---

Aravalli-Delhi Fold Belt

Schematic diagrams showing
(a) Modification of the mantle lithosphere underneath the ADFB orogen due to the delamination and/or mechanical slab breakoff of the subducting Bundelkhand craton along the Great Boundry Fault.
(b) A sequence of mantle thermal anomalies invading the lithospheric base during the Neoproterozoic MIS and mafic alkaline complexes of the K/T boundary must have gradually modified the lithosphere of the Marwar Block.

The fold belts, which border the cratons, are the building blocks for understanding the origin and modification of older continents. The Aravalli-Delhi Fold Belt (ADFB) in northwestern India provides evidence of crustal block accretion due to continental collision, whereas the Malani Igneous Suite (MIS) modified with widespread magmatism. We applied a 2D integrated modelling approach which combines terrestrial gravity anomaly, heat flow data, satellite-based geoid, and topographic datasets to model the lithospheric architecture along a 1000-km long WNW-SSE geo-transect across northwestern India, which has been deformed in the past. Schematic illustrations depict various stages of crustal and lithospheric structures developed during the evolution of the Marwar-ADFB-Bundelkhand protocontinent of NW India. Figure (a) illustrates the alteration of the mantle lithosphere underneath the ADFB orogen caused by the delamination and/or mechanical slab breakoff of the subducting Bundelkhand craton along the Great Boundary Fault. Sub-vertical Phulad/ Erinpura granite is the product of andesite-decide-granite magma that ascended to upper crustal levels along the Phulad shear zone, leaving mafic magma at the base of the crust as an underplate. Figure (b) demonstrates a sequence of mantle thermal anomalies invading the lithospheric base during the Neoproterozoic MIS, and the mafic alkaline complexes of the K/T boundary must have gradually modified the Marwar Block's lithosphere.

---