甘肃小独山西钨矿床成因探讨

小独山西钨矿床是近年来新发现的大型钨矿床,笔者从地层、构造、岩浆岩、蚀变作用等成矿条件入手,对该矿床的成因进行了探讨。该区地层、构造、岩浆岩条件的完美耦合是该矿床形成的根本原因。矿区下二叠统红柳河组各岩性层中钨元素丰度值高,为该矿床的形成创造了物质条件;矿区极其发育的断裂裂隙系统,为后期成矿热液的运移、物质交换、成矿元素的沉淀富集提供了通道及储存空间;燕山早期的岩浆活动,在为成矿提供热源、物源的同时,使得早期的断裂裂隙系统再次活动,为成矿热液的运移、物质交换、成矿元素的沉淀富集开辟了更为广阔的通道及储存空间;燕山早期岩浆期后热液沿着前期形成的断裂裂隙充填交代,在高温阶段形成石英脉脉型黑钨矿,随着温度的逐渐降低,形成石英脉脉型白钨矿;原生矿床形成后,经过长期的表生作用,进一步次生富集形成沿沟谷产出的钨砂矿。小独山西钨矿床是与酸性岩浆活动有关的充填交代式石英细脉带型(黑)白钨矿矿床。寻找成矿热液运移通道及其方向,将成为今后该区找矿工作的重点。

Xiaodushanxi Tungsten Deposit's Mineralization Mechanism

This paper discusses the mineralization mechanism of the large-scaled Xiaodushanxi tungsten deposit from the conditions of stratigraphy, tectonics, magmatic rocks and wall-rocks alteration. The above conditions perfect coupling is the fundamental reason for the formation of this deposit. Material condition provides by Lower Permian Hongliuhe group lithology layer for its high tungsten value. Extremely fractured fault systems provide the channel for migration of the later ore-forming hydrothermal, and provide the access and storage space for ore- forming material exchange, sediment-rich and mineralization. Yanshan early magmatic activity provide heat and material sources, at the same time, the early fracture systems＇ re-activities provide a wider channel and storage space for the hydrothermal migration, material exchange, mineralization. Yanshan early post-magmatic hydrothermal filled and exchanged along the pre-formed account of fractures. In the periods quartz-type wolfram formed under high-temperature phase, and quartz-type scheelite formed with the gradual lowering of temperature. After formation of the deposit, placer tungsten formed along the valley by weathering for a long time. So the deposit is a filling-replacement wolfram and scheelite deposit related to acidic magma. Searching for ore-forming hydrothermal migration pathway and its direction will become the working focus in the future prospecting in this area.