Paleostress regime evolution in South China induced by dynamic changes in Izanagi-Pacific subduction since the Cretaceous

Abstract

A complex intraplate deformation sequence since the Cretaceous is recorded in the basin–mountain belt along the South China continental margin and provides a critical window to reconstruct the paleostress regime since the Cretaceous and further explore the relationship between the intraplate deformation episodes in South China and the dynamic changes in Izanagi-Pacific subduction. Here, integrating the clues from the field investigation, fault-slip inversion, and zircon U–Pb chronology in four regions along the basin–mountain belt reveals six paleostress regimes on the South China margin, listed in order of decreasing age: E‒W extension (ca. 145-120 Ma), NW‒SE extension (ca. 120-105 Ma), NW‒SE compression (ca. 105-100 Ma), N–S extension (ca. 100-65 Ma), NE‒SW compression (ca. 65-55 Ma), and NE‒SW extension (ca. < 55 Ma). The four extensional regimes controlled regional subsidence and sedimentation, resulting in NW-striking and E–W-striking alignments of Early and Late Cretaceous basins, respectively. In comparison, the two compressional regimes produced two regional unconformities between the Early and Late Cretaceous strata and between the Late Cretaceous and Paleogene strata. Our results suggest that the prevailing Cretaceous extension in South China likely started at ca. 145 Ma, reversed due to short-term compression, and restarted at ca. 100 Ma. By comparing the history of the Izanagi-Pacific plate subduction, we conclude that the dynamic changes in the subduction process have been the primary force driving intraplate deformation in South China since the Cretaceous.