Petrochemical Studies on Chromites from Sinduvalli, Karnataka, India

Mineralogical and chemical studies of chromite deposits of Sinduvalli ultramafic body, Mysore District, show definite evidence of layering and other crystal settling processes. Stretching of occluded olivines, chain structures in chromite and rotation of chromite layers indicate their participation in the deformational episodes which affected the area. Structure and chemistry of chromites classify the host ultramafics as belonging to stratiform type. Presence of gabbroic anorthosites confirms this and indicates that they represent layered complexes characterizing the Sargur high-grade terrain.

The presence of recrystallised orthopyroxenes and development of chrome amphibole indicate their formation under metamorphic conditions. Olivine-spinel geothermometry suggests re-equilibration at sub-solidus temperatures during high grade metamorphism. The formation of 'Ferritchromit' zones is connected to magnesite formation.