东营凹陷湖相烃源岩TOC与Sr的正相关性及原因  

Positive correlation between contents of TOC and Sr in source rocks of the Palaeogene Shahejie Formation in Dongying Sag,eastern China

作　　者：朱光有[1] 金强[2] 张水昌[1] 王冠民[2] 梁英波[1] 

机构地区：[1]中国石油勘探开发研究院,北京100083 [2]中国石油大学(华东)地球资源与信息学院,山东东营257061

出　　处：《地学前缘》2005年第4期551-560,共10页Earth Science Frontiers

基　　金：国家自然科学基金资助项目(40272061);国家"十五"重大科技项目(2001BA605A09);中国石油中青年创新基金项目(04E7052)

摘　　要：古近系沙河街组沙三段是东营凹陷的主力烃源岩。沙三段下部优质烃源岩常常呈纹层结构,主要由富有机质的碳酸盐纹层和粘土纹层组成。通过对其沉积环境和地球化学研究,发现烃源岩有机碳含量(TOC)与微量元素锶(Sr)含量具有显著的正相关关系,而且发现Sr赋存在碳酸盐纹层中,粘土纹层中Sr含量较低。碳酸盐纹层常常主要是由藻类勃发形成的钙质鳞板等内生成因碳酸盐薄纹层组成,因此Sr的来源与藻类勃发有关。藻类勃发对水体化学元素的吸附和同化作用诱发碳酸盐薄纹层形成,Sr占据Ca的晶格位置而在CaCO3中富集,从而在烃源岩中出现TOC与Sr同步富集。The third member of the Shahejie Formation of the Eogene （Es3） is the main source rock of the Dongying Sag, eastern China. The high-quality source rocks of the lower formation of Es3, usually with laminated structure, are primarily composed of carbonate laminas and clay laminas with rich organic matter. From a study of their sedimentary environment and geochemistry, it is found that there are obvious positive correlation between the contents of total organic carbon （TOC） and microelement-Sr existing in these source rocks. In addition, it has been found that the Sr is primarily accumulated in the carbonate laminas rather than in the clay laminas. Because the carbonate laminas are usually composed of endogenetic thin laminas of carbonate, such as calcareous imbricate plank formed by algal blooming, it is concluded that the source of Sr has a relation to algal blooming. The thin carbonate laminas are formed because of the absorption and assimilation of chemical elements in water during algal blooming. Sr occupies the crystal lattice sites of Ca, and then accumulates in CaCO3, resulting in the synchronous enrichment of TOC and Sr in these ources rocks.

关 键 词：烃源岩 SR 有机碳 藻类勃发 东营凹陷 

分 类 号：TE122.113[石油与天然气工程—油气勘探]