内蒙古沙章土锡铜多金属矿床成矿年代学及成因探讨  

Discussion of metallogenic age and ore genesis for Shazhangtu Sn-Cu polymetallic deposit in Inner Mongolia

作　　者：吕云鹤 董国臣[1] 吕书俊 李洪宾 LU YunHe;DONG GuoChen;LÜShuJun;LI HongBin(School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China;Shandong Geological Planning and Investigation Institute of Coal Field,Jinan 250104,Shandong,China)

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]山东省煤田地质规划勘察研究院,山东济南250104

出　　处：《矿床地质》2023年第2期396-410,共15页Mineral Deposits

基　　金：自然科学基金重大研究计划(编号:92062217)资助。

摘　　要：沙章土锡铜多金属矿位于内蒙古中部,近年来区内锡矿找矿工作的新发现,锡矿体为呈脉状、浸染状分布的电气石脉、电英岩及电英岩化蚀变岩,含锡矿物主要为锡石;铜矿体为浸染状分布的黄铜矿化电英岩化蚀变岩、方铅矿-闪锌矿-黄铜矿化蚀变岩,含铜矿物主要为黄铜矿,同时,经由钻探工程在矿床深部发现有闪长玢岩岩体。为了查清锡铜矿体成矿年龄及成矿物质来源,明确矿床成因类型,进一步指导找矿工作,文章在野外调查和室内综合研究基础上,对锡石开展了LA-MC-ICP-MS U-Pb定年及电子探针分析工作,并对共生的硫化物进行了硫同位素测试。测试结果显示,锡石成矿年龄为(316.3±8.9)Ma,为海西期晚石炭世阶段的产物;探针数据显示其成因为热液型锡石;硫同位素测试结果,δ^(34)S值为0.43‰~7.34‰,平均值4.39‰,具混合硫源特征。综上所述,笔者初步认为沙章土锡铜矿床的成因类型是与闪长玢岩有关的岩浆热液型。The Shazhangtu tin-copper polymetallic deposit is located in the central part of Inner Mongolia.It is a new discovery during the tin ore prospecting in the region in recent years.The tin ore bodies are tourmaline veins,tourmalite and tourmaline-quartz altered rocks with cassiterite as the main ore mineral in veins or dissemination.The copper ore bodies are tourmaline-quartz altered rocks and galena-sphalerite-chalcopyrite altered rocks with chalcopyrite as the main copper bearing mineral.Concealed diorite porphyrite was found in the deep part of the deposit by drilling.In order to strengthen the study on the ore-forming age and the source of ore-forming materials of the tin-copper ore body,clarify the genetic type of the deposit,and further guide the prospecting work,based on detailed field investigation and indoor identification,La-MC-ICP-MS U-Pb dating and electron probe composition analysis of cassiterite were carried out,and also the sulfur isotope analyses of associated sulfide minerals.The result shows that the ^(206)Pb/^(207)Pb-^(238)U/^(207)Pb isochron age of cassiterite is(316.3±8.9)Ma,which is the product of the Late Carboniferous stage of Hercynian,electron probe analytical data of cassiterite illustrate that the cassiterite is from a hydrothermal deposit.The sulfur isotope results show that theδ34S value of sulfide ranges from 0.43‰ to 7.34‰,with an average value of 4.39‰,indicating that the sulfide has the characteristics of mixed sulfur source.In conclusion,it is preliminarily considered that the Shazhangtu tin-copper deposit is a magmatic hydrothermal type related to dioritic porphyrite magmatic intrusion.

关 键 词：地质学 锡石 成矿年龄 硫同位素 成矿物质来源 矿床成因 

分 类 号：P618.41[天文地球—矿床学] P618.44[天文地球—地质学]