Late Cretaceous-Paleogene rift initiation of the southwestern East China Sea Basin: Implications from a fission-track study of the Changle-Nan'ao Belt

The East China Sea Basin is an ideal area for studying the subduction processes linked with this section of the active West Pacific continental margin. The initial rift time associated with the opening of the East China Sea Basin remains strongly controversial. This paper provides a perspective based on the apatite and zircon fissiontrack analyses of the Changle-Nan'ao Belt, located on the coastal mainland of eastern China. The results reveal a period of rapid exhumation of this belt, trending from 86 Ma in the north to -66 Ma in the south. From -66 Ma until the present exhumation was very slow. The data and their thermal history modeling results imply that the initial rift time of the East China Sea Basin most likely occurred at 80-70 Ma. The younging trend observed from the north to the south of the study area continues along the coastal margin to the northwestern margin of the South China Sea. This suggests the presence of a diachronous rift opening from the southwestern East China Sea during the Late Cretaceous southwards, and to the northwestern South China Sea during the Late Cretaceous-Paleogene. The rapid exhumation is coincident with the rapid decrease in plate velocity of the Izanagi Plate, Pacific Plate, and Neo-Tethyan and Indian Plate during the Late Cretaceous-Paleogene.

Automated summary

This paper presents a new perspective on the initial rift time of the East China Sea Basin based on the analysis of the apatite and zircon fission track data from the Changle-Nan'ao Belt. The study suggests that the rift opening most likely occurred at 80-70 Ma and reveals a diachronous rift opening from the southwestern East China Sea to the northwestern South China Sea during the Late Cretaceous-Paleogene.