论华南层控铀矿床的类型

ON TYPES OF THE STRATABOUND URANIUM DEPOSITS IN SOUTH CHINA

本文以中国华南地区为例,根据大地构造条件及沉积建造特点,将层控铀矿床分为三大类,即地槽型海相沉积建造中的层控铀矿床、地台型海相沉积建造中的层控铀矿床和地洼型陆相沉积建造中的层控铀矿床。每一类按含矿岩石的性质不同,再进一步分为若干亚类。并对每类铀矿床的成矿地质背景及矿床特征,进行初步讨论。

Based on the tectonic settings and characteristies of the ore-hosting sedimentary formations, stratabound uranium deposits in South China have been divided into the following three types: 1. Stratabound uranium deposits in geosynclinal marine sedimentary formations. They are mostly found in Mount Xuefeng and its neighbouring areas and occur in the late Sinian to Early Cambrian geosynclinal marine unmetamorphosed or slightly metamorphosed carbonate rocks, siliceous rocks, pelitie rocks and their transitional rocks. Based on the geological settings, they can be subdivided into two subtypes: (1) stratabound deposits in the exocontact zone of Mesozoic granites. deposits of this type are of hydrothermal origin; (2) stratabound uranium deposits in areas with no or only weak magmatism: deposits of this type are of supergene leaching origin. 2. Stratabound uranium deposits in platformal marine sedimentary formations. They are distributed in the Hunan-Guangxi-Guangdong border region and occur in the late Paleozoic platformal marine carbonate rocks, siliceous rocks, carbonaceous-siliseous shales and elastic rocks. The uranium deposits were formed mainly by hydrothermal processes mixed with supergene reworking being of polygenetic type. 3. Stratabound uranium deposits in geodepression- (Diwa-)type terrestrial sedimentary formations. They include the following two subtypes. (1) Stratabound uranium deposits in terrestrial clastic sedimentary formations. They are distributed in various parts of South China and occur in the Mesozoic-Cenozoic geodepressiontype terrestrial sandstone and coal-bearing elastic rocks. Their origin is mainly due to supergene reworking mixed with hydrothermal processes. They belong to the epigenetic enrichment type. (2) Stratabouud uranium deposits in terrestrial volcanic-sedimentary clastiic formations. They are mainly distributed in Zhejiang, Jiangxi and Fujian and occur in the Late Jurassic geodepression-type terrestrial volcanic clastic rocks, lavas and volcanic-sedimentary rocks. The uranium mineralization is utterly different from that of the above-mentioned types, being related to terminal Mesozoic volcanic-hydrotherrnal activity.