Abstract:

Volcanicity was violent during the Early Carboniferous in Santanghu region.The volcanic rocks consist of basalts,andesites and dacite liparite,with andesites playing the main part.Geochemical analysis indicates that the basalts are characterized by high content of Al₂O₃,low contents of FeO+0.9Fe₂O₃ and TiO₂,rich macroion lithophile element(LIL)and LREE.The spider diagram of trace element ratio and the REE distribution patterns show the characteristics of the island arc calc alkaline series.In addition,basalt discrimination diagrams,such as Nb-Zr-Y and Cr-Ce/Sr,suggest that Santanghu area was in an island arc envirnment during the Early Carboniferous.