Zhao Junqing, Ji Youliang, Zhang Shanwen. APPLICATION OF GEOCHEMICAL METHODS IN THE RECOGNITION OF HIGH-RESOLUTION SEQUENCE BOUNDARY[J]. 2003, 24(3): 264-268.DOI: 10.11743/ogg20030314.
Clay minerals and trace elements are widely distributed in the different types of sediments
which are so sensitive to environment change.The characteristics of clay minerals (sedimentary differentiation
mineral assemblages
and mineral composition and contents) has provided the information of environment change during their formation process.After studying the typical lithogeochemical parameters of high-resolution sequence units in the 3rd and 4th of Shahejie Fm in the fall-wall of Shengbei fault
Dongying depression
it has been found that mineral composition (including clay minerals and cements)
chemical constituents (trace elements) would be periodically changed with the pace of change cycle of lake surface controlled by paleoclimate.The contents of illite + mixing-stratified illite/semectite and kaolinite +chlorite as well as paleosalinity show distinct change features above and below high-resolution sequences boundary.In the water transgressive system
the content of kaolinite is increased but the content of semectite and value of paleosalinity are gradually reduced from bottom to top.However these characteristics in water regressive system would be opposite. On the sequence boundary under different transgressive and regressive water systems
the contents of dolomitic cement is relatively high
while the contents of calcitic and mixing cements is relatively low.