Basalt–sediment configuration in the Tapti rift of central Indian region as derived from magnetotelluric (MT) studies and hydrocarbon prospects

Geochemical studies in Deccan syneclise have identified anomalous concentration of light hydrocarbon gases in the surface soil from the Tapti rift region in Narmada–Son Lineament, India. We have reanalysed and modelled broadband MT data from this region to delineate basalts and underlying sediment configuration, which is favourable for hydrocarbon accumulation. We carried out 1D and 3D modelling of the MT data for this purpose. Modelling studies brought regions of thick sub-basaltic sediments towards NW and SW of Nepanagar. But very less anomalous light hydrocarbon gas concentration is observed along NW of Nepanagar. This may be due to the presence of thick basalt cover in that area, which prevents the leakage of gaseous hydrocarbons on to the surface soil. We observed a comparatively thin basalt layer and high sediment thickness with a high concentration of light hydrocarbon gases near to Burhanpur area, which strongly suggests better hydrocarbon prospects in the area. It is inferred that the relatively thin and fractured/vesicular nature of basalt in this region facilitates the upward migration of light hydrocarbon components to the surface soil.