Skeletal Grain types

Cephalopods

1. Ammonite

Upper half of a cross-section of an ammonite biomould filled by a crinoidal wackestone from a Jurassic basinal facies. The original shell composition was aragonitic and replaced by calcite spar.

Thin section kindly provided by T. Geel, Vrije Universiteit, Amsterdam

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2. Ammonite

Skeletal packstone with fragments of ammonites from Jurassic basinal facies.

Thin section kindly provided by T. Geel, Vrije Universiteit, Amsterdam

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3. Ammonite

Skeletal wackestone/floatstone with a section of ammonite geopetally filled by carbonate mud matrix and calcite spar associated with skeletal debris of bivalves, brachiopods and echinoderms.

Lower Jurassic, High Atlas, Morocco, cf. Merino-Tome' et al. (2012)

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4. Ammonite

Skeletal wackestone to packstone with an ammonite cross section on the left, bivalve shells on the right and a crinoid fragment in the upper right corner.

Lower Jurassic, High Atlas, Morocco, cf. Merino-Tome' et al. (2012)

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5. Ammonite

A particular of a fragment of ammonite shell replaced by calcite spar because of its original aragonite composition in a peloidal packstone.

Lower Jurassic, High Atlas, Morocco, cf. Merino-Tome' et al. (2012)

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6. Apthycus

Skeletal wackestone from a Jurassic basinal facies with an apthycus of ammonite (centre left). Apthyci were originally calcitic in composition.

Thin section kindly provided by T. Geel, Vrije Universiteit, Amsterdam

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7. Ammonite

Skeletal wackestone from a Jurassic slope facies showing in the centre left a section of ammonite shell filled by prismatic radial fibrous cement followed by limpid blocky sparite.

Lower Jurassic, High Atlas, Morocco, cf. Merino-Tome' et al. (2012)

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8. Ammonite

Skeletal peloidal packstone from a Jurassic outer ramp facies showing a cross section of an ammonite.

Lower Jurassic, High Atlas, Morocco, cf. Merino-Tome' et al. (2012)

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ammonite shell

crinoidal wackestone

ammonite shell with geopetal infill

ammonite shell

calcite spar

ammonite

bivalve

calcite spar within ammonite shell

ammonite Aptichus

radial fibrous cement

Cephalopods

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ammonite shell

crinoidal wackestone

ammonite shell with geopetal infill

ammonite shell

calcite spar

ammonite

bivalve

calcite spar within ammonite shell

ammonite Aptichus

radial fibrous cement