深海沉积物^(10)Be记录研究  

^(10)Be IN DEEP SEA SEDIMENTS

作　　者：沈承德[1] 

机构地区：[1]中国科学院广州地球化学研究所,广州510640

出　　处：《第四纪研究》1997年第3期203-210,共8页Quaternary Sciences

基　　金：国家自然科学基金

摘　　要：DSDP519钻孔^(10)Be测定结果表明，在B／M，M／G两地磁极性倒转期间，^(10)Be产生率均约增加20％。DSDP519孔δ^(10)Be曲线与DSDP502孔δ^(18)O曲线具有明显的正相关关系。CT85－5钻孔^(10)Be曲线在34000±3000aB．P存在明显的峰，峰值比正常值高出2．5倍，~9Be，Zn变化曲线中均未观察到此峰，与Vostok冰芯^(10)Be峰在时间上属于同期。这进一步说明了此时期内^(10)Be浓度增加是全球性的，只能归因于^(10)Be产生率的增加。Raisbeck峰讯号可以成为某些储存库精确时标。DSDP Site 519 is located in the central South Atlantic, 26°8.20′S, 11°39.97′W with water depth 3 769m. ^(10)Be - CaCO_3, correlation of DSDP site 519 shows that ^(10)Be is carried mainly by the non - CaCO_3 phases of the sediments, such as clay minerals and feldspars. There is a positive correlation with regressive coefficient 0.85 between ^(10)Be and ~9Be in the sediments of DSDP519. The average value of ^(10)Be / ~9Be is about 5 × 10^(-8) within the range of ^(10)Be / ~9Be ratio for deep ocean water. ^(10)Be and ~9Be come close to a constant equilibrium between the deep ocean water and sinking sediment particles. Relative increases of 20% of ^(10)Be / ~9Be ratio are observed in the vicinity of the geomagnetic reversals, B / M and M / G. There is a reasonable good positive cormlation between δ^(10)Be curve of DSDP site 519 and δ^(18)O curve of DSDP site 502.Higher δ^(10)Be (δ^(10)Be maximum) corresponds to more positive δ^(18)O (δ^(18)O maximum).The ^(10)Be / ~9Be ratio during glacial, i. e. positive δ^(18)O period, are higher than their average value. Three probable hypotheses can be brought forward to explain the glacial to interglacial differences in the beryllium isotope ratio:(1) The variation of solar activity modulate the intensity of cosmic rays impinging on the earth atmosphere,thus altering the ^(10)Be production rate; (2) Changes in erosional input of ~9Be between glacial and interglacial period; (3) The variation in atmospheric cireulation could be responsible for difference in latitudinal ^(10)Be fall out, and changs in oceanic cireulation could result in different distribution of the Be isotopes.Yiou et al. ~[16] and Raisbeck et al. ~[17] reported that the ^(10)Be concentration in Vostok ice core, Antanica, displays an increase by a factor of two at 35 000 a B.P.,which is called Raisbeck Peak Event. There is the peak at 35 000 a B.P. only in ^(10)Be curve but not in SO_4, δ^(18)O, δD curves. The Raisbeck Peak can only be explained by the increase of ^(10)Be production rate. The Me

关 键 词：深海 沉积物 冰芯 铍10 记录研究 

分 类 号：P736.22[天文地球—海洋地质]