赞比亚铜带省铜矿成因分析

中非(赞比亚―刚果(金))沉积型铜矿以其拥有高品位的大型超大型铜、钴矿床和众多的世界级铜矿山而闻名于世。铜矿类型可分为沉积型铜矿、热液脉型铜矿、变质热液型铜矿三类。沉积型铜矿床形成后,受到深部含矿岩浆热液的侵入形成脉状铜矿,可能还有斑岩型铜钼矿的成矿作用,叠加富集原有的沉积型铜矿床。硫同位素结果显示,硫源主要为成岩硫化物和海水硫酸盐的混合硫,受到深源岩浆或岩浆热液叠加改造。沉积型铜矿成矿年龄880~735Ma,后期岩浆热液型铜钼矿成矿年龄为514~502Ma。这些发现对进一步认识总结中非铜矿带上的矿床成因及成矿规律具有重要意义。     

北祁连山寒山金矿床成矿作用同位素地质年代学

位于北祁连山西段安西县的寒山金矿是一个较特殊的、以剪切带容矿的中浅成低温热液蚀变岩型金矿床,它赋存于下奥陶统安山英安质火山碎屑岩中,金矿体受韧脆性剪切带内的强变形带控制。根据矿脉矿物组合及相互穿插关系,原生热液成矿期成矿作用可分为5个矿化阶段。其中,金毒砂石英阶段和金黝铜矿多金属硫化物阶段为主要金成矿阶段。年代学研究表明,金毒砂黄铁矿石英阶段含金石英脉RbSr等时线年龄为372±8Ma,热液蚀变岩RbSr等时线年龄为339±10Ma,矿区辉长闪长岩及南侧青山花岗闪长岩锆石UPb年龄分别为370±25Ma和347.1±6.4Ma,表明区内岩浆侵入活动与成矿作用均发生在晚泥盆世—早石炭世,相当于北祁连山碰撞造山向陆内伸展转变时期,从而揭示了成矿作用是后碰撞造山阶段构造岩浆流体“三位一体”共同作用之产物。     

黑龙江东部那丹哈达地体燕山期金铜成矿系统——中生代岩浆作用与成矿背景

那丹哈达地体位于锡霍特—阿林造山带中部西缘,中生代以来发生了剧烈的构造—岩浆—成矿作用,发育有热泉型、火山热液型、浅成低温热液型以及矽卡岩型等铜金矿床。本文在详细的野外地质调查基础上,对四平山、先锋北山、258高地和跃进山4个典型矿床的成矿岩体进行主量元素、稀土、微量元素地球化学特征分析以及锆石U- Pb年代学研究,旨在探讨研究区燕山期铜金成矿构造背景与成矿模式。研究结果表明,四平山金矿床、先锋北山金矿床、258高地金矿床和跃进山铜金矿床成矿岩体的LA- ICP- MS锆石U- Pb年龄分别为122. 5±1. 1 Ma、117. 0±0. 4 Ma、116. 9±0. 8 Ma和115. 7±1. 1 Ma,矿床成矿时代属于早白垩世晚期。4个矿床的成矿岩体具有相似的岩石地球化学特征,属于中分异I型花岗岩,岩浆来源于地壳物质部分熔融源区,形成于碰撞后构造背景。结合矿床地质背景、锆石U- Pb年代学特征、地球化学特征以及区域构造演化,本文认为四平山金矿床、先锋北山金矿床、258高地金矿床和跃进山铜金矿床的成矿时代基本一致,成因均与燕山期中酸性岩浆相关,属于同一成矿系列,铜金成矿作用与古太平洋板块俯冲作用密切相关。     

安徽冬瓜山层状铜矿床成矿机制及热液叠加改造作用时代研究

在燕山中晚期(约140～135Ma),扬子板块北缘处于碰撞晚期与碰撞后的伸展构造背景,铜陵地区发生了大规模岩浆侵入,导致早期形成的喷流沉积层状矿床或矿胚层发生热液叠加改造作用。作为典型矿例之一,冬瓜山矿床的矿体主要呈层状赋存于泥盆系顶部砂岩至石炭系灰岩之间。与热液叠加改造作用有关的岩浆岩为青山脚石英闪长岩-石英闪长斑岩,全岩Rb-Sr同位素年龄为135.6±1.4Ma。热液交代形成的主矿化期石英脉中流体包裹体具有高温和高盐度特征,Rb-Sr同位素年龄为134±11Ma,氢、氧同位素显示成矿流体主要来源于岩浆。综合同位素年龄和矿床地质及流…     

