西藏嘎拉勒铜金矿床“镁质矽卡岩”或“超镁铁质岩”的厘定与成因探讨  

Determination and genesis of“magnesian skarn”or“ultramafite”of Galale Cu-Au deposit in Tibet,China

作　　者：张志[1] 唐菊兴[2] 王立强[2] 姚晓峰[3] 王红星[1] 宋俊龙[1] 杨毅[1] 胡正华[1] 

机构地区：[1]成都理工大学地球科学学院,成都610059 [2]中国地质科学院矿产资源研究所,北京100037 [3]中国地质调查局发展研究中心,北京100037

出　　处：《成都理工大学学报（自然科学版）》2015年第2期159-168,共10页Journal of Chengdu University of Technology: Science & Technology Edition

基　　金：国家自然科学基金资助项目(41172077);国家重点基础研究发展规划"973"项目(2011CB403103);国土资源部公益性行业科研专项(201011013-3)

摘　　要：嘎拉勒铜金矿床是班公湖-怒江成矿带南缘碰撞期成矿事件的代表性矿床,其金资源量达到大型以上规模。鉴于在矿床勘查中对矿床成因的不同认识导致找矿勘查理论及找矿方向的差异,作者从矿床成因立足之本的"镁质矽卡岩"与"超镁铁岩"的厘定出发,重点研究了这类岩石的岩石学以及岩石地球化学特征。主元素方面,"超镁铁岩"与白云岩及花岗闪长岩之间具有明显的接触双交代特征;痕量元素具有负Ba、K、Ti异常,富集Rb、U、Th等大离子亲石元素,亏损Hf、Ti等高场强元素的特征;稀土元素表现为轻重稀土分馏明显,轻稀土明显陡倾的配分形式。痕量元素与稀土元素地球化学特征与区域上与蛇绿岩套有关的镁铁质岩地球化学特征严重不符,而与白云岩及花岗闪长岩之间具有密切的亲缘性及继承性。综合研究表明,前人所谓"超镁铁岩"应为接触交代成因镁质矽卡岩,矿床为接触交代矽卡岩型铜金矿床。The Galale copper-gold deposit is the typical deposit of the collisional mineralization events on the southern margin of the Bangonghu-Nujiang metallogenic belt in Tibet.Its gold resources has reaches more than that of a large-scale deposit.In view of the differences in exploring theory and prospecting direction led to by the different views on the genesis of the deposit in exploring deposits, this paper gives emphasis to studying the characteristics of petrology and geochemistry based on the＆amp;nbsp;determination of the “magnesian skarn”and “ultramafite rock”.The research result shows that there are obvious characteristics of dual contact metasomatism among the “ultramafite rock”and dolomite and granodiorite in the aspect of the major elements.Trace elements show the characteristics of having Ba,K,Ti negative anomalies,enriching Rb,U,Th etc.,and losing Hf,Ti of high field strength elements;REE shows that LREE and HREE fractionation is obvious and the LREE is apparent tilt partition.Trace elements and REE geochemical characteristics are seriously inconsistent with that of the ultramafite rock related to ophiolite regionally.On the contrary,trace elements and REE have a close affinity and inherited characteristics with dolomite and granodiorite. The comprehensive studies show that the previous so-called “ultramafite rock”is the contact metasomatic“magnesian skarn”,and the deposit is the contact metasomatic copper-gold skarn deposit.

关 键 词：镁质矽卡岩 超镁铁质岩 矿床成因 西藏 

分 类 号：P588.312[天文地球—岩石学]