The influence of tectonic migration of ocean floor on (bio-)geochemical and diagenetic processes in subseafloor sediments from the Nankai Trough off Japan

Abstract

(Bio-)geochemical processes in subseafloor sediments are closely coupled to global element cycles. To gain an improved understanding of changes in (bio-)geochemical conditions on geological timescales, we investigate sediment cores from a 1180 m deep hole in the Nankai Trough offshore Japan (Site C0023). The sediment cores were taken during International Ocean Discovery Program (IODP) Expedition 370 (Temperature Limit of the Deep Biosphere off Muroto), which aimed at exploring the prerequisites and limits of deep microbial life [1]. Over the past 15 Ma, Site C0023 has moved ~750 km relative to its present-day geographic position from the central Shikoku Basin to the Nankai Trough due to motion of the Philippine Sea plate [2]. During its tectonic migration, Site C0023 has experienced significant changes in depositional and thermal conditions as well as resulting (bio-)geochemical processes.