Sarkar, T. and Schenk, Volker (2016) Early Mesoproterozoic (1.6-1.5 Ga) granulite facies events in the Ongole domain: geodynamic significance and global correlation. Journal of Metamorphic Geology, 34 (8). pp. 765-784. DOI 10.1111/jmg.12207.

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Abstract

The late Palaeoproterozoic to early Mesoproterozoic Ongole domain of the Eastern Ghats Belt in southeastern India is composed of a suite of charnoenderbites with enclaves of metapelitic and mafic granulites. Geochemical data for all meta-igneous rocks are typical for continental magmatic arc suites. The rocks preserve mineral assemblages and reaction textures indicating two separate metamorphic events: an initial counter-clockwise medium-pressure ultrahigh temperature (MP-UHT) event (>900 degrees C at 6.5-7.0 kbar), attributed to the magmatic accretion of the arc, which was followed by a clockwise HP-MT event (similar to 700 degrees C at 9 kbar), attributed to its tectonic crustal thickening. Zircon dating of charnoenderbites yield magmatic crystallization ages between 1.75 and 1.70 Ga and metamorphic ages between 1.62 and 1.60 Ga. Syn-metamorphic enderbites yield magmatic and metamorphic zircon ages of c. 1.60 Ga, overlapping with all other metamorphic rim ages. In contrast, texturally controlled monazite dating of two chemically distinct monazite generations reveals two metamorphic events at c. 1.62 and c. 1.54 Ga. These data suggest that the Ongole domain was formed as a magmatic arc during the Palaeoproterozoic (c. 1.75-1.70 Ga), and subsequently experienced UHT metamorphism accompanied by syn-metamorphic intrusions at c. 1.60 Ga, suggesting magmatic underplating as the metamorphic heat source. The subsequent crustal thickening at c. 1.54 Ga was due to the collision of the Ongole magmatic arc with the Indian craton. The UHT metamorphism and the related orogenic processes of the Ongole domain fall into the assumed late Palaeoproterozoic to late Mesoproterozoic 'orogenic and UHT time gap' (1.8-1.1 Ga) regarded by some studies as an orogenic quiescent period after the formation of the Palaeoproterozoic supercontinent known as Columbia or Nuna at c. 2.1-1.8 Ga. Coeval orogenic processes at c. 1.7-1.5 Ga occurring along accretionary margins in different fragments of Columbia (India, Australia, Antarctica and southwest Africa) indicate a protracted formation of this supercontinent.

Document Type:	Article
Additional Information:	Times Cited: 0 Sarkar, T. Schenk, V. Si
Keywords:	Columbia supercontinent Eastern Ghats Belt magmatic arc Ongole domain ultrahigh‐temperature metamorphism
Research affiliation:	Kiel University OceanRep > The Future Ocean - Cluster of Excellence
Refereed:	Yes
Open Access Journal?:	No
Publisher:	John Wiley & Sons: Blackwell Publishing
Projects:	Future Ocean
Date Deposited:	27 Feb 2017 08:35
Last Modified:	24 Sep 2019 00:08
URI:	https://oceanrep.geomar.de/id/eprint/36298

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