Precise dating of East-Asian-Monsoon D/O events during 95―56 ka BP: Based on stalagmite data from Shanbao Cave at Shennongjia, China     

XIA ZhiFeng  KONG XingGong  JIANG XiuYang  CHENG Hai 《中国科学D辑(英文版)》2007,50(2)

Based on 23 U/Th analyses and 532 oxygen isotopic data, an averaged 80-a stalagmite oxygen isotopic composition series was established through 95 to 56 thousand years before present (ka BP) from two speleothems in Shanbao Cave, Shennongjia, central China. Shanbao Cave record (referred to as SB record) replicates well with Hulu Cave record, extending the characteristics of millennial oscillations in East-Asian-Summer-Monsoon (EASM) to the past 95 ka. The trend of the SB record generally follows mid-July solar insolation at 65°N, suggesting that mid-high northern latitude insolation, in the first order, controls changes of EASM intensity. Millennial oscillations of EASM recorded in the stalagmites are well related to the Greenland interstadials referred to as Dansgaard/Oeschger (D/O) events from 1 to 22, indicating that rapid ocean-atmosphere reorganization in North Atlantic has a remote effect in EASM. The well-dated D/O events by stalagmites probably provide an absolute calibration for chronologies of Greenland ice cores. The timings of D/O events in the SB record are different variously from those in Greenland ice cores. For D/O 19 and 20, the age offsets between the stalagmites' and the Greenland ice cores' record are significant, larger than the uncertainties of uranium-series dating. The two events in the SB record are younger than those in North GRIP time scale by 1―2 ka, and older than the counterparts in GISP2 by approximately 3―4 ka. A comparison between the SB and Brazil stalagmite record shows an anti-phase relation in millennial-scale monsoon precipitation between the two localities. This supports a mode for the coupled ocean-atmosphere "See-saw".  相似文献   

川西沙鲁里山第四纪冰川及与邻区之对比     

曹俊  赵友年 《四川地质学报》2007,27(2):81-86

沙鲁里山是研究第四纪冰川的最佳场所之一。可划分四个冰期,第一冰期为大陆冰盖,第二、三期及现代冰川为山岳冰川;整体反映第四纪地壳不断抬升,气候不断变暖,冰川不断向高山退缩的过程。  相似文献   

南黄海、东海陆架及冲绳海槽北部 沉积物的¹⁰ Be和⁹ Be记录^*     

杨永亮  刘振夏  沈承德  石学法  李铁刚  徐清  潘静  程振波  熊应乾  H.Matsuzaki 《第四纪研究》2007,27(4):529-538

文章讨论了南黄海泥质区、东海陆架及冲绳海槽北部表层沉积物和柱状岩芯中¹⁰ Be及⁹ Be含量的水平和垂直分布,并与重金属Pb的分布进行了比较。表层沉积物中的¹⁰ Be,⁹ Be和Pb三者表现出完全不同的分布特征。¹⁰ Be的分布主要受黑潮及其支流黄海暖流所支配; ⁹ Be的分布受黄河陆源物质输入的影响,主要集中在南黄海泥质区; Pb则主要分布在长江口和琉球群岛附近,反映了人类活动的影响。冲绳海槽北部末次冰期和全新世时¹⁰ Be的沉积通量变化在整体上反映了¹⁰ Be大气生产率的变化,即地球磁场屏蔽效应的影响。03孔全新世时¹⁰ Be的沉积通量 (1.12×10⁹atoms/cm²ka)基本上等于¹⁰ Be的现代大气平均生产率,而在末次冰期时平均为4.06×10⁹atoms/cm²ka, 高于¹⁰ Be 的现代大气平均生产率3倍以上。在冲绳海槽由于黑潮的缘故,¹⁰ Be对气候的变化响应要比极地冰芯的¹⁰ Be变化响应灵敏的多,对气候变化信号起了放大的作用。冰期时冲绳海槽北部¹⁰ Be的沉积通量远远高于太平洋大洋海区,充分反映了黑潮的传送带作用和边缘海的聚焦沉积作用,并表明末次冰期时在千年尺度上黑潮仍流经冲绳海槽,且强度并未减弱。 ¹⁰ Be的通量在新仙女木时降到整个岩芯所跨时期的最低点,甚至低于¹⁰ Be的现代大气平均生产率,因此推测在新仙女木事件时,黑潮的变动特别大,有可能改向或断流。  相似文献   

