Abstract
Late Cretaceous sandstone succession of the Pab Formation in western Sulaiman Fold Thrust belt Pakistan was investigated for petrology and bulk rock chemistry to determine its source terrain, paleo-weathering and tectonic setting. The formation is mainly comprised of sandstone with reddish to maroon color shale and arenaceous limestone. Texturally, the sandstone is fine to coarse grained, sub-angular to well-rounded and moderately to well sorted. The sandstone is petrologically and geochemically classified as quartz arenite to sub lithic arenite. The detritus was mainly derived from plutonic acidic source. QtFL and QmFLt suggests that recycled orogeny and Craton Interior setting were major sources of sediments. Geochemical models support that the detritus was derived from quartzose sedimentary source terrain, suggest deposition in a passive continental margin setting. Average values of chemical indices are CIA 59% CIW 67% and CIV 12.70%, which suggest moderate to high degree of chemical weathering in source area, that may reflect humid climate condition in the source area. The petrographic study and geochemical models demonstrate that the Pab Formation is mostly composed of mature sandstone from acidic plutonic and low-grade metamorphic rocks terrain in recycled and Craton Interior setting deposited on western passive margin of Indian plate in Tethys Ocean.
Highlights
Provenance studies of siliciclastic sedimentary rocks often aim to determine the composition and geological evolution of the sediments' source region
The petrography reveals that low grade metamorphic and granitic rocks were the dominant source terrains
The geochemical ternary diagrams indicate the derivation of sandstone from quartzose recycled and lithic recycled orogeny
Summary
Provenance studies of siliciclastic sedimentary rocks often aim to determine the composition and geological evolution of the sediments' source region. The Pab Formation is the Late Cretaceous unit exposed in different parts of the Kirthar and Sulaiman Fold-Thrust Belts. Pab Formation has thoroughly been studied in Kirthar Fold-Thrust Belt for facies variation, provenance and reservoir potential for hydrocarbons [8, 9, 10, 11]. The Pab Formation is documented to represent thick succession in different parts of the Sulaiman Fold -Thrust Belt such as Qilla Saifullah, Loralai, Zhob and Mughal Kot [12] but poorly studied in terms of its petrography, composition, provenance and facies. The present work mainly focuses on provenance, tectonic setting and paleo-climatic conditions by carrying out modal analyses and bulk rocks geochemistry of three well exposed sections of the Formation in the western Sulaiman
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