湖南前震旦系铀矿化成因探讨

DISCUSSION ON THE GENESIS OF PRESINIAN URANIUM MINERALIZATION IN HUNAN

湖南前震旦系冷家溪群和板溪群是一套浅变质沉积岩,主要由各种板岩、变质砂岩、凝灰质板岩组成,夹有基性、中-酸性火山熔岩、火山碎屑岩及碳酸盐岩。现已落实铀矿床3个、矿(化)点14个。铀成矿年龄为85—50Ma,最晚者16Ma。稳定同位素研究结果表明,前震旦系铀矿化属岩浆岩源及沉积(变质)岩源中-新生代大气降水热液成因;铀矿化受断裂构造控制;凝灰质板岩、砂质板岩及角岩等是矿化有利的围岩。

Presinian system including groups of Lengjiaxi and Banxi in Hunan are a suite of epimetamorphic sedimentary rock and consist mainly of different metamorphic sandstones, slates and turfs in which the basic, intermediate-acidic volcanic lavas, pyroclastic rocks and carbonate rocks were intercalated. Up to now, 3 uranium deposits and 14 mineralized zones have been located The age of uranium mineralization was generally from 85 to 50 Ma, and the youngest 16 Ma. The stable isotope study from the ore shows that Presinian uranium mineralizations belong to Mesozoic-Cenozoic meteoric water in hydrothermal origin, uranium of which was originated from magmatic rocks(granites) and Presinian sedimentary(metamorphic) rocks. The uranium mineralizations were controlled by the fault structures. Tuffaceous slate, sandy slate and hornstone, etc. are considered as favourable country rocks for mineralization.