Re-Os同位素测年法在油气成藏年代学的研究进展  

Advances in Re-Os Isotopic Dating in Geochronology of Hydrocarbon Accumulation

作　　者：蔡长娥[1,2] 邱楠生[1,2] 徐少华[1] 

机构地区：[1]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249 [2]中国石油大学(北京)盆地与油藏研究中心,北京102249

出　　处：《地球科学进展》2014年第12期1362-1371,共10页Advances in Earth Science

基　　金：国家自然科学基金杰出青年科学基金项目"石油与天然气地质学"(编号:41125010)资助

摘　　要：铼—锇(Re-Os)同位素应用于油气成藏年代学是近10年来的一个前沿领域,在国际上已取得了重要成果,目前国内对此方法的应用还较缺乏。利用Re-Os同位素测年法开展页岩或沥青等富有机质沉积岩的研究,可以精确厘定油气运移和充注时间,也可以有效示踪烃源岩。在阅读国内外大量文献的基础上,概述了Re-Os同位素定年原理,分析了海水—沉积物中Re和Os元素的富集过程,总结了Re-Os同位素测年的测试对象、样品准备和分析测试方法。指出初始187Os/188Os比值不仅可以限定油气生成和油气充注的年龄,还可以有效评价源—油关系;放射成因的187Os/188Os比值与烃源岩年龄呈正相关。认为烃类成熟度、生物降解作用和水洗作用不足以造成Re-Os等时线图中出现离散点,而初始187Os/188Os比值变化、沉积后Re和Os的流动性和硫酸盐热化学还原作用是引起Re-Os等时线图中出现离散点的3个主要原因。Re-Os年龄的重现性和准确性与样品颗粒的大小及取样量密切相关。相对于其他同位素测年法,Re-Os同位素测年法的最大优势在于对直接参与油气成藏的地质体进行研究,可以得到油气成藏期的直接证据。最后探讨了现阶段ReOs同位素体系研究中尚存在的问题,就未来研究热点和发展方向做出展望,以期能有效推动Re-Os同位素定年相关的理论和技术的深入发展。Rhenium-Osmium （Re-Os） isotopic dating applied to the geochronology of hydrocarbon accumula- tion has been the forefront of international research in the last 10 years and has achieved significant achievements. However, our current researches are lacking in Re-Os isotopic chronology on the geochronology of hydrocarbon ac- cumulation. The successful application of the Re-Os geochronology has enabled the determination of accurate and precise depositional ages for Organic-Rich Sedimentary rocks （ ORS）, the establishment of timing constraints of oil generation or migration, and the fingerprinting of the source of oil. On the basis of literatures study both at home and abroad, this article mainly dealt with the principle of Re-Os isotopic dating and analyzed the accumulation processes of Re and Os in a seawater-sediment system. Meanwhile, the test samples, sample preparation and ana- lytical methodology of Re-Os isotopic dating were summarized. The results revealed that the initial lSTOs/lSSOs ratio could constrain the age of oil generation or migration, and effectively evaluated the relationship between source rock and oil. The radiogenic 187Os/188Os ratio showed a positively correlated relationship with source rock age. This arti- cle proposed that hydrocarbon mature, biodegradation and water washing had minimal or no effect on data scatter a- bout Re-Os isochron. However, the effects of postdepositional mobility of Re and Os, variations in the initial 187Os/1880s ratio, and thermoehemical sulfate reduction could result in data scatter. The reproducibility and accura- cy of Re-Os age was also closely related to the sample particle size and sample amount. Compared with other isotop- ic dating, the biggest advantage of Re-Os isotopic dating is to study geological body related to accumulation process, and to obtain direct evidence of hydrocarbon accumulation period. From what was discussed above, the ar- ticle discussed the existing problems and put forward the future hot research and development direction of R

关 键 词：放射性年龄 187Os/188Os比值 硫酸盐热化学还原作用 

分 类 号：P579[天文地球—矿物学]