The Rengali Province, east India: a result of the Singhbhum Craton’s southward accretion or a ~1000-km dragging of the East Indian Shield?

Major geodynamic processes driving Archean cratonic growth remain enigmatic, but rocks formed during Earth’s early evolution provide critical constraints on Archean geodynamics. The Rengali Province (RP) of eastern India is an Archean terrane situated between low-grade Archean rocks of the Singhbhum Craton (SC) to the north, the Neoproterozoic granulites of the Eastern Ghats Mobile Belt (EGMB) to the south, and the Archean high-grade rocks of the Bastar Craton (BC) to the west. The RP is bounded by the Barakot–Akul Shear Zone (BSZ) along its northern margin and the Kerajang Shear Zone (KSZ) to the south. As the RP provides a window into the cratonic growth processes, tectonic characterization of this province is essential. Previous studies have variably interpreted the RP as either an exhumed lower-crustal root of the SC, with the BSZ representing a thrust boundary or as a rotated fragment of the BC juxtaposed against the SC along a strike-slip contact. To resolve these contrasting models, we integrate field observations with petrology, microstructural analyses by electron backscatter diffraction, thermobarometry and geochronological investigations. The province comprises two contrasting metamorphic lithounits: (1) a southern high-grade unit composed of migmatites, augen-gneiss, charnockite, and metabasics; and (2) a northern low-grade unit consisting of actinolite schists and quartzites. Integrated field observations, petrography, and microstructural analyses indicate that high-grade and low-grade units followed distinct tectonometamorphic histories prior to their juxtaposition. Following gneissosity development, the high-grade unit records two generations of folding, followed by N–S-trending sinistral shearing event that overprinted the earlier foliation forming dome-and-basin structure. However, the low-grade unit preserves a single folding episode. Both units subsequently experienced an ESE–WNW-trending dextral shearing event at ~490–470 Ma under greenschist-facies conditions activating prism <a> slip-system of quartz, suggesting their juxtaposition during Gondwana assembly. Field-based kinematic indicators and vorticity analyses further demonstrate that the BSZ and KSZ represent dextral strike-slip shear zones. Thermobarometric calculation on the charnokcite suggests an average P-T conditions of ~750°C and ~5 kbar, while the low-grade records greenschist-facies condition evident from stabilization of actinolite+chlorite+albite+epitode+quartz±sphene in actinolite schist. Metabasics from the high-grade unit records ferropargasite+anorthite+quartz composition, indicative of upper amphibolite facies conditions. Published P–T estimates from the BC closely resemble those of charnockitic units of the RP and the metabasic rocks of high-grade unit exhibit geochemical affinities with BC metabasics. These correlations suggest that the high-grade unit of the RP is Bastar-affiliated, while the low-grade unit represents a fragment of the SC. The kinematics and P–T conditions of shear zones within and surrounding the RP closely resemble the Mahanadi and Cauvery Shear Zone. These similarities imply that, prior to Gondwana assembly, high-grade and low-grade lithounits of the RP evolved independently and were subsequently translated by ~1000 km into their present juxtaposition. This large-scale displacement was partitioned across multiple dextral shear zones farther south, accommodating small-circle motions. These shear zones can be correlated with the dextral strike-slip shear zones in East Antarctica, suggesting that this crustal-scale shear system extends beyond the Indian Shield and likely continues into the Antarctic interior.