意大利上新世古生产力的轨道驱动  

The Paleoproductivity Forced by Earth Orbital Forcing in Italy During Early Pliocene

作　　者：丁晓辉[1] 王汝建[1] 李建如[1] 黄恩清[1] 

机构地区：[1]同济大学海洋地质国家重点实验室,上海200092

出　　处：《地球科学进展》2007年第10期1019-1026,共8页Advances in Earth Science

基　　金：国家重点基础研究发展计划项目"地球圈层相互作用中的深海过程和深海记录"(编号:G2000078505);国家自然科学基金项目"西太平洋暖池与东亚古环境:沉积记录的海陆对比"(编号:40321603);上海市科委国际合作重点项目"气候长周期变化的新机制:中国和意大利的地质证据";国家高技术研究发展计划项目"大洋钻探技术预研究"(编号:2004AA615030)联合资助

摘　　要：主要研究了意大利上新统3个剖面Punta Piccola、Cape Spertivento以及Punta Rossello蛋白石含量的变化,综合其它古环境指标对非洲季风和地中海表层生产力加以分析,研究表明,PuntaPiccola剖面和Cape Spertivento剖面各古环境指标对岁差周期影响的响应明显而单纯,即岁差低值,对应氧同位素偏负,有机碳和蛋白石高值以及碳酸盐低值,说明地中海表层生产力明显受到岁差的驱动。岁差驱动下的北非夏季风导致尼罗河泛滥,带来的丰富营养元素使得生产力剧增,同时淡水注入,阻碍了水体的垂向交换,直接导致了海底的缺氧环境,硅藻利用深层营养产生勃发,并组成"藻席",快速沉降到海底,使得有机碳迅速埋葬和保存,从而引发了腐泥层的形成。Punta Ros-sello剖面硅藻层证实了"藻席"的存在,但是蛋白石含量并不高。We studied the variability of the African monsoon and the Mediterranean sea surface productivity during the early Pliocene based on the analysis of some paleoenvironment proxies such as planktonic foraminifera oxygen isotope and biogenic compositions（carbonate,biogenic opal and organic carbon） in three profiles respectively,Punta Piccola,Cape Spertivento and Punta Rossello in southern Italy.Our results show that during the early Pliocene,the increase of the Northern Hemisphere summer insolation which is also presented as low precession value is usually correlated to organic carbon and opal increases,carbonate decrease and the negative excursions of stable oxygen isotope.The variability of the proxies implies the sea surface productivity controlled by the precession.Enhanced runoff induced by the strengthened African summer monsoon brings abundant terrestrial nutrients and fresh water into the Mediterranean sea,which conduces to productivity blooming and anoxic condition in the Mediterranean sea bottom.Furthermore,opal thrives herein by using deep-nutrient,buildups mats and decline fleetly into sea bottom so that organic carbon is speedily buried and conserved,thus making the sapropels come into being.Diatom layers in Punta Rossello profile confirm the existence of mats,but the content of opal in some layers is not high.

关 键 词：非洲季风 地中海 古生产力 岁差 上新世 

分 类 号：P534.622[天文地球—古生物学与地层学]