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Early Eocene orthophragminids (Foraminifera) from the type-locality of Discocyclina ranikotensis Davies, 1927, Thal, NW Himalayas, Pakistan: insights into the orthophragminid palaeobiogeography a

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Ercan Özcan , Muhammad Hanif , Nowrad Ali & A. Osman Yücel a

Faculty of Mines, Department of Geological Engineering, İstanbul Technical University (İTU), Maslak, 34469 İstanbul, Turkey b

National Centre of Excellence in Geology, University of Peshawar, Peshawar, 25120 Khyber Pakhtunkhawa, Pakistan c

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Department of Geology, University of Peshawar, Peshawar, 25120 Khyber Pakhtunkhawa, Pakistan Published online: 18 May 2015.

To cite this article: Ercan Özcan, Muhammad Hanif, Nowrad Ali & A. Osman Yücel (2015): Early Eocene orthophragminids (Foraminifera) from the type-locality of Discocyclina ranikotensis Davies, 1927, Thal, NW Himalayas, Pakistan: insights into the orthophragminid palaeobiogeography, Geodinamica Acta, DOI: 10.1080/09853111.2015.1026795 To link to this article: http://dx.doi.org/10.1080/09853111.2015.1026795

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Geodinamica Acta, 2015 http://dx.doi.org/10.1080/09853111.2015.1026795

Early Eocene orthophragminids (Foraminifera) from the type-locality of Discocyclina ranikotensis Davies, 1927, Thal, NW Himalayas, Pakistan: insights into the orthophragminid palaeobiogeography Ercan Özcana*, Muhammad Hanifb, Nowrad Alic and A. Osman Yücela Faculty of Mines, Department of Geological Engineering, İstanbul Technical University (İTU), Maslak, 34469 İstanbul, Turkey; National Centre of Excellence in Geology, University of Peshawar, Peshawar, 25120 Khyber Pakhtunkhawa, Pakistan; cDepartment of Geology, University of Peshawar, Peshawar, 25120 Khyber Pakhtunkhawa, Pakistan a

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(Received 17 December 2014; accepted 4 March 2015) The study of isolated orthophragminid tests at the type-locality of Discocyclina ranikotensis Davies from the Patala Formation in Thal area (Upper Indus Basin, NW Pakistan) revealed new associations of genera Discocyclina Gümbel, and Orbitoclypeus Silvestri, not yet reported from eastern Tethys. We demonstrate that D. ranikotensis Davies, the species identity of which has been a subject of controversy in earlier works, is a valid species endemic at least to the IndoPakistan region. D. ranikotensis is associated with Discocyclina archiaci (Schlumberger), and very sparse Orbitoclypeus schopeni (Checchia-Rispoli), both species being key taxa for orthophragminid zonation in peri-Mediterranean Tethys. We have also identified a few discocyclinid specimens suggesting possible connection to western Tethys species D. fortisi, and a few specimens showing affinity to D. dispansa. The assemblages of orthophragminids suggest orthophragminid zone (OZ) 3 according to western Tethyan zonation scheme. The occurrence of D. archiaci extends the geographical distribution of this taxon to eastern Tethys, which hitherto was only known from peri-Mediterranean region. The typical western Tethyan asterocyclinids, nemkovellids and ribbed orbitoclypeids, first appearing at or around Paleocene/Eocene boundary (OZ 1B/2, SBZ4/5), have not been identified. Keywords: early Eocene; orthophragminids; Discocyclina ranikotensis; taxonomy; NW Himalayas; Pakistan

1. Introduction The late Paleocene to early Eocene larger benthic foraminifera (LBF) in shallow marine sediments of Tethyan Himalayas are represented by Lockhartia– Ranikothalia–Miscellanea–Daviesina communities which serve as index fossils for so called ‘Lockhartia Sea’ reaching in Asia from Tibet to southern Turkey, in Africa from Somalia to Egypt (Hottinger, 2009, 2014). The LBF assemblages of the ‘Lockhartia Sea’, an eastern Tethyan biogeographic province, have been extensively studied from Paleocene and early Eocene sediments in Pakistan, India, Tibet and Oman, although orthophragminids still remain poorly known (Afzal, Williams, Leng, Aldridge, & Stephenson, 2010; Davies, 1927; Davies & Pinfold, 1937; Eames, 1951a, 1951b; Haynes, Racey, & Whittaker, 2010; He, Zhang, Hu, & Sheng, 1976; Hottinger, 2009, 2014; Racey, 1995; Zhang, Willems, & Ding, 2013). The previous records of orthophragminids in ‘upper Paleocene’ – lower Eocene sediments in Pakistan mostly refer only to Discocyclina ranikotensis Davies, 1927, a poorly known species considered to be endemic to Tethyan Himalayas in Indo-Pakistan region, suggesting a less diverse character of eastern Tethys orthophragminids compared to those of western Tethys in this time span. *Corresponding author. Email: [email protected] © 2015 Taylor & Francis

Patala Formation or its equivalents in north Pakistan (NW Himalayas) and Sind is a key stratigraphic unit, studied extensively since early 1930s (Davies, 1927; Nuttall, 1925) for its rich LBF having a regional biostratigraphic and palaeobiogeographic significance. Many new species of ‘Lockhartia Sea’ have been described from this unit in Thal area and Salt Range in north Pakistan (Davies, 1927; Davies & Pinfold, 1937), which later became index taxa on a regional scale (Afzal et al., 2010; Haynes et al., 2010; He et al., 1976; Hottinger, 2009, 2014; Nagappa, 1959; Racey, 1995; Smout, 1954; Smout & Haque, 1956; Zhang et al., 2013). Davies (1927) noted the occurrence of orthophragminids in the Patala Formation (‘upper Ranikot beds’ of Davies, 1927) from the Thal area and erected D. ranikotensis based on its supposedly larger embryon than that of D. archiaci, which according to him, had been only known from Europe. Subsequently, this species has been widely adopted in late Paleocene or early Eocene deposits in Pakistan, while it has also been rarely reported in Italy, Slovakia, India and Oman (Köhler, 1967; Racey, 1995; Schweighauser, 1953; Sigal, Singh, & Lys, 1971). The validity of D. ranikotensis, however, has been questioned by some LBF experts, arguing that original description of species, that backs to late 1930s, was poor and also later identifications are contradicting to each other (Less, 1987; Neumann, 1958).


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In previous taxonomic and biostratigraphic studies, the contradictory stratigraphic ranges of D. ranikotensis and common confusion of this species with Paleocene orbitoidiform taxa are noted. This is particularly because the species identity of D. ranikotensis is virtually unknown, and also almost all previous records are based on either the vertical sections of megalospheric individuals or equatorial sections of microspheric forms not justifying the species assignment. Moreover, the reports of this species in Paleocene beds (Hangu and Lockhart formations and lower part of Patala Formation) in association with typical Paleocene orbitoidiform taxa (e.g. Orbitosiphon and Setia) should be considered with caution after Ferrández-Cañadell (2002), who has demonstrated that orthophragminids do not occur in Paleocene of Salt Range. Consequently, species definitions for the orthophragminid taxa, thought to be endemic to Indo-Pakistan region, have yet to be clearly established. This has further implications that the proposed LBF diversity and distribution models by Hottinger (2014) in ‘Lockhartia Sea’ are incomplete in the absence of detailed taxonomical works on orthophragminids, closely associated with nummulitids and rotaliids in eastern Tethys. In this paper, we present our results on the taxonomy, biostratigraphy and palaeobiogeography of orthophragminids from a well-known locality for the LBF of the Patala Formation at Thal, NW Pakistan, which is the type locality of D. ranikotensis and some index rotaliid and nummulitid foraminifera of ‘Lockhartia Sea’. The main emphasis is on the description of the orthophragminids and their relationship to those well-studied coeval taxa from western Tethyan platforms, particularly from Turkey. For this, some specimens of D. archiaci and O. schopeni from several early Eocene sections in Turkey, which represent the depositional setting at the northern Tethyan margin during the early Eocene, are also illustrated and discussed. Moreover, considering the common confusion of orthophragminids with Paleocene orbitoidiform foraminifera (e.g. Setia and Orbitosiphon), we illustrate and compare the vertical sections of these foraminifera from late Paleocene Lockhart Limestone in Salt Range, N Pakistan. The identified taxa are then used to discuss the early Eocene orthophragminid palaeobiogeography. 2. Geological setting and early Palaeogene Stratigraphy in Thal area The NW Himalayas in NW Pakistan represents a collisional zone resulted from the India-Afghan collision during late Paleocene and early Eocene times (Beck et al., 1995; Kazmi & Abbasi, 2008; Kazmi & Rana, 1982; Khan & Abbas, 2011) (Figure 1). In this area, a wide range of Neo-Tethyan accretionary prism and trench complexes, volcanic-arc related sediments, olistostromes (Kahi mélange), ophiolites (Waziristan ophiolite) and Palaeogene sedimentary units are exposed near the

Afghanistan-Pakistan border (Beck et al., 1995; Kazmi & Rana, 1982; Khan & Abbas, 2011; Khan, Abbasi, Qureshi, & Rahim, 2003) (Figure 2). Kahi mélange, which was emplaced onto the passive Indian margin prior to the deposition of late Paleocene–early Eocene sediments, was interpreted to serve the earliest signature of India-Afghan collision (Beck et al., 1995). This view, however, was challenged by Khan et al. (2003) arguing that lack of this unconformity in the shelf sequence, formerly deposited at the NW margin of the Indian Plate, would suggest that this tectonic event was local, probably related with ophiolite obduction rather than IndiaEurasia collision. Following the ophiolite obduction in late Cretaceous, N Pakistan became the site of widespread deposition of dominantly late Paleocene to early Eocene shallow marine sediments of Lockhart, Patala and Panoba formations (Figure 1). The field relations of obduction-related thrust sheets derived from the various parts of continental shelf-ocean floor transition, and shallow marine Tertiary cover units are well observed in Thal area, to the west of Kohat Plateau (Figure 2). The Palaeogene sequence at Thal is divided into the following units: (1) Patala Formation (‘upper Ranikot beds’ of Davies, 1927): this unit comprises an inter-bedded sequence of marl, shale, siltstones and argillaceous limestones, and is interpreted to have been deposited in a variety of depositional environments ranging from shallow marine inner shelf to open marine (Afzal & Daniels, 1991; Afzal, Williams, & Aldridge, 2009; Davies & Pinfold, 1937; Hanif, Ali, & Afridi, 2013; Köthe, Khan, & Ashraf, 1988). Patala Formation, originally described from Salt Range in Pakistan (Davies & Pinfold, 1937), is widely distributed in fold- and thrust-belt in Upper Indus Basin in north Pakistan (Figure 1) and is richly fossiliferous with age-diagnostic LBF. In Thal area, a ca. 400-mthick shallow marine succession sandwiched between the Kahi mélange and Kohat Formation corresponds to the Patala Formation of late Paleocene to early Eocene age. Patala Formation was differentiated to several units by Davies (1927) (Figure 3), who recognised the ‘lower and upper Ranikot beds’, and subdivided the ‘upper Ranikot beds’ into vaguely defined four ‘zones’, based on the lithology and fossil content. The uppermost zone (zone 4 = uppermost Ranikot beds), ca. 12 m thick, is the most distinct as it is characterised exclusively by the common occurrence of LBF. Beck et al. (1995) proposed that the thick sedimentary succession stacked between the Kahi mélange and Kohat Formation corresponds to the Patala (Ranikot) Formation, which is equivalent to the lower and upper Ranikot beds of Davies (1927). In the present work, studied portion of the Patala Formation cannot precisely be correlated to the sedimentary succession of Davies (1927) because of very thick and monotonous nature of the fine clastics above the Kahi mélange and lack of significant stratigraphic markers to place the boundary between lower and upper Ranikot beds and also between the ‘zones’ of Davies. In the stratigraphic


