Piasecki 2024: GEUS Bulletin 57. 8373. https://doi.org/10.34194/geusb.v57.8373 1 of 15 RESEARCH ARTICLE The Scriniodinium crystallinum dinoflagellate cyst zone in the Middle–Upper Oxfordian, Upper Jurassic, Ilimananngip Nunaa (Milne Land), East Greenland Stefan Piasecki* Emeritus, Section for Geobiology, Globe Institute, University of Copenhagen, Copenhagen, Denmark; Department for Geophysics and Sedimentary Basins, Geological Survey of Denmark and Greenland (GEUS), Copenhagen, Denmark Abstract The biostratigraphy of the Jurassic in East Greenland is historically based on macroscopic fossils. Stratigraphy based on palynomorphs (spores, pollen and dinoflagellate cysts) has progressed more slowly and sporadically. The Scriniodinium crystallinum dinoflagellate cyst Zone is identified in mid- dle – upper Oxfordian strata of Ilimananngip Nunaa (Milne Land), central East Greenland. The lower boundary is defined by the last occurrence of Trichodinium scarburghense in the Cardioceras tenuis- erratum ammonite Zone. The upper boundary is defined by the last occurrence of S. crystallinum in the uppermost Amoeboceras rosenkrantzi ammonite Zone. However, the subzonal division of the S. crystallinum Zone recorded in North-West Europe is not identified in Greenland. Eighteen characteristic dinoflagellate cyst events are considered stratigraphically significant and useful in East Greenland. Fifteen of these events provide an informal, detailed stratigraphical subdivision of the S. crystallinum Zone into 10 subunits. Identification of the zone is an addition to the previously defined upper Bathonian – middle Oxfordian zonation, where the uppermost palynostratigraphical event was recorded to be the last occurrence of T. scarburghense. With this study, the correlation of dinoflagellate cyst and ammonite stratigraphy in the lower and middle Oxfordian is slightly modi- fied. The S. crystallinum Zone documented here, in combination with the zonation used for the stra- tigraphy of the Blokelv-1, Rødryggen-1 and Brorson Halvø-1 cores of the Upper Jurassic to Lower Cretaceous, completes the dinoflagellate cyst stratigraphy of the marine Jurassic in East Greenland. Together with previous studies of spores and pollen in less marine units, the first complete paly- nological Jurassic stratigraphy is thus established for the Jurassic succession in East Greenland. *Correspondence: stefan.piasecki@sund. ku.dk Received: 23 Feb 2024 Revised: 06 May 2024 Accepted: 09 Jun 2024 Published: 04 Nov 2024 Keywords: Dinoflagellate cysts, stratigraphy, Upper Jurassic, Oxfordian– Kimmeridgian, East Greenland GEUS Bulletin (eISSN: 2597-2154) is an open access, peer-reviewed journal published by the Geological Survey of Denmark and Greenland (GEUS). This article is distributed under a CC-BY 4.0 licence, permitting free redistribution, and reproduction for any purpose, even commercial, provided proper citation of the original work. Author(s) retain copyright. Edited by: Karen Dybkjær (GEUS, Denmark) Reviewers: James B. Riding (British Geological Survey, UK), Morten Smelror (Geological Survey of Norway) Funding: See page 14 Competing interests: See page 14 Additional files: None 1 Introduction Jurassic biostratigraphy is historically based mainly on macroscopic fossils, especially on ammonites but with significant contributions from other fos- sil groups. The Jurassic ammonite stratigraphy became the standard strati- graphical zonation, and the ammonite zones were applied as chronozones (e.g. Callomon 1984, 1993). Integration and correlation of microscopic fossil stratigraphy with ammonite stratigraphy developed and accelerated in the 1950s–1960s, following increasing demand of stratigraphical frameworks from expanding, worldwide industrial drilling programs primarily for offshore energy exploration. Studies of dinoflagellate cysts and their stratigraphical occurrences were established relatively early for the Jurassic in Europe but with somewhat slower progress in the northern Atlantic region. On Jameson Land, East Greenland (Fig. 1), Jurassic sedimentary samples for dinoflagellate cyst stratigraphy were collected systematically from beds with ammonites by Tove Birkelund in the 1970s and made accessible to students and industry palynologists. On Ilimananngip Nunaa (Milne Land) in 1977, samples for palynological studies were collected mainly by this author, with contributions from members https://doi.org/10.34194/geusb.v57.8373 https://orcid.org/0000-0002-7846-859X mailto:stefan.piasecki@sund.ku.dk mailto:stefan.piasecki@sund.ku.dk https://creativecommons.org/licenses/by/4.0/deed.ast Piasecki 2024: GEUS Bulletin 57. 8373. https://doi.org/10.34194/geusb.v57.8373 2 of 15 GEUSBULLETIN.ORG of the field team: T. Birkelund, John H. Callomon (ammo- nites), Claus Heinberg and Franz Fürsich (molluscs) and Lars Stemmerik (sedimentology). Successions at 52 local- ities were sedimentologically logged, collected for fossils and sampled for palynology, coordinated by three field teams. The studied localities were numbered 1–52 (Pias- ecki 1980, fig. 1; Birkelund & Callomon 1985, fig. 1). Locality 39 east of Visdal on Milne Land (Fig. 1C) was measured in 1977, and a series of samples were marked by Birkelund & Callomon (1985, figs 1 and 3) and collected (Piasecki 1980, fig. 34). The succession belongs to the Kos- mocerasdal, Aldinger Elv and Bays Elv Members of the Kap Leslie Formation (Fig. 2). Five faunal horizons of ammonites were identified and referred to the Milne Land ammonite faunal horizons M 12, M 13 and M 14 (Fig. 3; Callomon & Birkelund 1980; Birkelund & Callomon 1985). These faunas represent the Boreal faunal province (Amoeboceras regu- lare and Amoeboceras rosenkrantzi ammonite zones) and the Sub-Boreal province (Pictonia baylei ammonite Zone) of the upper Oxfordian to the lowermost Kimmeridgian (Fig. 3). Such a complete ammonite zonation has not been doc- umented in any other exposure on Milne Land or Jameson Land, though faunal horizons M 13 and M 14 were tenta- tively identified in the fine-grained Hareelv Formation on Jameson Land (Callomon & Birkelund 1980, fig. 3). Faunal horizons are not recorded in the lower part of the succession at locality 39 of Kosmocerasdal Member (Fig. 2). Comparison with other exposures in eastern Milne Land indicates that this part of Kosmocerasdal Member pre- sumably correlates with the upper Oxfordian, uppermost Amoeboceras glosense – Amoeboceras serratum ammonite zones. Faunal horizon M 11, A. serratum ammonite Zone, is only recognised in coarse-grained, sandstone exposures of Aldinger Elv Member (Fürsich & Heinberg 1983), where no samples were collected for dinoflagellate cysts. Locality 39 displays a condensed and continuous upper Oxfordian succession, well dated by ammonites, and is probably the only complete section in central East Greenland. The sediment is mostly fine-grained sandstone with concretions and little potential for palynological content. Nevertheless, dinoflagellate cyst assemblages have been recovered from all samples. For this study, palynological sample materials from ammonite bearing beds and horizons were collected for direct comparison of palynology and ammonite stratigraphy in the Oxfordian from a composite section from Kosmocerasdal (locality 2), Nordøstelv (locality 3), ‘Ilovaiskii’ Dal (locality 4) and ‘Hystrix’ Dal (locality 5) – all below Aldinger Elv Member in the north-eastern expo- sures of Jurassic sediments on Milne Land (Figs 1 and 4). This composite succession is integrated with that of locality 39 and extends the Jurassic succession in East Greenland downwards into the existing dinoflagellate cyst stratigraphy of Smelror (1988). 2 Material and methods All material was originally sampled in the field campaign of 1977 from the Kap Leslie Formation at localities 2–6 and 39 (locations in Fig. 1). The Kap Leslie Formation is dom- inated by conglomerates, sand and muddy sandstone. Only the Gråkløft Member of the Kap Leslie Formation comprises laminated dark mudstones (Figs 2 and 4). The stratigraphical range chart presented here (Fig. 5) is a combination of two successions. The lower part is from localities 2–5 (shown at reduced scale in Fig. 5 and true scale in Fig. 4). The upper part is from locality 39 (illustrated at true scale in Fig. 5). The Bays Elv Member above the Aldinger Elv Member in Cardioceraskløft (local- ity 6) has no confidently identified ammonite faunal hori- zons but correlates with the upper succession of locality 39 (Fig. 4; Piasecki 1980; Birkelund & Callomon 1985). Stratigraphical events from the Cardioceraskløft succes- sion (Fig. 4) are compared here with data from locality 39, to support the new palynological zone for the upper Oxfordian but are not included in the range chart in Fig. 5. The ammonites were generally recovered in carbon- ate cemented sandstone beds or calcareous concretions and were subsequently referred to ammonite faunal horizons, M 1–M 15, by Callomon & Birkelund (1980; e.g. M 2 is the second faunal horizon on Milne Land). The faunal horizons are referred to ammonite zones (Fig. 