湖南省铀矿床类型、成矿系列成矿谱系与找矿新进展

本文在《中南铀矿地质志》、《中国矿产地质志·湖南卷铀矿》的基础上,系统梳理湖南铀矿勘查和科研成果,总结了湖南铀矿成矿规律。将湖南铀矿床划分为热液型、海相沉积型、陆相沉积型等3大类4类10个亚类。总结了铀矿时空分布特点,成矿地质背景和同位素年龄表明,控岩控盆控矿构造与岩浆、火山和热液活动集中发生在晚白垩世至古近纪,主成矿期为晚白垩世;重要铀矿床均分布在中新生代断陷盆地周边及盆地中,区域上铀成矿受铀独特的地球化学性质和统一的区域构造演化特定时期陆内裂谷阶段或区域断陷盆地阶段的制约,反映了铀区域成矿作用内在的时空统一性。厘定了湖南省内以铀为特色的矿床成矿系列,共划分2个成矿系列组合,7个成矿系列,8个成矿亚系列;衡阳盆地以铀为特色的矿床成矿系列的复合,是本次研究的重要成果,有助于揭示铀区域成矿作用内在的时空统一性;分析了铀成矿演化特征,构建了铀成矿谱系。近年来,应用成矿系列理论在重点铀成矿区开展找铀和关键矿产的综合找矿,取得重要找矿成果,建立了金银寨式、鹿井式等13个铀矿矿床式。提出在重点铀成矿区主攻热液型中大型铀矿床的同时,要重视大吨位岩体型铀矿(斑岩型、白岗岩型、花岗伟晶岩型)的找矿探索工作以及铀成矿区关键矿产的综合找矿和第二找矿空间的探索,在新元古代江南造山带可关注白岗岩型和花岗伟晶岩型铀矿,在扬子陆块与华夏陆块的结合带可重点探索斑岩型铀矿和火山岩型铀矿。以上成果有利于深化对铀、关键矿产区域成矿规律的认识,为今后铀矿勘查、综合找矿和科研工作提供指导与借鉴。

A study of different types of uranium deposits, metallogenic series, metallogenic pedigree and a new prospecting outlook in Hunan Province

On the basis of Geological Records of Central- South Uranium Deposits and Mineral Geology of China of Hunan Uranium Deposits, the authors have summarized the metallogenic regularity of Hunan uranium deposits by systematically collecting the exploration and scientific research on Hunan uranium deposits. The uranium deposits in Hunan Province are divided into three classes, four types and ten sub- types in genetic,three classes: hydrothermal type, marine sedimentary type, and continental sedimentary type. The spatiotemporal distribution of uranium deposits are summarized as following: firstly, the metallogenic geological background and isotopic age indicates that the ore- controlling structures and magmatic, volcanic and hydrothermal activities of rock- controlling basins are concentrated in the Late Cretaceous to Paleogene, with the Late Cretaceous being the main metallogenic period. Secondly, the important uranium deposits are distributed in the periphery of Mesozoic- Cenozoic fault basins. Regional uranium mineralization is restricted by the unique geochemical characteristics of uranium and the unified regional tectonic evolution in a specific period of intracontinental rift stage or regional fault basin stage, reflecting the inherent spatial- temporal unity of uranium regional mineralization. The metallogenic series of uranium- bearing deposits in Hunan Province has been determined and is divided into two metallogenic series assemblages, seven metallogenic series and eight metallogenic sub- series. The consolidation of uranium- bearing metallogenic series in Hengyang basin is an important achievement of this study and is helpful in revealing the inherent space- time unity of uranium regional metallogenesis, analyzing the characteristics of uranium metallogenic evolution, and constructing the uranium metallogenic pedigree. In recent years, comprehensive prospecting for uranium and key minerals has been carried out in key uranium metallogenic areas by applying metallogenic series theory, and important prospecting results have been achieved. Thirteen deposit styles of uranium, such as Jinyinzhai style and Lujing style, have been identified. It is important that while focusing on the hydrothermal medium- large uranium deposits of key uranium metallogenic areas, attention is also paid to the exploration of large- tonnage rock- mass type uranium deposits (porphyry type, alaskite type, granite pegmatite type), as well as to the comprehensive prospecting for key minerals in uranium metallogenic areas and the exploration of the second prospecting space. Alaskite type and granite pegmatite type uranium deposits in the Neoproterozoic Jiangnan orogenic belt should also receive attention. Porphyry type uranium deposits and volcanic type uranium deposits could be extensively explored in the conjunction zone between Yangtze and Cathaysian blocks. The above results are useful in deepening the understanding of the metallogenic regularity of uranium and key mineral resources, and provide guidance and reference for the future uranium exploration, comprehensive prospecting and scientific research.