湘东北大洞-万古地区金矿构造成矿定位机制的初步研究

大洞—万古金矿区的成矿作用受到区域构造成矿的控制,即受到黄金洞—平江韧性剪切带的构造作用的控制;另一方面,矿区的二级构造已经成为燕山中晚期金矿的定位构造,即矿区北北西向断裂大部分是控矿、容矿构造。湘东北的陆内活化至少经历了陆内挤压和陆内拉张2个演化阶段,冷家溪群是金的矿源层,大洞—万古金矿区的构造成矿作用是主要成矿作用,金矿化是剪切带长期活动的结果。剪切带具有水平剪切和垂向推覆两种滑动作用,这就决定了金矿体在走向上和倾向上具有透镜体分布的特点。从万古金矿、鲁源洞金矿、大洞金矿矿脉在走向和倾向的产出形态可以看出,富矿体都产出在构造张性扩容空间内。

PRELIMINARY STUDY ON THE TECTONO-METALLOGENIC ORIENTATION MECHANISM OF THE DADONG-WANGU GOLD DEPOSIT ZONE, NORTHEASTERN HUNAN PROVINCE

The mineralization process in the Dadong-Wangu gold deposit zone is controlled by regional tectono-metallogenic unit, i.e., by the Huangjindong-P ingjiang ductile shear zone. On the other hand, the secondary structure of the D adong-Wangu gold deposit has evolved as the orientation structure for gold ores occurring in the middle to late Yanshanian orogeny, in other words, most of the NNW-striking faults are ore-controlling structures or ore-hosting structures . It was revealed in this paper that the intracontinental activation within Nort heast Hunan has experienced at least two stages of tectonic evolution (e.g., int racontinental compression and extension), the Lengjiaxi Group is the source bed for gold, the tectonometallogenic process is mainly responsible for the minerali zation in the Dadong-Wangu gold deposit zone, and the gold mineralization is re sulted from the long-term activities of the shear zone. The shear zone is chara cterized by two kinds of sliding action, e.g., horizontal shearing and vertical thrusting, which decide the characteristic distribution of gold ore bodies in th e form of lenticles in the directions of both strike and dip. It can be seen fro m the dip and strike directions as well as the morphology of the gold veins in t he gold mines that almost all ore shoots occur in tensile dilation spaces.