Poul Schiøler

Dinoflagellate biostratigraphy and sequence stratigraphy of the Type Maastrichtian (Upper Cretaceous), ENCI Quarry, The Netherlands

Abstract The upper Maastrichtian strata in ENCI Quarry contain rich assemblages of marine palynomorphs, especially dinoflagellate cysts. A quantitative study shows that a marked change from dinoflagellate-dominated assemblages to assemblages dominated by the acritarch genus Paralecaniella occurs at the base of the Lanaye Member, indicating a change from open marine to marginal marine conditions. A sequence stratigraphic breakdown into systems tracts based on an interpretation of the changes in the palynological assemblages and lithology suggests the presence of parts of four sedimentary cycles in the ENCI section. Three of the cycles may be correlated with the third-order cycles UZA 4.5, TA 1.1 and TA 1.2 of Haq et al. (1988), the fourth cycle is probably of higher order. Three dinoflagellate cysts are new: Laciniadinium? aquiloniforme Schioler et al., sp. nov., Leberidocysta? verrucosa Schioler et al., sp. nov. and Pulchrasphaera minuscula Schioler et al., gen. et sp. nov. The description of Rottnestia wetzelii is emended and the new combination Cribroperidinium wilsonii (Slimani) Schioler et al., comb. nov. is proposed. The Triblastula utinensis Zone, Isabelidinium cooksoniae Zone and the Palynodinium grallator Zone with its two subzones, Tanyosphaeridium magdalium Subzone and Thalassiphora pelagica Subzone can be recognized in the ENCI section.

Maastrichtian dinoflagellate zonation in the Dan Field, Danish North Sea

Abstract Core samples from the Maastrichtian oil reservoir chalks in the Dan Field (southern part of the Danish Central Trough) have yielded diverse dinoflagellate cyst assemblages which have been assessed in order to establish a high-resolution biostratigraphical framework. Eight successive downhole events occur in a relatively consistent pattern and have been used to subdivide the Late Maastrichtian and the late Early Maastrichtian in the Dan Field. The events are: (1) (Cretaceous/Tertiary boundary) Last occurrence datum (LOD) of several taxa: Palynodinium grallator, Spiniferites ramosus cavispinosus, “Chytroeisphaeridia everricula” and “Northidinium perforatum” . (2) First appearance datum (FAD) of P. grallator . (3) FAD of Hystrichostrogylon borisii . (4) LOD of Isabelidinium cooksoniae . (5) The almost simultaneous FAD of Deflandrea galeata and LOD of Triblastula utinensis . (6) LOD of Alterbidinium acutulum . (7) LOD of Eatonicysta hapala sp. nov. (8) FAD of T. utinensis . Four new zones and three new subzones are established below the Palynodinium grallator Zone: Hystrichostrogylon borisii Zone; Palaeocystodinium denticulatum Zone; Isabelidinium cooksoniae Zone; Triblastula utinensis Zone; Cannosphaeropsis utinensis Subzone; Alterbidinium acutulum Subzone; Eatonicysta hapala Subzone. A new stratigraphically important dinoflagellate species, Eatonicysta hapala sp. nov., is formally described. The new subdivision of the oil reservoir chalks had added to the understanding of the extent of the thin high-porosity layers, which are important for oil production from the field.

Age and provenance of Cretaceous marine reptiles from the South Island and Chatham Islands, New Zealand

Abstract Analyses of dinoflagellate cysts from marine reptile sites in Marlborough, North Canterbury, North Otago, and on Chatham Island, indicate that the localities range from Early to latest Haumurian (Middle Campanian to Upper Maastrichtian) in age, spanning a period of c. 15 m.y. Sites in the Waipara River area are principally Upper Haumurian and range from the Alterbidinium acutulum Zone to the Manumiella druggii Zone. Sites in the Haumuri Bluff‐Ngaroma Station‐Cheviot/Jed River area are Lower Haumurian to lower Upper Haumurian and range from the Satyrodinium haumuriense Zone to the Isabelidinium pellucidum Zone. The Shag Point locality is Upper Haumurian (Alterbidinium acutulum Zone), indicating a general correlation with the Waipara localities. The Chatham Island locality is Lower Haumurian (S. haumuriense Zone), indicating a similar age to the oldest Haumuri Bluff sites. Material from two unknown sites appears to be from the Waipara River area, based on the associated dinoflagellate assemblages. Two marine reptile faunas are indicated: a Mid‐Campanian to Early Maastrichtian fauna that is replaced by a Late Maastrichtian fauna.

