Qiongdongnan basin has experienced chasmic and depression stages

which can be further divided into 5 substages. Correspondingly

there can be 2 mega sequences (TA

TB)

5 super sequences and 19 sequences. Lowstand system tracts have been developed in every evolutionary stage and are characterized by their multistage and multiplicity. The sedimentary systems of lowstand system tracts include basin floor fan

slope fan

progradational wedge

delta

fan delta

alluvial fan

submarine valley and incised valley. These sedimentary systems are characterized by their time space combination

and can be categorized into isolated type

fault controlled suspension type and coexisting type. Sedimentary systems during chasmic stage are mainly of isolated type

fault controlled suspension type; while those during depression stage are mainly of coexisting type. These lowstand sediments are favorable for the development of source reservoir cap rock combinations

hence there can be various composite traps

such as lithologic

stratigraphic lithologic and structural lithologic traps

which would have large exploration and development potentials.