Formation Mechanism and Identification Marks of Sequence Boundaries in Continental Fault Depression Basin

A sequence boundary of continental fault depression basin is formed because sedimentary surface is higher than depositional base level or lake basin base level, by which degradation of sediments and non-deposition are resulted. The cease of boundary fault movement , upwarping movement of fault block, uplift of whole lacustrine basin and fall of lake level are the mechanisms of sequence boundary formation. The sequence boundaries have obvious marks on seismic profile, log curves and lithologic character, lithofacies, palaeontologic combination, microelement changes on drilling profile. On the basis of these characters, nine 3rd grade sequences are identified in eogene of Jiyang Depression.