西秦岭阳山金矿床控矿构造特征探讨

Discussion on the Ore-control Structural Features of the Yangshan Gold Deposit in the Western Qinling Belt

阳山金矿床位于西秦岭勉略构造内,文县弧形构造东翼,主要受安昌河—观音坝断裂带和葛条湾—草坪梁复式背斜控制;矿体产出于断裂带内,复式背斜翼部次级剪切走滑断裂中。研究表明:阳山金矿控矿构造及其演化复杂,泥盆纪中晚期文县地区形成了一套碳硅泥质热水沉积,勉略一带在三叠纪经历了洋陆俯冲到陆陆碰撞机制的转变;晚三叠世区内中酸性岩脉沿早期挤压片理侵入;早侏罗世早期,进入后碰撞造山期,断裂发生斜冲左行走滑剪切活动;燕山中晚期,进入局部伸展阶段,继承早期逆冲推覆构造,同时形成派生的断裂、节理及褶皱等。目前,所认识到的葛条湾—草坪梁复式背斜可能只是区域性复式褶皱北翼的次级褶皱。

The Yangshan gold ore locates in the west Qinling Mianlue slightly tectonic belt.Research area in the east wing of arc structure in Wenxian,was primarily controlled by Anchanghe-Guanyinba and duplex anticline.In addition,the ore body occurs in the fault zone as well as double anticline wing secondary shear strike-slip fault.On the basis of summarizing predecessors’research,combined with the detailed field geological observation,we found that the Yangshan gold deposit ore-controlling structure and its evolution were increasingly complex. Overall,the results indicated that it was formed a set of carbon silicon argillaceous hot water sedimentary in Wenxian during middle-late Devonian period.Mianlue area has experienced mechanism transformation from ocean-land subduction to continental collision in Triassic.Meanwhile,the double arc tectonic system in Wenxian county and nearly EW axial complex fold are formed,and intermediate-acid dike along the early extruded schistosity began to invade in the late Triassic.Early Jurassic entering into the collision orogenic period,breakage occurred the activity of oblique shock left-lateral slip shearing,and contacted with the same period of surrounding rock crushing,alteration.Moreover,mineralization was mainly dominated both by duplex anticline and left-lateral slip joint shear fracture zone.Early Yanshan period,it stretched into the local stage with the inheritance of thrust nappe structure,at the same time formed derived fracture,joint and fold,etc.At present,recognized by the Getiaowan-Caopingliang anticlinorium may only be a fold of the duplex folds north wing.