BGS Rock Classification Scheme
Cataclastic-rock - A type of unfoliated mechanically broken rock with primary cohesion. These rocks are formed at higher confining pressures than those without cohesion. The nature of the rocks depends on factors such as confining pressure, original lithology, amount and duration of movement, and the availability of fluids. Cataclastic rocks exhibit grain size reduction by fragmentation of grains during deformation. In the Rock Classification Scheme, they are classified as protocataclasite, cataclasite, and ultracataclasite on the relative proportions of fragments and matrix. British Geological Survey Research Report RR/99/02, section 7.2 and table 4.
| Code | CATR |
|---|---|
| Description | Cataclastic-rock - A type of unfoliated mechanically broken rock with primary cohesion. These rocks are formed at higher confining pressures than those without cohesion. The nature of the rocks depends on factors such as confining pressure, original lithology, amount and duration of movement, and the availability of fluids. Cataclastic rocks exhibit grain size reduction by fragmentation of grains during deformation. In the Rock Classification Scheme, they are classified as protocataclasite, cataclasite, and ultracataclasite on the relative proportions of fragments and matrix. British Geological Survey Research Report RR/99/02, section 7.2 and table 4. |
| Qualifiers | No qualifiers currently exist. |
| Definition | Deformed (brittle), unfoliated rock with primary cohesion (protolith undefined) comprising 10-50% fragments in a finer grained matrix, grain size reduction by mechanical fragmentation +/- recrystallisation of matrix. |
| Linked data | http://data.bgs.ac.uk/id/EarthMaterialClass/RockName/CATR |
CAVEAT
"Thumbnail" definitions attached to some of the table entries are an interim attempt to provide simple short descriptions of the "unqualified" rock types presented within the BGS Rock Classification Scheme. Every effort has been made to ensure accuracy and consistency but minor contradictions or omissions might be present. The BGS welcomes any feedback pointing out such minor imperfections and/or providing constructive comment and suggestions for improvement of the definitions. In the first instance such feedback should be directed to Dr Tim McCormick.