甘肃岷—礼成矿带钨矿地质特征及找矿方向
Geological features and prospecting direction of Tungsten deposits in the Min-Li metallogenic belt, Gansu Province
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摘要: 通过对岷—礼成矿带寨上钨矿床和雪坪沟钨矿床地质特征及其与成矿有关的岩(脉)体进行对比研究,分析岩(脉)体的成矿专属性,结合区域地质背景,探讨该成矿带钨矿床的找矿方向。寨上钨矿床和雪坪沟钨矿床分别为破碎蚀变岩型和隐爆角砾岩型钨矿床,其成矿物质来源于岩浆期后热液,时空和成因与同时代的岩(脉)体密切相关,是晚三叠世(220~210 Ma)岩浆作用及其过程的产物。“五朵金花”岩体群属富钨的“S”型花岗岩类,具有相似的地球化学特征和同源性,其分布范围与W、Sn、Mo、Bi、Be组合异常吻合,是岷—礼成矿带找钨的首选找矿靶区。建议围绕(隐伏)岩(脉)体,重点开展常家山、梅川W异常查证,寻找新矿床(体)。Abstract: This study carried out a detailed comparative analysis of geological features and mineralization-related intrusion or dykes in the Zhaishang tungsten deposit and the Xuepinggou tungsten deposit, both of which are distributed along the Min-Li metallogenic belt in West Qinling. In conjunction with the regional geological features, metallogenic characteristics of rocks and related dykes were discussed to better understand the prospecting direction of tungsten mineralization in this area. The results show that the two deposits belong to the broken alteration rock type and cryptoexplosive breccia type tungsten deposits respectively, with ore-forming material derived from post-magma hydrothermal fluids. Their genesis was closely related to contemporaneous rocks or dykes in terms of time and space. The two deposits should be the products of magmatic activities during the Late Triassic(220~210 Ma). “Five Golden Flowers” intrusion group belongs to W-rich S-type granite, with similar geochemical characteristics and homology. In addition, its distribution is in agreement with anomalous areas of W, Sn, Mo, Bi and Be element combination, indicating that the intrusion group should be the preferential target for prospecting tungsten deposits in the Min-Li metallogenic belt. Therefore, this study suggests that prospecting should be concentrated on tungsten anomalous fields in the Changjiashan and Meichuan areas containing intrusions(dykes)so as to search new orebodies or deposits.