勉—略混杂岩带构造地质特征与金矿成矿——以陕西省略阳县干河坝金矿床为例

GEOLOGICAL CHARACTERISTICS OF MIAN-LUE TECTONIC MELANGE BELT AND GOLD MINERALIZATION IN SHANXI PROVINCE——TAKING GANHEBA GOLD DEPOSIT AS AN EXAMPLE

勉略带经历俯冲叠置、碰撞造山和陆内造山3个阶段构造演化过程。即俯冲期深层次褶皱与右行顺层(片)剪切变形、碰撞期中—深层次褶皱递进变形和高角度逆冲剪切变形、后主造山期陆内造山期中—浅层次左行走滑变形和低角度逆冲推覆构造4期不同构造变形。其中前两期构造阶段对金矿成矿产生重要影响。通过对陕西省略阳县干河坝金矿研究认为:俯冲期剪切变形作用形成金的初始富集;碰撞期逆冲剪切构造为重要的成矿、控矿构造;由于长期的斜向逆冲剪切,形成一系列侧伏方向同剪切运动方向一致的富矿柱。

Mian-Lue belt experienced such three periods of tectonic evolution as subduction overriding,collision orogenesis and intracontinental orogenesis.These movements caused four times different tectonic deformations,that were deep structure folding and right-lateral shear deformation along layer in the subduction period,mid-depth structure folding and high-angle progressive thrusting shear deformation in the collision period,shallow left-lateral sliding deformation and low-angle thrusting nappe structure in the intracontinental orogenic stage during late main orogenic epoch.Among them,the structures in the subduction and collision period had significant affection to gold mineralization in the district.The typical gold deposit-Ganheba gold deposit was studied in the area and the conclusion is that gold intial enrichment was formed by the shear deformation activity in the subduction period and the thrusting shear structure is a very important mineralized and controlled structure in the collision period,formed a series of ore shoots which plunge aligned parallel to shearing direction due to long time oblique shearing and thrusting activity.