Geodinamica Acta nomenclature of Palaeogene sediments, we follow Kazmi & Abbasi (2008), who presented the most detailed stratigraphic framework of Tertiary units in Pakistan. These authors suggested that ‘upper Ranikot beds’ of Davies (1927) is equivalent of Patala Formation, although some earlier works adopted ‘Panoba Formation’ for the same clastic succession in Thal area (Khan et al., 2003). (2) Kohat Formation: Patala Formation is unconformably overlain by the nodular and marly limestones of Kohat Formation, referred to as ‘Laki Beds’ by Davies (1927). This is a shallow marine unit, ca. 15 m in thickness, containing a rich alveolinid and nummulitid assemblage marking the last episodes of marine sedimentation in Kohat area. The Miocene molasse sediments of the Kamlial Formation unconformably overlie the Kohat Formation (Figure 3). The late Ypresian age assignment for this unit given by Beck et al. (1995) is based on the planktonic foraminifera that indicate P9 Zone. Considering the earlier ages given to this unit by LBF and mollusks, Afzal et al. (2009) have assigned an age of early to middle Lutetian to Kohat Formation based on the LBF indicative of SBZ 14–16 zones. 3. Historical review; foraminiferal compositions, age of the Patala Formation and their significance in regional geology Davies (1927) erected D. ranikotensis from the ‘upper Ranikot beds’ in Thal for large, flat discocyclinid specimens with a prominent central umbo and granules (piles) evenly distributed at the surface of the discoidal test. The orthophragminid assemblages in these beds are regarded to be monospecific, associating with agediagnostic LBF such as Ranikothalia, Miscellanea, Lockhartia, Nummulites, Assilina and Alveolina. Davies, however, has figured only the exterior of D. ranikotensis depicting the well-developed central umbo and granules, a vertical section of a microspheric form and an oblique section illustrating the features of pillars, but not any equatorial sections. A single hand-drawn illustration of the embryon (Davies, 1927; Figure 4) shows a transitional embryonic configuration between trybliolepidine and umbilicolepidine types while development of adauxiliary and annular chambers were not illustrated (Figure 12). Having noticed that this species has affinities with D. archiaci (Schlumberger, 1903), only know in Europe at that time, Davies concluded that D. ranikotensis is different from D. archiaci by having a much larger embryon (deuteroconch), reported to be about 560–660 μm for deuteroconch and 260 μm for protoconch. This species was reported to be associated with such foraminiferal taxa as N. globulus, N. nuttali var. kohaticus, N. thalicus, N. thalicus var. gwyne, Assilina ranikoti, Operculina sindensis, O. cf. canalifera, Dictyoconoides conditi, D. newboldi, D. haimei and Alveolina oblonga. Based on the above shallow marine assemblage, Davies (1927) has assigned a Landenian (equivalent to Thanetian) age to ‘uppermost Ranikot

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beds’. Davies & Pinfold (1937) also figured only an external view of this species from Patala Formation in Salt Range, suggesting that D. ranikotensis has a wide stratigraphic range based on its occurrence in Dhak Pass beds (Hangu Formation), Khairabad Limestone (Lockhart Limestone) and Patala and Nammal formations. This suggests a wide stratigraphic range of this species from Paleocene to early Eocene and also implies the co-occurrence of D. ranikotensis with Paleocene orbitoidiform foraminifera such as Orbitosiphon punjabensis and Setia tibetica. Consequently, D. ranikotensis has recurrently been reported from various stratigraphic levels ranging in age from late Paleocene to early middle Eocene in Pakistan, Iran, Italy and Slovakia. It was reported from late Paleocene (Afzal, Khan, Khan, Alam, & Jalal, 2005; Ahmad, 2010; Ahmad et al., 2014; Baruah & Das, 2007; Imraz, 2013; Latif, 1976; Sameeni, İmtiaz, Saleem, Haneef, & Naz, 2014; Sameeni, Nazir, Abdul-Karim, & Naz, 2009; Sigal et al., 1971; Yaseen, Rajpar, Munir, Roohi, & Rehman, 2011), late Paleocene to early Eocene (Afzal, 2010; Afzal et al., 2010; Butt, 1991; Hanif et al., 2013; Nagappa, 1959; Sameeni et al., 2014; Shafique, 2001; Weiss, 1993), early Eocene (Babazadeh, 2008, 2011; Schweighauzer, 1953), from late Ypresian- early Lutetian (Mirza, Sameeni, Munir, & Yasin, 2005) and Middle Eocene (Köhler, 1967) (Figure 4). According to Beck et al. (1995), who provided the only planktonic foraminiferal data in the same area with our present work, Patala Formation covers planktonic foraminiferal P5 and P6 zones, implying a late Thanetian–early Eocene age, which is in accordance with the ages obtained from the Patala Formation in Salt Range and Kohat area (Afzal & Butt, 2000; Afzal & Daniels, 1991; Afzal et al., 2009). The calcareous nannofossils identified by Köthe et al. (1988) from Patala Formation in Salt Range and Kohat area suggest Thanetian–early Eocene age based on the NP8–12 zones. With respect to LBF, previous studies identified SBZ 4–6 in Kohat area (Sameeni, Haneef, Rehman, & Lipps, 2009), SBZ4/5 in Surghar Range (Sameeni et al., 2014) and SBZ 4–9 in Kohat area and Salt Range (Afzal et al., 2009) that would indicate a Thanetian–early Eocene age for the Patala Formation. A late Thanetian–early Eocene age for the Patala Formation is also supported by the revised stratigraphic distribution of rotaliid species, such as Lockhartia haimei (SBZ 4–7), Lockhartia conditi (SBZ 4–8), Rotalia newboldi (SBZ 6–8) and miscellanids by Hottiger (2009, 2014). The LBF in the early Palaeogene shallow-marine sediments of Himalayan belt play an important role in understanding the distribution of foraminiferal communities along the northern margin of Indian Plate, and their distribution and interaction in Tethys (Adams, 1983; Afzal et al., 2010; Haynes et al., 2010; Hottinger, 2009, 2014; Zhang et al., 2013). It is generally agreed that LBF assemblages from Indo-Pakistan (eastern Tethys) and peri-Mediterranean regions (western Tethys) differ partly from each other across the P/E boundary, resulting


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in the formation of bioprovinces across the Tethys (Afzal et al., 2010; Hottinger, 1998, 2009, 2014). The principal building stones in the establishment of these provinces constitute nummulitid and rotaliid foraminifera while the distribution and interaction of orthophragminids are virtually not known. It is only upper Paleocene time slice for which we have adequate information to propose that orbitoidiform LBF replace the orthophragminids, which are lacking in Paleocene sediments in some sections in Salt Range and in Tibet (Ferrández-Cañadell, 2002; Zhang et al., 2013). LBF assemblages from the Paleocene and Eocene shallow-marine sediments have also been widely adopted to constrain the age of India–Asia collision by recording the transition from marine to continental facies and regional marine transgressions related to the tectonic phases along the passive margin of Indian Plate (Afzal et al., 2010; Beck et al., 1995; Gaetani et al., 1983; Green, Searle, Corfield, & Corfield, 2008; Najman et al., 2010; Rowley, 1996; Zhang, Willems, Ding, Grafe, & Appel, 2012; Zhu, Kidd, Rowley, Currie, & Shafique, 2005). However, interpretation of fossil data from different shallow-marine localities in Pakistan and Tibet is contradicting because of different approaches in evaluating the data in connection with the tectonic events. A remarkable example for this controversy is the interpretation of LBF record in Patala Formation in the present study area in Thal. Beck et al. (1995) have interpreted the unconformity between Upper Cretaceous Kahi mélange and Ranikot series (Patala Formation) (Figure 3) to define the initial collision between the Indian Craton and trans-Himalayan arc in upper Paleocene. This view, however, has been challenged by Khan et al. (2003) arguing that this tectonic event was local, probably related with ophiolite obduction rather than India-Eurasia collision. Recently, Afzal et al. (2009) have proposed that the closure of Tethys in Pakistan was initiated during the early Lutetian rather than early Eocene and was completed by the Priabonian by using foraminiferal and other fossil data from Indus Basin. 4. Materials and methods THAL Section is situated in the northwestern part of Upper Indus Basin, to the south of Thal in NW Pakistan (Figures 1, 25). The Section, 90 m in thickness, exposes highly fossiliferous shale-siltstone beds of the Patala Formation along the eastern bank of Ishkalai River (33°20′22″ N, 70°34′2.5″ E/33°20′25.86″ N, 70°34′ 16.08″ E), where only upper portion of this unit is exposed. Seventeen samples (THAL.1–17) have been collected from the Patala Formation, and ten of them (THAL.1, 2, 3, 8, 10, 11, 12, 14, 15, 16) yielded reasonable number of orthophragminids. The position of samples and the LBF composition are shown in Figure 6. In addition, two spot samples, THAL.A and THAL.B have been collected from the Patala Formation in the same area; THAL.A is from a narrow exposure along the

