【作者】 汪欢；

【导师】 刘家军；

【作者基本信息】 中国地质大学(北京) ， 矿物学、岩石学、矿床学， 2012， 硕士

【摘要】 陕西双王金矿床是西秦岭地区一个重要的大型金矿床，位于西秦岭东段南麓，夹持于商-丹断裂和凤-镇断裂之间，矿化表现为热液隐爆角砾岩型。本文通过对矿床地质特征，矿区岩浆岩的矿物学、岩石学、地球化学研究以及成矿信息和成岩信息的对比研究获得以下认识：（1）矿区出露最广的岩浆岩为西坝岩体，其具有两期侵入的特点，第一期侵入体为典型的I型花岗质岩石，并且多具有埃达克质岩石的特征，形成时代为218～219Ma，第二期侵入体具有I型和A型花岗质岩石过渡的特征，形成时代为215Ma。Hf-Sr-Nd-Pb同位素特征表明，两期侵入体的成岩物质主要以类似耀岭河群的元古代基底物质为主，并且有起源于地幔的基性岩浆的混入。两期侵入体是在扬子板块和华北板块全面碰撞之后的岩石圈由挤压向拉张转变的环境下批示部分熔融形成的，第一期侵入体的源区残留主要为角闪石和石榴石，形成深度大，而第二期侵入体源区残留主要为角闪石和斜长石及少量的石榴石，形成深度比第一期稍浅。（2）矿区出露的脉岩有花岗斑岩脉、煌斑岩脉、石英钠长岩脉。花岗斑岩形成于印支晚期-燕山早期，为发生了一定分异的I型花岗质岩石，成岩物质为古老的地壳基底物质，其形成于地壳厚度开始发生减薄的环境下，源区残留主要为斜长石和石榴石；煌斑岩形成于燕山期的板内环境中，岩浆源区为受到俯冲带物质脱水形成的流体交代的富集岩石圈地幔，并且岩浆在上侵过程中受到了一定程度的大陆地壳物质混染。石英钠长岩的源区物质可能为下伏的钠质地壳基底物质，其为西坝岩体形成过程中同熔钠质基底物质并经过强烈的分异形成。（3）研究认为双王金矿床形成于印支晚期，与西坝岩体形成时代相近，两者具有密切的时空关系及成因联系，而花岗斑岩和煌斑岩为成矿后岩体，它们与金矿的形成没有成因联系。通过对西坝岩体、围岩地层、蚀变岩石、矿石的物质成分研究结合氢、氧、碳、硫、铅同位素组成表明，成矿金属物质主要来源于赋矿岩石和下伏地层，西坝岩体为金矿的形成提供成矿热液及部分硫、碳、铅，其在上升侵位过程中活化了基底岩石的钠质和碳酸盐，带来了气液隐爆作用所需的大量挥发份并且驱动大量的流体运移。更多还原

【Abstract】 The Shuangwang gold deposit is an impotant large gold deposit occurs in theWest Qinling area. It is located in the South Qinling gold metallogenic belt betweenthe Shangzhou-Danfeng fault and Fengxian-Zhen’an fault.The deposit is hosted inhydrothermal cryptoexplosive breccia. Through systematic study of geologicalfeatures of deposit, mineralogy, petrology, geochemistry of magmatic rocks inShuangwang gold mine, and comparative study between deposit and magmatic rocks,we have figured out the characteristics and genesis of magmatic rocks around themine, revealing the genetic relationship between magmatic rocks and deposit. Someconclusions have been drawn as below:(1) In Shuangwang gold mine, Xiba granitiod as the most widely distributedmagmatic rocks have two periods. The first phase of the intrusions formed in218~219Ma, are typical of I-type granitic rocks and have the characteristics ofadakitic rocks. The second phase of the intrusions formed in215Ma, are transitionalbetween I-type and A-type granites. The Xiba granites have the same source rockswhich mainly consisted by Proterozoic mafic lower crust(such as Yaolinghe group)with some mafic magma derived from partial melting of mantle lithosphere.Thegranitiods were formed in the tectonic environment of transformation fromcompression to extension in the Qinling orogenic belt. The residual mineralassemblage of the first phase intrusions are consist of hornblend and garnet withoutinvolvement of significant amouts of plagioclase, which implies its source region isvery deep. The residuum of the second phase intrusions are horrnblend, plagioclase,and a small quantity of garnet, which indicate a slightly lighter source depth than thefirst.(2) Granite-porphyry formed between Late Indosinian and early Yanshanian aredifferentiation of I-type granitoid rocks. The diagenetic material are the ancient crustalbasement without mantle material. It was formed in the tectonic environment ofthinning of the crustal thickness, the source region residues are mainly plagioclase andgarnet.Lamprophyre dikes formed in the within-plate setting of Yanshanian. Thelamprophyre formed from the magma derived from partial melting of the mantle withmetasomatism of fluids in subduction zone, and with contamination of crustalmaterials in rising process of the magma.(3) Through the geochronology study of other deposits in the region of Fengtai area. We figure out Shuangwang gold deposit formed in the late Indosinian similar tothe age of Xiba granitiod, had a temporal relationships and close genetic link with themagmatism. Granite-porphyry and lamprophyre are post-ore dikes with no geneticrelationship to gold mineralization.According to study of material composition ofXiba granitiod, ore-hosted stratum, altered rocks, and ore, coupled with hydrogen,oxygen, carbon, sulfur, lead isotopic composition, it is reasonably considered thatore-forming materials were mainly derived from country rocks and underlying rocks.Xiba granitiod provided hydrothermal fluid, heat and some ore-forming materials.更多还原