湖南鲁塘煤系石墨矿区构造格局及控矿机制

The tectonic framework and controlling mechanism of coal-based graphite in Lutang mining area, Hunan Province

  • 摘要: 湖南鲁塘矿区为我国著名的煤系石墨矿区,煤系石墨的形成受岩浆热作用和构造作用的双重控制,其成矿和赋存都与构造格局密切相关。为深入研究构造作用对煤系石墨成矿的影响,通过野外地质调查和光学显微镜下观察、X射线衍射和拉曼光谱等测试分析方法,分析研究区构造特征和煤系石墨特征。研究结果表明,受区域构造活动的影响,鲁塘矿区构造格局呈现出分区分带性特征,东西方向可划分为东部、中部和西部3个条带;南北方向可划分为北部、中部和南部3个分区。自西向东,随着与岩体距离逐渐减小,煤层受岩浆热作用的影响逐渐增大,煤的石墨化程度也逐渐增高。由南向北,构造变形强度逐渐增强,导致北部分区形成以封闭式高温-高压的成矿环境为主,同时,应力作用促进了煤的石墨化,导致煤的石墨化程度较高;中部分区内构造情况复杂,形成不同温度压力条件的成矿环境,煤的石墨化程度差异性明显;南部分区构造情况简单,主要构成开放式环境,煤的石墨化程度较低,仅在近岩体附近可形成煤系半石墨。研究成果为煤系石墨资源勘探提供了有力依据。

     

    Abstract: Lutang mining area, one of the famous coal-based graphite mining areas in China, is controlled by both the magmatic intrusions and tectonic activities. Both the graphitization of coal and occurrence are closely related to the tectonic framework. To study the influence of tectonic activity on the formation of coal-based graphite, based on the filed geological survey, observation under microscope, X-ray diffraction and Raman spectroscopy experiments, structural characteristics of the research area and characteristics of coal-based graphite were analyzed. The effect of structural control of ore on the coal-based graphite was discussed in this paper. The tectonic framework of the study area is characterized by divisional and zonal structure due to the influence of regional tectonic activities. Three belts along the EW direction and three zones along the NS direction were divided separately. From the west to the east, the graphitization degree gradually increases with the decreasing distance from the intrusion. From the south to the north, the tectonic deformation degree is enhanced, resulting in the closed metallogenic environment in the northern zone which has high temperature and high pressure; moreover, tectonic stress promoted the coal graphitization, causing higher graphitization degree of coal. The complex tectonic condition in the central zone developed different temperature and pressure environment, which induced different graphitization degree of coal. In the southern zone, simple tectonic conditions tended to form open environment with the result of poor graphitization degree of coal. Semi-graphite occurs only occurred near the intrusion. The research provides a strong and convincing evidence for the exploration of coal-based graphite.

     

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