Ishkalai River near Thal Fort (33°21′53.05″ N, 70°33′ 53.40″ E) and THAL.B is at a close proximity to the THAL Section (33°20′45.40″ N, 70°34′9.00″ E). The stratigraphic position of sample THAL.A in the frame of stratigraphic development of Patala Formation cannot precisely be marked, although it can tentatively be correlated to the lower part of the THAL Section, whereas sample THAL.B is from the upper part of the Patala Formation. This study is based on the investigation of individual specimens extracted from the shale, marl and argillaceous limestones. The oriented sections of megalospheric and microspheric specimens (A and B forms, respectively) have been prepared through their equatorial layers because the most important taxonomic and evolutionary parameters are observed in this part of the test (Ferrández-Cañadell, 1998a; Less, 1987; Neumann, 1958; Portnaya, 1974). This requires the grinding of the lateral parts of the free test on both sides of the equatorial layer by a fine grinding paper to a certain level in the equatorial layer to obtain a section exposing the embryon and surrounding annular chambers. The biometric measurements and counts were executed on the equatorial layer of megalospheric specimens. Using the terminology proposed by Less (1987, 1998), eight measurements (in μm) and counts and some qualitative data from 458 specimens were used to characterise the taxa, as illustrated in Figure 7 and tabulated in Table 1. These measurements and counts are: P and D, outer diameter of the protoconch and deuteroconch perpendicular to their common axis; A, number of adauxiliary chamberlets (adc); H and W, height and width of the adc; n .5, number of annuli within a .5 mm distance measured from the deuteroconch along the axis of the embryon; and h and w, height and width of the equatorial chamberlets around the peripheral part of the equatorial layer. In addition, more than 50 vertical and equatorial sections of megalospheric and microspheric forms have been prepared to complement the identifications. The biometry of orthophragminids from spot samples THAL.A and B is also integrated into Table 1. We also illustrate some specimens of D. archiaci and O. schopeni from two lower Eocene shallow marine sections in Turkey to compare the test features observed in equatorial and vertical sections with Thal specimens. The foraminiferal assemblages in these samples, ERE.24 and 396, collected in Karamürsel, Kocaeli (NW Turkey) (Özcan, Okay, Özcan, Hakyemez, & Özkan-Altıner, 2012) and Sarıyaka, Kırıkkale (C Turkey) (Gül et al., 2012; Özcan et al., 2013) areas, respectively, the characteristic early Eocene orthophragminid assemblages of the western Tethyan platforms. In addition, considering the confusion of Paleocene orbitoidiform forms with orthophragminids in the previous works, we also illustrate and compare the vertical sections of Orbitosiphon and Setia with the orthophragminids from Thal. Sub-species are determined according to the biometrical limits of subspecies as applied in previous


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Figure 1. Distribution of (late) Paleocene to (early) Eocene shallow-marine sediments in north Pakistan, and position of the study area in NW Himalayas. Thal is located in fold-and-thrust belt to the south of Main Boundary Thrust (MBT). MKT – Main Karakorum Thrust, MMT – Main Mantle Thrust, SRT – Salt Range Thrust (Synthesised from Kazmi & Rana, 1982).

biometric studies (Less, 1998; Özcan, Less, & Kertész, 2007; Özcan et al., 2010). No subspecies is determined in case of single specimen. If the number of specimens is two or three, the subspecies is determined as ‘cf.’. If the number of specimens is four or more, and the Dmean value of the studied population is closer to the biometrical limit of the given subspecies than 1 s.e. of Dmean, we use an intermediate denomination between the two neighbouring subspecies. In these cases we adopt Drooger (1993) in using the notation exemplum intercentrale (abbreviated as ex. interc.). All specimens are deposited in the Özcan collection in the Department of Geological Engineering, İstanbul Technical University (İstanbul). 5. Test morphology of the Tethyan orthophragminids and their distribution in late Paleocene and early Eocene in western Tethys Orthophragminids are bilamellar, perforate foraminifera characterised by a discoidal, lenticular test with an equatorial layer consisting of cyclically arranged equatorial chambers and lateral layers composed of lateral chambers and pillars on either side of the equatorial layer (Figure 7(a) and (b)). Externally, the test surface is either smooth, occasionally with an inflated central part, or it is characterised by radially developed ribs. Dimorphism is reflected in the size of the test, which is larger in sexually produced microspheric specimens than in asexually produced megalospheric forms. The diameter of megalospheric specimens is ~1 cm or less, while microspheric specimens may reach up to several centimetres. The equatorial chambers are divided into

chamberlets of different shapes as observed in equatorial sections. The western Tethyan orthophragminids include four genera: Discocyclina Gümbel, 1870, Nemkovella Less, 1987, Orbitoclypeus Silvestri, 1907 and Asterocyclina Gümbel, 1870, classified under the families Discocyclinidae Galloway, 1928, and Orbitoclypeidae Brönnimann, 1946 (Brönnimann, 1945). The Discocyclinidae and Orbitoclypeidae are distinguished by their different microspheric juvenaria only observable in equatorial section (Figure 7(f) and (g); Less, 1987; Ferràndez-Cañadell & Serra-Kiel, 1992; Ferràndez-Cañadell, 1998a, 1998b). The embryonic apparatus (hereafter abbreviated to ‘embryon’) of the megalospheric specimens consists of a spherical to subspherical protoconch (P) enclosed more or less by the second chamber, the deuteroconch (Figure 7(c) and (e)). Both chambers communicate to each other through a large single protoconchal stolon (ps). Based on the relationship between both chambers in equatorial sections, about ten configurations are used in the description of the embryon (Less, 1987; Figure 8). The first annulus includes those chamberlets (ch) developed simultaneously around the deuteroconch; adc and principal auxiliary chamberlets (pac) arise from the junction of P and D (Figure 7(d) and (e)). The communication between the chamberlets of the same annulus is through the annular stolons (as) in Discocyclina, although such stolons do not exist in other genera. The radial stolons (rs) are positioned along the septum (s) of the distal chamberlet walls for communication between the successive annular chambers. The western Tethyan orthophragminid genera (Discocyclina, Nemkovella, Orbitoclypeus and

26 30 44 6 27 33 34 33 25 19 33 5 2 6 12 3 21 21 8 2 17 23 13 4 1 1 1 1 2 4 1

THAL.2 THAL.3 THAL.12 THAL.15 THAL.16 THAL.B THAL.1 THAL.10 THAL.8 THAL.11 THAL.A THAL.1 THAL.2 THAL.3 THAL.8 THAL.10 THAL.11 THAL.12 THAL.14 THAL.15 THAL.16 THAL.A THAL.B THAL.A THAL.3 THAL.8 THAL.12 THAL.B THAL.16 THAL.B THAL.A

650–950 630–770

220–380 200–340 180–380 210–320 205–410 200–390 210–370 220–410 245–410 210–400 205–395 440–660 440–440 495–795 400–940 400–440 400–770 430–760 500–725 610–650 480–950 400–580 450–665 110–190

Range

287.3 ± 8.82 261.0 ± 6.67 289.3 ± 7.25 256.7 ± 16.3 285.6 ± 11.4 284.6 ± 9.03 297.0 ± 7.33 302.3 ± 8.24 315.8 ± 9.42 318.4 ± 10.2 314.4 ± 9.27 524.0 ± 32.5 440.0 ± 00.0 648.3 ± 42.0 537.9 ± 39.4 420.0 ± 9.43 533.6 ± 17.8 595.0 ± 20.9 603.1 ± 22.6 630.0 ± 14.1 639.7 ± 32.0 464.4 ± 12.3 573.6 ± 21.0 167.5 ± 16.6 165.0 175.0 170.0 190.0 800.0 ± 106.7 702.5 ± 24.84 200.0

Mean±s.e

295–550 250–310

110–220 100–165 100–225 105–165 90–230 105–215 90–215 100–230 115–230 110–290 105–200 170–270 240–250 230–365 150–390 190–210 190–460 200–320 230–300 270–290 200–320 150–325 150–325 65–115

Range 150.0 128.6 152.1 125.8 150.0 151.2 151.1 157.9 164.4 169.4 150.6 225.0 245.0 289.0 255.0 200.0 249.5 252.7 266.0 280.0 265.0 221.5 227.7 93.8 95.0 100.0 90.0 110.0 422.5 283.3 100.0

Mean

P

D

33–55 31–43 38–56 10–13 16 14 15 15 >51 57–62 21

18–29 16–28 17–31 23–28 20–25 20–36 14–32 22–31 21–33 17–31 20–29 34–50 38 49–55 32–64 31–40 33–48 31–54 35–53

A Range

Number

35–55 30–60 35–60 30–50 30–50 25–70 25–55 30–50 25–60 35–60 30–55 30–95 45–70 40–75 30–80 35–50 25–80 45–75 30–85 40–75 35–100 35–75 30–95 30–50 35–40 20–40 30–35 35 65–90 55–90 30–35

H Range

Height

25–50 20–45 25–45 25–30 25–40 25–50 25–45 25–35 25–50 25–45 25–45 25–50 25–50 25–60 25–50 25–50 25–50 30–50 25–65 25–55 25–50 30–55 25–55 25–40 25–35 25–40 25–30 25–35 30–50 30–55 20–30

w Range

Width

Adauxiliary chamberlets

12–17 13–18 11–20 14–16 10–18 13–19 13–17 13–21 11–18 12–18 11–17 8–13 15 8–9 8–14 13–15 9–12 7–12 8–9 8 7–11 8–12 7–12 16–23 17 16 20 17 7–9 7–11 17

n .5 Range

Annuli/.5mm

25–115 25–90 25–60 35–110 25–50 30–70 30–50 30–65 30–75 30–40 45–120 35–65 35–50 35–70 40–100 30–35 35–85 35–85 50–110 70–80 40–75 40–50 40–80 30–60 35–45 30–45 30–40 30–40 55–105 65–80 40–50

h Range

Height

25–50 25–50 20–60 25–35 20–30 20–40 25–40 25–45 25–35 25–40 20–45 20–50 25–35 25–35 25–45 25–35 25–45 20–45 25–40 25–35 25–30 25–40 25–40 25–35 20–25 25–45 20–35 20–30 25–40 20–50 25–30

w Range

Width

Equatorial chamberlets

Notes: For the illustration and explanation of the parameters see Figure 7(c). N denotes the number of specimens studied in the sample.

N

Protoconch

Deuteroconch

Outer cross dia. of the embryon

Statistical data of orthophragminids from Patala Formation.

Sample

Table 1.


