Characteristics of the paleosol at the Archean - Proterozoic contact in the Aravalli Craton, NW India and paleoclimatic implications

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The Archean – Proterozoic contact (APC) in the NW Indian craton is punctuated by several occurrences of white mica-rich lithologies, which are locally quarried in small pits. These Al-rich lithologies (subsequently metamorphosed), described as ‘paleosols’ developed over an Archean granitic basement, offer an ideal setting to deduce ambient atmospheric conditions as they are formed at the atmosphere-lithosphere interface. Previous studies have proposed formation of APC paleosols under oxygen-deficient conditions on the basis of geological and geochemical criteria. Such an interpretation needs to be reassessed in the light of our discovery of an iron-rich horizon from upper part of the Tulsi-Namla section. These paleosols were formed between 2.5 and 2.1 Ga, the interesting time interval of changing atmospheric conditions and our study would provide information not attempted so far from Archean cratons in India. In this proposal we apply for funding for a field study and for high precision geochemical and mineral-chemical data to deduce the paleoweathering conditions. The findings will be compared with similar settings from well-studied Archean terranes in South Africa, Canada and Australia.