Petrology and geochemistry of amphibolites and greenschists from the metamorphic sole of the Muslim Bagh ophiolite (Pakistan): implications for protolith and ophiolite emplacement
MetadataShow full item record
© 2014, Saudi Society for Geosciences. Metamorphic sole rocks are exposed beneath both the Jang Tor Ghar Massif (JTGM) and Saplai Tor Ghar Massif (STGM) of the Muslim Bagh ophiolite. The sole rocks comprise the basal mylonitic part of the ophiolite peridotites and the sub-ophiolitic metamorphic rock series showing inverted metamorphic gradients. The latter mainly consist of garnetiferous amphibolites, amphibolites and greenschists. The mineralogy of the amphibolites (hornblende + plagioclase ± quartz ± biotite ± epidote ± apatite ± opaque) and garnet amphibolites in the metamorphic sole rocks of the Muslim Bagh ophiolite is similar except for the presence of garnet in the latter. Greenschists contain minerals such as chlorite + plagioclase + epidote ± actinolite ± quartz ± opaques. The mineral assemblages of these rocks suggest that they are meta-basites. Geochemical analyses indicate that the garnetiferous amphibolites are metamorphosed tholeiitic to alkaline basalts, akin to ocean island basalts (OIB). By contrast, the amphibolites and greenschists have geochemical signatures akin to mid-oceanic ridge basalts (MORB). Basalts of OIB type are also found in the hyaloclastite-mudstone unit (Bhm), while the MORB-type basalts are found in the basalt-chert unit (Bbc) of Bagh complex underlying the ophiolite nappe. Here, we interpret an early stage OIB-type basalt accretion to the base of the obducted plate associated with extrusion of volcanic rocks in the Bhm unit of Bagh complex followed by amphibolite facies metamorphism. During the later stage of the advancing ophiolitic thrust sheet, MORB-like basalts, such as those found in the Bbc unit of the Bagh complex, are underplated and metarmophosed to greenschist facies with subsequent accretion of the entire sequence of the Muslim Bagh ophiolite and the Bagh complex onto the Indian Platform sediments.
Showing items related by title, author, creator and subject.
The metamorphic sole of New Caledonia ophiolite: 40Ar/39Ar, U-Pb, and geochemical evidence for subduction inception at a spreading ridgeCluzel, Dominique; Jourdan, Fred; Meffre, Sébastien; Maurizot, Pierre; Lesimple, Stéphane (2012)Amphibolite lenses that locally crop out below the serpentinite sole at the base of the ophiolite of New Caledonia (termed Peridotite Nappe) recrystallized in the high-temperature amphibolite facies and thus sharply ...
De Waele, Bert (2004)The Irumide belt is an elongate crustal province characterised by Mesoproterozoic tectonism and magmatism that stretches over a distance of approximately 900 kilometers from central Zambia to the Zambia-Tanzania border ...
Thermal evolution of an ancient subduction interface revealed by Lu–Hf garnet geochronology, Halilbagi Complex (Anatolia)Pourteau, Amaury; Scherer, E.; Schorn, S.; Bast, R.; Schmidt, A.; Ebert, L. (2018)The thermal structure of subduction zones exerts a major influence on deep-seated mechanical and chemical processes controlling arc magmatism, seismicity, and global element cycles. Accretionary complexes exposed inland ...