Dalradian-?Arenig relations in parts of the Highland Border, Scotland, and their significance in the chronology of the Caledonian orogeny

Abstract

SynopsisComparisons of structures in the Jasper and Green Rocks (J.G.R.) (?Arenig) and Dalradian exposed in the River North Esk, near Edzell, lead to the following correlations which are presented in conjunction with the possibly equivalent events in the Central Highland regional history. North EskCentral Highlands Regional HistoryJ. and G. RocksDalradianNear-isoclinal folds with flow cleavageNear-isoclinal folds with flow cleavageGrowth of biotite porphyroblastsF1 (Tay Nappe, Aberfoyle anticline) Climax of regional metamorphismTight folds with axial planar strain-slip cleavageTight folds with axial planar strain-slip cleavageF3 (Ben Ledi antiform, [‘downbend’], Cowal antiform)Two sets of corrugations and kink bandsTwo sets of open folds and crenulationsF4 etc.These correlations are supported by evidence that the ?Arenig in Arran is downward facing.