MINERALIZATION FEATURES OF THE GRANITE-TYPE URANIUM DEPOSITS IN SOUTHERN CHINA
MIN MAOZHONG;ZHANG ZUHUAN;ZHANG BANGTONG Department of Earth Sciences, Nanjing University
The present paper deals with the mineralization features of nearly 20 granite-type uranium deposits in Southern China. These features includ one in shape of ore bodies, host-rock alteration, mineralogical composition of ore, texture and structure of ore, mineralization type and paragenetic association of min- eral. It is shown that the granite-type uranium deposits in Southern China may be situated not only in granite bodies (i. e. interbelt-type), but also in an exocotact belts of granite bodies (i. e. exobelt-type). Shspe of ore bodies may be various and is essentially controlled by shape of fracture belts of host-rock and basic veins. Mineralogical compositions of ore are relatively simple. Pitchblende and coffinite are the most important original uranium minetals in this type of uranium deposits. The assemblage of gangue ore-minerals in exobelt-type uranium deposits is more complex than in interbelt-type uranium deposits. Most of minerals in ore are fine and Show gel texture. The ores of this type of uranium de- posits in form of veinlet-disseminative and brecciative. These features suggest tha mineralization of the granite-type uranium deposits in Southern China is characterized by low temoreture, rapid diposition and shallow ore-source. Kinds of host-rock alteration in this type of uranium deposits are many and varied. The degree of alteration, however, is rathr weack. Uranium mineralization in this type of deposits on- ly occurs in certain positions within area of hydrothermal face-type alteration of host rocks. Ore-rich bodies are generally located in the peition of strong line-type alteration of host rocks. Various face-type alterations of host rocks which are dispersed in a large limit are an important sign for search after the granite-type uranium deposits in Southern China.