Search

The sedimentary strata along the Permian–Triassic Boundary in the Western Salt Range of the sub‐Himalayas were analysed to gain an insight of its geological character regarding palaeoenvironments, palaeoclimate, and sequence stratigraphic attributes. The Early Triassic Mianwali Formation is dominated by shallow marine facies with transgressive phases, differentiation in facial character, and palaeowater depth among different sections. The study suggests that compared to the siliciclastic‐dominated Nammal Gorge Section, the Zaluch Nala Section is more carbonate‐dominated, representing algal‐laminated limestones, dolomitic marls, and siliciclastics – mainly restricted to the Mittiwali Member. There is a general decrease in ammonoids and increase in thickness from east to west, that is believed to be due to algal‐induced rapid sedimentation in the shallow marine environments as compared to deeper marine in the east. The Mianwali Formation has been deposited in two transgressive systems tracts, two highstand systems tracts, and one falling‐stage regressive systems tract. Two flooding surfaces, one each in the Mittiwali and Narmia members, have been recognized. The maximum regressive surfaces at the bottom (with the Chhidru Formation) and top (with the Tredian Formation) mark second‐order eustatic falls. The study also advocates for existence of a low‐energy platform in the temperate waters of the Palaeo‐Tethys. The sediments have similarities with various sections of Gondwanaland having the same trend of shallow marine facies and presence of algal‐laminated deposits. In the Middle Triassic, the gradual loss of sediment binding organisms shifted the low‐energy meandering patterns to high‐energy braided systems. [ABSTRACT FROM AUTHOR]

The southeast Hazara forms a part of Himalayan fold and thrust belt of Pakistan. The study area is covered by Mesozoic-Cenozoic age rocks that have undergone severe deformation and is characterized by the formation of complex fold and thrust assemblages. The structures include northwest and southeast verging thrust systems with associated folds. Two deformational events separate the structures in the area. The structures in the northwestern quadrant display southeast facing direction whereas the southeastern quadrant is dominated by structures that dip towards southeast. The general trend of the structures is northeast- southwest and that attributes to the northwest-southeast contractile deformation. The trend of the structures depicts that stresses were directed from northwest. The folds are found to be tight to overturned and the cores of the folds are usually occupied by competent Samana Suk Formation. The organic rich horizons were observedin the field within the Formation, the TOC of which was calculated as 0.28%. Microfacies analysis reveals well sorted and well-rounded ooidal-peloidal grainstones and packstones as well as dolomitized and fractured wackestones and mudstones. The diagenetic signatures include fracturing and dolomitization depicting its source and reservoir quality for a hydrocarbon prospect. [ABSTRACT FROM AUTHOR]