| Abstract Submission No. | ABS-4.1-0145 |
| Title of Abstract | 3D Magnetic inversion for deep subsurface structure near the confluence point of the Ganga & Yamuna rivers |
| Authors | Sukant Oraon*, Ravi P Mishra, Ved P Maurya, Akhil Mishra, S Chandra |
| Organisation | CSIR-National Geophysical Research Institute, Hyderabad 500007 |
| Address | H.no. 93 Dahutoli, Dhurwa Ranchi, Jharkhand, India Pincode: 834004 E-mail: sonuoraoniitb10@gmail.com |
| Country | India |
| Presentation | Oral |
| Abstract | In this study, we focused on 3D magnetic inversion to investigate the deep subsurface structures in the Ganga-Yamuna Doab region, with the objectives of understanding aquifer heterogeneities and groundwater dynamics. As transient time domain electromagnetic data (TEM) is sensitive to shallow depth ranges and can map water-bearing sediments effectively, whereas magnetic data is more suitable for imaging deeper causative magnetic sources such as basement, fault, contacts and joints, etc. Airborne magnetic data were acquired with varied line spacings (500-1500 m) over the Ganga Yamuna Doab region. For 3D magnetic Inversion, we used SimPEG, an open-source platform, to generate 3D susceptibility models from unfiltered data as well as high-pass filtered datasets with cutoff wavelengths of 50 km and 20 km. The model obtained with data filtered with a 20 km cut-off wavelength was selected because it emphasised the response from causative sources at the target depth of 5 km. To interpret the inversion, we made magnetic susceptibility slices at different depths ( 1 km, 2 km and 5 km) and cross-sections along the flight directions, using the Pyvista and Paraview software. To delineate the lineaments, deep faults, geological contacts, etc, the total horizontal gradient for the susceptibility model has been computed at different depths. The peaks of total horizontal gradient are picked up to highlight the trend for zones of maximum contrast. Based on trend lines, we have identified the lineaments, deep faults and geological contacts in the study area. Such structural features are significant because they allow deep percolation and storage of groundwater and provide potential pathways to understand hydrodynamics on a regional scale. The final 3D susceptibility model may be integrated with TEM to provide a hydrogeological model (with both shallow and deep geological/structural controls) to better understand the deep aquifer systems in the Ganga Yamuna Doab region. |
| Keywords | Airborne Magnetics, 3D inversion, susceptibility, deep structure, confluence. |