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Sm-Nd and Zircon U-Pb ages from garnet-bearing eclogites, NE Oman: constraints on High-P metamorphism

Gray, Derek; Hand, Martin; Mawby, Jo; Armstrong, Richard; Miller, Jodie; Gregory, Robert T

Description

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...[Show more]

dc.contributor.authorGray, Derek
dc.contributor.authorHand, Martin
dc.contributor.authorMawby, Jo
dc.contributor.authorArmstrong, Richard
dc.contributor.authorMiller, Jodie
dc.contributor.authorGregory, Robert T
dc.date.accessioned2015-12-13T23:09:00Z
dc.identifier.issn0012-821X
dc.identifier.urihttp://hdl.handle.net/1885/86822
dc.description.abstractPoly-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.
dc.publisherElsevier
dc.sourceEarth and Planetary Science Letters
dc.subjectKeywords: Cretaceous; eclogite; neodymium; samarium; subduction; ultrahigh pressure metamorphism; uranium-lead dating; zircon; Asia; Eurasia; Middle East; Oman Eclogite facies; Oman; Sm-Nd dating; Subduction; U-Pb SHRIMP zircon dating
dc.titleSm-Nd and Zircon U-Pb ages from garnet-bearing eclogites, NE Oman: constraints on High-P metamorphism
dc.typeJournal article
local.description.notesImported from ARIES
local.description.refereedYes
local.identifier.citationvolume222
dc.date.issued2004
local.identifier.absfor040203 - Isotope Geochemistry
local.identifier.absfor040304 - Igneous and Metamorphic Petrology
local.identifier.absfor040313 - Tectonics
local.identifier.ariespublicationMigratedxPub15852
local.type.statusPublished Version
local.contributor.affiliationGray, Derek, McGill University
local.contributor.affiliationHand, Martin, University of Adelaide
local.contributor.affiliationMawby, Jo, University of Adelaide
local.contributor.affiliationArmstrong, Richard, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationMiller, Jodie, University of Stellenbosch
local.contributor.affiliationGregory, Robert T, University of Melbourne
local.description.embargo2037-12-31
local.bibliographicCitation.startpage407
local.bibliographicCitation.lastpage422
local.identifier.doi10.1016/j.epsl.2004.03.016
dc.date.updated2015-12-12T08:17:21Z
local.identifier.scopusID2-s2.0-2442663167
CollectionsANU Research Publications

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