REFLECTANCE SPECTROSCOPY AND HYPERSPECTRAL REMOTE SENSING FOR MAPPING OPHIOLITES IN WESTERN PAKISTAN

In geological history, the collision of India with Asia is a great event, on which many researchers have spent their scientific careers; however there are still many unsolved mysteries. Ophiolites are generally found in suture zones and can provide important information on tectonic evolution and age of initial collision. The Bela Ophiolite (BO) and Muslim Bagh Ophiolite (MBO) in the western Pakistan are located along the westernmost India-Asia boundary. There are 3 hypotheses for their origin, Obduction of ocean floor for BO and MBO, suprasubduction-zone and Leaky transform for BO. BO and MBO are very important, however they are least studied mainly because of their remote location.

Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) data over BO and MBO are processed with several image-processing methods. ASTER is a multi-spectral imaging system launched on Terra Satellite and it has14 bands in different parts of the electromagnetic spectrum: 3 in the visible and near infrared, 6 in short wave infrared and 5 in the thermal infrared. All the major lithological units including harzburgites, gabbros, sheeted dikes and pillow lavas of BO and MBO can be mapped using principal component analysis and minimum noise fraction analysis of ASTER data. ASTER is very useful in mapping the BO and MBO, however some dikes of different composition i.e., diabase and pyroxenite etc. can't be differentiated in MBO. Therefore, Hyperion hypspectral data that has much higher spectral resolution (220 bands) was chosen to address this problem. At first reflectance spectroscopy data of MBO rocks was obtained in laboratory using analytical spectral devices (ASD) spectroradiometer, and then it was used to classify Hyperion hyperspectral image using Spectral Angle Mapper (SAM) technique. SAM classification not only discriminated different dikes but also showed detailed internal structures of the major lithological units. This research provides basis for future work which will involve detailed geochemical and isotopic studies for better understanding collision of India and Asia in western Pakistan.