滇西北普朗斑岩铜矿床成矿时代及其意义

普朗斑岩铜矿在中国斑岩铜矿床中有其特殊性,无论对中甸岛弧带的基础地质还是矿产资源评价预测的研究,都具有重要意义。然而,该斑岩铜矿床无确切的年代学数据。通过作辉钼矿Re-Os年龄和单矿物K-Ar年龄测定,首次确定了普朗斑岩铜矿床内具有钾硅酸盐化的黑云石英二长斑岩成矿作用的活动时间为(235.4±2.4)Ma～(221.5±2.0)Ma,石英-辉钼矿阶段的辉钼矿Re-Os年龄大致为(213±3.8)Ma,两者十分相近。表明普朗斑岩铜矿床的成矿作用是在印支期完成的。主矿体钾长石K-Ar年龄显示热液活动持续到(182.5±1.8)Ma左右,说明与斑岩铜矿有关的热液系统寿命可达40Ma之久。这种长寿命的热液系统是高品位大规模的斑岩铜矿形成的必要条件之一。     

铜陵冬瓜山层状铜矿同位素地球化学及成矿机制研究

长江中下游地区是中国重要的铜、金、硫产地,区内分布着一系列喷流沉积及喷流沉积热液叠加改造型层状铜金矿床。本文以冬瓜山层状铜矿床为例,通过热液流体和矿石同位素地球化学研究,探讨层状铜矿床的成矿机制,重点分析了成矿物质的来源。冬瓜山铜矿床热液流体氢、氧、碳和锶同位素分析表明,成矿热液流体主要来自岩浆,混有少量大气降水;CO2可能主要来自被岩浆同化的原始地层中海相沉积碳酸盐;ISr具有地壳物质来源的特征。各种类型矿石的硫、铅同位素研究显示,硫具有海底喷流沉积和后期岩浆热液叠加作用的特征,铅则以上地壳铅为主,混有少量的地幔铅。上述同位素地球化学特征表明冬瓜山层状铜矿床是在原始沉积基础上,经燕山期岩浆热液叠加成矿作用所形成。     

福建漳平北坑场钼多金属矿床辉钼矿Re-Os同位素年龄

福建漳平钼多金属矿床位于闽西南晚古生代坳陷东缘。中生代以来,闽西南坳陷经历了强烈的构造岩浆作用的改造,并伴随多期次成矿作用的发生。已有同位素年代学研究成果表明该区存在早侏罗世、中侏罗世以及早白垩世成矿作用,但缺少与晚侏罗世大规模岩浆作用相关的成矿年代学记录。本文选取漳平北坑场钼多金属矿床开展辉钼矿的Re-Os同位素年代学研究。根据Re-Os同位素测年结果,结合矿床围岩蚀变及矿化特征以及与岩体的相互关系,指出钼矿化的形成经历了多个成矿阶段,其中小规模的矿化发生在148.8±2.2Ma。主矿化阶段形成的矿床以细脉或网脉状赋存于下二叠统翠屏山组石英细砂岩中,其等时线年龄为139.8±2.3Ma~143.7±2.1Ma,为晚侏罗世~早白垩世成矿。成矿物质主要来源于特提斯向环太平洋构造域转换后闽西南地区晚侏罗世－早白垩世壳源花岗岩浆。     

熊耳山—外方山矿集区中生代Au-Mo成矿系统

熊耳山—外方山矿集区位于秦岭造山带之华北板块南缘,经历了复杂的碰撞造山过程,成矿时间跨度大,成矿强度高,成矿作用多样。复合造山过程和相应的成矿作用已被深入研究,但成矿系统的划分和叠加成矿作用尚需研究。本文将熊耳山—外方山矿集区发育的Au-Mo矿床划分为造山型Mo矿床、斑岩型Mo矿床、岩浆热液脉型Mo矿床、造山型Au矿床和岩浆热液型Au矿床5个类型,对应5种成矿系统：(1)造山型Mo矿床形成于250~227 Ma的同碰撞环境和227~194 Ma的后碰撞环境,为变质热液萃取壳源Mo成矿;(2)斑岩型Mo矿床形成于163~135 Ma的洋陆俯冲环境和135~116 Ma的岩石圈减薄环境,为岩浆热液携带幔源或壳源Mo成矿;(3)岩浆热液脉型Mo矿床形成于227~194 Ma的后碰撞环境,为岩浆热液携带幔源Mo成矿;(4)造山型Au矿床在三叠纪发生了预富集作用,主要形成于163~135 Ma的洋陆俯冲环境和135~103 Ma的岩石圈减薄环境,为变质热液萃取壳源Au成矿;(5)岩浆热液型Au矿床仅形成于135~103 Ma的岩石圈减薄环境,为岩浆热液携带壳源Au成矿。矿集区主要存在两种叠加成矿作用,即不同构造背景下多种成矿系统的叠加和同一构造背景下不同成矿系统的叠加。     

