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Carbonate

Components

Principal Types of

Skeletal Grains

Molluscs(aragonite)

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Corals(aragonite)

Foraminifera(calcite)

Bryazoans(magnesian calcite)

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Brachiopods(calcite)

Coccoliths(calcite)

Green Algae(aragonite)

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Cyanobacteria (Blue-Green Algae)(non-calcifying)

How Does One Distinguish

Molluscs from Brachiopods?

Summary

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Environments of

Dissolution

Lysocline

The ocean depth at

which the rate of

calcium carbonate

dissolution

increases rapidly

with depth.Lysocline

Carbonate Compensation Depth

The ocean depth below which calcium carbonate is not

part of the sediment record.

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Chalk Reservoirs

Surface Dissolution: Karst

Surface

Dissolution:

Karst

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Surface Dissolution: Karst

Surface Dissolution: Karst

Subsurface Dissolution: Vuggy Porosity

Clyde H. Moore photomicrograph

Beavington-Penney et al., 2008 

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Subsurface Dissolution: Stylolites

Summary

Icehouse vs.Greenhouse Earth

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Aragonite Ooids

Tangential Texture

Magnesian Calcite Ooids

Radial Texture

Aragonite Marine Cement

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Magnesian Calcite Marine Cement

Scholle and Ulmer -

Scholle

Inorganic Carbonate Mineralogy and Icehouse

vs. Greenhouse Conditions

Icehouse ConditionsPrimary Marine Precipitate is Aragonite

Cool Temperatures, Continental GlaciersLow CO2 (low volcanism)

Greenhouse ConditionsPrimary Marine Precipitate is Magnesian Calcite

Warm Temperatures, No Glaciers

High CO2 (high volcanism)

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Icehouse Conditions

Cin-Ty Lee

Greenhouse Conditions

Cin-Ty Lee

Secular Changes in 18O and 13C of Marine

Carbonates during Phaner ozoic Time

Kygar C. Lohmann

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Stable Isotopes, Icehouse vs. Greenhouse Conditions,

and Sea Level

James and Choquette, 1990, after many others

Summary

Carbonate RockComponents

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Wentworth-

Udden

Sediment

Size Scale

Matrix: Micrite

Matrix: Spar

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Alochems: Intraclasts

Alochems: Ooids

Alochems: Fossils

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Alochems: Pellets

Just to make this as

confusing as

possible … 

Micrite May be Either Muddy Sediment

or Cement

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Spar may be Either Cement

or Replacement Crystals

Pellets May be Either Faecal Matter

or Micritized Grains

SEPM

Summary