Archaean komatiites from the older schist belt of Kalyadi in western Dharwar craton, Karnataka

The cluster of enclaves at Kalyadi, Hassan district includes ultramafic-maf ic metavolcanic rocks and minor metasedimentary rocks such as chert, cherty quartzite and pelite. Occurrence of pillow and vesicular structures in the ultramafic rocks is being reported for the first time from this area. The avenge composition of the ultramatic rocks is :SiO2 46.05%, TiO2 0.18%, MgO 31.81%, K2O 0.15%, Cr 3409 ppm and Ni 1610 ppm with a CaO/Al2O3 ratio clos e tol. The composition, relict igneous structures and metasedimentary rock association are suggestive of a komatiitic affinity for these rocks, which possibly accumulated under subaqueous conditions.