陕西凤县八卦庙金矿脆韧性剪切带控矿特征及成矿模式探讨  

Ore-controlling Characteristics and Metallogenic Model of Brittle Ductile Shear Zones of Baguamiao Gold Deposit in Fengxian County,Shaanxi

作　　者：李永勤 王瑞廷 丁坤[2] 孟德明[2] 谭雯[1] 

机构地区：[1]西北有色地质勘查局,陕西西安710054 [2]长安大学地球科学与资源学院,陕西西安710054

出　　处：《西北地质》2015年第1期101-108,共8页Northwestern Geology

基　　金：国土资源部公益性行业科研专项经费课题(201111007-3);"十二五"国家科技支撑计划项目课题(2011BAB04B05)

摘　　要：陕西凤县八卦庙金矿床是西秦岭已探明的超大型金矿床,矿床位于苏家沟-空棺沟复式向斜北翼之八卦庙次级倒转向斜北翼,主要赋矿岩性为星红铺组下段铁白云石粉砂质千枚夹条带状大理岩化灰岩。金矿体受北西向F13大断裂下盘的韧性剪带控制,形成石英脉型、构造蚀变岩型和蚀变糜棱岩型3种金矿化类型,而以构造蚀变岩型金矿化为主。韧性剪带剪切带从地表浅部向深部依次分为脆性区、脆-韧过渡区和韧性区,分别与石英脉型、构造蚀变岩型和蚀变糜棱岩型金矿化相对应。印支期,随着造山运动、地壳隆升,剪切带中深层次的韧性剪切变形的糜棱岩被抬升,依次与其上的脆-韧性及脆性剪切叠加,从而构成不同类型的金矿化叠加富集,形成金的贫矿体。印支—燕山期,随着岩浆作用活跃并开始沿北东向F22断裂上侵,驱使深部及两侧围岩中金离子活化,分别向F22断裂西侧的F21和东侧F23断裂迁移、聚集,对韧性剪切带形成的贫矿体叠加改造富集,最终就位构成金矿体。Located on the north wing of the Baguamiao secondary inverted syncline of north Sujia- gou-Kongguangou composite syncline, the Baguamiao super-large gold deposit is the unique of the west Qinling area. The major hosted rocks are dolomitic silty phyllite and stripped marbleized limestone of the lower Xinghongpu formation. Gold orebodies are controlled by ductile shear zones under the northwest-trending F13 great fault and develops into three types of gold minerali- zation which are quartz vein type, structural altered type and altered mylonite type, with struc- tural altered type dominating the mineralization. From surface to deep, ductile shear zones are fragile to fragile-ductile to ductile in order, which are corresponding with the three types of gold mineralization. Due to the orogenesis and crust uplift in Indosinian, ductile shear deformed mylo- nite of the ductile zone is uplifted, superimposed to the fragile-ductile and ductile shearing zones, thus constituting different types of gold mineralization superposition enrichment, then forming deficient gold orebodies. During Indosinian-Yanshanian, magmatism became active and intruded along the northeast-trending F22 fault, which drives the gold ions of deep and both sides of the surrounding rocks activate, migrate to west of F22 and east F23 fault and enrich. By superposi- tion, transformation and enrichment on the former deficient gold bodies, the gold orebodies took the place and are finally formed.

关 键 词：八卦庙金矿床 韧性剪切带 成矿流体 同构造石英脉 成矿模式 

分 类 号：P618.51[天文地球—矿床学]