PALEOPROTEROZOIC MAGMATISM AND ITS ROLE IN THE DEVELOPMENT OF DUDHI GRANITIC GNEISSES, CENTRAL INDIAN TECTONIC ZONE (CITZ), INDIA: EVIDENCE FROM GEOCHEMISTRY AND GEOCHRONOLOGY OF GRANITIC GNEISSES
The Dudhi Granitic Gneisses (part of Dudhi Gneisses Complex) of the Mahakoshal Belt (MB) is located in the northern part of the Central Indian Tectonic Zone (CITZ), India. The present study reports on the whole rock geochemistry, U-Pb geochronology combined with Sm-Nd isotope data from the Dudhi Granitic Gneisses (DGGs) to understand their crustal-mantle evolution that plays a crucial role in the early Earth´s history. This study reports distinct episodes of granitic Paleoproterozoic magmatism at ~1.71-1.75 Ga. The DGGs are strongly metaluminous, display A2-type affinity, and have high Ga/Al ratio and K2O content, and low Rb content. The DGGs also exhibit enrichment in high field strength elements (HFSE) (such as Zr, Hf, Th, and U) and rare earth elements (REE) (excluding Eu) whereas depletion in large ion lithophile elements (LILE) (Sr, Ba). Similarly, the negative anomalies obtained for elements such as Nb, Sr, Eu, P, Ti, and elemental ratios like Y/Nb, Th/Nb, La/Nb, and Ce/Pb reveal originated from crustal sources. The negative values of ɛNd(t) (‒5.7 to ‒0.4) and Nd-model ages (TDM: 2068‒2420 Ma) also support the claim of their crustal origin. All these geochemical signatures suggest strong evidence of partial melting of the Archean Bundelkhand crust and are formed within plate tectonics. In addition, the Paleoproterozoic granitic magmatism of MB in the CITZ is linked to the breakup of the Columbia supercontinent, which comprised the lithosphere of the CITZ.
Keywords: Dudhi granitic gneisses (DGGs), Central Indian Tectonic Zone (CITZ), Mahakoshal Belt (MB), Sm-Nd isotope, zircon U-Pb ages, A-type granite, Columbia supercontinent.