3). The ammonite stratigraphy applied here follows the East Greenland tradition (e.g. Sykes & Surlyk 1976; Callo- mon 1993) of combined Boreal and Sub-Boreal zonation (Fig. 3) and likewise the concept of considering ammo- nite zones as chronozones. Here, however, ammonite zones are consequently referred to as biozones. The basis of an ammonite zone is indicated at the lowermost occurrence of the index species in a faunal horizon, and the top of the zone is defined by the appearance of the next index species. Compared to earlier interpretations, the Cardioceras densiplicatum and Cardioceras tenuiserra- tum ammonite zones are consequently reduced slightly in thickness and sample density, whereas the thickness of A. glosense ammonite Zone is expanded. The sample material was processed by standard meth- ods. The crushed samples were prepared with acid (HCl, HF and HNO3) to remove carbonate and silica (clay, silt and sand) from the samples. Organic matter is resistant to the acid, and the remains contained abundant terres- trial organic material, especially brown and black woody material. The separation method developed by Hansen & Gudmundsson (1979) was applied to the organic residue and successfully removed most of the abundant woody material and improved the recovery of identifiable dino- flagellate cysts significantly. The remaining organic residue was mounted in glycerine-gelatine on preparation glasses for visual analysis using a standard light microscope. Although the slides were prepared in the 1970s, most are https://doi.org/10.34194/geusb.v57.8373 http://www.geusbulletin.org/ Piasecki 2024: GEUS Bulletin 57. 8373. https://doi.org/10.34194/geusb.v57.8373 3 of 15 GEUSBULLETIN.ORG Volquart Boon Coast Crystalline basement Kap Leslie Fm Charcot Bugt FmHartz Fjeld Fm Paleogene basalt Hesteelv Fm Raukelv Fm Hareelv Fm Pelion Fm Neill Klinter Gp Kap Stewart Gp 23°W24°W 70°30ʹN 25 km Jameson Land B Blokelv-1 18°W 16°W 76°N 72°N 70°N 22°W 20°W SAF PDMF DF LLE LLE Cretaceous Jurassic Triassic Permian Main faults Stauning Alper Fault Post-Devonian Main Fault Dombjerg Fault Liverpool Land Escarpment Locality Greenland Ilim ananngip Nunaa (M ilne Land) Gåseland Traill Ø Geographical Society Ø Hold with Hope Clavering Ø Th.Thomsen Land Kuhn Ø Hochstetter Forland Store Koldewey Germania Land A Kulhøj Wollaston Forland P D M F S A F D F Jameson Land Kangerluk Kong Oscar Liverpool Land Kangersaajiva (Hurry Inlet) 50 km 26°W 22°W24°W28°W 26°W 24°W Hall Bredning 74°N BC A Brorson Halvø -1 Rødryggen-1 25°20ʹW 70°50ʹN 20 km 25°40ʹW C 2 3 4 5 6 39 ! Kangertittivaq (Scoresby Sund) Ilimananngip Nunaa (Milne Land) K an ge rs aa jiv a (H ur ry In le t) Quaternary Ice Sea Rivers Faults Fig. 1 Map of the study area. A: Geological map of East Greenland (modified from Surlyk et al. 2021) with locations of the Rødryggen-1 and Brorson Halvø-1 drilling sites. Inset: maps of localities analysed in this study. B: Jameson Land with Blokelv-1 core and C: Ilimananngip Nunaa (Milne Land) with localities M 2, 3, 4, 5, 6 and 39 (locality numbers sensu Birkelund et al. 1984). https://doi.org/10.34194/geusb.v57.8373 http://www.geusbulletin.org/ Piasecki 2024: GEUS Bulletin 57. 8373. https://doi.org/10.34194/geusb.v57.8373 4 of 15 GEUSBULLETIN.ORG still perfectly preserved, and only a few had to be restored for the present study. The dinoflagellate cyst taxonomy follows Fensome et al. (2019) and Riding et al. (2022) with respect to the former Gonyaulacysta jurassica group. 2.1 History of dinoflagellate cyst stratigraphy in East Greenland Overall, the Middle – Upper Jurassic, Boreal or Sub-Boreal ammonite stratigraphy in East Greenland is well documented on Milne Land (Callomon & Birkelund 1980; Birkelund et al. 1984; Birkelund & Callomon 1985), Jameson Land (Surlyk et al. 1973; Callomon et al. 2015) and in North-East Greenland (Sykes & Surlyk 1976). The studies mentioned in the follow- ing focus on Middle – Upper Jurassic dinoflagellate cysts from central East Greenland. The number of studies is limited, and only a few cover the middle – upper Oxfordian interval. Samples collected from central Jameson Land by R.C. Whatley and D.C. Brown in 1964 were prepared in the lab- oratory of University of Nottingham, UK, but were subject to a fire in the laboratory. Only parts of two preparations survived and were analysed by W.A.S. Sarjeant (1972). But the value of these data suffers from uncertainties of their stratigraphical derivation. The age of the two samples was considered Bathonian to Callovian of the Vardekløft Formation, now Vardekløft Group (Surlyk et al. 2021). The samples were collected near the locality Langryggen in central Jameson Land, probably from within the lowermost Olympen Formation (Athene and Hades Members) to Fos- silbjerget Formation interval (see Larsen & Surlyk 2003; Surlyk et al. 2021). The uppermost sample comprises Endo- scrinium luridum, Trichodinium scarburghense and Wanaea digitata and several other species that are in accordance with a latest Callovian – earliest Oxfordian age of the Quen- stedtoceras lamberti – Quenstedtoceras mariae ammonite zones. The age of the dinoflagellate cyst assemblage of the lower sample (c. 75 m lower in the section) is imprecise. The presence of Gonyaulacysta eisenackii, Rhynchodiniopsis (Gonyaulacysta) cladophora and Pareodinia prolongata as well as a more marine assemblage may indicate that the sample is from the uppermost Fossilbjerget Formation of Callovian age (see Surlyk et al. 2021). A new acritarch genus (later referred to dinoflagellate cysts) Mendicodinium (Thuledinium) groenlandicum was described by Pocock & Sarjeant (1972) based on type mate- rial from Sarjeant’s upper sample. The species is abundant in this sample, and it is known to have peak abundance in the Q. lamberti ammonite Zone (e.g. Smelror 1988), indicat- ing that the sample is from this ammonite zone, and conse- quently that both of Sarjeant’s samples are of Callovian age. A geographically and stratigraphically wide suite of 27 Jurassic samples collected by T. Birkelund on Jameson Lithostratigraphy of Jurassic to lower Cretaceous on Milne Land K ap L es lie F or m at io n Kosmocerasdal Member Aldinger Elv Member Bays Elv Member Cardioceraskløft Member Gråkløft Member Krebsedal Member Pernaryggen Member Astartedal Member Hartz Fjeld Formation Coarse-grained sand and conglomerates Sand Silty, very fine-grained sand Pinnadal Formation Charcot Bugt FormationMiddle Oxfordian to lower Bathonian Middle Volgian to middle Callovian Valanginian to middle Volgian Hauterivian Laminated, organic-rich mudstone Chronostratigraphy Fig. 2 Lithostratigraphical scheme of Jurassic to Lower Cretaceous sedi- ments on Milne Land based on Callomon & Birkelund (1980), Birkelund & Callomon (1985), Birkelund et al. (1984) and Surlyk et al. (2021). Kimmeridgian Oxfordian Callovian Lo w er M id dl e U pp er M 14 M 15 M 13 M 12 M 11 M 10 M 9 M 8 M 7 M 6 M 5 M 4 M 3 M 2 Stage Fauna horizon Ammonite zone Ammonite fauna horizons, Milne Land BorealSub-Boreal Ammonite faunal provinces: Rasenia cymodoce Pictonia baylei Amoeboceras rosenkrantzi Amoeboceras regulare Amoeboceras serratum Amoeboceras glosense Amoeboceras glosense Cardioceras tenuiserratum Cardioceras densiplicatum Cardioceras densiplicatum Cardioceras densiplicatum Cardioceras cordatum Quenstedtoceras mariae Quenstedtoceras lamberti Peltoceras athleta Fig. 3 Ammonite faunal horizons on Milne Land correlated with ammo- nite zones (Callomon & Birkelund 1980; Birkelund & Callomon 1985). Shading indicates the faunal province affiliations. https://doi.org/10.34194/geusb.v57.8373 http://www.geusbulletin.org/ Piasecki 2024: GEUS Bulletin 57. 8373. https://doi.org/10.34194/geusb.v57.8373 5 of 15 GEUSBULLETIN.ORG M 3 M 4 M 2 M 2 M 5 M 6 M 8 M 8 M 9 M 9 M 10 M 10 Locality 2 Kosmocerasdal Locality 3 Nordøstelv Locality 4 “Ilovaiskii” Dal Locality 5 “Hystrix” Dal C ha rc ot B ug t F m K ap L es lie F m / K os m oc er ad al M b K os m oc er ad al M b K os m oc er ad al M b K os m oc er ad al M b K os m oc er ad al M b A ld in ge rs E lv M b C la y S ilt S an d G ra ve l C la y S ilt S an d G ra ve l C la y S ilt S an d G ra ve l C la y S ilt S an d G ra ve l C la y S ilt S an d G ra ve l 240 230 220 210 200 190 240 250 260 270 280 290 50 40 30 20 10 0 20 30 40 50 60 20 10 – 245977-78 – 245975-76 – 245974 – 245973 – 245972 – 245969-71 – 245968 – 245967 – 245966 – 245965 – 245964 – 245963 – 245962 – 245961 – 245958-60 – 245957 – 245956 – 245955 – 245954 – 245953 – 245952 – 245951 – 245990 – 245989 – 245987-88 – 245986 – 245985 – 245984 – 245983 – 245982 – 245981 – 245980 – 234242 – 234241 – 234240 – 234239 – 234238 – 234237 – 234235 – 234236 – 234172 – 234171 – 234169-70 – 234168 – 234167 – 234166 – 234165 – 234164 – 234163 – 234162 – 234161 – 234160 – 234159 – 234158 – 234157 – 234156 – 234155 – 234154 – 234153 – 234178 – 234177 – 234176 – 234175 – 234173-74 [m] [m] [m] [m] [m] M 15 M 7 M 12 M 13 M 13 M 14 M 13 10 20 30 40 0 Locality 6 Cardioceraskløft Locality 39 E of Visdal Legend Grain size: Concretions: Pebbles Gravel Sand Silt Sediment