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Blastomylonite a mylonite that displays a significant

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Blastomylonite : A mylonite that displays a significant degree of grain growth related to or following deformation. Phyllonite : A phyllosilicate-rich mylonite that has the lustrous sheen of a phyllite. Cataclasite : A fault rock which is cohesive with a poorly developed or absent schistosity, or which is incohesive, characterised by generally angular porphyroclasts and lithic fragments in a finer-grained matrix of similar composition. Generally no preferred orientation of grains of individual fragments is present as a result of the deformation, but fractures may have a preferred orientation. A foliation is not generated unless the fragments are drawn out or new minerals grow during the deformation. Plastic deformation may be present but is always subordinate to some combination of fracturing, rotation and frictional sliding of particles. Cataclasite may be subdivided according to the relative proportion of finer-grained matrix into protocataclasite, mesocataclasite and ultracataclasite. Protocataclasite : A cataclasite in which the matrix forms less than 50% of the rock volume. Mesocataclasite : A cataclasite in which the matrix forms more than 50% and less than 90% of the rock volume . Note : As cataclasite is the general term, to be consistent it is necessary to have a prefix for the more specific term intermediate between proto- and ultracataclasite. Ultracataclasite : A cataclasite in which the matrix forms more than 90% of the rock volume. Fault Breccia : A medium- to coarse-grained cataclasite containing >30% visible fragments. www.bgs.ac.uk/scmr/home.html
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KHB Page 12 1/29/2007Paper_3.doc Fault Gouge : An incohesive, clay-rich fine- to ultrafine-grained cataclasite, which may possess a schistosity and containing <30% visible fragments. Lithic clasts may be present. Pseudotachylite : Ultrafine-grained vitreous-looking material, usually black and flinty in appearance, occuring as thin planar veins, injection veins or as a matrix to pseudo- conglomerates or breccias, which infills dilation fractures in the host rock. 7B REFERENCES Agricola (Bauer, G.), 1556. De re metallica, Libri XII, posthumous edition illustrated by H.R. Manuel. Frobenius, Basel , 538pp. (1 st edn in 1530) Barker, A.J., 1990. Introduction to Metamorphic Textures and Microstructures. Blackie. 162pp. Barth T.F.W., 1978. In, McGraw-Hill Encyclopedia of the Geological Sciences, (ed., Lapedes, D.N.). McGraw- Hill. 915pp. Bates R.L. and Jackson J.A 1987. Glossary of Geology (3 rd edition). American Geological Institute, Virginia, 788pp. Boullier, A.M. & Nicolas, A. 1975. Classification of textures and fabrics from peridotite xenoliths from South African Kimberlites. Physics and Chemistry of the Earth, (eds. Ahrens, L.H., Dawson, J.B. Duncan, A.R. & Erlank, A.J.), 9, 467-475. Pergamon Press. Darwin, C.
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Blastomylonite A mylonite that displays a significant...

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