Late Middle Pleistocene deposits at Norton Farm on the West Sussex coastal plain,southern England     

Martin R. Bates  C. Richard Bates  Philip L. Gibbard  Richard I. Macphail  Frederick J. Owen  Simon A. Parfitt  Richard C. Preece  Mark B. Roberts  J. Eric Robinson  John E. Whittaker  Keith N. Wilkinson 《第四纪科学杂志》2000,15(1):61-89

The coastal plain of West Sussex, southern England, is internationally important because of the sequence of discrete high‐sea‐level events preserved at various elevations across it. New evidence is presented from a site at Norton Farm, near Chichester, on the Lower Coastal Plain, where Pleistocene marine sands, fining upwards into silts, occur between 5.3 m and 9.1 m OD. The sequence reflects a regressive tendency at the transition from an interglacial to a cold stage. The marine sands have yielded foraminifera, ostracods and molluscs that indicate a declining marine influence through the sequence, culminating in a tidal mudflat, strongly weathered in places. Cool‐climate foraminifera (including Elphidium clavatum, Cassidulina reniformis and Elphidium albiumbilicatum) and ostracods have been recovered from the marine sands. Some species with an apparent preference for warmer water conditions, however, are also present. Freshwater taxa washed into the terminal marine sediments include some cold climate indicators, such as Pisidium stewarti and P. obtusale lapponicum. Additional evidence for cool climatic conditions during the deposition of the upper part of the marine sequence is provided by the lack of tree taxa in the pollen record and by features of the micromorphology. The marine sediments probably began accumulating during OIS 7, a conclusion based on their elevation, on amino acid ratios from shells, but especially on vertebrate evidence, particularly the presence of a small form of horse, together with a large, distinctive, form of northern vole (Microtus oeconomus). The occurrence of cool climate indicators in these marine sediments may demonstrate a lag between the climatic deterioration and the expected glacio‐eustatic fall in relative sea‐level. This evidence appears to support the conclusions drawn from the study of coral terraces in Barbados. Such a scenario would provide the conditions necessary for the emplacement of the large erratic boulders reported from the Lower Coastal Plain of West Sussex. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

Marine evidence for the last glacial advance across eastern Hudson Strait,eastern Canadian Arctic     

Anne E. Jennings  William F. Manley  Brian Maclean  John T. Andrews 《第四纪科学杂志》1998,13(6):501-514

Data from accelerator mass spectrometer radiocarbon dated sediment cores and Huntec high-resolution seismic profiles were used to investigate the age and origin of the sediments in the Eastern Basin of Hudson Strait. The data indicate that the ice-contact and glacial-marine sediments on the basin flanks and much of the upper sequence in the deep floor of the basin were produced during the Noble Inlet advance (8.9 to 8.4 ka), the last northward expansion of the Labrador Dome on to southeastern Baffin Island. On the northern flank of Eastern Basin one sequence of ice-contact sediments and glacial-marine deposits overlies bedrock; the glacial-marine sediments are transitional upslope to ice-contact sediments, and form at least two successive ice-sheet grounding zones. The earliest abundance peaks of benthic Foramininfera in glacial-marine sediments date ca. 8.6 and 8.4 ka, and correlate to sediments near the base of the 58-m-thick glacial-marine section in the deepest part of Eastern Basin. This correlation suggests that Noble Inlet ice was grounded throughout Eastern Basin during the early part of its advance. In later stages the thinning ice produced grounding zones on the basin flanks while glacial-marine sediments were deposited in the deep basin. © 1998 John Wiley & Sons, Ltd.  相似文献   

Late Cretaceous Foraminiferal Faunas from the Saiqu "mélange" in Southern Tibet     

LI Guobiao  WAN Xiaoqiao  JIANG Ganqing  HU Xiumian  GOUDEMAND Nicolas  HAN Hongdou  CHEN Xi 《《地质学报》英文版》2007,81(6)

As one of the mélanges in the southern side of the Yarlung-Zangbo suture zone, the Saiqu mélange in southern Tibet is important for understanding the evolution of the Neo-Tethys ocean. The age of the Saiqu mélange, however, has been debated due to the lack of reliable fossil evidence in matrix strata. Based on lithological similarities with platform strata in southern Tibet and limited fossils from exotic blocks, previous studies variously ascribed the Saiqu mélange to be Triassic in general, Late Triassic, or Late Cretaceous. Here we reported planktonic foraminiferal faunas from the matrix strata of the Saiqu mélange. The new fossils yield a Late Cretaceous age, which is so far the best age constraint for the mélange. Regional stratigraphic correlation indicates that the Cretaceous Oceanic Red Beds (CORBs) in Saiqu may be time equivalent to the CORBs of the Zongzhuo Formation in neighboring regions. Thus the Saiqu mélange should be correlated to the Upper Cretaceous Zongzhuo Formation rather than the Triassic Xiukang Group, as previously suggested.  相似文献   

Benthic foraminifera and sediment grain size variability at intermediate water depths in the Northeast Atlantic during the late Pliocene–early Pleistocene     

