MINERAL-COMPOSITION AND ITS BEARING ON DEPOSITIONAL HISTORY OF BANDEDIRON-FORMATION OF KUDREMUKH SCHIST BELT, KARNATAKA

The iron-formations of Kudremukh mainly contain magnetite, recrystalli zed chert, grunerite-cummingtonite (X(Mg) 0.21 to 0.33), hornblende, b iotite along with minor amounts of ankerite (X(Mg) 0.30 to 0.52), calc ite (X(Mg) 0.06 to 0.22), chamosite and pyrite. Chamosite, a rare reli ct mineral, was probably formed by reaction between high Al-clay and F e. Magnetite was formed during metamorphism. Along with the precipitat ion of alternating layers rich in silica and iron, clayey material in the form of montmorillonite, illite and/or glauconite along with Fe-Mg carbonates were also deposited, which after metamorphism (430-520 deg rees C) gave rise to the present mineralogy.