HYPERSPECTRAL AND GEOCHEMICAL SIGNATURES ON CORUNDUM BEARING ROCKS IN PART OF SOUTHERN KARNATAKA, INDIA.

Abstract

Corundum-bearing rocks are associated with metamorphosed mafic rocks in a metamorphic terrain mainly of metasedimentary rocks including gneiss, schist, amphibolite, and minor iron formation. Un oriented corundum crystals surrounded by alkali feldspar halos formed by replacement of the gneiss with the addition of Al and Kin Granulite facies metamorphism of aluminous sediment produced biotite syenite gneiss. Corundum also occurs in cordierite sillimanite schist, gneisses round close pet granite, contact of ultramafics Pegmatite's, Aplite veins disseminated grains in anorthosite kyanite/ staurolite schist, high-grade pelitic schist gravel beds and stream sediments as a placer. It is generally associated with spinel, garnet, kyanite, and high calcium feldspars in plutonic pegmatite and metamorphic rocks. Some of its varieties are oriental amethyst, oriental emerald, oriental topaz, sapphire, ruby (gemstones) and emery (massive). Karnataka state, Dharwar Craton is composed of an active and dynamic geological setting with prospects of many different kinds of economic mineral deposits, including shear zones bearing valuable minerals and gemstones in Precambrian basement rocks. The study area Southern Karnataka covers 20 districts, Field observation using ground truth check, Geochemical analysis data and Hyperspectral data demarcated the Corundum bearing horizons in the study area. Hyperspectral (350-2500nm) is a special type of multispectral imaging scanner which provides a high spectral resolution data to bring out diagnostic features on lithological contacts for better discrimination and rapid demarcated the Corundum bearing rocks across Southern Karnataka. The hyperspectral data on lithological contacts and themes like geomorphology, geology, structure, soil, rocks and minerals will be studied using high-resolution satellite data such as Landsat 8 is a high multispectral imaging radiometer consists of three separate subsystems, Visible near InfraRed (VNIR-15m), Short Wave Infrared (SWIR-30m) and Thermal Infrared (TIR-90m) that have become a potential tool for mapping of precious gemstones in between lithological contacts and mineralized zone. The present study aims to integrate the advent hi-tech tools of hyperspectral Remote Sensing (RS), Geochemical analysis data, EDS analysis data and Geographical Information System (GIS) in demarcating, exploration, scientific surveying of corundum bearing litho units in Precambrian basement rocks of Southern Karnataka.