湘东茶陵地区老山坳剪切带特征及其与湘东钨矿的关系

发布时间：2018-06-05 03:21

本文选题：湘东钨矿 + 老山坳剪切带　；参考：《岩石学报》2016年05期

【摘要】：湘东茶陵地区老山坳剪切带及其与湘东钨矿的关系是长期以来备受关注且颇具争议的问题。其争议主要表现为:(1)老山坳剪切带(断层)的性质(逆断层、正断层,还是走滑断层)及其发育机理;(2)老山坳剪切带对湘东钨矿的成矿是促进作用还是破坏作用。本文对老山坳剪切带以及湘东钨矿进行了系统地观察和测量,采用宏观、微观构造研究和矿脉统计相结合的方法进行了综合分析。结果表明,老山坳剪切带的活动主要分为两期:早期主要表现为向SE方向的伸展拆离作用,且可能与晚侏罗世八团岩体侵位密切相关,形成了透入性的强烈脆、韧性变形,特别是在糜棱岩中,由于高压流体的作用造成了一系列同期节理(R和R’节理)发育,为石英脉型钨锡矿床的形成提供了条件;后期,大致在晚白垩世及之后老山坳剪切带表现为向NW方向的逆冲作用,致使上盘(主动盘)的钨锡矿脉被推至浅部。因此,我们认为晚侏罗世八团岩体的侵位作用与老山坳剪切带的伸展拆离作用共同控制了湘东钨矿的形成。韧性剪切带中,由于高压流体作用引起局部应变速率增加,同时降低岩石强度而发生脆性破裂(如T节理,R和R’节理),而且按照破裂准则发生和扩展,该过程为成矿元素析出成矿提供了条件,这可能是剪切带成矿的重要方式之一。
[Abstract]:The Laoshan depression shear zone in Chaling area of eastern Hunan and its relationship with the tungsten deposit in eastern Hunan province have long been a subject of much concern and controversy. The dispute mainly shows that the character of Laoshan depression shear zone (thrust fault, normal fault or strike-slip fault) and its development mechanism are Laoshan depression shear zone to promote or destroy the mineralization of Xiangdong tungsten deposit. In this paper, the Laoshan depression shear zone and the tungsten deposits in eastern Hunan have been systematically observed and measured, and the method of combining macroscopic and microstructural studies and vein statistics has been used to conduct a comprehensive analysis. The results show that the activities of the Laoshan depression shear zone are mainly divided into two stages: the early stage is mainly characterized by extensional detachment in the direction of SE, which may be closely related to the emplacement of the eighth block rock mass in the late Jurassic, resulting in strong brittle and ductile deformation of permeability. Especially in mylonite, a series of synchronal joints R and R 'joints developed due to the action of high pressure fluid, which provided the conditions for the formation of quartz vein type tungsten tin deposits. During the late Cretaceous and later Laoshan depression shear zone appeared as a thrust in the direction of NW which resulted in the Tungsten-tin ore veins in the upper disc (active disk) being pushed to the shallow part. Therefore, we think that the formation of Xiangdong tungsten deposit was controlled by the emplacement of the late Jurassic Bichang rock mass and the extension and detachment of the Laoshan depression shear zone. In the ductile shear zone, brittle fracture (such as T joint R and R 'joint) occurs due to the increase of local strain rate due to the action of high pressure fluid and the decrease of rock strength. This process provides the conditions for the precipitation and mineralization of ore-forming elements, which may be one of the important ways of metallogenic in shear zone.
【作者单位】：中国科学院计算地球动力学重点实验室中国科学院大学地球科学学院;中国地质大学地球科学与资源学院;湖南省地质矿产勘查开发局四一六队;
【基金】：国土资源部公益项目(201211024-04) 国家自然科学基金项目(41502215)联合资助
【分类号】：P542;P618.67

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