Sediment provenance and weathering in the northern South China Sea and its implications for climate change and sea-level fluctuations over the past 140 kyr

Abstract

Marine sediments contain valuable records of climate change and land-sea interactions. Numerous studies have investigated sediments from the northern South China Sea; however, research on the deep-sea basin southwest of this region remains limited. In this study, we analyze the major and trace elements of sediments collected from the eastern ridge of the Xisha Islands to identify their provenance and examine their responses to climate change over the past 140 kyr. The results indicate that sediments primarily originated from southwestern Taiwan and the Pearl River, with their relative contributions modulated by sea-level fluctuations on glacial-interglacial timescales. During glacial periods, Taiwan Island and the Pearl River contributed approximately 42 % and 58 %, respectively, to the total terrigenous input. During interglacial and intermediate climate periods, their contributions were approximately 52 % and 47 %, respectively. Our findings suggest that the East Asian summer monsoon strongly influenced the chemical weathering of surrounding source regions, although this effect is primarily evident in sediments deposited when the sea level was above −50 m. In contrast, the enhanced weathering intensity observed during glacial periods is attributed to secondary weathering processes at sea levels below −50 m. This study highlights the interplay between sea-level fluctuations, climate change, and chemical weathering processes, offering new insights into the influence of climate change on deep-sea sedimentation.