structures: Giant-scale planar cross-bedding Large-scale planar cross-bedding Large-scale trough cross-bedding Small-scale ripple cross-bedding Lenticular bedding Planar lamination Pyrite Glauconite Basalt Lithology: Trace fossils: Fossils: Doggers Calcareous or pyritic concretions Ferro-concretions Concretionary beds of distinct horizons of concretions Wood Ammonite Belemnite Bivalve Diplocraterion Thallasinoides Chondrites Planolithes Muensteria – 245834 – 245833 – 245832 – 245831 – 245830 – 245829 – 245828 – 245827 – 245826 – 245825 – 245824 – 245823 – 245822 – 245818 – 245817 – 245816 – 234219 – 234220 – 234221 – 234224 – 234225 – 234227 – 234228 – 234229 – 234230 – 234231 – 234232 C la y S ilt S an d G ra ve l C la y S ilt S an d G ra ve l 100 90 80 70 [m] [m] A .E . M b B ay s E lv M em be r C . M b C ha rc ot B ug t F m K ap L es lie F or m at io n V is da l M b K os m oc er as da l M b A .E . M b B ay s E lv M em be r Fig. 4 Measured and sampled sedimentary successions from Milne Land with ammonite faunal horizons (e.g. M 14) and palynological samples (e.g. GGU245951) modified from Piasecki (1980). The locality numbers are from Piasecki (1980, fig.3) and Birkelund & Callomon (1985, fig. 2). The sedimentary succession from localities 2–5 shows the complete Kosmocerasdal Member, Kap Leslie Formation. Sedimentary logs from locality 6, Cardioceraskløft, and locality 39, east of Visdal, are correlated by the upper boundary of Aldinger Elv Member and the basis of Bays Elv Member. https://doi.org/10.34194/geusb.v57.8373 http://www.geusbulletin.org/ Piasecki 2024: GEUS Bulletin 57. 8373. https://doi.org/10.34194/geusb.v57.8373 6 of 15 GEUSBULLETIN.ORG Land were published by Fensome (1979). This compre- hensive, taxonomic and excellent pioneering work in East Greenland included four samples presumed to be of upper Oxfordian – lower Kimmeridgian from south- ern and middle Jameson Land. These samples could be expected to overlap stratigraphically with the material from middle – upper Oxfordian to lowermost Kimmerid- gian of the present study. However, the proposed age of three of these samples was not based on correlation with ammonite zonation but on their presumed litho- stratigraphical affiliation to the Hareelv Formation. The presence of Wanaea fimbriata, W. digitata, Rigaudella aemula and T. scarburghense in these samples (Fensome 1979) suggests an earliest Oxfordian age. These sam- ples are therefore stratigraphically comparable with the lower Olympen Formation, especially the dark shales of the Hades Member (see Larsen & Surlyk 2003; Surlyk et al. 2021). Two of the samples were collected close to Sarjeant’s locality in central Jameson Land. The fourth sample was referred to the ‘?decipia ammonite zone, lower Kimmeridgian, but this zone is classed as upper Oxfordian in the stratigraphical scheme (Fensome 1979, Table 1 after Surlyk et al. 1973). The sample is assigned to the middle – upper Oxfordian based on the dinofla- gellate cyst content, and the species are also common in the assemblages of the present study. Distinction of lower Oxfordian black shales of the Olympen Formation from the upper Oxfordian Hareelv Formation is prob- lematic in the south to mid-Jameson Land Basin, where the shales are deposited successively. The two dark shale units cannot be distinguished lithologically from each other but only by biostratigraphy (Finn Surlyk, pers. comm. 2023). Piasecki (1980) analysed dinoflagellate cysts from Callovian to Middle Volgian on Milne Land. The cor- relation of dinoflagellate cyst stratigraphy with ammo- nite zones is revised slightly herein for a few of these samples (Fig. 4). The results have been published in various reports and used for analysis of sections and core-drillings during fieldwork in East to North Green- land from 1982 to 2012 (e.g. the core-drillings Blokelv-1, Rødryggen-1 and Brorson Halvø-1; Alsen & Piasecki 2018; Bjerager et al. 2018; Alsen et al. 2023). Poulsen (1985) analysed a high-resolution series of samples for dinoflagellate cysts across the boundary of the Fossilbjerget – Hareelv Formations at Ugleelv. The samples were collected by S. Piasecki, and scat- tered samples from the overlying Hareelv Formation were sampled by T. Birkelund and C. Heinberg in Ugleelv, Jameson Land. One ammonite faunal horizon M 9, Amoeboceras ilovaiskii Subzone, lower A. glosense ammonite Zone is correlated with the dinoflagellate cyst stratigraphy (faunal horizon J 49 on Jameson Land, Callomon 1993). As mentioned earlier, the lower black shales assigned to the Hareelv Formation should have been classified as the Olympen Formation (see also Callomon 1993, fig. 2). Upper Bathonian to middle Oxfordian dinoflagel- late cyst assemblages from Fossilbjerget and Olympen localities on Jameson Land and from Kosmocerasdal on Milne Land were reported by Smelror (1988) based on samples collected by T. Birkelund, J.H. Callomon and S.  Piasecki. The samples were correlated with ammo- nite stratigraphy, and a dinoflagellate cyst zonation was established up to the middle Oxfordian, C. densiplicatum ammonite Zone at the last appearance of the dinoflagel- late cyst T. scarburghense. Gen. et sp. Nidarocysta jubilaea was described by Mon- teil (1966) from upper Oxfordian – lower Kimmeridgian core material in Norway and East Greenland. The East Greenland sample material is from Sjællandselv-3 core 303116 in Jameson Land (Bjerager et al. 2018). In a study of stacked sandstone bodies from the Batho- nian to uppermost Oxfordian on Milne Land and Jameson Land, Larsen et al. (2003) applied integrated ammonite and dinoflagellate cyst stratigraphy, the uppermost part of which overlaps with the present study. Kelly et al. (2015) applied Jurassic biostratigraphy from North-West Europe to East Greenland without much documentation. Alsen & Piasecki (2018) reported integrated ammo- nite and dinoflagellate cyst from the Jurassic Blokelv-1 core on Jameson Land dated to the Hareelv Formation. Relatively few stratigraphical events of dinoflagellate cysts were assigned to the upper Oxfordian – lowermost Kimmeridgian interval. Meanwhile, Alsen et al. (2023) reported integrated ammonite and dinoflagellate cyst stratigraphy in the Upper Jurassic – Lower Cretaceous cores of the Rødryggen-1 and Brorson Halvø-1 wells drilled in Wollaston Forland (locations in Fig. 1). How- ever, these wells did not reach the Oxfordian – lower- most Kimmeridgian. 2.2 Biozonation Palynological analysis of the middle to upper Oxfordian sedimentary succession on Milne Land, East Greenland, shows a relatively poor and low diversity dinoflagellate cyst assemblage (Fig. 5). However, the assemblage can be referred to the G. jurassica – S. crystallinum Zone (Gj/Sc) of North-West Europe (Woollam & Riding 1983; amended by Riding & Thomas 1988, 1992). The zone is defined from the last occurrence of T. scarburghense (formerly Acanthaulax senta) to the last occurrence of S. crystallinum and is correlated with the base of C. tenuis- erratum ammonite Zone to the P. baylei ammonite Zone, middle Oxfordian to lowermost Kimmeridgian in North- West Europe. https://doi.org/10.34194/geusb.v57.8373 http://www.geusbulletin.org/ Piasecki 2024: GEUS Bulletin 57. 8373. https://doi.org/10.34194/geusb.v57.8373 7 of 15 GEUSBULLETIN.ORG In East Greenland, the last occurrence of T. scarbur- ghense is also recorded in the lower C. tenuiserratum ammonite Zone in Kosmoceras Dal, Milne Land, locality 2 (Piasecki 1980). The last occurrence of S. crystallinum is recorded in the top of A. rosenkrantzi ammonite Zone, locality 39, East of Visdal (Figs 2–4). The S. crystallinum Zone extends the zonation of Smelror (1988) to the base of the Kimmeridgian. The zone name was simplified to S. crystallinum Zone (Riding & Thomas 1988), and both lower and upper boundaries were subsequently redefined based on other recorded events. The position of the last occur- rence of S. crystallinum varies slightly in later reports (Riding & Thomas 1988, 1992, 1997) from A. rosenkrantzi ammonite Zone to P. baylei ammonite Zone followed by rare scattered, higher stratigraphic occurrences. The last occurrence of S. crystallinum in the P. baylei ammo- nite Zone is maintained by Poulsen & Riding (2003). Woollam & Riding (1983) divided the zone into three subzones. The lower subzone ‘a’ is defined from the last occurrence of T. scharburghense to the last occurrence of Compositosphaeridium polonicum and is well recognised in East Greenland (Fig. 5). The two stratigraphically higher subzones ‘b’ and ‘c’ are not recognised within East Greenland stratigraphy. Poulsen & Riding (2003) applied five subzones, named DSJ23–27, to the S. crystallinum Zone, including part of the upper T. scarburghense Zone (where DSJ refers to dinoflagellate cysts, Sub-Boreal zonation and Jurassic). The five subzones are not readily recognised in East Greenland partly due to the absence or rarity of the most indicative species. Also, the upper- most subzone DSJ27 is not recognised in East Greenland due to the absence of S. crystallinum in the lowermost Kimmeridgian, P. baylei