Sedimentary history of the coastal plain of the south Yellow Sea since 5.1 Ma constrained by high-resolution magnetostratigraphy of onshore borehole core GZK01

Abstract

The thick sedimentary sequences of the East Asian continental shelves are archives of information on tectonics, sea-level fluctuations, flood plain evolution, and changes in the East Asian monsoon climate. However, long sedimentary sequences with a reliable chronological framework from this setting are scarce. Here, we present an integration of lithostratigraphic, rock magnetic, and magnetostratigraphic results for the sedimentary sequence of a 285.0 m core (GZK01) recovered from the northern Jiangsu coastal plain of the onshore South Yellow Sea, eastern China. Alluvial, fluvial, lacustrine, and marine deposits were identified according to lithofacies analysis, and detrital magnetite and hematite are the main magnetic carriers. The magnetostratigraphic results show that core GZK01 records the Brunhes, Matuyama, Gauss, and Gilbert chrons, and has an extrapolated basal age of ∼5.1 Ma. This record is the oldest sedimentary sequence yet reported from the continental shelf of the South Yellow Sea. Integrating the geochronological framework with changes in lithofacies, a conceptual model of the environmental evolution of the northern Jiangsu coastal plain is proposed. For a long interval during the Pliocene, the drilling area was a lacustrine environment. From the Late Pliocene to the Early Pleistocene, the disappearance of the paleolake and a transition to a fluvial and marine environment suggests the peneplanation of the northern Jiangsu coastal plain. Cumulative land-sea interactions since 0.8 Ma subsequently shaped the modern geomorphology. The observed process of sedimentary evolution was possibly controlled by regional tectonics and long-term climate changes.