Reconstruction of silicate weathering intensity and paleoenvironmental change during the late Quaternary in the Zhuoshui River catchment in Taiwan

Abstract Taiwan Island is one of the best places in the world for the study of earth surface processes during the late Quaternary because of its unique geological, geographic and climatic settings. In this study, we present sedimentary and element geochemical data of Core JRD-S drilled on the Zhuoshui River Delta, aiming to examine the changes of sediment provenance and silicate weathering intensity in response to monsoon climate variability since the last glacial period. Similar rare earth element (REE) compositions between the core sediments and modern Zhuoshui River samples suggest the Zhuoshui watershed was the dominant sediment provenance for the late Quaternary deposition in the river mouth, while the mainland rivers in southeast China including the Changjiang (Yangtze River) could not be the major sediment suppliers. Due to the stable sediment provenance, the geochemical proxy of the core sediments reveals the change of silicate weathering intensity during the late Quaternary in the Zhuoshui watershed was primarily driven by monsoon climate under an active tectonic setting. The weaker monsoonal precipitation in the last glaciation caused weaker erosion (thus less sediment supply) in the mountainous watershed and thus, increased the sediment residence time and silicate weathering intensity. In contrast, the enhanced Holocene monsoonal precipitation might greatly increase the physical erosion and sediment transfer rate from land to sea, which consequently produced more less-weathered sediments. This study provides in-depth insights into sedimentary response to tectonic and monsoon climatic changes during the Quaternary on a tectonically active high-standing island, which increases our better understanding of earth surface processes in the unique continental margin.