Abstract
Abstract A number of crustal-scale shear zones have developed along the southern margin of the Singhbhum Craton, in the boundary with the Neoarchean Rengali Province and the Meso-Neoproterozoic Eastern Ghats Belt. The cratonic part, evolved in a suprasubduction zone setting, bears imprints of late Mesoarchean orogenic episode (D1C) at ca. 3.1 Ga with folding and thrust imbrication of the cratonic rocks. The succeeding orogenic imprint is etched in the Neoarchean (~2.8 Ga) with development of the Sukinda thrust along the craton margin and thrust-related deformation of the rocks of the Rengali Province (D2C-D1R). The latter event remobilized cratonic fringe with development of a spectacular E-W trending transpressional belt in the Southern Iron Ore Group rocks cored by the Sukinda ultramafics. In the Eastern Ghats Belt, the major ultrahigh-temperature orogeny took place during the Grenvillian-age (~1.0-0.9 Ga) assembly of the supercontinent Rodinia. This belt eventually got juxtaposed against the expanded Singhbhum Craton in the end-Neoproterozoic time (~0.5 Ga) along the Kerajang Fault Zone. This latter event remobilized a large part of the Rengali Province (D2R) with development of an intraterrane transpressional belt bounded by the Barkot Shear Zone in the north. The northern fringe of the intruding Eastern Ghats Belt developed a complex network of strike-slip fault system under this impact, probably an outcome of tectonic activity along the Kuunga suture, which signifies the joining of greater India with East Antarctica. The present synthesis visualizes early development in the craton through formation of a typical orogenic sequence, imbricated in thrust piles, resulting from a ca. 3.1 Ga orogeny. Further cratonic expansion was achieved via repetitive accretion and remobilization, development of crustal-scale faults and transpressional belts at ca. 2.8 Ga and ca. 0.5 Ga, much in a similar fashion as documented along oblique convergent margins of all ages.
Highlights
Geological record of cratons propounds that its cores, formed mostly in the Paleo-Mesoarchean time [1,2,3] and eventually swelled through some semblance of tectonic processes, succor as archives to realize the early Earth tectonic processes and their periodicity [4,5,6]
We focus on the archival rock record of one of the Earth’s oldest preserved cratons, the Singhbhum Craton (SC) in India, its southern margin with the Meso-Neoproterozoic Eastern Ghats Belt (EGB), which is the locale of fault-induced juxtaposition of disparate crustal blocks having diverse ancestry and geological records
(2) A second phase of orogenesis (~2.8 Ga) occurred along the craton margin after a tectonic quiescence of ~0.3-0.2 Ga that accreted the Rengali Province (RP) against the SC along the Sukinda thrust-Barkot Shear Zone (BSZ) fault system
Summary
Geological record of cratons propounds that its cores, formed mostly in the Paleo-Mesoarchean time [1,2,3] and eventually swelled through some semblance of tectonic processes, succor as archives to realize the early Earth tectonic processes and their periodicity [4,5,6]. Identification and characterization of such craton margin crustal-scale shear zones are challenging tasks which eventually could lead to better understanding of the tectonic styles and processes, operative way back in geological time scale In this contribution, we focus on the archival rock record of one of the Earth’s oldest preserved cratons, the Singhbhum Craton (SC) in India, its southern margin with the Meso-Neoproterozoic Eastern Ghats Belt (EGB), which is the locale of fault-induced juxtaposition of disparate crustal blocks having diverse ancestry and geological records. The other key aspect that remains to be tackled is how the cratonic rocks and adjunct mobile belts responded to disparate orogenic cycle right from the Mesoarchean till Neoproterozoic and whether these responses can be correlated with perceived supercontinent cycles To address these issues, we focus on a structural transect covering this boundary region to disentangle the nature of deformation and tectonothermal saga of the terrane. Assimilation of deformational and metamorphic inputs in the contexts of geochronology is anticipated to furnish crucial hints to the accentuated growth of the Singhbhum southern cratonic margin and to raise pertinent issues related to the generation of the crustal-scale fault structures in this region and their role in the global supercontinent cycle
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