Aravalli Supergroup

Aravalli Supergroup
Name	Aravalli Supergroup
Type	Supergroup
Period	Paleoproterozoic–Archean (complex)
Lithology	Metapelite, metapsammite, metavolcanic, BIF, marble, quartzite
Namedfor	Aravalli Range
Region	Rajasthan, Gujarat, Madhya Pradesh, Haryana
Country	India

Aravalli Supergroup The Aravalli Supergroup is a major Paleoproterozoic to Neoarchean stratigraphic succession exposed in the Aravalli Range of western India, representing one of the oldest cratonic successions on the Indian subcontinent and influencing regional mining in Rajasthan, Gujarat, and Madhya Pradesh. It comprises a thick assemblage of metasedimentary and metavolcanic units that record interactions among ancient crustal blocks such as the Bundelkhand Craton, the Marwar Craton, and the Bastar Craton during Proterozoic tectonism linked to broader events like the assembly of Columbia and the evolution of the Indian Shield. The succession has been a focal point for geological investigations by institutions including the Geological Survey of India, the Indian Institute of Technology Roorkee, and international collaborations with researchers from the United States Geological Survey and University of Cambridge.

Geology and Stratigraphy

The succession is classically subdivided into multiple stratigraphic groups and formations correlated with regional units such as the Delhi Supergroup and the Bhima Group, and has been mapped in detail by the Geological Survey of India, state geological departments of Rajasthan and Gujarat, and researchers from Banaras Hindu University and University of Delhi. Major stratigraphic divisions recognized in the field include lower turbiditic metasediments and upper volcaniclastic sequences that have been correlated with successions in the Vindhyan Basin and parts of the Bastar Craton, with lithostratigraphic names applied at localities near Udaipur, Alwar, and Mount Abu. Stratigraphic frameworks have been tested against regional structural maps produced by the Indian Space Research Organisation and geophysical surveys by the Council of Scientific and Industrial Research.

Lithology and Formation Processes

Lithologies include metapelite, metapsammite, banded iron formation (BIF), marble, quartzite, amphibolite, and felsic metavolcanics similar to sequences in the Labrador Trough and the Pilbara Craton, with depositional facies interpreted using comparisons to the Gondwana and Laurentia successions. Formation processes inferred from field relations, petrography at universities like IIT Bombay and IIT Kharagpur, and geochemical signatures from laboratories at Atomic Minerals Directorate indicate submarine volcanism, turbiditic sedimentation, chemical precipitation of BIF, and syn-depositional hydrothermal alteration analogous to processes documented in the Barberton Greenstone Belt and the Isua Greenstone Belt.

Tectonic Setting and Structural Evolution

The structural evolution records polyphase deformation, with thrusting, folding, and regional metamorphism tied to collisional events that juxtaposed cratonic blocks such as the Bundelkhand Craton and the Marwar Craton, similar to collisional histories reconstructed for Rodinia fragments and collisional belts like the Central Indian Tectonic Zone. Major tectonothermal episodes correspond to orogenic pulses interpreted in relation to events recorded in the Eastern Ghats Mobile Belt and the Sao Francisco Craton, with structural analyses undertaken by research groups at IISC Bangalore and the Wadia Institute of Himalayan Geology.

Age, Geochronology, and Correlation

Radiometric ages obtained from metamorphic and igneous units using methods developed at laboratories such as the Wadia Institute and international facilities (U–Pb zircon at GEOLAB-type centers) yield Paleoproterozoic to Neoarchean ages comparable to sequences in the Kaapvaal Craton, Yilgarn Craton, and Superior Province. Geochronological work by teams from the Geological Survey of India, Banaras Hindu University, and collaborators at the University of Oxford has produced U–Pb zircon, Sm–Nd, and Re–Os datasets that constrain deposition, magmatism, and metamorphism and support correlations with the Delhi Orogeny and cratonization events recognized in the Siberian Craton.

Mineralization and Economic Geology

The Supergroup hosts significant mineralization including base-metal sulfides, iron ore in banded iron formation comparable to deposits in the Pilbara, gold occurrences akin to those in the Witwatersrand Basin, and carbonate-hosted Pb–Zn mineralization analogous to deposits in the Mississippi Valley Type provinces, explored by companies and agencies such as the Mineral Exploration Corporation Limited, Hindustan Zinc, and multinational teams. Important mining districts include the Khetri Copper Belt, the Udaipur and Banswara iron-ore occurrences, and numerous gold and base-metal prospects evaluated by the Geological Survey of India and state mining directorates, with resource studies published by academic groups at IIT Delhi and JNU.

Paleoenvironments and Metamorphism

Depositional environments inferred from sedimentary structures, geochemistry, and facies analysis suggest submarine slope, shelf, and hydrothermal settings influenced by rift-related volcanism similar to environments in the Abitibi Greenstone Belt and the Tanzania Craton. Metamorphic grades range from greenschist to granulite facies in places exposed near Mount Abu and the Aravalli Hills, with metamorphic P–T paths documented by thermobarometric studies from laboratories at IIT Roorkee and IISc Bangalore that link heating events to regional orogenies such as the Delhi Orogeny and thermal episodes recorded in the Eastern Ghats.

Research History and Exploration

Investigation of the succession began with 19th and early 20th century surveys by the Geological Survey of India and colonial geologists who produced early maps later refined by post-independence workers at institutions including IIT Roorkee, Banaras Hindu University, and the Wadia Institute of Himalayan Geology, and through international collaborations with teams from the USGS, University of Cambridge, and Max Planck Institute. Modern research emphasizes integrated stratigraphy, U–Pb geochronology, isotope geochemistry, and geophysical imaging undertaken by consortia involving the Council of Scientific and Industrial Research, state agencies, and university departments that continue to revise stratigraphic nomenclature, tectonic models, and exploration strategies.

Category:Geologic formations of India Category:Paleoproterozoic geology Category:Aravalli Range