Subsurface Characterization of Thrust Belts and Synclinal Basins of the Kohima Region, NE India Through Gravity Modelling: Implication for Hydrocarbon Resources

ABSTRACT The Kohima region, comprising the Naga‐Disang imbricated thrust belt of Schuppen, Brahmaputra foreland basin, and the adjoining Assam‐Arakan inner fold belt (IFB) of Indo Burmese ranges, is an important hydrocarbon province with environmental conditions that make it difficult for geophysical investigations. Here, we attempt the subsurface characterization of thrust–fold belts and synclinal basins using Bouguer gravity data. The source parameter imaging technique and tilt angle amplitudes of gravity data are used for estimating basement depths. The computed basement depth varies from 2 to 6 km, and overlying sediment thickness gradually increases eastward over the IFB. The inferred subsurface structures and tectonic fabric in this region mainly trend N–S, NNE–SSW, NE–SW, NW–SE, NWW–SEE and E–W. The selected gravity profiles and inversion‐modelling results provide insights into the concealed complex thrust geometry and basement configuration. We construct a conceptual model based on gravity modelling results, which bring out half‐graben structures and fault‐block features. These inferred structures are attributed to basement faults, steep anticlinal structures and synclinal basins that act as migration paths and oil traps and are potentially favourable zones for hydrocarbon resources.