Active Silica Diagenesis in the Deepest Hadal Trench Sediments

Porewater dissolved silicic acid (DSi) concentrations and stable Si isotope compositions (δ30Si) together with biogenic silica (bSiO2) contents of sediments in five sediment cores collected from the southern Mariana Trench are presented. These data suggest occurrence bSiO2 dissolution concomitant authigenic clay formation three bSiO2-bearing cores. A reaction-transport model constrained by measured geochemical was applied to quantify rates turnover. Model results predicted greatest both at trench axis core that displayed low abundant detrital materials, suggesting materials may be a limiting factor for diagenesis. further ∼40%–70% DSi generated is consumed formation. This first study demonstrates active diagenesis hadal realm has implications understanding benthic cycling deep-sea settings.