Orbitoclypeus schopeni

D. aff. fortisi

D. dispansa ex. interc. taurica-broennimanni D. dispansa

D. ranikotensis

D. a. ex. interc. staroseliensis-bakhchisaraiensis

D. a. ex. interc. bakhchisaraiensis-staroseliensis

Discocyclina archiaci bakhchisaraiensis

Species/Subspecies

6 E. Özcan et al.


Geodinamica Acta Asterocyclina) comprise more than 50 species in the Thanetian–Priabonian. Of these, 15 occur in the Thanetian—early Eocene from orthophragminid zone (OZ) 1A to OZ 4 (Figure 9). In western Tethyan platforms, Thanetian orthophragminids are represented by four species: Discocyclina seunesi Douvillé, D. tenuis Douvillé, Orbitoclypeus schopeni (Checchia-Rispoli) and O. multiplicatus (Gümbel) (Figure 9). A significant diversification in orthophragminids at or around the P/E boundary is marked by the first appearance of nemkovellids, asterocyclinids and ribbed orbitoclypeids. The characteristic species are Nemkovella stockari Less and Özcan, N. evae Less, Orbitoclypeus munieri (Schlumberger), O. bayani (Munier-Chalmas) and Asterocyclina taramellii (Munier-Chalmas). The last three species are characterised by the presence of external ribs, a morphologic feature not observed in Thanetian orthophragminids. Species such as D. archiaci, D. dispansa and D. furoni first appear almost simultaneously in OZ 3. Of these, D. archiaci is the fastest evolving and most abundant species in western Tethyan platforms and it is a key taxon in assigning orthophragminid assemblages to the OZ zones in the early Eocene. 6. Taxonomy We present a detailed synonym list only for D. archiaci and D. ranikotensis, the most common orthophragminid taxa in Patala Formation in Thal. Only the original publications for the rare taxa, such as D. dispansa, O. schopeni have been cited. In the classification orthophragminids, we follow Less (1987, 1998), updated by Less, Özcan, Báldi-Beke, & Kollányi (2007) and Özcan, Less, & Kertész (2007). Order Foraminiferida Eichwald, 1830 Family Discocyclinidae Galloway, 1928 Genus Discocyclina Gümbel, 1870 Type species: Orbitolites pratti Michelin, 1846 Discocyclina archiaci (Schlumberger, 1903) Diagnosis. D. archiaci is an unribbed species having semi-nephrolepidine to trybliolepidine embryons in the older members (D. archiaci bakhchisaraiensis and D. archiaci staroseliensis) and trybliolepidine and umbilicolepidine embryons in the advanced members (D. archiaci bartholomei) (Figure 8). The adc are moderately wide, of average height and of the ‘archiaci’ type. Equatorial chamberlets are moderately wide and high, with ‘archiaci’-type growth pattern. This species includes four subspecies: D. a. bakhchisaraiensis Less, 1987; Dmean < 305 μm; D. a. staroseliensis Less, 1987; Dmean = 305–390 μm; D. a. archiaci (Schlumberger, 1903); Dmean = 390–600 μm; and D. a. bartholomei (Schlumberger, 1903); Dmean > 600 μm (Less, 1998).

7

Discocyclina archiaci (Schlumberger, 1903) bakhchisaraiensis Less, 1987 Plate 1, Figures 1–4, Plate 2, Figures 3–5, Plate 3, Figures 1–3, Plate 6, Figures 3–5, 11; Figures 10–13 1987 D. archiaci (Schlumberger, 1903) bakhchisaraiensis n. ssp. Less, p. 130–131, pl. 1, figs. 1–6, text figs. 26a, b & 27a. 2003 D. archiaci (Schlumberger, 1903) bakhchisaraiensis Less, 1987. Çolakoğlu & Özcan, p. 5, pl. 2, fig. 10, text fig. 4. 2007 D. archiaci (Schlumberger, 1903) bakhchisaraiensis Less, 1987. Less et al., p. 433, pl. 1, figs. 19–20, fig. 13. 2013 D. archiaci (Schlumberger, 1903) bakhchisaraiensis Less, 1987. Özcan et al., pl. 1, figs. 1a, 1b, 2a, 2b. 2014 D. archiaci (Schlumberger, 1903) bakhchisaraiensis Less, 1987. Özcan, Scheibner, & Boukhalfa, p. 215–218, fig. 15.18–24, fig. 17. Remarks. D. a. bakhchisaraiensis is a key subspecies for OZ 3 in western Tethys, first appearing in the lower part of early Eocene but not immediately at or around the P/E boundary (Figure 9) (Less et al., 2007; Özcan, Scheibner, & Boukhalfa, 2014). D. archiaci is herein reported for the first time from Indo-Pakistan region. The differentiation of this species from closely associated D. ranikotensis based on the external test features is not straightforward. Both species are characterised by having flat tests with a central umbo and uniformly distributed pillars, which are characteristically coarser in the umbonal part (Plate 7, Figures 1 and 3). In general, the test of D. ranikotensis is larger than that of D. archiaci, while (?) juvenile specimens of the former species with small tests were also recorded in some levels of the Patala Formation. In equatorial sections, D. archiaci and D. ranikotensis is differentiated from each other on the basis of three parameters; (a) type of embryon configuration, (b) embryon size and (c) height of annular chambers, which are best observed and compared in sections exposing the test along the equatorial layer. Some specimens, however, may show intermediate features that make the differentiation difficult. These specimens are marked by a question mark in Figure 10. D. archiaci in Patala Formation has invariably semi-nephro to trybliolepidine-type embryons, while D. ranikotensis has commonly umbilicolepidine-type embryons (Figures 10–13). In western Tethys, D. archiaci has such umbilicolepidine embryons only in the late stage of its development, which is represented by D. archiaci bartholomei, (with Dmean > 600 μm) in upper Ypresian and early Lutetian (Özcan et al., 2007). The specimens of D. archiaci in Patala Formation have much smaller embryons than D. ranikotensis, a feature confirming Davies’s (1927) argument for the distinction of both species. D. archiaci in Patala Formation belongs to D. a. bakhchisaraiensis,


8

E. Özcan et al.

and also transitional stages of D. a. bakhchisaraiensis and D. a. staroseliensis based on the average size of the deuteroconch ranging between 256 and 318 μm (Table 1), suggesting that umbilicolepidine-type embryons should belong to another lineage but not to D. archiaci. The nummulitid and rotaliid foraminifera in the Patala Formation also support a stratigraphic position in early Eocene but not Thanetian, consistent with the evolutionary state of D. archiaci. If we consider the development of annular chambers, the annular chambers in the juvenile and adult stages of D. archiaci are characteristically lower than those of D. ranikotensis (Figure 13; Table 1). The heights of these chambers in both species vary between 20 to 50 μm and 40 to 90 μm, respectively. This is also reflected in parameter n .5, which is usually more than 10 in D. archiaci (Table 1). D. archiaci is very close to D. ranikotensis in vertical sections in terms of development of lateral chamberlets and pillars, although the embryons of the latter species are evidently higher and larger (Plate 6 Figures 1–5). The best criterion to differentiate both species in off-centred vertical sections is the number of annular chambers within a specific interval (parameter n .5) as the shapes of equatorial chambers as well as their thicknesses are very similar (compare the annular chambers in Plate 7, Figures 2, 4, 5). The lateral chamberlets in D. archiaci present a close similarity to that of D. ranikotensis; their heights are between 25 and 40 μm and width between 100 and 140 μm at the central part of the test. D. archiaci and Paleocene Setia and Orbitosiphon are differentiated from each other based on the three criteria; presence/absence of lateral chamberlets on both side of the equatorial layer, thickness of equatorial layer and size of lateral chamberlets. As previously illustrated and discussed by Ferrández-Cañadell (2002), the absence of lateral chamberlet on one side of the plano-convex test of Setia (Plate 6, Figures 6–8; Plate 7, Figure 6) permits the distinction of this taxon from Orbitosiphon (Plate 6, Figure 9) and orthophragminids. The height and width of lateral chamberlets in Setia and Orbitosiphon are much lower (around 20–25 μm) than D. archiaci and D. ranikotensis (around 30–40 μm). Discocyclina archiaci (Schlumberger, 1903) ex. interc. bakhchisaraiensis Less, 1987- staroseliensis Less, 1987 Figure 10 The lowest sample in THAL section represents an advanced stage of D. a. bakhchisaraiensis, accociated with D. ranikotensis. Discocyclina archiaci (Schlumberger, 1903) ex. interc. staroseliensis Less, 1987 bakhchisaraiensis Less, 1987 Plate 1, Figures 5–8; Plate 2, Figures 1, 2; Plate 3, Figure 4; Plate 6, Figure 10; Figures 10–12 D. archiaci assemblages in samples THAL. 8, 10, 11 and THAL.A belong to the primitive D. a. staroseliensis,

indicating a transitional developmental stage from ‘bakhchisaraiensis’ and ‘staroseliensis’. A microspheric specimen from sample THAL.10 show an initial stage with spiral chambers, followed by subdivided falciform chambers, and annular chambers, a development observed only in Discocyclinidae (e.g. genera Discocyclina and Nemkovella) (Plate 6, Figure 10). Discocyclina ranikotensis Davies, 1927 emend. Plate 4, Figures 1–5; Plate 5, Figures 1–5; Plate 6, Figures 1, 2; Plate 7, Figures 1, 2; Figures 10–13 1927 D. ranikotensis sp. nov. Davies, p. 281, pl. XXII, figs. 10–12, text fig. 4 (also illustrated in Figure 12 in present work) ? 1937 D. ranikotensis Davies, 1927. Davies & Pinfold, p. 55, pl. 5, fig. 22 non 1959 D. ranikotensis Davies, 1927. Nagappa, pl. 3, fig. 3, pl. 8, figs. 2–3 (= D. archiaci) non 1967 D. ranikotensis Davies, 1927. Köhler, p. 70, 71, pl. XIII, figs. 2–4 [=? advanced developmental stages of D. archiaci (fig. 3) and ? D. fortisi (fig. 4)] non 1976 D. ranikotensis Davies, 1927. Latif, pl. 15, fig. 7 (= Orbitosiphon punjabensis) non 1991 D. ranikotensis Davies, 1927. Butt, pl. 3, fig. g (= Setia indet. sp.) non 1993 D. ranikotensis Davies, 1927. Weiss, pl. 1, fig. 3, pl. 2, figs. 1–2, pl. 3, fig. 1, pl. 4, fig. 5, pl. 6, fig. 7 [= Setia tibetica (pl. 1, fig. 3); D. archiaci (pl. 6, fig. 7)] non 2000 D. ranikotensis Davies, 1927. Mirza, Sameeni, & Rashid, pl. 2, fig. 3 (= Orbitosiphon punjabensis and Setia indet. sp.) non 2002 D. ranikotensis Davies, 1927. Ferrández-Cañadell, pl. 2, figs. 8–9 (= Discocyclina indet. sp.) non 2005 D. ranikotensis Davies, 1927. Mirza et al., pl. 4, fig. 5 (= Discocyclina indet. sp.) non 2005 D. ranikotensis Davies, 1927. Afzal et al., pl. 3, fig. 12 (= Setia indet. sp.) non 2008 D. ranikotensis Davies, 1927. Babazadeh, fig. 4e (= Discocyclina indet. sp.) non 2011 D. ranikotensis Davies, 1927. Babazadeh, fig. 3.12, fig. 4.3, 7, 12 (= Discocyclina indet. sp.) non 2009 D. ranikotensis Davies, 1927. Sameeni et al., pl. 2, fig. g., pl. 3, fig. f [=? Orbitosiphon punjabensis (pl. 2, fig. g), Setia indet sp. (pl. 3, fig. f)] non 2010 D. ranikotensis Davies, 1927. Afzal et al., fig. 9ı (= Discocyclina indet. sp.) non 2013 D. ranikotensis Davies, 1927. Imraz, pl. 4.3, figs. e, f, pl. 4.4, fig. a, pl. 5.2, fig. b. [= Setia indet. sp. (pl. 4.3, fig. f, pl. 4.4, fig. a), Orbitosiphon punjabensis (pl. 5.2, fig. b, pl. 4.3, fig.e)] non 2013 D. ranikotensis Davies, 1927. Hanif, Ali, & Afridi, pl. 2, fig. h (= Setia indet. sp.) non 2014 D. ranikotensis Davies, 1927. Sameeni et al., pl. 4 (= Setia indet. sp.) Emended diagnosis. D. ranikotensis is an unribbed species having a flat test with central umbo and uniformly distributed pillars, coarser in umbonal part. The embryon

