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

D.R. Gray, M. Hand, J. Mawby, R.A. Armstrong, John Miller, R.T. Gregory

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    34 Citations (Scopus)

    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 (
    Original languageEnglish
    Pages (from-to)407-422
    JournalEarth and Planetary Science Letters
    Volume222
    Issue number2
    DOIs
    Publication statusPublished - 2004

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