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Chapter 13. Biozonation of the Jurassic – lowermost Cretaceous of the North Sea region

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Abstract

An updated, integrated biozonation scheme for the Jurassic (Hettangian) – lowermost Cretaceous (Upper Berriasian) of the North Sea Basin incorporates 49 palynology biozones plus subzones (based on dinocysts, spores and pollen) and 27 microfaunal zones plus subzones (based on foraminifera, radiolaria and ostracods), to provide the essential chronostratigraphic calibration of the defined sequences. The biozonation scheme is tied to standard ammonite zonal chronostratigraphy wherever possible. Parts of the biozonation scheme are also applicable to onshore UK (boreholes and outcrops), onshore Denmark (boreholes) and to offshore Netherlands.

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DINOSTRAT version 2.1-GTS2020 is now available (10.5281/zenodo.10506652, Bijl et al., 2024b). This version updates DINOSTRAT to the Geologic Time Scale 2020, and new publications are added into the database. The resulting database now contains over 9450 entries from 209 sites. This update has not led to major and profound changes in the conclusions made previously. DINOSTRAT allows full presentation of the first and last stratigraphic occurrences of dinoflagellate cyst subfamilies and families, as well as the evolutionary turnover throughout geologic history, as a reliable representation of dinoflagellate evolution. Although the picture of dinoflagellate evolution from DINOSTRAT is broadly consistent with that in previous publications, with DINOSTRAT the underlying data are openly available, reproducible and up to date. This release of DINOSTRAT allows calibration of stratigraphic records to the Geologic Time Scale 2020 using dinoflagellate cysts as a biostratigraphic tool.
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Article
Dinoflagellates and coccolithophores are two of the most important groups of phytoplankton in the modern oceans. These groups originated in the Triassic and radiated through the early Mesozoic, rising to ecological prominence. Within this long-term radiation, important short-term intervals of evolutionary and ecological change can be recognised. The Bajocian (Middle Jurassic, ~170–168 Ma) was characterised by an important ecological transition within the coccolithophores, and the radiation of one of the principal families of cyst-forming dinoflagellates, the Gonyaulacaceae. During the Early Bajocian, the coccolith genus Watznaueria diversified and expanded ecologically to dominate coccolith floras, a situation which continued for the remainder of the Mesozoic. This pattern was paralleled within dinoflagellate cyst floras by the ecological dominance of the genus Dissiliodinium in the mid-palaeolatitudes. These phenomena appear to be linked to a positive carbon isotope shift, and an interval of enhanced productivity driven by a shift to a more humid climate, enhanced continental weathering and nutrient flux, or by changes in ocean circulation and upwelling. The latest Early Bajocian to earliest Bathonian was then characterised by the rapid increase in diversity of dinoflagellate cysts within the family Gonyaulacaceae. Through this interval, the Gonyaulacaceae transitioned from being a relatively minor component of dinoflagellate cyst floras, to becoming one of the prominent groups of cyst-forming dinoflagellates, which has persisted to the Holocene. In Europe, the pattern of this radiation was strongly influenced by sea level, with the increase in gonyaulacacean diversity reflecting a major second-order transgression. On a finer scale, the main pulses of first appearances correlate with third-order transgressive episodes. A rise in sea level, coupled with changes in the tectonic configuration of ocean gateways, appears to have controlled the pattern of plankton diversification in Europe. These palaeoceanographic changes may have enhanced water-mass transfer between Europe, the northwest Tethys Ocean and the Hispanic Corridor, which promoted the floral interchange of dinoflagellates. Whilst sea level rise and associated large-scale palaeoenvironmental shifts appear to have controlled the pattern of dinoflagellate cyst appearances in several regions outside Europe, there is no direct correlation between dinoflagellate cyst diversity and sea level rise on a global scale. Although the Bajocian was transgressive in several regions, widespread flooded continental area was also present throughout the preceding Aalenian, an interval of low gonyaulacacean diversity. Moreover, although the Middle Jurassic was an interval of major climatic cooling, there was a ~5 myr gap between the onset of cooling and the radiation of gonyaulacaceans during the Bajocian. The Bajocian was, however, marked by a major evolutionary radiation in the pelagic realm, including ammonites, giant suspension feeding fishes and planktonic foraminifera. These phenomena may indicate an underlying ecological driver to the radiation of dinoflagellates during the Bajocian evolutionary explosion which could represent an extension of the Mesozoic Marine Revolution.
