赣南黄沙矿区辉绿岩Ar-Ar年龄及其与铀成矿关系

Ar-Ar age of the diabase and its relationship with uranium mineralization in Huangsha mining district,southern Jiangxi Province

赣南黄沙矿区是一个有较大找矿远景的花岗岩型铀矿区。矿区内辉绿岩脉发育,呈NW向似帚状分布,部分辉绿岩脉控制了铀矿体的产出形态,其中取于良伞寨矿床坑道中的辉绿岩样品,测得Ar-Ar年龄140Ma左右,该年龄明显早于黄沙矿区铀成矿年龄。黄沙矿区辉绿岩与铀矿化没有时间上的关联,但有较密切的空间关系,主要表现为三种型式,一是铀矿化直接产于辉绿岩脉内部,受辉绿岩内部碎裂蚀变带控制,二是铀矿化产于辉绿岩脉的外侧,或其走向延伸方向,受辉绿岩之围岩花岗岩中的碎裂蚀变带控制,三是铀矿化产于辉绿岩与硅化带的复合地带,受发育于辉绿岩中的规模不一的硅化带控制。辉绿岩之所以与铀矿化有密切的空间关系,主要是因为辉绿岩可为铀成矿提供一个有利于铀沉淀富集的物理化学环境。

Huangsha mining district in southern Jiangxi province is a great prospecting area for granite type uranium,where diabasic dike develops and distribute as brush in the northwest part,and some of the diabase veins control the output form of the uranium orebody.The Ar-Ar age of diabase sample taken from the gallery in Liangsanzhai deposit is about 140 Ma,which is obviously earlier than uranium mineralization age.There is no time correlation between diabase and uranium mineralization,but a closer spatial relationship in the district.There are three main performance forms：（1）Uranium mineralization is produced directly in the diabase vein,controlled by the fractured alteration zone in the diabase.（2）The uranium orebodies are developed in the lateral of the diabase,or its strike extension direction,and are controlled by the fracture alteration zone in the granite of the diabase surrounding rock.（3）Uranium mineralization is produced in cross composite strip of the diabase and silicide zone,which is controlled by the different silicified belts in the diabase.There is a close spatial relationship between diabase and uranium mineralization,mainly because diabase can provide a physical and chemical environment for uranium mineralization and enrichment of uranium.