江西金山金矿控矿韧性剪切带的递进变形成矿机理：显微构造证据  

Gold Mineralization during Progressive Deformation in Jinshan Ductile Shear Zone,Jinshan Gold Deposit,Jiangxi Province:Evidence from Microscopic Deformation Structures

作　　者：王春增 李晓峰[2] 易先奎 

机构地区：[1]美丽缅因州大学Presque Isle分校,Maine 04769,USA [2]中国地质科学院矿产资源研究所,北京100037 [3]江西有色地质矿产勘查开发院,南昌330001

出　　处：《桂林工学院学报》2009年第2期169-182,共14页Journal of Guilin University of Technology

基　　金：中国国家自然科学基金资助项目(40403006,40872065);留学人员短期回国讲学专项(40610404013)

摘　　要：在对江西金山金矿控矿韧性剪切带内岩石和矿石的显微构造分析基础上,对剪切带的递进变形与成矿机理进行探讨。研究发现,金山韧性剪切带在韧性—韧脆性递进剪切变形过程中发育3类石英脉透镜体或石香肠构造;剪切压溶和缝合线构造在金山韧性剪切带内强烈发育;扩散蠕变机制是金山韧性剪切带重要的变形机制。大量缝合线构造的形成增强了岩石的孔隙度和渗透率,有利于流体的迁移和沉淀。金山剪切带内变形和成矿作用经历了漫长复杂的地质过程,粗略估算至少跨过了72 Ma。在递进剪切变形过程中经历多种构造变形机制,如经历了以透入性片理为代表的韧性剪切变形机制到以"次级剪切面"构造网络为代表的韧-脆性剪切变形机制的转换。剪切带的递进剪切变形自始至终控制着金的成矿作用过程,没有递进剪切变形也就没有金山金矿的形成。Microscopic deformation structures observed in deformed rocks and ores from Jinshan auriferous ductile shear zone of Jinshan gold deposit, Jiangxi Province, are examined and analyzed. Gold mineralization process during progressive shear deformation in the ductile shear zone is discussed. Three classes of quartz-vein boudinage are found developed within the ductile shear zone with respect to vein and boudinage characteristics and timing of major-phase mineralization. The discovery covers intensive pressure solution and pressure dissolution structures of stylolites or dissolution seams developed in the ductile shear zone in detail. The extensively and intensively developed stylolites help enhance porosity and permeability of the shear zone rocks, and provide pathways for migration of fluids as well as space for silica precipitation. Their presence indicates that fluids-enhanced diffusion creep or diffusional mass transfer is not only an important deformation mechanism but also a critical component of mineralization mechanism for Jinshan auriferous ductile shear zone. The paper estimates a minimum 72 million years span for the progressive deformation and mineralization process associated with multiple deformation mechanisms, and underwent a significant deformation regime transfer from penetrative schistosity-dominated fabric of ductile deformation to a non-penetrative （ at outcrop and microscopic scales） network of ＂second-order＂ shear structures of ductile-brittle deformation. It is concluded that the mineralization process was caused by the progressive shear, and that there would be no such a large gold deposit without the prolonged progressive deformation.

关 键 词：剪切带 递进变形 成矿机理 显微构造 压溶作用 缝合线 金山金矿 

分 类 号：P542.3[天文地球—构造地质学] P618.510.2[天文地球—地质学]