青藏高原若干地点的第四纪冰川年代学^* ——深切怀念孙殿卿院士   总被引：1，自引：1，他引：1  

赵志中  钱方  刘宗秀  田国强  李名则  苗琦  谭征兵  J.M.Schaefer  P.Oberholzer  S.Strasky  Ch.Schlüechter  吴锡浩 《第四纪研究》2007,27(5):669-673

青藏高原第四纪冰川时空演化问题广受关注。应用宇宙成因核素暴露年龄测定方法开展高原古冰川的年代学研究,对青藏高原聂拉木、唐古拉山、义敦海子山和折多山等4个地区的第四纪冰碛物进行了\{¹⁰ Be\},²⁶ Al和²¹ Ne暴露年龄测定,获得了青藏高原不同地点第四纪冰川发育的年代学数据,结果表明青藏高原出现了多期第四纪冰期,分别为YD事件、末次冰期晚阶段、末次冰期早阶段、倒数第2次冰期和倒数第3次冰期。  相似文献   

Glacial meltwater and sea ice meltwater in the Prydz Bay, Antarctica     

蔡平河  黄奕普  陈敏  刘广山  邱雨生  陈性保  金德秋  周锡煌 《中国科学D辑(英文版)》2003,46(1)

It has been well known by oceanographers that the World Ocean Circulation originates inNorth Atlantic near the Greenland, where in wintertime the cooled surface water descends to form North Atlantic Deep Waters (NADW). The NADW, when passing the Antarctic…  相似文献   

利用陆面岩石中生成的宇生同位素重建冰川漂砾运动历史的尝试   总被引：3，自引：0，他引：3       下载免费PDF全文

王建  FrancoisYiou  GrandRaisbeck  徐孝彬 《地质学报》2003,77(3):407-413

冰川漂砾的形成年代通常难以直接测定，并且漂砾形成以后是否被再次搬运或者移动过，更是无法知道。本文研究发现，通过测试砾石不同部位的宇生同位素，不仅可以测定砾石形成的时代，而且可以确定砾石再次被搬运或者被翻转的年代，从而恢复砾石运动的历史。本文以石英中生成的宇生同位素^10Be，对青藏高原东南部海子山的冰川漂砾进行了探讨，结果表明该砾石形成于倒数第二次冰期(186～128ka BP之间)，在末次冰期中再次被冰川搬运，使之反转。该方法不局限于^10Be和冰川漂砾，也适用于其他陆面岩石中生成的宇生同位素以及其他成因的石块或者砾石。因此为探讨冰川作用、泥石流活动、重力崩塌等过程提供了一种重要的方法和技术途径。  相似文献   

末次冰期东亚冰川规模与冰川进退异时性问题     

张威  崔之久  李永化 《地理学报(英文版)》2005,15(3):293-304

1 IntroductionIthas been accepted thatthe glacialextentin the early stage w as largerthan thatin the late stagein Eastern A sia during the Last G laciation and w as different from Europe and N orth A m erica(Li, 1992; Cui et al., 2000). M any scholars hav…  相似文献   

LATE‐GLACIAL GLACIER EVENTS IN SOUTHERNMOST SOUTH AMERICA: A BLEND OF ‘NORTHERN’ AND 'SOUTHERN’ HEMISPHERIC CLIMATIC SIGNALS?   总被引：2，自引：0，他引：2  

