Articles written in Journal of Earth System Science

    • Geochemistry of Barail sandstone in Champhai, Mizoram: Implications on provenance and weathering history


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      Mizoram is geologically young comprising entirely of sedimentary rocks. The Oligocene age of Barail group of sedimentary rocks, exposed near the Indo Myanmar mobile belt, i.e., Champhai area, Mizoram have been studied to infer the provenance and paleoweathering history. The significance of the work is that it will uncover and reconstruct origin of Barail sandstone and restore the tectonic and paleoclimatic conditions based on petrography and geochemistry of the sandstone. The geochemical classification based on diagrams of log(SiO$_{2}$/Al$_{2}$O$_{3}$) vs . log(Na$_{2}$O/K$_{2}$O) and log(SiO$_{2}$/Al$_{2}$O$_{3}$) vs . log(Fe$_{2}$O$_{3}$/K$_{2}$O) of the Barail sandstones indicated that the sandstones belong to litharenite and wacke. The geochemical characteristics of the rock are plotted in various binary and ternary diagrams and selected ratios of elements are interpreted in the light of source rock characteristics. The Chondrite normalised REE pattern show similar pattern to UCC (Taylor and McLennan 1985) with an enrichment of LREE and depletion of HREE. The ratio of Al$_{2}$O$_{3}$/TiO$_{2}$ and the ternary diagram of La–Th–Sc indicate felsic to intermediate source. Similarly, the high LREE/HREE ratios and negative Eu anomaly (La/Lu)$_{cn}$, ratios of Eu/Eu*, La/Sc, La/Co, Cr/Th, Th/Sc, Th/Co and Cr/V ratio indicate felsic source. The binary diagram between ratios of Zr/Sc vs. Th/Sc inferred volcanic source. The sediments are also found to be derived from recycled sedimentary rock which is proved by ratios of Zr/Sc and Th/U. The A–CN–K diagram and weathering indices such as CIA, PIA shows moderate to intense weathering in the source area. The investigated Barail sandstones are chemically mature as indicated by the ICV while the ratio of SiO$_{2}$/Al$_{2}$O$_{3}$ indicated moderate sediment maturity.


      $\bullet$ The present work focused on provenance and paleao-weathering history of the sedimentary rocks exposed in Champhai District of Mizoram, located in the eastern region of Indo-Myanmar border.

      $\bullet$ The research is mainly based on petrological and geochemical approaches. The work revealed the systematic nomenclature of the sandstone to sublitharenite and wacke.

      $\bullet$ The research found out that the detrital grains of the investigated sandstones are derived from active continental areas and the provenances which are cosmopolitan in nature varying from igneous and metamorphic to recycled sedimentary terrains.

      $\bullet$ The work also inferred intermediate to intense weathering phenomena in the provenance.

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