Carbonate & Limestone Deposition

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What are limestones composed of
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Terms in this set (14)
What are limestones composed of
Greater than 50% CaCO3
Crystalline forms of limestone?
calcite and aragonite
Limestone makes up what percent of rock record?
10-15% Limestone (Sand/congl. = 20-25%, Mudrock= 60%)
Where do carbonates form?
in ocean basins or marine environments, typically warm shallow areas near no major rivers, max depth 200m
What is dolomite composed of?
CaMg(CaCO3)2, magnesium ions added & layered among Ca ions
5 types of carbonate platforms
Ramp: coast ramps up slightly
Rimmed shelf: clastic barrier reef
Epeiric: carbonates that form on continental crust
Isolated: Bahama's, carbonates formed as sea level rose
Drowned: sea level rise that created flat area
Biogenic sources of carbonates
skeletal fragments of mollusks, brachiopods, echinoderms, and forams that create fossiliferous limestone
Inorganic grains of carbonates
ooids: grains smaller than 2mm
pisoids: spherical grains larger than 2mm (red algae)
oncoids: non-spherical grains larger than 2mm
intraclasts: fragments of partially lithified carbonate mud
6 controls on carbonate deposition
Temperature
Pressure & CCD
Agitation
Organic Activity
Sediment masking
Light
Quiz question: Precipitation of limestone is promoted by any process that removes CO2 from water such as
Temperature change, pressure change, agitation, and organic activity
Quiz question: The rate at which shells of floating pelagic organisms is delivered to the deep ocean varies withwater temperature, latitude, water depth, and organic nutrientsQuiz Question: In limestone classification, ___________ are any grains of calcium carbonate that are transported after formationallochemsQuiz Question: In limestone classification, ___________ are any grains of calcium carbonate that are found where they are formedorthochemsQuiz Question: Ooids, Pisoids, and Peloids are examples ofallochems