塔里木盆地奥陶系萤石矿和礁滩相油藏耦合关系与成矿模式  

THE COUPLING RELATIONSHIP BETWEEN FLUORITE MINE AND ORGANIC REEF-BANK OIL POOL OF ORDOVICIAN CARBONATES AND METALLOGENIC MODEL OF FLUORITE MINE IN TARIM BASIN

作　　者：周刚[1] 郑荣才[1] 罗平[2] 张兴阳[2] 刘伟[2] 宋金民[2] 饶红娟[3] 

机构地区：[1]油气藏地质及开发工程国家重点实验室(成都理工大学),四川成都610059 [2]中国石油勘探开发研究院,北京100083 [3]贵州省地质矿产勘查开发局101地质大队,贵州凯里556000

出　　处：《矿物岩石》2011年第4期67-76,共10页Mineralogy and Petrology

基　　金：国家重点基础研究发展计划“973”项目(2006CB202300)

摘　　要：塔里木盆地巴楚-柯坪野外露头区和塔中井区奥陶系萤石矿体呈串珠状或沿裂缝呈条带状分布,通过露头岩心、钻井岩心、普通薄片、电子探针、X衍射、阴极发光、流体包裹体和微量元素、稳定同位素分析等方法,对萤石矿及其围岩和油藏进行详细研究,探讨萤石矿和礁滩相油藏耦合关系与成矿模式。萤石矿体富集在礁、滩相灰岩为基岩的与断层相关的部分岩溶洞穴中,和萤石一起共生的矿物还有方解石、重晶石、硬石膏、石英及黑色沥青,萤石中含丰富的液态、气态烃包裹体、固态沥青包裹体和柱条状石膏子晶;萤石的K/Rb和Sr/Ba比值远小于正常海水值,富铕及轻稀土元素而贫重稀土元素,其礁滩相围岩碳、氧同位素具越靠近萤石脉体δ13 C和δ18 O值负偏移越明显特征,萤石相对其围岩具有更高的87Sr/86Sr比值。研究表明塔里木盆地奥陶系萤石矿属于"被动型"密西西比层控矿床,成矿机理为礁滩型"油气藏"转化为"矿捕"作用,具先成藏后成矿、多期成藏多期成矿特点,成矿流体具有盆地油田卤水和深循环大气淡水双重特征的后期低温热液成因性质,成矿物质来源于下寒武统下部黑色硅质岩及磷块岩,不整合面和断层是热液流体及成矿流体运移通道,生物礁滩和区域断层对萤石矿或油藏具有极其重要的"层、相、位"控制作用。According to detailed studies of fluorite mine,their surrounding rocks and oil pool of Ordovician carbonates in Bachu-Kerpin outcrops and drilling wells,Tarim Basin,the coupling relationship between the fluorite mine and oil pool and metallogenic model of fluorite mine have been probed synthetically through different analyses,including drilling core,cast thin section,EPMA,X-ray diffraction,cathode luminescence,fluid inclusion,trace elements and stable isotopes.It is showed that beaded or banded fluorite mine occurred in fault-related karst caves,with reef-bank limestone as their surrounding rocks.Mineral association with fluorite mine includes calcite,barite,anhydrite,quartz and black asphalt et al.Fluorites possess gas-liquid-rich hydrocarbon inclusion,solid bitumen inclusion and columnar gypsum whiskers.Analysis of fluorite trace elements with enrichment of Eu and LREE and weak HREE indicates that the ratio of K/Rb and Sr/Ba is much lower than that of normal seawater.The negative drift of δ13C and δ18O in the surrounding rocks is more and more obvious when the country rocks is approaching the fluorite,and the ratio of fluorite 87Sr/86Sr is higher than that of its surrounding rocks.It was proved that the type of Ordovician fluorite mine in Tarim basin belongs to Mississipp-type stratabound deposit and lithologic reservoirs.Its formation mechanism was characteristic of initial reef bank-type reservoir followed by transformed into fluorite ore deposit,evidenced by hydrocarbon accumulation before ore accumulation and multi-phase hydrocarbon accumulation and mineralization.The geochemical results of fluorite and its surrounding rocks showed that the metallogenic fluids have double natures of the later low-temperature hydrothermal fluids of basin oilfield brine and deep meteoric water,and the metallogenic sources came from the underlying dark siliceous rocks and phosphorite of the Lower Cambrian.The migration path of the hydrothermal fluids and metallogenic fluids were the unconformity and faults.Reef-bank and regi

关 键 词：生物礁滩 油藏 萤石矿 层控矿床 塔里木盆地 

分 类 号：P619.215[天文地球—矿床学]