Please use this identifier to cite or link to this item: https://hdl.handle.net/2440/1735
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Type: Journal article
Title: Sm-Nd and Zircon U-Pb ages from garnet-bearing eclogites, NE Oman: constraints on High-P metamorphism
Author: Gray, D.
Hand, M.
Mawby, J.
Armstrong, R.
Miller, J.
Gregory, R.
Citation: Earth and Planetary Science Letters, 2004; 222(2):407-422
Publisher: Elsevier Science BV
Issue Date: 2004
ISSN: 0012-821X
1385-013X
Statement of
Responsibility: 
David R. Gray, Martin Hand, Jo Mawby, Richard A. Armstrong, John McL. Miller and Robert T. Gregory
Abstract: Poly-deformed and poly-metamorphosed glaucophane-eclogite mega-boudins beneath the Samail Ophiolite, Oman record an early subduction-related high-P metamorphism as well as subsequent overprinting deformation and metamorphism related to exhumation. Previously published Rb/Sr ages of 78 Ma and 40Ar/39Ar ages of 82-79 Ma record the major NE-directed shearing event that partially exhumed the eclogites to a shallower crustal level. New Sm/Nd garnet-garnet leachate-whole rock isochron data from garnet-bearing eclogite assemblages in the As Sifah subwindow in NE Oman are 110±9 Ma (DG02-87D); 5-point isochron) and 109±13 Ma (DG02-86E; 3-point isochron). On the basis of microfabric and field structural relationships these ages are interpreted to reflect the timing of prograde, peak high-P metamorphism in the rocks structurally beneath the Samail Ophiolite. This metamorphism clearly predates the age of formation of the obducted Samail oceanic lithosphere (97-94 Ma) as well as the subsequent obduction onto the margin (80-70 Ma). A U-Pb SHRIMP zircon age from small (<200 μm in length) zircons with herring-bone textured zoning from DG02-87D indicate that rapid zircon growth associated with high-Si phengites occurred at 82±1 Ma. Zircon growth is possibly related to liberation of Zr on garnet breakdown during decompression metamorphism under high-P conditions with exhumation. These data require that crustal stacking models attendant with ophiolite obduction are inappropriate to explain the Oman high-P metamorphism. © 2004 Elsevier B.V. All rights reserved.
Keywords: subduction
eclogite facies
Oman
Sm–Nd dating
U–Pb SHRIMP zircon dating
DOI: 10.1016/j.epsl.2004.03.016
Description (link): http://www.elsevier.com/wps/find/journaldescription.cws_home/503328/description#description
Appears in Collections:Aurora harvest 2
Earth and Environmental Sciences publications
Environment Institute publications

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