Betul-Chhindwara belt is part of Central Indian Tectonic Zone (CITZ) that includes Proterozoic basalt, rhyolite, quartzite, mafic-ultramafic rocks, volcano sediments and banded iron formation (BIF). Studied rhyolites and leuco-micro granites are deformed due to shearing and includes quartz, K-feldspar (microcline), muscovite, biotite and epidote. In some samples, feldspar has been sericitized due to interaction with hydrothermal fluids. The major element geochemistry of volcanic rocks clearly indicates acidic nature and falls in the rhyolite field. Rhyolites show difference in the enrichment of REEs and major element composition which help us divide them into two groups and also indicate heterogenous source. The rhyolites show very strong negative Eu anomaly, which indicates fractionation of feldspar. Positive anomalies of U-Th-Zr for the rhyolites indicate crustal involvement. The eNdt (t=1500) for the Group I rhyolites vary from-1.42 to-0.19 and for the Group II rhyolites vary from-5.81 to +0.14 and DM model ages for Group I rhyolites vary from 2284 to 2464 Ma and for Group II vary from 2174 to 2863 Ma. It is suggested that contemporary mafic magma of the Betul-Chhindwara belt while ascending from mantle sources interacted with the continental crust at different levels, supplying heat and fluids which reduced the melting points of the crustal source rocks, producing felsic melt of varying compositions. Tectonic discriminant diagrams and geochemical data indicate subduction zone tectonic environment for the genesis of the Betul-Chhindwara acidic volcanism. The acidic volcanics of Betul-Chindwara, Sakoli and the Bijli rhyolites from the adjoining areas display similarity in terms of the total alkali vs. silica diagram and many of the major and trace elements, including rare earth element characteristics. Compared to Betul Rhyolite, Sakoli Rhyolites are derived from less enriched source with less involvement of crust and/or the latter represents high degree of partial melting of similar source. They are considered contemporaneous to Betul Rhyolite based on geochronological data. Contrastingly, Bijli Rhyolite show highly fractionated patterns with high LREE enrichment indicating considerable crustal involvement which is very obvious for within plate magmatism, assigned for the Bijli rhyolites.

Northern Indian shield and the western Himalaya have an impressive record of mafic magmatism. The Aravalli Craton preserved 2.3 Ga komatiitic (picritic) and 2.1 Ga to 1.8 Ga tholeiities. Gwalior and Betul belts preserved 2.1 Ga and 1.5 Ga to 1.2 Ga tholeiites, respectively. Western Himalaya has preserved 2.1 Ga to 1.8 Ga tholeiites in Garhwal and Himachal regions. Studied rocks depict enriched REE, LILE and depleted HFSE. Whereas, komatiites/picrites represent higher degrees of partial melting (∼35-40%) at higher temperatures (∼1500° C), tholeiites represent lower degrees of partial melting (∼10%) at lower temperatures (∼1200° C). Our results indicate interaction of mantle plume with variably enriched SCLM sources, causing generation of these varied magmatic suites of rocks. Whereas, the higher temperature komatiitic/picritic melts from the Aravalli region appear to have been generated closer to the plume head, the lower temperature tholeiitic melts from the shield region and western Himalaya were generated towards the plume margins. Different terrains of the study have undergone plume tectonics causing development of the rift valleys, majority of these developed into aulacogens, except for the Aravalli basin, which developed into deeper marine facies.

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