Chemical diagenesis of Siwalik sandstone: Isotopic and mineralogical proxies from Surai Khola section, Nepal

Mineralogical composition also shows that diagenesis increases with depth. Clay minerals (< 2μ) separated from sandstone include smectite, illite, chlorite and kaolinite. Relative increase in the abundance of illite and decrease in the abundance of smectite indicate illitization of smectite with increase in burial depth. Presence of corroded features in K-feldspar suggests that dissolution of this mineral supplied potassium for illite formation.