The Micro-fabric of the Moine Schists

Abstract

Some years ago (Phillips, 1937) I published the results of a preliminary survey of the fabric of some Moine schists by the methods which have been evolved in that branch of the study of rocks now generally known as structural petrology. This survey showed that the quartz, muscovite, and biotite in all the specimens of Moine schist examined have the girdle-arrangement characteristic of a B-tectonic; that the b−axes of these girdles, over a large area of outcrop, plunge in a south-easterly direction; and that the direction of the b−axis of a given specimen is frequently marked by a visible lineation on the foliation-surface of the schist. Study of the fabric of Moine schists visibly affected by the dislocation-phase of the post-Cambrian movements was shown to afford support for the view, already advanced by others on the basis of petrographic study, that the ultimate effect of these movements on the Moine schists is to break down the previously existing fabric; there is a dislocation-metamorphism “undoubtedly superposed upon the general Moine metamorphism” (Read, 1934, p. 307).