Petrography and geochemistry of the Neoproterozoic sedimentary rocks from the Batal Formation of Spiti Basin: implication on provenance

The petrography and geochemistry of the siliciclastic rocks of Batal Formation, Spiti Basin were studied to define the provenance, tectonic setting, and depositional environment. Petrographical studies show that the percentage of quartz in sandstone varies from 70 to 80%, whereas in siltstone and shale, it varies from 50 to 60%. Similar pattern of chondrite-normalized REE, with enriched LREE, depleted HREE, and a negative Eu anomaly, suggests that the source rock is of felsic type. Significant correlation between Zr versus Yb and ΣHREE indicates that these sediments are influenced by sediment recycling. The Ni/Co and Cu/Zn ratios suggest that sediments were deposited under low to moderate oxygenated conditions, while the CIA values and A-CN-K plot reflect moderate to intense weathered source area with the presence of clay minerals derived during the cold period. The major element–based multidimensional tectonic discrimination diagrams suggest an active marginal setting for the sediments of Batal Formation. Further, the discrimination diagrams equally suggest that these sediments were derived from sedimentary provenance and to some extent from the felsic igneous provenance.