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Greywacke Sedimentation in the Torridonian of Colonsay and Oronsay

Published online by Cambridge University Press:  01 May 2009

A. D. Stewart
A. D. Stewart
Affiliation:
Institut für Gesteinskunde der Universität München, Luisenstrasse 37 a, 8 München, 2.
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Abstract

The lower Torridonian in its southernmost outcrops is built of felspathic greywacke turbidites, forming a succession probably 2–3 km. thick, overlain by 2 km. of pelitic and semi-pelitic sediments containing thick, current-bedded pebbly arkose horizons, especially near the base. Sedimentary structures in the greywackes include ubiquitous grading, together with flames, load-casts, convolute bedding, and sedimentary injection, brecciation and disruption phenomena. Palaeocurrents in both greywackes and arkoses indicate a southerly derivation. The detrital mineralogy also suggests a common provenance. It is suggested that the greywackes gradually filled their depositional basin and that later sedimentation occurred in a shallow water or fluvial environment.

Type
Articles
Information
Geological Magazine , Volume 99 , Issue 5 , October 1962 , pp. 399 - 419
Copyright
Copyright © Cambridge University Press 1962

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