青海赛坝沟金矿辉长岩地球化学组成及成因分析  

Geochemical Composition and Genetic Analysis of Gabbro of Saibagou Gold Deposit,Qinghai Province

作　　者：邢佳 王建国[1,2] 王志男 胡建 魏生云 XING Jia;WANG Jianguo;WANG Zhinan;HU Jian;WEI Shengyun(Department of Geological Engineering,Qinghai University,Xining 810016,Qinghai,China;State Key Laboratory of Mineral Processing Science and Technology,Beijing 102628,China)

机构地区：[1]青海大学地质工程系,青海西宁810016 [2]矿物加工科学与技术国家重点实验室,北京102628

出　　处：《黄金科学技术》2022年第5期664-675,共12页Gold Science and Technology

基　　金：国家自然科学基金项目“基于微观层面分析的岩矿电阻率耦合机理及其模型:以查藏错铜铅锌矿床为例”(编号:42164007);青海省应用基础研究计划项目“柴北缘地区铍矿床成矿约束条件、地质意义及靶区优选”(编号:2019-ZJ-7022);矿物加工科学与技术国家重点实验室开放基金项目“典型金属矿物标型特征及其对可选性的影响”(编号:BGRIMM-KJSKL-2020-04)联合资助。

摘　　要：赛坝沟金矿是位于柴北缘乌兰—都兰战略性金属矿集区的中型金矿床之一,金矿床的形成受断裂系统的严格控制,矿体大多赋存于NW向脆—韧性剪切带内的英云闪长岩和辉长岩中,呈细脉状、分支脉状、不规则状和透镜状产出。赛坝沟金矿区出露的岩浆岩绝大多数为辉长岩类和花岗岩类,其中辉长岩与矿体在产出位置上表现出密切的空间相关性,且在矿区内发育的各类岩浆岩中,辉长岩的金含量远高于其他类型的岩浆岩,对其开展全岩元素分析显得尤为必要。分析结果显示:赛坝沟金矿区的辉长岩以碱性和亚碱性辉长岩为主,岩石全碱含量较高,Na、Al、Sr元素以及轻稀土元素(LREE)相对富集,Nb和Ti等稀有元素相对亏损。综合金矿地球化学特征分析,认为该矿区岩石岩浆起源为岩石圈地幔,在上涌过程中下地壳发生了底侵作用,促使深部初始岩浆房的形成,并在后续侵位到地壳浅部的演化过程中经历了一定程度的同化混染作用和较强的分离结晶作用。The Saibagou gold deposit is one of the medium-size gold deposits located in the Wulan-Dulan strategic metallic ore concentration area in northern Qaidam Basin.The regional tectonic location spans the Tanjianshan magmatic arc,ophiolite melange in the northern Qaidam Basin and Olongbulak microcontinent,and is located at the intersection of Wahongshan-Wenquan fracture and Yuka-Wulan fracture.The formation of the deposit is strictly controlled by the fracture structure.There are two groups of fracture belts in the mining area,namely the NW trending thrust fracture and the NE trending shift fracture,and the gold orebody are mainly developed in the NW brittle-ductile shearing belt in veins,irregular,branched veins and lenticular.The main ore types are structural altered rock type and quartz vein type.Magmatism in the mining area is strong,and the active ages mainly include Late Variscan-Indosinian and Neoproterozoic,especially the Variscan magmatic activity is the most significant.Magmatic rocks exposed in the mining area are mainly gabbro and granite,in which gabbro and ore body have close spatial correlation.The magmatic rock samples used in this study were all taken from fresh gabbro after stripping regolith around the orebody of Saibagou gold deposit.The element analysis of the whole rock was conducted by the Qinghai Nuclear Industry Geological Bureau,including the detection of major elements,trace elements and rare earth elements.The results show that all gabbro in Saibagou gold deposit are tholeiite basalt,mainly alkaline gabbro and subalkaline gabbro,most of which are calcalkaline series or low potassium(tholeiite)series gabbro,and a small amount of shoshonite series gabbro exist.Gabbros are characterized by high total alkali content,enrichment of Na,Al and light rare earth elements,strong enrichment of large ion lithophile elements Sr,and depletion of high field strength elements Nb and Ti.Through in-depth analysis and comparison of the La/Nb and Zr/Ba values,Hake diagram,Rb/Y-Nb/Y ratio diagram,La-La/Sm diagr

关 键 词：岩石圈地幔 地球化学 辉长岩 岩石成因 岩浆起源 赛坝沟金矿 青海省 

分 类 号：P618.51[天文地球—矿床学]