The Eastern Ghats Belt is a polycyclic granulite terrain along the east coast of India whose western boundary is marked by a shear zone along which the granulites are thrusted over the cratonic units of the Indian shield, and its northern margin is marked by the presence of a number of fault-bounded blocks. Recent work has convincingly brought out that there are domains within the belt having different evolutionary histories. The segment south of the Godavari Rift went through a high grade thermo-tectonic event at ~1.6-1.7 Ga. North of the Godavari Rift in a narrow zone along the western boundary the last high-grade metamorphic event is of late Archaean age. A series of alkaline plutons along the western boundary zone testifies to a rifting episode at ~1.3-1.5 Ga. In the major part of the EGB the metamorphism is broadly of Grenvillian age, with two major thermo-tectonic pulses at ~1.1-1.2 Ga and ~0.95-1.0 Ga. But high grade conditions persisted for a long period and younger thermal events of ~0.65 Ga to ~0.80 Ga are locally recorded. There are differences in the tectonometamorphic histories of different domains, but the tectonic significance of these differences remains uncertain. Pan-African (0.50-0.55) thermal overprints are common and become conspicuous along the western boundary zone. The thrusting of the Eastern Ghats granulites in a hot state over the cratons to the west is of Pan-African age. In the Rodinia assembly (~0.9 Ga) the Eastern Ghats and the Rayner-Napier Complexes of Antarctica were contiguous, but the pre-Rodinia configuration of these terrains remains unclear. At ~0.8 Ga during the Rodinia break up Greater India rifted apart from East Antarctica, and only later it docked with Australia-East Antarctica at 530-550 Ma. The continuation of the East Antarctic Pan-African orogenic belts into the Eastern Ghats is yet to be ascertained.

The Lohit Plutonic Complex (LPC) represents Trans-Himalayan magmatic rocks in the easternmost sector of the Himalayan Orogen. It is divided into leucogranite-granodiorite-diorite dominant suite in the NE and the gabbro-diorite-granodiorite-granite-trondhjemite suite in the SE by the Walong Thrust. U-Pb geochronological analyses of euhedral zircon grains from different magmatic phases of LPC reveal episodic magmatism. Zircon U-Pb age of 153.4 ± 1.4 Ma of a garnetiferous granite gneiss suggest that the crustal sourced magmatism was active in Arunachal Trans-Himalaya during the late Jurassic. U-Pb ages of subduction induced magmatic rocks of LPC range between 117 ± 0.6 Ma and 49.5 ± 0.3 Ma. A significant contribution in crustal recycling during the Oligocene-Miocene is evident from crustally derived leucogranites having U-Pb ages ranging from 35.6 ± 0.3 Ma to 30 ± 0.3 Ma. A comparison of the crystallization ages of the Western Trans-Himalayan units with those of eastern Trans-Himalayan units reveals an earlier onset of Tethyan arc magmatism in the eastern sector. The most prominent phase in the eastern sector is during the Late Cretaceous while western and central sector show major activity during the Palaeocene-Eocene.

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