Geochemical characteristics and genesis of Mesozoic acid dikes in Miaoershan area

There are two types of Mesozoic acid dikes in Miaoershan area, granite-porphyry and fine-grained muscovite granite. The acid dikes are characterized with relatively higher content of Al2O3, K2O, Na2O, slightly lower content of TiO2, MgO, the enrichment of Rb, Th, U and Ta, depletion of Ba, Sr in trace elements, relatively low total REEs and enrichment in LREE with strong Eu depletion. In the CaO/Na2O-Al2O3/TiO2 and Rb/Sr-Rb/Ba diagram, the Mesozoic acid dikes belong to crust sourced type granite which is similar to Douzhashan granite and Xiangcaoping granite. The study result suggests that the acid dikes and granite come from the same deep sources and formed by the raising melt part along the fault and the contact zone. The intense crystallization and differentiation may cause the enrichment of uranium in the residual melt and provide material source for uranium mineralization. (authors)