Article
A comprehensive investigation of the Early Jurassic stratigraphical palynology of the Lusitanian Basin in western Portugal was undertaken, with most emphasis placed on dinoflagellate cysts. A total of 214 samples from an upper Sinemurian to upper Toarcian composite section based on six successions were examined. The Sinemurian material examined was barren of dinoflagellate cysts; however, the Pliensbachian and Toarcian successions are characterised by relatively low diversities where Luehndea spinosa, Mancodinium semitabulatum, Mendicodinium microscabratum, Nannoceratopsis gracilis, Nannoceratopsis senex, and Scriniocassis priscus are relatively common and biostratigraphically significant. Luehndea spinosa dominates the lowermost Toarcian (Dactylioceras polymorphum ammonite Biozone), and is an index species. At the base of the Hildaites levisoni ammonite Biozone, the effects of the Toarcian-Oceanic Anoxic Event (T-OAE) caused Luehndea spinosa to become extinct. At the same time, dinoflagellate cyst abundance and diversity markedly decreased. After the T-OAE, during the middle and late Toarcian, phytoplankton recovery was prolonged and slow in the Lusitanian Basin. The Luehndea spinosa and Mendicodinium microscabratum dinoflagellate cyst biozones are defined, both of which are subdivided into two dinoflagellate cyst subbiozones.
Article
Core samples from five wells of the Statfjord area were analysed for foraminifera. The material covers the middle and upper parts of the deltaic marine Dunlin Formation and the basal deposits of the deltaic Brent Formation through an interval ranging in age from Pliensbachian to Toarcian or early Bajocian. The quantitative distribution of genera and other major faunal parameters define the following five assemblages which reflect successive steps in the evolution of the depositional basin (in ascending order): the Dentalina‐Nodosaria, Ammodiscus‐Dentalina and Marginulina assemblages developed in a delta‐influenced shelf embayment; the Trochammina‐Verneuilinoides assemblage formed under prodelta conditions; the Ammodiscus assemblage deposited in a delta‐front environment. The specific composition of the assemblages is illustrated by quantitative examples.
Article
Outcrops of the Early Bajocian, Gristhorpe Member (Ravenscar Group) in North Yorkshire have been subjected to a multi-disciplinary analysis which establishes a key reference section at Yons Nab. Eight micro-biofaces types (MBs) are defined based on counts of transitional marine microfaunas, megaspores and plant-derived debris. Associated palynofloral associations (PAs) are used to qualify the micro-biofacies defined to provide an integrated model for interpreting salinity-freshwater trends associated with deltaic progradation and retreat. Megaspore and small-spore trends within the delta-plain are shown to have been closely linked to peat-mires forming in topographic lows, with variations across the delta-plain attributable to the presence of the semi-permanent and seasonal water tables. A reconstruction of the floodplain-peat-mire depositional setting is proposed where the composition of host vegetation (e.g. ferns, lycopsids) varied in relation to groundwater levels. Biostratigraphic correlation within the Gristhorpe Member is attempted using the base of 'established' delta-plain deposition (megaspore dominant MBsspore-dominant PAs) and the top and base agglutinated foraminifera-dominant MBs (brackish). Using these criteria the Gristhorpe Member is modelled in terms of a southward progradation of delta-plain facies into a bay-fill sequence, which persisted at Yons Nab. With the delta-plain established, the MBPA trends and sedimentology suggest a northward shift towards the higher delta-plain, with seasonal standing water only. The MBPA model was tested on core samples from the coeval lower Brent Group from northern North Sea well 3410-B-12 (Gullfaks Field); MBPA trends are shown to compare closely with those of the Gristhorpe Member at Yons Nab, with the same megasporesmall-spore associations developed within similar lithofacies. On this basis transitional marine, bay-fill and delta-plain deposition are defined in the cored section. These comparative data suggest that the dispersal of megaspore and miospore host floras occurred effectively across the Mid North Sea High, and that they colonized the same niche habitats associated with bay-fill and delta-plain development. © 2016 The Author(s). Published by The Geological Society of London for The Micropalaeontological Society.
