Two High-Pressure Metamorphic Events in NE Oman: Evidence from40Ar/39Ar Dating and Petrological Data
- 1 November 1992
- journal article
- research article
- Published by University of Chicago Press in The Journal of Geology
- Vol. 100 (6), 731-751
- https://doi.org/10.1086/629625
Abstract
The Saih Hatat tectonic window in NE Oman exposes basement and shelf units that structurally underlie the Semail ophiolite. These units were metamorphosed under high-pressure conditions, as evidenced by the occurrence of lawsonite schists, carpholite-bearing metasediments, blueschists, and eclogites. Conventional K-Ar and 40Ar/39Ar dating of whole rocks and white mica separates from the structurally highest Region I of Saih Hatat and the lowest-grade blueschists of the northern part of the structurally lowest Saih Hatat Region III yield ages of 72-80 Ma. White micas from the high-grade blueschists and eclogites of Region 111, which formed at T > 340-degrees-C, yielded variably discordant age spectra with weighted mean "plateau" ages of 106-111 Ma. The age data, combined with structural and petrological criteria, suggest that many units exposed in Saih Hatat experienced two high-pressure, low temperature (high P/T) metamorphic events. The first, in the Early Cretaceous, was possibly a result of partial subduction of the continental margin beneath a microcontinental fragment of Gondwanaland. The second high P/T event was a result of the Late Cretaceous emplacement of the Semail ophiolite onto the oman continental margin and is characterized by lower temperatures.This publication has 52 references indexed in Scilit:
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