Lithofacies of Bara Formation at Wadi Sawri Nala Section, Northern Laki Range, Southern Indus Basin, Pakistan

Abstract

Detailed account of Bara formation Lithofacies is carried out at Wadi Sawri Nala Section (WSNS) on basis of physical characteristics such as color, texture, lithology, sedimentary structures and contact relationship. The two hundred eighty (280) meters thick Bara Formation at (WSNS) is conglomeratic sandstone, sandstone, siltstone, shale, and mudstone succession. In Bara Formation eight Lithofacies have been recognized, these are Conglomeratic sandstone facies (Gt), Fine to coarse grained trough cross bedded sandstone facies (St), Fine to very coarse grained planar cross-bedded sandstone facies (Sp), Ripple cross laminated sandstone facies (Sr), Fine to medium grained flat bedded sandstone facies (Sh), Parallel laminated siltstone and shale facies (Fl), Massive mudstone & shale facies (Fm), Carbonaceous shale facies(C). These lithofacies show recurrent fining upward cycles. The sedimentary structures identified in Bara Formation are planar and trough cross beds, asymmetrical ripple marks, planar laminations, fissile & carbonated shale and massive mudstone. The study of these structures indicate that Bara formation was deposited in fluvial depositional system