倒数第二次冰消期西太平洋边缘海地区δ^(13)C值快速负偏事件及其成因  

RAPID CARBON-ISOTOPE NEGATIVE EXCURSION EVENTS DURING THE PENULTIMATE DEGLACIATION IN WESTERN PACIFIC MARGINAL SEA AREAS AND THEIR ORIGINS

作　　者：卢苗安[1] 马宗晋[1] 陈木宏[2] 隋淑珍[3] 

机构地区：[1]中国地震局地质研究所,北京100029 [2]中国科学院南海海洋研究所,广州510301 [3]中国科学院地质与地球物理研究所,北京100029

出　　处：《第四纪研究》2002年第4期349-358,共10页Quaternary Sciences

基　　金：科技部"南沙群岛及其邻近海区综合科学考察"项目 (批准号 :2 0 0 1DIA5 0 0 41 )资助

摘　　要：南海地区NS93- 5柱样在倒数第二次冰消期出现浮游有孔虫壳体δ13C值快速负偏 (幅度达 1 .7‰ ) ,来自世界各大洋的深海记录和来自北美洲、欧洲、中国等地的陆相记录均指示当时存在大体同步的δ13C值变化表明 :倒数第二次冰消期时存在一次全球尺度的δ13C值快速负偏事件 ,δ13C值在约 0 .1 31MaB .P .达到负偏极值 ,其负偏幅度多在 0 .5‰～ 1‰ ,局部地区负偏幅度 >2‰。当时δ　1 3C值的变化呈突然快速负偏、而后指数曲线状缓慢回返 ,而且δ　1 3C值的突然快速负偏对应大气甲烷浓度快速增加、全球快速升温及冰盖开始快速消融等特点 ,表明大洋环流格局的变化引起海底天然气水合物突然失稳分解并释放大量甲烷可能是其直接成因 ,释放地点推测是在西太平洋边缘海地区。A rapid carbon-isotope ( δ 13 C) negative excursion with an amplitude of 1.7‰ was discovered in a planktonic foraminifera of the penultimate deglaciation age from core NS93-5 in the South China Sea. Similar rapid δ \ 13 C negative excursion was also seen in deep sea records from all world oceans and in terristrial records from North America, Europe and China, showing that the rapid δ 13 C negative excursion event during the penultimate deglaciation is a global scale event. The δ 13 C value reached minimum at about 0.131MaB.P., and most of the excursion amplitude range from 0.5‰ to 1‰,with some locally reported to be more than 2‰. In this event the value of δ 13 C firstly dropped sharply and then recovered slowly in a exponential curve. The rapid decrease of δ 13 C value corresponded to rapid increase of atomosphric methane concentration, rapid global warming and rapid melting of ice-caps. All these indicate that this event could be directly caused by sudden release of a great amount of methane, which was resulted from the sudden decomposition of deep-sea gas hydrate caused by change of ocean current regimes. The release location of methane was suspected to be at West Pacific marginal sea areas.

关 键 词：倒数第二次冰消期 甲烷 天然气水合物 更新世 碳同位素 成因 有孔虫壳体 大洋环流 

分 类 号：P534.631[天文地球—第四纪地质学]