Sedimentological and provenance analysis of the Cretaceous Moro formation Rakhi Gorge, Eastern Sulaiman Range, Pakistan

Abstract

The Cretaceous Moro Formation from the Rakhi Nala section Dera Ghazi Khan has been studied in detail to investigate the Sedimentology and provenance. This paper describes the litho-facies changes, depositional environment, and provenance analysis of the Cretaceous Moro Formation from the Rakhi Nala section, eastern Sulaiman Range. The studied Formation is 110-140 meters thick and consists mainly of fine to coarse-grained sandstone,  with minor-siltstone, mudstone (claystone, shale), and limestone. The uppermost beds of the Moro Formation are consist of sandstone with iron types of cement. Twelve lithofacies have been identified based on a petrographic investigation related to the depositional environment of the Moro Formation ranging from deltaic to marine setting (Delta Plain-Delta front). Petrographic analysis of sandstone reveals the presence of quartz both, mono-crystalline and poly-crystalline, less feldspar; heavy minerals like hematite and magnetite, and glauconite were found in negligible amounts. Detrital mineral composition shows that in Moro Formation, the sandstone shows a litharenite. Modal composition of the sandstone from the QFL diagram was Q 66% F 0.3% L 33.7% and that of the QmFLt diagram was QM, 57% F 0.23% L 43.77%. The overall average composition is Q 61.5% F 0.27% L 38.7%. A total of 37 thin-sections are studied for provenance analysis, out of which twenty-seven samples are considered as Litharenite (this shows recycled, or craton interior origin), eight Quartz arenite categories are identified and two samples are fall in the sublitharenites category (Quarts recycled source area).