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SUMMARY The Saurashtra Peninsula in northwest India, lying at the northern boundary of the Deccan Volcanic Province, is almost entirely covered by these volcanics. Analogue seismic refraction/wide‐angle reflection data along a 160 km long profile, from Navibandar to Amreli, were collected during 1977 to determine the crustal configuration. Reprocessing of these data, after digitization, has yielded a crustal model that is significantly different from the earlier model of Kaila et al. The model shows the upper crust down to a depth of 16 km in the west and 13 km in the east and underplating (velocity of 7.20 km s−1) of the lower crust. The Moho is at a depth of ∼36 km in the western part and at 32–33 km in the eastern part; the change of depth is quite sharp almost in the middle of the profile. Similar depth changes are seen in other crustal horizons indicating a deep fault that is in line with the extension of the Proterozoic Aravalli trend in to the Saurashtra Peninsula. The crustal structure in the eastern part is similar to that in the Cambay Basin and indicates that the crust to the east of the proposed fault is uplifted. The uplifted region extends as far as another arm of the Aravalli trend that turns eastwards. Crustal underplating in large parts of western India is confined to the corridors affected by the passage of India over the Réunion Plume in the Late Cretaceous. The shallower Moho appears to be confined to the areas close to the axis (trace of the plume) on Earth's surface of the plume.

During northward movement of the Indian sub-continent, after its breakup from the Gondwanaland in the Late Cretaceous, the western part of India traversed over the Reunion plume. The Saurashtra peninsula and the Cambay Basin are two important geological regions in this part. Two and half dimensional density models, based on the crustal seismic structure, were generated to establish a relationship between these two regions. These models indicate that the crust is 32-33 km thick in the eastern Saurashtra and the northern part of the Cambay Basin. The shallower crust is in a triangular region formed by the extension of the western limb of the Proterozoic Aravalli trend in Saurashtra, its eastern limb and the Narmada fault in the south. Compared to 36-37 km thick crust to the west and 38-40 km to the east of this region the crust in the above triangular region is uplifted by 4 to 6 km. This uplift took place either after the deposition of Mesozoic sediments or was concomitant with the rise of Reunion plume prior to the extrusion of the Deccan volcanics as the region was close to the axis of the plume.

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