湖南加里东期花岗岩成因及铀成矿关系

华南出露大量加里东期花岗岩，其岩石成因、构造背景长期存在争议。湖南省加里东期花岗岩年代学和地球化学数据显示，其主要形成于416～432 Ma之间，岩性主要为花岗岩和花岗闪长岩。岩石类型除少数为I型花岗岩外，大部分为S型花岗岩。地球化学特征为富硅、过铝质和高钾钙碱性系列花岗岩，富集Rb、Th、U等元素，亏损Ba、Nb、Sr等元素；指示岩浆源区为古-中元古代地壳物质部分熔融的产物，部分花岗岩有幔源物质的加入。区域地质背景和岩石地球化学数据指示湖南加里东期岩体形成于碰撞挤压峰期之后挤压减弱、应力松弛的后碰撞构造环境。区域内加里东期花岗岩中铀含量相对较高，为后期铀成矿提供物质来源。

Genesis of Caledonian Granites and Uranium Metallogenic Relationship in Hunan

A large number of Caledonian granites have been exposed in South China, and their petrogensis and tectonic setting have been controversial for a long time. The Chronology and geochemical data of Caledonian granite show that it was mainly formed between 416 and 432 Ma, and the lithology is mainly granite and granodiorite. Except for a few I-type granites, the majority of Caledonian granites are S-type granites. Geochemical characteristics show that the granite is rich in silicon, peraluminum and high-potassium calcium alkaline granite, enriched in Rb, Th, U, Pb, K and other elements, and depleted in Ba, Nb, Sr, P, Ti and other elements. It is the product of partial melting of Paleo-Middle Proterozoic crustal materials, and some granites have mantle-derived materials. Regional geological setting and petrogeochemical data indicate that the Caledonian rock mass in Hunan was formed in a post-collision tectonic environment with weakening of extrusion and stress relaxation after the peak period of collision extrusion. The Caledonian granite in the region has relatively high uranium content, which provides material source for later uranium mineralization.