ammonite Zone (Figs 5 and  6). The dinoflagellate cyst assemblage in the P. baylei ammonite Zone is thus referred to the E. luridum Zone (Woollam & Riding 1983; Nøhr-Hansen 1986) although the nominate dinoflagellate cyst itself is not abundant in East Greenland (Fig. 6). In contrast, the middle Oxford- ian to lowermost Kimmeridgian dinoflagellate cyst zone interval, named JZ32–JZ38 in the North Atlantic (where JZ refers to Jurassic Zone, sensu Bailey 2023), is based on 71 p 23 Amoeboceras glosense/serratum El ev at io n 25 20 15 10 5 0 –5 –10 –15 –20 –25 Li th os tr at ig ra ph y (* 1 A ld in ge r E lv M b) H al l B re dn in g G ro up (L oc al ity M 3 9) H al l B re dn in g G ro up (L oc al iti es M 2 –5 ) G ro up K ap L es lie F or m at io n Fo rm at io n B ay s E lv M em be r *1 K os m oc er es da l M em be r M em be r C hr on os tr at ig ra ph y (* 2 K im m er id gi an ) *2 U pp er O xf or di an M id . O xf od ia n pa rs . Su bs ta ge U pp er J ur as si c A m m on ite e ve nt s 33.00 32.00 30.00 24.00 17.00 –7.50 –15.50 –17.25 –25.00 A m m on ite z on at io n 33.00 24.00 17.00 0.00 7.50 17.25 25.50 S .c ry st al lin um Z on e (s en su R id in g & T ho m as 1 98 8) S . c ry st al lin um Z on e D in of la ge lla te c ys t e ve nt s 32.00 Top of S. crystallinum 27.00 Base of E. irregulare 13.00 1.00 –2.00 –3.00 –9.50 –14.00 –14.50 Base of P. borealis Base of H. orbifera Top of S. redcliffense Base of D. jurassicum Top of K. stegasta Base of D. minutum Top of C. polonicum Base of L. subtile Base of A. staffinensis Base of S. valensii Base of S. inritibile Top of R. aemulum–16.50 Top of C. cerastes –22.50 Top of T. scarburghense Sa m pl es (G G U s am pl e nu m be rs ) B ar re n Stratigraphic range In situ, reworked, '?' occurrences 1 B ar ba ta cy st a pe lio ne ns is 2 B at ia ca sp ha er a la ev ig at a 3 C hy tro ei sp ha er id ia c er as te s 4 C om po si to sp ha er id iu m p ol on ic um 5 D is si lio di ni um h oc ne ra tu m 6 E nd os cr in iu m g al er itu m 7 E nd os cr in iu m lu rid um 8 G on ya ul ac ys ta ju ra ss ic a 9 K al yp te a st eg as ta 10 N an no ce ra to ps is p el lu ci da 11 P ar eo di ni a ce ra to ph or a 12 R hy nc ho di ni op si s cl ad op ho ra 13 R ig au de lla a em ul um 14 R ig au de lla fi la m en to sa 15 S cr in io di ni um c ry st al lin um 16 S irm io di ni um g ro ss ii 17 S ys te m at op ho ra s pp . 18 Tr ic ho di ni um s ca rb ur gh en se 19 Tu bo tu be re lla a pa te la 20 Va le ns ie lla d ic ty di a 21 A to po di ni um h ar om en se 22 S te ph an el yt ro n sc ar bu rg he ns e 23 W re vi tti a? h el ic oi de a 24 E sc ha ris ph ae rid ia p oc oc ki i 25 M en di co di ni um g ro en la nd ic um 26 Fr om ea s pp . 27 P ar eo di ni a ha lo sa 28 Le pt od in iu m m ira bi le 29 Le pt od in iu m s ub til e 30 M ei ou ro go ny au la x pl an os ep ta ta 31 A m bo no sp ha er a st af fin en si s 32 S cr in io di ni um in rit ib ile 33 S te ph an el yt ro n ca yt on en se 34 S ys te m at op ho ra v al en si i 35 B ar ba ta cy st a pi lo sa 36 Tu bo tu be re lla e ge m en ii 37 P ar eo di ni a ce ra to ph or a sc op ae a 38 C rib ro pe rid in iu m g ra nu lig er um 39 D in go di ni um m in ut um 40 G on ya ul ac ys ta a de ct a 41 K al yp te a di ce ra s 42 P ro lix os ph ae rid iu m g ra nu lo su m 43 S te ph an el yt ro n re dc lif fe ns e 44 Ta en io ph or a iu nc tis pi na 45 B at ia ca sp ha er a pi lo su m 46 D in go di ni um ju ra ss ic um 47 D in go di ni um tu be ro su m 48 E pi pl os ph ae ra c f. sa tu rn al is 49 B at ia ca sp ha er a sp p. 50 E nd os cr in iu m s pp . 51 G lo ss od in iu m d im or ph um 52 Li es be rg ia a ff. li es be rg en si s 53 M en di co di ni um s pp . 54 P ar eo di ni a sp p. 55 P ilo si di ni um m yr ia tri ch um 56 S irm io di ni op si s or bi s 57 S ys te m at op ho ra a re ol at a 58 G on ya ul ac ys ta d ua lis 59 H ys tri ch os ph ae rin a or bi fe ra 60 P ar ag on ya ul ac ys ta b or ea lis 61 Va le ns ie lla s pp . 62 C hl am yd op ho re lla s pp . 63 C rib ro pe rid in iu m s pp . 64 P ilo si di ni um s p. D F en so m e 19 79 65 K or ys to cy st a pa ch yd er m a 66 S en tu si di ni um s pp . 67 E nd os cr in iu m ir re gu la re 68 E pi pl os ph ae ra g oc ht ii 69 E pi pl os ph ae ra b ire tic ul at a 70 Va le ns ie lla o vu lu m P an da di ni um s in os um 31 A m bo no sp ha er a st af fin en si s 21 A to po di ni um h ar om en se 1 B ar ba ta cy st a pe lio ne ns is 35 B ar ba ta cy st a pi lo sa 2 B at ia ca sp ha er a la ev ig at a 45 B at ia ca sp ha er a pi lo su m 49 B at ia ca sp ha er a sp p. 62 C hl am yd op ho re lla s pp . 3 C hy tro ei sp ha er id ia c er as te s 4 C om po si to sp ha er id iu m p ol on ic um 38 C rib ro pe rid in iu m g ra nu lig er um 63 C rib ro pe rid in iu m s pp . 46 D in go di ni um ju ra ss ic um 39 D in go di ni um m in ut um 47 D in go di ni um tu be ro su m 5 D is si lio di ni um h oc ne ra tu m 6 E nd os cr in iu m g al er itu m 67 E nd os cr in iu m ir re gu la re 7 E nd os cr in iu m lu rid um 50 E nd os cr in iu m s pp . 69 E pi pl os ph ae ra b ire tic ul at a 68 E pi pl os ph ae ra g oc ht ii 48 E pi pl os ph ae ra c f. sa tu rn al is 24 E sc ha ris ph ae rid ia p oc oc ki i 26 Fr om ea s pp . 51 G lo ss od in iu m d im or ph um 40 G on ya ul ac ys ta a de ct a 58 G on ya ul ac ys ta d ua lis 8 G on ya ul ac ys ta ju ra ss ic a 59 H ys tri ch os ph ae rin a or bi fe ra 41 K al yp te a di ce ra s 9 K al yp te a st eg as ta 65 K or ys to cy st a pa ch yd er m a 28 Le pt od in iu m m ira bi le 29 Le pt od in iu m s ub til e 52 Li es be rg ia a ff. li es be rg en si s 30 M ei ou ro go ny au la x pl an os ep ta ta 25 M en di co di ni um g ro en la nd ic um 53 M en di co di ni um s pp . 10 N an no ce ra to ps is p el lu ci da 71 P an da di ni um s pi no su m 60 P ar ag on ya ul ac ys ta b or ea lis 11 P ar eo di ni a ce ra to ph or a 37 P ar eo di ni a ce ra to ph or a sc op ae a 27 P ar eo di ni a ha lo sa 54 P ar eo di ni a sp p. 55 P ilo si di ni um m yr ia tri ch um 64 P ilo si di ni um s p. D F en so m e 19 79 42 P ro lix os ph ae rid iu m g ra nu lo su m 12 R hy nc ho di ni op si s cl ad op ho ra 13 R ig au de lla a em ul a 14 R ig au de lla fi la m en to sa 15 S cr in io di ni um c ry st al lin um 32 S cr in io di ni um in rit ib ile 66 S en tu si di ni um s pp . 56 S irm io di ni op si s or bi s 16 S irm io di ni um g ro ss ii 33 S te ph an el yt ro n ca yt on en se 43 S te ph an el yt ro n re dc lif fe ns e 22 S te ph an el yt ro n sc ar bu rg he ns e 57 S ys te m at op ho ra a re ol at a 17 S ys te m at op ho ra s pp . 34 S ys te m at op ho ra v al en si i 44 Ta en io ph or a iu nc tis pi na 18 Tr ic ho di ni um s ca rb ur gh en se 19 Tu bo tu be re lla a pa te la 36 Tu bo tu be re lla e ge m en ii 20 Va le ns ie lla d ic ty di a 70 Va le ns ie lla o vu lu m 61 Va le ns ie lla s pp . W re vi tti a? h el ic oi de a 234219-TB12 ? 234220-TB11 R ? 234221-10/A 234222-TB/ 10B 234224-TB9 ? 234223-TB10/C 234225-TB8A ? ? 234226-TB8/B ? 234227-TB7 234228-TB6 ? ? 234229-TB4 R ? ? 234230-TB3 234231-TB2 ? 234232-TB1 234177 ? 234176 234175 ? 234171 ? ?234168 234167 ? 234166 ? 234165 234164 234163 234162 234160 ? 234159 R 234155 ? ? ? 234154 ? 234242 234241 ? 234239 234238 Dinoflagellate cysts 30 S er ie s Pictonia baylei Amoeboceras rosenkrantzi Amoeboceras rosenkrantzi Amoeboceras rosenkrantzi Amoeboceras regulare Amoeboceras glosense Amoeboceras ilovaiskii Cardioceras tenuiserratum A. rosenkrantzi Zone P. baylei Zone A. regulare Zone A. serratum – Upper A. glosense Zones Upper A. glosense Zone A. glosense Zone / A. ilovaiskii subzone C. tenuiserratum Zone Top of G. adecta Fig. 5 Dinoflagellate cyst range-chart based on data from a composite succession of Kosmocerasdal Member to Bays Elv Member, Kap Leslie Forma- tion. The range-chart is combined from successions at localities 2–5 and 39. To fit to the page, the composite succession of Kosmocerasdal Member is reduced 4 times in thickness and arranged from 0 to –25 m. The succession from locality 39 is shown to scale and spans 34 m from the basis of Kosmocerasdal Member to the top of Bays Elv Member. Abbreviations: Mid.: middle. *1: Aldinger Elv Mb. *2: Kimmeridgian. Dinoflagellate cyst names in Figs 5–7. https://doi.org/10.34194/geusb.v57.8373 http://www.geusbulletin.org/ Piasecki 2024: GEUS Bulletin 57. 8373. https://doi.org/10.34194/geusb.v57.8373 8 of 15 GEUSBULLETIN.ORG A B C D E F G H I J K M N O P 25 µm Q R L Fig. 6 Stratigraphically significant dinoflagellate cysts from the middle to upper Oxfordian S. crystallinum Zone in Milne Land, from locality 39, east of Visdal, and localities 2 (Kosmoceras Dal), 3 (Nordøstelv) and 4 (‘Hystrix’ Dal), eastern Milne Land (locations in Fig. 1). The illustrated specimens are referred to locality numbers, GGU sample number, slide number and England Finder coordinates. The illustrated specimens are marked with a red circle on the original slides. Magnification is x400 as indicated by a 25 µm scalebar in panel A that applies to all figures. A: Scriniodinium crystallinum, locality 39, sample GGU234229, slide 7, E.F. U35/2. B: Scriniodinium crystallinum, locality 39, sample GGU234229, slide 7, E.F. P25/2. C: Trichodinium scarburghense, locality 2, sample GGU234235, slide 4, E.F. K29/4. D: Trichodinium scarburghense, locality 2, sample GGU234235, slide 4, T34/3. E, F: Atopodinium haromense, high and low focus, locality 3, Figure 6 continued on next page https://doi.org/10.34194/geusb.v57.8373 http://www.geusbulletin.org/ Piasecki 2024: GEUS Bulletin 57. 