Geochemistry of carbon at DSDP Legs 56-57 Holes@en

Forty-three core sections from Sites 434, 435, 438, 439, and 440 on the landward side and six core sections from Site 436 on the seaward side of the Japan Trench were obtained through the JOIDES Organic Geochemistry Advisory Panel for study of the origin and state of genesis of the organic matter associated with these continental slope, accretionary wedge, and outer trench slope sediments of the Japan Trench. The lipid fraction of these sediments is derived primarily from terrigenous organic matter and thus is allochthonous to the area. The associated kerogen fraction is of mixed allochthonous and autochthonous origin. The total organic carbon content seaward of the trench is less than that on the landward side. The composition of this organic matter is similar but not identical to that found in the landward side sediments. The organic matter within these sediments is in a diagenetic state in which geopolymerization of biogenic organic matter is nearly complete, but microbial alteration is still occurring.本研究通过综合大洋钻探计划（JOIDES）有机地球化学咨询小组，采集获取了日本海沟向陆侧434、435、438、439及440站位的43段岩芯剖面，以及向海侧436站位的6段岩芯剖面，用于探究与日本海沟大陆坡、增生楔及海沟外坡沉积物相关的有机质成因与形成状态。该类沉积物的脂类组分主要源自陆源有机质，因此属于该区域的异地成因有机质。与之伴生的干酪根组分则兼具异地与原地双重成因。海沟向海侧的总有机碳（total organic carbon）含量低于向陆侧沉积物。该有机质的组成与向陆侧沉积物中的有机质组成相似，但并非完全一致。这些沉积物中的有机质处于成岩作用阶段，其中生物成因有机质的地质聚合作用已近乎完成，但微生物改造作用仍在持续进行。