Abstract
Extreme thermal condition of metamorphism in continental deep crust is an enigmatic issue. Moreover, the post-peak thermal relaxation history of such orogenic deep crust is also not properly known. In view of this, we have chosen an aluminous granulite from Eastern Ghats, India to study their thermal history and to calculate cooling rate(s). Compositional profile across the interface between garnet-orthopyroxene reveals homogeneous garnet composition yielding near-peak temperature of 930oC, while that across garnet-(Ti-F)biotite yields temperature of 800-875oC with a zoning profile in garnet. Diffusion kinetics modeling of such zoning profile yields anomalously high cooling rate of ~12-25oC/ky at 875oC.