8373. https://doi.org/10.34194/geusb.v57.8373 9 of 15 GEUSBULLETIN.ORG Figure 6 continued sample GGU234242, slide 8, P49/2. G: Chytroeisphaeridia cerastes, locality 2, sample GGU234155, slide 7, E.F. J26. H: Chytroeisphaeridia cerastes, locality 2, sam- ple GGU234155, slide 7, E.F. K52/3. I: Rigaudella aemula, locality 2, sample GGU234240, slide 6, E.F. H51. J: Ambonosphaera staffinensis, locality 39, sample GGU234227, slide 7, E.F. O26. K: Ambonosphaera staffinensis, locality 39, sample GGU234223, slide 7, E.F. U53/2. L: Systematophora valensii, locality 39, sample GGU234230, slide 3, E.F. U48/1. M, N: Leptodinium subtile, high and low focus, locality 39, sample GGU234219, slide 3, P53/2. O: Scriniodinium inritibile, locality 39, sample GGU 234230, slide 7, E.F. R51. P: Scriniodinium inritibile, locality 39, sample GGU234220, slide 7, E.F. N28/1. Q: Compositosphaeridium polonicum, locality 4, sample GGU234159, slide 8, E.F. K36/3. R: Compositosphaeridium polonicum, locality 2, sample GGU234239, slide 4, E.F. H46/m4. events with good correlation to events in the S. crystal- linum Zone in East Greenland. Some events are based on informally identified species that are not identified in East Greenland. The Jurassic dinoflagellate cyst stratigraphy of the cir- cum Arctic region (Bujak et al. 2022) adopted the stratig- raphy for lower Oxfordian of East Greenland of Smelror (1988) and reported no data for the middle and upper Oxfordian. To preserve a clear and practical definition of the S. crystallinum Zone in East Greenland, the older definition of the zonal boundaries (Woollam & Riding 1983) is maintained here. This also provides a simple extension of the preceeding dinoflagellate biostratigra- phy of Smelror (1988; Fig. 6). Dinoflagellate cyst events of the S. crystallinum Zone were recognised in two other Milne Land localities in the northern Visdal region (Larsen et al. 2003, their fig. 1, localities 5, 8 and 12) but were not discussed further in that study. The S. crystallinum Zone is also recognisable in the Blokelv-1 core on Jameson Land based on the last occurrence of T. scarburghense to the last occurrence of S. crystallinum (Alsen & Piasecki 2018, fig. 8). The upper part of the zone is also identified in the eastern slope of Tværdal, Geographical Society Ø, in a sandy succession, which is now correlated with the A. regulare – A. rosenk- rantzi ammonite zones (Surlyk et al. 2023). The S. crys- tallinum Zone is commonly recognised in the Oxfordian in both published (Piasecki et al. 2004; Piasecki & Stem- merik 2004) and unpublished materials from the Hold with Hope and Wollaston Forland regions but becomes uncertain in more northerly successions from Store Koldewey to Peary Land, North Greenland (S. Piasecki, unpublished data). Smelror (2021) analysed palynological material from three boreholes in the Ramså Basin, Andøya, Norway. Part of the upper Bonteigen Member, Ramså Formation, is referred to the P. baylei Chronozone, lowermost Kim- meridgian, based on dinoflagellate cysts. No Oxfordian succession is recorded below this. Several dinoflagel- late cyst species in the three lowermost sedimentary samples range from the upper Oxfordian into the low- ermost Kimmeridgian in East Greenland. However, cor- related with data in the present paper, the presence of Dingodinium minutum supports Smelror’s stratigraphical interpretation of these strata as lowermost Kimmerid- gian, as this species occurs no higher than the P. baylei ammonite Zone in East Greenland. 3 Results The dinoflagellate cyst assemblage is relatively poor or limited in all samples from the succession at locali- ties 2–5 and 39 (Fig. 4). This is partly due to low organic content in the sandy lithology, but, in general, reflects the low abundance and diversity in most of the mid- to upper Oxfordian interval in East Greenland. A typical succession commonly contains at least some samples with a few common species. In decreasing abundance, these are G. jurassica, R. cladophora, Sirmiodinium grossii, Systematophora spp., Taeniophora iunctispina and Cribro- peridinium spp. Ten stratigraphical units based on dinoflagellate cyst events within the S. crystallinum Zone on Milne Land are identified in the dinoflagellate cyst range chart (Fig. 5). Here, the focus is on describing correlative events instead of defining subzones that become less useful north and south of the Jameson Land Basin. Specimens mentioned in the following are illustrated in Figs 6 and 7. The lowest occurrence of the index species of the S. crystallinum Zone (Fig. 6A–B) occurs far below the zone itself. It is recorded in the Peltoceras athleta ammonite Zone, upper Callovian, in Kosmocerasdal (locality 2, Pia- secki 1980) as well as in the P. athleta ammonite zone in North-West Europe (Riding & Thomas 1992). The highest occurrence of T. scarburghense (Figs 5 and 6C–D) defines the lower boundary of the S. crystallinum Zone in the lower C. tenuiserratum ammonite Zone, in Kos- mocerasdal (locality 2, Piasecki 1980). The lowest occur- rences of Glossodinium dimorphum and Scriniodinium inritibile were implemented by Poulsen & Riding (2003) into the definition of the basal boundary of the S. crys- tallinum Zone as lower than the highest occurrence of T. scarburghense in North-West Europe. However, G. dimor- phum is very rare, and like S. inritibile, it appears in the A. glosense ammonite Zone in East Greenland. Atopodinium haromense (Fig. 6E–F) with vague morphological charac- teristics occurs rarely in the lowermost S. crystallinum https://doi.org/10.34194/geusb.v57.8373 http://www.geusbulletin.org/ Piasecki 2024: GEUS Bulletin 57. 8373. https://doi.org/10.34194/geusb.v57.8373 10 of 15 GEUSBULLETIN.ORG B C D E F G H I J K M N O 25 µm A 25 µm P S RQ L T U V 25 µm Fig. 7 Stratigraphically significant dinoflagellate cysts from the middle to upper Oxfordian in Milne Land from locality 39, Kosmoceras Dal, east of Vis- dal, and localities 2 and 6, Cardioceraskløft, in eastern Milne Land (locations in Fig. 1). The illustrated specimens are referred to locality numbers, GGU Figure 7 continued on next page https://doi.org/10.34194/geusb.v57.8373 http://www.geusbulletin.org/ Piasecki 2024: GEUS Bulletin 57. 8373. https://doi.org/10.34194/geusb.v57.8373 11 of 15 GEUSBULLETIN.ORG Zone but becomes more morphologically characteristic upwards. Smelror (1988) refers the Oxfordian Atopodin- ium species with no Atopodinium prostatum characters to morphological variation of an A. prostatum-complex, whereas Riding & Thomas (1997) record A. haromense from the basal middle Oxfordian and upwards. Chytroeisphaeridia cerastes (Fig. 6G–H) occurs with certainty up to the lower A. glosense ammonite Zone and the A. ilovaiskii Subzone. Morphologically similar speci- mens occur higher in the succession but both their small size and uncertain archaeopyle type suggest another classification for those specimens. Rigaudella aemula (Fig. 6I) commonly occurs up to the lower A. glosense ammonite Zone and A. ilovaiskii Sub- zone. Leptodinium subtile (Fig. 6M–N) and Leptodinium mirabile appear contemporaneously in this horizon, but only L. subtile occurs regularly in higher strata. Ambono- sphaera staffinensis (Fig. 6J–K), S. inritibile (Fig. 6O–P) and Systematophora valensii (Fig. 6L) appear from this hori- zon and continue above the S. crystallinum Zone. Compositosphaeridium polonicum (Fig. 6Q–R) occurs consistently but not commonly, with a highest occur- rence in the lower A. glosense ammonite Zone and A. ilovaiskii Subzone. The lowermost occurrence of D. minutum (Fig. 7A–E) appears in A. glosense ammonite Zone and A. ilovaiskii Subzone. Specimens of D. minutum may represent mor- phological variants of A. staffinensis (Fig. 6J–K) since spec- imens occur with apparent transitional morphology. However, D. minutum has a prominent tabulation, an antapical keel with a vertical antapical plate on the ven- tral side and a prominent flagellar scar in the mid-sulcal area. D. minutum was previously informally recorded as A. ‘utera’ by Piasecki (1980). Kalyptea stegasta (Fig. 7F–G) is common and has a clear uppermost occurrence in the upper A. glosense ammonite Zone. It is recorded higher neither in the S. crystallinum Zone nor above, but it is recorded to the top of the lower Volgian in North-West Europe (Riding & Thomas 1992). Dingodinium jurassicum (Fig. 7H) is present in the uppermost sample from the A. glosense ammonite Zone of Kosmocerasdal Member and the three lowermost samples of locality 39 in the upper A. glosense/A. serratum ammonite Zone. The short range of this species appar- ently forms a stratigraphically narrow and locally useful occurrence. A