云南金顶超大型铅锌矿床沥青Re-Os法测年及地质意义  

Re-Os dating of bitumen in the giant Jinding Zn-Pb deposit,Yunnan and its geological significance

作　　者：高炳宇[1] 薛春纪[1] 池国祥 李超[3] 屈文俊[3] 杜安道[3] 李足晓[1] 顾浩[1] 

机构地区：[1]地质过程与矿产资源国家重点实验室,中国地质大学地球科学与资源学院,北京100083 [2]Department of Geology,University of Regina,Regina,Saskatchewan S4S0A2,Canada [3]国家地质实验测试中心,北京100037

出　　处：《岩石学报》2012年第5期1561-1567,共7页Acta Petrologica Sinica

基　　金：国家重点基础研究计划(2009CB421005);国家自然科学基金(40930423;41072069;40772061);国土资源部公益性行业科研专项(200911007-23);长江学者和创新团队发展计划(IRT0755);高等学校学科创新引智计划(B07011)联合资助

摘　　要：油气藏与金属矿床在世界许多沉积盆地内共存,油气成藏与金属成矿的动力学关系备受关注。云南兰坪金顶产有中国目前最大铅锌矿床,也是世界上唯一陆相沉积岩容矿、且形成于新生代的超大型铅锌矿床。矿床中常见沥青、重油等有机质,它们的形成早于或晚于铅锌硫化物成矿存在明显分歧,限制了对油气成藏与铅锌成矿关系的认识。本文针对金顶超大型矿区以古新统云龙组含砾砂岩和砂砾岩为主岩铅锌矿石中沥青,开展了Re-Os法同位素测年,获得68±5Ma的等时线年龄(MSWD=9.2,n=6),指示金顶古油气成藏形成于古新世,先于铅锌硫化物大规模成矿;烃类物质具有通过热化学还原硫酸盐提供铅锌成矿所需硫化氢的客观条件;油气成藏与铅锌成矿在云南金顶矿区很可能是一个先后发生的连续地质过程,成藏为成矿奠基,成矿伴随着油气藏的破坏。Oil-gas reservoirs and metal deposits often co-exist in many sedimentary basins,and their genetic relations have been paid much attention.The Jinding Zn-Pb deposit,Yunnan,China,is so far the largest Zn-Pb deposit in China,the youngest and only giant Zn-Pb deposit hosted in continental sedimentary rocks in the world.Bitumen and heavy oil were often observed in the Jinding ZnPb deposit.It has been a subject of debate whether the bitumen formed before or after the Zn-Pb mineralization,making it difficult to evaluate and the genetic relationship between the bitumen and Zn-Pb mineralization.The bitumen in the Jinding Zn-Pb ores hosted in the breccia-bearing sandstones and sandy breccias of the Paleocene Yunlong Formation has been dated by the Re-Os method in this paper,and an isochron age of 68 ± 5Ma（MSWD = 9.2,n = 6） has been obtained.Therefore,the oil-gas reservoir in the Jinding ore district was formed earlier than the Zn-Pb mineralization.The hydrocarbons in the reservoirs may have provided the condition for the production of reduced sulfur required for Zn-Pb mineralization through thermal chemical reduction of sulfates.The formation of the oilgas reservoir and the Zn-Pb deposit may have been a continuous geologic process,and the oil-gas reservoir was one of the basic conditions of Zn-Pb mineralization in the Jinding ore district.The oil-gas reservoir was destructed by the mineralization process.

关 键 词：砂砾岩容矿铅锌矿石 沥青 RE-OS同位素测年 金顶超大型铅锌矿床 云南兰坪 

分 类 号：P597.3[天文地球—地球化学]