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Tectonic position of the Dalradian rocks of Connemara and its bearing on the evolution of the Midland Valley of Scotland

Published online by Cambridge University Press:  03 November 2011

Bernard E. Leake ,
P. W. Geoff Tanner ,
R. M. Macintyre  and
E. Elias
Bernard E. Leake
Affiliation:
Department of Geology, University of Glasgow, Glasgow G12 8QQ, Scotland.
P. W. Geoff Tanner
Affiliation:
Department of Geology, University of Glasgow, Glasgow G12 8QQ, Scotland.
R. M. Macintyre
Affiliation:
Isotope Geology Unit, Scottish Universities Research and Reactor Centre, East Kilbride, Glasgow G75 OQU, Scotland.
E. Elias
Affiliation:
Department of Geology, University of Glasgow, Glasgow G12 8QQ, Scotland.
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Abstract

The Dalradian terrane of Connemara was thrust southsoutheastwards about 460 Ma ago (Rb–Sr and K–Ar ages). It rides on a major thrust of post-D age over mylonitised acidic volcanic rocks of putative lower Ordovician age and contains a number of thrusts of similar age. Several major S- to SE-directed thrusts also limit the southeastern margin of the Dalradian rocks in Mayo and Tyrone. It is suggested by analogy with Ireland that during mid-Ordovician times the Highland Boundary fault in Scotland could have been a thrust zone which carried the Scottish Dalradian rocks over a lower Ordovician basement now represented only as fragments in the Highland Border Complex.

Keywords

basicConnemaraHighland Boundary faulthornblendeIrelandK–Ar datingmyloniteOrdovicianrhyolitethrustingultrabasic
Type
Highland Border and Dalradian terranes
Information
Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 75 , Issue 2: Deep Geology of the Midland Valley of Scotland and Adjacent Regions. Bicentenary Symposium , 1984 , pp. 165 - 171
Copyright
Copyright © Royal Society of Edinburgh 1984

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