carbonate rockscarbonate rocks •they form chemically and biochemically. •dissolved ions carried...
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Carbonate Rocks
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Carbonate Rocks
• Limestone and dolomites• They are called carbonate rocks because
they contain large amounts of carbonate(CO3).
• Carbonate rocks are the most abundant non-terrigenous sedimentary rock.
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Carbonate Rocks• They form chemically and biochemically.• Dissolved ions carried from source to
depositional site in solution eventuallyprecipitate and form solid minerals.
• Organism have a role in their formation. Theyextract dissolved components from sea-waterto manufacture shells or skeletons that later areincorporated in the sedimentary record. Theycan also modify the geochemical settingenough to cause mineral precipitation.
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Carbonate Geochemistry
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Controls on Carbonate Deposition• Temperature- rising the temperature results in
limestone deposition.• Pressure- reducing the pressure results in
limestone deposition (gas escape).• Degree of agitation- Breaking waves results in
limestone deposition (gas escape).• Organic activity- Plants and animals either
directly precipitate calcium carbonates ormodify the geochemical environment enoughfor precipitation to occur.
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• Light- because photosynthetic organismextract CO2 it results in carbonateprecipitation (water shallow enough less than20 meters).
• CCD
Controls on CarbonateDeposition
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Limestone classification
• Folk (1959, 1962)• Dunham (1962) and Embry and Klovan
(1972) Modification of Dunhamclassification
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Folk (1959, 1962)
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Textural maturity classificationof limestone proposed by Folk
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Classification of limestoneproposed by Dunham (1962)
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Embry and Klovan (1972) Modificationof Dunham classification