Table of Contents
Textures and Microstructures
Volume 4 (1982), Issue 4, Pages 211-221

Fault Rocks of the Moine Thrust Zone: A Guide to Their Nomenclature

Geology Department, Imperial College, London SW7 2BP, UK

Received 24 April 1981; Accepted 15 July 1981

Copyright © 1982 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The aim of this article is to extract from the existing literature a consistent nomenclature that can be used in the description of coherent fault rocks. The nomenclature is dealt with in this paper. Typical microstructures illustrating each is presented in a later paper (White et al ., 1982). It will be shown that a simple set of nomenclature can be extracted from the literature, so long as genetic connotations are kept to a minimum. The sequence, with increasing shear strain is country rock–protomylonite–blastomylonite–mylonite–ultramylonite if the rock has a well developed foliation; country rock–protocataclasite–cataclasite–ultracataclasite if it is without a foliation.

It is emphasized that a mylonite is basically a fine-grained schist that has formed within fault zones. It is the association with faulting that distinguishes a mylonite from a fine grain schist.