Stratigraphy and Sedimentology of the Upper Siwalik Group, Sakhi Sarwar Area, Southern Zindapir Anticline, Sulaiman Range, Pakistan
Abstract
The Zinda Pir anticline, forming foothills east of the Fort Monro anticline, exposes the Siwalik Group along its periphery. The Siwalik Group exposed in the area includes Vihowa, Litra and Chaudhwan Formations. The Vihowa Formation consists of grey and brown sandstone and red to brownish-red siltstone. The overlying Litra Formation comprises of light-grey sandstone with subordinate brown to reddish-brown siltstone. The Chaudhwan Formation overlies Litra Formation and predominantly consists of conglomerates with ancillary interbedded pale-grey sandstone. Sedimentological studies of the upper Litra Formation reveal presence of siltstone/claystone as overbank deposits, and conglomerate, trough cross-bedded sandstone, low-angle plane-bedded sandstone and planar cross-bedded sandstone as channel deposits. Whereas the Chaudhwan Formation dominantly comprises conglomerates, deposited as diffuse gravel sheets during high flow, with minor sandstone and siltstone/claystone units. Paleocurrent analysis suggests a SSE-ward paleo-flow. The sandstones of the Litra and the Chaudhwan Formations arc texturally similar. Moderate angularity and sorting, along with high content of feldspar indicate textural immaturity of these sandstones and substantial contribution from a northern provenance. Whereas, the petromict ortho-conglomerates of the Chaudhwan Formation indicate a predominant western provenance (i.e., Fort Monro anticline).
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