Sediments

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Sediments
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Sediment thickness of ocean floor

• Very thin
• Mid-Atlantic ridge
• Very thick
• Smooth sea floor

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Sediment Texture and color

• Grain size
• Boulders to colloids
• Color
• White or creamy biological origin
• Gray high in silica
• Red clay- iron oxide

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Sediment classification by particle size

• Boulder gt256 mm
• Cobble 64-256 mm
• Pebble 4 64 mm
• Granule 2-4 mm
• Sand 0.062 2mm
• Silt 0.004 0.062 mm
• Clay lt0.004 mm

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Types of sediment

• Well-sorted sediments
• Particles of one size
• Poorly sorted sediments
• A mixture of size

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Sediment transport

• Rivers
• Glaciers
• Currents

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Classification of Marine sedimentby source

• Terrigenous Sediments
• Biogenous Sediments
• Hydrogenous Sediments
• Cosmogenous Sediments

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Terrigenous (lithogenous) Sediments

• Originates on the continents
• derived from igneous rocks
• Granite - the source of quartz and clay

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Biogenous Sediments

• Made of siliceous and calcareous compounds
• near continental margins

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Hydrogenous Sediments

• Minerals that have precipitated directly from sea
  water
• Eg manganese nodules
• Phosphorite nodules

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Cosmogenous Sediments

• Extraterrestrial origin
• microtektites.

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Distribution of Marine Sediments

• Neritic sediments
• Pelagic sediments

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Average thickness of marine sediments

• Continental shelves 2.5 Km
• Continental slopes 9 km
• Continental rises 8 km
• Deep ocean floor 0.6 km

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Sediments of continental margins

• Terrigenous
• lithification

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Sediment thickness of Deep-Ocean Basin

• Atlantic and Pacific
• abyssal plains
• oceanic ridges

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Sediments of Deep Ocean Basin

• Turbidites
• Clays
• Oozes
• Hydrogenous Materials

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Hydrogenous sediments

• Originate from chemical reaction Evaporites
• Eg, calcium carbonate,
• Calcium sulfate
• Sodium chloride
• Oolite sand

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Studying Sediments

• clamshell sampler
• piston corer

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stratigraphy
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Paleoceanography

• The study of the Oceans past

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The Economic Importance of Marine Sediments

• crude oil
• natural gas