Influence of Early Low‐Temperature and Later High‐Temperature Diagenesis on Magnetic Mineral Assemblages in Marine Sediments From the Nankai Trough

Abstract Diagenesis can have a major impact on sedimentary mineralogy. Primary magnetic mineral assemblages be modified significantly by dissolution or formation of new minerals during early late diagenesis. At International Ocean Discovery Program Site C0023, which was drilled in the protothrust zone Nankai Trough Expedition 370, offshore Shikoku Island, Japan, non‐steady state conditions produced complex sequence overprints. Detailed rock measurements, characterize terms abundance, grain size, and composition, were conducted to assess alteration diagenetic overprinting. Four zones (MZs) are identified down‐core from ∼200 1,100 m below sea floor based variations. MZ 1 is high intensity that contains ferrimagnetic greigite, formed at shallow depths preserved because rapid sedimentation. MZs 2 4 low with fewer minerals, mainly coarse‐grained (titano‐)magnetite hematite. This assemblage remnant more altered diagenetically few million years after deposition when site entered Trough. 3 between 4. It authigenic single‐domain particles probably fluids circulated through faults accretionary prism. Varying sediment supply organic matter input time, burial temperature, tectonic fluid circulation primary drivers