南秦岭旬阳烂木沟地区下志留统金矿地质特征及控矿因素浅析
Analysis on Geological Characteristics and Ore-controlling Factors of Silurian Gold Mine in South Qinling the Xunyang Lanmugou Area
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摘要: 旬阳烂木沟地区处于南秦岭造山带金及多金属成矿带的东段,该区下志留统经过多年的金矿勘查,找矿取得了一定突破,发现并探明了烂木沟金矿床。以往对烂木沟地区以西成矿带金矿地质特征、矿床成因、控矿因素的研究较多、观点各异,但对烂木沟地区金矿的相关研究报道甚少,为解决该区今后找矿中存在的实际问题,笔者在分析研究近年来烂木沟地区金矿勘查资料和科研成果的基础上,采用现代造山带理论,对金成矿区域构造背景、矿区地层、岩石、构造和地球化学特征进行了粗浅研究,指出下志留统第二岩性段黑色岩系是烂木沟地区金矿床形成的物质来源;南秦岭印支—燕山期陆内造山运动使巨型推覆断裂带之间的构造岩片发生大规模基底滑脱、逆冲推覆作用,是烂木沟地区金矿形成的动力学来源;黑虎庙韧性剪切带是烂木沟地区金富集成矿最主要的控矿因素,糜棱状石英黑云母片岩叠加黑云母化、硅化、黄铁矿化、褐铁矿化蚀变是该韧性剪切带的主要标志。Abstract: Xunyang Lanmugou area is in the eastern section of gold and polymetallic metallogenic belt of southern Qinling orogenic belt. After years of gold exploration in Lower Silurian series of this area, some prospecting breakthroughs has been made by having discovered and measured the Lanmugou gold deposit. Previous studies mainly focused on the geological feature, mineral deposit genesis and ore-controlling factors of the gold mine in the metallogenic belt west to Lanmugou area, few researches could be found on the gold mine of Lanmugou area. To solve the practical problems existed in the future prospecting, and on the basis of researches in the past few years, this paper adopts modern orogenic belt theory to study the tectonic settings, stratal, lithological, tectonic and geochemical characteristics of gold mineralization in this area. It is indicated that the Lower Silurian black rock series of second lithologic section is the material source of the gold deposit of this area. South Qinling Indosinian-Yanshanian intracontinental orogeny gave rise to the massive basement decollement and overthrusting of the tectonicslices between giant nappe fault zones, which was the source of dynamics in the formation of gold mine in Lanmugou area; Hehumiao ductile shear zone is the most important ore-controlling factor in the enrichment and metallization of gold mine in the Lanmugou area. Mylonitic quartz biotite schist overlying onto black mica alteration, quartz alteration, pyrite alteration and limonite alteration is the major sign of this ductile shear zone.
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