Utilization of Landsat 8 OLI Image Data for Detection of Alteration Zones and Geological Mapping. Case Study: Fodikwan Area, Redsea State, Sudan.

Abstract

Abstract This study was carried out in Red Sea state in the area around Fodikwan Village west of Osief and investigated by means of remote sensing and Geographic Information System (GIS).The study area represents part of the Red Sea Hills, which belong to the Nubian Shield of the northeastern Africa. The Arabian-Nubian Shield is known to be one of the major Orogenic belts formed during the Neoproterozoic assembly of the Greater Gondwana (Stern, 1994). the Arabian-Nubian Shield was formed by the accretion of several intra-oceanic microplates , due to the subduction related processes and collision tectonics during the late Precambrian to early Proterozoic Pan- African events between 950 and 500 Ma. Geologically the study area include units of Grey Granite, Meta-sedimentary Rocks (Greywacke) Meta-volcanosedimentary Rocks (Meta Granodiorite, Meta-andesite, Ignimbrite, Rhyolite), Talc, Post Organic Granite, and Superficial Deposits ordered from oldest up to youngest unit. Digital image processing was conducted to enhance the visual interpretation of the Landsat 8 OLI data. These processing are including color composite to generate colored images with bands 3,2,1 respectively to show real color composite of the area , and bands 7,5,2 showing composite image with linear and deceleration stretched to apply more enhancement of the images. This enhancement helped to discriminate lithological units and morphological features of the area. Band ratios techniques were used in order to give geologically information with ratios combination of sultan images (6/7, 6/2 and 6/5*4/5), Abrams images (6/7, 6/5 and 4/2) and Sabin Images (4/2, 6/7, 4/6). These combinations gives strong and well- enhanced results of clear discrimination of the areas units. Also principal components analysis have been done using six bands as well as four selected bands to generate feature oriented image of these analysis witch use minerals if iron oxide an hydroxyl bearing bands with statistics of eigenvector of each . Mineralized zones at the study area where detected using these processing. All the above processing techniques along with integration of ArcMap were used to draw geological map of the area at scale 1:100000 representing lithological units with structural elements and morphological features.