中国南方存在印支期的油气藏——Re-Os同位素体系的制约  

Indosinian Hydrocarbon Accumulation in South China:A Re-Os Isotope Constrain

作　　者：陈玲[1,2] 马昌前[1,2] 凌文黎[1,2] 佘振兵[1,2] 陈子万[1,2] 

机构地区：[1]中国地质大学地球科学学院,武汉430074 [2]中国地质大学地质过程与矿产资源国家重点实验室,武汉430074

出　　处：《地质科技情报》2010年第2期95-99,共5页Geological Science and Technology Information

基　　金：中国石油化工股份有限公司研究项目(P07014);科技部国际合作与交流专项(20071077);国家自然科学重点基金项目(40334037)

摘　　要：利用Re-Os同位素方法开展富含有机质的沥青、原油等的研究,是确定油气成藏时间和破坏时间有效的但极富挑战性的新途径,在国内尚无研究实例报道。以我国南方最大的古油藏之一的麻江古油藏中的沥青为主要对象,采用Re-Os同位素方法试图限定油气的成藏时间和破坏时间。研究表明,麻江古油藏的固体沥青Re、Os同位素质量分数分别在41.5×10-6～642×10-6和0.21×10-6～12.15×10-6之间,N(187Re)/N(188Os)比值较高,且变化范围较大,在270.90～4074.99之间,Os同位素组成指示中等放射成因,其N(187Os)/N(188Os)比值在0.3400～3.6557之间变化。所有沥青样品的模式年龄在28～144Ma之间变化,集中在85Ma左右。通过沥青Re-Os同位素研究,结合详细地质资料,认为麻江古油藏的成藏时间为印支期—早燕山期(144Ma之前),而油藏破坏时间为燕山晚期即85Ma左右。Rhenium-Osmium isotope system is a new and challenging method used to determined the hydrocarbon accumulation and date of desdtruction. This paper reports a Re-Os approach to date the hydrocarbon accumulation and destruction time of the Majiang paleo-oil pool,one of the largest paleo-oil reservoirs in South China. The Re and Os contents in the bitumen vary from 41.5×10-6 to 642×10-6 and 0.21×10-6 to 12.15×10-6,respectively. Their 187Re/188Os ratios are characterized by high and variable range of 270.90 to 4 074.99,while their 187Os/188Os ratios are moderately radiogenic,ranging from 0.340 0 to 3.655 7. The Re-Os model ages for the bitumen vary between 28 Ma and 144 Ma,with an average of ~85 Ma. With conbination of the documented geological researches,the paper suggests that the Majiang hydrocarbon deposit should be finally accumulated at ~144 Ma of Indosinian to Early Yanshanian period,and destroyed at ~85 Ma of Late Yanshanian period.

关 键 词：麻江古油藏 油气成藏年代学 沥青 RE-OS同位素 热电离质谱 

分 类 号：TE122.3[石油与天然气工程—油气勘探] P597[天文地球—地球化学]