相山铀矿田成矿古水文地质分析

相山矿田是我国著名的大型热液铀矿田。该矿田产于中生代相山火山岩盆地古水热系统之中，是水热系统中水－岩相互作用的产物。因此，查明当时的古水文地质条件对于研究矿床成因、指导找矿具有重要意义。本文根据相山地区的地质基础资料、构造演化历史和古气候条件，运用构造－古水文地质分析法，对该矿田进行了古水文地质分期、分区，分析了古地下水的补给区、排泄区和径流途径，并对成矿古水热系统的形成条件进行了探讨。

ANALYSIS OF PALEOHYDROGEOLOGY FOR THE MINERALIZATION IN XIANGSHAN URANIUM ORE-FIELD

Xiangshan uranium ore-field is a famous hydrothermal uranium ore-field.It occurs in the fossil hydrothermal systems within Xiangshan Mesozoic volcanic basin and is the product of water-rock interactions in the hydrothermal systems.Therefore,the reconstruction of the paleohydrogeological setting is of great importance to genetical study of the mineralizations and to the prospecting for the deposits.Based on field geology,tectonic evolution history and paleo-climate condition,after the paleohydrogeological stages and zonation were defined in this paper,the recharse,discharge zones and movement of the paleo-groundwater were analyzed,and then the formation condition of the hydrothermal systems was discussed.Two ore-forming hydrothermal systems in Xiangshan ore-field have been recognized by means of tectonopaleohydrogeological analysis.One is the north hydrothermal system which produced the sodium-metasomatic take uranium deposits,and the other is the west hydrothermal system which yielded the fiuorite-hydromica type uranium deposits.According to hydrogen and oxygen stable isotope studies,fluids of the hydrothermal systems are considered to have been derived mainly from meteoric water.Modeling of the paleogethermal field shows that the heat for Xiangshan hydrothermal system was denyed mainly by ground water circulation to deep levels in a relatively higher geothermal gradient.