. However, a better understanding of the ecology of chironomids under these extreme conditions is needed.  相似文献