云南白锡腊碱性钛铁质辉长岩类与铁氧化物铜金型矿床关系研究  

Relationships between Alkaline Ti-Fe-Rich Gabbros and Iron-Oxide Copper-Gold Deposits in the Baixila Ore District,Yunnan

作　　者：方维萱 杨新雨 郭茂华 柳玉龙 

机构地区：[1]中色地科矿产勘查股份有限公司,北京100012 [2]昆明中色地科矿产勘查有限责任公司,云南昆明650224

出　　处：《大地构造与成矿学》2013年第2期242-261,共20页Geotectonica et Metallogenia

基　　金：科技部"东川-易门铜矿矿山深部及外围勘查技术研究"课题(编号:2006BAB01B09);"铁氧化物铜金型矿床元素赋存状态及岩相构造学填图技术研发"(编号:2011EG115022);昆明中色地科研发项目(编号:KZSDK-2007-3)资助

摘　　要：云南东川白锡腊铁铜矿段深部碱性钛铁质辉长岩类具有明显的岩相学分带,最新发现的铁氧化物铜金型(IOCG)矿体受碱性钛铁质辉长岩类与隐爆角砾岩相带控制。地球化学研究显示本区碱性钛铁质辉长岩-碱性钛铁质闪长岩具有贫硅、富碱、高磷、富钛铁特征,富集大离子亲石元素(LILE)、稀土元素(REE)及高场强元素(HFSE),与洋岛玄武岩(OIB)类特点一致,具有富铁地幔源区特征。锆石SHRIMP U-Pb年龄揭示它们形成时代为1067±20 Ma^1047±15 Ma,揭示了本区碱性钛铁质辉长岩类和铁氧化物铜金型矿床形成时代为中元古代末期,属于格林威尔同造山期形成的产物。推测这种碱性钛铁质辉长岩类的岩浆源区属板内洋岛玄武岩(OIB),地幔流体交代作用导致上涌侵位,这种富铁地幔源区为区域上大规模铁铜金属超量聚集,提供了良好的成矿动力学条件和丰富成矿物质,不但有利于大型-超大型铁氧化物铜金型矿床形成,而且有利于钛铁矿和铜硫化物(铂钯)富集成矿。Low-Ti iron oxide Cu-U-Au-REE deposits commonly consist of low-titanium iron ore containing variable amounts of copper,uranium,gold,and rare earth elements. However,high-Ti iron oxide Cu-Au-Ag-REE deposits were found in Yunnan and Sichuan provinces,southwestern of China. Based on petrography,geochemistry of major and trace elements,and zircon U-Pb dating,we delineated the relationships between the alkaline Ti-Fe-rich gabbros and the IOCG deposit found recently in the Baixila ore district in Yunnan province,China. Firstly,petrofacies-logging for the gabbros were done in detail for the No. 59,179,and 219 exploration profiles at the 2360m-shafts underground in the Baixila ore district in order to study the gabbros hosting the IOCG or otherwise. Secondly,lithofacies analysis and re-mapping were completed in office study based on the new comprehensive study methods,which include geochemical lithofacies for the rocks and ores,trace element concentrations,and mineralogy of the artificial heavy-mineral-concentrates. Thirdly,the zircons were separated from the gabbros in the Baixila ore district,and then,CL images were used to identify the metamict zircons( ZS02,ZS03 and ZS04) and pristine zircons( ZS01) from the gabbros in the Baixila ore district. Finally,SHRIMP zircon U-Pb dating was carried out.Alkaline Ti-Fe-rich gabbros in the Baixila ore district in Yunnan province,which are closely related to the iron-oxide copper-gold( IOCG) deposits,are obviously lithofacies zonated. On the contrary,the barren alkaline Ti-Fe-rich gabbros are lack of petrofacies zonation. In fact,the iron-oxide copper-gold deposit found recently was controlled by the alkaline Ti-Fe-rich gabbros with obvious lithofacies zonation,and particularly the cryptoexplosion breccia of the gabbros.The alkaline Ti-Fe-rich gabbros are characterized by low Si,and high alkaline,P,Ti-Fe,LILE,REE,and HFSE,which are similar to those of the OIBs derived from the Fe-rich mantle source. It may be supposed that the alkaline Ti-Fe-rich gabbros in this study area could

关 键 词：云南 白锡腊矿段 碱性钛铁质辉长岩 铁氧化物铜金型(IOCG)矿床 板内洋岛玄武岩 富铁地幔源区 

分 类 号：P611[天文地球—矿床学]