Exploration Of Hydrothermally Altered Mineral Deposits By Using Remote Sensing Data In DIR LOWER,KP,PAKISTAN

For the current research work the western part of Kohistan Island Arc has been selected in the vicinity of Dir area,Khyber Pakhtunkhwa Pakistan.The Kohistan Island Arc experiences the different tectonic episodes and magmatism which results in the alteration and mineralization in the rocks of Kohistan Island Arc.The study area comprises the amphibolites and dioritic rocks.This study was carried out to demarcate the mineral potential zones in hydrothermally altered rocks with the presence of field observation,spectrometry,petrography and remote sensing analysis.The alteration and mineralization in the study area is mostly associated with dioritic and amphibolitic rocks.These rocks have been analysed with the help of hand lens in the field observation followed by the petrographic analysis.The altered minerals in the host rocks have been confirmed with the help of petrographic analysis which includes sericite,chlorite and epidote.The spectra of host rock were measured to analyse the major minerals.Various spectral signatures have been observed from the spectrometry which were then compared and confirmed with the USGS typical spectral signatures of minerals.Landsat-7,Landsat-8,and Sentinel-2B data have been processed in ERDAS and Arc GIS to delineate the altered zone of the study area.Various remote sensing algorithms(band composition,principal component analysis and band ratio)were used to get the required results,and promising results have been achieved from the principal component analysis techniques comparing to the other algorithms.Band ratio composite(3/1,5/6,5/4)for Landsat-7,(4/2,6/7,6/5)for Landsat-8 and(4/2,11/12,8/11)were used for Sentinel-2B data to highlight the zones of alteration but failed to get the required information.Principal component analysis and false colour composite were found to be beneficial in getting required information.Principal component analysis of band combination 1,3,4,5 and 1,4,5,7 for Landsat-7 and 2,4,5,6 and 2,5,6,7 for Landsat-8 and 2,4,8,11 and 2,8,11,12 for Sentinel-2B were found effective for an alteration zone detection.Colour composite combination 4,7,2 for Landsat-7,4,6,2 and 5,6,7 for Landsat-8 data were found useful in alteration zone targeting.The current alteration zones marked by the remote sensing data match location of known active mines in the study area.It is confirmed that the current research work suggest that the central and western part of the study area bears the good potential in term of mineral deposits.