黔西北五指山穹状背斜构造特征与控矿模式

Structural Characteristics of the Wuzhishan Dome-Shaped Anticline,Northwest Guizhou,China and Its Ore-Controlling Model

黔西北地区位于上扬子板块西南缘,是华南大面积低温成矿域的重要组成部分之一。该区东南部的五指山穹状背斜控制着多个铅锌矿床,显示其与铅锌成矿作用有密切联系。本文以五指山穹状背斜为研究对象,通过详细的地质调查与构造解析,结合不同时代地层白云岩的微量元素地球化学分析,揭示五指山背斜的的构造样式及其控矿模式。不同时代地层白云岩中的Pb、Zn、As、Ag和Sb富集特征,显示围岩中的成矿元素有一定程度富集,但围岩可能不是主要的金属物源岩石。综合区域地质背景资料,本文认为五指山地区铅锌矿床的成矿物质主要来自基底岩石,成矿流体在断裂的运移过程中,由于岩性界面和流体压力等作用,在有利部位富集成矿,而五指山地区有利的穹状背斜-逆冲断裂构造样式,就是铅锌成矿的最有利部位。

The NW Guizhou is in the southwestern edge of the Upper Yangtze Block and is one of the important components of the giant low-temperature metallogenic domain in South China. Several lead-zinc deposits are controlled by the Wuzhishan dome-shaped anticline in the southeastern part of the area, indicating that the Wuzhishan anticline is closely related to the Pb-Zn mineralization. In this paper, the Wuzhishan dome-shaped anticline is selected as the research object. Through detailed geological survey and structural analysis, and the trace element geochemical analysis of the dolomite in different aged strata, we have revealed the structural style and Pb-Zn ore-controlling model of the Wuzhishan anticline. The enrichment characteristics of Pb, Zn, As, Ag, and Sb in dolomites of various aged strata suggest that those ore-forming elements are enriched in wall rocks in a certain degree, though the wall rocks could not be the main metal source rocks. Based on the comprehensive study of regional geological background data, we have considered that the ore-forming materials of the Pb-Zn deposits in the Wuzhishan area could be mainly sourced from the basement rocks. During the migration process of the ore-forming fluids via fractures, because of lithological interface and fluid pressure, the mineralization occurred in some favorable locations. The favorable structural style of dome-shaped anticline and reverse fault in the Wuzhishan area is the most favorable part for the Pb-Zn mineralization. Based on the geological and geochemical research data, we have finally established an ore-controlling model for the anticline in this paper.