The diagenetic interplays of organic carbon (OC), sulfur (S), and iron (Fe) in marine sediments and their responses to changes in depositional and climatic conditions are poorly characterized. In this study, chemical speciation and isotopes were combined to characterize diagenesis of OC, S and Fe in sediments of the middle Okinawa Trough (OT), a back-arc deep basin along the edge of the East China Sea outer shelf, since the Last Glacial Maximum (LGM). Two key geochemical proxies, i.e., OC/pyrite-S ratios and the degrees of pyritization, indicate anoxic bottom-water conditions during the last Glacial/Deglacial, which promoted burial of OC and pyrite. However, a shift to oxic conditions during the Deglacial-Holocene transition facilitated aerobic respiration, resulting in lower burial of OC and pyrite. In contrast to previous studies, the environmental changes induced by large sea-level rises since the LGM have not triggered significant variations in pyrite-S isotopic compositions, probably due to persistently low sedimentation rates. Variable extents of Fe enrichment are identified in the sediments since the LGM, with lower enrichment during the Holocene probably due to increased distance of Fe shuttling and concomitant Fe ageing. Anoxic bottom water during the Glacial/Deglacial did not induce an expected intensification of OC sulfurization, probably because sedimentary Fe enrichment favored pyrite formation but competitively dampened OC sulfurization. Lines of geochemical evidence hint at a discontinuous deposition at ~200 cm depth probably caused by mass wasting.

海洋沉积物中有机碳（OC），硫（S）和铁（Fe）的成岩作用及其对沉积和气候条件变化的响应的特征很差。在这项研究中，结合了化学形态和同位素，以表征冲绳海槽中部沉积物中的OC，S和Fe的成岩作用，该冲绳海槽是自上一次海啸以来沿东海外陆架边缘的弧后深盆。冰川最大值（LGM）。OC /黄铁矿-S比率和黄铁矿化程度这两个关键的地球化学指标表明，在最后一次冰期/冰河期中，缺氧的底水条件促进了OC和黄铁矿的埋葬。但是，在向冰期-全新世过渡期间转变为有氧条件有利于有氧呼吸，从而降低了OC和黄铁矿的埋葬。与以前的研究相比，由于LGM尚未引起黄铁矿-S同位素组成的显着变化，这可能是由于持续低的沉积速率所致，海平面上升引起的环境变化。自LGM以来，沉积物中铁的​​富集程度有所不同，在全新世期间富集程度较低，这可能是由于Fe穿梭距离的增加和伴随着的Fe老化。冰川期/冰川期的缺氧底部水并未引起预期的OC硫化强化，这可能是因为沉积铁富集有利于黄铁矿形成，但竞争性地抑制了OC硫化。地球化学证据线暗示可能是由于质量浪费造成的〜200 cm深度的不连续沉积。