CHLORITOID-STAUROLITE ASSEMBLAGES FROM BARROWS ZONES IN CENTRAL PERTHSHIRE, SCOTLAND

Chloritoid-biotite- and chloritoid-staurolite-bearing rocks occur around Blair Atholl, Perthshire. Textures suggest staurolite to be produced from chloritoid by a prograde ionic reaction involving muscovite. Chloritoid rocks are aluminous, lying above the muscovite-chlorite join, and staurolite formation involves the breakdown of chloritoid and muscovite. Their presence indicates that the chloritoid-biotite zone of Stonehaven continues as far SW as Central Perthshire, although its occurrence is severely limited by a lack of aluminium-rich rocks. The use of the chloritoid outcrop in the NE as an indication of pressure decrease to the SW is therefore queried. © 1979, Cambridge University Press. All rights reserved.