Basement surface interaction in north-west Bengal Basin

The northwest Bengal Basin is one of the least explored areas where the basement surface interaction is still controversial. We analyze satellite images, bouguer anomaly data and construct a long-term tectonic model. Satellite images reveal significant spatial changes in the uplifted Barind tract and its surrounding low-lying subsided floodplains. The regional and residual gravity anomalies exhibit an association with the surface geologic structures. For example, the uplifted Barind tract areas are located on top of the gravity highs represent crustal horst. On the other hand, low-lying flood plains and faults are located on the gravity lows represent graben. To explore the relationship between the surface and basement structures, we construct a geodynamic model. We find that the model produces conjugate thrust faults beneath the horst. With time the faults reach the surface and push the horst block upward. We do not see such noticeable upliftment in the graben structures. Finally, we conclude that the uplifted surface structures and the surrounding low-lying flood plains may be produced by the regional compression and have a relationship with existing basement structures.