老挝帕奔金矿地质-构造地球化学特征及成矿机理  

Characteristics of geology and structural geochemistry and metallogenic mechanism of Phapon gold deposit in Laos

作　　者：杨昌正[1] 沈利霞[1] 周琳[1] 冯建忠[1] 刘学武[1] 

机构地区：[1]天津华北地质勘查局,天津300170

出　　处：《矿产与地质》2017年第1期11-22,共12页Mineral Resources and Geology

基　　金：老挝琅勃拉邦省爬奔金矿床成矿规律及找矿方向研究项目(编号:HK2015-B1)资助

摘　　要：老挝帕奔金矿是一种独特的矿床类型,矿体产在下二叠统灰岩中,构造控矿明显,矿体受韧-脆性剪切带和断裂控制。有蚀变岩型、方解石脉型和角砾岩型三种矿化类型。蚀变类型单一,为碳酸盐化。矿石中没有硫化物,脉石矿物几乎只有方解石。岩石变形特征研究表明,从造山早期开始一直到造山后存在一系列韧性-脆韧性-韧脆性-脆性递进变形,在剪切递进变形过程中普遍存在压溶现象。不同期次剪切变形构造岩地质地球化学及含矿性研究表明,金富集成矿主要发生在造山晚期递进变形中韧性-脆性转换期与造山后压扭性-张性力学转换期,剪切压溶是帕奔金矿主要控矿因素。大地构造演化与成矿地质特征表明,帕奔金矿成矿与华力西晚期造山过程递进变形有一系列的联系,三种类型的金矿化与韧性、脆韧性剪切、断裂活动构造发展有关。根据剪切和压溶的发育特点和不同时期方解石脉体及矿化类型,将成矿机理概括为:剪切压溶活化,剪切扩容与交代,构造扩张与液压致裂。Phapon gold deposit in Laos is one special deposit type, in which ore bodies are hosted in Lower Permian limestone and controlled by ductile-brittle shearing and faulting structures. There are three mineralization types, altered rock type, calcite vein type and breccia type. The alteration type is simple and just carbonization. There is no sulfide in ore and calcite is the only gangue mineral. Deformation feature of altered rocks indicates that there are a series of ductile, brittle-ductile, ductile-brittle and brittle progressive shear deformation from the beginning to the end of the whole orogenic process. Researches of geology and geochemistry and mineraliztion feature of tectonite in different stages of shear deformation show that gold enrichment and mineralization mainly took place during transition period from ductile shearing to brittle shearing in the late period of orogenic process and transition period from compression to extension of progressive deformation after orogenic process. The shear and pressure solution is the main ore-controlling factor in Phapon gold deposit. The tectonic evolvement and geological mineralization feature indicates that the mineralization of Phapon gold deposit is closely related to progressive deformation in the orogenic process in the late Variscan period. Three types of mineralization are related to ductile shearing, ductile-brittle shearing and faulting structures. As a result, the metallogenic mechanism is summarized as gold activation from shear pressure solution, shear extension and metasomatism, structural expanding and hydraulic pressure fracturing.

关 键 词：帕奔金矿 构造地球化学 脆-韧性剪切 递进变形 压溶 老挝 

分 类 号：P618.51[天文地球—矿床学]