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This investigation resulted in the biostratigraphic framework of the Upper Palaeocene–Lower Eocene rocks from the Upper Indus Basin, Pakistan, Eastern Tethys. The Patala Formation of the Chinjana Nala, Surghar Range of the Upper Indus Basin, was selected for this purpose. Lithologically, the Patala Formation is composed of shale and limestone interbeds. Three different fossil groups – smaller benthic foraminifera, planktic foraminifera, and calcareous nanno‐planktons – are used to establish a biostratigraphic framework for the Patala Formation. The biozones recognized in this study include: (a) bathyal benthic biozones, BB1 and BB2 of the Late Palaeocene and Early Eocene, respectively; (b) planktic biozones, P4 and P5 of the Late Palaeocene, while E1 and E2 of the Early Eocene; and (c) Calcareous Nanno‐planktons biozones: the NP9, which is further divided into NP9a and NP9b of the Late Palaeocene and Early Eocene, respectively. These biozones have been integrated to identify the Palaeocene–Eocene (P–E) boundary interval by applying widely used biostratigraphic criteria (i.e., Rhomboaster‐Discoaster [RD]‐assemblage of calcareous nanno‐planktons). In this study, we have considered the lithological interval between ChN/TP‐16 and ChN/TP‐17 as a marker horizon for the P–E boundary interval, which provided a basis for the correlation of locally established biozones with those established Tethys wide, that is, Pak‐DIV to part of Pak‐DVI correlated to SRX‐1 and SRX‐2, which are equivalent to BB1, P4, P5, and NP9a. Similarly, parts of the Pak‐DVI and Pak‐DVII are correlated to SRX‐3, which are equivalent to BB2, E1, E2, and NP9b within the study. [ABSTRACT FROM AUTHOR]

This article describes a study which examined the microfacies and depositional environments of the Margalla Hill Limestone from the Kohala-Bala area in Haripur in Hazara, Pakistan. The Margalla Hill Limestone is characterized by a wide variety of faunal and floral assemblages. The microfacies identified include Miliolid Lockhartia Mud-Wackstone Microfacies, Nummulitic Wack-Packstone Microfacies and Benthic Foraminiferal Wack-Packstone Microfacies.

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 Palaeocene–Eocene boundary (PEB) interval has been recognized in the Patala Formation, Nammal Gorge Section, Pakistan using lithostratigraphy, stable carbon isotope stratigraphy and integrated biostratigraphy. Four distinct lithological units are identified in the Patala Formation in stratigraphic order from bottom to top; unit‐1 to unit‐4. The top of unit‐3 hosts three closely spaced unconformities demarcated as U1, U2, and U3. The PEB interval is represented by a negative shift of 1.61‰ in δ13CV‐PDB representing the carbon isotopic excursion (CIE) in unit‐2. Based on the encountered foraminifera, dinocysts, and calcareous nannoplanktons, the following biozones are identified across the PEB; two larger benthonic foraminiferal (LBF) zones (SBZ4 and SBZ5), the zonal boundary slightly postdating the CIE, two smaller benthonic foraminiferal zones (BB1 and BB2), three planktonic foraminiferal zones (P4/P5 + E1), four dinocysts zones (Pak‐DV, Pak‐DVI, Pak‐DVII, Pak‐DVIII), and two calcareous nannoplankton subzones (NP9a and NP9b). The following protist, dinocyst and calcareous nannoplanktons encountered in the studied interval advocates for the placement of the possible PEB at the level between samples NAM‐SH‐07 and 08; 1—presence of the smaller benthonic foraminifera Angulogavelinella avnimelechi diagnostic of the base of the CIE and the benthonic extinction event (BEE) Tethys wide, 2—presence of the cosmopolitan and the PEB diagnostic dinocyst species 'Axiodinium augustum', 3—presence of the PEB diagnostic Rhomboaster‐Discoaster calcareous nannoplankton assemblage. The LBF species Alveolina vredenburgi [a marker species of the Larger Foraminiferal Turnover (LFT) associated with the Palaeocene Eocene Thermal Maximum (PETM) and PEB in western Tethys] occurs slightly above the onset of the CIE. Previously reported compositional change in the LBF assemblage from the Salt Range [i.e. the replacement of the Palaeocene orbitoidiform LBF (Setia and Orbitosiphon) by the Eocene LBF (Orthophragminids, Alveolina, Nummulites and Assilina)] also postdates the PEB interval here. The late appearance of Alveolina vredenburgi and the compositional change in the LBF after the onset of the CIE are attributed to the facies variation across the PEB reflecting fluctuating depositional environment due to the active tectonic across this interval. This fluctuation is evident from the smaller benthonic and planktonic foraminiferal dominating assemblages in unit‐2 representing bathyal settings followed by LBF dominating unit‐3 representing shallow carbonate platform settings. The change in LBF assemblage closely resembles the well‐known LFT associated with the PETM as well as the carbonate platform stage III and the PEB reported from other Tethyan sections. [ABSTRACT FROM AUTHOR]

The carbonate factories of the tropical to sub-tropical regions characterize a number of facies, attributable to biological and oceanographic variables. For this purpose, the Middle Jurassic carbonate rock unit (Samana Suk Formation) of the Upper Indus Basin of Pakistan was studied to understand the various Tethyan platform attributes. Four sections from Hazara area were chosen which were also compared with a section from the Nizampur Basin. The resultant microfacies were placed in their paleoenvironmental settings to reveal the facies distribution and geometry of the platform. The platform represents a gently dipping ramp, dominated by peloidal–bioclastic–ooidal grainstones and peloidal lime mudstones. The allochems and fauna show some contrasting signatures regarding paleoclimate. These microfacies infer about existence of a relatively extended tropical climatic belt in the paleo Tethys during the Middle Jurassic. The notable presence of planktonic lime mudstone facies corresponds with global marine transgression, occurring in the middle of rock unit. The nature of ooids and types of fauna of sub-tropics to tropics advocate an extended warm climatic zone in comparison with today. The dominance of gently dipping inner-ramp shoals accompanied by lagoons to steep dipping outer-ramp planktonic lime mudstones restricted the development of least encountered middle-ramp facies. The ramp platform was struck by waves and tides of different strengths including low-middle amplitude storms and the overall absence of evaporites and primary dolostones designate a humid region as manifested by euryhaline conditions. The study has drawn paleoenvironmental and palaeoceanographic similarities with sections in Tanzania, western India, NW Iran, NW Afghanistan and Western Australia. The oceanic parameters compare with present day Trucial Coast of Persian Gulf, reflecting an almost similar nature of paleoceanography in the paleo Tethys. [ABSTRACT FROM AUTHOR]