论热液蚀变与铀成矿富集作用的关系

ON THE RELATIONSHIP BETWEEN HYDROTHERMAL ALTERATION AND URANIUM ENRICHMENT

本文通过对华南部分花岗岩型和火山岩型热液铀矿床中蚀变围岩物理-力学性质、铀浸出率及诱发裂变径迹的研究,阐明了热液蚀变对铀成矿富集的重要作用。热液蚀变能使岩石的抗压强度降低,有效孔隙度增高。矿前期蚀变作用可改变铀在含矿岩石中的赋存状态,使铀浸出率提高,为成矿热液提供部分铀源。一些蚀变围岩为铀沉淀富集提供了有利的地球化学环境。

According to the physicomechanical properties, uranium leaching tests and induced fission tracks of uranium for altered wall rocks of granite-type and volcanic-type hydrothermal uranium deposits in South China, this paper discusses the important role of hydrothermal alteration in the process of uranium metallogenic enrichment. 1. Hydrothermal alteration can cause the compressive strength of the rocks to decrease and the effective porosity of the rocks increase, therefore providing the channels and space for migration and deposition of ore-bearing fluids. 2. The pre-ore areal alteration may change the manner of occurrence of uranium in the ore-bearing rocks and thus increase the leachability of uranium, thereby supplying ore-forming fluids with a part of uranium. 3. The decrease of Eh in altered country rocks, such as pyritosericitized and chloritized rocks, may provide a favourable geochemical environment for uranium precipitation and enrichment. 4. Some altered minerals, such as hydromica, leucoxene and iron oxides, have high?adsorbability of uranium and become the collector of uranium.