302铀矿床方解石C-O同位素组成与成矿动力学背景研究  

STUDY ON THE C-O ISOTOPIC COMPOSITION OF CALCITES AND METALLOGENIC DYNAMICS BACKGROUND IN THE NO.302 URANIUM DEPOSIT

作　　者：张国全[1,2] 胡瑞忠[1] 商朋强[1,2] 田建吉[1,2] 双燕[1,3] 

机构地区：[1]中国科学院地球化学研究所矿床地球化学国家重点实验室,贵州贵阳550002 [2]中国科学院研究生院,北京100039 [3]重庆地质矿产研究院,重庆400042

出　　处：《矿物学报》2008年第4期413-420,共8页Acta Mineralogica Sinica

基　　金：中国科学院知识创新工程重要方向项目(KZCX3-SW-125);国家自然科学基金重点项目(40634020)

摘　　要：302铀矿床规模大,垂幅深(达1000多米),是我国华南主要产铀花岗岩型铀矿床之一。研究表明该矿床的方解石是经大气降水与围岩发生水岩反应后的流体去气沉淀的;矿化剂∑CO2主要源自受控于岩石圈伸展导致的地幔去气,对铀成矿的作用一方面表现为加入到贫矿化剂的地下水中以便铀元素迁移,另一方面表现在从成矿流体中逸出,改变热液络离子组成,导致铀沉淀成矿;印支碰撞运动使华南地壳叠加增厚,部分熔融含铀结晶基底,为产铀岩体提供丰富的成矿物质来源;白垩纪-古近纪地壳拉张、岩石圈伸展所形成的深大断裂等不仅是矿化剂∑CO2主要通道,而且还是控制铀矿床形成的关键因素。：The No. 302 uranium deposit is big in scale and the vertical interval of ore-bodies extends about 1000 m. Thus, it is one of the main U-producing granite-type uranium deposits in South China. The results indicated that calcites were precipitated during fluid degassing after water-rock interaction between meteoric water and the wall rocks. The mineralizer ∑ CO2 mainly originated from mantle degassing which was controlled by lithospheric extension. Ura- nium could be transported easily after CO2 found its way into groundwater which was free from ∑ CO2. On the other hand, the anionic complex composition of fluid was changed when COz escaped from the ore-forming fluid, thus, U could be precipitated easily. The Indosinian collision movement caused the lithosphere thickened, leading to the formation of a partially melted uranium-bearing crystal basement in South China, therefore, it provided abundant oreforming materials for U-producing granites. Deep-large faults which were formed during lithospheric extension in the Cretaceous-Paleogene period were not only the main channels of mineralizer ∑ CO2, but also the key factors which controlled uranium deposition.

关 键 词：C-O同位素 动力学背景 岩石圈伸展 矿化剂 花岗岩型铀矿床 华南 

分 类 号：P578.6[天文地球—矿物学] P597[天文地球—地质学]