桂北摩天岭拉培地区铀矿化元素地球化学特征

Element Geochemical Characteristics of Uranium Mineralization in Lapei Area,Motianling,Northern Guangxi

拉培地区位于摩天岭岩体东部,具有较为优越的铀成矿地质条件。从S-O同位素、微量元素和稀土元素地球化学等方面,重点分析了拉培地区EW向含矿构造的成矿流体来源和地球化学特征。研究结果表明:拉培地区F_(6)断裂构造与F_(w)断裂具有相似的S-O同位素特征,δ^(18)O_(样品-SMOW)值为4.9‰~13.7‰,δ^(18)O_(水-SMOW)值为-7.00‰~-0.35‰,δ^(34)S值为-2.45‰~7.01‰,与达亮矿床内带(δ^(34)S值为-3.5‰~9.1‰)和新村矿床(δ^(34)S值为-5.6‰~8.4‰)类似;F_(6)断裂构造岩富集As、Sb、Hg、Cu、Pb、W、Co、Be等,尤其以As、Sb、Hg等前缘晕元素更为富集,这些成矿指示元素与U相关性较高,铀成矿作用强烈且延伸性较好,具有深源特征;另外从Y/Ho值大于围岩两方面同样验证了F_(6)断裂具有深源特征。从含矿构造、成矿物质、成矿热液、元素地球化学特征、蚀变、成矿标高等方面与新村矿床进行了对比讨论,认为二者具有相类似的铀成矿条件。综合认为拉培地区近EW向构造具有较好的找矿潜力,尤其是深部。

Lapei area is located in the east of the Motianling rock mass, which has superior geological conditions for uranium mineralization. The ore-forming fluid sources and geochemical characteristics of EW-trending ore-bearing structures in Lapei area are studied by S-O isotopes, trace elements and rare earth element geochemistry analyses.The results show that the F_(6) structure in the Lapei area has similar S-O isotope characteristics with F_(w).The δ^(18)O_(sample-SMOW )value is 4.9‰~13.7‰, the δ^(18)O_(water-SMOW )value is-7.00‰~-0.35‰, and the δ^(34)S value is-2.45‰~ 7.01‰, which is similar to the Daliang deposit(δ^(34)S value is-3.5‰~9.1‰) and the Xincun deposit( δ^(34)S value is-5.6‰~8.4‰). F_(6) tectonite is rich in As, Sb, Hg, Cu, Pb, W,Co, Be, etc, especially the front halo elements such as As, Sb, Hg are more enriched.These ore-forming indicator elements have a high correlation with U, and uranium mineralization is strong and deep.It is also verified that F6 has deep source characteristics from two aspects that the Y/Ho value is greater than the surrounding rock. The ore-bearing structure, ore-forming material, ore-forming hydrothermal fluid, element geochemical characteristics, alteration and metallogenic elevation are compared with the Xincun deposit. It is considered that the two deposits have similar uranium metallogenic conditions. It is considered that the near EW structure in Lapei area has good prospecting potential, especially in the deep part.