Geodinamica Acta


is large, trybliolepidine to umbilicolepidine-type, rarely the distal wall of protoconch touching the deuteroconchal wall. The adc are moderately wide and high, and of the ‘archiaci’ type. Equatorial chamberlets are wide and high, with ‘archiaci’-type growth pattern. Emended description. The test, usually between 3–7 mm in diameter but reaching up to 1 mm in microspheric forms, has a circular outline and lenticular shape, with a pronounced umbo at the centre. The granules, evenly distributed over the surface of the test, are more pronounced at the umbonal part and may reach up to 90 microns in diameter (Plate 7, Figures 1 and 2). The peripheral granules, much smaller in size, are hardly visible. In megalospheric forms, the protoconch is subspherical with an average diameter ranging from 200 to 290 μm (Table 1), followed by large and rather irregular deuteroconch with an average diameter ranging from 440 to 650 μm. The protoconch is enclosed by the deuteroconch by varying states of embracement, but mostly resulting in an umbilicolepidine-type configuration although the trybliolepidine-type is also observed (Figures 10–13). In some cases, the walls of both embryonic chambers may touch each other at some points as observed in the equatorial layer (Plate 4; Figures 3, 10–12), resulting in a multilepidine-type appearance of the embryon. The adauxiliary chambers are high and numerous and, in some case slightly arched at their distal sides and are followed by annular chambers with high and wide chamberlets, presenting archiaci-type growth pattern. The annular chambers at the adult stage are distinctly rectangular in shape. Remarks. The embryons of D. ranikotensis in Patala Formation are much larger than that of D. archiaci although the latter species has not been described from this unit in Thal (Table 1). The discocyclinids with such large embryons do not occur in western Tethys (Less, 1998; Less et al., 2007), leading to the rejection of D. ranikotensis by some LBF experts (Less, 1987; Neumann, 1958). Our data suggest that this is one of the chief criteria to differentiate closely associated D. archiaci and D. ranikotensis. This species has usually umbilicolepidine-type embryons, which are not observed in early Eocene D. archiaci, but only seen at its advanced developmental stages in late early Eocene and early Lutetian (Özcan et al., 2007). Some embryons of D. ranikotensis may sporadically possess trybliolepidinetype configuration (e.g. specimens THAL.B-42, 44; THAL.A-52, 13 and 6 in Figure 12) while, in others, the wall of protoconch may touch the wall of deuteroconch at some point giving a ‘three-locular’ appearance of embryon (multilepidine-type configuration of Less, 1987) (Plate 4, Figure 3). In this respect, they are very close to D. pseudoaugustae Portnaya, 1974, which is confined to OZ 4–5 in western Tethys. The specimens yielding such embryons could represent early stage of D. pseudoaugustae in OZ 3. The criteria for the differentiation of

9

D. ranikotensis from other associated orthophragminids are given above in remarks for D. archiaci. An evolution in this species based on the embryonic parameters, such as size of the deuteroconch, the most important evolutionary parameter in orthophragminids, is not recorded in the studied section (Figure 14). The associated specimens with multilepidine and centrilepidine-type embryons, characteristic for early Eocene D. pseudoaugustae and D. fortisi, respectively in western Tethys, suggests that D. fortisi may have descended from D. ranikotensis stock. The ancestor of D. ranikotensis is not known. In addition to our findings in present study, we have also identified D. ranikotensis in the upper part of the Patala Formation in Nammal Gorge Section in Salt Range (Figure 12: unpublished data of M. Hanif, N. Ali, & E. Özcan). In these beds, D. ranikotensis is associated with Alveolina vredenburgi, an index alveolinid for SBZ 5 (OZ 2). Thus, stratigraphic range of this species is proposed to cover OZ 2 and 3 (Figure 9). Discocyclina dispansa (Sowerby, 1840) Plate 7, Figure 7 1840 Lycophris dispansus n. sp. Sowerby, p. 327, pl. 24, figs. 16a, b. Diagnosis. Discocyclina dispansa is a small to large sized, flat to saddle shaped, unribbed form. The small to medium-sized megalospheric embryon is semi-nephrolepidine in the older members (e.g. D. d. broennimanni and D. d. taurica) and is trybliolepidine in the phylogenetically advanced members. The adc are moderately wide and high, and of the ‘archiaci’ type. The equatorial chamberlets are also moderately wide and high. This species includes six subspecies: D. d. broennimanni Less, 1987; Dmean < 160 μm; D. d. taurica Less, 1987; Dmean = 160–230 μm; D. d. hungarica Kecskeméti, 1959; Dmean = 230–290 μm; D. d. sella (d’Archiac, 1850); Dmean = 290–400 μm; D. d. dispansa (Sowerby, 1840); Dmean = 400–520 μm; and D. d. umbilicata (Deprat, 1905), Dmean > 520 μm (Less, 1998). Remarks. D. dispansa is very sporadic in Patala Formation, although this species was suggested to be the most common orthophragminid in early Eocene of Pakistan (Afzal et al., 2010). We here illustrate the equatorial section of this species for the first time. This species is differentiated from early Eocene discocyclinids by having a very small embryon (Table 1), mostly presenting semi-nephrolepidine-type configuration. Since it is very rare, the vertical section of this species cannot be illustrated here. The specimens from THAL.A represent a transitional stage between D. d. broennimanni and D. d. taurica. The specimen illustrated by Afzal et al. (2010) for this species (Figure 9(G)) from early Eocene Dungan Formation in Pakistan is, in fact, an orbitoclypeid species (? O. schopeni), while the vertical section of the specimen illustrated in Figure 9(F) does not provide any information for its designation to D. dispansa.


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Figure 2. Simplified geological map of Thal area in western Kohat Plateau, N Pakistan and locations of THAL Section and spot samples THAL.A & B (black and white stars, respectively). Geological map is simplified from Khan et al. (2003).

Figure 3. Synthetic sections showing the lithostratigraphic subdivision and stratigraphic development of Palaeogene sediments in Thal area according to Davies (1927) and Beck et al. (1995). The studied portion of Patala Formation is tentatively marked in Davies’s stratigraphic column. S- Serpentinite.


Geodinamica Acta

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Figure 4. Records of D. ranikotensis in eastern and western Tethys. 1- ‘Upper Ranikot Beds’, Thal, NW Pakistan, 2- Lockhart Limestone, Salt Range, N Pakistan, 3- Vicentin, N Italy, 4- Ranikot Formation, Zinda Pir, W Pakistan and Nammal Formation, Salt Range, N Pakistan, 5- West Carpathian, Slovakia, 6- ‘Fourth Laki Series’ Rajasthan, India, 7- Lockhart Limestone, Changlagali, Hazara, N Pakistan, 8- Lockhart and Margala Hill limestones, Kala Chitta, Range. N Pakistan, 9- Lockhart, Patala and Nammal formations, Salt Range, N Pakistan, 10- Patala Formation, Kohat Basin, NW Pakistan, 11- Patala Formation, Jabri area, Hazara, N Pakistan. 12- Kohat Formation, NW Pakistan, 13- Lockhart Limestone, Kotal Pass, Kohat Basin, NW Pakistan, 14- Lockhart Limestone, Jabri, Hazara, N Pakistan, 15- Lakadong Limestone Member, Meghalaya, NE India, 16- Shiekhan Formation, Tarkhobi section, Kohat Basin, NW Pakistan, 17- Lockhart and Dungan formations, Indus Basin, Pakistan, 18- Lockhart Limestone (Upper Indus Basin) and Dungan Formation (Lower Indus Basin), N and W Pakistan, 19- Hassanabad Mahrood and south Birjand sections, E Iran, 20- Lockhart Limestone, Nilawahan Gorge, Salt Range, N Pakistan, 21- Lockhart Limestone, Nammal Gorge and Dhok Kas Sections, Salt Range, N Pakistan, 22- Patala Formation, Kala Dilli Section, Kala Chitta Range, N Pakistan, 23- Lockhart Limestone, Nammal Gorge Section, Salt Range, N Pakistan, 24- Patala Formation, Makarwal, Surghar Range, N Pakistan. According to Afzal et al. (2010), D. ranikotensis is confined to SBZ 4 to 7. Records based on external features, equatorial and vertical sections of the (megalospheric) specimens are denoted by ‘ex’, ‘e’ and ‘v’, respectively. Illustrations of the equatorial layer in microspheric specimens are shown by ‘em’. L- Lutetian, S- Selandian.

Discocyclina aff. fortisi (Archiac, 1850) Plate 5, Figures 6–7; Figures 11–13 Some discocyclinid specimens in the upper part of the Patala Formation possess large embryons (Table 1) presenting centrilepidine-type embryon configuration. The development of the annular chambers and their dimensions are otherwise very similar to D. ranikotensis. In western Tethys, the discocyclinids having such large embryons with centrilepidine embryonic configuration first appear in the lower part of upper Ypresian (OZ 5/6 and SBZ 10; middle part of early Eocene) (Less, 1998; Özcan et al., 2007; Zakrevskaya, Beniamovsky, Less, & Báldi-Beke, 2011). Our specimens from Thal are very similar to the most primitive developmental stage of D. fortisi (D. f. fortisi) based on the embryon dimensions while they are from different stratigraphic levels. Presently, based on the available data, we think that our specimens from Thal may belong to a different lineage although they may be linked to the primitive D. fortisi in western Tethys. We need material from the transitional beds from early to late Ypresian to observe the evolution of Thal specimens and their possible connection with D. fortisi.

