Controls on the distribution of deep‐sea sediments

Abstract

Deep‐sea sediments represent the largest geological deposit on Earth and provide a record of our planet's response to conditions at the sea surface from where the bulk of material originates. We use a machine learning method to analyze how the distribution of 14,400 deep‐sea sediment sample lithologies is connected to bathymetry and surface oceanographic parameters. Our probabilistic Gaussian process classifier shows that the geographic occurrence of five major lithologies in the world's ocean can be predicted using just three parameters. Sea‐surface salinity and temperature provide a major control for the growth and composition of plankton and specific ranges are also associated with the influx of non‐aerosol terrigenous material into the ocean, while bathymetry is an important parameter for discriminating the occurrence of calcareous sediment, clay and coarse lithogenous sediment from each other. We find that calcareous and siliceous oozes are not linked to high surface productivity. Diatom and radiolarian oozes are associated with low salinities at the surface but with discrete ranges of temperatures, reflecting the diversity of planktonic species in different climatic zones. Biosiliceous sediments cannot be used to infer paleodepth, but are good indicators of paleotemperature and paleosalinity. Our analysis provides a new framework for constraining paleosurface ocean environments from the geological record of deep‐sea sediments. It shows that small shifts in salinity and temperature significantly affect the lithology of seafloor sediment. As deep‐sea sediments represent the largest carbon sink on Earth these shifts need to be considered in the context of global ocean warming.

GlobSed: Updated Total Sediment Thickness in the World's Oceans

“…There are numerous factors controlling sediment distribution in different ocean basins; among them are the tectonic history, age of the oceanic basin, structural trends in the basement including mid‐ocean ridges, fracture zones, the nature and location of sediment sources, preglacial and glacial transport and deposition, ocean circulation, and chemical composition (e.g., Divins, ; Dutkiewicz, Müller, et al, ; Dutkiewicz, O'Callaghan, et al, ; Olson et al, ). Describing the sediment thickness distribution in the oceans as dependent on only two variables (age and latitude) is a simplification; however, they seem to show consistent trends with global sediment distribution in global oceans (Müller, Sdrolias, Gaina, Steinberger, et al, ; Olson et al, ).…”

Planktonic foraminifera-derived environmental DNA extracted from abyssal sediments preserves patterns of plankton macroecology

“…They are found from tropical to polar water masses and spend their entire life cycle in the plankton (Hemleben et al, 1989). After their death, planktonic foraminifera sink to the bottom of the ocean, where they are found in the calcareous ooze, ranging from ∼ 1 to 4.5 km water depth and distributed from low to high latitudes (Dutkiewicz et al, 2016). The fossil planktonic assemblages are preserved without taxonomic bias above the lysocline and become increasingly affected by the preferential dissolution of thin-shell species below this limit (Berger and Parker, 1970).…”

Impact of Inorganic Particles of Sedimentary Origin on Global Dissolved Iron and Phytoplankton Distribution

“…A noticeable assumption in our simulations is to set the dissolution rate to a constant and globally uniform value. Regional differences in the dominant types of sediment (Dutkiewicz et al, ) make this assumption very unlikely as Cheize et al () demonstrated differences in the dissolution kinetics of three types of sediment from very close locations (i.e., Kerguelen islands; Figure ). One way to improve our parameterization would be to use regional dissolution rates.…”