广西栗木矿田锡钨成矿条件和成矿过程分析

Analysis of the Metallogenic Geological Conditions and Metallogenic Process of Tin-tungsten Deposits in Limu Orefield,Guangxi Province

栗木矿田锡钨矿床与花岗岩体的多期次侵入有着密切关系,而花岗岩体的侵入形态又受限于构造、地层等因素。因此,成矿地质条件与成矿过程的分析与总结,对于成矿预测、找矿潜力评价等找矿勘查工作至关重要。针对栗木矿田地层、构造、岩浆岩三要素进行了成矿地质条件分析,揭示了三要素对成矿作用的影响,并探讨了成矿作用的关键过程与机制。研究表明:①花岗岩的含矿性既与初始岩浆的含矿性有关,又与岩浆演化过程中的气液分异程度及构造活动强度有关。②矿床分布明显受隐伏岩体形态影响,而隐伏岩体形态又受基底构造层断裂和盖层断裂控制。③岩体上覆围岩地层的岩性对形成的矿床类型及矿化蚀变分带有明显的制约,上覆围岩为灰岩、大理岩,有利于形成完整的矿化垂向分带;上覆围岩为页岩、硅质泥岩和泥灰岩,仅有利于形成岩体内带石英脉型钨锡矿,不利于其他类型矿床形成;上覆围岩为砂岩,介于两者之间;④矿区成矿过程是岩浆热液在地层、构造、岩浆三要素控制下的综合反应。上述分析可作为勘查技术组合分析的主要地质依据,指导隐伏花岗岩型锡钨矿床的找矿预测和勘探。

The tin-tungsten deposit in Limu Orefield is closely related to the multi-stage intrusion of granite. Meanwhile,the intrusive form of granite is limited by the influence of structure and stratum. It is necessary to analyze and summarize the metallogenic geological conditions and metallogenic process,which is very important for prospecting and exploration work such as metallogenic prediction and prospecting potential evaluation. In this paper,the metallogenic geological conditions are analyzed based on the stratum,structure and magmatic rock in Limu Orefield,the influence of the three factors on mineralization is revealed. In addition,key process and mechanism of mineralization in Limu Orefield are discussed. The study results show that:(1) The mineralization of granite is related not only to the mineralization of initial magma,but also to the degree of gas-liquid differentiation and the intensity of tectonic activity in the process of magma evolution.(2) The distribution of tin-tungsten deposit is obviously influenced by the shape of concealed intrusive bodies,which is controlled by the faults of the basement structure layer and the cover layer.(3) The lithology of overlying rock strata has obvious constraints on the types of tin-tungsten deposits and mineralization alteration zoning:If the lithology of overlying rock strata is limestone and marble,it is conducive to complete mineralization vertical zoning;If the lithology of overlying rock strata is shale,siliceous mudstone and marlite,it is only conducive to the formation of quartz vein type tin-tungsten deposits within the rock body,which is not conducive to the formation of other types of deposits;If the lithology of overlying rock strata is sandstone,it is between them.(4) The metallogenic process is a comprehensive reaction of magmatic hydrothermal solution under the control of stratum,structure and magma. In short,the above research results can be used as the main geological basis for the combination analysis of exploration technology,and guide the prospecting prediction and exploration of concealed granite deposits.