Abstract: Clay minerals and trace elements are universally distributed in various deposits and sedimentary rocks. They are extremely sensitiveto environmental changes. And the characteristics of their sedimentary differentiation and combination as well as mineral composition and con-tents have recorded the changes of various environmental factors when they formed. It is of an important indicating significance to reconstructpaleo-env ironment and to study continental lake basin's varied water depth. Taking each sequential element of the third member and the fourthupper member of Shahejie formation in Sengbei fault' 's downthrow, Dongy ing sag as an example, the lithologic geochemical ty pomorphic parame-ters are studied. It is suggested that in cyclic lake-level changes controlled by paleo-climate, cyclic changes could occur in mineral composition(clay minerals and cements), chemical composition (trace element), etc., in sedimentary rocks.

Key words: clay mineral, trace element, cement, paleo-salinity, sequence, Dongying sag