The characteristics, evolution and enlightenment of uranium mineralization in Xiangshan ore-field, Jiangxi Province

Finding the rich and large hard rock type uranium deposits has always been a challenge.Using some new ideas to study the characteristics of some known rich and large uranium deposits and to explore constantly their mineralization process may bring some new understanding.According to the metallogenic mechanism by coupling the deep and large fault with the critical water, this paper has re-analyzed the characteristics and metallogenic process of uranium deposit in Xiangshan magmatic complex uplift, and explores the common law of the rich and large hydrothermal deposit by combining with the research of other rich and large hydrothermal deposits.These rich and large hydrothermal deposits have the following characteristics: First of all, there is often the shape of "one knife overlying one cake" formed by combining the deep and large fault with the magmatic complex uplift.This deep and large fault with the shape of a knife is a multi-stage activity.Due to the pressure reduction, temperature rise and water accumulation, this fault will change the physical-chemical environment of the surrounding area, which drives the material migration and phase transformation related to the mineralization, so as to control the formation of the magmatic complexes uplift, hydrothermal alteration and uranium mineralization stages.Secondly, there are usually three main tectonic layers and their corresponding three-stage evolution.Thirdly, there are alway two main mineralization stages in the rich and large hydrothermal deposits.The early high-temperature mineralization stage(115±0.5 Ma in Xiangshan ore field)is related to the formation of magmatic complex, while the late low-temperature mineralization stage(98±8 Ma in Xiangshan ore field)is related to the basin-controlling fault activity and basin dehydration.The superposition of the two stages of mineralization is a necessary condition for the formation of rich and large ore bodies.These above characteristics are mainly reflected in the structural and lithologic combination composed of deep and large faults and magmatic complex uplift with the shape of "one knife overlying one cake", which their formation mechanism is still the multi-stage diagenesis and mineralization by activity of the deep and large faults in essence.These understandings may bring some enlightenment to the study of mineralization and prospecting of rich and large hydrothermal uranium deposits in China.