Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/68483
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Type: Journal article
Title: P-T constraints and timing of Barrovian metamorphism in the Shetland Islands, Scottish Caledonides: implications for the structural setting of the Unst ophiolite
Author: Cutts, K.
Hand, M.
Kelsey, D.
Strachan, R.
Citation: Journal of the Geological Society, 2011; 168(6):1265-1284
Publisher: Geological Soc Publ House
Issue Date: 2011
ISSN: 0016-7649
2041-479X
Statement of
Responsibility: 
K. A. Cutts, M. Hand, D. E. Kelsey and R. A. Strachan
Abstract: An integrated in situ monazite laser-ablation inductively coupled plasma mass spectrometry and metamorphic equilibria study is used to establish the P–T conditions and timing of Barrovian metamorphism in the Shetland Islands, Scottish Caledonides. The results have implications for the structural setting of the Unst ophiolite, which was obducted onto metasedimentary rocks of the Dalradian Supergroup. Metapelites in the footwall of the ophiolite yield U–Pb ages between 462 and 451 Ma with P–T conditions varying from c. 7.5 kbar and 550 °C directly below the ophiolite to c. 10 kbar and 775 °C at structurally deeper levels. The timing of peak metamorphism corresponds closely to that of Grampian (c. 450–470 Ma) metamorphism in mainland Scotland and Ireland, and Taconic (c. 450–460 Ma) metamorphism in the Appalachians, thus confirming the near-synchroneity of this important arc accretion event along the Laurentian margin. There is a significant metamorphic contrast between the low-grade rocks associated with the Unst ophiolite and the P–T conditions recorded in its footwall. If published K–Ar ages of c. 470 Ma broadly record obduction of the ophiolite, its present basal contact is probably a younger tectonic break that was associated with the excision of at least c. 10 km of crustal section.
Rights: © The Geological Society of London
RMID: 0020114434
DOI: 10.1144/0016-76492010-165
Appears in Collections:Earth and Environmental Sciences publications
Environment Institute publications

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