末次间冰期以来地球气候系统的突变   总被引：14，自引：0，他引：14  

秦蕴珊  李铁刚  苍树溪 《地球科学进展》2000,15(3):243-250

地球气候系统的突然变化是近年来地学研究的热点。取自极地冰芯、海洋沉积物和陆地的古气候记录表明,末次间冰期以来全球经历了一系列数百年—千年时间尺度的气候突变事件,证明了在末次冰期—间冰期旋回大尺度气候变化背景下,全球气候存在较大不稳定性这一基本事实。尽管末次间冰期以来这些数百年—千年时间尺度气候突变事件的成因和影响范围还存在明显的不确定性,但已从诸如末次间冰期(MIS 5e)中期的干冷事件、末次冰期的Dansgaard-Oeschger旋回、Heinrich事件和Younger Dryas事件以及发生在全新世冰后期的一些降温事件的研究中,获得对过去130 ka来气候变化过程总体上的认识和理解。综述了近年来的主要研究成果,介绍了有关末次间冰期以来全球气候突变事件发生的时间、过程和机制等最新的研究进展。  相似文献   

Glacial deposits at the Boyne Bay Limestone Quarry,Portsoy, and their place in the late Pleistocene history of northeast Scotland     

J. Douglas Peacock  Jon W. Merritt 《第四纪科学杂志》2000,15(5):543-555

The glacial deposits at the Boyne Bay Limestone Quarry near Portsoy, a key Quaternary Site of Special Scientific Interest, comprise (i) a sandy, partly weathered diamicton (Craig of Boyne Till Formation, CBTF) resting on decomposed bedrock, (ii) a central, variably glaciotectonised assemblage of dark clay, diamicton and sand, with rafts of sand and weathered diamicton (Whitehills Glacigenic Formation, WGF), and (iii) an upper dark sandy diamicton (Old Hythe Till Formation, OHTF). The CBTF was probably derived from the west or southwest, and the WGF from seawards. Structures within the OHTF conform to deposition by east‐ or southeast‐moving ice from the Moray Firth, but some erratics indicate derivation from the south. The CBTF is believed to pre‐date the last (lpswichian) interglacial, but the WGF and OHTF both post‐date the early Middle Devensian, and are probably of Late Devensian age. It is proposed that the OHTF was deposited by ice from inland which was directed eastwards near the coast by a vigorous glacier in the Moray Firth, and that the complex, Late Devensian glacial history of the south coast of the Moray Firth as a whole is the result of the interplay of these two contemporary ice‐masses. British Geological Survey. © NERC 2000.  相似文献   

A high‐resolution record of mire development and climatic change spanning the Late‐glacial–Holocene boundary at Church Moss,Davenham (Cheshire,England)     

P. D. M. Hughes  H. K. Kenward  A. R. Hall  F. D. Large 《第四纪科学杂志》2000,15(7):697-724

Excavations of deposits filling a closed basin within glacial drift at Church Moss, Davenham, near Northwich (Cheshire, England) revealed a sequence of Late‐glacial and Early Holocene sediments. Analyses of pollen and plant and invertebrate macrofossils were undertaken, together with loss‐on‐ignition analyses and a programme of AMS radiocarbon dating, to provide a record of changing biostratigraphy and climatic and ecological regimes. The infilling of features identified as frost‐cracks in the till flooring the basin gave remains that reflected conditions of extreme cold towards the end of the Devensian. The pollen record from a 3.5 m sequence of peat towards the deepest part of the basin, supported by radiocarbon dates, shows that organic deposition was initiated during the Late‐glacial Interstadial and continued into the early part of the Holocene. There was some evidence for a cool episode during the interstadial, with amelioration prior to the rapid onset of the tundra conditions of the Loch Lomond Stadial. Following the stadial, amelioration was rapid. There was evidence from both central and marginal sequences for a mosaic of fen dominated by sedges and often also mosses, with short‐lived small pools through much of the succession. Change to terrestrial conditions proceeded intermittently, probably as a result of subsidence caused by solution of underlying salt‐bearing strata. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

青藏高原冰期环境与冰期全球降温   总被引：36，自引：7，他引：29       下载免费PDF全文

刘东生  张新时 《第四纪研究》1999,19(5):385-396

根据青藏高原及其它地区的降温证据和降温条件下的环境变化模拟,讨论了青藏高原冰期环境变化及机制问题。从模拟结果看,在7～9℃降温条件下,高原冰雪带面积可占高原面积的1/5到1/2.考虑到降温条件下雪盖反射引起的高原冷却所起的正反馈作用,冰期高原上并不排除从山谷冰川发育较大冰盖的可能性。不管冰期高原上有无大面积的冰盖,青藏高原冰期环境出现大的变化是无疑问的。这种变化对冰期季风变化乃至全球气候变化的影响可能是深刻的。  相似文献   

北京猿人的环境与文化   总被引：5，自引：0，他引：5       下载免费PDF全文

徐钦琦  董为  刘金毅 《第四纪研究》1999,19(2):165-169

周口店第1地点是北京猿人的产地,他们在那里经历了3次冰川旋回或3个冰川年。北京猿人的文化可分为早、中、晚3个时期,它们恰好与3个冰川年完全吻合。晚新生代的几次生物进化事件总是发生在寒冷期的末尾或温暖期的开始。北京猿人石器制作技术水平的两次飞跃也都发生在寒冷期的末尾或温暖期的开始。如果把冰川旋回或冰川年也划分为春、夏、秋、冬的话,那么石器制作技术水平的飞跃和生物进化事件都是发生在冰川年的春季的。  相似文献   

