Characterization of ASTER spectral bands for mapping of Pyrophyllite of hydrothermal alteration zones in and around Tikamgarh, Madhya Pradesh.

The Bundelkhand Craton located in the northern part of the Indian Shield had been subjected to polyphase deformation and polyphase metamorphism in several episodes from Archaean to early Proterozoic times. The Craton comprises pyrophyllite-diaspore deposits mainly along the NE-SW trending shear system indicated by prominent quartz reefs where intense silicification has taken place during hydrothermal alteration. In the present study, the ASTER images were analyzed to demarcate the pyrophyllite deposits in the Tikamgarh based on the spectral characteristics of pyrophyllite with a strong absorption peak of 2.165 μm. The band ratio, band math images from ASTER data and the sub-pixel classifications of pyrophyllite were adopted by using Linear Spectral Unmixing (LSU) and Mixture Tuned Matched Filtering (MTMF) algorithm. The combination of these methods could detect the mineable pyrophyllite deposits more accurately. This approach along with field geological observations, petrological and chemical analyses could differentiate the high-grade and low-grade pyrophyllite more easily. It could provide information regarding the probable pyrophyllite mining activity. This research has also aided knowledge to investigate similar types of deposits anywhere in the world. [ABSTRACT FROM AUTHOR]