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Research article Proceedings of the Yorkshire Geological Society Published online July 16, 2020 https://doi.org/10.1144/pygs2019-017 | Vol. 63 | 2020 | pp. 88–123

Cretaceous Oceanic Anoxic Event 2 in eastern England: further palynological and geochemical data from Melton Ross

Paul Dodsworth1*, James S. Eldrett2 and Malcolm B. Hart3 1 StrataSolve Ltd, 15 Francis Road, Stockton Heath, Warrington WA4 6EB, UK 2 Shell International Exploration and Production B.V., Lange Kleiweg 40, 2288 GK Rijswijk, Netherlands 3 School of Geography, Earth and Environmental Sciences, Plymouth University, Drake Circus, Plymouth PL4 8AA, UK PD, 0000-0002-8895-9472; MBH, 0000-0002-5649-8448 * Correspondence: [email protected]

Abstract: The lowermost 1.45 m of the Welton Chalk Formation, including the regional sedimentary record of Oceanic Anoxic Event 2 (OAE-2), has been sampled at Melton Ross Quarry in eastern England, UK. The section is investigated for organic geochemistry and stable isotopes for the first time, while a detailed palynological study follows previously published preliminary results. It comprises a condensed interval that spans the Cenomanian–Turonian Stage boundary. A locally preserved, lower ‘anomalous’ succession (Beds I–VII) and a ‘Central Limestone’ (Bed A) are shown to correlate respectively with the pre-Plenus sequence and Plenus Bed at Misburg and Wunstorf in the Lower Saxony Basin (LSB), NW Germany. They are overlain by a succession of variegated marls (Bed B to Bed H), including the Black Band (Beds C–E), that can be correlated across eastern England. Based on a carbon isotope (δ13C) profile and dinoflagellate cyst and acritarch bio-event correlation, Beds B–H appear to be a highly attenuated post-Plenus equivalent of the LSB succession, including part of the ‘Fish Shale’. The δ13C profile shows possible ‘precursor’/‘build-up’ events in the lower succession at Melton Ross, with the main OAE-2 δ13C excursion occurring in the Central Limestone and overlying Beds B–H. The darker coloured marls from the Black Band and Bed G contain 1.43–3.47% total organic carbon (TOC), hydrogen index values of 78–203 mg HC/g TOC and oxygen index values of 15–26 mg CO2/g TOC, indicating type III and type II–III organic matter, of mixed terrigenous and marine algal sources. The corresponding palynological assemblages are dominated by marine dinoflagellate cysts, comprising mainly gonyaulacoid taxa, with subordinate terrigenous miospores, mainly gymnosperm bisaccate pollen, consistent with a distal marine setting. The interbedded lighter-coloured marls contain less than 0.4% TOC and lower proportions of miospores and peridinioid dinoflagellate cysts compared with the darker layers. This is suggestive of moderately raised levels of productivity during deposition of the darker layers, possibly related to greater nutrient availability from land-derived sources. The occurrence of the peridinioid taxa Eurydinium saxoniense and Bosedinia spp., together with higher proportions of prasinophyte phycomata in the darker layers, may also point to stimulation of organic-walled phytoplankton productivity by reduced nitrogen chemo-species encroaching the photic zone, possibly by expansion of an oxygen-minimum zone. Exceptionally high concentrations of palynomorphs (in the tens of thousands to lower hundreds of thousands per gramme range) in the darker layers at Melton Ross and eight other eastern England localities is consistent with increased quality of seafloor preservation in a low oxygen environment, coupled with a high degree of stratigraphic condensation. Two new dinoflagellate cyst species are described from Melton Ross, Canninginopsis? lindseyensis sp. nov. and Trithyrodinium maculatum sp. nov., along with two taxa described in open nomenclature. Supplementary material: One pdf file, with detailed sample positions and descriptions, tables of supporting information (also available in Excel format), quarry photographs and a palynological distribution chart, is available at https://doi.org/10.6084/m9. figshare.c.4987205 Received 30 October 2019; revised 20 May 2020; accepted 20 May 2020

The Late Cretaceous Epoch was characterized by sustained global anoxic conditions (Jenkyns 2010 and references warm climate, resulting in high eustatic sea-levels (Miller therein). However, the deposition of dark-coloured, organic- et al. 2005; Haq and Huber 2016; Hay et al. 2018). rich, fine-grained sediments (‘black shales’) varied both Numerous epicontinental seaways became established, temporally and spatially, being modulated and ultimately submerging large areas of Western Europe (e.g. Gale 1995) dependent on local and regional processes (basin restriction, and the Western Interior of North America (Kauffman and water stratification, bottom-currents, sediment input) in Caldwell 1993). Major global perturbations in the carbon addition to global phenomena (Large Igneous Province cycle occurred, termed Oceanic Anoxic Events, the most activity, sea-level change, orbital forcing; e.g. Ernst and prominent spanning the Cenomanian–Turonian Stage Youbi 2017; Clarkson et al. 2018; Minisini et al. 2018). A boundary (CTB, 93.9 Ma; International Commission on global mass extinction/turnover bio-event occurred around Stratigraphy 2019), named OAE-2 (Schlanger and Jenkyns the CTB and is probably associated with OAE-2 (Raup and 1976; Schlanger et al. 1987) and lasting for up to c. 900 kyr Sepkoski 1982, 1984; Kauffman 1984; Milne et al. 1985; (Eldrett et al. 2015a; Gangl et al. 2019). This interval was Hart 2005, 2019). marked by a globally recognized positive carbon isotope In the North Sea Basin and adjacent outcrop areas in NW (δ13C) excursion, reflecting the widespread sequestration of Germany and eastern England, UK, deposition of dark δ12C-enriched organic matter in marine sediments under coloured mudstones interbedded with light coloured mudstones

© 2020 The Author(s). This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 License (http://creativecommons.org/ licenses/by/4.0/). Published by The Geological Society of London for the Yorkshire Geological Society. Publishing disclaimer: www.geolsoc.org.uk/pub_ethics Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

Melton Ross palynology and geochemistry 89 and limestones commenced during the Late Cenomanian, and maximum eustatic sea-levels being reached during the continued into the Early Turonian in some areas, including Early Turonian (Haq et al. 1988; Sahagian et al. 1996; Wunstorf and Misburg in the Lower Saxony Basin, NW Miller et al. 2003, 2005). They were probably the time of Germany (Fig. 1). At these locations, the CTB succession is minimal continental relief during the Phanerozoic and the 12–30 m thick (Ernst et al. 1983; Hilbrecht 1986). The dark time of minimal detrital sediment delivery to the ocean (Hay mudstone layers form a distinctive interval in predominantly et al. 2018). The CTB interval was also a time of extreme whitish limestone chalk successions. In eastern England warmth with mid-latitude sea-surface temperature possibly (Fig. 2), a highly condensed (relative to NW Germany) exceeding 35°C (Huber et al. 2002; Voigt et al. 2004; Forster ‘Black Band’ has developed in Yorkshire (0.3–0.7 m thick at et al. 2007; Robinson et al. 2019 ). This warmth was likely Flixton, East Knapton, Bishop Wilton and Market Weighton; associated with a more stratified water column, resulting in Jeans et al. 1991; Dodsworth 1996) and northern Lincolnshire poor atmosphere–ocean gas exchange, oxygen-deficient (0.1–0.2 m thick at South Ferriby, Elsham, Melton Ross, Bigby photic zone waters, including euxinic conditions in some and Caistor). Jenkyns (1985) envisaged a pelagic shelf regions, and enhanced organic matter preservation at the depositional setting for the Black Band and adjacent strata in sediment–water interface (Sinninghe Damsté and Köster a relatively shallow (several hundred metres) epicontinental sea. 1998; Monteiro et al. 2012). Rhythmic bedding in CTB The Black Band wedges out to the south of Louth (Hart et al. successions has been linked to orbital-forcing (e.g. Arthur 1991). It appears to represent the ‘feather-edge’ of OAE-2, et al. 1986; Eldrett et al. 2015b; Boulila et al. 2020), which in which dies out when traced towards a palaeohigh that appears some regions, including NW Germany, may have caused an to have been located in the region of the Wash (Hart et al. intensified hydrological cycle during warmer/wetter periods 1991). Schlanger et al. (1987) suggested that it may have been (van Helmond et al. 2015; Charbonnier et al. 2018; Gharaie deposited near the upper limit of an oxygen-minimum zone that and Kalanat 2018). lapped on to the continental shelf. The early stages of OAE-2 were characterized by a The Cenomanian and Turonian stages probably record the relatively extended interval (c. 150–200 kyr; Clarkson et al. highest sea-levels within the Cretaceous Period, with 2018)ofc. 3–5°C cooling of sea surface temperatures in the

Fig. 1. Turonian palaeogeographic reconstruction with the main Northern Hemisphere site locations discussed in the text: brown shaded area, landmass; light blue, palaeoshelf; CLIP, Caribbean Large Igneous Province; HALIP, High-Arctic Large Igneous Province. Modified from Eldrett et al. (2014, 2017) and Du Vivier et al. (2015). Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

90 P. Dodsworth et al.

Fig. 2. The Cretaceous outcrop in eastern England and the location of sections discussed in the text (modified from Hart 2019). The Black Band wedges out to the south of Louth (line A–A). It appears to represent the ‘feather-edge’ of OAE-2 when traced towards a palaeohigh located in the region of the Wash. Between lines A–A and B–B the chalks and nodular chalks of latest Cenomanian–earliest Turonian age are dull red in colour, while south of line B–B the chalks at the same stratigraphic level are pale green/grey in colour. proto-Atlantic and the European shelf (Forster et al. 2007; and SE France (e.g. Pont d’Issole, Fig. 1), ‘black shale’ Pearce et al. 2009; Sinninghe Damsté et al. 2010; Jarvis et al. deposition temporarily gave way in some areas to more 2011; van Helmond et al. 2014, 2015). Boreal realm fauna, oxygenated sediments during the PCE, and a resumption of including the belemnite Praeactinocamax plenus deposition of relatively thick biogenic pelagic limestones (Blainville), migrated southwards across Europe (Jefferies (Wiese et al. 2009; Jarvis et al. 2011; Grosheny et al. 2017; 1962, 1963; Gale and Christensen 1996; Marcinowski et al. Jenkyns et al. 2017). In NW Germany, a conspicuous 1996; Košták et al. 2004). The interval was termed the tripartite limestone bed, called the Plenus Bed or Plenus Bank ‘Plenus Cold Event’ (PCE) by Gale and Christensen (1996) because it yields the eponymous belemnite, is developed at and probably marks a shift towards improved oxygenation of this level (Ernst et al. 1984; Hilbrecht and Dahmer 1994), bottom waters during OAE-2 (Forster et al. 2007; Eldrett separating underlying pre-Plenus and overlying post-Plenus et al. 2014, 2017; van Helmond et al. 2014), possibly on a successions of dark coloured mudstones interbedded with global scale (Clarkson et al. 2018; O’Connor et al. 2020), and light coloured mudstones and limestones. relatively drier climates (Heimhofer et al. 2018; Gharaie and Wood and Mortimore (1995) and Wood et al. (1997) Kalanat 2018). Across regions of Europe that record organic- reported the CTB succession from Melton Ross Quarry in rich sedimentation during OAE-2, including NW Germany Lincolnshire (Fig. 2). Temporary deep excavations in the late Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

Melton Ross palynology and geochemistry 91

1990s (Fig. 3) exposed a section hitherto unreported in nannofossils) during the CTB mass extinction (Jarvis et al. eastern England, presumed eroded by unconformity else- 1988a; Lamolda et al. 1994; Paul and Mitchell 1994; Hart where, that appears to correlate with the lowermost 2–3mof 1996). This paper provides the first detailed palynological the NW Germany CTB succession, including the pre-Plenus data from Melton Ross and attempts to discriminate the interval and the Plenus Bed. These deposits are overlain by relative contribution of these factors. A taxonomic review of the regionally correlative Bed B, Black Band and Beds F–H new and problematic dinoflagellate cysts is included. Other (Fig. 4). marine palynomorphs are documented, including prasino- In a recent review of the Black Band, Hart (2019) phyte phycomata and acanthomorph acritarchs, along with discussed advances in foraminiferal knowledge a quarter of a land-derived (terrigenous) pollen and spores. For regional century after previous publications on their distribution comparison, summary palynological data are published for across the CTB in eastern England (Hart and Bigg 1981; Hart eight correlative eastern England localities. From south to et al. 1993). The present paper follows up on this work, north, these are Caistor, Bigby, South Ferriby, Market reviewing advances in palaeoenvironmental knowledge and Weighton, Bishop Wilton, East Knapton, Flixton and biostratigraphic dating using organic-walled phytoplankton Speeton (Fig. 2). Total organic carbon, Rock-Eval pyrolysis since this was last discussed for eastern England in the and stable isotope data are presented for the first time from publications of Dodsworth (1996, 2000) and Wood et al. Melton Ross. The integrated bio- and chemostratigraphy of (1997). Previous analysis of palynological recovery from the the section is assessed in an inter-regional context. Black Band at South Ferriby and Flixton (Hart et al. 1993; In this paper, chronostratigraphic substages and their Dodsworth 1996) has revealed exceptionally high concen- corresponding ages are treated as formal units, using initial trations of dinoflagellate cysts, in the thousands to lower upper case letters, consistent with the usual practice, hundreds of thousands per gramme range. Hart and although not all have been ratified. The base of the Koutsoukos (2015) recommended further investigation of Cenomanian Stage and Lower Cenomanian Substage have whether the abundance of dinoflagellate cysts is a function of a ratified Global boundary Stratotype Section and Point their increased productivity under eutrophic conditions, (GSSP) at Mont Risou in southern France (Kennedy et al. increased quality of seafloor preservation in a low oxygen 2004). The base of the Turonian Stage and Lower Turonian environment, or a normal level of organic productivity Substage have a ratified GSSP near Pueblo, Colorado (Fig. 1; accentuated by a loss of biogenic carbonate sediment Kennedy et al. 2005). The base of a Middle Cenomanian (including planktonic foraminifera and calcareous Substage has a proposed GSSP in Sussex, southern England

Fig. 3. Sketch map of Melton Ross Quarry, north Lincolnshire, showing the position of the Cenomanian–Turonian boundary (CTB) succession excavations in 1997 (after Wood et al. 1997). Site 1 and Site 4 sampling exposures (located around 53° 35′ 14′′ N, 0° 22′ 32′′ W at 19 m above sea-level) are currently (2019) buried c. 10 m below the restored surface of the quarry. Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

92 P. Dodsworth et al.

Fig. 4. Composite lithological log of the sampled Melton Ross Quarry section with carbon and oxygen isotope curves. Biostratigraphy: 1, planktonic foraminiferal zones extrapolated from Elsham and South Ferriby (Hart and Bigg 1981; Hart and Leary 1989); 2, 3, dinoflagellate cyst zones and subzone of Olde et al. (2015a) and Dodsworth and Eldrett (2019). Formations of Wood and Smith (1978). Members of Jeans (1980); Mitchell (2000) and Hopson (2005; new sub-member rank). The Buckton Member is ‘The Inoceramite’ of Hart et al. (1991, 1993) and Hart (2019). Local beds I–VII of Wood et al. (1997), regional Beds A–HofDodsworth (1996), Turnus Bed of Pomerol and Mortimore (1993), ‘Adrian’s Pair of Marls’ of Mortimore (2014), Central Limestone of Wood et al. (1997) and Hildreth (1999), Black Band sensuWood and Smith (1978). Distribution of the belemnite Praeactinocamax plenus was reported from Site 1 at Melton Ross by Wood et al. (1997). OAE-2 is picked based on relatively high δ13C values of greater than 3‰ VPDB in this section. Points ‘a’, ‘b’ and ‘c’ are tentatively correlated with the corresponding southern England picks of Jarvis et al. (2006), allowing tentative positioning of CTB around the Bed F/G boundary. Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