few instances of Dingodinium tuberosum (Fig. 7I) are also recorded in the lowermost level with D. jurassicum. This deviates from North-West Europe, where the first occurrences of D. jurassicum and D. tuberosum are recorded at stratigraphically different lev- els: lower and higher, respectively (e.g. Riding & Thomas 1992; Poulsen 1996). The sculpture of the endophragm and the overall shape and morphology of D. jurassicum are quite different from D. tuberosum (Fig. 7H–I). Hystrichosphaerina orbifera (Fig. 7L) appears in the upper A. glosense/A. serratum ammonite zones. Chorate cysts are rare in most samples and mostly too crushed or degraded for reliable identification. In comparison, the characteristic process complexes of H. orbifera make it an identifiable species. Paragonyaulacysta borealis (Fig. 7O–P) also appears in this sample. In East Greenland, P. borealis is obviously tabulated but with vague para- sutures. Hence, specimens are mostly identified on the basis of overall size, shape, surface sculpture of the autophragm and the apicular structure in comparison with more distinct tabulated specimens in North-East and North Greenland. Gonyaulacysta adecta (Fig. 7Q–R) occurs highest in the A. rosenkrantzi ammonite Zone. G. adecta is basically a G. jurassica but lacking a hypocoel. All morphological struc- ture on G. jurassica varies radically possibly in response to environmental or climatic conditions. Endoscrinium irregulare (Fig. 7S–V) appears in the same sample level. E. irregulare is not considered stratigraphically signifi- cant, but it has a significant morphology and a clear first occurrence in the A. rosenkrantzi ammonite Zone. Scriniodinium crystallinum (Fig. 6A–B) has its highest occurrence in the top of the A. rosenkrantzi ammonite Figure 7 continued sample numbers, slide number and England Finder coordinates. The illustrated specimens are marked with a red circle on the original slide. A: Din- godinium minutum, locality 6, sample GGU245827, slide 8, E.F. G32/2. Magnified x600. B: Dingodinium minutum, locality 6, sample GGU245828, slide 8, E.F. S53/3. Magnified x600. Scale in A. C, D: Dingodinium minutum, high and low focus, locality 6, sample GGU245830, slide 9, E.F. J47. Magnified x600. Scale in A. E: Dingodinium minutum, locality 6, sample GGU245830, slide 9, E.F. H29. Magnified x600. Scale in A. F: Kalyptea stegasta, locality 2, sample GGU234159, slide 8, E.F. T27/4. Magnified x400. G: Kalyptea stegasta, locality 2, sample GGU234239, slide 4, E.F. G34. Magnified x400. Scale in F. H: Dingodinium jurassicum, locality 39, sample GGU234231, slide 9, U37/2. Magnified x400. Scale in F. I: Dingodinium tuberosum, locality 39, sample GGU234231, slide 6, G23/3. Magnified x400. Scale in F. J, K: Stephanelytron redcliffense, high and low focus, locality 39, sample GGU234232, slide 3, E.F. M27/1. Magnified x400. Scale in F. L: Systematophora areolata, locality 39, sample GGU234230, slide 3, E.F. V37/1. Magnified x400. Scale in F. M: Hystrichosphaerina orbifera, locality 39, sample GGU234221, slide 3, E.F. O49/2. Magnified x400. Scale in F. N: Hystrichosphaerina orbifera, locality 39, sample GGU234220, slide 3, E.F. N45/2. Magnified x400. Scale in F. O: Paragonyaulacysta borealis, locality 39, sample GGU234223, slide 6, E.F. O39/3. Magnified x400. Scale in F. P: Paragonyaulacysta borealis, locality 6, sample GGU245827, slide 8, E.F. R32/3-S32/1. Magnified x400. Scale in F. Q: Gonyaulacysta adecta, locality 39, sample GGU234228, slide 10, E.F. J48/2. Magnified x400. Scale in F. R: Gonyaulacysta adecta, locality 39, sample GGU234232, slide 3, E.F. P23. Magnified x400. Scale in F. S: Endoscrinium irregulare, locality 39, sample GGU234224, slide 7, E.F. T28/3–4. Magnified x400. Scale in F. T: Endoscrinium irregulare, locality 39, sample GGU234220, slide 7, E.F. S48. Magnified x400. Scale in F. U: Endoscrinium irregulare, locality 39, sample GGU234220, slide 6, E.F. N45.4. Magnified x400. Scale in F. V: Endoscrinium irregulare, locality 6, sample GGU245827, slide 8, E.F. W35. Magnified x600. https://doi.org/10.34194/geusb.v57.8373 http://www.geusbulletin.org/ Piasecki 2024: GEUS Bulletin 57. 8373. https://doi.org/10.34194/geusb.v57.8373 12 of 15 GEUSBULLETIN.ORG Zone at locality 39. Rare specimens have been recorded much higher in the succession at other localities, but they are considered to have been reworked or are pos- sibly misinterpretations. Dingodinium minutum (Fig. 7A–E) occurs highest into the P. baylei ammonite Zone, lowermost Kimmeridgian. This is higher than the S. crystallinum Zone and the low- ermost E. luridum Zone. Ammonite Zones P. baylei D. minutum A. rosenkrantzii W an ae a fim br ia ta A. regulare A. serratum A. glosense C. tenuiserratum C. densiplicatum C. cordatum Q. mariae (Q. lamberti?) P. athleta Range of index species Events LADs FADs O xf or di an K im m er id ia n D in of la ge lla te cy st z on es S . c ry st al lin um T. s ca rb ur gh en se W . F im br ia ta C al lo vi an Tr ic ho di ni um s ca rb ur gh en se S cr in io di ni um c ry st al lin um E nd os cr in iu m lu rid um G. adecta S. redcliffense K. stegasta C. polonicum / R. aemula T. scarburghense W. fimbriata LAD: Last Apperance Datum S. crystallinum E. irregulare P. borealis / H. orbifera D. jurassicum S. crystallinum W. fimbriata T. scarburghense FAD: First Apperance Datum Legend D. minutum * * E. luridum L. subtile A. staffinensis S. valensii S. inritibile Lo w er M id dl e U pp er Fig. 8 Schematic correlation of the Oxfordian ammonite zones, dinoflagellate cyst zones and events on Milne Land, East Greenland. https://doi.org/10.34194/geusb.v57.8373 http://www.geusbulletin.org/ Piasecki 2024: GEUS Bulletin 57. 8373. https://doi.org/10.34194/geusb.v57.8373 13 of 15 GEUSBULLETIN.ORG 4 Discussion The S. crystallinum Zone appears to be a useful iden- tifier of middle to upper Oxfordian strata in East Greenland based on palynological analyses (Fig. 8). Seventeen dinoflagellate cyst events characterise the lower and upper boundaries and subdivide the zone into 10 units. The dinoflagellate cyst zone correlates with five succeeding ammonite zones, from lower- most to uppermost: the C. tenuiserratum, A. glosense, A. serratum, A. regulare and A. rosenkrantzi zones. The stratigraphical positions of both base and top of the S. crystallinum Zone in the study area deviate slightly from the corresponding zone in North-West Europe, but this may reflect the limited amount or spacing of samples studied in East Greenland. Barski (2018) shows that common S. crystallinum reaches into the lower P. Baylei ammonite Zone on the Isle of Skye, Scotland. However, other dinoflagellate cyst studies in North-West Europe show different stratigraphical ranges to East Green- land, such as Perisseiasphaeridium pannosum and Seno- niasphaera jurassica. Most of the events in North-West Europe applied for stratigraphical subdivision of zones into subzones do not appear at the same stratigraphi- cal levels in East Greenland. The lowermost appearance of T. scarburghense is between two faunal horizons of M 2 in Kosmocerasdal and is referred to the P. athleta ammonite Zone (Fig. 4). The lower boundary of the W. fimbriata Zone (Smelror 1988) was defined by the first occurrence of W. fimbriata below faunal horizon M 3, Q. mariae ammonite Zone. The assumed Q. lamberti ammonite Zone beneath fau- nal horizon M 3 is not recorded in the Kosmocerasdal succession (locality 2), but the lower boundary of the W. fimbriata Zone is still hypothetically referred to this ammonite zone marked by (?) in Fig. 8. The lower boundary of the T. scarburghense Zone (Smelror 1988) was defined by the highest occurrence of W. fimbriata, now referred to the lower Cardioceras cordatum ammonite Zone (Fig. 8). The lower boundary of the S. crystallinum Zone in East Greenland coincides with the highest occurrence of T. scarburghense Zone (Smelror 1988) defined by the high- est occurrence of T. scarburghense in the C. tenuiserratum ammonite Zone (Fig. 8). The upper zonal boundary is in the uppermost A. rosenkrantzi ammonite Zone and not the P. baylei ammonite Zone as in North-West Europe. Some recorded species may have a slightly prob- lematic taxonomic affinity due to vaguely expressed morphological characters or bad preservation. Parago- nyaulacysta borealis has very discrete tabulation on Milne Land, but it is recorded consistently from Jameson Land towards the north along East and North-East Greenland to North Greenland (Håkansson et al. 1981). A. staffinensis and D. minutum appear to have transitional morphologies, and the distinction between the two may be uncertain in some cases. Some C. cerastes-shaped specimens have been excluded here due to their small size and incomplete archaeopyles, and many System- atophora-like specimens cannot be identified to species level due to fragmentation, folding or bad preservation. Epiplosphaera saturnalis is not typically recorded here, but the reduced surface sculptural elements on E. cf. saturnalis are similar to the elements of the holotype (Brideaux & Fisher 1976; plate 6, figs 1–7 and plate 7, fig.  10). Comparable specimens have been recorded from Milne Land to North Greenland as Lanterna satur- nalis (Håkansson et al. 1981). 