Evidence for Mesoarchean subduction in Southern Bundelkhand Craton, India: Geochemical fingerprints from metavolcanics of Kurrat - Girar - Badwar Greenstone Belt

Abstract

The metavolcanic suites from southern Bundelkhand Craton, India provides a comprehensive record of the little-explored evolutionary history of Southern Bundelkhand Craton. The present work is a detailed petrological and geochemical account of the metavolcanics to (i) constrain the mantle processes and tectonic realm involved in its genesis and (ii) evaluate the Archean geodynamics of Bundelkhand Craton. The metavolcanics of Kurrat, Badwar and Girar are compositionally slightly evolved tholeiitic basalts. Chondrite normalized REE distribution pattern reflects a slightly super-chondritic LREE distribution pattern (Kurrat metavolcanics, KMV: (La/Yb)N = 1.9–2.9, Badwar-Girar metavolcanics, BGMV: (La/Yb)N = 0.89–2.86) and negative Nb and Ti anomaly on a primitive mantle normalized trace element variation diagram. ƐNd(t) of the samples vary from −1.0 to 6.3 and ƐNd(t) versus 87Sr/86Sr diagram imply the absence of crustal contamination. These attributes are consistent with the formation of the metavolcanics from a slightly enriched heterogeneous mantle source at shallower depths where the original depleted MORB underwent later episode(s) of enrichment via fluid addition. The metavolcanics originated in an intra-oceanic subduction setting, essentially exhibiting back-arc basin basalts (BABB) characteristics. TDM age (3.07 Ga) calculated for the KMV is coherent with the 2.98 Ga age of the BGMV from the adjacent Badwar-Girar volcano-sedimentary sequence. Collectively, all the features implicate the formation of metavolcanics in a modern style Mesoarchean extension-subduction geodynamic regime.