Melton Ross palynology and geochemistry 93

(Tröger et al. 1996) and that of a Middle Turonian Substage based on chemostratigraphy (stable carbon isotopes: Schlanger is proposed near Pueblo (Bengtson et al. 1996; Kennedy et al. 1987; Hart et al. 1991; Gale et al. 1993; Wood and et al. 2000; Dodsworth and Eldrett 2019). Tröger et al. Mortimore 1995; and subsequently, Clarkson et al. 2018)and (1996) recommended southern France as a suitable region for macrofossils (e.g. Jefferies 1963; Whitham 1991; Gaunt et al. an Upper Cenomanian Substage GSSP, though they did not 1992; Wood et al. 1997). Hopson (2005) proposed using the propose a site. Replacement of Acanthoceras ammonites by term Plenus Marl Member for marl and limestone beds the genus Calycoceras (Hancock 1991), which can also be between the base of the Welton Chalk Formation and the base correlated using carbon isotopes (Kennedy and Gale 2006), of the Black Band, on the grounds of their probable correlation provides a possible datum for the base of an Upper with the Plenus Marls of the Anglo-Paris Basin. He also Cenomanian Substage. proposed using the term Black Band Member for marls and limestones between the base of the Black Band and the base of the Buckton Member (Mitchell 2000), on the grounds of these Lithostratigraphy deposits probably being stratigraphically higher than the The Late Cretaceous Epoch in England is represented by the Plenus Marls, equivalent to part of the Melbourn Rock bio-micritic, white limestones of the Chalk Group (Fig. 2), Member/Ballard Cliff Member in southern England. which Wood and Smith (1978) grouped into three major However, subsequent workers have retained one unit, the faunal and depositional provinces: a Northern Province Flixton Member of Jeans (1980), for both intervals (Hart 2019; (investigated here), which links eastern England to the north Mitchell 2019). In Table 1, the subdivision of the Flixton of the Wash with contemporaneous North Sea and NW Member into two sub-members (Brett et al. 2018)is German successions; a Southern Province linking southern suggested, based on the definitions of Hopson (2005). England and northern France (Anglo-Paris Basin); and a In the Anglo-Paris Basin, Jefferies (1963) labelled the Transitional Province in the Chilterns and East Anglia. In eight correlative beds of a ‘standard’ Plenus Marls eastern England, chalk bedding is developed on a decimetre succession as Beds 1–8 in ascending order. Any strata that scale with more clay-rich marls forming thin (<5 cm) inter- could not be correlated with these beds were labelled locally beds (e.g. Hancock 1976; Jeans 1980). From Louth northward with lower case Roman numerals. Jefferies (1963) could not in Lincolnshire and Yorkshire, the lowermost c. 0.5 to 1.5 m trace Beds 1–8 farther north than Marham in Norfolk of the Welton Chalk Formation (Wood and Smith 1978)is (Fig. 2), though subsequent work (Voigt et al. 2006) characterized by an atypically thick succession of variegated tentatively identified the uppermost units (Bed 7 and Bed marls, including the organic-rich Black Band (Fig. 4). 8) at Heacham and Barret Ringstead, near Hunstanton. Hopson (2005) gave a comprehensive review of the Jefferies (1963) investigated one locality from Lincolnshire historical naming of the lowermost part of the Welton Chalk (South Ferriby) and another from Yorkshire (Speeton), with Formation, along with evidence for its stratigraphic position, the Black Band assigned to ‘bed i’ at Speeton and ‘bed iii’ at

Table 1. Lowermost part of the Welton Chalk Formation: a comparison of bed nomenclature. Sample positions are indicated Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

94 P. Dodsworth et al.

South Ferriby. Hart et al. (1991, 1993) applied Jefferies’ which contain a thicker lower succession than Site 1, and (1963) informal bed names at South Ferriby. Subsequently, categorized the localized deposits into seven units, Beds I– individual beds within the Flixton Member have been VII. They expressed uncertainty about how Beds III–VI assigned different names by different authors during research correlate with Site 1. At the time of writing (2019), sites 1–4 published in the 1990s (Table 1). Most of these schemes use are buried c. 10 m below the restored surface of the quarry. ascending numbers comparable to the Anglo-Paris Basin In addition, Wood et al. (1997) collected their own set of succession whilst not intending to imply lithostratigraphic 27 samples from Site 2 (labelled CJW-1 to -26) and correlation with southern England beds of the same number. presented rare earth element data, analysis of clay mineralogy To avoid confusion, Dodsworth (1996) alternatively and preliminary palynological comments from those proposed using letters rather than numbers for the eastern samples. They reported shale-normalized rare earth element England succession, and erected a regional lithostratigraphic profiles to be sub-horizontal with no Europium anomaly, scheme of comparable resolution to previous schemes. suggesting to them a detrital rather than volcanogenic In hydrocarbon wells from the central North Sea Basin, provenance for the CTB succession (Wood et al. 1997, fig. e.g. well 47/10-1 (Fig. 2), the distinctive black, grey and 5). They further reported the clay mineralogy to comprise a green lithologies described from the CTB interval (Rhys mixture of illite, kaolinite and smectite at the base of the 1974; Burnhill and Ramsay 1981) are comparable to those succession, but becoming predominantly smectite upwards from the lowermost part of the Welton Chalk Formation of with the loss of kaolinite in the regionally correlative upper onshore eastern England, and contain comparable foramin- succession (Wood et al. 1997, fig. 4). They interpreted this iferal assemblages (Burnhill and Ramsay 1981; Crittenden change in mineralogy as probably suggesting either deepen- et al. 1991) and palynological assemblages (Marshall and ing or increasing distance from shorelines through the CTB Batten 1988; Dodsworth 1996). The term ‘Plenus Marl interval (Wood et al. 1997, p. 339). Formation’ was initially applied to the corresponding high Wood et al. (1997,p.342,fig.3)recovered gamma log-response unit in UK sector North Sea wells by Praeactinocamax plenus from Site 1 at Melton Ross, in silty Deegan and Scull (1977), but this has since been replaced by lithologies immediately above the Central Limestone (Fig. 4). ‘Black Band Bed’ (Johnson and Lott 1993; Surlyk et al. They considered the latter to correlate with the Plenus Bed in 2003; van der Molen and Wong 2007) to reflect lithologies NW Germany. Wood and Mortimore (1995) and Wood et al. and stratigraphy different from that of the Plenus Marls in the (1997) did not publish logs of the chalk section above the Anglo-Paris Basin. Farther north, in the Norwegian sector, variegated marls (Bed B to Bed H) at Melton Ross, i.e. from e.g. well 35/6-2 S (Fig. 1), the term Blodøks Formation (of the upper part of the Flixton Member. This section is logged in Isaksen and Tonstad 1989) is applied to the correlative the present study (Fig. 4) and reveals a thickness of chalk interval developed within the siliciclastic Shetland Group. (0.65 m) between the top of the variegated marls and ‘Adrian’s The Blodøks Formation is usually a few metres thick and pair of marls’ (of Mortimore 2014), immediately below the rarely exceeds 20 m (Gradstein and Waters 2016). base of the Buckton Member, comparable to that at nearby In this paper, the lithostratigraphy of Dodsworth (1996) is South Ferriby and Caistor (Hart et al. 1991,fig.2;Mortimore retained (Fig. 4). Higher resolution subdivision around the 2014,fig.4.23a;Hart 2019,fig.4). Central Limestone (of Wood et al. 1997; Bed A), as described by Wood et al. (1997) and Hildreth (1999) at Previous palynological work Melton Ross Site 2 and some other northern Lincolnshire quarries, including Bigby, are treated here as subdivisions of There have been several previous palynological investiga- Beds A and B (Table 1). In Yorkshire, Beds A and B may tions of the lowermost part of the Welton Chalk Formation. pinch out at some localities, e.g. Bishop Wilton and East R.J. Davey, in Hart and Bigg (1981), reported dinoflagellate Knapton (Dodsworth 1996), and Speeton (Jefferies 1963; cysts to be the dominant palynomorphs at Elsham (Fig. 2), Mitchell et al. 1996; Mitchell 2000), with the Black Band at with subordinate bisaccate pollen and very rare spores. Hart the base of the Welton Chalk Formation or a short distance and Bigg (1981) suggested that marine algae were probably above it, i.e. above an attenuated, 2–12 cm thick Bed B. The the main source of the abundant organic matter in the Black local Beds I–VII of Wood et al. (1997) are applied here to the Band. They also noted that adjacent marls and chalks at lower succession at Melton Ross. Elsham were palynologically barren, probably a function of unfavourable lithologies for the preservation of organic- walled microfossils. A species list and distribution chart were Previous research not provided. Marshall (1983, p. 172–174) and Marshall and Wood and Mortimore (1995) made an initial description of a Batten (1988) undertook detailed analysis of six South relatively expanded stratigraphic succession at Melton Ross Ferriby samples. Cyclonephelium compactum–membrani- Quarry (Site 1; Fig. 3), which exposed a section of marls, phorum was reported to be the dominant dinoflagellate cyst hitherto unreported in eastern England, above the base of the in the Black Band, with sparse recovery of palynomorphs Welton Chalk Formation. The marls are presumed to have from marls immediately below and above (Beds B and F), been eroded by unconformity elsewhere. Wiese et al. (2009) and palynologically barren samples from adjacent chalks. suggested this lower ‘anomalous’ section may have been Microplankton compose 76% of an assemblage from the fortuitously preserved in a down-faulted block, though there lower part of the Black Band (Bed C) and 89% from the is no regional geophysical evidence of such a structure. upper part (Bed E). The Cenomanian marker taxon Wood et al. (1997) described three further Melton Ross Litosphaeridium siphoniphorum was not recorded in any excavations made during 1995–1996 (sites 2–4; Fig. 3), of the samples. Duane (1992, p. 277–292; in Hart et al. 1993) Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

Melton Ross palynology and geochemistry 95 provided palynological data for four productive samples details of the samples). The samples were prepared and from the east wall at South Ferriby quarry (Beds C to G); analysed for organic geochemistry, palynology and carbon- adjacent chalks and marls from c. 75 cm above and 65 cm ate stable isotopes. In the following text, the sample series below were palynologically barren. Cyclonephelium com- prefix is not written out in full for each sample; thus, sample pactum–membraniphorum, along with Eurydinium saxo- MR97-1 is shortened to sample -1. niense, are dominant in the dinoflagellate cyst assemblages of the productive samples, while terrigenous bisaccate pollen Organic geochemistry and spores compose <5% of the total palynological All samples were analysed for total organic carbon (TOC). assemblages. Exceptionally high concentrations of dinofla- Samples with >0.25% TOC (-1 to -11.5, and -22) were also gellate cysts (thousands per gramme), relative to Middle analysed for Rock-Eval pyrolysis. Analyses were undertaken Cenomanian chalks and marls of southern England (hun- in the laboratory of Applied Petroleum Technology (APT) dreds per gramme; Paul et al. 1994), were reported. Duane AS, Oslo, Norway. All procedures followed Weiss et al. (1992;inHart et al. 1993) did not record Litosphaeridium (2000). For TOC, a Leco SC-632 instrument was used. siphoniphorum in any of the South Ferriby samples. Diluted hydrochloric acid (HCl) was added to the crushed Dodsworth (1996) published palynological data from rock samples to remove carbonate. The samples were then three samples of the Black Band from the south wall at South introduced into the Leco combustion oven, and the amount of Ferriby quarry (recovery from adjacent marl samples was carbon in the sample was measured as carbon dioxide (CO ) sparse), six samples from the Black Band at Flixton (splits of 2 by an IR-detector. For Rock-Eval pyrolysis, a HAWK the same samples analysed for geochemistry by Jeans et al. instrument was used. Jet-Rock 1 was run as every tenth 1991), two samples from Bed G at Market Weighton, and sample and checked against the acceptable range given in commented on the palynology of the Black Band at Caistor, Weiss et al. (2000). The temperature programme was a five Bigby, Market Weighton, Bishop Wilton, East Knapton and minutes purge before pyrolysis: 300°C (three minutes) plus Speeton. As with previous investigations, Litosphaeridium 25°C per minute until 650°C was reached. siphoniphorum was not recorded in any of the samples. However, taxa whose last occurrences Marshall and Batten Palynological processing (1988) calibrated approximately to an influx of the latest Cenomanian zonal ammonite Neocardioceras juddii Barrois Five grammes (dark coloured lithologies) or ten grammes and Guerne in NW Germany (Hilbrecht 1986), namely (light coloured lithologies) of crushed, dried material from Adnatosphaeridium tutulosum (in Bed C at Flixton) and samples -1 to -22 were dissolved in hydrochloric acid (35% Carpodinium obliquicostatum (in Bed C at South Ferriby, HCl) and hydrofluoric acid (40% HF) in order to remove and Beds C and E at Flixton), were recorded and illustrated. carbonate and silicate minerals, respectively. Preparations Batten, in Wood et al. (1997), studied two samples from the were sieved with a 10 µm mesh. Kerogen slides were Black Band at Melton Ross (one each from Bed C and Bed E) prepared at this stage. Palynomorphs (illustrated in Figs 5–7), and confirmed an absence of L. siphoniphorum. However, brown and black wood fragments (vitrinite and inertinite analysis of five samples from local Beds II–VI at Site 2 phytoclasts) and clumps of granular amorphous organic revealed the first records of this taxon in the Northern matter (AOM) tend to occur in comparable proportions in the Province, where it is common in occurrence. Dodsworth >10 µm kerogen from the <1% TOC samples at Melton Ross (2000, fig. 12), provided preliminary marker taxa distribution (Table 2; Fig. 8). To improve remaining residues for the data from the samples documented more fully here (Fig. 4), counting of palynomorphs, many of these preparations were corroborating Batten’s record of common L. siphoniphorum cleaned by treatment with a ‘nitric wash’, i.e. one minute of in local Beds I–?III at Melton Ross (Site 1), and indicating the oxidation with nitric acid (70% HNO3), or a rinse with presence of A. tutulosum and C. obliquicostatum higher in the potassium hydroxide solution (2% KOH). In the >10 µm succession (Site 4), from Beds C–F and Bed C, respectively. kerogen fraction from the >1% TOC samples, dark coloured, clumped AOM is dominant (Table 2; Fig. 8). To liberate palynomorphs from the AOM, extended oxidation was given Material and methods with: (1) nitric acid (18–24 hours), followed by one to two Twenty-seven channelled (composite) rock samples (MR97 minutes in an ultrasonic bath with a 2% KOH solution that series) were collected from the top of the Ferriby Chalk was supersaturated with potassium permanganate (KMnO4; Formation and lowermost 1.45 m of the Welton Chalk samples -8, -8.5, -10, -11, -11.5); (2) Schulze’s solution Formation in Melton Ross Quarry by one of us (PD) on 24 (nitric acid supersaturated with potassium chlorate, KClO3), February 1997 and are documented in the present paper. followed by one subsequent rinse with a 2% KOH solution Eleven of our samples (MR97-23 to -14) were collected from (sample -2). The former technique was found to give better Site 1 of Wood and Mortimore (1995). Sites 2 and 3 and the results than the latter in terms of palynomorph preservation lower part of Site 4 of Wood et al. (1997) were submerged and in not selectively destroying gonyaulacoid dinoflagellate below the quarry’s water table in February 1997 and were cysts (cf. Dodsworth 1995, 2004a, fig. 4; Dodsworth and unavailable for sampling. The upper part of Site 4 was Eldrett 2019). All oxidized preparations were stained with accessible and 16 of our samples (MR97-13 to -1) were Safranin O solution (red stain). Full laboratory processing collected from the relatively freshly-exposed, regionally records are available in Supplementary Table A. correlative beds there. The thickness of channelled samples Where palynological recovery permitted, approximately varies from 3 mm to 230 mm, depending on the thickness of equal portions of quantified organic residues from each rock layers (Fig. 4; see the Supplementary Material for sample were strewn over four 22 × 22 mm cover slips, dried Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

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Fig. 5. Dinoflagellate cysts and miospores from Melton Ross. All specimens were photographed at ×400. Sample/slide numbers, specimen England Finder co-ordinates, and BGS specimen registration numbers (MPK prefix) are given. Specimens 1–16 are dinoflagellate cysts; 17–19 are gymnosperm pollen; 20– 21 are angiosperm (Normapolles) pollen. The 50 µm scale bar applies to all specimens. 1. Litosphaeridium siphoniphorum (Cookson and Eisenack, 1958) Davey and Williams, 1966, local Bed I, MR97-22(A), H43/0, MPK 14664; 2. Wrevittia cassidata (Eisenack and Cookson, 1960) Helenes and Lucas-Clark, 1997, local Bed II, MR97-21(A), S43/3, MPK 14665; 3. Carpodinium obliquicostatum Cookson and Hughes, 1964, Bed C, MR97-11.5(B), X47/1, MPK 14666; 4. Adnatosphaeridium tutulosum (Cookson and Eisenack, 1960) Morgan, 1980, local Bed II, MR97-21(B), W31/2, MPK 14667; 5. Cyclonephelium compactum Deflandre and Cookson, 1955 – Cyclonephelium membraniphorum Cookson and Eisenack, 1962, transitional ‘complex’ of Marshall and Batten (1988), Bed C, MR97-11.5(D), Q36/2, MPK 14668; 6. Eurydinium saxoniense Marshall and Batten, 1988, Bed E, MR97-7(B), J42/4, MPK 14669; 7. Pterodinium crassimuratum (Davey and Williams, 1966) Thurow et al., 1988, local Bed I, MR97-22(B), F47/3, MPK 14670; 8. Adnatosphaeridium? chonetum (Cookson and Eisenack, 1962) Davey, 1969, local Bed II, MR97-21(A), S38/3, MPK 14671; 9. Oligosphaeridium totum Brideaux, 1971, Bed C, MR97-11.5(A), F36/0, MPK 14672. This taxon was recorded as Litosphaeridium sp. A by Marshall and Batten (1988), 10. O. totum, Bed C, MR97-11.5 (A), W42/0, MPK 14673; 11. Stephodinium coronatum Deflandre, 1936, Bed E, MR97-8.5(D), V42/2, MPK 14674; 12. Trithyrodinium suspectum (Manum and Cookson, 1964) Davey, 1969, Bed E, MR97-8(A), T35/2, MPK 14675; 13. Palaeohystrichophora infusorioides Deflandre, 1935, local Bed II, MR97-21(A), Q28/4, MPK 14676; 14. Subtilisphaera pontis-mariae (Deflandre, 1936) Lentin and Williams, 1976, Bed C, MR97-11.5(D), R42/1, MPK 14677; 15. S. pontis-mariae, Bed E, MR97-8.5(A), Q25/2, MPK 14678; 16. Sepispinula? huguoniotii (Valensi, 1955) Islam, 1993, Bed C, MR97-10(A), P47/0, MPK 14679; 17. Rugubivesiculites rugosus Pierce, 1961, Bed E, MR97-8(A), R21/1, MPK 14680; 18. Alisporites microsaccus (Couper, 1958) Pocock, 1962, Bed C, MR97-11.5(A), F38/1, MPK 14681; 19. Classopollis spp., Bed G, MR97-2(C), P36/2, MPK 14682; 20. Atlantopollis microreticulatus Krutzsch, 1967, Bed D, MR97-10.5(C), E35/3, MPK 14683; 21. Complexiopollis spp., Bed E, MR97-6(C), N41/4, MPK 14684. Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