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Agglutinated foraminifera are described from Middle to Upper Jurassic sediments of the North Viking Graben region with reference to UKCS Well 211/12-1 (Magnus Field). Four microfaunal associations are determined within the Bathonian to Lower Volgian sequence, and these are shown to relate to regional biofacies developments within the East Shetland Basin and North Viking Graben. Ten major bioevents among the assemblages of agglutinated foraminifera are correlated between wells 211/12–1 and 211/18a-21 (Don Field), providing a detailed stratigraphic framework for the interpretation of complex syn-rift packages.
Article
The base of the Aalenian stage is taken as the base of the M.Jurassic and the base of the Oxfordian stage as the base of the U.Jurassic. The development of the M. and U.Jurassic rocks in the British Isles is illustrated in the correlation charts which are amplified by the text. The Aalenian and Bajocian stages are treated on one chart, but there are separate charts for the Bathonian, Callovian, Oxfordian, Kimmeridgian and Portlandian Stages. The latter is preferred as a name for the terminal Jurassic Stage of the Boreal Province.-from Authors
Article
Ostracods are very useful for dating and correlating Callovian to Ryazanian strata in the Dutch Central North Sea Graben. Although the presence and abundance of these benthic animals are dependent on ecology, individual species' ranges are in most cases limited. Moreover, some endemic forms, with a highly restricted occurrence in time, are excellent index fossils. This paper has the form of an atlas and is intended for practical stratigraphical work in the Central North Sea Graben and adjacent areas. Eight-nine species, nine of which new, are described and amply illustrated. -Authors
Article
Jurassic rocks have provided the basis for many stratigraphical concepts, and the development of these rocks in Britain is amongst the finest in the world. The introductory sections summarize the current position of stratigraphical practice in the Jurassic. There follows a new recommendation for the base of the Jurassic System in Britain. Distribution of Jurassic rocks on land and in the offshore basins leads on to the charts with explanatory notes showing the correlation of onshore successions for the Hettangian-Toarcian Stages at outcrop and in boreholes.- Authors
Article
The microfloras of the marine Neill Klinter, Vardekloft, and lower Hareelv Formations have been investigated from exposures in the Vardekloft ravine at Hurry Inlet, eastern Jameson Land. The samples have yielded abundant spores and pollen as well as dinoflagellate cysts. Based on the occurrence of spores and pollen four microfloral assemblages (A-D) have been established. Biostratigraphic correlations based on the dinoflagellate occurrences as well, have been proposed by comparison with microfloras of Europe. Assemblage A and B of the Neill Klinter Formation have been correlated to (Late) Pliensbachian to Early Toarcian. The typical assemblage C microfloras are restricted to the Vardekloft Formation and is correlated to the Middle-Late Bajocian at the base of the formation and to the (Early) Callovian at the top. The assemblage D has been recovered from the lower Hareelv Formation. Based on the dinoflagellate cysts the deepest samples available from this formation may be correlated to the Oxfordian cordatum(-plicatilis) Zone while the upper part of the section in Vardekloft is referred to the Early Kimmeridgian. The composition of the microfloras indicates marine to brackish palaeoenvironments with considerable variations in the terrestrial derived palynomorph groups. Comparison with age equivalent microfloras of Svalbard and Andoya, Northern Norway, and the Middle Europe indicates the stratigraphical distribution of some spores to be palaeolatitudinally controlled. -Authors
Article
