Abstract:

Certain properties of sedimentary rocks are a function of the depths of waterbody in shallow water environment.However they are not sensitive to the variation of the depth of waterbody in deep water environment. It is still a weak point in sequence stratigraphy to recognize the sedimentary cycles of lacustrine strata formed in deep water environment．Well Niu 38 with fairly full data，located in the Niuzhuang region，Dongying depression，is chosen to study in this paper．Some indexes sensitive to the variations of the depth of water，such as TOC，acoustic time，REE，etc., combined with Fisher plot，are used to recognize the sequences and system tracts of deep water envimnment，and good results have been obtained．As shown in thisnpaper，low contents of TOC and REE，together with the variation of the slopes of acoustic time curves and  Fisher plot，appear on the boundaries of sequences and system tracts．

Key words: deep water environment, sequence, system tract, sensitive index