• Provenance, tectonic setting and source-area weathering of the lower Cambrian sediments of the Parahio valley in the Spiti basin, India

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      Lower Cambrian; provenance; tectonic setting; chemical weathering.

    • Abstract


      The geochemical study of siliciclastic rocks from the Lower Cambrian of Parahio Valley has been studied to describe the provenance, chemical weathering and tectonic setting. The K ₂O/Al ₂O₃ ratio and positivecorrelation of Co (r = 0.85), Ni (r = 0.86), Zn (r = 0.82), Rb (r = 0.98) with K₂O reflects that the presence of clay minerals control the abundances of these elements and suggests a warm and humid climate for this region. The chondrite normalized REE pattern of the samples is equivalent to uppercontinental crust, which reflects enriched LREE and flat HREE with negative Eu anomaly. The tectonic setting discriminant diagram log[K ₂O/Na ₂O] vs. SiO ₂; [SiO ₂ /Al ₂O ₃] vs. log[K ₂O/Na ₂O]; [SiO ₂/20] – [K ₂O+Na ₂O] – [TiO ₂+Fe ₂O ₃+MgO] indicates transitional tectonic setting from an active continental margin to a passive margin. The discriminant function plot indicates quartzose sedimentary provenance, and to some extent, the felsic igneous provenance, derived from weathered granite, gneissic terrain and/orfrom pre-existing sedimentary terrain. The CIA value indicates low to moderate degree of chemical weathering and the average ICV values suggests immature sediments deposited in tectonically active settings. The A–CN–K diagram indicates that these sediments were generated from source rocks of theupper continental crust.

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  • Journal of Earth System Science | News

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