On the basis of a study of dinoflagellate cysts from the Jurassic succession, including the Rhaetian and the Ryazanian, of Denmark, it is shown that the lithostratigraphic units have isochronous boundaries in the central part of the basin but are diachronous towards the paleocoast at the margin of the Baltic Shield. The study demonstrates that the Jurassic section is more complete in the central part of the basin than previously thought and that the hiatuses reported from the base and top of the Middle Jurassic Haldager Sand Formation are shown to be relatively insignificant, in contrast to earlier work. With respect to paleoenvironment, the dinoflagellate data show variable distribution patterns that can be related to the paleoecological coast-oceanic trend, i.e. to the inner neritic-coastal shelf, and the middle-outer neritic or shelf part of the basin. Periods with restricted marine conditions have also been recognized and the sea-level fluctuations at the end of the Jurassic are reflected in the changing dinoflagellate cyst assemblages. The macrofossil records and the ostracod zonation for the Jurassic of Denmark have formed the basis for succeeding biostratigraphic investigations using spores and pollen, and for this study on dinoflagellate cysts. These earlier biozonations are reviewed to describe the biostratigraphic foundation for this study. Investigation of Late Jurassic dinoflagellate cysts from ammonite-dated samples from Poland has made it possible to correlate the British-Danish zonation for the Late Jurassic with other European ammonite-dated sections. This comparison demonstrates that some of the chronostratigraphic units from the areas in question may be correlated somewhat differently from earlier practice. The Kimmeridgian mid-Divisum Zone of Poland correlates with the mid-Mutabilis Zone of Britain. The lower part of the Volgian Scythicus Zone of Poland is here correlated with the Albani Zone of Britain and Denmark. Nine new species of dinoflagellate cysts (Aldorfia warringtonii, Apteodinium daveyi, Batioladinium matyjae, Cometodinium jurassicum, Cribroperidinium hansenii, Dichadogonyaulax? brenneri, Nannoceratopsis raunsgaardii, Occisucysta wierzbowskii and Tubotuberella owensii), together with a new subspecies of dinoflagellate cysts (Neuffenia willei subsp. lanterna), and two new species of acritarchs (Fromea thomsenii and Schizocystia lundii). The genus Acanthaulax is considered a junior synonym of Cribroperidinium. Cribroperidinium caudum and Cribroperidinium systremmatum are regarded as synonyms of Cribroperidinium globatum. Some species of the genus Muderongia are discussed and new combinations and re-attributions are proposed. A neotype for Dingodinium tuberosum is designated and the species is compared with other species of Dingodinium. Several Jurassic psilate species of Escharisphaeridia are treated as synonyms of Escharisphaeridia psilata. Netrelytron is considered as a junior synonym of Kalyptea, and Netrelytron stegastum, Netrelytron parum and Netrelytron trinetron are considered as synonyms with Kalyptea stegasta, the senior name. The genus Nannoceratopsis is divided into three complexes: (1) Senex-complex, species with smooth or microgranular autophragm, (2) Gracilis-complex, species with smooth or microgranular autophragm and perforate ectophragm, (3) Spiculata-complex, species with microvermiculate autophragm. The genera Systematophora, Perisseiasphaeridium, and Amphorula are discussed as a complex. https://palynologyshop.org/product/contribution-series-number-31/
Chapter
Faulting activities during the Mesozoic strongly affected the development of basins in the northeastern North Sea. Before the Kimmeridgian, fair ostracod correlation exists between the Danish Sub-basin and the Polish-German basins. During the Volgian and Neocomian, fair correlation exists between the Danish Sub-basin and the English basins. A North Sea-Arctic Seaway during the Jurassic and Lower Cretaceous, probably into lowermost Tertiary, seems to have some controlling effects on deposition and fossil content in the North Sea area. Mandelstamia and Galliaecythereidea, characteristic genera for the boreal seas, undergo strong differentiation. Macrodentina developed in more restricted environments. In shallow areas and in ages with a strong influx of warm surface water, Cytherelloidea, Bairdia, Protocythere and related genera occur. Zone index species ought to be selected from among a few genera.
