Research Projects

Earth's crust, serves as an interface with the hydrosphere and atmosphere playing, a crucial role in Earth evolution. Currently, subduction zones and mid-oceanic ridges are the major crust building centers. In contrast, the nature of the crust and its tectonic setting in the Archean is enigmatic. The Archean cratons host rock records that can be studied to understand the origin and evolution of early continental crust. The timing of large-scale early mantle differentiation and generation of complementary continental reservoir is highly debated because, the large fraction of the crust formed during the Eoa-Mesoarchean either eroded away or recycled back into the mantle. The small fraction of this primitive crust, or remnant/fragments of which are fortuitously preserved in the cores of cratons as a TTGs crust or as detrital mineral grains can be used to comments on the geodynamic regime of continental crust formation and when did the modern-day subduction commenced. The proposed tectonic model for crust formation during Archean can be classified into two groups; stagnant lid vs. mobile lid models. The stagnant lid scenario advocates for a stagnant tectonic model, involving an upwelling mantle plume where the continental crusts were formed by episodic melting and delamination at the base of the thickened lithosphere. However, the mobile lid tectonic model supports the horizontal plate motion very similar to the modern-day Arc-like environment. The debate around when did in the Earth's past modern-day like plate tectonics become fully operational remains one of the key areas of contemporary crustal evolution research. It has been proposed that the compositional change of the Earth's crust from mafic to felsic had significant effect on the oxidative efficiency of the Earth's outer surface. Therefore, characterizing the nature, quantity, and age of the early crust is crucial. However, the major hindrance to this is the large portion of the primary rock records are lost and are presently accessible only as detrital grains in sedimentary packages. This work aims to understand the Eoarchean to Mesoarchean continental crust growth and evolution in Dharwar, Singhbhum, and Bastar Cratons of India. These cratons host some of the oldest granite-greenstone associations of age c. 3.45 Ga within Indian Shield. However, the metasedimentary successions preserve some of the oldest detrital zircon grains c. 3.95–3.65 Ga. The detailed characterization of mineral inclusions hosted in detrital zircon, and trace elements composition can be coupled with U-Pb geochronology, and in-situ Si-Sr-Hf isotopes in zircon to constrain age, provenance, and related igneous processes. These elemental and isotopic proxies can be efficiently used to unravel the volume of mafic vs. felsic crust and relative contributions of juvenile vs. recycled crust during Eoarchean to Mesoarchean continental crust formation, as well as timing of geodynamic regime transitions of crust formation.