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Fig. 6. Dinoflagellate cysts from Melton Ross. All specimens were photographed at ×400. Sample/slide numbers, specimen England Finder co-ordinates, and BGS specimen registration numbers (MPK prefix) are given. The 50 µm scale bar applies to all specimens. 1. Aptea? spongireticulata (Prössl, 1990, ex Prössl, 1992) Fensome et al., 2019, Bed B, MR97-12(D), E32/3, MPK 14685; 2. A.? spongireticulata, Bed D, MR97-9(A), P37/1, MPK 14686; 3. Ginginodinium? sp. A of Prauss (2006, 2012a), Bed D, MR97-10(C), T42/3, MPK 14687. The arrow indicates a probable suture between two precingular plates; 4. Cyclonephelium membraniphorum Cookson and Eisenack, 1962, Bed E, MR97-8.5(C), U28/0, MPK 14688; 5. Heslertonia striata (Eisenack and Cookson, 1960) Norvick, 1976, Bed H, MR97-1(D), U45/0, MPK 14689; 6. Microdinium setosum Sarjeant, 1966, Bed C, MR97-11(D), K47/3, MPK 14690; 7. Ginginodinium? sp. A, Bed E, MR97-8.5(A), Q29/4, MPK 14691. The arrow indicates a probable suture between two precingular plates; 8–9. Canninginopsis? lindseyensis sp. nov., Bed C, MR97-11(B), P44/3, MPK 14663. Holotype. 8. Focus on ventral surface. Note the interpretation of tabulation and sulcal notch (arrow). 9. Same specimen, focus on distal surface; 10. Ellipsodinium rugulosum Clarke and Verdier, 1967, local Bed II, MR97-21(A), N34/2, MPK 14692; 11. Ginginodinium? sp. A, or an endocyst of Trithyrodinium suspectum, Bed H, MR97-1(C), V29/0, MPK 14693; 12. Leptodinium? aff. delicata (this paper), Bed C, MR97-11.5(C), R38/1, MPK 14694. The arrows indicate the possible lateral position of a cingulum; 13. Dinoflagellate? type D of Ioannides (1986), Bed C, MR97-8(B), U29/0, MPK 14695. Note the presence of three or four possible precingular plates and two intercalary or apical plates on the upper part of the cyst; 14. Dinoflagellate? type D, local Bed II, MR97-20(A), S47/4, MPK 14696. Note the presence of at least four ‘plates’ that resemble a precingular series on the upper part of the cyst and further sutures on the lower part of the cyst. and mounted on to microscope slides using Norland Optical counted and multiplied by 44. To give an estimate of Adhesive 61. The proportion of organic residue strewn on ‘absolute abundance’, i.e. the concentration of palyno- each cover slip (e.g. 10% of that derived from a 5 g sample) morphs in each sample (counts per gramme, cpg), the was used to calculate the equivalent mass of original dried mean number of palynomorphs per coverslip was divided rock material represented (e.g. 5 g × 0.10 = 0.50 g repre- by the approximate mass of dried rock material represented sented on the cover slip). on each coverslip. Calculations for each sample are given To obtain an estimate of the number of palynomorphs on in Supplementary Tables B–E. Relative abundances were coverslips, the number in a 1/44 traverse of each was estimated by counting the first three hundred Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

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Fig. 7. Dinoflagellate cysts from Melton Ross. All specimens were photographed at ×400. Sample/slide numbers, specimen England Finder co-ordinates, and BGS specimen registration numbers (MPK prefix) are given. The 50 µm scale bar applies to all specimens. 1. Trithyrodinium? sp. A (this paper), Bed E, MR97-8(C), W29/0, MPK 14697. Note the sub-polygonal/peridinioid shape, laevigate surface and tabulation interpretation, including a prominent suture/ break above the three intercalary plates; 2. Trithyrodinium? sp. A, Bed E, MR97-8(A), R32/2, MPK 14698. Note the sub-polygonal/peridinioid shape, tabular sutures and some probable breakage in the upper-right part of the cyst; 3. Kalyptea spp., Bed C, MR97-11.5(C), V30/0, MPK 14699; 4. ? Dissiliodinium globulus Drugg, 1978, Bed E, MR97-8(C), N39/4, MPK 14700. Polar–dorsal epicystal compression with sutures between some dorsal precingular plates, plus a possible one plate archaeopyle with attached operculum; 5. Bosedinia cf. sp.1 of Prauss 2012b, Bed G, MR97-2(A), M37/4, MPK 14701. Two overlapping specimens. Note the presence of omphali and absence of a kalyptra; 6. Leberidocysta chlamydata (Cookson and Eisenack, 1962) Stover and Evitt, 1978, local Bed II, MR97-21(A), J47/1, MPK 14702; 7. Canninginopsis? lindseyensis sp. nov., Bed C, MR97-11(B), W33/2, MPK 14703. Note the interpretation of precingular tabulation and sulcal notch (arrow); 8. ?D. globulus, Bed E, MR97-8(B), G27/2, MPK 14704. There are two precingular plates with sutures on the specimen and an archaeopyle involving some detached dorsal precingular plates; 9. Bosedinia cf. sp.1 of Prauss 2012b, Bed E, MR97-8.5(A), U39/4, MPK 14705. Note the operculum, probably including apical and three intercalary plates; 10. Bosedinia cf. sp.1 of Prauss 2012b, or an endocyst of Subtilisphaera spp., Bed G, MR97-2(C), O39/4, MPK 14706; 11. Bosedinia laevigata (Jiabo, 1978, ex He and Qian, 1979) He, 1984, Bed E, MR97-8(A), R31/0, MPK 14707; 12. B. laevigata, Bed C, MR97-11(E), H57/3, MPK 14708. Note the operculum, including apical and probable intercalary 2a and 3a plates (indicated); 13. B. laevigata, Bed C, MR97-11.5(A), W40/1, MPK 14709; 14. Trithyrodinium maculatum sp. nov., Bed C, MR97-11.5(A), E45/0, MPK 14710. Endocyst. Note the three anterior intercalary plates archaeopyle with at least two attached operculum plates, and the endocyst wall marked by ring-shaped indentations; 15. T. maculatum, Bed C, MR97-10(A), B49/2, MPK 14711. Endocyst. Focus on probable intercalary plates at top of specimen; 16. Fromea amphora Cookson and Eisenack, 1958, Bed C, MR97-11.5(A), N32/1, MPK 14712; 17. B. laevigata, Bed C, MR97-11.5(A), J43/3, MPK 14713; 18. T. maculatum, Bed F, MR97-3(A), S32/3, MPK 14662. Holotype. Note comparable ring-shaped indentations on endophragm and periphragm. The likely position of the three intercalary plate archaeopyle (operculum plates detached) is indicated; 19. T. maculatum, Bed B, MR97-12(D), K29/2, MPK 14714. Endocyst. Note the two plate intercalary archaeopyle (2a [isodeltaform hexa-type] and 3a plates detached); 20. Sentusidinium ringnesiorum (Manum and Cookson, 1964) Wood et al., 2016, Bed C, MR97-11.5(A), K42/2, MPK 14715; 21. B. laevigata, Bed E, MR97- 8(B), X34/0, MPK 14716. Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

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Table 2. Summary of palynomorph concentration (counts per gramme), total organic carbon (TOC), palynomorph groups (gymnosperm pollen; pteridophyte/bryophyte spores; angiosperm pollen; dinoflagellate cysts; prasinophyte phycomata; acanthomorph acritarchs), separate >10 µm kerogen counts of 100 particles (AOM = amorphous organic matter; phytoclasts; palynomorphs) and dinoflagellate cyst species richness (‘diversity’). Shaded rows highlight samples with >1 wt% TOC. T/M ratio = terrestrial/marine ratio. P/G ratio = the ratio between peridinioid (P) and gonyaulacoid (G) dinoflagellate cysts

palynomorphs identified (0.3% = 1 specimen; 0.7% = 2 70778 and MPA 71640 to 71642; type and figured specimen specimens; 1% = 3 specimens, etc.). The remainder of the numbers MPK 14662 to 14716). For the relationship first coverslip and, where applicable, the three additional between MPA numbers and the original sample numbers coverslips, were subsequently scanned for additional rare used in this paper, see Supplementary Table F. A full range taxa. Relative abundances are described as ‘rare’ (outside chart of palynological data is available in the Supplementary the count), ‘frequent’ (0.3–0.7%), ‘common’ (1–9.7%) or Material. Full author names and synonyms of dinoflagellate ‘abundant’ (10% +). Separate counts of 100 kerogen cysts, prasinophyte phycomata and acritarchs can be found in particles (AOM, phytoclasts and palynomorphs) were Fensome et al. (2019). made from the unoxidized kerogen slides. Further samples from Caistor, Bigby, South Ferriby, Market Stable isotopes Weighton, Bishop Wilton, East Knapton, Flixton and Speeton were processed and analysed for palynology only, All samples were analysed for stable carbon and oxygen using the methods described above, with preliminary isotopes on carbonates (Supplementary Table G). Analyses summary results presented herein. were undertaken in the laboratory of the Department of Earth Standard palaeoenvironmental parameters have been Sciences, Oxford University, UK. Oxygen and carbon calculated for the Melton Ross section, including: (i) the isotope analytical methods were adapted from those ratio between terrestrial (T) and marine (M) palynomorphs described in Day and Henderson (2011, section 2.7). All (T/M ratio) as a proxy for terrestrial input, (ii) the ratio oxygen isotope measurements were performed on a Delta V between peridinioid and gonyaulacoid dinoflagellate cysts Advantage isotope mass spectrometer fitted with a Gas (P-cysts and G-cysts, the P/G ratio) as a proxy of nutrient Bench II. The Gas Bench II device converted the carbonates input and (iii) the species richness, i.e. the number of to carbon dioxide (CO2) with 100% phosphoric acid (H3PO4) dinoflagellate cyst taxa recorded as a proxy of their diversity. at 72°C (McCrea 1950). The relative 18O/16O values (δ18O) Our detailed discussion of palaeoenvironmental parameters of carbonate are expressed in per mil (‰) relative to Vienna is provided in Eldrett et al. (2017); see also McLachlan et al. Pee Dee Belemnite (VPDB) on a normalized scale such that (2018) for a recent review of the P/G ratio. the δ18O of NBS-19 is -2.2‰ and the δ18O of NBS-18 is All Melton Ross palynological slides are curated in the -23.01‰. The relative 13C/12C values (δ13C) of carbonate are MPA and MPK collections of the British Geological Survey, expressed in per mil relative to VPDB on a normalized scale Keyworth, Nottingham, UK (slide numbers MPA 70686 to such that the δ13C of NBS-19 is 1.95‰ and the δ13C of NBS- Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

100 P. Dodsworth et al.

Fig. 8. Kerogen (>10 µm fraction) photographs from Melton Ross. All fields of view are at 200 × 200 µm. Photographs 2, 11 and 12 are from stained kerogen slides. 1. Bed G, MR97-2(K), O42. Note the dominance of amorphous organic matter (AOM); 2. Bed F, MR97-4(A), N42. Note the dominance of dinoflagellate cysts (d.c.) and small phytoclasts; 3. Bed F, MR97-5(K), N42. Note the presence of translucent (brown) phytoclasts and AOM; 4. Bed E, MR97-8(K), O42. Note the dominance of AOM; 5. Bed E, MR97-8.5(K), O42; 6. Bed D, MR97-9(K), O42. Note the prominence of dinoflagellate cysts, including Spiniferites ramosus (S.r.); 7. Bed C, MR97-11(K), O42. Note the dominance of AOM; 8. Bed C, MR97-11.5(K), N42; 9. Bed B, MR97-12(A), O43. Note the dinoflagellate cysts, including Oligosphaeridium totum (O.t.), phytoclasts and pyritic mineral material; 10. Local Bed VII, MR97-15(A), O43; 11. Local Bed II, MR97-21(A), O42. Note dinoflagellate cysts, including Palaeohystrichophora infusorioides (P.i.), Subtilisphaera spp. (Subt.) and Leberidocysta chlamydata (L.c.); 12. Local Bed I, MR97-22(A), O41. Note the dinoflagellate cysts, including Litosphaeridium siphoniphorum (L.s.).

18 is -5.01‰. External error (0.07 and 0.09 for δ13C and Results δ18O, respectively) is calculated from repeat measurements Organic geochemistry of Oxford University’s in-house standard NOCZ. It is assumed that the phosphoric acid–carbonate fractionation is The two chalk samples (top Ferriby Chalk Formation, the same for NBS-19 and Oxford University’s calcite sample -23, 0.04% TOC; Central Limestone, sample -14, samples (Coplen 1996). For carbonates and waters, results 0.10% TOC) contain the lowest organic carbon values in the are expressed on the same normalized scale such that δ18Oof sampled section. The ‘anomalous’ lower succession marls SLAP2 reference water is -55.5‰. (local Beds I–VII; samples -22 to -15) range from 0.11% to Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

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Fig. 9. Van Krevelen-type diagram for the Melton Ross samples analysed for Rock-Eval pyrolysis. Blue-filled circles are data for the >1 wt% TOC samples.

Open circles are data for the <1 wt% TOC samples; the latter are unreliable, due to probable elevation by occluded CO2 within carbonate of inorganic origin, in addition to that derived from early diagenesis of organic matter.

0.16% TOC, with the exception of the darker coloured marl hydrogen index (HI) in the dark grey marl samples ranges layer (local Bed II, sample -21), which has 0.28% TOC. In from 78 (sample -11) to 203 mg HC/g TOC (sample -2) the ‘standard’ upper succession, the lighter coloured while the oxygen index (OI) ranges from 15 (sample -11.5) to lithologies of Bed B (sample -13, 0.12% TOC; sample -12, 26 mg CO2/g TOC (sample -8) in the same samples 0.20% TOC), Bed D (sample -9, 0.36% TOC) and Bed F (Supplementary Table H). On a modified Van Krevelen (samples -3 to -5, 0.12% to 0.34% TOC) contain the lowest diagram (Fig. 9), these samples plot within the Type III values while the dark grey marl samples contain the highest organic matter (mainly terrestrially derived) field, with values: Bed C (samples -11.5, -11 and -10, 1.43% to 2.2% samples -11.5 and -2 plotting towards Type III–II organic TOC), Bed E (samples -8.5 and -8, 2.74% and 2.18% TOC, matter (mixed terrigenous and marine type). The lighter respectively) and Bed G (sample -2, 3.47% TOC). The coloured lithologies between the dark grey marls give HI Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

102 P. Dodsworth et al.

Table 3. Relative and absolute abundance of selected gonyaulacoid dinoflagellate cysts (G-cysts) and Dinoflagellate? type D of Ioannides (1986).P= present, not quantified (rare occurrence, outside the 300 palynomorph count). The calculation of absolute abundance per gramme of sample (cpg) is explained in the text

values of 40 to 78 mg HC/g TOC and relatively high OI high concentrations of palynomorphs, 85 184 to 219 648 cpg values (27 to 165 mg CO2/g TOC), as does sample -22 from in samples -11.5, -11, -10, 8.5, -8 and -2, i.e. in the same local Bed II (HI = 39, OI = 53; Supplementary Table H). samples that have the highest TOC values of 1.43–3.47%. However, with regard to characterizing organic matter type, The lighter coloured lithologies between the dark grey marls the OI data may be unreliable in these low TOC, carbonate- show a broad correlation between palynomorph concentra- rich samples, due to probable elevation by occluded CO2 tion and TOC, 17 204 to 53 284 cpg within the Black Band within carbonate of inorganic origin, in addition to that (samples -10.5, -9, -7, -6), where concentration is still derived from early diagenesis of organic matter (P. Barnard exceptionally high, and 1470 to 8668 cpg in Bed F. The pers. comm. 2019). assemblage in Bed H is comparable to that in Bed G and is interpreted to be mainly derived from reworked clasts of the latter (see Supplementary Material), given that Bed H is Palynology palynologically barren at four other localities where it has In the lower succession, local Bed I (sample -22) and Bed ?III been sampled (Louth, Bigby, Caistor and South Ferriby; Hart (sample -20), respectively, yielded an estimated 53 and 95 et al. 1993; Supplementary Table I). palynomorph counts per gramme (cpg) while Bed II (sample The dinoflagellate cyst assemblage from local Bed II -21) has a much higher concentration of palynomorphs, 12 408 (sample -21) is diversified with 77 taxa present (Table 2). cpg (Table 2). Beds ?IV to VII (samples -19 to -17) yielded The adjacent samples (-22 and -20) from local Beds I and ? between 5 and 88 cpg, dominated by one taxon, Dinoflagellate? III, along with the samples from Bed B (-12 and -13) contain type D of Ioannides (1986) (Table 3; Figs 6.13, 6.14). The fewer taxa (32–33) but this may mainly reflect a much topmost part of the lower succession (samples -15 and -16) and smaller number of specimens inspected from these lower overlying Central Limestone (sample -14) are palynologically recovery samples. Relatively high diversity dinoflagellate barren or contain up to two dinoflagellate cysts. cyst assemblages are noted from the darker lithologies of the Palynological recovery and preservation from the upper Black Band (68–79 taxa) with slightly fewer taxa in the succession in the freshly excavated Site 4 samples is better lighter coloured inter-beds (Bed C, sample -10.5, and Bed D; overall than that from many samples in other quarries 65 and 63 taxa, respectively) and overlying Bed F (53–69 investigated to date (Supplementary Table I). Recovery from taxa). Bed G yielded 62 taxa, fewer than from comparable Bed B is sparse in sample -13 (28 cpg) and slightly richer in dark lithologies in the Black Band. sample -12 (288 cpg). The dark grey marl samples of the The lower succession has the highest P/G ratio in the Black Band (Beds C to E) and Bed G contain exceptionally sampled section (average 0.61), with P-cyst taxa Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