5 Conclusions In this study, the history of Oxfordian dinoflagellate cyst stratigraphy in East Greenland is summarised and updated. The dinoflagellate cysts stratigraphy of the marine deposited, Middle to Upper Jurassic suc- cession is documented and correlated with ammonite stratigraphy. It is found that the S. crystallinum Zone from North- West Europe is applicable in East Greenland in its original definition. However, the later associated stratigraphical markers for both the lower and upper boundary are not directly applicable in East Greenland. The subdivision of five subzones in North-West Europe is mostly based on species that are rare or absent in the East Greenland, including the first and last subzones (DJS23 and -27), which are not included in the S. crystallinum Zone in East Greenland. Fifteen events are suggested to subdivide the S. crys- tallinum zone into 10 units by characteristic and com- mon species in East Greenland. The zonal boundaries and the stratigraphic events are directly integrated with the ammonite stratigraphy. The S. crystallinum Zone is applicable in the Jurassic sedimentary basins of East and North-East Greenland and may be applicable in parts of the North Atlantic region. With this contribution to the Jurassic biostratigraphy in East Greenland and together with the Upper Jurassic biostratigraphy of two previously drilled cores Rødryg- gen-1 and Brorson Halvø-1, the whole Jurassic succession in East Greenland has now been palynologically analysed based on spores and pollen or dinoflagellate cysts. Acknowledgements Kim Villadsen, Palynological Laboratory, prepared the analysed sam- ples. The present manuscript was compiled as emeritus at the Globe Institute, University of Copenhagen. Staff in the Department of Geo- physics and Sedimentary Basins, Geological Survey of Denmark and Greenland (GEUS), helped draw the figures. Peter Alsen is thanked for helpful criticism of the manuscript and the results. The reviewers J.B. Riding and Morten Smelror are thanked for helpful corrections of the text and suggested improvements of the content. https://doi.org/10.34194/geusb.v57.8373 http://www.geusbulletin.org/ Piasecki 2024: GEUS Bulletin 57. 8373. https://doi.org/10.34194/geusb.v57.8373 14 of 15 GEUSBULLETIN.ORG Additional information Funding statement The original fieldwork and office studies were financed by Danish Natu- ral Science Research Foundation grants in 1977–1980. Conflict of interests The author declares no competing interests. Author contributions SP: Conceptualisation; Investigation; Visualisation; Writing – original draft; Writing – review and editing. References Alsen, P. & Piasecki, S. 2018: Biostratigraphy of the Hareelv Formation (Upper Jurassic) in the Blokelv-1 core, Jameson Land, central East Greenland. Geological Survey of Denmark and Greenland Bulletin 42, 15–37. https://doi.org/10.34194/geusb.v42.4308 Alsen, P., Piasecki, S., Nøhr-Hansen, H., Pauly, S., Sheldon, E. & Hovikoski, J. 2023: Stratigraphy of the Upper Jurassic to lowermost Cretaceous in the Rødryggen-1 and Brorson Halvø-1 boreholes, Wollaston Forland, NE Greenland. GEUS Bulletin 55, 8342. https://doi.org/10.34194/geusb.v55.8342 Bailey, D. 2023: Biostratigraphic consultancy company. BioStrat Ltd. http://www.biostrat.org.uk/ (accessed 10 June 2023) Barski, M. 2018: Dinoflagellate cyst assemblages across the Oxfordian/ Kimmeridgian boundary (Upper Jurassica) at Flodigarry, Staffin Bay, Isle of Skye, Scotland – a proposed GSSP for the base of the Kimmeridgian. Volumina Jurassica XVI, 51–62. https://doi.org/10.5604/01.3001.0012.4594 Birkelund, T. & Callomon, J.H. 1985: The Kimmeridgian ammonite faunas of Milne Land, central East Greenland. Grønlands geologiske Undersø- gelse Bulletin 53, 56 pp. https://doi.org/10.34194/bullggu.v153.6695 Birkelund, T., Callomon, J.H. & Fürsich, F.T. 1984: The stratigraphy of the Upper Jurassic and Lower Cretaceous sediments of Milne Land, cen- tral East Greenland. Grønlands geologiske Undersøgelse Bulletin 147, 56 pp. https://doi.org/10.34194/bullggu.v147.6689 Bjerager, M., Alsen, P., Bojesen-Kofoed, J.A., Nielsen, T., Piasecki, S. & Pilgaard, A. 2018: Late Jurassic evolution of the Jameson Land Basin, East Greenland – implications of the Blokelv-1 borehole. Geological Survey of Denmark and Greenland Bulletin 42, 149–168. https://doi. org/10.34194/geusb.v42.4325 Brideaux, W.W. & Fisher, M.J. 1976: Upper Jurassic – Lower Cretaceous dinoflagellate assemblages from Arctic Canada. Geological Survey of Canada Bulletin 259, 53 pp. https://doi.org/10.4095/119813 Bujak, J., Bringué, M., Goryacheva, A.A., Lebedeva, N.K., Pestchevits- kaya, E.B., Riding, J.B. & Smelror, M. 2022: Jurassic palynoevents in the circum-Arctic region. Atlantic Geoscience 58, 55–98. https://doi. org/10.4138/atlgeo.2022.003 Callomon, J.H. 1984: Biostratigraphy, chronostratigraphy and all that – again! In: Michelsen, O. & Zeiss, A. (eds): International Symposium on Jurassic Stratigraphy (Erlangen 1984) 3, 611–624. Copenhagen: Geo- logical Survey of Denmark. Callomon, J.H. 1993: The ammonite succession in the Middle Jurassic of East Greenland. Bulletin Geological Society of Denmark 40, 83–113. https://doi.org/10.37570/bgsd-1994-40-03 Callomon, J.H., Alsen, P. & Surlyk, F. 2015: The ammonites of the Middle Jurassic Cranocephalites beds of East Greenland. Geological Survey of Denmark and Greenland Bulletin 34, 148 pp. https://doi.org/10.34194/ geusb.v34.4488 Callomon, J.H. & Birkelund, T. 1980: The Jurassic transgression and the mid-late Jurassic succession in Milne Land, central East Green- land. Geological Magazine 117, 3, 211–226. https://doi.org/10.1017/ s0016756800030442 Fensome, R.A. 1979: Dinoflagellate cysts and acritarchs from the Mid- dle and Upper Jurassic of Jameson Land, east Greenland. Grønlands Geologiske Undersøgelse Bulletin 132, 1–98. https://doi.org/10.34194/ bullggu.v132.6674 Fensome, R.A., Williams, G.L. & MacRae, R.A. 2019: The Lentin and Williams index of fossil dinoflagellates 2019 edition. American Association of Stratigraphic Palynologists Contributions Series 50, 1173. https://doi.org/10.4095/103330 Fürsich, F.T. & Heinberg, C. 1983: Sedimentology, biostratinomy and palaeoecology of an Upper Jurassic offshore sand bar complex. Bulletin of the Geological Society of Denmark 32, 67–95. https://doi. org/10.37570/bgsd-1983-32-04 Håkansson, E., Birkelund, T., Piasecki, S. & Zakharov, V. 1981: Juras- sic-Cretaceous boundary strata of the extreme Arctic (Peary Land, North Greenland). Bulletin of the Geological Society of Denmark 30, 11–42. https://doi.org/10.37570/bgsd-1981-30-02 Hansen, J.M. & Gudmundsson, L. 1979: A method for separating acid-in- soluble microfossils from organic debris. Micropaleontology 25(2), 113–117. https://doi.org/10.2307/1485261 Kelly, S.R.A., Gregory, F.J., Braham, W., Strogen, D.P. and Whitham, A.G. 2015: Towards an integrated Jurassic biostratigraphy for eastern Greenland. Volumina Jurassica XIII(1), 43–64. https://doi. org/10.5604/17313708.1148657 Larsen, M., Piasecki, S. & Surlyk, F. 2003: Stratigraphy and sedimentol- ogy of a basement onlapping shallow marine sandstone succession, the Charcot Bugt Formation, Middle–Upper Jurassic, East Greenland. Geological Survey of Denmark and Greenland Bulletin 1, 893–930. https://doi.org/10.34194/geusb.v1.4693 Larsen, M. & Surlyk, F. 2003: Shelf-edge delta and slope deposition in the Upper Callovian – Middle Oxfordian Olympen Formation, East Greenland. Geological Survey of Denmark and Greenland Bulletin 1, 893–930. https://doi.org/10.34194/geusb.v1.4695 Monteil, E. 1996: Nidarocysta jubilaea gen. et sp. nov., a new gonyau- lacacean dinoflagellate cyst marker of the Oxfordian-Kimmeridgian boundary in the European boreal province. Bulletin des Centres de Recherches Exploration – Production Elf-Aquitaine 20(2), 389–413. Nøhr-Hansen, H. 1986: Dinocyst stratigraphy of the Lower Kimme- ridge Clay, Westbury, England. Bulletin of the Geological Society of Denmark 35, 31–51. https://doi.org/10.37570/bgsd-1986-35-05 Piasecki, S. 1980: Middle to Late Jurassic dinoflagellate cyst stratigraphy from Milne Land and Jameson Land (East Greenland) correlated with ammonite stratigraphy. Unpublished PhD thesis, University of Copen- hagen, Denmark. Piasecki, S., Larsen, M., Therkelsen, J. & Vosgerau, H. 2004: Jurassic dinoflagellate cyst stratigraphy of Hold with Hope, North-East Green- land. Geological Survey of Denmark and Greenland Bulletin 5, 73–88. https://doi.org/10.34194/geusb.v5.4808 Piasecki, S. & Stemmerik, L. 2004: Jurassic dinoflagellate cysts from Hoch- stetter Forland, North-East Greenland. Geological Survey of Denmark and Greenland Bulletin 5, 88–97. https://doi.org/10.34194/geusb.v5.4809 Pocock, S.A.J. & Sarjeant, W.A.S. 1972: Partitomorphitae, a new subgroup of Triassic and Jurassic acritarchs. Bulletin of the Geological Society of Denmark 21, 346–357. Poulsen, N.E. 1985: Dinocyst stratigrafien i den nedre del af Hareelv