安徽安庆地区五横岩体地质特征及成矿潜力
Geological characteristics of the Wuheng intrusion in Anqing, Anhui Province and its mineralization potential
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摘要: 安庆地区位于长江中下游多金属成矿带中段,是内生金属矿床找矿重点地区之一。通过研究五横岩体岩石学、地球化学及热液蚀变特征,并与邻近地区的月山岩体进行对比,进一步评价五横岩体的成矿潜力。结果表明:安庆地区五横岩体与月山岩体均属于中酸性侵入体,五横岩体与浅部金铜热液脉型矿化关系密切,月山岩体与铜、金等多金属成矿关系密切。五横岩体具有由辉长闪长岩向二长岩演化的岩相学特征,月山岩体主要由闪长岩、二长闪长岩和石英闪长岩组成。五横岩体蚀变强烈,蚀变分带明显,其中低温蚀变带多数伴有铜、金矿化,具有较好的热液系统成矿潜力,月山岩体具有较完整的矽卡岩-热液脉型成矿系统,具有形成较大规模铜铁矿床的潜力。五横岩体与月山岩体在岩石成因、构造背景和热液蚀变等方面具有相似性,深部与三叠纪灰岩接触带可能具有寻找矽卡岩型矿床的潜力。Abstract: The Anqing area located in the middle segment of the middle-lower Yangtze River polymetallic metallogenic belt is one of the critical regions for exploration of polymetallic deposits. In order to evaluate metallogenetic potential of the Wuheng intrusion, petrology, geochemistry and alteration characteristic of the Wuheng intrusion were studied and compared with that of the Yueshan intrusion. The results show that both the Wuheng and Yueshan intrusions in the Anqing area belong to intermediate-felisc rocks. The Wuheng intrusion is closely associated with gold and copper hydrothermal vein-type mineralization, while the Yueshan intrusion with copper, gold and other polymetallic mineralization. In addition, the Wuheng intrusion is lithologically characterized by transion from pyroxene diorite to monzodiorite, and the Yueshan intrusion consists mainly of diorite, monzodiorite and quartz diorite. Intensive hydrothermal alteration in the Wuheng intrusion shows obvious alteration zones. Among them the moderate-low temperature alteration zone is associated with mineralization of copper and gold in particularly, displaying significant potential of hydrothermal metallogenic system. The Yueshan intrusion shows relatively complete skarn-hydrothermal vein-type metallogenic system, which has potential to form large-scale copper and iron deposits. It is concluded in this study that the Wuheng and Yueshan intrusions are similar in terms of petrogenesis, tectonic setting, and hydrothermal system, and deep contact zones of the Wuheng intrusion with Triassic limestone might have potential for exploration of skarn-type mineralization.