Zircon ages of late Palaeoproterozoic (ca. 1.72–1.70 Ga) extension-related granitoids in NE Rajasthan, India: Regional and tectonic significance

• Published in: Gondwana research 2011-06, Vol.19 (4), p.1040-1053
• Main Authors: Kaur, Parampreet, Chaudhri, Naveen, Raczek, I., Kröner, A., Hofmann, A.W., Okrusch, M.
• Format: Article
• Language: English
• Subjects: A-type granites; Aravalli orogen; Columbia supercontinent; late Palaeoproterozoic; Zircon geochronology
• ISSN: 1342-937X; 1878-0571
• DOI: 10.1016/j.gr.2010.09.009

The Khetri region forms a late Palaeoproterozoic igneous–metamorphic complex in NE Rajasthan, India. Seven granitoid plutons of the Khetri complex have been studied for zircon U–Pb and Pb–Pb dating along with whole-rock and Nd–Sr isotope geochemistry to provide new constraints on the Palaeoproterozoic magmatic activity in the Aravalli orogen of northwestern India. Most intrusives show evidence of moderate to extreme albitisation forming microcline–albite granite and albite granite, respectively. The rocks are metaluminous to weakly peraluminous, largely ferroan and intraplate A-type granites. The U–Pb zircon ages for four plutons cover a time span of 1732–1682 Ma, whereas Pb–Pb zircon evaporation data for three intrusives indicate minimum emplacement ages between 1671 and 1537 Ma. The Nd–Sr isotopic systematics suggest the involvement of Neoarchaean to Palaeoproterozoic crustal components in the petrogenesis of these granitoids. A regional survey of late Palaeoproterozoic ages in the Aravalli orogen provides evidence for a geographically widespread extension-related event in the northwestern Indian shield about 1720–1700 Ma ago. The record of comparable ages and the magmatic history reported in parts of North America and the North China Craton may indicate the significance of this event for the rift tectonics of the hypothetical supercontinent Columbia. [Display omitted] ► New zircon ages along with whole-rock geochemical and isotope data are presented from seven granitoid plutons of the Khetri complex, NE Rajasthan, India. ► The ca. 1720–1700 Ma ages obtained from the Aravalli orogen when compared with rocks of similar age and similar tectonic setting in North America and North China Craton suggest a widespread extensional-related event in these parts of the globe. ► The 1700 Ma ages are correlated to the rifting history of the supercontinent Columbia.