江西临川地区相山铀矿田构造应力场分析

Analysis of the tectonic stress field in the Xiangshan uranium ore field,Linchuan area,Jiangxi,China

相山铀矿田是中国最大的、与火成岩有关的中低温热液型矿床,断裂构造控矿特征明显。目前该矿床的后备资源出现危机,因此开展矿田构造研究,为深部及其外围找矿提供科学指导迫在眉睫。在野外观测分析和节理、擦痕实地测量的基础上,利用构造解析法、共轭剪节理分析法、断层擦痕反演模拟法及X光岩组法等,通过吴氏网投图分析和计算机的反演计算,确定了相山铀矿田多期次构造活动的变形特征及其主应力方向;并根据构造变形叠加关系及其成岩时代的确定,推断了应力作用的期次和时代。为此,将相山铀矿田的构造应力场划分为3期6个阶段,包括:成矿前的基底变形和早期火山活动阶段,早期矿化蚀变和第一、第二主成矿阶段,及其成矿期后阶段,矿体局部被错断;并深入分析了不同阶段构造活动及其铀成矿特征,探讨了区域构造应力场的演变与铀成矿作用关系,认为两者具有一致性特征,进而指出了区域富大矿体产出的有利构造部位。

The Xiangshan uranium ore-field is the largest volcanic-related meso-epithermal deposit in China and the uranium-mineralization is tightly controlled by fault activities.As exploited and doveloped for many years,the ore-reserve resource of the deposit is in current crisis,although the potential reservoir is probably great.Therefore,the study in ore-field structures is imminent to provide scientific guidance for ore-prospecting in the deep and surrounding areas.This paper mainly presents field measurement results of joints and fault scratches to identify features of tectonic activities and the principal stress direction,using traditional and modern methods in tectonic stress field research.Stages and times of the tectonic stress field are also determined based on successively superimposed deformation relations and diagenesis ages of volcanic rocks.The result showed that the tectonic stress field in the Xiangshan ore field can be divided into three stages and six periods.Basement deformation and two phases of volcanic activities occurred before the metallogensis,and main mineralization stages could be divided into three periods,and uranium ore bodies were locally dislocated by fault activities after the formation of ore-deposits.Characteristics of different phases of tectonic activities and its relationship to the uranium mineralization were additionally discussed,suggesting that the uranium mineralization was consistent with the evolution of the regional tectonic stress field.Favorable structural ore-forming areas for grade-rich ore-bodies in the Xiangshan uranium ore-field were further pointed out.