D.E. SUGDEN  M.J. BENTLEY  C.J. FOGWILL  N.R.J. HULTON  R.D. McCULLOCH  R.S. PURVES 《Geografiska Annaler: Series A, Physical Geography》2005,87(2):273-288

ABSTRACT. This paper examines new geomorphological, chronological and modelling data on glacier fluctuations in southernmost South America in latitudes 46–55°S during the last glacial–interglacial transition. Establishing leads and lags between the northern and southern hemispheres and between southern mid‐latitudes and Antarctica is key to an appreciation of the mechanisms and resilience of global climate. This is particularly important in the southern hemisphere where there is a paucity of empirical data. The overall structure of the last glacial cycle in Patagonia has a northern hemisphere signal. Glaciers reached or approached their Last Glacial Maxima on two or more occasions at 25–23 ka (calendar) and there was a third less extensive advance at 17.5 ka. Deglaciation occurred in two steps at 17.5 ka and at 11.4 ka. This structure is the same as that recognized in the northern hemisphere and taking place in spite of glacier advances occurring at a time of high southern hemisphere summer insolation and deglaciation at a time of decreasing summer insolation. The implication is that at orbital time scales the‘northern’ signal dominates any southern hemisphere signal. During deglaciation, at a millennial scale, the glacier fluctuations mirror an antiphase 'southern’ climatic signal as revealed in Antarctic ice cores. There is a glacier advance coincident with the Antarctic Cold Reversal at 15.3–12.2 ka. Furthermore, deglaciation begins in the middle of the Younger Dryas. The implication is that, during the last glacial–interglacial transition, southernmost South America was under the influence of sea surface temperatures, sea ice and southern westerlies responding to conditions in the 'southern’ Antarctic domain. Such asynchrony may reflect a situation whereby, during deglaciation, the world is more sensitized to fluctuations in the oceanic thermohaline circulation, perhaps related to the bipolar seesaw, than at orbital timescales.  相似文献   

Glacial isostatic adjustment on 3-D Earth models: a finite-volume formulation   总被引：3，自引：0，他引：3  

Konstantin Latychev  Jerry X. Mitrovica  Jeroen Tromp  Mark E. Tamisiea  Dimitri Komatitsch  Christina C. Christara 《Geophysical Journal International》2005,161(2):421-444

  相似文献   

云南点苍山冰川湖泊沉积物磁化率的影响因素及其环境意义   总被引：2，自引：0，他引：2       下载免费PDF全文

杨建强  崔之久  易朝露  张威  刘克新 《第四纪研究》2004,24(4):591-597

文章通过对点苍山海拔3820m冰水沉积剖面的粒度参数、磁化率、氧化铁含量和有机质含量的综合实验分析,并讨论了这些指标的相互关系及其环境意义。实验结果表明,磁化率的强度与粗砂组分的含量成正相关,而与粘土等细粒组分含量成负相关;同时与有机质含量成负相关,与氧化铁含量成正相关。矿物组分分析实验表明,沉积物主要磁性来源于磁化铁。根据以上结果,结合冰川湖泊流域面积小、高寒环境的特点,其磁化率的影响因素与一般湖泊不同,认为冰川湖泊沉积中,因为物源较近导致外源磁性矿物主要赋存于粒度较粗的碎屑颗粒中,而高寒的环境条件使得有机质对沉积物的磁性矿物起到了稀释的作用,而很难有积极的贡献。根据磁化率的环境意义,恢复了全新世以来点苍山的古气候,从中可以划分6个不同的气候阶段:11.5～10.6kaB.P.,10.6～8.9kaB.P.,8.9～5.5kaB.P.,5.5～3.3kaB.P.,3.3～0.8kaB.P.和0.8kaB.P.至今,代表了末次冰期结束以后湖泊从产生至消亡的全过程。根据与其他相关地区的对比,分析了西南季风演变的一些规律。  相似文献