Geochemistry of Banded Iron Formations (BIFs) from the Central Bundelkhand Craton, India: Implication for depositional setting

Abstract

The depositional environment of the Banded Iron Formations (BIFs) is highly controversial. The BIFs are type of chemical precipitates characterized by presence of alternating layers of iron and silica-rich. Paleo-Mesoarchean BIFs of the Central Bundelkhand Greenstone Belt (Babina-Mauranipur-Mahoba) occur along with the E–W trending of the Bundelkhand Tectonic Zone (BTZ) gives us opportunity to study the depositional environment during Archean Eon. The lithological association of BIFs in the Babina and Mauranipur areas consists of pillowed basic–ultrabasic volcanics and metasediments whereas the Mahoba´s BIFs and quartzite occur within basic volcanics. The bulk geochemical composition of BIFs shows the high content of FeOt with an average of 51.57 wt. %. The Babina´s BIFs show relatively lower concentration of V, Cr and Co in comparison to the Mauranipur and Mahoba. The significant negative Ce anomaly implies the signature of a deep marine source of the Bundelkhand BIFs. The samples from Babina show less Y/Ho ratios, along with lack of relativelyhigh Zr, Th, and Hf suggest that terrestrial material input was insignificantor very less during BIFs precipitation. Most of the BIFs from the Mauranipur and Mahoba show intermediate Y/Ho ratio suggesting chemical precipitation of BIFs from a mixture of seawater and high-temperature hydrothermal fluids generated from a back-arc spreading centre. The geochemical characteristics indicate that these BIFs are formed by volcanogenic hydrothermal activity in aback-arc tectonic setting. The Rare Earth Elements (REE) patterns suggest the role of high-T hydrothermal fluid for the deposition of BIFs in the Babina and Mauranipur greenstone belts whereas low-T hydrothermal fluid is responsible for the Mahoba greenstone belt deposition. Their geochemical variation also suggests the shallowing of the proto-basin from the Babina (west) to Mahoba (east).