Chapter
The Tarbert and Hugin Formations (mainly Bajocian/Bathonian to Callovian) of the northern North Sea were formed in the overall transgressive phase of the Brent/Vestland Group megasequence. Detailed correlation of c25 wells in the Norwegian sector reveals a composite pattern of transgressive-regressive (T-R) depositional sequences in these formations. The depositional sequences are identified on the basis of wireline logs and sedimentological core descriptions. Sequence boundaries are defined based on allostratigraphic (NACSN, 1983) principles. A framework of palynological events is established and used as support for the sequence correlation between the wells. The T-R depositional sequences are composed of a thin transgressive unit (sometimes lacking), and a regressive (progradational and aggradational) unit forming the main portion of the sequence. They typically span 1-2 Ma and so compare with the third-order cycles of Vail et al. (1977). The regressive units reflect progradation (generally northward) and aggradation of tidally influenced shoreline complexes, backed by tidal inshore systems and coal-forming coastal plains (Ness/Sleipner Formation). In an offshore direction, marine silts and muds were deposited (Heather Formation). -from Authors
Chapter
Foraminiferal distribution data have been used for stratigraphic zonation of a c. 230 m thick sedimentary series comprising the Agardhfjellet and basal Rurikfjellet formations (Callovian to Ryazanian) in central Spitsbergen. The dominant lithologies are organic-rich shales, but siltstones and silty shales with intermediate and low organic content also occur. The faunas consist almost exclusively of agglutinated taxa, with significant amounts of calcareous forms restricted to a single (Ryazanian) horizon. Altogether, 44 agglutinated and 10 calcareous (Lagenid) species are recorded. The faunal succession is subdivided into eight zones. Age assignments of these are based on regional correlations of foraminiferal occurrences, and macrofaunal associations. The proposed foraminiferal zones include: (1) Trochammina rostovzevi Zone — Callovian; (2) Recurvoides disputabilis Zone — Oxfordian; (3) Haplophragmoides canuiformis Zone — Lower and Upper Kimmeridgian; (4) Trochammina rosacea Zone — uppermost Kimmerid-gian and Lower Volgian; (5) Ammodiscus zaspelovae Zone — Middle Volgian; (6) Trochammina aff. abrupta Zone — Middle and Upper Volgian; (7) Recurvoides obskiensis Zone — Upper Volgian and lowermost Ryazanian; (8) Gaudryina aff. milleri Zone — Ryazanian. Spitsbergen and other areas of the Boreal Realm (western Siberia, the northern North Sea, Sverdrup Basin and western Canada) show an increased development of agglutinated assemblages in Middle Jurassic to Early Cretaceous time. Regionally reduced availability of calcium carbonate associated with locally stagnant conditions are considered critical for this development.
Article
Facies belts exhibit a back-stepping trend towards the London Brabant/ Rhenish Massif through the Early Cretaceous. The overall eustatic sea-level rise was punctuated by short-term tectonic events identified either as localised or North Sea wide in extent. The biostratigraphically constrained sequences have, for the first time, allowed a detailed calibration of tectonic and eustatic events on a North Sea scale. The most extensive database available to any North Sea Cretaceous study was available to the authors together with a comprehensive suite of new high-resolution biostratigraphy and sedimentology. This has allowed unique insights into provenance, depositional environment, extent of sequence stratigraphical events and the degree to which unconformities have been tectonically accentuated.
