长江中下游成矿带安庆-贵池矿集区五横岩体的成岩年代和区域岩浆活动演化研究

五横岩体是长江中下游成矿带中安庆-贵池矿集区月山矿田内重要的中酸性侵入岩体之一。本文对五横岩体中1个辉长闪长岩、3个闪长岩和1个二长闪长岩样品进行了锆石LA-ICP-MS U-Pb定年,得到年龄值为分别为139.6±1.6Ma、139.3±1.3Ma、140.1±1.4Ma、140.0±1.6Ma以及132.9±1.5Ma,表明闪长岩和二长闪长岩为不同期岩浆作用的产物。结合地质特征,将五横岩体划分成两个不同的岩体。基于区内已有的岩石学、地球化学和成矿年代学研究,将月山矿田内侵入岩划分为两期,早期侵入岩主要为闪长岩类,成岩时代为138~140Ma;晚期侵入岩主要为花岗岩和正长岩,具有A型花岗岩的地球化学特征,成岩时代123~126Ma。通过对比分析,认为五横岩体具有较好的矽卡岩型铜金铁矿床成矿潜力,其成岩成矿作用过程发生于区域挤压-拉张过渡的构造背景。

Petrogensis chronology and evolution of regional magmatic activity study of Anqing-Guichi ore deposit concentrated area in the Middle-Lower Reaches of Yangtze River metallogenic belt

Anqing-Guichi ore deposit concentrated area is located in the Middle-Lower Reaches of Yangtze River fault-depression zone, where is the north margin of the Yangtze Block. The Wuheng intrusion is the one of the most important intermediate-acid intrusive body in the Yueshan ore field, Anqing-Guichi ore deposit concentrated area. In this paper, we present LA-ICP-MS U-Pb zircon age of 139.3±1.3Ma, 140.1±1.4Ma, 140.0±1.6Ma for diorite, 139.6±1.6Ma for gabbro-diorite and 132.9±1.5Ma for monzodiorite. The epoch of intrusion suggests that diorite and monzodiorite are the products of magmatism in different period. Combined with geological characteristics, Wuheng intrusion should be divided into two different parts. On the base of an integrated study of available petrological, geochemical and diagenetic chronology of magmtic rocks in Yueshan ore field, we divide intrusion into two period, early intrusive rock are mainly diorite, diagenetic age is about 138~140Ma; late intrusive rock are mainly granite and syenite, which have geochemistry characteristics of A-type granite, is about 123~126Ma. Wuheng intrusion has preferably metallogenetic potentiality of skarn Cu-Fe-Au deposit, which took place in a transitional tectonic environment from compression to extension.