A new discovery of source contribution and transport mechanism of clay minerals in Taiwan Canyon-Manila Trench

Abstract

The northeastern South China Sea is characterized by a complex system of submarine canyons, making the study of its sediment “source-to-sink” processes crucial for understanding regional tectonic-climate interactions. This study focuses on two areas: the Taiwan Canyon and northern Manila Trench in the northeastern South China Sea. We used X-ray diffraction to analyze clay minerals. The analysis examined surface and core sediments from seven sampling sites. We studied both composition and sources of these minerals. We quantified the contribution rates from different sources and detailed the transport pathways. The results indicate that clay minerals in the study area are predominantly composed of illite (58.9 %–70.7 %) and chlorite (22.2 %–39.6 %), while smectite (0.3 %–7.4 %) and kaolinite (0.3 %–12.2 %) are present in significantly lower abundances. Taiwan Island is the primary source of clay minerals (47.9–97.7 %), transported to the northern Manila Trench via the Penghu-Gaoping Canyon system and deep-water currents. Luzon Island contributes minimally (<7.4 %), with its materials carried by the Kuroshio Current. The Pearl River catchment serves as a secondary source (1.5–48.2 %). This study proposes that Pearl River sediments in the northern South China Sea are transported via two distinct pathways: (1) shelf sediments are transported through the Taiwan Canyon to the northern Manila Trench, while (2) slope sediments are delivered directly to both the mid-Taiwan Canyon (ZC4) and the northern Manila Trench (YF6). These results offer significant scientific insights into the “source-to-sink” sedimentary processes along the continental margin of the northeastern South China Sea.