Sedimentary records of the southern Taiwan Strait since the late Pliocene and implications for sea-level and tectonic changes

Abstract

The Taiwan Strait, connecting the East China Sea to the north and the South China Sea to the south, lies adjacent to the tectonically active Zhe-Min Uplift and the Taiwan Orogenic belt; however, its sedimentary history, such as geochronology, depositional processes, and controlling factors, remains largely unclear. This report presents an integrated study on a 160-m long sediment core (ZK01) retrieved from the southern Taiwan Strait, in terms of magnetostratigraphy, luminescence dating, and sediment grain-size and color. Our findings indicate that the basal age of core ZK01 was ∼4 Ma, with the Quaternary boundary at a depth of 108 m, and the boundary between the lower and middle Pleistocene (0.77 Ma) at 19 m. Prior to 1.07 Ma, the sediment accumulation rate was relatively stable, ranging from 34.4 to 43.3 m/Ma, suggesting a consistent depositional environment. Between 1.07 and 0.77 Ma, the rate increased to 98 m/Ma, likely linked to regional tectonic activity and climate variability during the Mid-Pleistocene Transition (MPT). Constrained by these geochronological results, sediment grain-size and color indices (L*, a*, and b*) were strongly influenced by sea-level fluctuations during the Plio-Pleistocene epoch, while neritic deposits in the southern Taiwan Strait after the MPT were thinner than those in the Yellow and Bohai Seas, likely resulted from local tectonic uplift.