南雄断裂带岩石地球化学特征及其与铀成矿的关系

Geochemical Characteristics of the Nanxiong Fault Zone and their Relationship with Uranium Mineralization

粤北南雄陆相红色盆地及其紧邻的诸广山花岗岩区,是中国重要的花岗岩型铀成矿带。研究表明,南雄断裂带属于伸展体系下的低角度剥离断层,为浅层次的热隆伸展构造,断裂带上部为脆性变形层,下部为韧性变形层,既是导矿构造,又是储矿构造。钻孔岩心揭露表明,断裂带岩石包括构造角砾岩、碎裂岩和糜棱岩。岩石具有显著的碱交代蚀变特征,部分糜棱岩后期遭受构造作用产生破碎,且有基性岩脉穿插。样品地球化学特征分析表明,碱交代和糜棱岩化程度与铀元素的富集有对应关系。这一规律性说明岩石的碱交代和糜棱岩化对铀富集的空间分布有重要作用。

The red basin in Nanxiong north of Guangdong Province and the vicinity of the granite area are the important granite-type uranium mineralization zone. Studies show that the fault zone in Nanxiong is a low-angle normal detachable fault zone of extensional tectonics system, which is also a thermal-uplift extensional structure. The upper layer of the fault zone is brittle deformation, and in the lower layer is ductile deformation. It is a main conductive structures,and also as a host structure. Based on drilling core, the rocks of the fault zone includes breccia, cataclasite and mylonite, which had remarkable characteristics of alkaline metasomatism alteration. Part of mylonite suffer fracturing in the later phase of structures, and in the basic rocks there are some basic vein rocks interluding. Based on the geochemistry analysis of the samples, shows that the grade of uranium have some kind of corresponding relation to alkaline metasomatism and mylonite. This features show that the alkaline metasomatism of rocks and mylonite lithification play an important role on the spatial distribution of uranium enrichment.