Geologically constraining India in Columbia: The age, isotopic provenance and geochemistry of the protoliths of the Ongole Domain, Southern Eastern Ghats, India

摘要: Abstract The Ongole Domain in the southern Eastern Ghats Belt of India formed during final stages Columbia amalgamation at ca. 1600 Ma. Yet very little is known about protolith ages, tectonic evolution or geographic affinity region. We present new detrital and igneous U–Pb–Hf zircon data in-situ monazite to further understand this Columbia-forming orogen. Detrital patterns from metasedimentary rocks are dominated by major populations Palaeoproterozoic grains (ca. 2460, 2320, 2260, 2200–2100, 2080–2010, 1980–1920, 1850 1750 Ma), minor Archaean 2850, 2740, 2600 2550 Ma). Combined U–Pb ages Lu–Hf isotopic suggest that sedimentary protoliths were not sourced adjacent Dharwar Craton. Instead they likely derived East Antarctica, possibly same source as parts Proterozoic Australia. Magmatism occurred episodically between 1.64 1.57 Ga Domain, forming felsic orthopyroxene-bearing granitoids. Isotopically, granitoids evolved, producing eHf values − 2 − 12. magmatism interpreted have been reworking crust with only a juvenile input. Metamorphism 1.68 1.60 Ga resulted partial complete resetting grains, well growth metamorphic 1.67 1.63 Ga. In-situ geochronology indicates metamorphism 1.59 Ga. represent part an exotic terrane, which was transferred proto-India late linear accretionary orogenic belt may also included south-west Baltica south-eastern Laurentia. Given isotopic, geological geochemical similarities, proposed terrane be extension Napier Complex, connected Australia (North Australian Craton Gawler Craton).