Electron microprobe dating of monazites from an ultrahigh-temperature granulite in Southern India: Implications for the timing of Gondwana assembly

Abstract

We report here monazite geochronology on a newly discovered high pressure (HP) and ultrahigh-temperature (UHT) granulite locality at Thoppur within the Palghat-Cauvery Shear Zone system in southern India. In situ dating of monazites associated with the UHT minerals using electron probe technique yielded PbO vs. ThO₂^* apparent isochron age of 544 ± 5 Ma. This is the first study from southern India where older monazite cores or complex age patterns are virtually absent, and all the monazite population in the studied samples crystallized/recrystallized during a single thermal maximum which we correlate with the timing of extreme crustal metamorphism during the final assembly of the Gondwana supercontinent.