Abstract:

The acceleration and decelaration in the episodic subsiding process (nonlinear tectonic subsidence) of the basement of faulted lacustrine basin have distinct controlling effect on the formation of sequence, and could strenghthen or weaken the information of sequence boundary, result in the advance or delay of system tract. Type Ⅱ sequence interface was formed when the basement nonlinear subsidence speeded up and the tectonic subsidence acceleration was bigger than or equal to lake level falling acceleration. The coupling between basement nonlinear subsidence and lake level elevation and subsidence has strong control over fluviation manner and the deposit distribution. According to this and applying sandbody isopach map, the correctness of sequence division could be verified. The characteristics could also be used as the evidence in sequence recognition.

Key words: faulted lacustrine basin, nonlinear subsidence, type Ⅱ seguence, Nanpu Depression