内蒙古白云鄂博群地层岩石地球化学:对浩尧尔忽洞金矿床层控机理研究  

Petrology,Geochemistry and Pb Isotope Composition of Bayan Obo Group in Inner Mongolia:Constraints on the Genesis of Stratabound Haoyaoerhudong Gold Deposit

作　　者：孙亮[1,2] 张林 张海东 Sun Liang;Zhang Lin;Zhang Haidong(School of Earth and Space Sciences;Key Laboratory of Orogenic Belts and Crustal Evolution of Ministry of Education, Peking University, Beijing 100871, China;Tianyu Research Institute of Geology, Shaanxi Coalbed Methane Development Co. Ltd. , Xi＇an 710065;School of Earth Science and Resources, Chang＇an University, Xi＇an 710054, China)

机构地区：[1]北京大学地球科学与空间科学学院,北京100871 [2]北京大学造山带与地壳演化教育部重点实验室,北京100871 [3]陕西省煤层气开发利用有限公司天宇地质研究所,西安710065 [4]长安大学地球科学与资源学院,西安710054

出　　处：《地质科技情报》2018年第1期7-15,共9页Geological Science and Technology Information

基　　金：国家自然科学基金项目(41402042);中国地质调查局项目(12120114021001)

摘　　要：华北克拉通北缘黑色页岩中分布了一系列大型-超大型金矿床和金矿点,但对于沉积地层与层控型金矿床间的成因联系至今尚未完全查明。对白云鄂博群的地层岩石学、地球化学、Pb同位素组成等方面展开了相关研究,以此来讨论地层对于浩尧尔忽洞金矿床的控矿机制。比鲁特组第一、二岩性段是金矿床的主要赋矿围岩,岩性间存在明显的物性差异,并富含碳。金矿石、比鲁特组和海西期岩浆岩的微量元素、稀土元素具有相似的变化曲线,均表现为La、Sm、Y、LREE富集,Nd、Ta、Sr、Zr、Hf、HREE亏损,和明显负Eu异常的特征。比鲁特组炭质板岩中的星点状黄铁矿与金矿石中的硫化物具有相似的Pb同位素组成(208 Pb/204Pb=38.960 0~38.982 9,207Pb/204Pb=15.643 5~15.684 2,206Pb/204Pb=18.566 0~18.921 7)。这些地质与地球化学数据结果表明,形成浩尧尔忽洞金矿床的成矿物质主要来源于白云鄂博群,加里东期区域挤压变形、海西期大规模岩浆活动和海西-印支期脆-韧性剪切作用一方面使地层中的金发生大规模活化、迁移,另一方面为含矿热液提供了良好通道和沉淀空间。比鲁特组中富含的有机质是金沉淀的有利还原剂。There are many large and super-large gold deposits and spots in the Northern China Craton（NCC）,which are hosted by black shales.However,there is currently no model for the role of marine sedimentary rocks in contact with gold deposits.In this paper,we present the results of the petrology,geochemistry and Pb isotope composition of Bayan Obo Group,and discuss the mechanism of Haoyaoerhudong gold ore bodies controlled by strata.There are many abrupt lithologic changes and carbon in the first and second lithologic sections of Bilute Formation,the main host rocks for gold orebodies in the study area.The ore,Bilute Formation and Hercynian magma rocks generally have a similar trace and REE elements variation trend such as the enrichment of La,Sm,Y,and LREE,and the depletion of Nd,Ta,Sr,Zr,Hf,and HREE.The star-like pyrite in carbonaceous slate of Bilute Formation and sulfide in ore have a similar Pb isotope composition,with the ranges of 208 Pb/204 Pb,207 Pb/204 Pb,and 206 Pb/204 Pb varying from 38.960 0 to 38.982 9,15.643 5 to 15.684 2 and 18.566 0 to 18.921 7,respectively.These geological-geochemical characteristics indicate that ore-forming materials mainly come from the strata.On the one hand,the Caledonian regional compression deformation,large scale Hercynian magma intrusion and Hercynian-Indochina brittle-ductile shearing cooperated to make Au to active and migrate,and on the other hand,this cooperation provided better space for fluxion and emplacement of ore-forming fluids.And the carbon in Bilute Formation is better reductant for precipitation of Au in Haoyaoerhudong gold deposit.

关 键 词：浩尧尔忽洞金矿床 白云鄂博群 比鲁特组 星点状黄铁矿 PB同位素 

分 类 号：P59[天文地球—地球化学]