Sources and burial of organic carbon in the middle Okinawa Trough during late Quaternary paleoenvironmental change

• Published in: Deep-sea research. Part I, Oceanographic research papers Oceanographic research papers, 2016-12, Vol.118, p.46-56
• Main Authors: Shao, Hebin, Yang, Shouye, Cai, Feng, Li, Chao, Liang, Jie, Li, Qing, Hyun, Sangmin, Kao, Shuh-Ji, Dou, Yanguang, Hu, Bangqi, Dong, Gang, Wang, Feng
• Format: Article
• Language: English
• Subjects: Carbon; Deep sea; Grain size; Late Quaternary; Marine; Ocean currents; Okinawa Trough; Organic carbon; Paleoenvironment; Productivity; Scientific papers; Sea level; Sediment; Sediments
• ISSN: 0967-0637; 1879-0119
• DOI: 10.1016/j.dsr.2016.10.005

The sediments from a piston core ECS12A recovered from the middle Okinawa Trough in the East China Sea were measured for total organic carbon (TOC), total nitrogen (TN), and other biogenic elements to provide constraints on the sources and burial rates of depositional organic matter (OM) and on the changes in primary productivity since 19 ka. The last glacial sediments (ca. 17–19ka) are characterized by low contents of biogenic elements and well-developed turbidite layers, suggesting low primary productivity but a high component of terrigenous sediment. With rising sea level and enhanced monsoons during the deglacial period, the proportion of marine OM gradually increased. The least negative δ13Corg values and the smallest grain size of sediments deposited ca. 10–14.5ka indicate high primary productivity and a sedimentary environment dominated by the marine component. The source and burial rates of OM in the Holocene sediments (ca. 5.4–10ka) were largely controlled by the intensification of the Kuroshio Current, which caused a slight decrease in primary productivity, but strengthened the oceanic circulation in the East China Sea. Overall, the source-to-sink process of OM in the Okinawa Trough is governed by complex interactions between sea level, climate and ocean circulation. •Organic carbon isotope is more reliable than TOC/TN in tracing the sources of organic matter.•Terrigenous and marine organic matter contributions changed since the last glacial period.•Turbidites affect the sources and burial of sedimentary organic matter in low sea-level stage.•Paleoenvironments constrain the sources and burial of depositional organic matter.