湖南雪峰山地区铲子坪和大坪金矿成矿作用年代学研究

湘西铲子坪和大坪等大型金矿是雪峰山地区颇具代表性的金矿床。本次研究获得该两矿床含金石英脉RbSr等时线年龄分别为205.6±9.4Ma和204.8±6.3Ma,矿区外围黄茅园黑云母花岗岩体锆石SHRIMP UPb年龄为222.3±1.7Ma,测定结果表明成岩和成矿作用均发生于印支期,成矿作用可能与区域性逆冲推覆作用及相伴生的酸性岩浆侵位密切相关;矿床成因类型应为岩浆热液型,而不宜归为韧性剪切带型或构造蚀变岩型。     

西藏铁格隆南超大型铜(金、银)矿床地质、蚀变与矿化

铁格隆南是班公湖-怒江成矿带西段重要的斑岩-浅成低温热液铜(金、银)矿床,也是西藏地区首个铜资源量超过1000万吨的超大型铜(金、银)矿床,其蚀变与矿化结构的精细解剖,对完善区域成矿理论和指导找矿实践有重要的指导意义。文章基于详细的野外地质调查、钻孔编录和镜下鉴定,识别出铁格隆南矿床具有斑岩和浅成低温热液叠加成矿作用特征。其中,斑岩成矿作用主要位于矿床深部及外围,以细脉状、脉状、浸染状黄铁矿、黄铜矿、斑铜矿及少量辉钼矿等为主,蚀变为钾硅化、青磐岩化、黄铁绢英岩化,发育A、B、D型脉体。浅成低温热液成矿作用主要产于矿床中-浅部,叠加于斑岩成矿作用之上,以浸染状-脉状黄铁矿、硫砷铜矿、斑铜矿、铜蓝、蓝辉铜矿、斯硫铜矿、雅硫铜矿、久辉铜矿等Cu-S体系矿物为特征,蚀变为高级泥化,广泛发育N脉(即高岭石或明矾石-硫化物脉)。蚀变、矿化特征及脉体穿切关系揭示,矿床成岩成矿作用可细分为岩浆期(Ⅰ)、岩浆-热液期(Ⅱ)和表生期(Ⅲ)。成岩成矿年代学结果揭示,矿区内闪长玢岩侵位时代较早(123 Ma),代表岩浆活动上限;花岗闪长斑岩(122～120 Ma)是主要的含矿斑岩,与成矿作用关系最为密切;火山岩覆盖于地表,喷发时代较晚(111 Ma),代表成矿后岩浆活动的产物。钾硅化的黑云母和黄铁绢英岩化的绢云母40Ar-39Ar年龄分别(121.1±0.5) Ma、(120.8±0.9)Ma与斑岩成矿作用的辉钼矿Re-Os年龄((121.2±1.2) Ma)一致,而高级泥化的明矾石40Ar-39Ar年龄为(117.9±1.6)Ma与浅成低温热液矿化的黄铁矿Rb-Sr年龄((117.5±1.8)Ma)一致。所以,依据时空关系,铁格隆南超大型矿床成矿作用可细分为岩浆热液成矿作用(123～119 Ma)、浅成低温热液成矿作用(118～117 Ma)和火山岩覆盖保存(111～110 Ma)3个阶段。     

U–Pb and Re–Os Geochronology of the Tongcun Molybdenum Deposit and Zhilingtou Gold‐Silver Deposit in Zhejiang Province,Southeast China,and Its Geological Implications

