Integrated geophysical analysis of Rangpur Saddle: insights on tectonics and magnetic mineral potential of north-western Bangladesh

Abstract

The northwestern region of Bangladesh holds untapped potential for magnetic mineral deposits at shallow depths. Unlike much of Bangladesh, characterized by thick sediments of the Bengal Basin, this area is an extension of the Indian Shield, often referred to as the Stable Platform. It is also geologically distinct, hosting structures related to the breakup of Pangea. The geology and tectonics of this region have remained largely understudied. To address this gap, this study integrates gravity, magnetic, seismic, and drilling data to investigate the subsurface structure and evaluate the resource potential of the area. We utilize advanced filtering and modeling techniques, including tilt derivatives and horizontal gradient methods, to understand the tectonic framework and geometry of the subsurface structures. Our spatial analysis, using multiple geophysical datasets, reveals dipolar magnetic anomalies, which we attribute to gabbroic intrusions along extensional faults that define the region's horst and graben structures. To validate our interpretations, we developed an integrated 2-D subsurface model that aligns with the observed geophysical data. However, the study is limited by the availability of high-resolution seismic data and the sparse distribution of drilling locations, which may affect the precision of our subsurface characterization. Our findings provide crucial insights into the tectonic evolution of the stable platform and underscore the economic potential of the Rangpur Saddle, the shallowest part of the stable platform, for mineral exploration. These insights pave the way for further exploration and development initiatives focused on uncovering the mineral wealth of this underexplored region.