Lithostratigraphy of the Kurram Group rocks along Mirali-Miran Shah road, North Waziristan Agency, NWFP, Pakistan

Abstract

This study focuses on the identification and description of a thick Mesozoic sequence exposed along Mirali-Miran Shah road in North Waziristan Agency, previously named as Kurram Group. The detailed field investigation has resulted in establishing six distinct lithostratigraphic units, ranging in age from Late Triassic to Late Cretaceous with dominant lithologies being limestone, sandstone, shale, and siltstone. The oldest rocks i.e. Triassic of the area is named as Spalga Formation. The contact between the Triassic and base of the Jurassic is marked by a thrust fault in the entire mapped area. The Jurassic rocks are represented by a thick sequence of limestone and shale, which are divisible into two formations named as Sarobi Formation and Isha Formation. These rocks are disconformably overlain by the Cretaceous sequence, which includes Chashmai Kharsai Formation, Marsi Khel Formation and Zerghar Formation. Except the Triassic, all the rock assemblages have yielded fossils of their respective age. The fauna and lithology of the area is broadly correlative with the Mesozoic rocks of Samana- Kohat area towards north and Baluchistan Province in the south.