Mesozoic ore deposits in Zhejiang Province, Southeast China, are divided into the northwestern and southeastern Zhejiang metallogenic belts along the Jiangshan–Shaoxing Fault. The metal ore deposits found in these belts are epithermal Au–Ag deposits, hydrothermal‐vein Ag–Pb–Zn deposits, porphyry–skarn Mo (Fe) deposits, and vein‐type Mo deposits. There is a close spatial–temporal relationship between the Mesozoic ore deposits and Mesozoic volcanic–intrusive complexes. Zircon U–Pb dating of the ore‐related intrusive rocks and molybdenite Re–Os dating from two typical deposits (Tongcun Mo deposit and Zhilingtou Au–Ag deposit) in the two metallogenic belts show the early and late Yanshanian ages for mineralization. SIMS U–Pb data of zircons from the Tongcun Mo deposit and Zhilingtou Au–Ag deposit indicate that the host granitoids crystallized at 169.7 ± 9.7 Ma (2σ) and 113.6 ± 1 Ma (2σ), respectively. Re–Os analysis of six molybdenite samples from the Tongcun Mo deposit yields an isochron age of 163.9 ± 1.9 Ma (2σ). Re–Os analyses of five molybdenite samples from the porphyry Mo orebodies of the Zhilingtou Au‐Ag deposit yield an isochron age of 110.1 ± 1.8 Ma (2σ). Our results suggest that the metal mineralization in the Zhejiang Province, southeast China formed during at least two stages, i.e., Middle Jurassic and Early Cretaceous, coeval with the granitic magmatism.     

U–Pb and Re–Os Geochronology of Karamay Porphyry Mo–Cu Deposit in Western Junggar,NW China

The Karamay porphyry Mo–Cu deposit, discovered in 2010, is located in the West Junggar region of Xinjiang of northwest China. The deposit is hosted within the Karamay granodiorite porphyry that intruded into Early Carboniferous sedimentary strata and its exo‐contact zone. The LA‐ICPMS U–Pb method was used to date the zircons from the granodiorite samples of the porphyry. Analyses of 12 spots of zircons from the granodiorite samples yield a U–Pb weighted mean age of 300.8 ± 2.1 Ma (2σ). Re–Os dating for five molybdenite samples obtained from two prospecting trenches and three outcrops in the deposit yield a Re–Os isochron age of 294.6 ± 4.6 Ma (2σ), with an initial ¹⁸⁷Os/¹⁸⁸Os of 0.0 ± 1.1. The isochron age is within the error of the Re–Os model ages, demonstrating that the age result is reliable. The Re–Os isochron age of the molybdenite is consistent with the U–Pb age of the granodiorite porphyry, which indicates that the deposit is genetically related with an Early Permian porphyry system. The ages of the Karamay Mo–Cu deposit and the ore‐bearing porphyry are similar to the ages of intermediate‐acid intrusions and Cu–Mo–Au polymetallic deposits in the West Junggar region. This consistency suggests the same geodynamic process to the magmatism and related mineralization.     

Re–Os and U–Pb Geochronology of Porphyry and Skarn Types Copper Deposits in Jilin Province,NE China

Jilin Province in NE China lies on the eastern edge of the Xing–Meng Orogenic Belt. Mineral exploration in this area has resulted in the discovery of numerous large, medium, and small sized Cu, Mo, Au, and Co deposits. To better understand the formation and distribution of both the porphyry and skarn types Cu deposits of the region, we examined the geological characteristics of the deposits and applied zircon U–Pb and molybdenite Re–Os isotope dating to constrain the age of the mineralization. The Binghugou Cu deposit yields a zircon U–Pb age for quartz diorite of 128.1 ± 1.6 Ma; the Chang'anpu Cu deposit yields a zircon U–Pb age for granite porphyry of 117.0 ± 1.4 Ma; the Ermi Cu deposit yields a zircon U–Pb age for granite porphyry of 96.8 ± 1.1 Ma; the Tongshan Cu deposit yields molybdenite Re–Os model ages of 128.7 to 130.2 Ma, an isochron age of 129.0 ± 1.6 Ma, and a weighted mean model age of 129.2 ± 0.7 Ma; and the Tianhexing Cu deposit yields molybdenite Re–Os model ages of 113.9 to 115.2 Ma, an isochron age of 114.7 ± 1.2 Ma, and a weighted mean model age of 114.7 ± 0.7 Ma. The new ages, combined with existing geochronology data, show that intense porphyry and skarn types Cu mineralization was coeval with Cretaceous magmatism. The geotectonic processes responsible for the genesis of the Cu mineralization were probably related to lithospheric thinning. By analyzing the accumulated molybdenite Re–Os, zircon U–Pb, and Ar–Ar ages for NE China, it is concluded that the Cu deposits formed during multiple events coinciding with periods of magmatic activity. We have identified five phases of mineralization: early Paleozoic (~476 Ma), late Paleozoic (286.5–273.6 Ma), early Mesozoic (~228.7 Ma), Jurassic (194.8–137.1 Ma), and Cretaceous (131.2–96.8 Ma). Although Cu deposits formed during each phase, most of the Cu mineralization occurred during the Cretaceous.     