W. E. N. Austin  J. R. Evans 《Marine Geology》2000,170(3-4):423-441

Sedimentological and faunal records from the transitional period marking the onset of widespread northern hemisphere glaciation have been investigated at Ocean Drilling Program Site 984. The late Pliocene interglacial sediments of the northeast Atlantic are carbonate rich and show evidence of vigorous bottom water circulation at intermediate water depths. Contrasting this, the late Pliocene glacial sediments are characterised by carbonate dissolution and slower bottom current velocities. Weak or “leaky” Norwegian Sea overflows, undersaturated with respect to carbonate, influenced this region during the late Pliocene glacials. The early Pleistocene pattern of intermediate water circulation appears to have changed radically in the northeast Atlantic. At this time, interglacial carbonate values and inferred bottom current velocities are low. This suggests slow-flowing, undersaturated Norwegian Sea water bathing the site. The overflow increased during the early Pleistocene interglacials as the exchange between the Atlantic and Norwegian-Greenland Seas improved. The most significant feature of the early Pleistocene glacials is the increase in inferred bottom current velocity. These changes reflect a switch in deep North Atlantic convection to shallower depths during glacial periods, possibly in a manner similar to the increasing contribution of glacial intermediate water to the North Atlantic during the late Pleistocene glacials. Our results suggest that the late Pleistocene climate variability of the North Atlantic is a pervasive feature of the late Pliocene–early Pleistocene record.  相似文献   

冲绳海槽南部表层沉积中的浮游有孔虫及其地质意义   总被引：3，自引：0，他引：3  

陈荣华  翦知湣  郑玉龙 《海洋学报》1999,21(5):78-86

对冲绳海槽南部53个表层沉积样品中大于0.154mm的浮游有孔虫进行系统鉴定和定量统计,并采用Q型因子分析,求得浮游有孔虫各属种和组合的分布特征:N.Dutertei－p.Obliquiloculata组合主要分布在离大陆和台湾岛较近的地方,而G.Glutinata－G.Ruber组合则主要分布在冲绳海槽的中央及靠琉球岛的一侧,且发现浮游有孔虫丰度、属种组合和碎壳率等的分布和变化主要受控于水深、碳酸盐溶跃层、温跃层以及水团等各类环境因子.  相似文献   

A high-resolution record of Lateglacial and early Holocene marine sediments from southwestern Sweden; with special emphasis on environmental changes close to the Pleistocene-Holocene transition and the influence of fresh water from the Baltic basin     

Helene Bergsten 《第四纪科学杂志》1994,9(1):1-12

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Les « Sables fauves », témoins de mouvements tectoniques dans le bassin d'Aquitaine au Miocène moyenThe ‘Sables fauves’, showing tectonic deformations in the Aquitaine Basin during Middle Miocene     

Philippe Gardère  Jacques Rey  Francis Duranthon 《Comptes Rendus Geoscience》2002,334(13):987-994

New data about the ‘Sables fauves’ clearly show two different kinds of organisations: stratigraphic superposition of Langhian and Serravallian units to the south and embankment of Serravallian sediments in Langhian deposits to the north. The result consists in two different palaeogeographic schemes. The Langhian Sea is widely extended, forming the ‘Lectoure Gulf’, whereas the Serravallian Sea is much more reduced, with valleys fillings to the north and a little gulf to the south. This involves a tectonic activity along a structure which orientation is N120°E (‘flexure de la Douze’) and a relative rising of the northern part, of about 30 m. To cite this article: P. Gardère et al., C. R. Geoscience 334 (2002) 987–994.  相似文献   

A record of Miocene carbon excursions in the South China Sea     

ZHAO Quanhong  WANG PinXian  CHENG Xinrong  Wang Jiliang  Huang Baoqi  XU Jian  ZHOU Zhen  JIAN Zhimin 《中国科学D辑(英文版)》2001,44(10):943-951

High-resolution δ¹³C records are presented for the Miocene benthic foraminifersCibicidoides wuellerstorfi andC. kullenbergi (24-5 Ma) and the planktonic foraminiferGlobigerinoides sacculifer (18-5 Ma) from ODP Site 1148A (18° 50.17’N, 116° 33.93’E, water depth 3308.3 m), northern South China Sea. The general pattern of parallel benthic and planktonic δ¹³C shows a decrease trend of δ¹³C values from the early-middle Miocene to the middle-late Miocene. Two distinct δ¹³C positive excursions at 23.1-22.2 and 17.3-13.6 Ma, and two negative excursions at 10.2-9.4 and 6.9-6.2 Ma have been recognized. All these events are cosmopolitan, providing the good data for the stratigraphic correlation of the South China Sea with the global oceans as well as for studying the changes of the global carbon reservoir and its corresponding climate.  相似文献   

江苏海岸带沉积环境中的有孔虫埋葬群特征   总被引：1，自引：0，他引：1  

朱晓东  任美锷  王颖 《海洋科学》1997,21(2):52-56

研究结果表明，江苏海岸有孔虫埋葬群可划分为：南部长江河口海岸区，中部辐射沙洲及其娄砂质海岸区和北部海州湾区３大类群。这３类埋葬各自的特点并与当地的沉积环境相对应，各大环境又包含若干亚环境，可依据各亚环境有孔虫埋葬群的特点加以区分。  相似文献   

沉积有孔虫作为上升流指标的可行性研究     

程广芬  周颖春 《中国海洋大学学报(自然科学版)》1991,(1)

研究了取自加里福尼亚湾的五个岩心。结果表明:沉积有孔虫组合作为上升流指标用于古海洋学研究是行之有效的。  相似文献