Melton Ross palynology and geochemistry 103

Table 4. Relative and absolute abundance of common/abundant peridinioid dinoflagellate cysts (P-cysts). P = present, not quantified (rare occurrence, outside the 300 palynomorph count). The calculation of absolute abundance per gramme of sample (cpg) is explained in the text

Palaeohystrichophora infusorioides (Fig. 5.13) and sample -3 from Bed F (Table 3). Litosphaeridium siphoni- Subtilisphaera pontis-mariae (Figs 5.14, 5.15), respectively phorum (Figs 5.1, 8.12) is restricted to the lower succession, comprising an average 19.4% and 23.0% of total palyno- where it is common (1–2.7%). Cyclonephelium compactum– logical assemblages from samples -22 to -20 (Table 4). In the membraniphorum (Figs 5.5, 6.4) is rare in the lower upper succession, P-cysts are subordinate to G-cysts in all succession but is consistently abundant throughout the samples, though they occur in higher relative and absolute upper succession, from basal Bed B to Bed H (average abundances in the more organic-rich (>1% TOC), dark grey 21.5%). An isolated specimen of Oligosphaeridium totum marl samples (average P/G ratio of 0.33) than the lighter (Figs 5.9, 5.10, 8.9) was recorded from sample -17 but the coloured lithologies of Beds B–D (average P/G ratio, 0.04) taxon is only consistently recorded from Bed B to Bed F and and upper Bed E to Bed F (average P/G ratio, 0.26; Table 2). has an acme in upper Bed B (40.3%; Table 3). Sepispinula? Trithyrodinium suspectum (Fig. 5.12) and Ginginodinium? huguoniotii (Fig. 5.16) is common to abundant from Bed B sp. A of Prauss (2006, 2012a)(Figs 6.3, 6.7) occur in most of to lower Bed E (samples -13 to -8.5). the productive samples from both lower and upper succes- There is a relative increase in prasinophyte phycomata, sions, respectively comprising 0.3–7% and 0.3–1.7% of total mainly the genera Leiosphaeridia, Pterospermella and palynological assemblages. Palaeohystrichophora infusor- Tasmanites, in the darker intervals at Melton Ross (0.7–1% ioides and S. pontis-mariae also occur consistently in the in Bed C; 1.3–6% in Bed E; 6.3% in Bed G). Acanthomorph upper succession. With the exception of sample -6, the acritarchs are also present in higher percentages in the darker former is relatively rare (1–5%) in the Black Band and more >1% TOC lithologies (average 3.9% of the total palyno- common (7.7–11.3%) in Bed F while the latter is more logical assemblage) than in the <1% TOC samples (average common in the >1% TOC samples of the Black Band (10.7– 0.6%). They are mainly represented by Veryhachium spp., 18.7%). Bosedinia cf. sp. 1 of Prauss (2012b) (Figs 7.5, 7.9, apart from Bed G (sample -2), in which Micrhystridium is 7.10) is also relatively common in the >1% TOC samples prominent (11%; Table 2). (1.3–6%). Eurydinium saxoniense (Fig. 5.6) occurs consist- Terrigenous palynomorphs are present in higher relative ently in Beds C and D, with its first confirmed occurrence in and absolute abundances in the more organic-rich (>1% sample -11.5 at the base of the former, and is relatively TOC) samples (average T/M ratio of 0.103 and concentration common (1.7–8%) in Beds E, F and G (Table 4). of 12 555 cpg) than in adjacent lithologies with lower (<1%) The G-cyst taxon Spiniferites spp. is prominent in most TOC values (Table 2; average T/M ratio, 0.023; average productive samples throughout the section, 5.4–28.3% of concentration, 524 cpg; Supplementary Table E). total palynological assemblages, while Pterodinium spp. Terrigenous palynomorphs are mainly composed of gymno- comprises 1–5% of assemblages, with an acme (10%) in sperm taxa (4.7–13.7% of total palynological assemblages Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

104 P. Dodsworth et al. from >1% TOC samples), predominantly bisaccate pollen, foraminifera in the dark coloured mudstones (Hart and Bigg including Rugubivesiculites rugosus (Fig. 5.17) and 1981; Hart et al. 1993; Dodsworth 1996, fig. 6). The Alisporites microsaccus (Fig. 5.18), along with subordinate assemblage in the mudstones adjacent to the Black Band is Classopollis spp. (Fig. 5.19) and Inaperturopollenites comparable to those of the upper part of the Plenus Marls in hiatus. Pteridophyte spores, including Deltoidospora spp. southern England (Beds 4–8). This led Hart and Bigg (1981) and Gleicheniidites spp. are persistent and rare to common to suggest that the Black Band may be the lateral equivalent but do not exceed 3% of the total palynological assemblages. of Bed 6, a relatively clay-rich unit. On grounds of event Normapolles angiosperm pollen, Atlantopollis microreticu- stratigraphy, i.e. the most argillaceous levels within the CTB latus (Fig. 5.20) and Complexiopollis spp. (Fig. 5.21) occur successions of the Northern and Southern Provinces, Jeans in most productive samples but are rare and compose less et al. (1991) also suggested a correlation of eastern England than 1% of the palynological assemblages. With the probable Black Band, Beds C and E, with southern England Beds 4 exception of an occurrence of the dinoflagellate cyst and 6, respectively. However, a correlation of the Black Band Sindridinium borealis in sample -11 (reported Albian– with a level in the Plenus Marls is not supported by the Early Cenomanian stratigraphic range; Nøhr-Hansen et al. palynological and stable isotopes data presented in this study 2018), palynomorphs reworked from older formations were (see below). not recorded in the Melton Ross section. Hart and Bigg (1981) found the first occurrence (FO) of Helvetoglobotruncana praehelvetica (Trujillo) in Bed H at Stable isotopes Elsham. This taxon is an early morphotype of Helvetoglobotruncana helvetica (Bolli), the diagnostic The sample (-23) from the top of the Ferriby Chalk zonal marker for the Early to Middle Turonian in Tethyan δ13 ‰ Formation yielded a C value of 2.49 . In the lower areas. The FO of H. helvetica was tentatively recorded from a ‘ ’ δ13 ‰ succession, there are three peaks in the C data above 3 marl seam at South Ferriby (Hart and Leary 1989)that (samples -22 to -21, -19, and -17 to -15), separated by two probably correlates with the marl seam above the Turnus Bed ‘ ’ ‰ troughs below 3 (samples -20, -18 to -18.5). Maximum at Melton Ross (Fig. 4). However, its FO is based on the values for the section are from the Central Limestone (Bed A, (highly subjective) evolutionary boundary between praehel- ‰ ‰ sample -14, 4.25 ) and Bed B (sample -13, 4.21 ; sample vetica and helvetica (Hart and Leary 1989). The rarity of H. ‰ -12, 4.17 ). Values show an overall decline through the helvetica at high latitudes such as Lincolnshire also renders ‰ ‰ Black Band, from 3.91 (sample -11.5) to 3.52 (sample its FO impracticable as a confident time-diagnostic event in ‰ -6). Above a trough in Bed F (3.34 in sample -4), there is a the Northern Province (Hart 2019). In NW Germany, ‰ subsequent peak in Bed G (3.77 in sample -2). The highest Hilbrecht (1986) reported the FO of H. helvetica within the ‰ sample analysed (-1) from Bed H yielded a value of 3.14 Fish Shale. At Dover, southern England, its FO is difficult to (Supplementary Table G). locate precisely in the nodular chalk lithology of the Ballard δ18 − − ‰ The O data fluctuate in the 3.58 to 5.12 range in Cliff Member (above the Plenus Marls), as this is difficult to the lower succession. Minimum negative values for the process for calcareous microfossils (Hart and Leary 1989). − ‰ section occur in the Central Limestone ( 3.03 in sample At Eastbourne, the FO of H. helvetica is picked between − ‰ -14; Fig. 4) and overlying basal Bed B ( 3.25 in sample - Mead Marls 3 and 4 of the Ballard Cliff Member (Jarvis et al. δ18 13). Upper Bed B and Beds C to H, all yielded O values 2006). In Figure 4, the planktonic foraminiferal zonation is − ‰ more negative than 4.5 , with three notable peaks in the extrapolated to Melton Ross from Elsham and South Ferriby. samples with >1% TOC (lower Bed C, lower Bed E and Bed G; −5.35‰ to −6.46‰). Palynology Stratigraphy Several dinoflagellate cysts have widespread range bases and tops in the Cenomanian and Turonian stages, and have been Micropalaeontology used to zone their substages (Clarke and Verdier 1967; A study of foraminifera at Melton Ross has not yet been Burgess 1971; Foucher 1981; Williams 1977; Williams et al. undertaken. The Cenomanian planktonic marker taxon 2004). Regional zonations have recently been revised for Rotalipora cushmani (Morrow) has been recorded from the Central and Northern Europe (Olde et al. 2015a) and adapted Ferriby Chalk Formation in eastern England, at South Ferriby for the Western Interior of the USA (Dodsworth and Eldrett and Elsham, but has to date not been recorded from above the 2019). erosion surface at the base of the Welton Chalk Formation The LO of consistent and common Litosphaeridium (Hart et al. 1993). In most southern England sections, it siphoniphorum in the lower succession at Melton Ross ranges up into the lower part of the Plenus Marls, e.g. Bed 3 (sample -20) correlates with its LO in the pre-Plenus at Dover (Jarvis et al. 1988a) and Bed 4 at Eastbourne (Jarvis sequence of NW Germany, at Wunstorf outcrop (Marshall et al. 2006). At Misburg, R. cushmani occurs in Cenomanian and Batten 1988) and core (van Helmond et al. 2015) and strata and has its last occurrence (LO) in the pre-Plenus ‘black Misburg outcrop (Marshall and Batten 1988). In southern shale’ succession (Hilbrecht 1986). Future inspection of our England, the LO of common L. siphoniphorum occurs in samples from Melton Ross will test for its presence in Plenus Marls Bed 6 at Lulworth and Eastbourne (Fig. 1; localized Beds I–VII. Dodsworth 2000; Pearce et al. 2009) while isolated speci- The regionally correlative Beds B–H in eastern England mens have been recorded from Bed 7 and Bed 8 at Lulworth are dominated by a Hedbergella/Whiteinella assemblage, (Dodsworth 2000). Isolated specimens have also been with an increase in small buliminids and simple agglutinated sporadically recorded from Turonian and Coniacian deposits Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

Melton Ross palynology and geochemistry 105 at some localities in southern England, France, NW Germany Germany, Marshall and Batten (1988) only recorded O. (Clarke and Verdier 1967; Foucher 1982, 1983; Marshall and totum from above the Plenus Bed at Wunstorf (their sample Batten 1988) and Pueblo, Colorado (Dodsworth 2000). 38) and at Misburg (their samples 27, 22 and 20). At These isolated Turonian and younger occurrences are Misburg, an influx of O. totum was indicated, with its base in probably reworked specimens. Previous reports of the LO sample 22, collected from a bed that contains the only of consistent L. siphoniphorum in Lower Turonian deposits occurrence of the latest Cenomanian zonal ammonite (Williams and Bujak 1985; Costa and Davey 1992) probably Neocardioceras juddii in the section. An acme of O. totum derive from former assignment of the Plenus Marls in occurs in overlying sample 20. In central Poland, O. totum southern England to this substage (e.g. Jefferies 1962, 1963); occurs in sample Pul-17 of the Pulawy borehole (Fig. 1), the Plenus Marls have subsequently been confidently within the δ13C excursion that spans the CTB (Peryt and reassigned to a Late Cenomanian age (e.g. Jarvis et al. Wyrwicka 1993), one sample above the FO of abundant C. 1988a; Gale et al. 1993). A Late Cenomanian LO of compactum–membraniphorum (sample Pul-16). This, in consistent L. siphoniphorum has been reported worldwide, turn, is stratigraphically higher than the LO of consistent/ including other locations in southern England (Davey 1969; common L. siphoniphorum (sample Pul-15). Thus, the three Hart et al. 1987; Jarvis et al. 1988b), the Witch Ground bio-events also occur in the same relative order over a Graben, Central North Sea (Harker et al. 1987), France condensed (<1 m thick) interval in that section (Dodsworth (Foucher 1979, 1980; Courtinat et al. 1991), northern Spain 2004b). (Mao and Lamolda 1999), Crimea (Dodsworth 2004a), The LO of Adnatosphaeridium tutulosum (Fig. 5.4) occurs Poland (Dodsworth 2004b), eastern USA (Aurisano 1989), in Bed F at Melton Ross (sample -5). It was recorded from Bed the Western Interior of the USA (Courtinat 1993; Dodsworth C at Flixton (Dodsworth 1996). At other European and North 2000, 2016; Eldrett et al. 2015a; Dodsworth and Eldrett America locations, the LO of A. tutulosum also occurs within 2019), Ocean Drilling Project holes including Demerara Rise the uppermost Cenomanian, above the LO of consistent/ (Fig. 1; Leg 207, Site 1260) and Kerguelen Plateau (Leg 183, common L. siphoniphorum and the FO of abundant C. Site 1138; Eldrett et al. 2017), Australia (Morgan 1980; compactum–membraniphorum: in NW Germany, above the McMinn 1988) and New Zealand (Hasegawa et al. 2013; Plenus Bed at Wunstorf and Misburg outcrops (Marshall and Schiøler and Crampton 2014). Batten 1988); in southern England, at Hooken Cliffs, Devon At Melton Ross, the LO of Pterodinium crassimuratum (Jarvis et al. 1988b), Eastbourne (Plenus Marls Bed 8; Pearce (Fig. 5.7) occurs in sample -21, close to the LO of consistent/ et al. 2009) and 0.5 m above the Plenus Marls at Lulworth common L. siphoniphorum in sample -20. Davey and (Dodsworth 2000); and in southern France (cf. Courtinat et al. Williams (1966) and Clarke and Verdier (1967) recorded it 1991; Jarvis et al. 2011) and the Western Interior of the USA from beds of Middle and Late Cenomanian age in southern (Dodsworth 2000; Harris and Tocher 2003; Dodsworth and England, its LO coinciding with that of L. siphoniphorum Eldrett 2019). The LO of A. tutulosum is at the same level as within the Plenus Marls on the Isle of Wight and at a slightly the LO of L. siphoniphorum in northern France (Foucher higher level at Eastbourne, in Plenus Marls Bed 8 (Pearce 1983) and Crimea (Dodsworth 2004a). et al. 2009). At Pueblo, Colorado, the LO of P. crassimur- The LO of Carpodinium obliquicostatum (Fig. 5.3) occurs atum also occurs in the Upper Cenomanian (Dodsworth and in Bed C (sample -11.5) at Melton Ross. It was recorded from Eldrett 2019). Bed E at South Ferriby and Flixton (Dodsworth 1996). In The FO of abundant Cyclonephelium compactum–mem- NW Germany, Marshall and Batten (1988) reported it above braniphorum in lower Bed B (sample -13), immediately the Plenus Bed in the Wunstorf and Misburg outcrops. In above the Central Limestone at Melton Ross, correlates with southern England, it occurs 0.5 m above the Plenus Marls at the base of its abundant occurrence immediately above the Lulworth (Dodsworth 2000). Although rare and sporadic in Plenus Bed in NW Germany, at Wunstorf outcrop (Marshall occurrence, its range top in the Western Interior is reported to and Batten 1988) and core (van Helmond et al. 2015), and coincide approximately with that of A. tutulosum at Pueblo, Misburg outcrop (Marshall and Batten 1988). The event is Colorado (Dodsworth 2000). less clearly defined in southern England, but can be Microdinium setosum (Fig. 6.6) occurs fairly consistently tentatively picked near the top of the Plenus Marls, in Bed in the Black Band at Melton Ross, with its LO in Bed E 7 at Eastbourne (Pearce et al. 2009) and Bed 8 at Lulworth (sample -6). In southern England, it occurs throughout the (Dodsworth 2000). Cyclonephelium membraniphorum is Cenomanian (Clarke and Verdier 1967) and is sporadic in the rare or absent in coeval Tethyan sections farther south, in Plenus Marls with an LO in Bed 2 at Eastbourne (Jarvis et al. Spain (Lamolda and Mao 1999; Peyrot 2011; Peyrot et al. 2011) and Bed 7 at Lulworth (Dodsworth 2000). However, it 2011, 2012) and Morocco (Prauss 2012a, b). occurs sporadically as high as Middle Turonian in the North At Melton Ross, an influx of Oligosphaeridium totum Sea Basin (Costa and Davey 1992). from Bed B to lower Bed C can be correlated with an influx At Melton Ross, Adnatosphaeridium? chonetum (Fig. 5.8) of O. totum from the same levels at Caistor (samples CL-11 was recorded from local Bed II (sample -21), with an to CL-9; 1–3%) and from upper Bed B at Market Weighton isolated, questionable specimen also present in Bed E (samples MW-20 to MW-18; 3–6%; see Supplementary (sample -6). It has previously been recorded from Bed C at Table I for sample positions). Duane (in Hart et al. 1993) Flixton (Dodsworth 1996). The occurrence of A.? chonetum recorded its highest relative abundance (3.4%) in the lower in Cenomanian deposits was noted by Davey (1969) in part of the Black Band (their sample SFE-18) at South Northern Europe and by Cookson and Eisenack (1962) and Ferriby (the underlying Bed B samples SFE-19 and SFE-20 Backhouse (2006) in Australia. In the Western Interior of the at South Ferriby were palynologically barren). In NW USA, it is common in the Upper Cenomanian Substage, with Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

106 P. Dodsworth et al. an uppermost Cenomanian LO (Harris and Tocher 2003; Cyclonephelium membraniphorum Zone of these authors, Dodsworth and Eldrett 2019). In the Shetland Group, with Bed B to lowermost Bed F belonging to the offshore Norway, it reappears in Coniacian and Lower Adnatosphaeridium tutulosum Subzone of Dodsworth and Santonian deposits (PD, personal observation). Eldrett (2019; Fig. 4). The FOs of Canningia glomerata, Heterosphaeridium At Wunstorf, Prauss (2006) reported acanthomorph difficile, Florentinia buspina, F.? torulosa and acritarchs. Higher relative abundances of Veryhachium Senoniasphaera turonica are intra-Lower Turonian biostrati- (c. 1–2%) occur in darker lithologies from the pre-Plenus graphic marker events in Europe (Davey and Verdier 1976; and lower post-Plenus succession, relative to lighter coloured Foucher 1980, 1981, 1983; Tocher and Jarvis 1987; Jarvis inter-beds. There is a large influx of Micrhystridium in the et al. 1988a; Costa and Davey 1992; FitzPatrick 1995; Pearce upper part of the Fish Shale (c. 15–70%). Following Wall et al. 2003, 2009, 2011). These taxa have not been recorded (1965) and Downie et al. (1971), Prauss (2006) attributed the at Melton Ross or in any of the other eastern England Veryhachium occurrences to a distal offshore, hydrodyna- localities/samples indicated in Supplementary Table I. Thus, mically quiet environment, and the prominent acritarch peak Beds C–G are probably stratigraphically lower than their dominated by Micrhystridium within the upper part of the range bases. Fish Shale to the influence of a relatively near-shore In terms of dinoflagellate cyst zonation, the palynologi- turbulent water environment. An up-section change from cally productive samples from the lower succession at common Veryhachium (Beds C to E) to abundant Melton Ross are assigned to the Litosphaeridium siphoni- Micrhystridium (Bed G) at Melton Ross may correlate with phorum Interval Zone of Olde et al. (2015a) and Dodsworth that reported from Wunstorf. and Eldrett (2019). The productive part of the upper The consistent presence of the bisaccate pollen succession (Bed B to Bed G) is assigned to the Rugubivesiculites rugosus in the upper succession at

Fig. 10. Lithological succession in the Bridge Creek Limestone Member of the Greenhorn Formation, on the north side of the Pueblo Reservoir State Recreation area, west of Pueblo, Colorado, USA. This section contains the Global boundary Stratotype Section and Point (GSSP) for the base of the Turonian Stage (38° 16′ 56′′ N, 104° 43 ′ 39′′ W) and the proposed GSSP for the base of the Middle Turonian Substage (Bengtson et al. 1996; Kennedy et al. 2000, 2005; Dodsworth and Eldrett 2019). (a) Metres above/depth below the base of Bridge Creek Member; (b) chronostratigraphy; (c) lithostratigraphy; (d) lithology; (e) δ13Corg, data from Bowman and Bralower (2005). Peaks ‘a’, ‘b’ and ‘c’ in the OAE-2 excursion follow Jarvis et al. (2006); (f) summary of proposed regional correlation with sections from NW Europe (this paper); (g) Pueblo ammonite zones after Kennedy and Cobban (1991); Cobban (1993) and Kennedy et al. (2000). The Watinoceras devonense, Pseudaspidoceras flexuosum and Vascoceras birchbyi units are often treated as subzones of a Watinoceras coloradoense Zone or Watinoceras spp. Zone in published literature; (h) Pueblo inoceramid bivalve zonation by Walaszczyk and Cobban in Kennedy et al. (2000); (i) Pueblo planktonic foraminiferal zones are from Caron et al. (2005) and Keller and Pardo (2004);(j) subzones are from Keller and Pardo (2004). There is a difference between Keller and Pardo (2004) and Caron et al. (2005) on the base of Helvetoglobotruncana helvetica. This difference is marked by the vertical line in the figure; (k) nannofossil zones are from Bralower (1988) and Bralower and Bergen (1998); (l), (m) dinoflagellate cyst zones and subzones are from Dodsworth and Eldrett (2019). This diagram is adapted from Dodsworth and Eldrett (2019). The main sources for NW Europe correlation are: Melton Ross, Wood and Mortimore 1995; Wood et al. 1997, this paper, C.L. = Central Limestone; Misburg HPCF II quarry, Hilbrecht 1986; Hilbrecht and Hoefs 1986; Prauss 2006, P.P. = pre-Plenus succession, P.B. = Plenus Bed, triple = ‘triple band’; Eastbourne, Jarvis et al. 2006; Pearce et al. 2009, Beds 1–8 compose the Plenus Marls, the overlying Mead Marls occur within the Ballard Cliff Member and the Holywell Marls occur within the Holywell Member. Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

Melton Ross palynology and geochemistry 107

Melton Ross is noteworthy. It has recently been reported throughout the Upper Cenomanian–Middle Turonian section exposed at Pueblo, Colorado (Dodsworth and Eldrett 2019) and in Turonian cores from Texas (e.g. Iona-1; Eldrett et al. 2017). In the Greenland area, Nøhr-Hansen (2012, appendix 1), Fensome et al. (2016) and Nøhr-Hansen et al. (2016) indicated that Rugubivesiculites spp./R. rugosus has a consistent LO within the Turonian.

Calcareous nannofossils A study of calcareous nannofossils at Melton Ross has not yet been undertaken, but Bralower (1988) reported their ranges from the CTB interval at other quarries, including the nearby sections at South Ferriby and Elsham (Fig. 2). The Fig. 11. Scatter diagram plotting δ13C-δ18O co-variance for the Melton LOs of the coccoliths Axopodorhabdus albianus (Black), Ross section to help elucidate the primary v. diagenetic signals. Black Helenea chiastia Worsley and Rhagodiscus asper Stradner circles = > 0.2 wt% TOC; white circles = < 0.2 wt% TOC. Reference fields occur in Bed H at South Ferriby. At Elsham, the LO of R. plotted from Moore (1989), with fields of well-preserved foraminifera (after Veizer and Prokoph 2015; O’Brien et al. 2017) most likely asper also occurs in Bed H but the LOs of H. chiastia and A. reflecting unaltered δ13C-δ18O values indicative of primary Late albianus occur, respectively, 20 cm and 15 cm lower, within Cretaceous seawater. Field of bulk rock δ13C-δ18O values from CTB undifferentiated variegated marls. At Misburg, NW sections after Jarvis et al. (2011, 2015). Regression lines and R2 values Germany, all three events occur within Lower Turonian plotted for all samples (black line) and low TOC samples between deposits above the Fish Shale (cf. Bralower 1988, fig. 21, and samples MR97-11 and MR97-23 (dashed line). Hilbrecht and Hoefs 1986, fig. 2), with the LOs of H. chiastia and A. albianus in a ‘triple band’ of stratigraphically higher, Beds I–VII and Beds A and B that contain low TOC (<0.2%) dark coloured mudstones, and the LO of R. asper c. 5m do show a relatively strong co-variance (R2 = 0.84), indicat- above the ‘triple band’. At Dover, southern England, the ing potential dissolution and re-precipitation of isotopically three events occur stratigraphically lower, within Upper light 13C cements through interaction with meteoric pore Cenomanian deposits, i.e. the highest 0.55 m of the Plenus fluids during burial in this interval. Conversely, the δ13C and Marls that is 4.45 m thick at the sampled location. At Pueblo, δ18O co-variance remains poor in samples with low TOC Colorado, the three events occur over a c. 4.5 m interval that from Beds C–H. It is uncertain why the lower part of the spans the CTB, in the stratigraphic order of LO A. albianus, succession may be preferentially affected by diagenesis. The LO H. chiastia and LO R. asper (Fig. 10). Bralower (1988) range of δ13C and δ18O values from Melton Ross appear suggested that slow sedimentation rates, a probable hiatus consistent with bulk stable isotope values from coeval between Bed H and the Turnus Bed, and subsequent European Cenomanian–Turonian sections that record a 2– bioturbation may have ‘smeared’ these events at South 5‰ positive carbon isotope excursion (CIE) associated with Ferriby and Elsham, while at Dover they occur in proximity OAE-2 (Fig. 11). The δ13C profile from Beds A–H at Melton to a lithological change to the hard, condensed limestone of Ross broadly correlates with that assigned to OAE-2 at South the Ballard Cliff Member that overlies the Plenus Marls. Ferriby (Schlanger et al. 1987; Hart et al. 1991; Clarkson et al. 2018), which also shows highest δ13C values in Beds A Stable isotopes and B and an overall decreasing trend in values through Beds Before discussing the possible stratigraphic significance of C to H, with a relatively minor, terminal peak around Bed G/ the measured changes in the δ13C stable isotope record, H. The South Ferriby studies sampled metres of chalk below diagenetic or local lithological influences have to be and above Beds A–H, and indicated c. 1‰ lower δ13C excluded. Diagenetic alteration is commonly observed in background values below and c. 0.5‰ lower background fine-grained carbonate sedimentary rocks. Deep burial values above. Therefore, although the δ18O record may have cementation and recrystallization can result in the addition been influenced by diagenesis, the δ13C signal appears less of isotopically depleted calcite to the bulk carbonate pool, impacted and possibly reflects a primary palaeoceanographic shifting the bulk δ18O record towards lower values (e.g. signal. A similar conclusion was drawn by Hu et al. (2012) Jarvis et al. 2011, 2015). However, during burial diagenesis, and Mitchell (2019) for the chalks and marls from the carbon isotope values are less prone to diagenetic alteration Northern Province. than oxygen isotope values as the carbon isotope system is The detailed profile of the CIE associated with OAE-2 has rock-dominated and δ13C is subject to a much smaller been shown to correlate across the Southern Province in temperature-controlled fractionation (Marshall 1992). A England, including Dover and Eastbourne (Jarvis et al. cross-plot of δ13C and δ18O allows the elucidation of the 2006), with Eastbourne being taken as the principal reference depositional and post-depositional controls on stable isotope section (Paul et al. 1999). It has also been correlated inter- values, with a strong co-variance between δ13C and δ18O regionally, particularly with the USA (e.g. Gale et al. 1993; indicating potential diagenetic influence (Fig. 11). Joo and Sageman 2014; Eldrett et al. 2015a; Fig. 10), In general, the stable isotope results for the Melton Ross Morocco (Tsikos et al. 2004; Jenkyns et al. 2017), Japan section show poor co-variance (R2 = 0.0076), indicating (Uramoto et al. 2013) and other areas of Europe (Jarvis et al. limited diagenetic overprint. However, the samples from 2015). In Misburg outcrop (Hilbrecht 1986), Gröbern core Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

108 P. Dodsworth et al.

(Voigt et al. 2006) and Wunstorf core (van Helmond et al. organic-rich deposits, including eastern England (South (2015), NW Germany, background δ13C values are recorded Ferriby, 0.79–3.15% TOC) and NW Germany (1.2–2.8% in the pre-Plenus sequence while peak values associated with TOC; Schlanger et al. 1987). The new HI data from the >1% OAE-2 occur within the Plenus Bed. The new record of peak TOC dark mudstones at Melton Ross plot around the lower δ13C values in the Central Limestone at Melton Ross end of this range (78–203 mg HC/g TOC; Fig. 9), consistent supports its correlation with the Plenus Bed, as initially with a relatively large terrigenous component. Jenkyns predicted by Wood and Mortimore (1995). The magnitude (1985) noted that there appears to be a general trend of an and top of the δ13C excursion vary across NW Germany increase in preservation of organic carbon as the depositional (Hilbrecht et al. 1992), but it shows an overall decreasing environment deepened from stable, relatively shallow shelf trend through the Fish Shale at Misburg and Wunstorf, to rifted graben and deeper continental margin. Higher TOC possibly correlating with that seen through Beds C to H at values have since been reported from the Black Band farther Melton Ross and South Ferriby. north in eastern England, from Speeton (13% TOC, In the Southern Province of England, a ‘build-up phase’ of Farrimond et al. 1990) and Flixton (4.5–10.2% TOC, Jeans overall increasing δ13C values through Beds 1–2 of the et al. 1991) at the edge of the Cleveland Basin (Fig. 2). Plenus Marls precedes a lower peak (‘a’) around Bed 3, a Herbin et al. (1986) reported 30% TOC from the Black Band relatively thick limestone unit. Praeactinocamax plenus Bed in the Central Graben of the North Sea, including large occurs in the overlying part of the Plenus Marls (Beds 4–8), quantities of Type III organic matter, consistent with a particularly in Bed 4 (Jefferies 1962, 1963). Above a trough substantial terrigenous component. In palynological assem- in δ13C values through Beds 4–8, a second and maximum blages from Melton Ross and other onshore Black Band peak (‘b’) occurs close to the boundary between the Plenus localities, marine organic-walled phytoplankton dominate Marls and overlying Ballard Cliff Member. Above peak ‘b’, over terrigenous pollen and spores (Supplementary Table I), δ13C values remain high but there is an overall decline in although at Flixton, the latter compose approximately one values across the CTB, through the Ballard Cliff Member, half of the assemblages from Bed C. including some prominent marl seams (Mead Marls 1–6), below a final OAE-2 peak ‘c’ (Jarvis et al. 2006). The Cyclonephelium compactum–membraniphorum In terms of correlation between the Northern Province and issue Southern Province in England, our new δ13Cdatafrom The southward incursion of abundant Cyclonephelium Melton Ross could be interpreted as follows. The three (>3‰) compactum–membraniphorum into Central Europe has peaks of δ13C in Beds I–VII may be ‘precursor’/build-up been attributed to a stressed marine environment associated events to OAE-2, correlating with southern England Beds 1– with oceanic anoxia (Marshall and Batten 1988; Courtinat 2; the base of the >4‰ interval in Bed A (Central Limestone) et al. 1991; Hart et al. 1991). However, its initial migration equals peak ‘a’ of Jarvis et al. (2006; southern England Bed has more recently been correlated with the PCE, including 3); lower Bed B may correlate with part of Beds 4–8in sites outside Europe. The latter include a proto-Atlantic southern England, supported by the record of P. plenus at coastal setting in New Jersey (Bass River; van Helmond et al. Melton Ross, Site 1 (Wood et al. 1997; Figure 4); the top of 2014; Fig. 1) and the Western Interior Seaway of the USA the >4‰ interval in upper Bed B equals peak ‘b’ of Jarvis (e.g. Portland-1 core, central Colorado; Iona-1 core, SW et al. (2006); the trough in Beds C–F and peak in Bed G may Texas; Eldrett et al. 2014, 2017; van Helmond et al. 2016; correlate with the trough through the Ballard Cliff Member Fig. 1). At Melton Ross, its basal abundant occurrence in and peak ‘c’ in southern England (Fig. 10). A comparable sample -13 is at the same level as records of correlation has been made between the δ13C profile from Beds Praeactinocamax plenus (Fig. 4) and it is consistently A–H at South Ferriby and that of the Southern Province abundant up to the top of the sampled section (sample -1). (Wood and Mortimore 1995; Clarkson et al. 2018). While the initial southward migration may have been linked Notwithstanding concerns about diagenetic alteration of to the PCE, its subsequent abundance in latest Cenomanian the eastern England Chalk Group oxygen isotope signal and Early Turonian deposits occurred during a time of discussed above, the δ18O curve from Melton Ross (Fig. 4)is extreme warmth. Its post-PCE prosperity during the OAE-2 comparable to those from other parts of Europe (cf. Jarvis interval may be related to the relative tolerance of et al. 2011, fig. 8). The minimum values in the Central areoligeracean dinoflagellate cysts in general to stressed Limestone and overlying lower Bed B may correlate with the marine environments, where their abundant occurrence is PCE. The higher values from Beds C–H could be considered often associated with nearshore environments/falls in relative consistent with subsequent warming around the CTB. The sea-level (Brinkhuis and Zachariasse 1988; Harker et al. peaks in δ18O values from the most organic-rich layers could 1990, p. 202–204; Li and Habib 1996; Olde et al. 2015b). In reflect temperature maxima and/or increased run-off during this case, the environmental stress is possibly associated with their deposition (see below). oxygen-deficient conditions in the water column and photic zone (Marshall and Batten 1988) and/or increased runoff Discussion (van Helmond et al. 2015). Organic geochemistry Samples with prominent Dinoflagellate? type D of In an overview of OAE-2 in North European shelf settings, Ioannides (1986) Jenkyns (1985) reported TOC values mainly within the range of 1–3% and HI from 150–300 mg HC/g TOC (mixed Dinoflagellate? type D occurs consistently throughout the marine and terrigenous sources) in Cenomanian–Turonian sampled section at Melton Ross, and in dominant relative Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

Melton Ross palynology and geochemistry 109 abundance (48–100% of palynological assemblages) in the In eastern England, gymnosperm bisaccate pollen are poorly preserved material from samples -20 to -17, from the invariably the dominant terrigenous palynomorph group in local Beds III?–VII. However, inspection of the absolute the Black Band and Bed G (Dodsworth 1996; this paper). abundance data (Table 3) indicates that its occurrences in The productive samples from the lower succession at Melton these beds are in the single units to tens per gramme range, Ross (samples -22 to -20; Table 2) contain few terrigenous less than its hundreds per gramme concentration estimates palynomorphs (T/M ratio 0.01 or less), which are also mainly from beds with richer recovery. It is suggested here that its bisaccate pollen. At Wunstorf, however, saccate pollen dominance in Beds III?–VII is due to its preferential constitute less than one half of the terrigenous palynomorphs preservation, probably related to a relatively thick and in most samples from the CTB succession, with trilete spores resilient wall structure. This interpretation is supported by the and non-saccate pollen often composing most of the data of Batten (in Wood et al. 1997), who reported diversified assemblage (Prauss 2006; van Helmond et al. 2015). This dinoflagellate cyst assemblages with L. siphoniphorum up to contrast between the regions probably reflects greater local Bed VI at Melton Ross, Site 2, i.e. in correlative strata a proximity to sources of detrital input in the Lower Saxony few tens of metres away (Fig. 3). Basin, as reflected by a much thicker succession there. Prauss Weathering of exposed quarry sections probably destroys (1993) noted that trilete spores show higher relative palynomorphs and other organic matter over a short time, of abundances than saccate pollen in marine deposits with months to a few years, with only central levels within the greater fluvial input because the latter are more readily Black Band being unaffected at some other sampled transported by wind (e.g. Mudie and McCarthy 1994). localities, e.g. South Ferriby and Caistor. Weathered Different hydrodynamic properties, i.e. the relative buoyancy samples contain lower concentrations of poorly preserved of saccate pollen, is probably also a factor in their differential palynomorphs, mainly those with relatively thick walls: sorting with distance from fluvial-deltaic sources (cf. Muller Dinoflagellate? type D, Kalyptea spp., prasinophyte phyco- 1959). In the Cenomanian deposits of Texas, spores form mata and indeterminate peridinioid endocysts. Samples much larger proportions of terrigenous palynomorph worst affected are marked with an asterisk in assemblages in the proximal East Texas Basin than in the Supplementary Table I. relatively distal Maverick Basin (Dodsworth 2016).

Pollen provincialism Terrigenous input Herngreen and Chlonova (1981); Herngreen et al. (1996) and In eastern England, the higher T/M ratio in relatively organic- Traverse (2007) described Late Cretaceous palynofloral rich (>1% TOC) lithologies documented here from Melton provinces. Costa and Davey (1992) reported the southerly Ross (Table 2) has previously been noted in Black Band limit of triprojectate pollen (the Aquilapollenites Province) to samples from Flixton (Dodsworth 1996, fig. 9; T/M ratio correlate approximately with the northerly siliciclastic 0.27–0.54 in 4.5–10.2% TOC samples, and 0–0.04 in 0.1– Shetland Group – southerly calcareous Chalk Group 0.4% TOC samples). Analyses from other Yorkshire sections transition in Northern Europe, around modern latitude 59° (Fig. 2) appear to confirm this pattern: East Knapton (T/M N. The rare but consistent occurrences of Normapolles pollen ratio average 0.11 in dark lithologies and 0.02 in light from the CTB succession at Melton Ross complement lithologies), Market Weighton (T/M ratio average 0.08 in previous records of their presence in the Black Band at dark lithologies and 0.01 in light lithologies) and, to a lesser Flixton, South Ferriby and North Sea well 47/10-1 (Fig. 2; extent, Bishop Wilton (T/M ratio average 0.06 in dark Dodsworth 1996). These may be the most northerly lithologies and 0.04 in light lithologies; Supplementary published Cenomanian–Turonian records in Europe (cf. Table I). This trend cannot be discerned at other Lincolnshire Peyrot et al. 2008, fig. 4) and indicate assignment of the localities (South Ferriby, Bigby and Caistor), where Bed B eastern England Chalk Group to the Normapolles Province. and Bed F/G samples are heavily weathered or barren and Normapolles pollen are a more common component of Bed D is relatively argillaceous and tentatively picked on palynological assemblages from coeval deposits farther slightly lighter-coloured marls within the Black Band. south in Europe (e.g. Bulgaria, Pavlishina and Minev At Wunstorf, Prauss (2006) calculated an average T/M 1998; Romania, Ion et al. 2004; SE France, Heimhofer ratio of c. 0.2 for the CTB succession. Prauss (2006) and van et al. 2018; Spain, Peyrot et al. 2008, 2011). In SE France, Helmond et al. (2015) also reported elevated relative and Heimhofer et al. (2018) suggested that the PCE may have absolute abundances of spores and pollen in dark coloured fostered a first spread of Normapolles-type angiosperms. mudstones compared with interbedded organic-poor lithol- Climatic conditions would have been cooler and less humid ogies, particularly within the Fish Shale (T/M ratio c. 0.2– during the PCE, possibly resulting in an open, savannah-type 0.46, in c. 1–3% TOC rocks). Van Helmond et al. (2015) vegetation community with increased abundances of interpreted this pattern as indicative of an intensified Normapolles-producing angiosperms. hydrological cycle during OAE-2, i.e. increased evaporation, precipitation and run-off during ‘black shale’ deposition, Phytoplankton productivity and preservation associated with global warming after the PCE (see also Heimhofer et al. 2018). Reworking of mud to the basin (e.g. The P-cyst Palaeohystrichophora infusorioides and the G- Jenkyns 1980) and/or the formation of swamps due to cyst Spiniferites ramosus constitute the main components of drowning of land masses (cf. Ioannides et al. 1976) during European dinoflagellate cyst assemblages from Late phases of CTB transgression could also have contributed to Cretaceous offshore/deeper water environments and upwell- the increase in spores and pollen (Dodsworth 2000). ing zones (Pearce et al. 2003; Olde et al. 2015b). The P-cyst Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

110 P. Dodsworth et al. genera Palaeohystrichophora and Subtilisphaera have been rich lithologies from, for example, the Cenomanian of the suggested as heterotrophic taxa. High numbers may reflect Western Interior (c. 0.75–0.85), and may therefore, reflect a increased nutrient availability from upwelling in the Atlantic relatively moderate increase in peridinioid productivity. Ocean off the NW African (Prauss 2012b) and European Likewise, prasinophyte increases are moderate relative to margins, and subsequent transport of nutrients via a proto- uppermost Cenomanian organic-rich mudstones in Gulf Stream to the Anglo-Paris Basin (Prince et al. 1999, Aksudere, Crimea (Fig. 1; up to 7.2% TOC; Naidin 1993), 2008; Pearce et al. 2009). Subtilisphaera pontis-mariae and where they typically constitute over half the palynomorph P. infusorioides mainly compose the high P/G ratio in assemblage (Dodsworth 2004a). Regardless of the relative Melton Ross local Beds I–?III (average 0.61). A source for contribution of organic-walled phytoplankton productivity enhanced nutrient supply during this interval is uncertain. to OAE-2, the higher proportions of E. saxoniense, The low T/M ratio is inconsistent with increased run-off. Bosedinia and prasinophytes in the >1% TOC lithologies Upwelling as a nutrient source requires a thermal difference at Melton Ross and Flixton are consistent with increased and seafloor topographical variation but there is no evidence quality of seafloor preservation in a low O2 environment. for these in eastern England. They may indicate periodic hydrographically restricted and Phytoplankton productivity during OAE-2 ‘black shale’ eutrophic conditions (cf. Eldrett et al. 2017). deposition has previously been discussed from Wunstorf. Linnert et al. (2010) studied assemblages of calcareous Palynomorph concentration nannofossils, showing a shift from a generally oligotrophic ecosystem during deposition of lighter coloured beds to Most palynological studies of Cenomanian and Turonian more mesotrophic or even eutrophic conditions during deposits report relative abundances only. Records of deposition of dark coloured mudstones. Van Helmond et al. specimen numbers per microscope slide from Dover, (2014, 2015) suggested that an acceleration of the Eastbourne and the Isle of Wight, southern England (Jarvis hydrological cycle during the warmer intervals of OAE-2 et al. 1988a; Fitzpatrick 1996) have given a semi-quantitative may have played a key role in supplying nutrients offshore indication of recovery. Until the last ten years, there have and enhancing stratification, thus contributing to the been few reports of fully quantitative concentration, counts development of ocean anoxia. Increased precipitation, run- per gramme (cpg) data. Duane (in Paul et al. 1994), using a off (reflected by a higher T/M ratio) and associated nutrients volumetric method, reported dinoflagellate cysts in the may have contributed to productivity of organic-walled hundreds (mainly 100–800 cpg) range from Middle phytoplankton during deposition of the dark coloured layers Cenomanian chalks and marls in the Dover–Folkestone in eastern England. Warren area, southern England. Pearce et al. (2003), using a Within the Black Band and Bed G at Melton Ross, method involving adding a known number of Lycopodium common Eurydinium saxoniense and Bosedinia cf. sp. 1 of spores to samples (Stockmarr 1971; Mertens et al. 2009), Prauss (2012b) and rare Bosedinia laevigata,makeagreater reported dinoflagellate cysts in the tens to 600 cpg range from contribution to the P/G ratio in the >1% TOC samples Turonian chalks and marls at Banterwick Barn, southern (Table 4). Eurydinium saxoniense was initially described in England. higher relative abundances in dark coloured mudstone layers Much higher concentrations of palynomorphs (mainly from Wunstorf and Misburg by Marshall and Batten (1988), dinoflagellate cysts) were reported from Upper Cenomanian who associated it with a stressed marine environment with a deposits in southern England, at Eastbourne and Lulworth. low level of oxygen extending high up the water column. Pearce et al. (2009), using the Lycopodium method, reported High relative abundances of Bosedinia spp. in Late c. 50 000–75 000 cpg from six marl and chalk samples over a Cretaceous marine settings have been interpreted as reflect- 10 m interval below the Plenus Marls at Eastbourne. ing reduced salinity surface water and enhanced density Dodsworth (2000), using this study’s volumetric method, stratification (at Tarfaya; Prauss 2012b, fig. 5), and/or reported nearly 38 000 cpg from a marl sample one metre increased nutrient (nitrite/nitrate) availability from oxygen- below the Plenus Marls at Lulworth. Pearce et al. (2009) deficient waters encroaching into the photic zone (in the noted that assemblages from below the Plenus Marls at both Western Interior of the USA and Demerara Rise; Dodsworth localities are dominated by the P-cyst Palaeohystrichophora 2016; Eldrett et al. 2017). In the Black Band and Bed G, infusorioides. They attributed its high concentrations to higher numbers of E. saxoniense and Bosedinia spp. occur in upwelling in the Atlantic Ocean off the European and NW the absence of fresh/brackish-water algae and may record African margins, with associated nutrients being transported some stimulation of dinoflagellate productivity by increased to the southern England area by dominantly southwesterly supply of reduced nitrogen chemo-species in photic-zone surface winds and ocean surface currents. Both Dodsworth waters (cf. Prauss 2007). This is supported by the relative (2000) and Pearce et al. (2009) documented overall increase in prasinophyte phycomata in the darker layers at decreasing concentrations of palynomorphs through the Melton Ross, Flixton (5.7–9.3% in Bed C, 14% in Bed E; Plenus Marls (to just over 100 cpg in Bed 8 at Lulworth) Dodsworth 1996) and Wunstorf (up to 15%; Prauss 2006). and barren or impoverished recovery in the overlying Ballard Prasinophyte prosperity may be mainly related to product- Cliff Member. Jarvis et al. (1988a); FitzPatrick (1996) and ivity stimulated by introduction of nitrogen/ammonium- Pearce et al. (2003) also reported a palynologically barren or enriched waters of the denitrification zone into the photic impoverished interval above the Plenus Marls at other zone (Prauss 2006, 2007). However, the average P/G ratio at southern England localities, with better palynological Melton Ross (0.33) in the >1% TOC samples is much lower recovery from Turonian chalks and marls above the Ballard than that discussed above for Bosedinia-dominated organic- Cliff Member and Holywell Member. Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

Melton Ross palynology and geochemistry 111

Dodsworth (2000) attributed poor palynological recovery Jeans et al. 1991; Mitchell 2000) at Flixton and Speeton, from the upper part of the Plenus Marls and the Ballard Cliff with average phytoplankton concentrations of c. 95 000– Member to upward coarsening through the succession 100 000 cpg, and pollen and spores c. 10 000 cpg at Speeton (Hancock 1989; Jeans et al. 1991; Lamolda et al. 1994) and c. 80 000 cpg at Flixton (Supplementary Table I). These and the associated reduced palynomorph preservation regional data appear to be consistent with the trend of an potential of lithologies with a relatively high coarse silt and increase in preservation of organic matter as the depositional sand grade component. Pearce et al. (2009) acknowledged environment deepened from relatively shallow shelf to this but, following Jarvis et al. (1988a); FitzPatrick (1996) deeper continental margin (Jenkyns 1985). Unlike the and Lamolda and Mao (1999), suggested that a primary samples below the Plenus Marls at Eastbourne and decline in phytoplankton productivity across the CTB in the Lulworth, which also contain high concentrations of Anglo-Paris Basin may have been an additional cause of the dinoflagellate cysts (c. 38 000–75 000 cpg; see above), P. low recovery. The Eastbourne and Lulworth localities record infusorioides is a relatively minor component of assemblages a marked decrease in the relative and absolute abundance of from dark coloured mudstones in eastern England (Table 4), P. infusorioides above Bed 4 of the Plenus Marls, consistent suggesting that nutrients originating from upwelling might with a decrease in nutrient supply (Pearce et al. 2009). An not have been the cause of high concentrations of overall decline in the nannofossil fertility index also occurs dinoflagellate cysts there. between Bed 4 and Ballard Cliff Member (Gale et al. 2000). The fact that the Wunstorf and Misburg sections are at Palynomorph concentration data are becoming more least ten times as thick as the correlative eastern England frequently available from areas outside southern England. sections, yet show a succession of dinoflagellate cyst and From the CTB succession at Bass River, New Jersey, van acritarch bio-events comparable to those at Melton Ross, is Helmond et al. (2014), using the Lycopodium method, consistent with a high degree of stratigraphic condensation in reported dinoflagellate cysts in the 2000–30 000 cpg range, eastern England. The greater palynomorph concentrations and terrigenous spores and pollen in the 400–11 000 cpg documented from the dark coloured mudstones in eastern range, from silty clay to clayey silt lithologies (0.61–1.51% England may partly reflect this, along with increased quality TOC) that were deposited in an inner neritic setting. From the of seafloor preservation (in a low O2 environment), CTB succession in Wunstorf core, van Helmond et al. particularly in potential local topographic troughs in the (2015), also using the Lycopodium method, reported seafloor and in deeper areas of the continental shelf. A loss of dinoflagellate cysts mainly in the 1000–15 000 cpg range biogenic carbonate sediment during the CTB mass extinction and terrigenous spores and pollen in the 2500–5000 cpg interval, and a reduction of siliciclastic input during range, from samples with 0.5–3% TOC. Using this study’s maximum flooding associated with the base of the Black volumetric method, comparable values for organic-walled Band (eastern England; Wood et al. 1997) and the correlative phytoplankton were obtained from the CTB succession at base of the Fish Shale (NW Germany; Ernst et al. 1984), may Aksudere, Crimea, 3520–20 400 cpg, from samples with also have contributed to stratigraphic condensation and 0.3–7.2% TOC (Dodsworth 2004a). Comparable values enhanced palynomorph concentration. have also been obtained from relatively unweathered dark Palynomorphs are recovered from most levels within the coloured mudstones of the Black Band at South Ferriby and Chalk Group of the Southern Province (Anglo-Paris Basin; Caistor; average phytoplankton is in the range of 10 000– see examples above) and the Transitional Province, e.g. the 15 000 cpg with pollen and spores at 200–900 cpg Trunch borehole (Fig. 2) that has palynological recovery (Supplementary Table I). throughout the Upper Cretaceous section apart from a Significantly higher concentrations of palynomorphs have Middle Cenomanian to Middle Turonian barren interval been recorded from the dark coloured mudstones of the (Pearce 2010, 2018; Olde et al. 2015a; Pearce et al. 2020). Black Band and Bed G elsewhere in Lincolnshire, at Melton All chalk samples analysed to date from the Cenomanian and Ross (average phytoplankton c. 84 000 cpg; pollen and Lower Turonian of the Northern Province, below and above spores c. 10 000 cpg; Table 2) and Bigby (average the Black Band, and from the Central Limestone at Melton phytoplankton c. 60 000 cpg; pollen and spores c. 3500 Ross (this study), are palynologically barren. This is also the cpg). These values may be more representative than those case for chalk samples from the CTB interval in NW from South Ferriby and Caistor, given that samples from the Germany (Marshall and Batten 1988; Prauss 2006; van latter sections are apparently more affected by quarry wall Helmond et al. 2015). In the North Sea Basin, poor or patchy weathering. However, the relatively expanded sections at palynological recovery from the Chalk Group has led to Melton Ross and Bigby could have been deposited in local palynology not being routinely used in stratigraphic studies topographic troughs in the seafloor (Gaunt et al. 1992; Wood of hydrocarbon wells (with exceptions such as Maastrichtian and Mortimore 1995; Wiese et al. 2009), in which organic chalk in the Dan Field, Danish sector; Schiøler and Wilson matter preservation may have been enhanced (cf. Jenkyns 1993), whereas it is a primary stratigraphic discipline in the 1985). Farther north in Yorkshire, average phytoplankton coeval northerly, siliciclastic Shetland Group, which has concentrations from relatively unweathered dark coloured consistent rich palynological recovery (Costa and Davey mudstones of the Black Band and Bed G are c. 40 000– 1992). In England, a different diagenetic history of 50 000 cpg at Market Weighton, Bishop Wilton and East Cenomanian and Turonian chalks in the Northern Knapton, with pollen and spores at c. 3500–5000 cpg; i.e. Province, which are hardened relative to those of the values relatively comparable to Melton Ross and Bigby. The Transitional and Southern Provinces (Jeans 1980; Jeans highest concentrations of palynomorphs in the region are et al. 2014), probably contributed to post-depositional loss of from sections on the margins of the Cleveland Basin (e.g. palynomorphs. Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

112 P. Dodsworth et al.

Fig. 12. The stratigraphy of the Cenomanian–Turonian boundary interval in Norwegian Continental Shelf, North Viking Graben exploration well 35/6-2 S (‘Grosso’), drilled by StatoilHydro AS in 2009. The proposed correlation to onshore outcrops is discussed in the main text. Shetland Group lithostratigraphy of Gradstein and Waters (2016), dinoflagellate cyst zones and subzone of Olde et al. (2015a) and Dodsworth and Eldrett (2019). The last occurrence (LO) of Carpodinium obliquicostatum is taken here as a proxy for the top of the Adnatosphaeridium tutulosum Subzone. FO = First occurrence; NWG = NW Germany; GR = gamma ray, American Petroleum Institute (API) units.

Correlation with Norwegian sector well 35/6-2 S Conclusions Ditch cuttings samples from the Grosso exploration well 35/ A sequence of dinoflagellate cyst and acritarch bio-events 6-2 S in the Norwegian sector, North Viking Graben supports the proposed correlation of the Melton Ross CTB (Shetland Group facies; Figs 1 and 12) were analysed for succession with sections in NW Germany. The top of palynology by one of us (PD) in 2009. The well has a consistent/common Litosphaeridium siphoniphorum occurs relatively thick (37 m) Blodøks Formation gamma log profile in the lower succession at Melton Ross and the pre-Plenus that probably correlates with the more expanded outcrop beds at Misburg and Wunstorf; the base of abundant lithological successions discussed in this paper. Cyclonephelium compactum–membraniphorum occurs A sharp rise in gamma log values marks the base of the immediately above the Central Limestone at Melton Ross, Blodøks Formation at 2657 m (log depth). The LO of in lower Bed B, and immediately above the Plenus Bed at consistent/common Litosphaeridium siphoniphorum, and Misburg and Wunstorf; a regional influx of rare Pterodinium crassimuratum at 2655 m, indicate the Oligosphaeridium totum, with an acme in upper Bed B at probable presence of the pre-Plenus succession. A fall in Melton Ross, occurs at the same level as a record of the latest gamma log values from 2650.4 m to 2648.6 m may correlate Cenomanian zonal ammonite Neocardioceras juddii at with the Plenus Bed in NW Germany and Central Limestone/ Misburg; rare specimens of the dinoflagellate cysts Bed A in eastern England. This is supported by the FO of Adnatosphaeridium tutulosum and Carpodinium obliquicos- common Cyclonephelium compactum–membraniphorum, tatum have their range tops in or just above the Black Band in Eurydinium saxoniense and Alterbidinium daveyi in the eastern England, and within the Fish Shale at Misburg and next up-hole sample from 2646 m, in an interval of rising Wunstorf. An influx of the acanthomorph acritarch gamma log values from 2648.6 m to 2641.7 m (likely Micrhystridium spp. in Bed G at Melton Ross may correlate equivalent of eastern England Bed B). The remainder of with that recorded from the upper parts of the Fish Shale at the Blodøks Formation from 2641.7 m to 2620.0 m contains Wunstorf. two gamma log plateaux, separated by a lower gamma Correlation between eastern and southern England is less interval, probably correlative with the relatively clay- and straightforward. Carbon isotope data from Melton Ross and organic-rich Fish Shale in NW Germany and Beds C to H in South Ferriby, and the distribution of dinoflagellate cyst bio- eastern England. This interpretation is supported by the LO events, support the interpretation that the Black Band is of Carpodinium obliquicostatum from a cuttings sample near stratigraphically higher than the Plenus Marls. The restriction the top of the formation at 2616 m. Common C. compactum– of Praeactinocamax plenus (belemnite) to the Plenus Marls membraniphorum, E. saxoniense and A. daveyi persist higher and Neocardioceras juddii (ammonite) to the overlying than the log pick for the top of the Blodøks Formation. The Ballard Cliff Member are consistent with this. The highest common occurrence of C. compactum–membrani- correlation points to separate depositional histories and phorum is often used as a proxy for the top of the Lower marked differences in siliciclastic input between the Turonian (Dodsworth and Eldrett 2019), occurring in this Northern and Southern Provinces during post-Plenus Marls well at 2466 m. Rugubivesiculites rugosus occurs sporadic- times. However, the foraminiferal and calcareous nannofos- ally in eight samples in the Turonian interval, from 2256 m, sil data can alternatively be interpreted in terms of the Black but is more consistent in Cenomanian deposits from 2646 m Band being equivalent to the upper part of the Plenus Marls. and below. Poor preservation and/or recovery of all three microfossil Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

Melton Ross palynology and geochemistry 113 groups in the Ballard Cliff Member hampers confident not validly published (Fensome et al. 2019). Subsequently, assessment of correlative bio-events around the CTB in the genus Alterbia has been considered an illegitimate name southern England. and its species have been transferred to the genus Palynological assemblages from the >1% TOC samples at Alterbidinium (Fensome et al. 2019). Alterbidinium Melton Ross contain higher relative abundances of the P- ‘daveyi’ has become widely accepted as a separate but cysts Eurydinium saxoniense and Bosedinia spp., along with informal species. The designation herein of one of the prasinophyte phycomata, consistent with periodic hydro- specimens illustrated in Davey (1970) as a holotype, gives it graphically restricted and eutrophic conditions during formal status. deposition of the darker mudstone layers. Exceptionally Alterbidinium daveyi and Eurydinium saxoniense have high concentrations of palynomorphs suggest enhanced comparable morphology, and both possess a single intercal- preservation in such a low O2 environment at the ary (2a) plate archaeopyle that is steno- to iso-deltaform. sediment–water interface coupled with a high degree of Alterbidinium daveyi may be slightly larger (cf. length, 52– stratigraphic condensation. This is in agreement with the 66 µm, and width, 37–54 µm for E. saxoniense; Marshall and view of Hart and Leary (1989), who suggested that the Black Batten 1988) and appears to have a more strongly developed Band was deposited during ‘sluggish’ oceanic conditions apical horn and cingulum than E. saxoniense, but inter- that would have been ideal for the concentration and gradations may occur. The cingulum in A. daveyi is marked preservation of organic-rich sediments, with or without by low ridges that sometimes possess pustules distally and is high surface-water productivity. occasionally crossed by low ridges delimiting plate bound- aries (Davey 1970, p. 338); the latter features are not reported in E. saxoniense. The holotype of A. daveyi appears to show Systematic palaeontology some anterior dorsal intercalary tabulation (2a and 3a plate Division DINOFLAGELLATA (Bütschli, 1885) Fensome boundaries). Dorsal tabulation is usually restricted to the et al., 1993 archaeopyle in E. saxoniense (Marshall and Batten 1988), Class DINOPHYCEAE Pascher, 1914 though our illustrated specimen (Fig. 5.6) may possess Order PERIDINIALES Haeckel, 1894 sutures around both 2a and 3a intercalary plates. Suborder PERIDINIINEAE (Autonym) The eastern England specimens inspected in this paper and Family PERIDINIACEAE Ehrenberg, 1831 previous studies have been assigned to E. saxoniense, Genus Alterbidinium Lentin and Williams, 1985 although the additional presence of A. daveyi cannot be Type species: Alterbidinium ‘recticorne’ ruled out. The dinoflagellate cyst distribution charts of (Vozzhennikova, 1967) Harker et al., 1990 Marshall and Batten (1988) indicate an absence of A. daveyi and the common to abundant occurrence of E. saxoniense Alterbidinium daveyi basionym nov. from the (post-Plenus) CTB interval in NW Germany. Conversely, in coeval deposits from North America, A. Derivation of name. In honour of the palynologist Roger daveyi (sometimes recorded as S. pirnaensis) is prominent J. Davey. (Bloch et al. 1999, fig. 23; Dodsworth 2000, 2016; Harris Designation of holotype. Davey (1970, plate 1, fig. 3). and Tocher 2003; Dodsworth and Eldrett 2019). In the Location, International Yarbo Borehole no. 17, SE Shetland Group of Northern Europe, both A. daveyi and E. Saskatchewan, Canada (coordinates supplied by Davey saxoniense are common, e.g. in Norwegian well 35/6-2 S, 1969, p. 115, fig. 8, are; ‘east of Regina at Lsd. 1, Sec. 24, where confident differentiation between the species can be Twp. 20, Rg. 33, W1st Meridian’). Sample depth 254.5 m problematic for some specimens. (835 ft) below Kelly Bushing, Second White Specks Shale, Colorado Group. The slide is curated at the Natural History Genus Bosedinia He, 1984, emend. Chen et al., 1988, Museum, London (slide/specimen reference number Prauss, 2012 V.51979). Type species: Bosedinia granulata (He and Qian, 1979) Description. See Davey (1970, p. 338). He, 1984 Discussion. Davey (1970, pl. 1, figs 3, 4, p. 338) described specimens from Cenomanian deposits in Saskatchewan that Bosedinia laevigata (Jiabo, 1978, ex He and Qian, 1979) he assigned to Deflandrea (now Subtilisphaera) pirnaensis. He, 1984 He pointed out differences with the type material of S. pirnaensis, as described by Alberti (1959) from Turonian Figures 7.11, 7.12, 7.13, 7.17, 7.21 deposits in Germany, including a smaller size, length 46 (62.7) 87 µm (compared with 80–106 µm) and width, 34 Description. Small to intermediate-sized, sub-spheroidal (45.5) 63 µm (compared with 58–64 µm), and presence of an shaped, smooth and thin-walled proximate autocysts with an archaeopyle in many Saskatchewan specimens but absence ornament of c. 10–50 sparsely distributed, non-tabular, solid of one in the type specimens. It is also noted here that the verrucae, each of which is c. 1–3 µm in diameter. Tabulation holotype of S. pirnaensis (Alberti 1959, pl. 8, fig. 1) has is indicated by an archaeopyle only. A flap-like operculum, possible pre- and postcingular tabulation that is absent from probably involving fused apical and anterior intercalary the Saskatchewan specimens. Stover and Evitt (1978) plates, is often attached. Inclusions (omphali) are present in proposed a new species, Alterbia daveyi, based on the some specimens. specimens illustrated in Davey (1970) but did not designate Dimensions. Diameter (central body, 12 measured speci- one of the specimens as a holotype. The name was therefore mens): 35.7 (43.5) 56.0 µm. Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

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Discussion. The type specimens of Bosedinia laevigata plates (1a–3a), often attached, and sutures are usually present (He et al. 2009, pl. 17, figs 11–15), from lacustrine Neogene between precingular plates that are attached at the cingular deposits in China, are of comparable size (35–60 µm border (3I3Pa). Prauss (2006) noted that Ginginodinium?sp.A diameter) to the specimens measured from Melton Ross, and probably includes specimens informally described as ‘Cyst contain a comparable number, size and distribution of small form A’ by Marshall and Batten (1988). The type species, verrucae ornament. Bosedinia laevigata has been recorded Ginginodinium spinulosum (Cookson and Eisenack 1960,p.7, from marine Upper Cretaceous deposits at Tarfaya, Morocco pl. 2, fig. 9), and other accepted species, sometimes exhibit (Prauss 2012c, 2015) and the Abu Gharadig Basin in Egypt accessory sutures on dorsal precingular plates, in addition to a (Ahmed et al. 2020; Figure 1), but not previously in Europe. three plate intercalary archaeopyle (Stover and Evitt 1978). In Stratigraphic range/occurrence. At Melton Ross, Bed C the Melton Ross material, consistent differentiation of this (sample -11.5) to Bed E (sample -8). taxon from T. suspectum was problematic. Stratigraphic range/occurrence. At Melton Ross, local Bosedinia cf. sp. 1 of Prauss (2012b) Bed I (sample -22) to Bed H (sample -1).

Figures 7.5, 7.9, 7.10 Genus Subtilisphaera Jain and Millepied, 1973, emend. Lentin and Williams, 1976 Discussion. The abundant occurrence of mainly enclosed Type species: Subtilisphaera senegalensis Jain and spheres, containing omphali, in organic-rich Cenomanian– Millepied, 1973 Coniacian deposits at Tarfaya, has been discussed by Prauss (2012a, b, c, 2015). Prauss (2012b) provided evidence for Subtilisphaera pontis-mariae (Deflandre, 1936) Lentin their assignment to the genus Bosedinia from occasional and Williams, 1976 specimens that have an archaeopyle/operculum. Eldrett et al. (2017) documented the abundant occurrence of comparable Figures 5.14, 5.15 specimens at other proto-Atlantic sites (Demerara Rise, DSDP Sites 1260 and 1261; Fig. 1) and within the Western Description. Small to intermediate-sized, elongate to Interior Seaway of the USA (SW Texas and central ovoidal-shaped, smooth-walled, bicavate to circumcavate Colorado). Specimens from Melton Ross constitute the first peridinioid dinoflagellate cysts with pericoels developed into record of their presence in Europe. However, there are issues a sub-conical apical horn and one similar antapical horn that with consistent identification. While the specimen illustrated is positioned asymmetrically. The epicyst is larger than the in Figure 7.9 shows a rare example of discernible anterior hypocyst. The cingulum is delimited by two low ridges. An intercalary and apical plates being involved in operculum archaeopyle has not been observed. The endocyst is sub- formation, consistent with Bosedinia, the fully enclosed spherical and slightly thicker walled than the periphragm. specimen in Figure 7.10 could alternatively be interpreted as The horns are approximately 1/5 to 1/4 of the diameter of the an endocyst of Subtilisphaera pontis-mariae. (cf. the speci- endocyst. mens in Figs 5.14, 5.15). The two overlapping specimens in Dimensions (seven measured specimens). Length 47.3 Figure 7.5, resemble Eyrea nebulosa, which also possesses (52.7) 57.0 µm; width 32.6 (36.0) 42.2 µm. omphali (cf. plate 11, in Cookson and Eisenack 1971), but Discussion.TheSubtilisphaera specimens encountered in may be distinguished by the presence of a kalyptra, when the present study have comparable morphology, with some preserved. In the Melton Ross data, specimens encountered variation in the degree of cavation and the length of horns. are mainly single enclosed spheres with omphali and have They are recorded here as Subtilisphaera pontis-mariae.The been assigned to ‘Bosedinia cf. sp. 1/peridinioid endocysts’ holotype (Deflandre 1936, pl. 2, fig. 7) is closely comparable in the supplementary distribution chart. to the Melton Ross specimen illustrated in Figure 5.14.Some Stratigraphic range/occurrence. At Melton Ross, local subsequently illustrated specimens (e.g. Davey 1970, pl.1, figs Bed II (sample -21) to Bed H (sample -1). 10–11; Dodsworth 2016, pl. 1, fig. 7) differ slightly in having longer horns, c. 1/2 to 1/3 the diameter of the endocyst. While Genus Ginginodinium Cookson and Eisenack, 1960, Dodsworth (1996, 2000) used Subtilisphaera spp. for eastern emend. Lentin and Williams, 1976 and southern England specimens from the CTB interval, other Type species: Ginginodinium spinulosum Cookson and workers in eastern England (Marshall and Batten 1988; Hart Eisenack, 1960 et al. 1993), southern England (FitzPatrick 1995; Pearce et al. 2009) and northern France (Foucher 1979) have considered Ginginodinium? sp. A of Prauss 2006, 2012a the range of morphological variation of Subtilisphaera specimens to fall within acceptable intra-specific limits for Figures 6.3, 6.7 S. pontis-mariae in material of this age. However, Foucher (1980) assigned the latest Cenomanian specimens to S. cf. Discussion. In Cenomanian and Turonian deposits from pontis-mariae in the Boulonnais region of northern France. NW Germany (Wunstorf) and Morocco (Tarfaya), Prauss Stratigraphic range/occurrence. At Melton Ross, local (2006, 2012a) differentiated specimens that are morphologic- Bed I (sample -22) to Bed H (sample -1). ally close to Trithyrodinium suspectum but with a more complex archaeopyle, tentatively assigning them to the genus Genus Trithyrodinium Drugg, 1967, emend. Davey, 1969, Ginginodinium. The archaeopyle in Ginginodinium?sp.A Lentin and Williams, 1976, Marheinecke, 1992 involves from one intercalary plate (2a) to three intercalary Type species: Trithyrodinium evittii Drugg, 1967 Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

