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Title: Metamorphic and structural history of Glenelg, NW Scotland
Author: Salt, Christopher James
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1995
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The Glenelg peninsular in NW Scotland contains Lewisian type rocks occurring east of the Moine thrust that have been metamorphosed and deformed along with the Moine rocks. These Lewisian rocks can be split into two facies, the Eastern Lewisian and the Western Lewisian, always separated by a thin strip of highly deformed Moine rocks. The Western Lewisian contains no recognisable meta-sediments, only a variety of meta-igneous rocks. Eclogite is rare, only occurring at one locality as pods within otherwise deformed amphibolite facies rocks. These eclogites exhibit broadly similar textures to the Eastern Lewisian eclogites, but have a slightly different chemistry, being more Si rich and Ca poor. They are formed under similar conditions of about 760°C, 15 Kb, but only one metamorphic event has been distinguished. Many of the amphibolites of the Western Lewisian have similar textures and chemistry as partly retrogressed Western Lewisian eclogite. These rocks were deformed to produce a weak fabric prior to the intrusion of further basic material that is texturally and chemically different to the eclogites. All of these rocks were then deformed and metamorphosed by the syn-Moine deformation as outlined above for the Eastern Lewisian. It is suggested that the Eastern and Western Lewisian rocks share a common history of initial high-pressure metamorphism, then the intrusion of granitic melt prior to further high pressure metamorphism. This was followed by deformation and partial retrogression before the intrusion of basic and ultrabasic dykes. The Lewisian rocks were then exhumed and the Moine rocks deposited onto them prior to further deformation and metamorphism. Radiometric dating suggests that the high pressure metamorphism occurred at approximately 1050 Ma (Grenville), but field and petrographic evidence suggests that the Lewisian rocks have undergone a similar history to the Scourian rocks of the main Lewisian outcrop and that Grenville ages for the rocks date initial syn- Moine metamorphism.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available