Structural evolution of two‐stage rifting in the northern East China Sea Shelf Basin

Abstract

This study focuses on the stratigraphic correlation and structural evolution of the Ieodo and Jeju basins in the northern East China Sea Shelf Basin (ECSSB), which are compared to the Changjiang and Xihu depressions, respectively. Based on multi‐channel seismic reflection data, Cenozoic sedimentary successions resting on the acoustic basement in both basins can be divided into multiple syn‐ and post‐rift units. Basement‐involved structures exhibit different orientations, that is, E–W (ENE–WSW) and NE–SW trending structures in the Ieodo and Jeju basins, respectively. They represent the development of two‐stage rifting. The first rift stage began in the Palaeocene and was only restricted to the Ieodo Basin located west of the Hupijiao Rise. The second rift stage subsequently occurred in the Jeju Basin located east of the Hupijiao Rise during the late Eocene to Miocene. The Eocene post‐rift unit of the Ieodo Basin was uplifted while the Jeju Basin was subsided by bounding faults. The sequential development of rift structures in the basins suggests eastward migration of the Cenozoic rifting in the northern ECSSB. The NE‐trending rift structure of the Jeju Basin parallel to the subduction zone of the Pacific Plate suggests that the second rift stage possibly evolved under the influence of the back‐arc extensional regime. The Hupijiao Rise between the Ieodo and Jeju basins was possibly a geologic basement in the Palaeocene and was an uplifted remnant caused by footwall exhumation during the second rift stage of the Jeju Basin.

Improvement of fault interpretation with seismic attribute analysis of Jeju Basin, offshore southern Korea, East China Sea

“…Two phases of rifting have affected the tectonic evolution of the East China Sea Shelf Basin from the Late Cretaceous to Miocene (Lee et al, 2006;Shang et al, 2017;Lee et al, 2018). In the initial rifting phase, graben and/or half-graben structures were formed by the NW-SE extension in the Late Cretaceous to Early Eocene (Jilong movement) (Lee et al, 2006;Ye et al, 2007;Cukur et al, 2011).…”

“…The western depression of the basin experienced regional uplift during the Late Eocene to Early Oligocene (Yuquan movement) (Cukur et al, 2011;Zhang et al, 2016). During early Oligocene, the basin experienced a second rifting phase, which turned into a post-rifting phase after the Miocene uplift (Zhang et al, 2016;Lee et al, 2018). During the midlate Miocene, when the Pacific Plate subducted to the west, a thrust fold formed at the eastern and southeastern part of the continental shelf of the East China Sea, named the Longjing movement (Zhou et al, 1989;Yang, 1992).…”

“…The main rift stage occurred from Paleocene to Eocene, forming graben and half-graben structures. The seismic units bounded by the mega-sequence boundaries reflect depositional sequences that formed during tectonically controlled basin development (Lee et al, 2006;Cukur et al, 2011;Lee et al, 2018).…”