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Polymetamorphism in the Dalradian of the central Scottish Highlands

Published online by Cambridge University Press:  01 May 2009

T. J. Dempster  and
B. Harte
T. J. Dempster
Affiliation:
Grant Institute of Geology, University of Edinburgh, West Mains Road, Edinburgh EH9 3JW, U.K.
B. Harte
Affiliation:
Grant Institute of Geology, University of Edinburgh, West Mains Road, Edinburgh EH9 3JW, U.K.
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Abstract

Systematic variations in both timing and conditions of metamorphism are observed in the Dalradian rocks of Central Perthshire, Scotland. Early (D2–D3 and syn-D3) relatively low-pressure metamorphism (550 °C, 7 kb) occurs in the Flat belt rocks of the Tay Nappe to the south, and later (post-D3) higher-pressure conditions (550 °C, 9 kb) dominate the Steep belt to the north. The latter appear to be superimposed on earlier low pressure assemblages (chloritoid–biotite) with the pressure increase probably relating to formation of the Tummel Steep Belt, possibly near 460 Ma. This polymetamorphism, in addition to the generally high pressures of Barrovian metamorphism throughout Perthshire, may account for the poor development of the metamorphic zonal pattern in this region compared to the eastern Dalradian.

Type
Articles
Information
Geological Magazine , Volume 123 , Issue 2 , March 1986 , pp. 95 - 104
Copyright
Copyright © Cambridge University Press 1986

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