Trace element signatures of the Carboniferous -Permian deposits in the Bohai Gulf Basin and their facies significance

The present paper deals with the contents of the elements Sr, Ba, Ga, V, Ni and Co, and the ratios of Sr/Ba, Ba/Ga and Ni/Co analyzed by using ICP-MS technique for 42 pieces of the Carboniferous -Permian core samples from four wells in the Bohai Gulf Basin, and gives the following analyses:Sr=(100~200)×10^-6, Ba=(100~700)×10^-6, Ga=(10~40)×10^-6, V=(80~200)×10^-6, Co=(5~30)×10^-6, Ni=(15~45)×10^-6, Sr/Ba=0.2~0.9, Ba/Ga=2~20, Ni/Co=1~4. The results of research show that the marine deposits are developed in the Benxi Formation, the transitional deposits in the Taiyuan Formation, and the continental deposits in the Shanxi Formation and its overlying strata in the Bohai Gulf Basin.