Seismic sedimentology of sub-clinoformal shallow-water meandering river delta: A case from the Suning area of Raoyang sag in Jizhong depression, Bohai Bay Basin, NE China

Abstract

The seismic sedimentology characteristics of sub-clinoformal shallow-water meandering river delta can be comprehensively analyzed by core, well logging and 3-D seismic data. This paper summarizes the sedimentary pattern of sub-clinoformal shallow-water meandering river delta of Suning area in Raoyang sag, Jizhong depression of Bohai Bay Basin. In Suning area, there are eight fourth-order sequences recognized from the upper part of Sha 1 Member (Es1s) to Dong 3 Member (Ed3), reflecting periodical change of lake level. From the central lake to the shore, and from the transgressive to highstand systems tracts, the color of mudstones varies from grey to red, showing a drop of lake-level. The seismic reflection pattern indicates the drop of lake level: the shingled reflections in Es1s (SQ?3) indicate water depth of 40−60 m in the lake center, followed by sub-parallel (SQ?4-SQ?6) with lower continuity reflections, and disappearance of shingled reflections, showing water depth no more than 30 m. Analysis of core, well logging, and seismic amplitude strata slices reveal that the sequences SQ?4-SQ?6 of Es1s are sub-clinoformal shallow-water meandering river delta, different from the shingled reflection shallow-water meandering river delta in SQV3 of Es1s. The main seismic sedimentology characteristics are channel forms and lobate landforms advancing to the central lake by multiple zones, indicating numerous distributary channel and deltaic lobes depositions. Key words: shallow-water meandering river delta, sub-clinoformal seismic reflection, seismic sedimentology, Raoyang sag, Bohai Bay Basin