Abstract In this paper the authors review various applications of analysing fabric in granites from Indian cratons using anisotropy of magnetic susceptibility (AMS). First the general importance of AMS in identifying the internal fabric in massive granitoids devoid of visible foliations/lineations is highlighted. Subsequently, three important applications of AMS in granitoids are discussed. (a) The case of Godhra Granite (southern parts of the Aravalli Mountain Belt) is presented as an example of the robustness of AMS in working out the time relationship between emplacement/fabric development and regional deformation by integrating field, microstructural and magnetic data. (b) AMS orientation data from Chakradharpur Granitoid (eastern India) are compared with field-based information from the vicinity of the Singhbhum Shear Zone to highlight the use of AMS in kinematic analysis and vorticity quantification of syntectonic granitoids. (c) Magnetic fabric orientations from the Mulgund Granite (Dharwar Craton) are presented to document the application of AMS in recognizing superposed deformation in granitoids. Moreover, AMS data from Mulgund Granite are also compared with data from another pluton of similar age ( c. 2.5 Ga) from the Dharwar Craton (Koppal Granitoid; syenitic composition). This highlights the use of AMS from granitoids of similar absolute ages in constraining the age of regional superposed deformation.

Abstract Reconstructing the stratigraphic architecture of deposits prior to Cenozoic Himalayan uplift is critical for unravelling the structural, metamorphic, depositional and erosional history of the orogen. The nature and distribution of Proterozoic and lower Paleozoic strata have helped elucidate the relationship between lithotectonic zones, as well as the geometries of major bounding faults. Stratigraphic and geochronological work has revealed a uniform and widespread pattern of Paleoproterozoic strata >1.6 Ga that are unconformably overlain by <1.1 Ga rocks. The overlying Neoproterozoic strata record marine sedimentation, including a Cryogenian diamictite, a well-developed carbonate platform succession and condensed fossiliferous Precambrian–Cambrian boundary strata. Palaeontological study of Cambrian units permits correlation from the Indian craton through three Himalayan lithotectonic zones to a precision of within a few million years. Detailed sedimentological and stratigraphic analysis shows the differentiation of a proximal realm of relatively condensed, nearshore, evaporite-rich units to the south and a distal realm of thick, deltaic deposits to the north. Thus, Neoproterozoic and Cambrian strata blanketed the northern Indian craton with an extensive, northward-deepening, succession. Today, these rocks are absent from parts of the inner Lesser Himalaya, and the uplift and erosion of these proximal facies explains a marked change in global seawater isotopic chemistry at 16 Ma.

Abstract The Aravalli Mountains and neighbouring areas have well-preserved records of a protracted history of development of Precambrian basins, which spans about 2500 myr of the Earth’s history. The oldest depositional basins are the greenstone belts that occur within the Archaean gneiss–granite terrain. Geochronological data indicate evolution of one such greenstone belt from 3300 to 2850 Ma. The younger Proterozoic cover successions include the Aravalli Supergroup, Delhi Supergroup and Sirohi Group, which evolved during three successive orogenic cycles spanning between c. 2200 and c. 1850 Ma, c. 1700 and c. 1450 Ma, and c. 1000 and c. 850 Ma, respectively. Each of these lithostratigraphic units evolved in separate basins having distinctive tectonic, metallogenic and evolutionary histories. The inversion of the youngest ‘orogenic’ basin marks the final cratonization of the Precambrian Aravalli crust at around 850 Ma. The succeeding depositional episodes include formation of ephemeral basins during the early phase of the plume-related Malani Group from 780 to 730 Ma, and the formation of the Marwar Supergroup deposited in stable platformal basins marks the terminal phase of the Precambrian crust-building history in the region.