Surface and Crustal Study Based on Digital Elevation Modeling and 2-D Gravity Forward Modeling in Thandiani to Boi Areas of Hazara Region, Pakistan

Abstract

Gravity data indicates that there is a regular relation between crustal structure, crustal density (composition), and surface ascension. In order to delineate surface and subsurface geological structure features, and to calculate the thickness variation of the crust and sedimentary/metasedimentary wedges, integrated approach of Geographic Information System (GIS) i.e. digital elevation models (DEMs) and two-dimensional forward modeling of gravity data were utilized, which provide the best results for the primary objectives. Tectonically, the study area lies in the Lesser Himalayas as well as to an extent in the sub-Himalaya, more concretely in the western limb of Hazara Kashmir Syntaxis. Topographic data was accumulated in XYZ coordinates utilizing point heights method, and DEMs generation, manipulation, interpretation, and visualization process were directed to surfer-15 and ArcGIS software. Determinately the visualization of surface geological structure in the form of DEMs were proposed. The gravity stations in single contour mode have been quantified by using Scintrex CG-5 gravity meter. The collected gravity data was processed by standardizing corrections, two-dimensional forward modeling along with gravity profile were utilized and bouguer anomaly map and gravity model was computed utilizing bouguer density of 2.4 g/cm3, where the subsurface structures are demarcated by the bouguer anomaly and gravity model. In summary this research has allowed the validation of surface and subsurface geological structure visualization. Digital elevation models provide a defensive prediction of the geological structure of the regional surface. The gravity model demarcated a series of stratigraphic units with density boundaries within the basement. The gravity model also suggests that the thickness of sedimentary/metasedimentary wedge in Thandiani area is 11.48 km and in Boi area, the thickness elongates to about 14.43 km. The total thickness of crust in Thandiani and Boi area is 49.53 km and 52.43 km respectively.