Building 3D Geomorphological Models from Legacy Resistivity Data in the Kabul River Valley, Pakistan

Through the application of modern geostatistical analysis and inversion techniques drawn from contemporary seismic interpretation methods a number of 1D resistivity data have been re-modeled and visualized in 3D space. The resultant model extends the original interpretation of the data to depict alluvium layers as lithological and structural units within the bedrock. By tuning the variogram parameters used in this approach it is possible to visualize the individual lithofacies and geomorphological features in the subsurface rock units. In this study an electrical resistivity data set collected in the 1980’s as part of a groundwater study in an area of the Peshawar basin of Pakistan has been re-examined. Limited borehole log data have been combined with local outcrop information to calibrate the data.

The Himalayan orogeny has uplifted and generated significant faulting in the bedrock of the area resulting in the formation of several clay-filled depressions. Paleo-streams have reworked the clays and the resultant sediments have been deposited as prograding fan shaped bodies and lacustrine deposits with inter-layered sand-gravel and clay-silt facies. The Naranji area aquifer has thus formed as a result of local tectonic activity with fluvial erosion and deposition and is characterized by coarse sediments with high electrical resistivities.