摘要
Re-Os同位素定年在石油生成及富有机质沉积岩的绝对定年方面取得了良好的应用效果,并且石油的Os同位素初始值还可以作为油源示踪的指标。分析了Re-Os同位素定年方法在富有机质体系中应用的原理,探讨了影响同位素体系封闭性的各种因素,指出熟化作用、生物降解及水洗作用、脱沥青作用不会影响Re-Os同位素体系的封闭性,而硫酸盐热化学还原作用、成矿流体作用及幔源岩浆混染会扰动Re-Os同位素体系。目前石油系统中Re-Os同位素研究存在的主要问题可归结为2个方面:1石油系统有机质中Re-Os同位素的地球化学行为;2Re-Os同位素年龄的精度及其指示意义。对于这2个方面,开展有机相及现代海藻与Re-Os同位素相关性的研究将有助于了解Re和Os在有机质中的具体富集形式;对控制Re-Os同位素分馏的因素(如沉积环境及有机质类型)的研究将会有助于鉴别哪些地层以及什么样的样品能用来进行Re-Os定年。
Re-Os isotope geochronometer has achieved a lot in getting absolutely precise ages of petroleum generation and Organic-Rich Sedimentary（ ORS） rocks. And what＇s more,the initial187 Os /188 Os ratios can be utilized as an oil to source fingerprinting tool in the oil-source correlation. This paper analyzed the principles of ReOs isotope dating methods applied in Organic-Rich Sedimentary systems,and discussed the various factors of influences on the Re-Os isotope system. Those geological processes such as the maturation of hydrocarbon,biodegradation and water washing and the progressive precipitation of petroleum asphaltenes had very little effect on Re-Os isotope system. However,Re-Os isotope system could be disturbed by Thermochemical Sulfate Reduction（ TSR）,hydrothermal fluid and the contamination of mantle-fluid. The main problems of the research on Re-Os isotope in petroleum system at present can be attributed to two aspects： 1the understanding of geochemical behavior of Re and Os in organic maters; 2how to get precise Re-Os isotope ages and the interpretation for the ages. In terms of these two aspects,carrying out the research of the relationship between Re-Os data and organic faces and modern algae may help the better understanding of Re-Os geochemical behavior and their enrichment mechanism. The research about the factors（ e. g. depositional environment and organic type） that control Re-Os fractionation may provide a method to know which stratigraphic sections and which samples to utilize for Re-Os geochronology.
出处
《地球科学进展》
CAS
CSCD
北大核心
2015年第2期187-195,共9页
Advances in Earth Science
基金
国家自然科学基金项目“南方典型古油藏沥青来源和形成时代的Re-Os-PGE示踪研究”(编号:41372140)资助
关键词
富有机质沉积岩
熟化作用
生物降解
沉积环境
有机质类型
Organic-rich sedimentary rock
Hydrocarbon maturation
Biodegradation
Sedimentary environment
Organic matter type
