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火山岩型铀矿床通常与酸性至中性的火山岩类有关 ,而 6 710铀矿区的铀矿化与双峰式火山岩和基底花岗岩有紧密的空间关系。研究表明该套双峰式火山岩中玄武岩的Rb Sr等时线年龄为173± 9 7Ma ,流纹岩为 16 4 8± 0 57Ma。前者的不相容元素地球化学特征与板内拉斑玄武岩相一致 ;后者为准铝质 (ACNK =0 88- 0 96 ) ,稀土元素 (ΣREE :(2 50 33- 2 95 99)× 10 - 6 )和高场强元素 (Y ,Zr,Nb等 )的含量较高 ,与A型花岗岩的地球化学特征相似。基底花岗岩的Rb Sr等时线年龄为 2 4 9 9± 5 5Ma ,岩石为过铝质 (ANKC =1 18- 1 2 6 ) ,富集LREE((La/Lu) N=2 8 51-55 0 9)和大离子亲石元素 (Rb ,Th ,U等 ) ,与同造山S型花岗岩的地球化学特征一致。双峰式火山岩表明该区在燕山早期具有拉张裂解的地球动力学背景 ,基底花岗岩代表了海西晚期的挤压造山环境。它们分别为本区铀成矿提供了矿化剂 (CO2 - 3)和铀源。
Volcanic-type uranium deposits are usually associated with acidic to neutral volcanic rocks, while uranium mineralization at 6 710 has close spatial relationships with bimodal and basement granites. The study shows that the Rb Sr isochron age of the basalts in the set of bimodal volcanic rocks is 173 ± 9 7Ma and that of rhyolite is 16 4 ± 0 57Ma. The former incompatible element geochemical characteristics are consistent with intraplate pullout basalt; the latter are quasi-aluminum (ACNK = 0 88- 0 96), rare earth elements (ΣREE: (2 50 33- 2 95 99) × 10 - 6) and high field strength elements (Y, Zr, Nb, etc.) are high, similar to the geochemical characteristics of A-type granites. The Rb Sr isochron age of the basement granites is 2 499 ± 5 5Ma and the rocks are of permaluminous (ANKC = 18-126), enriched in LREE ((La / Lu) N = 2 8 51-55 0 9) and large ion lithophile elements (Rb, Th, U, etc.) are consistent with the geochemical characteristics of the Tongsheng S-type granites. The bimodal volcanic rocks show that the area has a tectonic background of extensional cracking in the early Yanshanian. The basement granite represents the Late Hercynian crust orogeny. They provide mineralization agent (CO2 - 3) and uranium source for uranium mineralization in this area respectively.