Petrology and Geochemistry of the Late Cretaceous Pab Formation, Western Sulaiman Fold- Thrust- Belt, Pakistan: Implications for Provenance and Paleo-Weathering

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.

Provenance of the Late Cretaceous Pab Formation, Sulaiman fold‐thrust belt, Pakistan: Insight from the detrital zircon U–Pb geochronology and sandstone petrography

“…However, the possibility from the Rajmahal traps cannot be excluded. The previous petrographic studies of the Pab Formation in the adjacent areas also showing the similar provenance as recycled orogen and craton interior, which supports our interpretation (Figure 5g,h) (Ahmed et al, 2021; Umar et al, 2014). The recycled orogen provenance might be from low‐grade metamorphic terrane and acidic igneous provenance.…”

“…To assess the paleogeographic reconstruction of the Indian Plate during the Late Cretaceous time along its western margin requires provenance information. This information is mainly derived from the petrographic data of the sandstones (Ahmed, Kasi, Mohibullah, & Manan, 2021; Khan, Ahmad, Arif, & Ali, 2016; Umar et al, 2014; Umar, Khan, Kelling, & Kassi, 2011). However, in the last three decades, an advancement in the U–Pb dating of the detrital zircons has become a widely applied tool in tracing the provenance (Armstrong‐Altrin, Ramos‐Vázquez, Hermenegildo‐Ruiz, & Madhavaraju, 2021; Awais et al, 2021; Baral et al, 2019; Cai, Ding, & Yue, 2011; Chen et al, 2020; Ding et al, 2016; Qasim et al, 2021; Qasim et al, 2020; Qasim et al, 2018; Ramos‐Vázquez & Armstrong‐Altrin, 2021).…”

“…The detrital zircon U–Pb dating provides in‐depth information about provenance, where multiple terranes feed the depositional basin (DeCelles et al, 2004). The Late Cretaceous stratigraphic sequence along the western margin of the Indian Plate has been studied in detail in terms of petrography and lithostratigraphy (Ahmed et al, 2021; Khan et al, 2016; Umar et al, 2014; Umar et al, 2011). However, the U–Pb dating of detrital zircon has not been applied until now.…”