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Trithyrodinium maculatum sp. nov. Description. Small to intermediate-sized, sub-polygonal to peridinioid-shaped, smooth and thin-walled cysts that lack Figures 7.14, 7.15, 7.18, 7.19 ornament. Peridinioid tabulation is indicated by sutures or breaks between some plates on the epicyst, indicating three anterior intercalary plates. An archaeopyle has not been Derivation of name. From maculate, meaning spotted or observed. A periphragm has not been observed. There is no stained, with reference to the distinctive surface markings. evidence of tabulation, other than indicated by the sutures. Designation of holotype. Figure 7.18. Sample MR3. Dimensions (length × width). First specimen, 46.5 × Slide MR3(A). Coordinates S32/3. Location, Melton Ross 40.7 µm; second specimen, 54.3 × 50.0 µm. Quarry, Lincolnshire, UK. Stratum, Bed F, Flixton Member, Discussion. Prauss (2012a, fig. 15) illustrated an unpub- Welton Chalk Formation. The specimen is curated in the lished smooth, thin-walled species of Trithyrodinium at MPK collection of the British Geological Survey, Keyworth, Tarfaya that usually has sutures around three intercalary Nottingham, UK, specimen number MPK 14662. plates and rarely possesses a periphragm (Prauss 2012a, fig. Diagnosis. A species of Trithyrodinium possessing an 15J). It is uncertain whether this taxon is the same as the ornament of ring-shaped indentations on the endophragm Melton Ross specimens described here. and periphragm. Stratigraphic range/occurrence. At Melton Ross, Bed C Description. Small to intermediate-sized, spheroidal to (sample -11) to Bed G (sample -2). ovoidal-shaped, circumcavate, peridinioid dinoflagellate cysts. The endophragm (c. 1 µm thick) and periphragm (c. Order GONYAULACALES Taylor, 1980 0.5 µm thick) are smooth to finely-granular, both possessing Suborder GONYAULACINEAE (Autonym) regular ornament elements that are circular to sub-circular, Family GONYAULACACEAE Lindemann, 1928 ring-shaped indentations (c. 3–6 µm diameter), which are at Genus Dissiliodinium Drugg, 1978 least half the thickness of the surrounding wall areas. Type species: Dissiliodinium globulus Drugg, 1978 Cavation is c. 2–3 µm wide at the lateral margins and up to 10 µm in the antapical region. An archaeopyle involving ?Dissiliodinium globulus Drugg, 1978 three anterior intercalary plates, type 3I(1–3a), is formed in the endocyst, with operculum plates attached or detached. The 2a Figures 7.4, 7.8 intercalary plate is isodeltaform, hexa-type (Fig. 7.19; cf. text-figure 6 in Bujak and Davies 1983). The periarchaeopyle Description. Intermediate-sized, spheroidal-shaped, type has not been confirmed. There is no evidence of smooth and thin-walled proximate autocysts lacking orna- tabulation, other than that indicated by the archaeopyle. ment. Tabulation is indicated by sutures between precingular Dimensions (length × width of the endocyst). Holotype, plates on the epicyst. Archaeopyle formation involves one or 39.6 × 42.5 µm. Other specimens (5 measured): length 38.0 more precingular plate. There is no evidence of tabulation on (50.0) 66.9 µm, width 39.5 (45.6) 55.3 µm. the hypocyst. Discussion. Only six specimens of this taxon have been Dimensions (four specimens measured). Diameter: 57.0 recorded to date. However, its distinctive morphology makes (60.7) 65.0 µm. it easy to identify and warrants the erection of a formal Discussion. The observed features of the four available species. The endocyst archaeopyle type is consistent with the specimens allow tentative assignment to Dissiliodinium genus Trithyrodinium but an outer wall layer (periphragm) globulus. The taxon has been documented from the Upper has only been observed on two specimens, including the Jurassic of Central Europe (Drugg 1978) and Northern holotype. The circular indentations on the cyst walls are ring- Europe (e.g. Bailey et al. 1997) and is present in higher shaped, as opposed to the whole area within the circle being proportions within the Lower Cretaceous of SW Morocco thinned. The ring shapes are reminiscent of those attributed (Below 1981). Prauss (2012b, fig 9a–i) reported specimens to impressions made by coccoliths on the surface of from around the CTB at Tarfaya. specimens of an alga (Campenia sp.) by Prauss (2012b, Stratigraphic range/occurrence. At Melton Ross, Bed E figs 10A, 11H). However, the T. maculatum specimens occur (sample -8 only). in assemblages of abundant dinoflagellate cysts, with other taxa not exhibiting comparable markings. The markings are a Genus Leptodinium Klement, 1960, emend. Stover and key identifying feature but could be a preservation artefact. Evitt, 1978, Sarjeant, 1982 This type of surface ornament has not previously been Type species: Leptodinium subtile Klement, 1960 reported on other species of P-cysts, including those belonging to the genus Trithyrodinium. In the G-cyst Leptodinium? aff. delicatum (this paper) species Apteodinium maculatum, comparable ring-shaped thinning surrounds small thickened circular areas (Eisenack Figure 6.12 and Cookson 1960). Stratigraphic range/occurrence. At Melton Ross, Bed B Description. Intermediate-sized, smooth and thin-walled (sample -12) to Bed F (sample -3). autocysts with sub-polygonal shape and septae (entire; c. 1.5 to 3.5 µm high) that probably correspond to tabulation. The Trithyrodinium? sp. A (this paper) cingulum appears to have strongly offset ventral ends. An archaeopyle has not been observed on the two specimens Figures 7.1, 7.2 recorded. 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Dimensions. Diameter: illustrated specimen, 61.8 µm; Genus Pterodinium Eisenack, 1958, emend. Yun, 1981, second specimen, 60.8 µm. Sarjeant, 1985 Discussion.InLeptodinium? delicatum, the wall is very Type species: Pterodinium aliferum Eisenack, 1958 thin (less than 0.5 µm thick) and only attains a thickness of 0.5 µm when forming plate boundaries (Davey 1969, p. 123). Pterodinium crassimuratum (Davey and Williams, 1966) The Melton Ross specimens resemble L.? delicatum but Thurow et al., 1988 differ in possessing sutural septae. The detailed plate formula is not yet determined. The probable offset sulcus is consistent Figure 5.7 with the genus Leptodinium though the presence of septae is more compatible with the genus Impagidinium (Stover and Discussion. Kjellström (1973) and Pavlishina (1990) Evitt 1978). considered Pterodinium? pterotum to be a senior synonym Stratigraphic range/occurrence. At Melton Ross, Bed C of Pterodinium crassimuratum and Pterodinium cingulatum (samples -11 and -11.5). subsp. polygonale.InDodsworth and Eldrett (2019, plate 1, fig. 4), specimens encountered were assigned on the basis of Genus Oligosphaeridium Davey and Williams, 1966, this proposed synonymy to P.? pterotum. However, subse- emend. Davey, 1982 quent inspection of the holotype photographs and original Type species: Oligosphaeridium complex (White, 1842) descriptions for the three taxa indicates that our specimens, Davey and Williams, 1966 both from the USA and Europe, are closest to P. crassimuratum and P. cingulatum polygonale, having Oligosphaeridium totum Brideaux, 1971 thickened intra-plate areas and ‘a linear depressed area on each side of the ledges [septae] thereby separating a more Figures 5.9, 5.10, 8.9 elevated central plate area from the ledges’ (Clarke and Verdier 1967, p. 47). We agree with Clarke et al. (1968, Discussion. The published taxon Oligosphaeridium totum p. 181) that the latter subspecies is a junior synonym of P. is considered here to accommodate a skolochorate dinofla- crassimuratum. However, Cookson and Eisenack (1958, gellate cyst from NW Germany and the North Sea that was p. 50) make no reference to comparable thickened intra-plate informally assigned by Marshall and Batten (1988) to areas in P.? pterotum, and none are visible on their holotype Litosphaeridium sp. A. The latter name was adopted in photograph (plate 11, fig. 7). We therefore conclude that P.? subsequent studies of the CTB interval in eastern England pterotum is not a senior synonym of P. crassimuratum. (Hart et al. 1993; Dodsworth 1996), southern England (FitzPatrick 1995) and Poland (Dodsworth 2004b). The Family AREOLIGERACEAE Evitt, 1963 processes of O. totum are tubular, sometimes slightly Genus Aptea Eisenack, 1958 narrower medially, with apices usually flaring, buccinate Type species: Aptea polymorpha Eisenack, 1958 and possessing an entire margin (Brideaux 1971). Two subspecies are differentiated, based mainly on process length Aptea? spongireticulata (Prössl, 1990, ex Prössl, 1992) relative to central body, O. totum subsp. totum (relatively Fensome et al., 2019 long processes, approximately two-thirds to one central body diameter in length; comparable to most specimens encoun- Figures 6.1, 6.2 tered in this study, e.g. Figs 5.9, 8.9) and O. totum subsp. minus (relatively short processes, approximately one half of Description. Intermediate-sized, lenticular-shaped cysts the central body diameter; cf. Fig. 5.10). The Melton Ross with rounded or flattened apical and antapical areas, lacking specimens have the same process formula as those described well-developed horns. The autophragm is smooth to lightly by Brideaux (1971) for O. totum and by Marshall and Batten pitted and is covered with a coarse reticulum. Rod-like (1988) for Litosphaeridium sp. A; 4I,6II, 0c, 5III, 1p, 1IIII, 1s. structures with expanded to bifurcating tips support the This is a process formula common to all species of reticulum muri and are c. 6–10 µm long. The muri are fibrous Oligosphaeridium and some species of Litosphaeridium or finely fenestrate. The lacuna between the muri vary in size, (Lucas-Clark 1984). Litosphaeridium differs from from c. 5–13 µm across. A slight indentation in the reticulum Oligosphaeridium in having dome-shaped processes that in the antapical region on one specimen (Fig. 6.1)may are typically not expanded distally (Stover and Evitt 1978). represent a gap between antapical horns. Tabulation is The type material of O. totum has a slightly thicker, more indicated by an apical archaeopyle only. scabrate central body wall than the smooth walls observed on Dimensions (five measured specimens, length × width Melton Ross specimens and those described and illustrated without operculum). Length 61.0 (66.9) 73.0 µm; width 83.8 from NW Germany (Marshall and Batten 1988, p. 92, pl. I, (86.3) 89.0 µm. fig. 9; Marshall 1983, pl. 13, figs 16, 18). However, Singh Discussion. The Melton Ross specimens conform to the (1971) reported a smooth cyst wall on Oligosphaeridium type material of A.? spongireticulata, illustrated from NW diastema, a junior synonym of O. totum (as agreed by Singh Germany by Prössl (1990). Canningia macroreticulata and Brideaux; Brideaux and McIntyre 1975, p. 29). Some differs in having smaller lacuna between its muri of c. 2– variation in thickness and ornament of the central body may 7 µm and has shorter (c. 2 µm high), entire muri without therefore be attributed to intra-specific variation. fibrous/fenestrate structure (Lebedeva, in Ilyina et al. 1994). Stratigraphic range/occurrence. At Melton Ross, local The Melton Ross specimens may be the first published Bed VII (sample -17) to Bed F (sample -3). record of A.? spongireticulata outside Germany. Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

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Stratigraphic range/occurrence. At Melton Ross, Bed B (3II) appears to be absent but this could be due to specimen (sample -13) to Bed F (sample -5). In NW Germany, Prössl damage. Likewise, a precingular 6II plate may be damaged. A (1990) reported an Albian to Middle Turonian range for A.? second specimen with less well-developed or preserved septae spongireticulata. (Fig. 7.7) indicates that six precingular plates may usually be present. The highly distinctive morphology warrants erection Genus Canninginopsis Cookson and Eisenack, 1962 of a formal species, although it is acknowledged that doing so Type species: Canninginopsis denticulata Cookson and is unusual for just three specimens. Recovery and inspection of Eisenack, 1962 further specimens is required to fully elucidate the taxon and its generic assignment. Canninginopsis? lindseyensis sp. nov. Stratigraphic range/occurrence. At Melton Ross, Bed C (sample -11 only). Figures 6.8, 6.9, 7.7 Dinoflagellate cysts of uncertain supra-generic affinity Derivation of name. From Lindsey, a former Anglo- Saxon kingdom and current district of Lincolnshire. Dinoflagellate? type D of Ioannides 1986 Designation of holotype. Figures 6.8, 6.9.Sample MR11. Slide MR11(B). Coordinates P44/3. Location, Figures 6.13, 6.14 Melton Ross Quarry, Lincolnshire, UK. Stratum, Bed C, Flixton Member, Welton Chalk Formation. The specimen is Dimensions (27 specimens). Diameter (autophragm curated in the MPK collection of the British Geological Survey, central body): 45.7 (60.7) 75.2 µm. Keyworth, Nottingham, UK, specimen number MPK 14663. Discussion. Ioannides (1986, p. 42, pl. 25, figs 1–4, 6) Diagnosis. An areoligeracean dinoflagellate cyst posses- described comparable though slightly larger taxa from Upper sing tabular to penitabular thickenings that form the bases of Cretaceous (Santonian–Maastrichtian) deposits in Arctic thinner, entire septae. Canada (size range 70–79 µm length and 70–87 µm width; Description. Small to intermediate-sized, lenticular- 11 measured specimens). He noted that ornament varied shaped autocysts with differential development of a larger from granular to minutely verrucate/rugulate, and that, ‘in left antapical horn. A sulcal notch is present. The cyst wall is some specimens, a number of ‘slits’ have been observed c. 1 µm thick and has a smooth to slightly reticulate surface. along the autophragm. Although a weak plate attachment Tabulation is indicated by an apical archaeopyle (operculum may be suggested, no definite regular pattern has been detached) and tabular to penitabular thickenings, c. 1–2µm determined. Occasionally, six paraplates (precingular or high and 1–3 µm wide, that form the bases of thinner septae. postcingular) may be visualised’, as shown here in Figures The septae are c. 2–5 µm high and 1 µm wide, entire, smooth 6.13, 6.14. A similar but larger form (140 × 119 µm), to slightly reticulate and often exhibit some longitudinal surrounded by a kalyptra, was described from Western folding (‘creases’). Proximal thickenings/septae are adjacent Australia by Cookson and Eisenack (1971, p. 223, plate 11, (tabular) or separated by gaps of up to 4 µm (penitabular). fig. 1) as Eyrea sp. Occasional Melton Ross specimens The gonyaulacoid tabulation pattern is (operculum not possess a kalyptra, comparable to Eyrea sp., but most observed); 6II, 6c, 5–6III, ?1P, 1IIII, ?s. specimens lack an outer layer. Comparable specimens from Dimensions (length × width, without operculum). Poland were assigned to Eyrea? spp. by Dodsworth (2004b). Holotype: length 44.4 µm, width 54.1 µm. Other specimens In poorly preserved material from eastern England, it can be (two measured): length 43.0 (46.3) 49.6 µm, width 58.9 difficult to distinguish specimens of Dinoflagellate? type D (64.3) 69.6 µm. from degraded and/or broken specimens of Sentusidinium Discussion. The shape, presence of a sulcal notch and a ringnesiorum (cf. Fig. 7.20) and the granular endocysts of probable small postcingular 1III plate (Fig. 6.8) indicate an Trithyrodinium suspectum and Ginginodinium? sp. A. areoligeracean affinity (cf. Evitt 1985, text-figs 10.2, 10.6). Stratigraphic range/occurrence. At Melton Ross, local Strongly developed tabulation is consistent with the genus Bed I to Bed H. A broad Late Cretaceous range is suggested Canninginopsis. Although the type species and most other by the records of Ioannides (1986) and Cookson and accepted species often possess discontinuous ornament Eisenack (1971). elements reflecting tabulation such as spines or grana, continuous septae are present on the species Canninginopsis Acknowledgements Richard Stansfield, CEO of the Singleton Birch maastrichtiensis from the Maastrichtian of Belgium and Group, is thanked for allowing access to Melton Ross Quarry in 1997 and encouraging publication of new data. In 2019, quarry staff members Ben Hyde and Netherlands (Slimani 1994). However, the development of Dave Alliss provided an update on the sampled sites. PD undertook palynological gaps between septae, giving rise to penitabular ornament, is laboratory processing of the Melton Ross samples at the former Aberdeen office of Robertson Research International Ltd while employed there as a biostratigrapher inconsistent with Canninginopsis and warrants questionable in 1997. The company and its former management, Keith L. Marshall and Grant assignment to the genus. Penitabulation has been noted in the Heath, are thanked for providing the laboratory facilities. KLM is also thanked for permission to refer to his unpublished PhD thesis. Tim Absalom and James Quinn related genus Canningia,e.g.Canningia transitoria (Stover of Plymouth University drafted Figure 2. Jennie Houlgrave of RPS Ichron and Helby 1987, fig. 4) but its septae are coarsely perforate. prepared Figure 3 and assisted with Figure 4. Natalia Lebedeva, Klaus Prössl and Schematophora possesses entire to occasionally perforate staff at the Geological Society library assisted with gathering literature. Organic geochemistry and stable isotope work were commissioned by StrataSolve Ltd in penitabular ridges but has a spherical, non-areoligeracean 2019. TOC and Rock-Eval pyrolysis analyses were undertaken by Adam Fermor shape and lacks any tabulation in the cingulum region and Patrick Barnard of APT (UK) Ltd. Stable isotope analyses were conducted by Christopher Day, Department of Earth Sciences, Oxford University. StatoilHydro (Deflandre and Cookson 1955; Stover and Evitt 1978). On AS (now Equinor Energy AS) are thanked for permission in 2010 to publish the the holotype of C.? lindseyensis, the dorsal precingular plate CTB section from their Norwegian well 35/6-2 S. James P. Fenton and Martin Downloaded from http://pygs.lyellcollection.org/ by guest on September 24, 2021

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