青海湖湖底沉积物中的有机质

STUDY ON ORGANIC MATTERS IN THE SEDIMENTS FROM THE BOTTOM OF THE QINGHAI LAKE,CHINA

盐湖沉积环境是烃源岩发育的重要地质环境。对青海湖沉积物中有机质、族组分及饱和烃进行测试分析发现,湖体底部水体和浅层沉积物处于弱氧化环境,沉积物中总有机碳含量较高,有机质具陆源高等植物和湖内低等菌藻类复合来源。热演化程度极低的青海湖湖底沉积物中碳数分布、主峰碳、碳优势指数(CPI)、姥鲛烷/植烷(Pr/Ph)等参数与我国典型咸化湖环境成熟烃源岩及其生成的原油中相应参数的对比,提供了一套未成熟有机质基本参数的参考值,有利于正确利用这些参数分析有机质的成熟度。

Saline lake is one of the most favorable environments for developing hydrocarbon source rocks. Analyzing the group components and the saturate hydrocarbons in organic matters in the sediments from the bottom of the Qinghai Lake shows that the contents of total organic carbon in the sediments is high and that the sedimentary environment at the bottom of the Qinghai Lake is feeble oxidative. The organic matters mainly originate from the higher terrigenous plants around the Lake and the microbes and algaes in the Lake. Comparing the parameters such as distribution of carbon amount, carbon amount with peak value of content, carbon predominance index（CPI）, and pristane/phytane ratio（Pr/Ph） in the immature organic matters in the sediments from the bottom of Qinghai Lake with those in mature hydrocarbon source rocks and crude oils from the typical salty lacustrine environment in our country can give us a set of valuable reference data about the maturity of organic matters.