摘要:

The glaciotectonic deformations near the northeastern margin of the Sudetic Foreland, SW Poland. were formed during one glacial episode. They are relatively small and are truncated. Deformation structures have no recognizable relationship to the thick Neogene clay in the basement; they have variable relations to the morphology and indicate transverse to opposite directions of the glacial push in very small areas within a distance of 2 to 5 km. This suggests an unusual deformational history. Deformations have probably been created due to sliearingen masseof the anisotropic sediments and during the ice‐sheet advance. Deformation structures have been formed a few kilometres ahead of the curved ice margin, which created ‘glaciotectonic hills’ with strongly differentiated orientations of thrust structures and

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1996.tb00638.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The glaciotectonic processes that have shaped the morphology and structural geology of the Comfortlessbreen thrust‐moraine complex are shown to be largely proglacial in origin, with the development of low‐angle thrusts, nappe‐like structures and folds. The propagation of the deformation has extended into the glacier foreland. A style of deformation called the ‘englacial deformation zone’ explains the incorporation of subglacial debris into the ice by thrusting and subsequent deposition of thrust sheets is inherited from the ice structures. A model for thrust‐moraine development and its possible chronology at Comfortlessbreen emphasizes the role played by glaciomarine sediment in facilitating deformation and also the role of thrusting, rathcr than pushing, in moraine formation. The importance of sediment type in controlling the overall development of the moraine is emphasized and a comparison to illustrate this control is made with neighbouring

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1996.tb00639.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The deglaciation of the continental shelf to the west of Spitsbergen and the main fjord, Isfjorden. is discussed based on sub‐bottom seismic records and scdirncnt cores. The sea lloor on the shelf to the west of Isfjorden is underlain by less than 2 m of glaciomarine sediments over a firm diamicton interpreted as till. In central Isfjordcn up to 10 m of deglaciation sediments were recorded, whereas in cores from the innermost tributary, Billefjorden, less than a meter of ice proximal sediments was recognized between the till and the ‘normal’ Holocene marine sediments. We conclude that the Barents Sea Ice Sheet terminated along the shelf break during the Late Weichselian glacial maximum. Radiocarbon dates from thc glaciomarine sediments above the till indicate a stepwise deglaciation. Apparently the ice front rctrcatcd from the outermost shelf around 14. 8 ka A dramatic increase in the flux of line‐grained glaciomarine sediments around 13 ka is assumed to reflect increased melting and/or current activity due to a climatic warming. This second stage of deglaciation was intcrruptcd by a glacial readvance culminating on the mid‐shelf area shortly after 12.4 ka. The glacial readvance, which is correlated with a simultaneous readvance of the Fennoscundian ice sheet along the western coast of Norway, is attributed to the so‐called ‘Older Dryas’ cooling event in the North Atlantic region. Following this glacial readvance the outer part of Isljorden became rapidly deglaciated around 12.3 ka. During the Younger Dryas the inner fjord branches were occupied by large outlet glaciers and possibly the ice liont terminated far out in the main fjord. The remnants of the Harcnts Sea Ice Shcet melted quickly away as a response to the Holocene warmi

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1996.tb00640.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Oxygen‐isotope profiles for the Late‐Glacial carbonate sediments from Red Bog and adjacent Lough Gur in County Limerick in western Ireland are readily correlated with the classical hiozones delineated on pollen diagrams for the same cores. The estimated summer temperatures of the Bølling/Allerød were as high as those in the early Holocene and are correlated with increasing Milankovitch summer insolation. This warm phase was abruptly terminated in the Younger Dryas cold episode by a depletion of 4% in δ18O, suggesting a summer atmospheric temperature decrease of about 12°C, comparable to that inferred from fossil beetle data. The Younger Dryas phase is attributed to a major cooling of the sea‐surface temperature by a postulated discharge of icebergs similar to that of the Heinrich events, for the icebergs were much more effective than simple meltwater in cooling the sea surface and thus the climate over Europe. Shorter‐term cool phases (Older Dryas. Gerzensee. Preboreal oscillation) are also

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1996.tb00641.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Noe‐Nygaard. Nanna. 1995:Ecologicol, Sedimentary, trnd Geonchemical Evolution of the Late‐glarcial to Postglacial Åmiose Locustrine Basin. Denmark. Fossils and S

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1996.tb00642.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Ehlers, J., Kozarski, S.&Gibbard, P. (eds) 1995:Glacial Deposits in North‐East Euro

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1996.tb00643.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

A two‐step climatic warming and oceanographic change during the Younger Dryas/Preboreal transition was registered by diatom, foraminiferal, mollusc, lithologic data and sediment accumulation rates in a high resolution sediment core from the Swedish west coast. An abrupt climatic warming in the surface water of the Kattegat occurred atc. 10 200 BP, resulting in a rapid increase in sea surface water temperatures. The attenuation of meltwater discharge into the Kattegat led to an increase in sea surface salinity. Consequently, the difference in salinity through the water column diminished. This change happened within less than 80 years. The warming of bottom water in the deeper parts of the region took place a few hundred years after the surface water warming. The climatic amelioration was recorded by increased meltwater discharge and a slight increase in abundance of relatively warm diatoms around 10 600 BP at the time of the recession of the Fennoscandian ice sheet. An increase in the number of arctic/subarctic benthic foraminifera shows that the bottom water temperature during this period was still relatively lo

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1996.tb00644.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The Ferdynandovian Interglacial is one of the most controversial Quaternary stratigraphic horizons in Europe. This study concentrates on palaeoclimatic reconstruction of this interglacial based on pollen succession, isotope composition and magnetic susceptibility. The section investigated is located in the open cast mine at Belchatow, central Poland. The lacustrine sequence contains laminated diatomite at the base, which was deposited in deep, meromictic lake, and massive diatomite to calcareous gyttja in its upper part. The latter were deposited in a holomictic lake, which became progressively more shallow. The gradual increase of δ18O values and simultaneous decrease of susceptibility in the lower part of the Ferdynandovian sequence at Belchatow correspond well with climatic amelioration documented by pollen analysis. Simultaneous increase of precipitation of carbonates and its δ13C values correspond well with the increase in biological activity in the lake. Results obtained by isotope investigations showed an increase in the mean annual temperature to a maximum of 7.5°C from the beginning of the interglacial to the first appearance of thermophilous, deciduous trees. The oxygen‐isotope curve does not show any short‐term climatic oscillations. Susceptibility oscillations are somewhat more distinct, but because the main magnetic carrier is greigite deposited on spores of unicellular organisms, they are linked to the concentration of these spores rather than with the climatic oscillations. Twelve secular cycles or their fragments have been recorded in the interglacial sequence by palaeomagnetic investigations, suggestingc. 9600 years of deposition. This corresponds well with the 10 000 years of deposition calculated for the same sequence based on annually laminated diat

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1996.tb00645.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1996.tb00646.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY