Foraminiferal biostratigraphy, facies and sequence stratigraphy analysis across the K-Pg Boundary in Hazara, Lesser Himalayas (Dhudial Section)

ABSTRACT The sedimentary strata were sampled in the lesser Himalayas to probe paleoenvironmental changes across the Cretaceous-Paleogene (K-Pg) boundary in the eastern Tethys. The study provides an integrated lithologic and bio-sequence stratigraphic analysis, leading to paleoecology and paleoenvironmental interpretations. The planktic foraminiferal limestone of the late Cretaceous is overlain by lateritic sandstones and sandy foraminiferal limestones, the latter being of Paleocene age. Though the deposition of cretaceous strata mainly occurred in transgressive and high stand system tracts, the top of cretaceous is marked by type-I sequence boundary and low stand system tract, corresponding to the Paleocene Hangu Formation. Deposits below the K-Pg boundary zone interval have been correlated to the late Cenomanian Rotalipora reichel biozone to early Campanian Globotruncana ventricosa zone, with absence of Maastrichtian fauna. A marked change in fauna above the K-Pg boundary zone interval has been observed and manifested by presence of larger benthic foraminifera such as Lockhartia Davies, 1932 and Globanomalina Haque, 1956 genera. The boundary occurs at the contrasting inter-facial contact of the two rock units and advocates an early lowered sea-levels or dead ocean model. An organic bed of late Turonian-early Coniacian corresponds to the probable presence of the OAE3 and could represent a missing link in the late Cretaceous of lesser Himalayas in the Pakistani domain. Prior to the K-Pg event and Indo-Eurasian collision, an influx of siliciclastics suggests a major episode of uplift and shortening caused by ophiolite obduction or magmatic upwelling during the Campanian. The subsequent erosion and its re-deposition shaped the platform, evolving it from relatively steeper ramp geometry in the Campanian to gentler epeiric ramp in the Selandian and Thanetian, and triggered deposition of shallow ramp larger benthic foraminiferal facies. The boundary is similar in nature with erosional phase in the whole region but its duration was prolonged in the study section and its upper limit has some regional changes. As finding of this study, the late Cretaceous “Nara Sandstone Member” of the Kawagarh Formation in Hazara area of earlier workers could be revised as Paleocene Hangu Formation.


INTRODUCTION
The Cretaceous-Paleogene (K-Pg) boundary is widely studied to know the causes of the extinction event that occurred during the time period and its effect on the flora and fauna. At its extreme, the end Cretaceous mass extinction vanished about 75% of marine and almost 50% of land species (Ryder et al. 1996;Hallam & Wignall 1997;Alroy 2008). However, the event was biologically selective as the extinction had greater intensity in the Northern Hemisphere (Keller et al. 1993;Nichols & Johnson 2002;Jiang et al. 2010;Donovan et al. 2016). The extinction event records paleooceanographic, paleobiological and climatic changes evolving from much warmer to cool greenhouse and are responsible for wiping out the planktonic foraminifera in majority of sections around the world (Molina et al. 1996;Hay & Floegel 2012;Robertson et al. 2013;Kaiho et al. 2016;Bardeen et al. 2017;Arenillas et al. 2018). Immediately after the event, the marine ecosystem recovered under the "Strangelove Ocean" conditions and the benthic foraminifera re-organized after their drop due to biologic productivity (Rhodes & Thayer 1991;Alegret et al. 2001Alegret et al. , 2002. Prior to the main extinction event, the Oceanic Anoxic Events (OAEs) developed as consequence of shortlived periods of organic carbon burial. These events are distinguished by their pervasive distribution of distinct black shale beds with marked carbon isotopic excursions. The relationship of plankton turnover and carbon isotopic excursions with the major OAEs points to widespread changes in the ocean-climate system. The mid-late Cretaceous was a time of a switch in the character of the ocean-climate system subjecting to increased rates of tectonic activity and shifting paleogeography (Jones & Jenkyns 2001). The OAEs and resultant black shales during
upwelling during the Campanian. The subsequent erosion and its re-deposition shaped the platform, evolving it from relatively steeper ramp geometry in the Campanian to gentler epeiric ramp in the Selandian and Thanetian, and triggered deposition of shallow ramp larger benthic foraminiferal facies. The boundary is similar in nature with erosional phase in the whole region but its duration was prolonged in the study section and its upper limit has some regional changes. As finding of this study, the late Cretaceous "Nara Sandstone Member" of the Kawagarh Formation in Hazara area of earlier workers could be revised as Paleocene Hangu Formation.

GEOLOGICAL SETTINGS
The late Cretaceous strata in the Indus Basin of Pakistan was part of the temperate carbonate platform system along the southern margin of the eastern Tethys Ocean. The study area is part of the lesser Himalayas ( Fig. 1)  Hangu Formation at Dhudial (34°10'01"N, 73°39'86"E), north of the city Abbottabad (34°09'21"N, 73°13'10"E) and of the capital Islamabad in northern Pakistan. The Cretaceous unit is composed of medium to thick bedded limestones, which are dark grey on fresh surfaces and bluish to pale yellow on weathered surface and bear some intercalation of marls. The lower part of Paleogene (Hangu Formation) is comprised of lateritic sandstones with ferruginous cements, interpreted as exposed deltaic plains (Warwick et al. 1995;Munir et al. 2005;Shah 2009). The Hangu Formation in adjacent areas like Balakot and Azad Kashmir, as per Munir et al. (2005), with 1-26 meters thickness variation, has records of laterites, pisolitic bauxites, carbonaceous shales and coal seams, conforming with the transitional marine/deltaic environment. whereas its upper part is represented by larger benthic foraminiferal sandy limestones. Since the Dhudial Section is located in the lesser Himalayas of the intensely deformed Himalayan fold and thrust belt, earlier researchers were reluctant to carry out noteworthy analysis. Very less literature review is available by researchers and their work is restricted to pioneer values. The noteworthy ones include Latif (1970), Ahsan et al. (1993) and Shah (2009), who worked on facies variations in the early Paleocene, lithostratigraphy of the southern Hazara and the occurrence of oolitic hematite, marking the K-T boundary.

MATERIAL AND METHODS
The Dhudial Section (Fig. 3) is located 5 km north of Abbottabad City on the Abbottabad-Thandiani road, where it is excellently exposed along a quarry comprising of late Cretaceous-Paleocene rock units ( Fig. 4A-C). A total of 40 samples were collected from the Dhudial Section at regular intervals of 2 meters. Each sample from limestones/marly limestones was cut into two pieces, one of which was retained while other was processed using the freeze-thaw method of Slipper (1996) in which the trampled samples were immersed in a supersaturated solution of Na 2 SO 4 . The process was repeated 2-3 times, washed and passed through and 63 µm sieve till foraminiferal    (2008) were used for interpretation of sequence stratigraphic analysis. A total of 28 planktonic foraminiferal species were identified following methods of Robaszynsky & Caron (1979) and Caron (1985).

hangu Formation
The 3-meter thick sandstone lithofacies of the Paleogene is hard, compact and characterized by a light brown color. In addition to quartz and feldspar, chert rock fragments and accessory minerals such as mica (muscovite) are obvious. Quartz (Fig. 5I) is most dominant, majority of which is monocrystalline and sub-angular to sub-rounded. The feldspar grains belong to the K-feldspar group, medium to coarse sand size with well-rounded boundaries (Fig. 5J). Lithics of chert ( Fig. 5K) are present whereas accessory minerals include muscovite mica and some ore minerals. They are sub-spherical to sub-rounded boundaries. The constituents are clustered by a combination of quartz overgrowths, interstitial calcite cements, and ferruginous matrix (Fig. 5L). This moderately sorted, fine grained sandstone is texturally and chemically sub-mature as indicated by the abundance of grains/matrix and Q/F ratios rock term the rock as sub-arkose. Dominance of monocrystalline quartz, some chert fragments and highly rounded grains indicate a dominantly igneous and sedimentary source. The overlying 2 m bed of sandy foraminiferal limestone facies yield angular to sub-angular siliciclasts and skeletal allochems embedded in a mix of matrix and sparry calcite cement. Skeletal allochems are partially micritized and include Lockhartia (Davies 1932), Globanomalina (Haque 1956) and miliolids. Upwards gradation of facies into pure foraminiferal limestones has been recorded in the Thanetian Lockhart Formation of Hanif et al. 2013).

ForaminiFeral biostratigraphy
The late Cretaceous biostratigraphic correlation on planktonic foraminifera has received attention due to presence of significant microfossils in deep marine sequences. Early studies conducted by Eicher (1969Eicher ( , 1972 formed a critical framework for the planktic foraminiferal biostratigraphy and paleoecology whereas Leckie (1989) considerably developed its paleoclimatic and paleo-oceanographic applications. Regarding the preliminary biostratigraphic framework in the study area, Latif (1970) reported Coniacian-Campanian foraminifera in the Changla Gali Section of Hazara area this being confirmed by Butt (1992). Due to the structural complexities, limited work has been conducted and the current Dhudial Section provides the best exposure to date of late Cretaceous-Paleogene strata in the region, not described before. This study describes the presence of Cenomanian-Early Campanian planktic foraminiferal species ranges and applies it on the standard planktic foraminiferal biozones of Robaszynsky & Caron (1995) to achieve long range correlations. The range chart based on abundance, diversity, FADs and LADs of different foraminifera (Fig. 6) recognize eight different biozones. These biozones include: 1) Rotalipora reichel zone; 2) Rotalipora cushmani zone; 3) Whiteinella archaeocretacea zone; 4) Helvetoglobotruncana helvetica zone; 5) Marginotruncana sigali zone; 6) Dicarinella concavata zone; 7) Globotruncana elevata zone; and 8) Globotruncana ventricosa zone; they have been marked in Figure 8.
, occurs between the demise of G. bentonensis and the onset of Heterohelix species such as H. Moremani (Cushman 1938) and H. reussi (Cushman 1938) in the Dhudial Section. The uppermost Heterohelix moremani sub-zone marks FAD of heterohelix shift to the first appearance of Helvetoglo-   (Klaus 1960  The present study depicts that deposits above the early Campanian have experienced an abrupt change of fauna from late Cretaceous planktonic to Paleocene benthic. The Paleocene genera of Lockhartia (larger benthic) and Globanomalina (smaller benthic) in the sandy foraminiferal limestone bed, above the sandstone unit, manifest a faunal change. The lateritic? ferruginous sandstone unit, located between 70 and 73 m (Fig. 3), and subsequent sandy foraminiferal limestone bed overlying the late Cretaceous beds and underlying the late Paleocene foraminiferal limestones remains undated. Khan & Ahmad (1966) and Shah (2009) have called the upper sandstones of the Cretaceous Kawagarh Formation in Hazara area as "Nara Sandstone Member" and correlated them with the Maastrichtian Pab Sandstone in the Sulaiman Ranges. However, this correlation was merely on facies basis, lacked any sort of evidence and appears to have an age assignment problem. The absence of Maastrichtian fauna in the Kawagarh Formation of the studied Dhudial Section and overall, in the Hazara area makes the correlation of this sandstone unit with the Maastrichtian Pab Sandstone dubious. The gradational contact of this sandstone with middle Paleocene foraminifera bearing sandy limestone bed and conformable presence of Thanetian foraminiferal limestones (Lockhart Formation) of Hanif et al. (2013) positions the unit in Selandian. Using nannofossils, dinoflagellates and pollens samples from the Salt Ranges, Köthe (1988) and Warwick et al. (1995) have confirmed middle Paleocene (Selandian) age for the Hangu Formation. Thus, the late Cretaceous "Nara Sandstone Member" of Kawagarh Formation in Hazara area of Khan & Ahmad (1966) and Shah (2009) could be revised as middle Paleocene Hangu Formation. Though the main extinction event started well before the onset of Paleocene, the absence of Maastrichtian and Danian fauna in the Upper Indus Basin hinders the establishment of the K-Pg boundary on faunal record. Due to these reasons, the boundary zone is marked on basis of facies change, and correspond to the sandy ferruginous bed interval between 70 and 73 m at the base of the Hangu Formation, this being supported by the appearance of middle Paleocene benthic fauna immediately above.

paleoecology
The spatial distribution and abundance of planktonic foraminiferal assemblages are associated with sea water stratification, vertical changes in temperatures and density gradients (Keller 2002;Price & Hart 2002). Based on the foraminiferal assemblages, the upper euphotic zone, lower euphotic zone, disphotic deeper water zones have been established (Fig. 7). The keeled species have generally been assigned deeper water paleoecologic requirements (Norris & Wilson 1998;Leckie et al. 2002).
The keeled genera of rotaliporids, globotruncanids and marginotruncanids, representing deeper oligotrophic waters

Facies analysis
The sediments in most part of the Dhudial Section are composed of fine grained limestones below the K-Pg boundary zone interval, and sandstones and sandy limestones above. The lower part of the Dhudial Section is occupied by late Cretaceous planktonic foraminiferal wackestone, spanning the Cenomanian and lower Turonian stages, and contains relatively deep water (near thermocline) fauna such as Rotalipora, Heterohelix, Hedbergella, Dicarinella, as well as Marginotruncana (in middle part of the formation). The facies is attributed to have been deposited in middle bathyal depths, the breaking of thermocline effectively eliminating the deeper dwelling species. Following the demise of deep dwelling fauna like Rotalipora on maximum sea levels (Leckie 1989), the intervening zone with upper euphotic zone fauna could suggest lowered sea levels. This can be inferred from the extinction of deepsea benthic foraminifera across the Cenomanian-Turonian Boundary (Kaiho 1998). The relatively high diversity of the biota in the intervening zone (Fig. 8) suggests loss of water stratification and thorough mixing of the nutrients, reaching to various parts in the ocean depth profile (Hays et al. 2005).
Patches of foraminiferal packstone texture support the circulation of the waters in middle-distal outer ramp environment. The radiolarian rich wackestones occur as transitional bed (31-38 m) between the lower foraminiferal wackestones and overlying foraminiferal lime mudstones during middle to late Turonian. Two environments of deposition have been suggested for this radiolarian-rich facies with different causes: 1. Middle to outer ramp due to the absence of deep waters planktonic foraminiferal fauna and presence of low salinity tolerant Hedbergella planispira. The high levels of dissolved silica may be due to the growth of the Kohistan Island Arc within Tethys during late Cretaceous could therefore probably explain the bloom of radiolarians 2. Open marine/bathyal (lower euphotic zone) associated with the possible presence of OAE3 in the Coniacian-Santonian time periods (Arthur et al. 1990) or latest Turonian Hitchwood event of Jarvis et al. (2006) in sections including Tethys when primary plankton resource was on a high (Bomou et al. 2013;Leckie et al. 2002). The later one is suggested because of possible presence of organic rich deposits (Fig. 4C) but absence of deep dwelling planktonic foraminifera makes the interpretation ambiguous. Because of the long-ranges and ocean-wide distribution, the radiolarites apparently characterize anachronistic facies, but stepwise extinctions and constant radiations precede and follow the events (Erbacher & Thurow 1997). Leaching of nutrients during drowning events and development of reactive Fe limitation led to an increased productivity, an expanded oxygen minimum zone (OMZ), and amplified organic matter preservation at the inception of OAE3. Whereas this loss of deep habitat reduced the deeper dwelling forms, it allowed the shallower radiolarians to thrive (Erbacher & Thurow 1997). Likewise, the expanded oxygen minimum zone at the OAE's also destroy the deeper habitats of the planktonic foraminifera, and though this assumption has been well established for the OAE2 by Erbacher et al. (1996), the same can also be considered for the probable OAE3 facies. Considering the radiolarians as shallower coupled with general absence of deep dwelling foraminifera, the current facies can be explained according to Erbacher & Thurow (1997) and Erbacher et al. (1996). Conversely, rapid submarine eruptions offer a viable alternative for traditional climatic scenarios for high productivity of silica that are irrelevant to greenhouse-to-icehouse climatic change (Racki & Cordey 2000). Therefore, the possible volcanic activity in the Kohistan Island Arc within the eastern Tethys, explaining for nurturing of radiolarians, can advocate for the first interpretation as well. Radiolarian's occurrence and partial disappearance of foraminifera has also been reported from the Coniacian Niobrara Formation, Canada (Diaz & Velez 2018), comparable with the Coniacian radiolarians of Pugh et al. (2014) in the Sverdrup Basin, Arctic Canada. They believed that the high supplement of silica due to volcanic events favored the paleoecological conditions for radiolarians to flourish. Regarding the OAE3, which is the least known amongst all events of the Cretaceous, its development and paleoenvironments were dependent on regional or local conditions (Bomou et al. 2013). Even though Wagreich (2012) has reported local organic rich layers in Pakistan (location not mentioned) but he generally considered that the OAE3 organic deposits are largely absent from the Tethys. He assumed the OAE3 does not define a single distinct time period, spanned over a longer period and occurred in different basins in different times. The organic rich horizon of present study could either represent the Hitchwood Event of Jarvis et al. (2006) or possibly linked with OAE3 of Wagreich (2012) because of the longer duration of the event. However, further studies are required to better support the assumption. The upper part of the late Cretaceous is marked by foraminiferal lime mudstones representing relatively shallower deposition during Coniacian to middle Santonian, and deeper till early Campanian; according to the occurrence of globotruncanids at this level. The facies is in contact with planktonic foraminiferal wackestones with an intervening ferroan dolomitized boundary, attributed to migration of fluids along bedding planes and stylolitized sutures. Facies over the K-Pg boundary are markedly different i.e. fine-medium grained sandstones with ferruginous matter, calcite and silica cements. Unfortunately, the boundary zone does not bear any characteristic sedimentary structures, probably due to the extreme thin nature of the zone, it does have a yellowish to brownish lateritic horizon with developed   crystals of authigenic quartz. The texturally and chemically sub-mature sub-arkose, and moderate sorting suggest transitional marine (deltaic) environment shaping the grains into sub-angular to rounded outlines. The fine-grained, sub-arkosic texture and ferruginous nature, is supported by the laterites and bauxites of Munir et al. (2005), in the lower part, in continental-transitional marine environment. The deposits have been considered as residual by Umar et al. (2015), following intense chemical weathering of the exposed Kawagarh Formation. Elsewhere, in sections located outside the domain of the studied area, the basal parts of Hangu Formation have presence of paleosol horizons, red beds and pisolitic bauxites of Warwick et al. (1995), Danilchik & Shah (1987), Whitney et al. (1990. The widespread presence of exposed facies in the region rationalizes the continental-marginal marine paleo deposition for the facies of Hangu Formation. Dominance of monocrystalline quartz, presence of feldspars, some chert fragments and shapes of quartz grains indicate a dominantly igneous and sedimentary source rock. The upward gradation into sandy limestones, bearing Paleocene larger benthic foraminifera (LBF) such as Lockhartia, Globanomalina and miliolids, portray an inner shelf (lagoonal) depositional environment. The facies and fauna depict a sudden shift in the paleogeography from relatively steeper ramp type geometry in the early Campanian to shallow epeiric ramp (Fig. 9) in Selandian and Thanetian as manifested by the siliciclastics (Hangu Formation of this study) and widespread carbonates of the Lockhart Formation of Hanif et al. (2013). The morphometric change in ramp profile is believed to be because of deposition of the erosional load, during Campanian-Selandian, in deeper parts of the basin, making angle of the ramp gentler.
Continued deposition led to a much gentler ramp to almost an epeiric platform by the Thanetian; subsequently depositing the Lockhart Formation. The intervening lower lateritic sandstone bed of the Hangu Formation, represents an erosional phase and consequent shallower deposition. The facies below the K-Pg boundary zone interval in other regional sections have been reported by different workers. According to Shah (2009), the late Cretaceous facies, towards the west and southwest in the Kohat Plateau and Trans-Indus Ranges (Fig. 2), shows a deepening trend with marls and calcareous shales as its elements. Latif (1970) in Hazara area (Dhudial Section located in), and Butt (1992) in western sections, have reported Coniacian to Campanian planktonic foraminifera. Further deep towards the southwest, in the Sulaiman Range, the late Cretaceous unit of creamy white micritic and porcelaneous Parh Limestone is linked with the Kawagarh Formation (Butt 1992;Shah 2009;Khan 2013). Butt (1992) suggests a major transgression during the Coniacian-Campanian followed by a shallowing trend in late Campanian. This late Campanian regression (early Maastrichtian of Khan 2013) in Sulaiman Range is marked by carbonate breccia and presence of thick mixed siliciclastics of Mughal Kot Formation which have an overlying unconformable contact with the Paleocene strata with an intervening laterite (Shah 2009). Thus, the overall absence of late Campanian and Maastrichtian strata are conjunct with the findings of the present work. Converse to the west and southwest, the whole of late Cretaceous is absent in the southern section's such as the Salt Ranges (Fig. 2) and the Tertiary sediments lie directly on the early Cretaceous or older rocks along a major (late Jurassic-Paleogene) hiatus. Whether or not this hiatus has any relationship with the Campanian-Selandian hiatus of present study but it is likely that uplift due to hot spot development of Garzanti & Hu (2014) during the Campanian triggered erosion of the older rocks and developed a major unconformity. In the Ladakh Himalaya (northwestern India), the facies below the K-Pg are represented by the typical basinal Kan Ji Formation characterizing Campanian-Maastrichtian terrigenous detritus as dark marls, mudstones and Zoophycus bearing sandstones (Green et al. 2008). This basinal unit, compared with the late Cretaceous of Pakistan, has a late Maastrichtian top part comprising shallow marine mixed-siliciclastic sediments (Marpo Limestone), cross bedded Danian sandstone (Stumpata Quartz Arenite) and late Paleocene Dibling Limestone with abundant smaller benthos (Green et al. 2008). This shallowing upward facies at the Maastrichtian-Danian hiatus could be correlated with the Campanian-Selandian hiatus of the current study, however, in Hazara area, the hiatus duration was a bit longer. The late Paleocene Dibling Limestone conforms with the transgression during Thanetian that also deposited the Lockhart Formation of Hanif et al. (2013). Further east in the Garhwal Himalayas, Utarrrakhand, India, the shallow marine oomicritic limestones of late Cretaceous Nilkanth Formation (Najman et al. 1993) has contact with late Paleocene-Early Eocene Subathu Formation. The contact is marked by a thin (1.8 m) paleosol horizon with plant rootlets and is almost similar in duration to the present study. Wan et al. (2007) has described late Cretaceous (Maastrichtian) Qubeiya Formation, a conglomeratic sandstone (Quxia Formation) along a hiatus in the southern Tibet, China. In the absence of age diagnostic fauna, Wan et al. (2007) have 'tentatively' placed the Quxia Formation in Danian, above which the lies Thanetian Jialazi Formation with interbedded conglomerates and limestones at its base. The pause in sedimentation of current study conforms with the Campanian break of Garzanti & Hu (2014) in the Dibling Section, Zanskar Range in Kashmir, located towards the west, not far away from the study area. These Cretaceous-Paleogene hiatuses closely matches with the present data, inferring about the widespread nature and duration of the unconformity not only in in the Pakistani and Indian Himalayas but also in southern Tibet, China.

sea level Fluctuations and sequence stratigraphic changes
The relatively warm climate of the Cretaceous period, owing to abundant CO 2 levels and other multiple reasons (Tabara et al. 2017), was associated with elevated eustatic sea levels across the globe. The late Cretaceous has recorded extensive deposits of chalks, marls, planktonic limestones and development of oceanic anoxia (OAE1, OAE2 and probable OAE3) leading to development of black shales around the world (Leckie et al. 2002;Jenkyns 2003;Hofmann et al. 2003;Sageman et al. 2006;Voigt et al. 2008). The Dhudial Section represents second GEODIVERSITAS • 2021 • 43 (18) order cycle in which the Cenomanian-Turonian boundary is associated with the OAE2 in response to increased emissions of greenhouse gases due to extreme volcanism, and reduction in supply of cold oxygenated bottom waters. However, the OAE2 could not be traced on the outcrop due to absence of organic rich facies and the OAE2 is plausibly marked on the basis of extinction of rotaliporids. The intervening rotalipora bearing planktonic lime mudstone beds (at 12m  (1985)

CONCLUSIONS
Sediments deposited in the lesser Himalayas of Pakistan were thoroughly investigated for biostratigraphic, sequence stratigraphic and facies analyses in the Dhudial Section There is a marked contrast in the facies across the K-Pg boundary zone interval; facies below represent open marine planktonic foraminiferal limestones dated from the Cenomanian to the early Campanian. These late Cretaceous beds are sharply truncated by erosion and followed by deltaic siliciclastics and marine sandy limestones, the latter being of middle Paleocene age. An early Campanian to middle Paleocene hiatus is thus evidenced. The change is also evident in faunal turnover from planktonic foraminifera to larger benthic foraminifera across the boundary zone interval. The study proposes to revise the "Nara Sandstone Member" of the upper part of the late Cretaceous Kawagarh Formation in Hazara area as Paleocene Hangu Formation and making its correlation with the Maastrichtian Pab Sandstone in the Sulaiman Ranges as debatable. On faunal basis, the lower part of the Dhudial Section represents deeper oligotrophic waters which were extinct due to development of oxygen minimum zones possibly related to OAE2, although no organic-rich interval is evidenced here. A brief period of upper photic zone was followed by large scale deeper disphotic zones abrupted by oxic zones during lowered sea levels in early Campanian. Though lower part of the Dhudial Section (Kawagarh Formation) has been deposited during TST, middle portion dominantly represents the HST. The upper portion belonging to the TST is headed by deposits of Selandian Hangu Formation of LST and late Thanetian Lockhart Formation of TST. The middle and upper parts of Kawagarh Formation bear radiolarian rich limestones, the middle one is associated with an overlying organic rich bed. These radiolarian rich beds are believed to have been deposited in response to high levels of dissolved silica due to the growth of the Kohistan Island Arc within Tethys during the late Cretaceous. However, an origin with open marine environment, associated with the possible presence of OAE3 in the Coniacian-Santonian time periods or latest Turonian Hitchwood event when primary plankton productivity was on a high, is preferred. The abrupt change in facies is due to sea level falls and associated erosion, resulting in absence of Maastrichtian and Danian fauna and the K-Pg boundary encounters on top of the early Campanian beds, just below the sandy limestone beds of Hangu Formation of Paleocene (Selandian) age.