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Geol 464: Carbonate GeologySemester 0622007

Lecture 6


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Classification Schemes: Dunham

Classification

Dunham Classification

Texture and allochem type

incorporated into

classification sediment deposited in calmvs agitated waters

grain vs mud support

mud-bearing vs mud-freesediment

bound (biologically)

depositional texturerecognizable


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5 mm5 mm 5 mm 5 mm5 mm

Rudstone(large grains)

Bindstone

Bafflestone

FramestoneFloatstone(large grains)

5 mm

30 mm 30 mm 30 mm

1m

100 mm

100 mm

Depositional texture recognizable

Components not bound together during deposition

Mud supported

Contains carbonate mud(clay / fine silt)

Lacks mudand is

grainsupportedGrainsupported

Componentswere bound

togetherduring

deposition

Depositionaltexture not

recognizable

Less than10% grains

More than10% grains

Mudstone Wackestone Packstone Grainstone Boundstone Crystalline

Dunhams Classification

with modifications by Embry and Klovan

Is based upon:

Binding or control of texture by in-placeorganisms

Recognition of the texture and fabric of the rock

Amount of lime mud Support of the grains

Amount of grains


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Is depositional texture recognizable?



Bindstone

Bafflestone


5 mm

30 mm 30 mm 30 mm

1m

100 mm

100 mm



Mud supported


Lacks mudand is



togetherduring

deposition


recognizable

Less than10% grains

More than10% grains



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Silicified Oolitic Grainstone (secondary replacement of carbonate by quartz)


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Ooid lime grainstone


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Rock contains mud. Is the rock

grain or mud supported?



Bindstone

Bafflestone


5 mm

30 mm 30 mm 30 mm

1m

100 mm

100 mm



Mud supported


Lacks mudand is



togetherduring

deposition


recognizable

Less than10% grains

More than10% grains



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Crinoidal packstone

The crinoid skeletal fragments are an off white to greyish brown color,whereas the matrix is yellowish brown.


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Mollusk/echinoid lime packstone


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If the rock is mud supported, is there

more than 10% grains?



Bindstone

Bafflestone


5 mm

30 mm 30 mm 30 mm

1m

100 mm

100 mm



Mud supported


Lacks mudand is



togetherduring

deposition


recognizable

Less than10% grains

More than10% grains



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Wackestones are carbonate rocks which are matrix-supported; i.e.,

there are more than 10% grains, but the fine grain clay size matrix

essentially surrounds the grains.

ilif li k


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Fossiliferous lime wackestone

If h k i d d i h


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Bindstone

Bafflestone


5 mm

30 mm 30 mm 30 mm

1m

100 mm

100 mm



Mud supported


Lacks mudand is



togetherduring

deposition


recognizable

Less than10% grains

More than10% grains


If the rock is mud supported, is there

more than 10% grains?

Li M d


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Lime Mudstone

M difi ti b E b d Kl (1972)


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Bindstone

Bafflestone


5 mm

30 mm 30 mm 30 mm

1m

100 mm

100 mm



Mud supported


Lacks mudand is



togetherduring

deposition


recognizable

Less than10% grains

More than10% grains


Modifications by Embry and Klovan (1972)

M difi ti b E b d Kl (1972)


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Floatstone(large grains)

30 mm

2.5 cm

Lime rudist floatstone



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Bindstone

Bafflestone


5 mm

30 mm 30 mm 30 mm

1m

100 mm

100 mm



Mud supported


Lacks mudand is



togetherduring

deposition


recognizable

Less than10% grains

More than10% grains




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30 mm 30 mm

2.5 cm

Lime rudist grain-rich rudstone



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Bindstone

Bafflestone


5 mm

30 mm 30 mm 30 mm

1m

100 mm

100 mm



Mud supported


Lacks mudand is



togetherduring

deposition


recognizable

Less than10% grains

More than10% grains





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Bafflestone100 mm

Bindstone100 mm

Framestone1m5 mm

Framestone

Boundstone


Framestone Modifications by Embry


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Framestone1m

Modifications by Embry

and Klovan (1972)

Lime coral framestone

Bindstone Modifications by Embry


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Bindstone100 mm


and Klovan (1972)

Algal stromatolite dolobindstone

Bafflestone Modifications by Embry


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Bafflestone100 mm


and Klovan (1972)

Algal-plate limebafflestone

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