Textural developments in chromite deforming under eclogite-facies conditions from the Neoarchaean Sittampundi anorthosite complex, southern India


Biswajit Ghosh, Department of Geology, University of Calcutta, 35, Ballygunge Circular Road, Kolkata 700019, India. E-mail: bghosh_geol@hotmail.com


We describe the textural evolution of chromites from the Neoarchaean Sittampundi anorthosite complex in southern India. A series of micro-structural developments in chromites with increasing temperature is recorded. The intracrystalline deformation started with a high strain rate at elevated temperature. At higher temperature, crystal plastic deformation like recovery/recrystallization was initiated developing subgrains in chromites. Diffusion processes played a major role during deformation as documented from grain boundary geometry of chromites with adjacent silicates, distribution of silicate inclusions in the host chromites as well as in the new grains, and the development of sector Al–Cr zoning. At the highest temperatures, diffusion might have overstepped the recovery. After deformation stopped, static recrystallization by grain boundary area reduction resulted in grain growth. A high-strain steady-state, heterogeneous deformation, as evidenced from the chromite micro-structures is suggested for the Sittampundi chromites. Copyright © 2011 John Wiley & Sons, Ltd.