Browsing by Author "Ahmad Abir, Ismail 1988-"
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Item Applications of InSAR and 2D Seismic Interpretation for Salt Tectonic Studies in the Salt Range and Potwar Plateau Region, Northern Pakistan(2012-12) Ahmad Abir, Ismail 1988-; Khan, Shuhab D.; Bendick, Rebecca O.; Glennie, Craig L.; Van Wijk, Jolante W.Salt tectonics in Northern Pakistan affects the geological structures and the seismology of the area. Salt layers are important in influencing the deformation style of geological structures. The difference in deformation intensity between the Potwar Plateau-Salt Range and the Kohat Plateau-Surghar Range systems is attributed to the presence of a Pre-Cambrian salt layer. Overburden will translate efficiently on the ductile salt detachment and will result in low internal deformation, which is evident in the Potwar Plateau-Salt Range system. In this system, the salt layers act as a lubricant between the overlying sedimentary layers and the basement rocks. In contrast, the Kohat Plateau-Surghar Range system has high internal deformation. This could be due to the absence or the thinning of the salt layers which causes increase friction between the overburden and the basement rocks. This study is an attempt to investigate the role of salt in the geological deformation of the Salt Range-Potwar Plateau using InSAR, 2-D seismic interpretations, and geomorphic index calculations. 3-pass interferometry was done using 8 ALOS PALSAR scenes, in order to create a surface displacement map with two years temporal difference. The InSAR and geomorphic index results suggest that the Salt Range may still be active tectonically and has undergone uplift. Six migrated seismic reflection lines were interpreted showing basement ramps due to normal faults. These ramps are believed to act as transition zones between different roles of salt; salt layer act as a decollement to the north and salt flow is prominent to the south. Furthermore, the results also suggest that differential loading is the main driving force for the salt flowing to the south. However, buoyancy force may play a significant role in the deformation of vi the Salt Range due to the uplift. Moreover, both the salt layer and the geometry of the basement influence the deformation style in this region. This thesis suggests that the Salt Range and Potwar Plateau region is a thin-skinned fold-and-thrust belt due to the wedge shape of the plateau and the salt as the weak detachment layer.Item Integration of Seismic Interpretation with Remote Sensing Techniques to Study the Neotectonics of the Fold-and-Thrust Belts of Northwestern Pakistan(2016-05) Ahmad Abir, Ismail 1988-; Khan, Shuhab D.; Mann, Paul; Li, Aibing; Aziz, GulzarThe fold-and-thrust belts of Pakistan are actively deforming and consequently produced devastating earthquakes which destroyed many lives, infrastructures, and properties over the last century. This work focuses on three fold-and-thrust belts, located along the Main Frontal Thrust; from east to west, the Potwar Plateau, the Bannu Basin, and the Sulaiman Fold Belt. Coupled with these fold belts are curved structures referred to as re-entrants. The Sibi Re-entrant, located adjacent to the Sulaiman Fold Belt, has experienced many earthquakes in comparison to the Tank and Kalabagh Re-entrants. In order to understand the factors that control the formation of these re-entrants and fold belts, radar satellite image processing technique, InSAR (Interferometric Synthetic Aperture Radar), was utilized and integrated with other available data, such as seismic profiles, well logs, gravity, and multi-spectral satellite imagery mapping. The integration of InSAR using ten PALSAR images and seismic data shows that the Potwar Plateau is still tectonically active with areas uplifting up to 15 mm/yr. Based on seismic and well data, salt acts as the main detachment layer displaying thin-skinned deformation. In addition, salt tectonics is observed to be concentrated near the Main Frontal Thrust, where the overlying rocks are the weakest. The Tank and Kalabagh Re-entrants were interpreted as ‘basin-controlled’ curves with the presence and the extent of salt controlling the shape of re-entrants. Differential movement between areas containing salt and areas with no/lack of salt resulted in the formation of right-lateral strike slip faults (Pezu-Bhittani and Kalabagh faults) and in consequence their respective re-entrants. In contrast, there is no clear indication of a major right-lateral strike-slip fault forming the Sibi Re-entrant. InSAR processing of 34 Envisat satellite images showed that the western Sulaiman belt experienced a complex deformation with a mixture of different lateral motions. Satellite mapping of active structures in this region using Landsat 8 and Sentinel 2 images suggested a right-lateral shear zone with evidence of ‘bookshelf faulting’, indicating a distribution of deformation across the zone rather than along a strike-slip fault. The difference is attributed to the shape of the Katawaz basin and the weak detachment sliding over thick sediments.