The K-bentonite which contains abundant geochemical information is widely distributed in Wufeng Formation and Longmaxi Formation in Sichuan Basin and its peripheral areas. In order to make a further study of the geological significance of the K-bentonite in black shale，we have learned the K-bentonite by the methods of XRD，XRF，ICP-MS and combined with the outcrop observation. Researches show that the bentonite in the study area mainly composed of illite，plagioclase，quartz and other mineral composition. The main elements mainly composed of SiO2，Al2O3，Fe2O3，K2O and the K2O/Na2O is 15.54～270. The trace elements are rich in Th，U，Pb，Zr，Hf，Ta and Rb，Cs，Ba，and deplete in La，Ce，Sr，Sm，Eu. The ∑REE is 19.58×10-6～383.88×10-6，average is 105.43×10-6 ；LREE/ HREE is 0.74～12.67，average is 3.93；and rich in LREE，deplete in HREE. The Light and heavy rare earth elements differentiation is obvious，Eu negative abnormity，and there is no evidently Ce abnormity. Comprehensive analysis suggests that：1） The bentonites in Wufeng Formation and Longmaxi Formation in Sichuan Basin and its peripheral areas have the characteristics of high potassium low sodium，and coincide with the K-bentonite. The bentonites have similar characteristics with the same material sources. 2） The tectonic environment of original rock mainly is the island arc environment，also exists certain intraplate environment，volcanic ash may mainly come from the North Qinling Mountains. 3） Volcanic ashes can improve the ocean surface primary productivity and provide material basis for the high quality shale.
Lu Bin Qiu Zhen Zhou Jie Dong Dazhong Wang Hongyan Xue Huaqing Zhou Shangwen. The characteristics and geological significance of the K-bentonite in Wufeng Formation and Longmaxi Formation in Sichuan Basin and its peripheral areas[J]. Chinese Journal of Geology, 2017, 52(1): 186-202.