Sea level and low-latitude climate control on sedimentary provenance and paleoenvironmental evolution in the central Okinawa Trough since 19 cal. ka BP

Abstract

This study utilizes AMS ¹⁴C dating, grain size analysis, and elemental composition to ascertain the provenance of sediments in core C01, thereby offering insights into the paleoenvironmental evolution of the Okinawa Trough since 19 cal. ka BP. Between 19.0 and 11.3 cal. ka BP, the sediments were predominantly derived from the Changjiang River, a phenomenon attributed to the river's seaward expansion during periods of low sea level. During this interval, the Kuroshio Current (KC) exhibited relative stability. However, the rise in sea level from 11.3 to 7.3 cal. ka BP resulted in a shift in sediment sources, incorporating contributions from the Changjiang River and/or the continental shelf post-deglaciation to Taiwan, alongside a significant intensification of the KC. This increase in KC intensity is likely correlated with heightened summer insolation in the low latitudes of the Northern Hemisphere and an enhanced East Asian summer monsoon. Additionally, volcanic activity occurring at 7.3 cal. ka BP played a critical role in modifying sediment composition. By 7.3 cal. ka BP, sea levels approximated contemporary conditions, with terrestrial sediments primarily sourced from Taiwan. Around 4.9 cal. ka BP, a marked decrease in KC intensity was observed, potentially influenced by the strengthening of the El Niño-Southern Oscillation, which disrupts subtropical circulation in the North Pacific. The sedimentary records from core C01 illustrate that low-latitude Pacific climate variability since the last deglaciation has significantly impacted changes in sedimentary provenance and environmental conditions in the Okinawa Trough.