Enhanced deepwater circulation and shift of sedimentary organic matter oxidation pathway in the Okinawa Trough since the Holocene

Abstract

High‐resolution biogeochemical and magnetic property analyses of a 20‐kyr sediment core in the Okinawa Trough revealed a significant upward decrease in total sulfur content (TS) at around 10 cal ka BP, which coincides with a transformation from foliation to anomalous sedimentary magnetic fabric, which indicates an enhancement of deepwater circulation. Synchronous change in biogeochemical and magnetic properties in sediments was likely triggered by the intensified Kuroshio Current, which strengthened surface water productivity and the relative input of marine organics to the sediments. However, this event did not promote sedimentary sulfur burial; instead, the synchronously enhanced deepwater circulation switched the organic carbon oxidation pathway from sulfate reduction to aerobic respiration which resulted in TS‐depleted sediments.