Lithofacies analysis and economic mineral potential of a braided fluvial succession of NW Himalayan foreland basin Pakis
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ORIGINAL PAPER
Lithofacies analysis and economic mineral potential of a braided fluvial succession of NW Himalayan foreland basin Pakistan Abbas Ali 1,2 & Jiayong Pan 1 & Jie Yan 1 & Ahmad Nabi 1,2 Received: 13 July 2018 / Accepted: 1 February 2019 # Saudi Society for Geosciences 2019
Abstract This study has described detailed lithofacies analysis, clay mineralogy, and depositional setting, and highlighted economic mineral potential of late Miocene to Early Pliocene mid Siwalik Dhok Pathan Formation. The Siwalik fluvial sedimentary succession is 5300 m thick in the NW Himalayan foreland fold-and-thrust belt known as Surghar-Shingar Range (SSR). The middle Siwalik (Dhok Pathan Formation) typically represents cyclic alternation of massive sandstones, siltstones, mudstones, and claystones in repeated fining upward rhythm with varied thicknesses from 807 to 1540 m. Detailed sedimentological investigations resulted in the identification of seven distinct lithofacies (Gt, St, Sh, Ss, Sl, Fm, and Fl) which had been deposited by sand-dominated bed load braided fluvial system. The facies Sh is hosting detrital uraninite identified through a scanning electron microscope (SEM). X-Ray diffraction analyses revealed that kaolinite, smectite (montmorillonite and saponite), illite, vermiculite, and chlorite (clinochlore and chamosite) are the main clay mineral suits present in the formation. The morphology of clay mineral suits is indicative of weathering products or contribution from the source areas. The absence of glass shards and mineral analcimolite evidenced that these smectite group clay minerals were not derived from the devitrification of volcanic ashes. The sedimentological analysis, mineralogical composition, and paleo-flow directions revealed that these sediments had been deposited by NS fluvial system presently known as Indus River system in this area. The rare earth element concentrations of sandstone and heavy minerals laminations (black sand) show enrichment of uranium (662 ppm), thorium (1374 ppm), La (975 ppm), Ce (2831 ppm), Pr (193 ppm), Nd (746 ppm), Gd (98 ppm), and Dy (50.8 ppm), which specify good indicative economic mineral potential of the formation. Keywords Siwalik Group . Clay mineralogy . Depositional environments . Detrital uraninite . Surghar range
Introduction Lithofacies analyses are significant to know the depositional environments of the sediments as characteristic lithofacies can only be produced by particular sediment depositional environments. Sedimentary lithofacies analysis has been considered an important exploration tool for many syndepositional mineral deposits such as pollymetallic gold and base metal, uranium, and rare earth element (REE) deposits. The detailed Editorial handling: John S. Armstrong-Altrin * Jiayong Pan [email protected] 1
School of Earth Sciences, East China University of Technology, Nanchang 330013, People’s Republic of China
2
Pakistan Atomic Energy Commission, Post Box #658, Lahore, Pakistan
lithofacies analyses are helpful in predicting the favorable strata for