Palynofacies and sea-level changes in the Middle Coniacian–Late Campanian (Late Cretaceous) of the East Coast Basin, New Zealand

Abstract A palynofacies analysis of four sections through the Paton and Herring Formations of the East Coast Basin in southern Marlborough indicates that the two formations were deposited on the inner to mid-shelf in a marine environment with conspicuous input of plant material from adjacent land area. The Paton Formation was deposited on the inner to mid-shelf under oxic conditions and in proximity to a river delta, possibly in a deltafront setting. Its lower part is clearly less marine than its upper part, pointing to an overall deepening trend with time. The deposition of the Herring Formation took place farther offshore, on the mid-shelf, in a mud-dominated environment under poorly oxygenated conditions at the sediment/water interface, following a landward shift of shoreline. A stratigraphic analysis of changes in palynofacies and lithology through the four sections allows a breakdown of the succession into seven depositional sequences, separated by unconformities or their correlative conformities. A regional sea-level curve for the Middle Coniacian–Upper Campanian in the East Coast Basin is proposed on the basis of the inferred sequences and chronostratigraphic control from dinoflagellate biostratigraphy. The sea-level cycles thus inferred for the East Coast Basin show a poor correlation with the re-scaled Haq cycle chart, suggesting that regional tectonics rather than eustasi controlled the East Coast Basin sequences.

Detection of Late Cretaceous eustatic signatures using quantitative biostratigraphy

This study tested the potential for high-resolution quantitative biostratigraphic methods to distinguish tectonic from supposedly eustatic sequences. The study employed automated multidimensional graphic correlation using constrained optimization (program CONOP). Our analysis was based on 15 onshore sections in eastern New Zealand spanning the Coniacian to Maastrichtian stages (Upper Cretaceous), and 398 well-constrained lowest- or highest-occurrence records derived from 245 dinoflagellate species. The age of the resulting composite section was calibrated using six dated bioevents; two of these events were tied to geochemical or paleomagnetic datums. Following calibration, the composite section had an average relative temporal resolution of less than 130 k.y. through the study interval, although the succession of events was not dated to this level of precision in an absolute sense. Although the CONOP composite will not resolve unconformities or condensed intervals that occur across all studied sections, such “global” unconformities can be identified using clusters of events that are placed at a single composite level. Fifteen major event clusters were identified, 10 of which coincided closely with sequence boundaries identified in the Northern Hemisphere; the probability of this coincidence arising by chance alone is ∼8%. Although these results must be regarded as provisional, they suggest that high-resolution quantitative stratigraphy can provide a potent tool for the identification and correlation of stratigraphic sequences. Furthermore, our findings add significant support for recent studies that have argued for the presence of Late Cretaceous eustasy.

Dinoflagellate biostratigraphy of the middle Coniacian-lower Campanian (Upper Cretaceous) in South Marlborough, New Zealand

The dinoflagellate distribution in two Teratan-lower Haumurian (Coniacian-Campanian) sections at Ben More Stream and Kekerengu River (south Marlborough, New Zealand) is documented and discussed, and a new zonation scheme proposed. The Conosphaeridium striatoconum Zone of Wilson (1984) and the Odontochitina porifera Zone of Wilson (1984) are proposed as new Superzones. The C. striatoconum Superzone is subdivided into three new zones: Cymososphaeridium benmorense Interval Zone and Conosphaeridium abbreviatum Interval Zone. Four Australian dinoflagellate zones are recognized in the sections: Odontochitina porifera Interval Zone of Helby et al. (1987), Isabelidinium cretaceum Zone of Evans (1971), Nelsoniella aceras Zone of Evans (1971) and Satyrodinium haumuriense Zone of Marshall (1990). A correlation of the two sections with international stages based on key dinoflagellates and supported by previous work on inoceramid bivalves dates the sections as middle Coniacian to Campanian. The Teratan-Piripauan stage boundary can be placed in the uppermost Coniacian and the Piripauan-Haumurian stage boundary in the upper Santonian. Six new dinoflagellate species are present in the sections: Batiacasphaera kekerengensis n.sp., Batiacasphaera rugulata n.sp., Cymososphaeridium benmorense n.sp., Eucladinium kaikourense n.sp., Glaphyrocysta marlboroughensis n.sp. and Kleithriasphaeridium secatum n.sp.

Dinoflagellate cysts and acritarchs from the Oligocene–Lower Miocene interval of the Alma-1X well, Danish North Sea

This palynological study of cuttings samples from the Lark Formation in the Danish North Sea well Alma-1X documents for the first time in the public domain the succession of last occurrences of dinoflagellate cysts and acritarchs in the Oligocene–Lower Miocene interval of the Central North Sea. The distribution of dinoflagellates and acritarchs in the well demonstrates the potential for the development of a detailed subdivision of the Oligocene–Lower Miocene in the Central North Sea, based on the first downhole occurrences of key taxa. Five regional intra-Lark Formation seismic and petrophysical log markers can be dated with precision using dinoflagellate biostratigraphy. Four new species and one new subspecies of dinoflagellates are described from the study interval: Amphorosphaeridium? almae sp. nov., Filisphaera pachyderma sp. nov., Pentadinium corium sp. nov., Spiniferites pseudofurcatus verrucosus ssp. nov. and Thalassiphora rota sp. nov. Pseudospiniferites manumii Lund, 2002 is emended and transferred to the genus Spiniferites.