地外撞击诱发的气候循环和新冰期的形成     

王世杰  欧阳自远  肖志峰 《地球科学》1999,24(6):568-572

考虑全球反照率随温度的变化,利用零维能量平衡模式,对撞击能量与其诱发的气候循环和注期形成之间的关系进行了计算模拟研究,当撞击坑的直径大于１５￣２０ｋｍ,全球气温在１ａ的时间里会产生快速的降温,降温幅度取决于撞击能量的大小,大约不到１００ａ的时间,下降趋势逐渐减缓,全球气温缓慢上升,并稳定在２５０Ｋ,如果没有 别的因素影响喧一平衡温度将会存在较长一段时间。有可能导致地球上冰期气候的形成结合新生代以来  相似文献   

Glacial–interglacial changes in Subantarctic sea surface temperature and δO-water using foraminiferal Mg     

Tracy A. Mashiotta  David W. Lea  Howard J. Spero 《Earth and Planetary Science Letters》1999,170(4):113-432

Laboratory culturing experiments with living Globigerina bulloides indicate that Mg/Ca is primarily a function of seawater temperature and suggest that Mg/Ca of fossil specimens is an effective paleotemperature proxy. Using culturing results and a core-top Neogloboquadrina pachyderma calibration, we have estimated glacial–interglacial changes in sea surface temperature (SST) using planktonic Mg/Ca records from core RC11-120 in the Subantarctic Indian Ocean (43°S, 80°E) and core E11-2 in the Subantarctic Pacific Ocean (56°S, 115°W). Our results suggest that glacial SST was about 4°C cooler in the Subantarctic Indian Ocean and 2.5°C cooler in the Subantarctic Pacific. Comparison of SST and planktonic δ¹⁸O records indicates that changes in SST lead changes in δ¹⁸O by on average 1–3 kyr. The glacial–interglacial temperature change indicated by the Subantarctic Mg/Ca records suggests that temperature accounts for 40–60% of the foraminiferal δ¹⁸O change. We have used the Mg/Ca-based SST estimates and δ¹⁸O determinations to generate site-specific seawater δ¹⁸O records, which suggest that seawater δ¹⁸O was on average 1‰ more positive during glacial episodes compared with interglacial episodes.  相似文献   

玉龙山东麓更新世冰川作用   总被引：34，自引：7，他引：27  

赵希涛  李铁松 《冰川冻土》1999,21(3):242-248

利用１：１００００地形图和航空照片,对玉龙山东麓更新世冰川作用遗迹进行了调查和填图。据冰川与冰水沉积物的钙质胶结物和冰湖相钙板的ＥＳＲ测年结果,初步划分４次冰期,即０．７￣０．６Ｍａ ＢＰ的玉龙冰期。其中最早一次冰期为规模较大的山麓冰川,后２次冰期为规模较大的山谷冰川。  相似文献   

极地深层冰川微生物研究的现状与意义   总被引：5，自引：0，他引：5       下载免费PDF全文

张晓君  姚檀栋  马晓军 《极地研究》2000,12(4):269-274

极地冰芯的研究对于揭示过去环境的变化规律和预测未来气候环境具有重要意义 ,我国科学家在此领域取得了一系列丰硕成果 ,跨入了国际领先行列。冰芯微生物的研究在国外近年来才刚刚开始 ,并且日益受到重视。南北极和低纬度地区高山冰川深层冰芯中封藏着几千年甚至几十万年的微生物 ,对它们的研究将为微生物多样性研究、过去环境的变迁、生物基因的进化甚至生命起源的研究开辟新的途径  相似文献   

The fossil oribatid mite fauna (Acari: Oribatida) in late-glacial and early-Holocene sediments in Kråkenes Lake, western Norway   总被引：2，自引：0，他引：2  

Ingrid Wunderle Solhøy  Torstein Solhøy 《Journal of Paleolimnology》2000,23(1):35-47

The oribatid mite assemblages found in late-glacial and early-Holocene sediments in Kråkenes Lake, western Norway, consist of 38 species within 24 genera. In accordance with known present habitat distribution we distinguish 4 true aquatic species, 6 species associated with wetland, 2 with mesic grassland, 12 with dry grassland and heathland, 3 with saxicolous and arboricolous lichens, 7 widely distributed species, and 4 with uncertainly known habitat preferences. The sediments from the pioneer phase (12,300-11,700 ¹⁴C BP) contain 7 species, among them the 2 typical pioneer species Limnozetes ciliatus and Tectocepheus velatus.The sediments of the warmer Allerød interstadial (11,700-10,900 BP) contain 18 species, the cold Younger Dryas (10,900-10,000 BP) 9 species, and the early Holocene (10,000-9,000 BP) 36 species.The oribatid fossils of the pioneer phase indicate habitats and climate similar to the mid-alpine zone in western Norway today, the Allerod interstadial that of the low- to mid-alpine zone. L. ciliatus is the aquatic pioneer species in the Allerod. In the Younger Dryas the climate was more arctic, 60-70% of the species had presumably disappeared, and no aquatic species were found. In the early Holocene, 4 true aquatic species colonised the lake and showed a high productivity. The terrestrial oribatid fauna in this period contained a high diversity of more boreal species, while the alpine species declined or became extinct.  相似文献