Quantifying Iron Oxide Mineral Contents in Miocene Oceanic Red Beds for the Deep-Sea Oxidation Evolution in the South China Sea

The International Ocean Discovery Program (IODP) Expedition 349 recovered Miocene oceanic red beds overlying the basaltic basement in South China Sea. occurrence of provides an opportunity to understand deep-sea redox conditions when Sea was open western Pacific during Miocene. Here, we investigated iron oxide mineral contents along with major element compositions at Site U1433 reveal oxidation environment and its interaction Pacific. results show that these samples contain 0.20–1.48% hematite (average 0.50%) 0.30–2.98% goethite 1.20%). Their have good linear correlations color reflectance a* (red) b* (yellow), respectively, implying reddish-brown resulted from a mixture goethite. Compared other worldwide, is considered form under oxic bottom water extremely low sedimentation rate. (hematite + goethite)/(100%—Al 2 O 3 ) ratio adopted reconstruct evolution Early–Middle A continuously decreased trend 18.4 11.6 Ma, two strengthened events occurring around 15 Ma 14 observed dominate abyssal We infer this long-term caused by gradual blocking oxygen-rich since Early Miocene, while were likely attributed rapid thermal subsidence global cooling Middle climate transition, respectively.