江西新余良山钼矿锆石U-Pb和辉钼矿Re-Os年龄

良山钼矿是钦杭成矿带近年发现的大中型矿床,在矿化特征分析的基础上,对其进行了成岩成矿年代学研究。采用LAICP-MS锆石U-Pb测年技术,得到矿区内石英闪长斑岩的成岩年龄为168.2±2.3Ma。通过矿床辉钼矿Re-Os同位素分析,获得其等时线年龄为168.9±1.4Ma。指示成岩作用与成矿作用同时发生,含矿热液活动与岩浆活动有密切的关系,岩浆活动可能是形成良山钼矿床的重要因素。良山钼矿床的成矿时间与钦杭成矿带内华南燕山期第一阶段大规模多金属矿化时间(170Ma)吻合。良山钼矿床形成于同一区域成矿背景下,是区域构造岩浆作用的产物,为华南燕山期成矿作用的组成部分。     

内蒙古黄岗夕卡岩型锡铁矿床辉钼矿Re-Os年龄及其地质意义

内蒙古黄岗大型夕卡岩型锡铁矿床位于大兴安岭南段黄岗梁-乌兰浩特锡铅锌铜多金属成矿带。本文利用辉钼矿Re-Os同位素定年方法对黄岗夕卡岩型矿体中5件辉钼矿样品进行了成矿年代测定,获得辉钼矿Re-Os模式年龄为134.6±2.0～136.5±1.9Ma,加权平均年龄为135.31±0.85Ma。辉钼矿Re含量高,显示有地幔物质体参与了成矿过程。大兴安岭地区成矿作用以中生代燕山期成矿为主,存在140～130Ma左右、180～160Ma左右的两次成矿爆发期,其中140～130Ma左右主要出现在岩石圈伸展减薄背景下,与燕山晚期侵入的小岩体有关的锡铅锌铜银多金属矿床;180～160Ma左右主要出现与燕山早期西伯利亚与华北板块后碰撞造山有关的钼铅锌铜金多金属矿床。黄岗锡铁矿床是在古太平洋板块俯冲大陆边缘弧后伸展环境下,发生的大规模成矿作用的产物。     

安徽铜陵凤凰山夕卡岩型铜矿床中辉钼矿Re-Os同位素年龄及其地质意义

铜陵矿集区是我国长江中下游Cu-Au-Fe-Mo成矿带中最重要的有色金属基地之一,凤凰山矿床是铜陵矿集区的重要组成部分,为一个典型的夕卡岩型铜矿床。本文利用Re-Os同位素定年方法对凤凰山铜矿床进行了成矿时代测定,获得了辉钼矿的Re-Os同位素模式年龄范围为139.1±2.4～142.0±2.2Ma,等时线年龄为141.1±1.4Ma,与矿区内石英二长闪长岩和花岗闪长岩SHRIMP锆石U-Pb年龄(144.2±2.3Ma)相吻合,也与铜陵地区其他矿田的成矿时代基本一致,可能为岩石圈减薄事件的成矿响应。     

Zircon U–Pb and molybdenite Re–Os geochronology of copper–molybdenum deposits in southeast Liaoning Province,China

