略论矿区的引裂构造

一、引裂构造概念不论成矿物质来源如何,地质构造总是形成矿床的必备条件之一,对于内生和复生矿床来说,特别重要的条件是断裂构造。与成矿有关的断裂,按其规模和控矿特点,大致可以分成三大类:①区域深大断裂,一般与岩浆-成矿域(带)相联系;②地区性大断裂,制约岩石-成矿区(带);③矿区性断裂,控制矿田、矿床和矿体的空间展布。本文提出的引裂断裂构造,属矿区构造。所谓引裂构造,是说断裂的控矿机制在于引生次一级或次多级的容矿裂隙,断裂与裂隙构成矿区的成矿断裂构造系统,视断裂-裂隙的级数多少而可分别称为二级或多级成矿断裂

A Brief Discussion On The Fracture-Leading Structure

The fracture Jeading structure is the structure which controls the spatial distribution of ore fields, ore deposits and orebodies. As for its significance in mineralization, there exist a variety of views. The author considers that its controlling mechanism lies in the derivation of secondary ore-hosting fissures. Therefore, it is called fracture-leading structure. The ore-forming fracture system is made up of fractures and fissures. The fracture-leading structures so far observed can be classified into four types: individual fractures two or more fractures that are approximately parallel to each other; rhombic or tetragonal structures formed by two groups of structures and the broom-like structures consisting of several fractures. The fracture-leading structures commonly occur as fractured zone, belonging to compression-shear or compression structures and formed at mineralization stage. The structural activities have a close connection with mineralization. The fillings in fractures are dominantly the breccias of wall rocks, which contain no orebody or no large orebody, but have experienced mineralization and alterations of different degrees. In the fractures and their adjacent wall rocks, several sorts of geochemical anomalies have been detected, e. g., the primary halo of metal elements or of volatile elements and the soil mercury dispersion halo. The ore-hosting fissures on the sides of the fracture appear in a single group and one direction or in numerous groups and various directions. In general, there exist three modes of occurrence: steeply-dipping fractures cutting through the layers or fissure zones, interstratal fractures or the intrastratal netted fissures. The ore-hosting fissures are usually asymmetric on both sides of the fracture, i. e., those in the upper wall is more developed than those in the lower wall. In reconnaissance and prospecting, we should first recognize the fracture-leading structure in the working district on the basis of geological and geochemical characteristics, then seek mineralization localities along this structure, especially along its upper wall. Finally, based on the metallogenic conditions, the controlling mechanism of fractures and various ore-forming indications, we can infer the type of deposits that we are likely to find, and the scale and degree of mineralization.