On bababudanite, a soda-amphibole from the banded ferruginous quartzites of Mysore, India

Abstract

Banded ferruginous quartzites form a conspicuous feature of many of the outcrops of Dharwar schists in Mysore. Because of their much greater hardness than the associated chloritic and hornblendic schists, these quartzites have withstood the action of weathering agencies better, and form prominent hill ranges in the schist belts. One such important range is the Bababudan hills in the Kadur district, comprising some of the highest peaks in the Mysore State, several of which are over 6,000 feet above sea-level. The Bababudan hills are mainly composed of thick beds of haematite and magnetite quartzites which are separated by bands of chloritic and talcose schists. The high angles of dip and the intensely folded nature of these quartzites are evidences of the great disturbances to which these rocks have been subjected. The complicated tectonics of this area have not yet been satisfactorily elucidated, as geological work on these hills is heavily handicapped by the dense jungles infested with wild animals, and the thick soil cap which obscures the disposition and relationship of the rocks. The ferruginous quartzites overlie an epidiorite flow of spilitic affinities. A few dykes of epidiorite, some of which are tourmaline-bearing, have invaded the quartzites.