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U–Pb zircon geochronology of ferrodiorites and quartz diorites from the Turkel Anorthosite Complex: a Neoarchaean convergent margin in eastern India



The Turkel anorthosite Complex (TAC) in the Eastern Ghats Belt in India is composed of anorthosites and leuconorites at the centre and ferrodiorites and quartz diorites at the periphery. Here we report whole-rock geochemistry, and zircon U–Pb data and REE geochemistry from a co-spatial ferrodiorite and two quartz diorites from the TAC. The diorites have low abundance of High Field Strength Elements (HFSE) and REE, exhibit a flat chondrite-normalized pattern with slight LREE enrichment and negligible or no Eu anomaly. Our results show weighted mean 207Pb/206Pb ages of 2433 ± 33 Ma for the ferrodiorite. Two quartz diorite samples from Turkel yield mean207Pb/206Pb ages of 2419 ± 32 Ma and 2505 ± 31 Ma. The zircons from all the analysed samples show high REE contents, prominent HREE enrichment and a conspicuous positive Eu anomaly, suggesting a common magmatic source. The prominent Neoarchaean to early Palaeoproterozoic magmatic ages from the anorthosite complex deviate from the late Neoproterozoic ages reported from other anorthosite suites in the Eastern Ghats Belt, and suggest an active convergent margin along SE India during Archaean–Proterozoic transition. Copyright © 2014 John Wiley & Sons, Ltd.