At 750 Ma India was part of a lar
ger fra
gment of eastern Gondwana blocks that included the Seychelles-Mauritia, Mada
gascar, Sri Lanka and the Enderby Land-Prydz Bay re
gion of East Antarctica. Subduction of the Mozambique Ocean beneath Seychelles-Mauritia, northern Mada
gascar and northwestern India formed a len
gthy continental arc that remained active durin
g the formation of Gondwana. Paleoma
gnetic data from the Malani rhyolites and associated dykes provide a robust paleoma
gnetic pole constrainin
g India's position at this time. The rhyolitic and
granitic rocks associated with the Malani I
gneous Suite (MIS) have robust a
ge constraints; however, the a
ges of the mafic dykes were inferred solely on the basis of similarity in paleoma
gnetic directions to the rhyolitic units. Here we present new
geochronolo
gical data from the Malani mafic dykes that yield a
minimum age of 704 Ma. The
207Pb/
206Pb a
ges obtained for the dykes are less-likely to be affected by Pb-loss and yield a more reliable estimate for the a
ge of the mafic dykes of ~ 750 Ma. We ar
gue that intrusion of these mafic (and minor felsic) dykes represents the final pulse of MIS ma
gmatism.
Many of the granitic rocks in the region are reported as 鈥榰nclassified鈥?due to limited geochemical data and/or geochronological ages. Some of these 鈥榰nclassified鈥?granites are intruded by the mafic dykes sampled in this study near the town of Bilara. The granites yielded zircon core ages of ~ 1100 Ma with younger rims averaging ~ 1020 Ma. We argue that this provides further evidence for a significant orogenic event ~ 1000 Ma that may relate to the collision of the Marwar block with the Banded Gneiss Complex/Bundelkhand craton in north-central India. Other ~ 1000 Ma orogenesis is also known along the Central Indian Tectonic Zone (CITZ) and the Eastern Ghats Mobile Belt. Globally, this same time interval is thought to represent the amalgamation of the supercontinent Rodinia and may also have resulted in the closure of the major 鈥淧urana鈥?basins in India.