Family Orbitoclypeidae Brönnimann, 1946 Genus Orbitoclypeus Silvestri, 1907 Type species: Orbitoclypeus varians (Kaufmann, 1867) Orbitoclypeus schopeni (Checchia-Rispoli, 1908) Plate 3, Figures 5–7 Orbitoides (Exagonocyclina) schopeni Checchia-Rispoli, 1908, p. 12. Diagnosis. O. schopeni is an unribbed species having a ‘marthae’-type rosette, a small to relatively large eulepidine, trybliolepidine or excentrilepidine embryon, narrow or medium-wide, low or medium-high ‘varians’-type adc and also narrow or medium-wide equatorial chamberlets arranged into circular or slightly undulated annuli with usually ‘varians’-type growth pattern. The distal margins of the annular chamberlets are typically arched or wedge-shaped. This species includes five subspecies: O. s. ramaraoi (Samanta, 1967); Dmean < 195 μm; O. s. neumannae (Toumarkine, 1967); Dmean = 195–240 μm; O. s. suvlukayensis Less, 1987; Dmean = 240–300 μm; O. s. crimensis Less,


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Figure 5. Field aspects and distribution of samples in the THAL Section along the eastern bank of Ishkalai River, Thal. Kadimak Mountain is at the background.

Figure 6. Lithostratigraphic column of Patala Formation in THAL Section and distribution of LBF with inferred orthophragminid and larger benthic foraminiferal zones. SBZ- shallow benthic zones by Serra-Kiel et al. (1998). OZ- orthophragminid zones by Less (1998), Less et al. (2007) and updated by Özcan et al. (2010).


Geodinamica Acta 1987; Dmean = 300–500 μm; and O. s. schopeni (Checchia-Rispoli, 1908); Dmean > 500 μm (Less, 1998). Remarks. O. schopeni is very sporadic in Patala Formation, most probably because of very shallow depositional characteristics of the unit. In Patala Formation, this species is differentiated from the associated discocyclinids by having a typical eulepidine-type small embryon (Plate 3, Figure 6) (Table 1). Some specimens of O. schopeni from early Eocene of Turkey are illustrated in Plate 3, Figures 5 and 7 for comparison. The specimen from Thal with a deuteroconch diameter of 200 μm falls within the biometric limits of O. s. neumannae. Until now, this species has not been illustrated from Pakistan while its very primitive developmental stage, O. ramaraoi, has originally been described from eastern India (Samanta, 1967). The specimens illustrated by Afzal et al. (2010; Figure 9k) as Orbitoclypeus sp. belongs to O. schopeni. Ferrández-Cañadell (2002) reported the occurrence of O. schopeni (O. ramaraoi) in early Eocene part of the Patala Formation in Salt Range without any illustration. 7. Evaluation of orthophragminid record in Patala Formation and assignment of OZ zones The Paleocene–early Eocene sedimentary sequence unconformably overlying the Cretaceous units in Thal area is represented by thick, ca. 400-m-thick succession of fine-grained clastic rocks, from which Davies (1927) reported the occurrence of rich LBF only at its upper part (upper most part of ‘upper Ranikot beds’; Zone 4 of Davies). Our data show that Zone 4 of Davies is, in fact, thicker than what has been reported. The LBF foraminifera occurring in the studied section and the spot samples, represented by nummulitids, rotalids, alveolinids and orthophragminids, are all symbiotic and thus, their associations suggest a shallow water habitat, indicative of water depths within the photic zone (Hottinger, 1983, 1997). Hottinger (1997) suggested that orthophragminids are restricted to the deeper part of upper photic zone (water depth ca. 40–80 m) and to lower photic zone (water depth ca. 80–120 m) in neritic environments, while alveolinids, Nummulites sp., Ranikothalia sp., Lockhartia sp. are confined to upper photic zone. However, there are such records indicating LBF assemblages, such as Assilina and Discocyclina, both from protected marine environments with a water depth of ca 30 m as well as from more open parts of platform with a depth of 50–80 m, suggesting that associations of LBF from the rock record can only be used as relative bathymetric indicators (Beavington-Penney & Racey, 2004). Sinclair, Sayer, & Tucker (1998) have shown that orthophragminids (discocyclinids) occur at extreme depositional environments in carbonate ramp profile, both in sheltered back-shoal facies in inner ramp (water depth ca. 5–20 m) and dominantly in outer ramp setting (water depth ca. 35–130 m) in their LBF distribution model from French Alps. The LBF in THAL Section and spot samples, comprising Ranikothalia nuttalli, R. sindensis, R. thalicus,

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Miscellanea sp. Daviesina sp., Lockhartia haimei, L. conditi, Rotalia newboldi, Nummulites sp., Assilina sp. and Alveolina sp. suggest a shallow-marine depositional setting, most probably in inner-shelf setting for the Patala Formation. This interpretation follows the distribution model of larger foraminifera in fossil record from ancient ramps and shelves (Buxton & Pedley, 1989; Hottinger, 1997; Sinclair et al., 1998; Beavington-Penney & Racey, 2004). This is also supported by the common occurrence of discocyclinids and lack of orbitoclypeids and asterocyclinids in Patala Formation in Thal, which is in accordance with our previous observations on the distribution of orthophragminids from the western Tethyan platforms where discocyclinids chiefly occur in nummulitid-alveolinid facies and orbitoclypeids and asterocyclinids in comparatively deeper marine marls deposited in outer shelf (Özcan et al., 2007; Ben İsmail-Lattrache et al., 2013). The lack of ribbed orbitoclypeids (e.g. Orbitoclypeus munieri and O. bayani) and asterocyclinids (e.g. Asterocyclina taramellii) and nemkovellids (Nemkovella evae and N. stockari) in the studied part of the Patala Formation may not be significant for the diversity interpretation. The absence of these taxa in studied section may be due to the lack of favourite habitat for asterocyclinids and orbitoclypeids. On the other hand, our recent records from shallow marine units in India suggest that orthophragminids are less diversified in this part of the Tethys. The late Middle Eocene shallow-marine beds of Fulra Limestone from Kutch, W India indicate that orthophragminids are represented by less number of species than those of western Tethys (Ben İsmail-Lattrache et al., 2014; Özcan & Saraswati, 2014). In addition, our unpublished studies on LBF-bearing carbonate/clastic levels interbedded with planktonic foraminiferal marls in the upper part of the Patala Formation in Salt Range and early Eocene shallow-water carbonates in northern Oman show that orthophragminids are represented by only few species. Patala Formation in Salt Range contains D. ranikotensis, D. dispansa and O. schopeni (unpublished data of M. Hanif, N. Ali and E. Özcan), while the inner platform carbonates of the Jafnany Formation in Oman contains only Nemkovella stockari (unpublished data of E. Özcan and I. Abbasi). The planktonic foraminiferal marly sequence of Patala Formation in Salt Range containing allochthonous LBF such as alveolinids and nummulitids (Hottinger et al., 1998), penecontemporaneous with the sedimentation at its upper part is thought to have deposited in an outer shelf setting, an environment deeper than that of Patala beds in Thal and more favourable for orthophragminids. It is very probable that early Eocene orthophragminids in Indo-Pakistan region, and thus in NW Himalayas, are less diverse than western Tethyan assemblages in this time slice. To confirm this, further studies are required in sediments deposited in transitional platform to basin setting in Pakistan and NW Himalayas. Based on the dominant occurrence of primitive D. archiaci (D. a. bakhchisaraiensis) throughout its

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Figure 7. Morphologic and morphostructural features of D. ranikotensis and D. archiaci and illustrations of the parameters used in the description of orthophragminids; scale bars = 600 μm for (a) and (b), and 200 μm for the others. (a, b) vertical sections of D. ranikotensis and D. archiaci from Patala Formation (Thal, Pakistan) illustrating the bi-locular embryonic apparatus. ea: embryonic apparatus, el: equatorial layer, lc: lateral chambers, p: pillars (piles). (c–e) Equatorial sections of D. archiaci from Patala Formation (Thal, Pakistan) (c) and Karakaya Formation (central Turkey) (d, e) showing the embryonic chambers, peri-embryonic chambers/ chamberlets and the biometric parameters P, D, A, H, W, n .5, h, and w used in the description of megalospheric orthophragmines; P and D- outer diameter of protoconch and deuteroconch perpendicular to their common axis; A- number of adauxiliary chamberlets; H and W- height and width of the adauxiliary chamberlets; h and w- height and width of equatorial chamberlets around the peripheral part of the equatorial layer; n .5 – number of annuli within .5 mm distance measured from the deuteroconch along the axis of the embryon. P- protoconch, D- deuteroconch, ps- protoconchal stolon, des- deuteroconchal embryonic stolons, pac- principal auxiliary chamberlets, adc- adauxiliary chamberlets, ch- chamberlets, s- septum, se- septulum, rs- radial stolon, as- annular stolon; the circle indicates the annular stolons at proximal and almost central part of the septulum. (f, g) Comparison of nepionic stages of two different microspheric orthophragminid juvenaria; f- early spiral chambers followed by orbitoidal isolated chamberlets, which become annular in the later stage of development after the introduction of progressive chamber (pc), and are characteristic of the Orbitoclypeidae, g- early spiral part followed by subdivided falciform chambers and first annular chamber (ac), characteristic of the Discocyclinidae; (f) is Asterocyclina stellata from Bartonian Soğucak Formation (Thrace Basin, Turkey) and (g) is D. archiaci from Patala Formation (Thal, Pakistan).


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Figure 8. Qualitative features of Tethyan orthophragminids. (a) types of embryon configurations (suffix ‘-lepidine’ is to be added); (b) types of the adauxiliary chamberlets; (c) different growth patterns of the equatorial annuli; d- types of the rosette (the network of granules and lateral chamberlets on the test surface). From Less (1987).

development and occurrence of D. ranikotensis in association with A. vredenburgi in Lower Eocene sediments (SBZ 5) of Patala Formation in Salt Range, we assign OZ 2?–3 to the studied portion of the Patala Formation in Thal (Figure 9). This is in accordance with the previously proposed ages of this unit in Thal based on the planktonic foraminifera suggesting P6 for the upper part of marine sequence below Kohat Formation (Beck et al., 1995). This age designation also conforms to that of Afzal et al. (2009), suggesting SBZ 4–9 zones for the Patala Formation in Upper Indus Basin. The Patala Formation in many earlier works, however, has been interpreted predominantly as an upper Paleocene unit in Salt Range, while its upper part is recognised to cross the Paleocene/Eocene boundary (Köthe et al., 1988). The difference in age designations are, however, partly results from the position of the Paleocene-Eocene boundary itself, since taxa would be restricted to upper Paleocene using one scheme (Haynes et al., 2010; Serra-Kiel et al., 1998), yet range into the early Eocene using the another scheme (Hottinger, 2014; Pujalte, Baceta, et al., 2009; Pujalte, Schmitz, et al., 2009).

