SUBSURFACE GEOLOGICAL MODEELING OF MISS KESWAL AREA POTWAR PLATEAU, UPPER INDUS BASIN, PAKISTAN

Abstract

Missa keswal is situated in an active foreland fold and thrust belt of Himalaya orogeny on eastern side of Potwar Plateau of Pakistan. The present work is based on 2D seismic and well logs data of the area with the principal goal to find out the subsurface structure model and crustal shortening. On the base of synthetic seismogram and well ties, three major horizon tops; Chorgali, Patala, and Kewra Sandstone were marked. Besides, one normal fault in their basement and seven major reverse faults were marked and categorized in the sedimentary cover sequence of the Missa Keswal area on seismic section. These three horizons were identified on time contour map and later depth contour map by converting time domain into depth domain through the help of interval velocity. These indicate the presence of pop-up anticline structure present in the subsurface contained by reverse faults from both sides. 2D modeling of the interpreted seismic section revealed, that Missa Keswal area lies in a compressional regime characterized by pop-up anticline structure having oriented axis in NE-SW direction, which is bounded by reverse faults from both sides. 2D seismic interpretation confirmed that the compressional tectonic is the main reason of deformation in this area and their main structure was developed into two main stages. Initially, normal faulting occurred in the basement and later was followed by reverse faulting in the sedimentary cover sequence. This led to crustal shortening in the area. One major reverse fault lies on the SE limb while, other reverse faults on the NW limb. Besides, one normal fault is also present in the basement, which represents splitting and rifting of Pangea in Jurassic time. The models made based on the geology and seismic sections of the area indicate that the area is highly deformed due to Himalayan Orogeny and crustal shortening occurred and pop-up anticline structure developed that is bounded by reverse faults on both SE and NW limbs.