Quaternary seismic stratigraphy and paleoenvironments on the continental shelf of the East China Sea

Paleoenvironments and stratigraphy have been interpreted from 4380 km of se ismic profiling collected during a geological and geophysical cruise on the continental shelf of the East China Sea (ECS) undertaken in 1996. The geop hysical data are correlated with a borehole situated on the outer shelf obt ained by Shanghai Marine Geology Bureau, indicating that six seismic units have been preserved since oxygen-isotope stage 6, including four regressive -transgressive cycles. Seismic units U2, U3 + U4 + U5, U6, and U7 are inter preted to correspond respectively to oxygen-isotope stages 1, 3, 5, and 6, implying that sediment partitioning and sequence architecture in the ECS ha ve been controlled by glacio-eustasy and global climate changes. Alternatin g continental and marine strata corresponding to glaciation and interglacia tion are well preserved on the outer shelf of the ECS. Most of the cold env ironment strata, which formed on the outer shelf during oxygen-isotope stag es 2 and 4, are too thin to be recognized on SIG 600J because of resolution , but corresponding erosion surfaces exist. Seismic unit U7 is widespread o ver the shelf, extending to the continental edge and showing little variati on in thickness, as the regression was pronounced and lasted a long time. T hus, U7 can be used as a marker layer for correlation of Quaternary strata on the shelf of the ECS. Post-glacial transgression is obvious in the ECS. Marine strata with varied thickness were developed in the shallow sea of th e inner shelf, thinning toward the outer shelf. The continental shelf of th e ECS has been influenced by Pacific tide-wave systems for a long time, for ming tidal sand-ridge sequences, developed during transgressions, correspon ding to oxygen-isotope stages 7 (or 9), 5, 3 and 1. (C) 2000 Elsevier Scien ce Ltd. All rights reserved.