Recently, Hottinger (2009) placed the uppermost part of the Patala Formation in Salt Range within SBZ 5 (Hottinger, 2009) based on the record of miscellanids and also supposed occurrence of A. vredenburgi, a key alveolinid species for SBZ 5 (Hottinger, Sameeni, & Butt, 1998). The assignment of OZ 2 ?- 3 to the THAL Section, however, leads to a contradiction with the presently accepted stratigraphic ranges of some nummulitid taxa, particularly with the miscellanids in Patala Formation. According to Hottinger (2009), miscellanids became extinct in Tethys at SBZ 5/6 boundary, which is placed within the OZ 2 during earliest Eocene. In THAL Section, miscellanids occur throughout the Section associating with D. a. bakhchisaraiensis and D. ranikotensis (Figure 6). We do not favour any reworking of miscellanids from the older strata as they occur consistently almost in all studied samples. The co-occurrence of miscellanids with the early developmental stage of primitive D. archiaci has never been recorded in peri-Mediterranean region. This arise the possibility that the stratigraphic range of miscellanids may, in fact, extend into the younger


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Figure 9. Distribution of orthophragminids in late Paleocene- early Eocene time slice and correlation of orthophragminid zones (OZ) to shallow benthic zones (SBZ) in Tethys (after Less, 1998; Less et al., 2007; Özcan et al., 2001; Serra-Kiel et al., 1998). First appearance of ribbed orbitoclypeid and asterocyclinid species across the P/E boundary in western Tethyan platforms are marked by open circles, and nemkovellids by black circles, respectively. The stratigraphic range of D. ranikotensis is provisional in the light of the available data only from Patala Formation in Thal area and Salt Range in Pakistan. The correlation of OZ zones to SBZ zones and the time scale are after Özcan et al. (2010). Planktonic foraminiferal zones (P) are from Berggren et al. (1995). Calcareous nannoplankton zones (NP) are based on Martini (1971), and their correlation to the time scale is from Berggren et al. (1995). L- Lutetian.

stratigraphic levels, such as SBZ 6 and 7, as opposed to previously accepted ranges of this group. The younger part of the miscellanid stratigraphy of Hottinger (2009) in earliest Eocene has been chiefly established from the Patala Formation in Salt Range where this unit has a limited thickness and miscellanid record ends dramatically at its upper part because of a facies change taking place in transition to overlying Nammal Formation. Thus, the absence of miscellanids in Nammal Formation in Nammal Gorge and Dhak Pass sections in Salt Range could be related with environmental factors rather than their extinction. The abrupt facies change as evidenced by the development of continental deposits with coal seams and open marine beds in the upper part of the Patala Formation in the Salt Range also favours facies control on the LBF record (Afzal et al., 2009; Kazmi & Abbasi, 2008). As an alternative to this, we may also speculate that OZ 2–3 boundary can be lowered such that lower part of OZ 3 can be correlated partly with SBZ 5/6 by assuming that first appearance datum of this species is earlier in eastern Tethys. However, at present, in the absence of independent dating tools that would provide a high-resolution stratigraphy, this proposal cannot be tested and requires further studies in shallow-marine

sections containing more diverse and index-taxa for an integrated biostratigraphy. 8. Palaeobiogeographic synthesis The correlation of western Tethyan orthophragminids to those in the coeval deposits in Indo-Pakistan region (NW Himalayas) and Himalayas is hampered by a lack of taxomic studies in these regions, posing a handicap for the creation of a thorough synthesis of orthophragminid palaeogeography for Tethys and worldwide (Ben İsmail-Lattrache et al., 2014; Less, 1987; Özcan et al., 2014). Nevertheless, our present study provides the first concrete data to overview the early Eocene orthophragminid distribution in Tethys. Our data suggest that early Eocene orthophragminids in NW Pakistan consist of taxa with western Tethyan affinities, such as D. archiaci, D. dispansa and O. schopeni, while latter two are very sparse in THAL Section. Among these, D. archiaci is very common in western Tethyan lower Eocene sediments, and is a key species for OZ zones (Less et al., 2007; Özcan et al., 2007) while D. dispansa is sparse similarly to its occurrence in Thal. O. schopeni, that inhabits an outer shelf environment, have less environmental tolerance to shallow-marine inner-shelf

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Figure 10. Embryon and its variation in D. archiaci bakhchisaraiensis, D. archiaci ex. interc. bakhchisaraiensis-staroseliensis, D. archiaci ex. interc. staroseliensis-bakhchisaraiensis, and D. ranikotensis from the samples THAL.1, 2, 3, 8 & 10. The labels denote specimen numbers in the sample. Question mark is for the hesitation in species assignment of some specimens.

setting and commonly occurs in sediments with a depositional setting transitional between shelf to basin (Ben İsmail-Lattrache et al., 2014). Considering our findings in present study and also the occurrence of D. archiaci

in early Eocene sediments in Ivory Coast (unpublished data of D. Z. Bruno, Ben I. Lattrache & E. Özcan), associating with early developmental stages of D. fortisi, we suggest a widespread dispersal and adaptation of this

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Figure 11. Embryon features and variation in D. archiaci bakhchisaraiensis, D. archiaci ex. interc. staroseliensis-bakhchisaraiensis, and D. ranikotensis from the samples THAL.11, 12, 14, 16. The specimen THAL.16–44 shows twin development of megalospheric embryon. The labels denote specimen numbers in the sample.

species in Tethys. The only record of this species in Cauvery Basin in SE India by Govindan (2013) has to be re-evaluated since this species has not yet been

illustrated. Moreover, Govindan (2013) considered that D. ranikotensis might be the senior synonym of D. archiaci that would lead to disregard the possible

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Geodinamica Acta

Figure 12. Embryon features and variation in D. archiaci bakhchisaraiensis, D. archiaci ex. interc. staroseliensis-bakhchisaraiensis, D. ranikotensis and D. aff. fortisi from the samples THAL.A, B and samples 396 and ERE.24 from early Eocene of Turkey. Davies’s (1927) only illustration of D. ranikotensis embryon from Thal is redrawn and shown here. D. ranikotensis from the upper part of Patala Formation in Nammal Gorge Section (Salt Range) is illustrated. The labels denote specimen numbers in the sample. NAM = Sample Nammal Gorge (unpublished data of M. Hanif, N. Ali, & E. Özcan).

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Figure 13.

Comparison of embryon and development of annular chambers in D. archiaci, D. ranikotensis and D. aff. fortisi.

occurrence of D. ranikotensis in India. The updated palaeogeographic distribution of D. archiaci is shown in Figure 15. In addition to our findings in the present

study, we have also identified D. ranikotensis in the upper part of the Patala Formation in Nammal Gorge Section in Salt Range (unpublished data of M. Hanif, N.


Geodinamica Acta

Figure 14. Distribution of mean P (protoconch) and D (deuteroconch) values of D. archiaci and D. ranikotensis populations from Patala Formation in Thal area. The numbers denote sample numbers.

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Ali, & E. Özcan). Our data combined with previous poor information suggest that D. ranikotensis is endemic at least to Indo-Pakistan region while the composition of orthophragminids in Tibet is not known (Zhang et al., 2013). One of the most common orthophragminid taxa in western Tethys, Indo-Pakistan region and in SE and S Asia during Eocene is D. dispansa, which is the geographically most widespread discocyclinid during late middle Eocene (Ben İsmail-Lattrache et al., 2014; Huang et al., 2013; Özcan & Saraswati, 2014; Samanta & Lahiri, 1985). In THAL Section, D. dispansa is very rare. The few previous records of this species from Pakistan cannot safely be used for its geographic distribution during early Eocene because the species designations cannot be justified in vertical sections (e.g. D. dispansa in Afzal et al., 2010). O. schopeni, common to eastern and western Tethyan domains during early Eocene (Ferrández-Cañadell, 2002; Samanta, 1967), is the only orbitoclypeid known in eastern Tethys (Figure 15). Until now, the orbitoclypeids with ribbed tests (e.g. O. bayani and O. munieri in early Eocene) have not been recorded in eastern Tethyan deposits. In general, orthophragminid taxa with ribs (including Asterocyclina) are either lacking

Figure 15. The palaeogeographic distribution of D. archiaci, D. ranikotensis, D. dispansa and O. schopeni in early Eocene (except the records of O. schopeni and D. ranikotensis in locality 11, and O. schopeni in locality 12 & 13, which are from late Paleocene). Paleocoastline map at 53 Ma are redrawn from Smith, Smith, & Funnell (1994). (1) Aquitaine Basin (France): d’Archiac, 1850; Schlumberger, 1903; Douvillé, 1922; Schweighauser, 1953; Neumann, 1958; Less, 1987. (2) Spilecco (northern Italy): Schweighauser, 1953; Less, 1987 & 1998. (3) Gmunden (Austria): Dulai et al., 2010. (4) Dikilitash, Varna (Bulgaria): Less, 1998; Less et al., 2007. (5) central and eastern Crimea (Ukrania): Portnaya, 1974; Less, 1987; Zakrevskaya, 2005; Zakrevskaya et al., 2011. (6) Kocaeli peninsula, Thrace Basin and Şile (western Turkey): Özcan et al., 2010, 2012; Less et al., 2007. (7) Safranbolu- Safranbolu Basin, Sakarya-Haymana Basin and Karakaya-Sarıyaka (central Turkey): Çolakoğlu & Özcan, 2003; Özcan, Less, & Kertész, 2007; Gül et al., 2012; Özcan et al., 2013. (8) Kesra Plateau (Tunisia): unpublished data of K. Boukhalfa, E. Özcan & Ben. I. Lattrache. (9) Galala (Egypt): Özcan, Scheibner & Boukhalfa, 2014. (10) Fresco area (SW Ivory Coast): unpublished data of D. Z. Bruno, Ben I. Lattrache & E. Özcan. (11) N Oman: Racey, 1995; Haynes, Racey, & Whittaker, 2010 (question mark indicates that both O. cf. schopeni and D. cf. ranikotensis have been reported but not figured). (12) Cauvery Basin (SE India): Samanta, 1967; Govindan, 2013 (question mark indicates that D. archiaci has been reported but not figured). (13) South Shillong (NE India): Jauhri, 1998 (question mark indicates that O. schopeni has been reported but not figured). (14) Salt Range (Pakistan): unpublished data of M. Hanif, N. Ali, & E. Özcan.

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Plate 1. Equatorial sections of D. archiaci from early Eocene Patala Formation, Thal, NW Pakistan. 1–4: D. archiaci (Schlumberger) bakhchisaraiensis Less. 1: THAL.B-121, 2: THAL.3–15, 3: THAL.3–19, 4: THAL.3–20. 5–6, 8: D. archiaci (Schlumberger) ex. interc. staroseliensis-bakhchisaraiensis Less. 5: THAL.8–19, 6: THAL.8–11, 8: THAL.11–1. 7: D. archiaci (Schlumberger) ex. interc. bakhchisaraiensis-staroseliensis Less., THAL.10–15, The specimen label denotes sample number, and specimen number (e.g. THAL.11–1).

