A review on deformation structures of different terranes in the Precambrian Aravalli-Delhi Mobile Belt (ADMB), NW India: Tectonic implications and global correlation

The Aravalli-Delhi Mobile Belt (ADMB) in the northwestern part of the Indian Shield represents the final stage of a complex tectonic evolution witnessed by the recognition of three distinct orogenies that have resulted in northwestward accretion of the terranes belonging to Archaean to Neoproterozoic ages. In this contribution, a review of the deformation structures of different terranes is discussed with their tectonic implications and global correlation with other supercontinent assemblies. In the west, the NE-SW trending Neoproterozoic South Delhi terrane is marked by coaxial folding between DF1 and DF2 along the NE-SW axis and cross folded by DF3 folds in the NW-SE axis. Several meso- to large-scale DF2 thrusts and DF4 fractures occur in the belt, that acted as channels for the exhumation of granulite and basement gneisses. Excess shortening led to orogen parallel extension and lateral escape of the material that reactivated the DF2 thrusts as strike-slip faults. Based on the ages of syn-DF1 granite gneisses, DF4 fractures, the South Delhi orogeny has been constrained between 0.87 and 0.6 Ga. The Paleoproterozoic North Delhi Terrane is marked by a coaxial folding between NF1 and NF2 folds and later cross-folded by NW-SE trending NF3 folds, producing dome- and basin-structures. Age of syntectonic granite and late-stage metamorphism constrain the north Delhi orogeny between 1.8 and 0.96 Ga. The Paleoproterozoic Aravalli Terrane is divided into a shallow-marine eastern and deeper marine western part by the Rakhabdev suture zone. The entire assemblage of terranes was folded by NE-SW isoclinal and recumbent AF1 folds which, with progressive deformation, were reoriented with a E-W axial trend. The AF2 is upright and NE-SW trending. The AF3 folds are E-W to NW-SE trending and have produced type 1 and type 2 interference patterns, with AF2 and AF1 respectively. Age of syn-AF1 migmatisation in the northern part and syn-AF3 granites in the south constrain the Aravalli orogeny between 1.7 and 0.96 Ga, coeval with the North Delhi orogeny. The granulite and charnockite were tectonically emplaced within the Sandmata Complex during the Aravalli orogeny. The Archean Bhilwara terrane, produced from the Bhilwara orogeny, marks the stabilisation of the crust in NW India by the intrusion of Berach and equivalent granites at 2.6 Ga. The terrane is divided into the Sandmata and Mangalwar complexes that consist of migmatite gneisses with slivers of greenstone. Several Neoarchean to Paleoproterozoic volcano-sedimentary schist belts were tectonically interlaced within the Mangalwar Complex. The migmatitic rocks of the terrane show flow folding in various directions while the schist belts are characterized by extremely appressed NE-SW trending reclined folds (BF1 and BF2), inverted BF2 folds, E-W open BF3 folds, and multiple strike-slip shear zones and thrusts. The ADMB exhibits a syntaxial bend in the eastern part attributed to indentation tectonics by Berach granite during syn-South Delhi orogeny. The Aravalli orogeny can be correlatable with Nuna orogeny, whereas the South Delhi orogeny can be correlated with the Pan-African orogeny that gave rise to Columbia and Gondwanaland Supercontinent assembly. The Grenville orogeny has experienced thermal rejuvenation in the Aravalli and Bhilwara terranes.