摘要
蚀变糜棱岩型金矿是一种成矿机制与控矿因素都与韧性剪切带及其糜棱岩密切相关的金矿床类型。研究表明 :1深部韧性剪切变形是元素分异迁出区 ,未叠加蚀变矿化的糜棱岩变形越强 ,Au丰度就越低 ;2中浅层次变形域是 Au元素聚集区 ,矿化发生于韧性剪切带糜棱岩抬升至较浅部位叠加了韧脆性变形阶段。构造变形越强的糜棱岩 ,越易叠加矿化 ,Au元素丰度越高 ;3强变形或者大构造差应力不仅是促使 Au元素活化分异、形成含 Au热液、使 Au元素进入到成矿过程 ,而且驱使含矿热液运移 ,更是为金矿成矿创造理想容矿 (赋矿 )空间的构造动力学条件 ;4蚀变糜棱岩型金矿床的特点是 :成矿较韧性变形滞后、成矿深度较韧性变形浅、矿化仅发育于较小规模的韧性剪切带中、 Au元素来源于围岩和深部、变形强度与 Au元素丰度具有特殊关系。
The altered mylonite type gold deposit is a kind of gold deposits whose ore\|forming mechanism and ore\|controlling factors are closely related to the ductile shear zone and mylonite zones.Based on the sutdy of relationship between gold abundance and structural deformation,the author has reached the following conclusions:(1)Deep ductile shear deformation remobilizes Au,forming ore\|bearing tectono\|metamorphic hydrothermal solutions which migrate out from the domain.In non\|mineralized mylonite,the stronger the ductile shear deformation,the lower the gold abundance.The gold abundance of ultramylonite is clearly lower than that of coarse mylonite.(2)The medium\|shallow deformation domain is a favorable site for gold accumulation.The altered mylonite type gold deposit is formed where the mylonite of ductile shear zone is uplifited and the mylonite is altered and mineralized by the ore\|bea\| ring hydrothermal solutions.So in mineralized mylonite the stronger the ductile shear defomration,the higher the gold abundance.There is a positive correlation between gold abundance and structural differential stress.Moreover,the gold content is also related to the type of mylonite,the character of fabric,the mechanism of deformation and the size of strain.All these features show that gold enrichment and mineralization are controlled by factors in the aspects of macrostructure and microstructure.(3)Stronger deformation and higher structural differential stress are not direct dynamic conditions for gold mineralization.Nevertheless,they are among the factors which not only promote remobilization and differentiation of gold to form ore\|bearing hydrothermal solutions and cause Au to enter the mineralization process,but also drive the ore\|bearing hydrothermal solutions to migrate,thus producing the suitalbe ore\|hosting sites.(4)Altered mylonite type gold deposits have unique character.Gold mineralization occurs later and shallower than ductile shear deformation.Ore elements are derived mainly from surrounding or deep\|seated rocks.Gold orebodies mainly occur in some smaller ductile shear zones.The relationship between gold abundance and deformation intensity in mineralized mylonite is opposite to that in nonmineralized one.
出处
《矿床地质》
CAS
CSCD
北大核心
2000年第1期17-25,共9页
Mineral Deposits
基金
地科定 ( 96-2 )项目资
关键词
构造变形
糜棱岩型金矿
金矿床
金元素丰度
structural deformation,abundance of Au,relationship,gold deposit,altered mylonite type