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Plate 2. Equatorial sections of D. archiaci from early Eocene Patala Formation, Thal, NW Pakistan. 1–2: D. archiaci (Schlumberger) ex. interc. staroseliensis-bakhchisaraiensis Less. 1: THAL.11–29, 2: THAL.11–31. 3–5: D. archiaci (Schlumberger) bakhchisaraiensis Less. 3: THAL.12–43, 4: THAL.16–15, 5: THAL.16–42. The specimen label denotes sample number, and specimen number (e.g. THAL.11–31).

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Plate 3. Equatorial sections of D. archiaci and Orbitoclypeus schopeni from northern Tethyan platforms, Turkey (1–5, 7) and NW Pakistan (6). 1–3: D. archiaci (Schlumberger) bakhchisaraiensis Less. early Ypresian Sarıyaka section, Kırıkkale (C Turkey). 1: 396– 12, 2: 396–4, 3: 396–7. 4: D. archiaci (Schlumberger) ex. interc. staroseliensis-bakhchisaraiensis Less. early Ypresian Çaycuma Formation, Karamürsel, Kocaeli (NW Turkey), ERE.24–29. 5, 7: O. schopeni (Checchia-Rispoli) neumannae (Toumarkine), early Ypresian Çaycuma Formation, Karamürsel, Kocaeli (NW Turkey). 5: ERE.24–26, 7: ERE.24–44. 6: O. schopeni (Checchia-Rispoli). note the eulepidine-type embryon configuration, early Eocene Patala Formation, Thal, NW Pakistan, THAL.A-42. The specimen label denotes sample number, and specimen number (e.g. THAL.A-42).

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Geodinamica Acta

Plate 4. Equatorial sections of D. ranikotensis Davies from early Eocene Patala Formation, Thal, NW Pakistan. 1: THAL.B-44, 2: THAL.3–26, 3: THAL.3–29, 4: THAL.12–68, 5: THAL.12–71. The specimen label denotes sample number, and specimen number (e.g. THAL.B-44).

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Plate 5. Equatorial sections of D. ranikotensis and D. aff. fortisi from early Eocene Patala Formation, Thal, NW Pakistan. 1–5: D. ranikotensis Davies. 1: THAL.B-122, 2: THAL.B-28, 3: THAL.16–19, 4: THAL.3–27, 5: THAL.1–30. 6–7: D. aff. fortisi (d’Archiac). 6: THAL.B-24, 7: THAL.B-25. The specimen label denotes sample number, and specimen number (e.g. THAL.B-25).

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Plate 6. Vertical sections of D. ranikotensis, D. archiaci, Setia tibetica and Orbitosiphon punjabensis (1–9) and equatorial sections of D. archiaci (10–11). 1–2: D. ranikotensis Davies. megalospheric specimens, early Eocene Patala Formation, Thal, NW Pakistan. 1: THAL.B-132, 2: THAL.B-128. 3–5: D. archiaci (Schlumberger) bakhchisaraiensis Less. megalospheric (3 & 4) and microspheric (5) specimens, early Eocene Patala Formation, Thal, NW Pakistan. 3: THAL.B-130, 4: THAL.B-131, 5: THAL.B-68. 6–8: S. tibetica (Douvillé). vertical sections showing well-developed lateral chamberlets on the dorsal and vacuolar cavities on the ventral side of the almost concave-convex test. 6, 8 microspheric, 7 megalospheric specimen, late Paleocene (SBZ 4) Lockhart Limestone in Nammal Gorge, Salt Range, N Pakistan. Note thick equatorial layer, low dorsal lateral chamberlets and asymmetric test. 6: NAM.6–5, 7: NAM.6–4, 8: NAM.6–9. 9: O. punjabensis (Davies), microspheric specimen showing development of lateral chamberlets on both sides of the thick equatorial layer, late Paleocene (SBZ 4) Lockhart Limestone in Nammal Gorge, Salt Range, N Pakistan, NAM. 6–14. 10: D. archiaci (Schlumberger) ex. interc. staroseliensis-bakhchisaraiensis Less. early Eocene Patala Formation, Thal, NW Pakistan, microspheric specimen showing typical discocyclinid juvenarium, THAL.10–3. 11: D. archiaci (Schlumberger) bakhchisaraiensis Less. early Eocene Sarıyaka section, Kırıkkale (C Turkey), microspheric specimen showing typical discocyclinid juvenarium, 396–15. The specimen label denotes sample number, and specimen number (e.g. 396–15).

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Plate 7. External views of D. ranikotensis and D. archiaci (1, 3), vertical sections of D. archiaci, D. ranikotensis and S. tibetica (2, 4–6), and equatorial section of D. dispansa (7). 1–2: D. ranikotensis Davies. megalospheric specimen showing the evenly distributed pillars, coarser in the umbonal part (1) and vertical section showing the development of lateral chamberlets and high equatorial chambers (2), early Eocene Patala Formation, Thal, NW Pakistan, 1: THAL.B-124, see Figure 12 for the embryonic features of the same specimen. 2: THAL.B-132, same specimen with Plate 6, Figure 1. 3–5: D. archiaci (Schlumberger) bakhchisaraiensis Less. megalospheric form showing the external test features (3), vertical sections illustrating the development of lateral chamberlets and low equatorial chambers (4–5), 3 & 4 from early Eocene Patala Formation, Thal, NW Pakistan, 5 is from early Eocene of Sarıyaka, Kırıkkale, C Turkey. 3: THAL.B-126, 4: THAL.B-130, same specimen as in Plate 6, Figures 3, 5: 396–20. 6: S. tibetica (Douvillé). vertical section of microspheric form showing well-developed lateral chamberlets on the dorsal side of the almost concave-convex test., late Paleocene Lockhart Limestone (SBZ 4) in Nammal Gorge, Salt Range, N Pakistan, NAM.6–9. 7: D. dispansa (Soweby) ex. interc. taurica-broennimanni Less. equatorial section showing semi-nephrolepidine- type small embryon. early Eocene Patala Formation, Thal, NW Pakistan, THAL.A-43.

Geodinamica Acta or very rare in Eocene beds in Indo-Pakistan region (Özcan & Saraswati, 2014). The less diverse feature of orthophragminids from Indian subcontinent compared to peri-Mediterranean region (north Africa, Europe, Turkey) has been proposed for late Middle Eocene (Bartonian) by Ben İsmail-Lattrache et al. (2014), suggesting a decline in diversity towards eastern Tethys and W Pacific. Our present results for early Eocene are consistent with this trend while the geographic coverage of the detailed studies from Indo-Pakistan region and west Pacific region is very poor for a detailed palaeogeographic synthesis.


9. Conclusions (1) Early Eocene marly sequence of Patala Formation in NW Himalayas (Thal, N Pakistan) comprises a diverse LBF assemblage represented by nummulitids, orthophragminids, rotaliids, miscellanids and alveolinids, once considered to be representative foraminiferal assemblage for Thanetian. Orthophragminids, previously assumed to be represented by monospecific assemblages of D. ranikotensis at its type locality (Davies, 1927), in fact, comprise five species; D. ranikotensis, D. archiaci, D. dispansa, D. aff. fortisi and O. schopeni. (2) We concluded that D. ranikotensis is an early Eocene species, and seems to be geographically confined to Indo-Pakistan region, while the composition of early Eocene orthophragminids further east (central Himalayas) and west (Iran) of this region are not yet known. The records of this species in Thanetian (in Lockhart Limestone in Pakistan) cannot be supported since these records are mostly based on vertical sections of late Paleocene orbitoidiform larger foraminifera such as Setia and Orbitosiphon. An evolution in this species based on the embryonic parameters, such as size of the deuteroconch, the most important evolutionary parameter in orthophragminids, is not recorded in the studied section. However, some specimens exhibit multilepidine-type (‘trilocular-appearing’) embryons throughout the section, and centrilepidine-type embryons only at the upper part of Patala Formation. These specimens with multilepidine and centrilepidine-type embryons, characteristic for early Eocene D. pseudoaugustae and D. fortisi, respectively, in western Tethys, suggests that D. fortisi may have descended from D. ranikotensis stock. The ancestor of D. ranikotensis is not known. (3) We show that D. archiaci, a key taxon for early Eocene orthophragminid zonation in western Tethys, also occurs abundantly in NW Himalayas. This extends the geographic distribution of this species from Aquitaine Basin (France) in W Europe to NW Himalayas in Pakistan. Through-

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out the studied section, D. archiaci belongs to most primitive developmental stage in western Tethys, represented by D. archiaci bakhchisaraiensis, and transitional developmental stage between D. a. bakhchisaraiensis and D. a staroseliensis. The earliest records of D. archiaci and D. dispansa from western Tethys is known from OZ 3 (SBZ 7/8) in early Eocene. Considering the presence of D. ranikotensis also in earliest Eocene sediments (SBZ 5) of the Patala Formation in Salt Range, stratigraphic range of D. ranikotensis is provisionally proposed to cover OZ 2 and 3 zones. (4) The rare occurrence of orbitoclypeids (O. schopeni) and lack of asterocyclinids in Thal may be due to unfavourable environmental conditions for these taxa, mostly confined to outer shelf setting in western Tethyan neritic environments. Meantime, our recent studies from the almost coeval outer shelf sediments of Patala Formation in Salt Range (Pakistan) and inner ramp carbonates from northern Oman suggest than in these localities, early Eocene orthophragminids are not diverse and are represented only by a few species. A better understanding of orthophragminid diversity in eastern Tethys requires further studies of LBF assemblages in shallow marine sediments deposited in shelf/slope transition.

Acknowledgements We thank Gyorgy Less (Miskolc) and Vlasta Ćosović (Zagreb) for their constructive reviews of the manuscript. We are grateful to National centre of Excellence in Geology, University of Peshawar for providing travel support for field works in Pakistan. Prof. Dr Tahir Shah (Director), Dr Irfan Ullah Jan and Dr Muhammad Shafique were very kind in sharing their knowledge and assistance in regional geology and logistic. We also thank Mr Farhat Ullah, Mr Taj Mohammad, Mr Irfanullah and Mr Azmat Ullah Orakzai (Department of Geology, University of Peshawar) for their assistance in the fieldwork. Prof. Pratul Saraswati (Mumbai, India), Prof. Malcom Hart (Plymouth, UK) and Prof. Johannes Pignatti (Rome, Italy) provided some literature.

Disclosure statement No potential conflict of interest was reported by the authors.

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