撞击事件对古环境的影响——来自ODP1144站A孔样品的证据  

IMPACT EVENTS AND ITS EFFECTS ON PALAEOENVIRONMENT: EVIDENCE FROM ODP SITE 1144 CORE A

作　　者：刘建忠[1] 张蕾[2] 李春来[1] 王世杰[2] 邹永廖[1] 徐琳[2] 欧阳自远[1] 

机构地区：[1]中国科学院国家天文台,北京100012 [2]中国科学院地球化学研究所,贵阳550002

出　　处：《第四纪研究》2002年第6期552-557,共6页Quaternary Sciences

基　　金：国家自然科学基金 (批准号 :4 97732 0 4 )资助项目;中国科学院知识创新工程项目 (批准号 :KZCX2 - 115 );中国科学院高技术与发展局专项项目 (批准号 :KGCX2 - 4 0 6 )

摘　　要：本文通过对ODP114 4站A孔B M界线附近样品中微玻璃陨石的挑选和研究 ,确定在中更新世曾发生过地外物体撞击地球的灾变事件。样品中浮游有孔虫壳体碳氧同位素的对比研究表明 ,在微玻璃陨石事件发生的后期 ,曾发生了浮游有孔虫壳体碳氧同位素组成的变化 ,表现为δ13 C值的降低和δ18O值的增加。文中还探讨了其形成的原因。The study on microtektites of Ocean Drilling Project(ODP) site 1144 core A around Brunhes/Matuyama boundary indicated the impact event had happened in mid Pleistocene. In this paper we use shell of foraminifera G.sacculifer to determine their C and O isotope compositions. The results indicate that C and O isotope components had changed( δ 13 C reduced and δ 18 O ascend) in the late stage of microtektite event. The main reason of changes of C and O isotope components is because a part of target rock can be melted and boil away by huge energy when exterrestrial object shocked the Earth so the oxygen( δ 18 O) and carbon( δ 13 C) isotope composition of atmosphere can be transferred and in the mean time a large of clastic debris and shocking dust can be displaced into stratosphere and diffused to the seven seas. These clastic debris and shocking dust can reduce radialization of the sun and result in the temperature and photosynthesis reduced, so biologic acts weakened and amount of CO 2 decreased. In relative to carbon( δ 13 C) isotope composition,the oxygen( δ 18 O) isotope composition is ascend.

关 键 词：撞击事件 古环境 浮游有孔虫壳体 灾变事件 碳同位素 氧同位素 

分 类 号：P531[天文地球—古生物学与地层学]