Sedimentary Hydrodynamic Processes Under Low-Oxygen Conditions: Implications for Past, Present, and Future Oceans

• DOI: 10.3389/feart.2022.886395
• Publication Date: 2022-05-09T06:04:19Z
• Authors: Elena T. Bruni; Thomas M. Blattmann; Negar Haghipour; Deon Louw; Mark Lever; Timothy I. Eglinton
• Keywords: Authigenic; Sink (geography); Biogeochemical Cycle; Nepheloid layer

Continental margin sediments represent a major global sink of organic carbon (OC), and as such exert key control on Earth’s climate. Today, OC burial in marine mainly takes place under oxygen-rich water columns, where most is stabilized through intimate association with sediment grains biogenic minerals. In prior episodes past, when large parts the oceans were anoxic, mode sedimentary must have been very different, however. Present-day analogues indicate that surface accumulating low-oxygen columns are often “soupy” texture. Moreover, occurs (100–2,000 μm diameter) organo-mineral aggregates which, due to their low density, prone wave- current-induced resuspension. Upon mobilization, these can undergo lateral transport within so-called nepheloid layers, may be translocated hundreds kilometres, timescales thousands years. Little known about processes formation, resuspension hydrodynamic properties oxygen-poor waters, or which factors eventual breakdown burial. The goal this study examine drivers biogeochemical consequences cycling modern, oxygen-depleted, “Semi-Liquid Ocean Bottom” (SLOB) regions. We argue models OM hydrodynamics redistribution describe sedimentation oxygenated ocean waters modern poor analogue for equivalent occurring oxygen-deficient conditions. latter, we hypothesize 1) abundance low-density organic-rich particles leads greater propensity remobilization at low(er) shear stress, 2) upon into bottom remobilized subject less degradation (less attenuation) during transport, leading efficient widespread translocation distal centres deposition. address specific aspects SLOB hypothesis utilizing combination literature new data, focussing Benguela Upwelling Region model system.