皖东苏家湾地区三里陈岩体LA-ICP-MS锆石U-Pb年代学研究

LA-ICP-MS zircon U-Pb age dating of the Sanlichen intrusion in the Sujiawan region, eastern Anhui

关键词:  闪长岩  LA-ICP-MS锆石U-Pb定年  皖东苏家湾地区  三里陈岩体

Key words:  diorite  LA-ICP-MS zircon U-Pb age dating  Sujiawan region in eastern Anhui  Sanlichen intrusion

摘要:

三里陈岩体位于长江中下游成矿带滁县-庐江铜金成矿亚带中部，岩性主要为闪长岩和花岗闪长斑岩，LA-ICP-MS锆石U-Pb定年测得闪长岩年龄为126.9±1.8Ma，花岗闪长斑岩锆石U-Pb年龄为126.0±1.0Ma，两者均为早白垩世岩浆活动的产物。闪长岩中存在的大量继承锆石的年龄分布在2.5~1.9Ga之间，峰值为2.0Ga，暗示其岩浆源区主要为华南板块，可能混有华北板块源区的物质。结合滁县-庐江铜金成矿亚带成岩时代及矿化特征，发现三里陈岩体与铜金矿床（点）成矿岩体的形成时代相近，岩性一致，与围岩接触带发育的蚀变和矿化特征相似，认为这些侵入岩体均为同一构造-岩浆-成矿事件的产物，三里陈岩体及其外围地区具有寻找一定规模矽卡岩型铜金矿床的潜力。

Abstract:

The Sanlichen intrusion is located in the central part of the Chuxian-Lujiang copper-gold metallogenic subzone in the Middle-Lower Yangtze River Valley metallogenic zone, where diorite and granodiorite are accentuated. The present paper presents two groups of high-resolution zircon U-Pb ages:126.9±1.8 Ma for the diorite and 126.0±1.0 Ma for the granodiorite. Both the diorites and granodiorites are originated from the Early Cretaceous magmatic activity. The inherited zircon U-Pb ages mainly range from 2.5 to 1.9 Ga, and the peak age is about 2.0 Ga. These data show that the magmas may be derived from the South China plate, with the mixtures of the North China plate. The similarities in mineralization age and lithology between the Sanlichen intrusion and the copper-gold deposits, and those in alteration and mineralization between the Sanlichen intrusion and the country rocks show that the intrusive rocks should be the products of the same tectonic-magmatic-mineralization events. The Sanlichen intrusion and its surrounding areas are believed to be prospective for the exploration of the skarn-type copper-gold deposits.