INTRUSIVE VEIN OF PELITIC MIGMATITE IN MASSIF-TYPE CHARNOCKITE: IMPLICATIONS FOR A SECOND UHT EVENT, IN THE ONGOLE DOMAIN OF THE EASTERN GHATS BELT

The chronological relation between the two major components of the Eastern Ghats Belt, namely, massif-type charnockite and khondalite, is uncertain, particularly because no unequivocal field evidence is available in published literature to date. However, one recent work suggested that charnockitic magmas were emplaced at the peak of Ultra-high temperature metamorphism in the metapelites in the Eastern Ghats Province. From the Ongole domain a discordant relation between the pervasive gneissosity in the two lithotypes is documented here. Most importantly, intrusive vein of pelitic migmatite in massif-type charnockite implies a later thermal event, particularly vis-a-vis massif-type charnockite (dated as 1.6 Ga) of the area. In the Ongole domain of the Eastern Ghats Belt, UHT metamorphic event was earlier reported around ca. 1.7 Ga. Thus the pelitic migmatite vein at Naraseraopet could arguably be described as a second UHT metamorphic event (Grenvillian?) in the Ongole domain.