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VI.—Metamorphic Correlation in the Polymetamorphic Rocks of the Valla Field Block, Unst, Shetland Islands

Published online by Cambridge University Press:  06 July 2012

H. H. Read
H. H. Read
Affiliation:
George Herdman Professor of Geology in the University of Liverpool.
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Extract

In my account (Read, 1935) of the metamorphic geology of Unst, in the Shetlands, I have shown that the island is made up of a series of tectonic units separated from one another by dislocations of various kinds. The rocks of most of the units have lengthy metamorphic histories that are different in the different units.

This present communication deals with one tectonic unit, the Valla Field Block. The metamorphic history of this block can be divided into three stages, each characterized by the type of pressure-temperature factors operative during it. It is my main purpose here first to give the evidence, derived from the study of the pelitic rocks, on which this subdivision is based, and then to examine the behaviour of the various other rock-types during the three episodes. The results show that the stability of certain minerals depends upon the bulk-composition of the rocks containing them. In polymetamorphism of the Unst type, the minerals cannot be considered apart from the rocks in which they occur—a point of importance for Highland geology in general.

Type
Research Article
Information
Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 59 , Issue 1 , March 1937 , pp. 195 - 221
Copyright
Copyright © Royal Society of Edinburgh 1937

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References

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