鄂尔多斯盆地长7优质烃源岩的岩石学、元素地球化学特征及发育环境  

Petrology and element geochemistry and development environment of Yanchang Formation Chang-7 high quality source rocks in Ordos Basin

作　　者：张文正[1] 杨华[2] 杨奕华[1] 孔庆芬[1] 吴凯[1] 

机构地区：[1]中国石油天然气股份有限公司长庆油田分公司勘探开发研究院,陕西西安710021 [2]中国石油天然气股份有限公司长庆油田分公司,陕西西安710021

出　　处：《地球化学》2008年第1期59-64,共6页Geochimica

基　　金：国家自然科学基金(40773028);国家重点基础研究发展计划项目(2003CB214600)

摘　　要：鄂尔多斯盆地延长组长7优质烃源岩(油页岩)井下岩芯外观呈黑色、质硬、手感较轻,露头风化后呈纸片状。岩石薄片镜下观测和电镜-能谱测试显示,长7优质烃源岩呈纹层状有机质十分发育、莓状黄铁矿丰富-极丰富和胶磷矿丰富的特征,常见晶屑、凝灰质纹层。测试结果显示,长7优质烃源岩岩石化学组成以高二价硫、高Fe、高P2O5和相对较低的Al2O3、SiO2、CaO和MgO为特征,微量元素表现出Mo、Cu、U显著正异常,V、Pb呈正异常,其他微量元素为正常和亏损,总稀土含量(∑REE)较低的特征。较低的Sr/Ba比值和较低的B含量反映了含盐度不高的陆相湖盆沉积特征。高的V/(V+Ni)比值、很高的U/Th比值等指示了沉积环境缺氧的属性。The core of Yanchang Formation Chang-7 high quality source rock （oil shale） is black, hard, light, and it looks slip-shape after demorphism. Rock slice observation and SEM-energy spectrum test show that the Chang-7 high quality source rocks are characterized by the extraordinary development of organic matter laminas, being rich in framboidal pyrite and abundant cellophane, and crystal fragment and tuff laminae are often observed. Comprehensive test results reveal that the chemical compositions of Chang-7 high quality source rock are characterized by high S2-, Fe, P2O5 contents and relatively low Al2O3, SiO2, CaO and MgO contents. In trace elements, Mo, Cu and U are obviously positive anomalies, V and Pb are positive anomalies, and the others are no or negative anomalies. ∑ REE is low. Low Sr/Ba ratios and B content reflect nonmarine lake-basin deposition feature with little salinity. Some geochemical parameters, such as high V/（V ＋ Ni） and very high U/Th ratios, indicate anoxic sedimentary environment.

关 键 词：岩石学特征 微量元素地球化学 优质烃源岩 延长组 鄂尔多斯盆地 

分 类 号：P593[天文地球—地球化学]