安徽铜陵地区晚中生代早、晚两期侵入岩的地质和地球化学特征

安徽铜陵地区是中国东部长江中下游构造-岩浆-成矿带中的一个重要矿集区，区内铜金多金属矿床与晚中生代 （燕山晚期） 岩浆作用具有密切的成因联系。以往研究认为，铜陵地区侵入岩的同位素地质年龄集中于147~135 Ma区间， 结合最新的同位素地质年龄测定发现，铜陵地区还存在部分锆石U-Pb年龄介于132~124 Ma间的侵入岩。因此，将铜陵地 区晚中生代侵入岩划分为早、晚两期，对应的地质时代分别为晚侏罗世-早白垩世和早白垩世。文章系统对比和研究了铜 陵地区早、晚两期侵入岩的岩石类型、产状、空间分布等地质特征，以及主量、微量和稀土元素地球化学特征，并对比长 江中下游构造-岩浆-成矿带宁芜地区和庐枞地区火山-侵入岩，认为铜陵地区晚中生代早晚两期侵入岩分别形成于陆内 挤压-伸展过渡和伸展的构造应力背景之下，晚期侵入岩是早期岩浆房中的岩浆再次侵位和深部地壳进一步熔融岩浆侵位 形成的，与之相应的成矿作用不容忽视。

Geological and Geochemical Characteristics of the Intrusive Rocks of Early and Late Stages during Late Mesozoic in Tongling District,Anhui Province

The Tongling district of Anhui Province is an important ore concentrating area in the tectonic-magmatic-metallogenic belt of the middle and lower reaches of Yangtze River in eastern China. The copper-gold polymetallic deposits in this area are closely related to the Late Mesozoic (Late Yanshanian) magmatism. Previous studies have suggested that the isotopic ages of intrusive rocks are concentrated in the range of 147-135 Ma. Based on the new zircon U-Pb dating results, this study found that there are a small amount of intrusions were formed between 132-124 Ma. Therefore, according to these new age data of the intrusive rocks, the magmatism during the Late Mesozoic in the Tongling district can be divided into two stages, corresponding to Late Jurassic-Early Cretaceous and Early Cretaceous, respectively. This paper has systematically studied the geological characteristics of the two stage intrusive rocks, including rock types, occurrences and spatial distribution, and geochemical characteristics of major, trace and rare earth elements. By comparing these two stage intrusive rocks with the volcanic-intrusive rocks in Ningwu and Luzong basins, it is concluded that the early and the late stage magmatism were generated under a transitional setting from compression to extension and an extensional setting, respectively. The late stage intrusive rocks were formed jointly by re-emplacement of magma from the early stage magma chamber and magma from further partial melting of the deep crust. The significance of the mineralization related to the late stage intrusion can not be ignored.