邹家山铀矿床含矿裂隙系统研究

Study on the ore-bearing fracture system of the Zoujiashan uranium deposit,Jiangxi,SE China

邹家山铀矿床位于相山铀矿田西部,是相山铀矿田最重要的矿床,该矿床属于受断裂裂隙构造控制的脉状中-低温热液矿床,以规模大、品位高而著称。对邹家山铀矿床露天采场含矿构造的详细调查显示,含矿裂隙系统由许多弧形小断层及其所夹持的透镜状岩块构成;含矿裂隙主要为北北东向和北北西向,次为其他方向;含矿裂隙是由"X"剪节理基础上发展起来的,经过持续变形而形成;矿液充填交代时NNE向断裂具有一定的左行特点,近南北向裂隙往往是矿脉膨胀部位;成矿流体压力比较大,具有明显的水压致裂作用,形成同一露头上多个方向弧形和不规则铀矿脉,并且有从高一级裂隙向低级别裂隙、微裂隙边矿化边扩展的特点。邹家山铀矿床矿带(矿体群)呈斜列状分布,平面上呈左列式,单体北东走向,轴线北东东走向;剖面上单体中-陡倾角,轴线中-低倾角倾向西。矿带(矿体群)的空间分布与邹家山-石洞断裂带明显不一致,反映出矿带可能受一组走向北东东(50°~65°)、中-缓倾角(30°~45°)倾向北西的隐性构造控制,而不是受陡倾角的北东向邹家山-石洞断裂带控制。就邹家山铀矿区而言,进一步找矿方向在现有矿带的南西西方向深部。

The Zoujiashan uranium deposit is located in Le’an county, Jiangxi Province, in the western area of the Xiangshan uranium ore field. It belongs to low-mesothermal lode deposit controlled by fractures and famous for its large scale and high uranium grade. Upon a thorough investigation of the ore-bearing structure in the open pit mining of the Zoujiashan uranium deposit, the authors consider that the ore-bearing fracture system of the Zoujiashan uranium deposit is composed of several arcuate fault and lenticular rocks surrounding the arcuate fault. The ore-bearing fracture, trending mainly along north-east-north and north-west-north and partly other direction, is based on X-type shear joint and characterized by continued progressive deformation. Ore veins often occur along north-south trending facture indicating that the NNE-trending ore-bearing fault occurred as a left-slip movement while the mineralizing fluid entered the fault, resulting in infilling and metasomatism. The arcuate and irregular uranium ore veins in different directions indicated the higher pressure of mineralizing fluid with hydraulic fracturing to the rocks. In fact, the ore-bearing fractures propagate from high degree to lower degree or micro once while mineralization occurs at high fluid pressure. The ore-belts(or ore body groups) are arranged obliquely in the Zoujiashan uranium deposit. In other words, the single ore-belt(or ore body groups) is NE-trending and the ore-belts are arranged along a NEE-trending axial line on the plane;while, the single ore-belt(or ore body groups) is dipping to NW at middle-high angle and the ore-belts are arranged along an axial line with low-middle angle dipping to NW on the section. Thus, the ore-belts(or ore body groups) maybe controlled by a high degree hidden fault with NEE-trending(50~65) and at low-middle angle(30~45) dipping to northwest, but not by the Zoujiashan-Shidong fault with NE-trending and at high angle dipping to northwest. We propose that the further prospecting in the Zoujiashan uranium deposit should be in the south-west-western area of present ore belts.