Chronostratigraphic framework of the East China Sea since MIS 6 from geomagnetic paleointensity and environmental magnetic records

Continental shelf is a globally important reservoir for terrigenous sediments, and provides sediment transportation pathways that extend from the shoreline to abyssal basins. Due to the strong land-sea interaction in response to frequent sea level change during the late Quaternary and methods' constraint, it is a big challenge to establish a reliable chronostratigraphy on the continental margin with terrigenous sediments dominance. Relative geomagnetic paleointensity (RPI) is quite useful for high-resolution chronostratigraphy in Brunhes epoch. In this study, relative paleointensity record for a sediment core (SFK-1, 82.9 m) from the outer East China Sea (ECS) shelf was studied. Rock magnetic results show that coarse vortex state magnetite is the dominant magnetic carrier throughout the core and that these sediments generally meet the accepted criteria for constructing relative paleointensity (RPI) record. RPI was established by normalizing the natural remanent magnetization (NRM) with isothermal remanent magnetization (IRM), both after 30 mT alternating demagnetization. Further, our RPI record was correlated with PISO-1500 and 7 age tie points were obtained. An age model is established for SFK-1 core with a basal age of 165 ka by combining the radiocarbon dates, relative geomagnetic paleointensity, and tandem correlation of environmental magnetic parameters to foraminiferal stable oxygen isotopes, which provides a reliable chronological framework for the later paleoenvironmental studies of ECS. The consistency of RPI record of SFK-1 and other worldwide observations suggest that global-scale pattern of geomagnetic paleointensity behavior is also documented in the sediments of the East China Sea, and the RPI of SFK-1 can be used as a reference curve for the RPI studies of other cores of ECS area, and even the whole west Pacific margin seas.