Marine sediment

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Sediments
By origin Terrigenous (lithogenous) Biogenous Cosmogenous Hydrogenous
By texture Roundness Sorting Grain size boulder cobble gravel pebble granule sand silt clay colloid Other oolite scree till
By composition Manganese nodules Oolitic aragonite sand Tektites
By process Sedimentation Sedimentary budget Sediment transport coastal Weathering Erosion Aeolian (windborne) transport Biomineralization Bioturbation Compaction Concretion Exner equation Fluvial processes Glacier flow ice-sheet dynamics ice rafting Lithification Siltation Turbidity currents
By structure Sedimentary structures Bedforms cross-bedding duness graded bedding ripple marks Alluvial fan Alluvial river Fault Fold Paleocurrent indicators sole markings imbrication River delta Sediment–water interface Sedimentary basin Soft-sediment deformation Unconformity Vegetation-induced
Soil sediment Soil matrix pore space permeability morphology texture value color Catena Soil horizon Humus Humin Soil salinity Hydropedology Mineralization Microbial calcite precipitation
Marine sediment Abyssal fan Aragonite aragonite sea oolitic aragonite sand Calcite calcite sea Amorphous calcium carbonate Calcification Continental rise Bay mud Bioirrigation Coastal sediment transport Coastal sediment supply Evaporites Marine clay pelagic red clay Marine regression transgression Pelagic turbidite contourite hemipelagite Salt tectonics Sedimentary basin Tidal bundle
Biogenous sediments Calcareous ooze biogenic calcification calcareous nannoplankton Siliceous ooze biogenic silica silicification diatomaceous earth radiolarite Microfossil Reverse weathering
Sedimentary ecology Soil biomantle Soil zoology soil pathogens Pedodiversity Soil biodiversity Rhizosphere root microbiome
Sedimentary carbon Soil carbon storage Soil carbon Coal Peat
Sedimentary rock Badlands Carbonates limestone dolomite Clastic conglomerate breccia sandstone mudrock Evaporite Chalk Chert Greywacke Iron-rich Organic-rich Phosphorite Siliceous
Related History geology geological paleontology soil science Legacy sediment Principles cross-cutting relationships lateral continuity original horizontality Provenance Sedimentary record Sedimentology Stratigraphy Rock cycle calcium silica carbonate-silicate Paleolimnology Biosignature
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Marine sediment, or ocean sediment, or seafloor sediment, are deposits of insoluble particles that have accumulated on the seafloor. These particles either have their origins in soil and rocks and have been transported from the land to the sea, mainly by rivers but also by dust carried by wind and by the flow of glaciers into the sea, or they are biogenic deposits from marine organisms or from chemical precipitation in seawater, as well as from underwater volcanoes and meteorite debris.

Except within a few kilometres of a mid-ocean ridge, where the volcanic rock is still relatively young, most parts of the seafloor are covered in sediment. This material comes from several different sources and is highly variable in composition. Seafloor sediment can range in thickness from a few millimetres to several tens of kilometres. Near the surface seafloor sediment remains unconsolidated, but at depths of hundreds to thousands of metres the sediment becomes lithified (turned to rock).

Rates of sediment accumulation are relatively slow throughout most of the ocean, in many cases taking thousands of years for any significant deposits to form. Sediment transported from the land accumulates the fastest, on the order of one metre or more per thousand years for coarser particles. However, sedimentation rates near the mouths of large rivers with high discharge can be orders of magnitude higher. Biogenous oozes accumulate at a rate of about one centimetre per thousand years, while small clay particles are deposited in the deep ocean at around one millimetre per thousand years.

Sediments from the land are deposited on the continental margins by surface runoff, river discharge, and other processes. Turbidity currents can transport this sediment down the continental slope to the deep ocean floor. The deep ocean floor undergoes its own process of spreading out from the mid-ocean ridge, and then slowly subducts accumulated sediment on the deep floor into the molten interior of the earth. In turn, molten material from the interior returns to the surface of the earth in the form of lava flows and emissions from deep sea hydrothermal vents, ensuring the process continues indefinitely. The sediments provide habitat for a multitude of marine life, particularly of marine microorganisms. Their fossilized remains contain information about past climates, plate tectonics, ocean circulation patterns, and the timing of major extinctions.^[1]