Dinoflagellate cysts from the Arnager limestone formation (coniacian, late cretaceous), Bornholm, Denmark

Abstract Siliceous chalk samples from the Upper Cretaceous Arnager Limestone Formation, Bornholm, Denmark, have yielded diverse dinoflagellate cysts assemblages key taxa from these assemblages indicate an Early to mid-Coniacian age. One new species, Isabelidinium foucherri sp. nov., is described, and the morphology of two dinoflagellate cysts, one possibly belonging to the genus Senoniasphaera and one belonging to the genus Xenascus , is discussed.

New species of dinoflagellate cysts from Maastrichtian-Danian chalks of the Danish North Sea

A palynological study of Danian - Maastrichtian chalks from the Dan oilfield (Danish North Sea) has revealed the presence of nine new species and subspecies of dinoflagellate cysts: Achomosphaera antleriformis sp. nov., Cassiculosphaeridia? tocheri sp. nov., Chlamydophorella? multifibrata sp. nov., Isabelidinium majae sp. nov., Hystrichosphaeropsis perforata sp. nov., Hystrichostrogylon borisii sp. nov., Leberidocysta? flagellichnia sp. nov., Spiniferites foveolatus sp. nov. and Spiniferites pseudofurcatus granulosus ssp. nov. Seven of the taxa are considered important biostratigraphic markers in the area.

Paleoenvironmental and tectonic changes across the Cretaceous/Tertiary boundary at Tora, southeast Wairarapa, New Zealand: A link between Marlborough and Hawke's Bay

Abstract The Late Cretaceous‐Paleocene succession exposed on the Tora coast, near the southeastern tip of the North Island, is distinguished by an unusual lithofacies of the Whangai Formation, and by an apparently unique formation, Manurewa Formation, which spans the Cretaceous/Tertiary (K/T) boundary. The Late Cretaceous siliceous Whangai Formation at Tora includes zones of slumps and olistostromes, containing megaclasts of limestone up to 3 m long. The olistostromal deposits suggest steep submarine topography with a high rate of erosion, and imply tectonic activity. The common occurrence of hummocky cross‐stratification suggests deposition in shelf depths above storm wave base. The sharply overlying Manurewa Formation is interpreted as the infill of a major shallow channel complex, perhaps >9 km wide and spanning the K/T boundary in time. The older of two channelled units is of latest Cretaceous (latest Haumurian/late Maastrichtian) age, and consists of bioturbated alternating thin sandstone and mudstone with thin conglomerate lenses and limestone beds. It is likely to have been deposited in a low‐energy environment, probably deeper than that of the Whangai. The younger channel system, of early Paleocene (early Teurian) age, erodes into the older in the northeast, and into the underlying Whangai Formation in the southwest. Basal deposits consist predominantly of medium to coarse, thick‐bedded, glauconitic sandstone, with local low‐angle cross‐stratification and microflora typical of low salinity conditions, suggesting deposition in shallow shelf depths. These deposits contain olistrostromes with megaclasts up to 1 m long of limestone and rarer dark grey siltstone or very fine sandstone clasts typical of Whangai Formation. The inclusion of megaclasts of Whangai Formation indicates that local emergence and erosion of older strata was occurring. Deposits grade upward into well‐sorted bioturbated sandstones of the Awhea Formation, with prominent low‐angle cross‐stratification, interpreted as very shallow marine, probably nearshore deposits. The channel system represented by the Manurewa Formation records an initial relative sea‐level rise, followed by an abrupt sea‐level fall at, or close to, the K/T boundary. New Zealand was in a passive margin tectonic setting at the time, but the widespread presence of olistostromes, some including clasts derived from older strata, suggest that local tectonic activity and uplift was occurring. The effects may have been enhanced by a climatic shift in storm tracks and intensity in the latest Cretaceous, which is supported by the evidence of strong wave activity. By contrast, to the south in Marlborough, the K/T boundary succession is commonly characterised by an apparently conformable lithologic change from limestone to chert, although with local hiatus. To the north, in southern Hawkes Bay, the coeval succession is characterised by a disconformity separating greensand from underlying light grey, slightly calcareous mudstone of the Whangai Formation. The Tora sequence may provide the link between two distinctly different lithologic successions.