For- mationen (Øvre Jura), Jameson Land, Østgrønland. Årsskrift for Dansk Geologisk Forening 1984, 133–137. Poulsen, N.E. 1996: Dinoflagellate cysts from marine Jurassic deposits of Denmark and Poland. American Association of Stratigraphic Palynol- ogist, Contributions Series 31, 227 pp. Poulsen, N.E. & Riding, J.B. 2003: The Jurassic dinoflagellate cyst zonation of subboreal Northwest Europe. Geological Survey of Denmark and Greenland Bulletin 1, 115–144. https://doi.org/10.34194/geusb.v1.4650 Riding, J.B., Mariani, E. & Fensome, R.A. 2022: A review of the Jurassic dinoflagellate cyst genus Gonyaulacysta Deflandre 1964 emend. nov. Review of Palaeobotany and Palynology 299, 1–37. https://doi. org/10.1016/j.revpalbo.2022.104605 Riding, J.B. & Thomas, J.E. 1988: Dinoflagellate cyst stratigraphy of the Kim- meridge Clay (Upper Jurassic) from the Dorset coast, southern England. Palynology 12, 65–88. https://doi.org/10.1080/01916122.1988.9989337 Riding, J.B. & Thomas, J.E. 1992: Dinoflagellate cysts of the Jurassic System. In: Powell, A.J. (ed): A stratigraphic index of dinoflagellate cysts, 7–97. Lon- don: Chapman and Hall. https://doi.org/10.1080/01916122.1988.9989337 Riding, J.B. & Thomas, J.E. 1997: Marine palynomorphs from Staffin Bay and Staffin Shale formations (Middle–Upper Jurassic) of the Trotter- nish Peninsula, NW Skye. Scottish Journal of Geology 33(1), 59–74. https://doi.org/10.1144/sjg33010059 https://doi.org/10.34194/geusb.v57.8373 http://www.geusbulletin.org/ https://doi.org/10.34194/geusb.v42.4308 https://doi.org/10.34194/geusb.v55.8342 http://www.biostrat.org.uk/ https://doi.org/10.5604/01.3001.0012.4594 https://doi.org/10.34194/bullggu.v153.6695 https://doi.org/10.34194/bullggu.v147.6689 https://doi.org/10.34194/geusb.v42.4325 https://doi.org/10.34194/geusb.v42.4325 https://doi.org/10.4095/119813 https://doi.org/10.4138/atlgeo.2022.003 https://doi.org/10.4138/atlgeo.2022.003 https://doi.org/10.37570/bgsd-1994-40-03 https://doi.org/10.34194/geusb.v34.4488 https://doi.org/10.34194/geusb.v34.4488 https://doi.org/10.1017/s0016756800030442 https://doi.org/10.1017/s0016756800030442 https://doi.org/10.34194/bullggu.v132.6674 https://doi.org/10.34194/bullggu.v132.6674 https://doi.org/10.4095/103330 https://doi.org/10.37570/bgsd-1983-32-04 https://doi.org/10.37570/bgsd-1983-32-04 https://doi.org/10.37570/bgsd-1981-30-02 https://doi.org/10.2307/1485261 https://doi.org/10.5604/17313708.1148657 https://doi.org/10.5604/17313708.1148657 https://doi.org/10.34194/geusb.v1.4693 https://doi.org/10.34194/geusb.v1.4695 https://doi.org/10.37570/bgsd-1986-35-05 https://doi.org/10.34194/geusb.v5.4808 https://doi.org/10.34194/geusb.v5.4809 https://doi.org/10.34194/geusb.v1.4650 https://doi.org/10.1016/j.revpalbo.2022.104605 https://doi.org/10.1016/j.revpalbo.2022.104605 https://doi.org/10.1080/01916122.1988.9989337 https://doi.org/10.1080/01916122.1988.9989337 https://doi.org/10.1144/sjg33010059 Piasecki 2024: GEUS Bulletin 57. 8373. https://doi.org/10.34194/geusb.v57.8373 15 of 15 GEUSBULLETIN.ORG Sarjeant, W.A.S. 1972: Dinoflagellate cysts and acritarchs from the upper Vardekløft Formation (Jurassic) of Jameson Land, East Greenland. Meddelelser om Grønland 195(4), 64 pp. Smelror, M. 1988: Late Bathonian to early Oxfordian dinoflagellate cysts stratigraphy of Jameson Land and Milne Land, East Greenland. Grøn- lands Geologiske Undersøgelse Rapport 137, 135–159. https://doi. org/10.34194/rapggu.v137.8019 Smelror, M. 2021: Palynostratigraphy, Palynofacies, T-R cycles and Paleoenvironments in the Middle Jurassic–Early Cretaceous Ramså Basin, Andøya, Northern Norway. Geosciences 11, 354. https://doi. org/10.3390/geosciences11090354 Surlyk, F. et al. 2021: Jurassic stratigraphy of East Greenland. Geologi- cal Survey of Denmark and Greenland Bulletin 46, 6521. https://doi. org/10.34194/geusb.v46.6521 Surlyk, F., Alsen, P., Hovikoski, J. & Piasecki, S. 2023: Uplift, deflation and marine onlap of a Jurassic rift dome, illustrated by a backstep- ping Middle–Upper Jurassic shelf-to-slope succession, Geograph- ical Society Ø, East Greenland. Terra Nova 35, 506–513. https://doi. org/10.1111/ter.12673 Surlyk, F., Callomon, J.H., Bromly, R.G. & Birkelund, T. 1973: Stratigra- phy of the Jurassic–Lower Cretaceous sediments of Jameson Land and Scoresby Land, East Greenland. Grønlands Geologiske Undersø- gelse, Bulletin 105, 94 pp. https://doi.org/10.34194/bullggu.v105.6646 Sykes, R.M. & Surlyk, F. 1976: A revised ammonite zonation of the Boreal Oxfordian and its application in northeast Greenland. Lethaia 9, 421–436. https://doi.org/10.1111/j.1502-3931.1976.tb00984.x Woollam, R. & Riding, J.B. 1983: Dinoflagellate cyst zonation of the English Jurassic. Institute of Geological Sciences Report 83(2), 1–42. https://doi.org/10.34194/geusb.v57.8373 http://www.geusbulletin.org/ https://doi.org/10.34194/rapggu.v137.8019 https://doi.org/10.34194/rapggu.v137.8019 https://doi.org/10.3390/geosciences11090354 https://doi.org/10.3390/geosciences11090354 https://doi.org/10.34194/geusb.v46.6521 https://doi.org/10.34194/geusb.v46.6521 https://doi.org/10.1111/ter.12673 https://doi.org/10.1111/ter.12673 https://doi.org/10.34194/bullggu.v105.6646 https://doi.org/10.1111/j.1502-3931.1976.tb00984.x The Scriniodinium crystallinum dinoflagellate cyst zone in the Middle-Upper Oxfordian, Upper Jurassi 1 Introduction 2 Material and methods 2.1 History of dinoflagellate cyst stratigraphy in East Greenland 2.2 Biozonation 3 Results 4 Discussion 5 Conclusions Acknowledgements Additional information Funding statement Conflict of interests Author contributions References Figures Fig. 1 Map of the study area. A: Geological map of East Greenland (modified from Surlyk et al. 2021) with locations of the Rødryggen-1 and Brorson Halvø-1 drilling sites. Inset: maps of localities analysed in this study. B: Jameson Land with Blokelv-1 core and C: Ilimananngip Nunaa (Milne Land) with localities M 2, 3, 4, 5, 6 and 39 (locality numbers sensu Birkelund et al. 1984). Fig. 2 Lithostratigraphical scheme of Jurassic to Lower Cretaceous sediments on Milne Land based on Callomon & Birkelund (1980), Birkelund & Callomon (1985), Birkelund et al. (1984) and Surlyk et al. (2021). Fig. 3 Ammonite faunal horizons on Milne Land correlated with ammonite zones (Callomon & Birkelund 1980; Birkelund & Callomon 1985). Shading indicates the faunal province affiliations. Fig. 4 Measured and sampled sedimentary successions from Milne Land with ammonite faunal horizons (e.g. M 14) and palynological samples (e.g. GGU245951) modified from Piasecki (1980). The locality numbers are from Piasecki (1980, fig.3) and Birkelund & Callomon (1985, fig. 2). The sedimentary succession from localities 2–5 shows the complete Kosmocerasdal Member, Kap Leslie Formation. Sedimentary logs from locality 6, Cardioceraskløft, and locality 39, east of Visdal, are correlated by the upper boundary of Aldinger Elv Member and the basis of Bays Elv Member. Fig. 5 Dinoflagellate cyst range-chart based on data from a composite succession of Kosmocerasdal Member to Bays Elv Member, Kap Leslie Formation. The range-chart is combined from successions at localities 2–5 and 39. To fit to the page, the composite succession of Kosmocerasdal Member is reduced 4 times in thickness and arranged from 0 to –25 m. The succession from locality 39 is shown to scale and spans 34 m from the basis of Kosmocerasdal Member to the top of Bays Elv Member. Abbreviations: Mid.: middle. *1: Aldinger Elv Mb. *2: Kimmeridgian. Dinoflagellate cyst names in Figs 5–7. Fig. 6 Stratigraphically significant dinoflagellate cysts from the middle to upper Oxfordian S. crystallinum Zone in Milne Land, from locality 39, east of Visdal, and localities 2 (Kosmoceras Dal), 3 (Nordøstelv) and 4 (‘Hystrix’ Dal), eastern Milne Land (locations in Fig. 1). The illustrated specimens are referred to locality numbers, GGU sample number, slide number and England Finder coordinates. The illustrated specimens are marked with a red circle on the original slides. Magnification is x400 as indicated by a 25 μm scalebar in panel A that applies to all figures. A: Scriniodinium crystallinum, locality 39, sample GGU234229, slide 7, E.F. U35/2. B: Scriniodinium crystallinum, locality 39, sample GGU234229, slide 7, E.F. P25/2. C: Trichodinium scarburghense, locality 2, sample GGU234235, slide 4, E.F. K29/4. D: Trichodinium scarburghense, locality 2, sample GGU234235, slide 4, T34/3. E, F: Atopodinium haromense, high and low focus, locality 3, Fig. 7 Stratigraphically significant dinoflagellate cysts from the middle to upper Oxfordian in Milne Land from locality 39, Kosmoceras Dal, east of Visdal, and localities 2 and 6, Cardioceraskløft, in eastern Milne Land (locations in Fig. 1). The illustrated specimens are referred to locality numbers, GGU sample numbers, slide number and England Finder coordinates. The illustrated specimens are marked with a red circle on the original slide. A: Dingodinium Fig. 8 Schematic correlation of the Oxfordian ammonite zones, dinoflagellate cyst zones and events on Milne Land, East Greenland.