| Abstract: | With a comprehensive geological and geophysical data base,the Paleogene in the Liaodong Bay area,which consists of the Kongdian,Shahejie and Donghying Formations from the base to top,was divided into 4 second-order sequences and 8 third-order sequences based on the characteristics of the se-quence boundaries. Each third-order sequence is subdivided into the lowstand,lake transgressive and highstand systems tracts. The Lowstand systems tract (LST) is mainly composed of progradational parasequence sets,while the lake transgressive systems tract (TST) largely consists of the retrograda-tional parasequence sets and the highstand systems tract (HST) is dominated by the progradational parasequence sets. The main types of depositional systems include the shallow lake,semi-deep lake,deep lake,delta,fan delta,braided fluvial delta and nearshore subaqueous fan. The braided fluvial delta and fan delta depositional systems are mainly confined to the sequences of the lower SEs4-Ek,SEs3 and SEs1 2,while the sequences of SEd3,SEd2 and SEd1 are dominated by the delta and nearshore subaqueous fan depositional systems with the latter being developed at the downthrown side of the basin-bounding fault in each sequence. The evolution of the depositional systems is always con-trolled by the paleo-tectonic setting and the ancient landform in the space and geological time. It is concluded that the most favorable reservoirs are distributed in the Liaoxi low uplift and the central Liaozhong sag. |