ABSTRACT

Liaoning Province in China is an area known for the occurrence of numerous copper and/or molybdenum deposits of variable size. However, the age of mineralization and tectonic setting in this region are still a subject of debate. In this study we describe the geology of these deposits and apply zircon U–Pb and molybdenite Re–Os isotopic dating to constrain their ages and define the metallogenic epochs of this province. The Huatong Cu–Mo deposit yields molybdenite Re–Os model ages of 127.6–126.3 Ma and an isochron age of 127.4 ± 0.7 Ma. The Dongbeigou Mo deposit yields molybdenite Re–Os model ages of 132.6–127.1 Ma, an isochron age of 128.1 ± 5.1 Ma, and a zircon U–Pb age of 129.4 ± 0.3 Ma for the associated monzogranite. The granodiorite associated with the Wanbaoyuan Cu–Mo deposit yields a zircon U–Pb age of 128.4 ± 1.1 Ma; the plagiogranite associated with the Yaojiagou Mo deposit yields an age of 167.5 ± 0.9 Ma; and the biotite–plagioclase gneiss from the Shujigou Cu deposit yields an age of 2549.4 ± 5.6 Ma. These results, together with previous geochronology data, show that intense Cu–Mo porphyry and skarn mineralization were coeval with Early–Middle Jurassic and Early Cretaceous granitic magmatism. The former was associated with the orogeny that followed the collision of the Siberian and North China plates and the resulting closure of the palaeo-Asian Ocean, and the latter with rifting that followed the subduction of the palaeo-Pacific Plate and associated lithospheric thinning. Volcanogenic massive sulfide Cu deposit. mineralization took place much earlier, in the late Archaean, and was related to continent–continent collision, palaeo-ocean closure, the formation of a united continental landmass, bimodal volcanism, magma emplacement, and subsequent metamorphism and deformation of syn-collisional granites.     

U–Pb and Re–Os Ages of the Huaheitan Molybdenum Deposit,NW China

The Huaheitan molybdenum deposit in the Beishan area of northwest China consists of quartz‐sulfide veins. Orebodies occur in the contact zone of the Huaniushan granite. LA‐ICPMS U–Pb zircon dating constrains the crystallization of the granite at 225.6 ± 2.2 Ma (2σ, MSWD = 4.5). Re–Os dating of five molybdenite samples yield model ages ranging from 223.2 ± 3.5 Ma to 228.6 ± 3.4 Ma, with an average of 225.2 ± 2.4 Ma. The U–Pb and Re–Os ages are identical within the error, suggesting that the granite and related Huaheitan molybdenum deposit formed in the Late Triassic. Our new data, combined with published geochronological results from the other molybdenum deposits in this region, imply that intensive magmatism and Mo mineralization occurred during 240 Ma to 220 Ma throughout the Beishan area.     

江西省武功山地区浒坑钨矿床的Re-Os年龄及其地质意义

浒坑钨矿床是位于江西省中部武功山成矿带的大型石英脉型黑钨矿床。为了确定该矿床的成矿时代,笔者选取了浒坑含钨石英脉中与黑钨矿共生的辉钼矿进行了高精度Re-Os同位素定年,并获得5个辉钼矿样品的Re-Os等时线年龄和模式加权平均年龄分别为150.2±2.2Ma和149.82±0.92Ma。测年数据表明浒坑钨矿床的成矿时代为150Ma左右,是华南地区中生代大规模成岩成矿作用高峰期的产物。辉钼矿含铼较低,表明成矿物质可能来自壳源,与形成浒坑花岗岩体的燕山期重熔S型花岗岩岩浆活动有关。该矿床形成于燕山期岩石圈伸展减薄环境。     

Geology,Geochemistry, and Geochronology of the Fenghuangshan Skarn‐type Copper Deposit in the Tongling Ore Cluster,Anhui Province,East China

The Fenghuangshan skarn-type Cu deposit, Tongling Ore Cluster, Anhui Province, is an important component in the Middle–Lower Yangtze River ore-forming belt. To better understand magmatism and its relationship to mineralization, we investigated geochemical features, ore-forming fluids, and geochronology of the Xinwuli intrusion and the related Fenghuangshan Cu deposit. Lithogeochemical characteristics show that the Xinwuli quartz monzodiorite is formed by mixing magma derived from upper mantle alkaline basalt that has been contaminated by crust materials. C, H and O isotopes indicate that ore-forming fluids mainly come from the magma, with minor amounts of meteoric fluids involved at the late stage. S and Pb isotopic components indicate that ore-forming materials are derived from the mantle. Molybdenite Re–Os isotopic dating yields Re–Os model ages ranging from 139.1±2.4 Ma to 142.0±2.2 Ma, with an isochronal age of 141.1±1.4 Ma, which is consistent with sensitive, high-resolution ion microprobe (SHRIMP) zircon U–Pb ages of quartz monzodiorite and granodiorite in the mining area. Dating analysis yields ages from 136.0±2.0 Ma to 143.0±2.4 Ma for the quartz monzodiorite (a weighted average of 139.4±1.2 Ma) and ages from 136.7±2.0 Ma to 145.3±2.4 Ma for granodiorite (a weighted average of 141.0±1.1 Ma).