Chapter Overview Marine Sediments Marine Sediment Classification

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Biogenous SedimentComposition• Two most common chemical compounds:– Calcium carbonate (CaCO 3 )– Silica (SiO 2 or SiO 2·nH 2 O)Calcium Carbonate in BiogenicSediments• Coccolithophores– Also callednannoplankton– Photosynthetic algae– Coccoliths – individualplates from deadorganism– Rock chalk• Lithified coccolithrichooze© 2011 Pearson Education, Inc.© 2011 Pearson Education, Inc.Silica in Biogenous Sediments•Diatoms– Photosyntheticalgae– Diatomaceousearth• Radiolarians– Protozoans– Use externalfoodCalcium Carbonate in BiogenicSediments• Foraminifera– Protozoans– Use externalfood– Calcareous ooze© 2011 Pearson Education, Inc.© 2011 Pearson Education, Inc.Silica in Biogenous Sediments• Tests from diatomsand radiolariansgenerate siliceousooze.• Siliceous ooze lithifiesinto diatomaceousearth.Distribution of BiogenousSediments• Depends on three processes:– Productivity– Destruction– Dilution© 2011 Pearson Education, Inc.© 2011 Pearson Education, Inc.
Neritic Deposits• Dominated by lithogenous sediment, maycontain biogenous sediment• Carbonate Deposits– Carbonate minerals containing CO 3– Marine carbonates primarily limestone –CaCO 3– Most limestones contain fossil shells• Suggests biogenous origin– Ancient marine carbonates constitute 25% ofall sedimentary rocks on Earth.Calcareous Oozeand theCCD© 2011 Pearson Education, Inc.© 2011 Pearson Education, Inc.Carbonate Deposits• Stromatolites– Fine layers ofcarbonate– Warm, shallow-ocean,high salinity– CyanobacteriaCalcareous Ooze and the CCD• Scarce calcareous ooze below 5000 meters(16,400 feet) in modern ocean• Ancient calcareous oozes at greater depths ifmoved by sea floor spreading© 2011 Pearson Education, Inc.© 2011 Pearson Education, Inc.Calcareous Ooze and the CCD• CCD – Calcite compensation depth– Depth where CaCO 3 readily dissolves– Rate of supply = rate at which the shellsdissolve• Warm, shallow ocean saturated withcalcium carbonate• Cool, deep ocean undersaturated withcalcium carbonate– Lysocline – depth at which a significantamount of CaCO 3 begins to dissolve rapidly© 2011 Pearson Education, Inc.Sea Floor Spreading and SedimentAccumulation© 2011 Pearson Education, Inc.
Page 1 and 2: CHAPTER 4Marine SedimentsPaleoceano
Page 3: Sediment Texture• Grain size sort
Page 8: Worldwide Marine Sediment Thickness

Chapter Overview Marine Sediments Marine Sediment Classification

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