Geochemical study of upper Bhuban sandstone in Muthi, Mizoram, India


Sandstones from the Upper Bhuban formation were measured for major oxides by X- Ray Fluorescence Spectrometry (XRF) in order to investigate palaeo-weathering, geochemical classification, and tectonic setting of the basin. The Muthi sandstone was found to have moderate to high content of SiO2 ranging from 64.54 to 76.66 wt% with an average value of 71.73 wt%. The Al2O3% content was high ranging between 10.78 to 18.19 wt% and 14.93 wt% (average). The high value of Al2O3 could be due to alteration of K-feldspar. Geochemically, the sandstone could be classified as arkose, litharenite and wacke. The sandstones were depleted in CaO (0.57) and enriched in Al2O3, Fe2O3 and Na2O. The value of chemical index alteration (CIA) in the Muthi sandstone was high 72.25 to 85.46 an average value of 79.45 indicating high intensity of chemical weathering in the source areas. The average CIA value (79.45) was above than that (50) of the upper continental crust. The geochemical parameters suggest an active continental margin for the upper Bhuban sandstones.

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