Geological evolution of the Proterozoic Betul belt (∼2.16–0.95 Ga) of the Central Indian tectonic Zone: Its linkage to the assembly and dispersal of Columbia and Rodinia supercontinents

Abstract

The Proterozoic Betul Belt is an important supracrustal unit that records the protracted history of crustal accretion and growth in the Central Indian Tectonic Zone (CITZ). Here, we present results from systematic geological mapping, petrological, geochemical (including Sm-Nd isotope) studies, and U-Th-Pb geochronology on rocks from the Betul belt, with the objective of reconstructing its Proterozoic evolution and its link with past supercontinents. The Betul belt comprises ca. 2167 ± 11 Ma granite gneisses, ca. 2051 ± 80 Ma mafic volcanics (pillowed lava), 1715 ± 10 Ma rhyolite, and older granitoids (1671 ± 29 Ma) that have undergone multi-stage deformation and amphibolite-facies regional metamorphism. The bulk rock geochemistry of gneisses, pillow lava, and mafic intrusions are characterized by arc-like signatures, whereas the rhyolite and granites are anorogenic and back-arc related. The whole-rock geochemical and Sr-Nd isotopic compositions of pillow lavas and mafic intrusions suggest the involvement of recycled crustal material in their source, possibly in the form of associated sediments. The Betul granite gneisses were emplaced at 2167 Ma in a collisional setting by melting crustal protoliths having an affinity with the Bundelkhand craton and may constitute the basement for the supracrustal sequence. The supracrustal units, i.e., mafic volcanics and rhyolites, occur as a bimodal suite formed in the arc and back-arc environment with penecontemporaneous sedimentation. Bulk rock geochemistry and age data indicate two phases of A-type granite magmatism at 1674 Ma and 1079 Ma, with post-collisional geochemical traits forming within an anorogenic and back-arc setting, respectively. Younger post-orogenic granites (Navegaon) were emplaced in a back-arc setting at ca 1079–954 Ma, synchronous with a collisional event in the Sausar belt. Spot ages from monazite in Hbl gabbro yield a weighted mean of 1026 ± 97 Ma (MSWD = 0.15), reflecting Grenville-age regional metamorphism in the CITZ. The geological events recorded in the rocks of the Betul belt between ca 2167 Ga and 954 Ma correlate well with events that affected Laurentia, Baltica, Australia, and East Antarctica within the frameworks of the Columbia (ca. 2.1–1.7 Ga) and Rodinia (ca.1.2–0.9 Ga) supercontinents.