Sedimentological framework of late Pliocene and Pleistocene alluvial deposits in the Bhittani range, Pakistan

Abstract

We measured a section along the southern limb of the Marwat Kundi anticline near the village of Malagan in northwestern Pakistan. Three major depositional systems were differentiated that were based on the sampled data from this section and on some comparisons with their lateral equivalents. The lower system, the Kargocha Formation, consists of a thick succession of mainly mudstones with intercalations of conglomeratic and sandy sheet- or ribbon-like alluvial bodies. This lower depositional system was characterized by relatively small fluvial systems. The following Marwat Formation consists mainly of very thickbedded sandstones, followed by thinner bedded sandstones in its upper parts. The thick sandstone beds represent large fluvial channel complexes that were formed by a large sandy braided river, comparable to the present-day Indus river. The thin-bedded succession represents an abandonment of this large river system and a migration of the paleo-Indus towards the east to its present-day position. Finally, the Malagan Formation is formed by terminal fluvial fans, of which its modern analogue can be found within the present-day intramontane basins.