Article
The Lower Jurassic sequence and ostracods from 36 borings within the Danish Embayment are analysed and described.Hettangian, Sinemurian and Pliensbachian are demonstrated on the basis of extensive ostracod faunas, whilst only weak indications of Aalenian have been found.The following ostracod zones are defined as a basis for a biostratigraphical subdivision of the Lower Jurassic series in the Danish Embayment:The Ogmoconchella adenticulata - Nanacythere (Nanacythere) simplex Zone (Upper Pliensbachian).The Ogmoconchella danica Zone (Upper Sinemurian and Lower Pliensbachian).The Gramannella apostolescui - Kinkelinella (Klinglerella ) foveolata Subzone (Lower Pliensbachian).The Progonoidea reticulata Subzone (lowest Upper Sinemurian, Lias Beta-1a).The Cristacythere betzi - C. crassireticulata Zone (upper Lower Sinemurian).The Ogmoconchella aspinata Zone (Hettangian and lower Lower Sinemurian).The chronostratigraphical subdivision of the Lower Jurassic sequence in the Danish Embayment is presented, based upon the ostracod faunas described here and upon previous investigations of sediments, foraminifera and megafossils.The conditions prevailing in the basin are discussed, with descriptions of the sedimentary and faunal developments, and an evaluation of the relationships with other parts of the Northwest European area.124 ostracod species are described; 23 are described as new, whilst 30 species which cannot be referred to any known species are described with open nomenclature owing to limited or badly preserved material. The remaining 71 species have all been described previously and are more or less well-known. The 124 species fall into 27 genera or subgenera, of which 2 genera (Pseudomacrocy pris and Cristacythere) and 1 subgenus (Nanacythere (Goniocythere)) are established as new.A subdivision is made of the described Lower Jurassic "Procytheridea". The genus Klinglerella Anderson, 1964 is placed as a subgenus under Kinkelinella Martin, 1960. Pleurifera Gramann, 1962 and Progonoidea Gramann, 1962 are regarded as independent genera placed together with Kinkelinella and the new genus Cristacythere.The family Healdiidae is regarded as being represented by only three genera in the Lower Jurassic: Ogmoconcha, Ogmoconchella and Pseudohealdia. The Ontogenetic development of the muscle scar area in Ogmoconchella is shown to be a development from a simple muscle scar of the Pseudohealdia-type to a typical Ogmoconchella-scar.ree genera in the Lower Jurassic: Ogmoconcha, Ogmoconchella and Pseudohea!dia. The Ontogenetic development of the muscle scar area in Ogmoconchella is shown to be a development from a simple muscle scar of the Pseudohea/dia-type to a typical Ogmoconchella-scar.
Article
While palynostratigraphy has been applied to all Norske Shell's exploration wells since the early 1960s, the discovery of the Troll and Draugen fields led to a new phase in palynological applications, with palynology being extensively used in the determination of the reservoir units. Examples of such applications illustrate the following: 1) in the Upper Jurassic Sognefjord Formation in the Troll Field, how integration of palynostratigraphy with event stratigraphy based on blade-shaped opaque palynodebris and on lignite has helped to solve correlation problems; 2) in the Upper Jurassic of both the Troll and Draugen fields, how problems related to reworking have been avoided by preferentially using base occurrences of taxa, event though the relative abundance of the reworked assemblage would initially suggest otherwise; 3) in the Upper Jurassic of the Draugen Field, how palynofacies has helped to determine various sub-environments in the offshore bar sands of the Rogn Formation. The preferential use of base-occurrences in zonation is both theoretically and practically a better approach to biostratigraphic correlation. -Author
Article
The Hettangian to Sinemurian (Lower Jurassic) succession has been investigated for its ostracod fauna. The marine assemblages from this part of the Lower Jurassic succession are of low diversity, dominated by the genus Ogmoconcha Triebel, 1941. The stratigraphical distribution of the known taxa, although distinctive, do not appear to provide a diagnostic tool for recognition of the base of the Sinemurian Stage. The data generated by this work do, however, provide additional evidence that the East Quantoxhead succession is a suitable GSSP for the base of the Sinemurian Stage.