Geochemical and geochronological data from charnockites and anorthosites from India's Kodaikanal-Palani Massif, Southern Granulite Terrain, India

The Kodaikanal–Palani Massif is an important component of India’sSouthern Granulite Terrain; understanding the tectonic history of its rocks lendsconsiderable insight into its role within South India. The massif is located southof the Palghat Cauvery Shear Zone (PCSZ). Compilations of available geochronologicand geochemical information from charnockites north and south of the PCSZshow these rocks largely differ in age, with northern samples recording Archaeancrystallization events, whereas those to the south yielding Cambro-Ordovician andNeoproterozoic ages. The Kodaikanal–Palani charnockitic rocks contain monazitegrains that fall within the Cambro-Ordovician timescale. The Oddanchatramanorthosite, located along the northern boundary of the Kodaikanal–Palani Massif,contains zircon grains that record mid-Neoproterozoic to Cambro-Ordoviciancrystallization ages. This anorthosite differs in texture and composition dependingon location, that may be the result of its multi-stage metamorphic and/or intrusionhistory. Charnockitic rocks north and south of the PCSZ also differ geochemically.For example, north of the PCSZ, these rocks become more calcic with increasingSiO2 contents, whereas those to the south become alkali-calcic