•Tunisian Paleocene–Eocene phosphorites occur in three distinct basinal areas.•Deposits in each area have distinct geochemical signatures.•Commercial phosphorite deposits in the Gafsa-Metlaoui Basin are of Paleocene–Eocene boundary age.•The phosphorites accumulated in high productivity coastal upwelling environments.•Phosphorite deposition accompanied Paleocene-Eocene climate warming.The Late Paleocene–Early Eocene phosphorites of the Metlaoui Group in Tunisia are a world-class phosphate resource. We review the characteristics of phosphorites deposited in three areas: the Northern Basins; Eastern Basins; and Gafsa-Metlaoui Basin. Comprehensive new bulk rock elemental data are presented, together with complementary mineralogical and mineral chemical results. Carbonate fluorapatite (francolite) constitutes the dominant mineral phase in the deposits. Phosphorite samples are enriched in Cd, Sr, U, rare-earth elements and Y, together with environmentally diagnostic trace elements that provide detrital (Cr, Zr), productivity (Cu, Ni, Zn) and redox (Mo, V) proxies. Suboxic bottom-water conditions predominated, with suboxic to anoxic porewaters accompanying francolite precipitation. Phosphorite deposition occurred under increasingly arid climate conditions, accompanying global Paleocene–Eocene warming. The Northern Basins show the strongest Tethys Ocean influence, with surface seawater rare-earth element signatures consistently developed in the phosphorites. Bed-scale compositional variation indicates relatively unstable environmental conditions and episodes of sediment redeposition, with varying detrital supply and a relatively wet local climate. Glauconitic facies in the Northern Basins and the more isolated evaporite-associated phosphorites in the dryer Eastern Basins display the greatest diagenetic influences. The phosphorite – organic-rich marl – diatom-bearing porcelanite facies association in the Gafsa-Metlaoui Basin represents the classic coastal upwelling trinity. Modified Tethyan waters occurred within the Basin during phosphorite deposition, with decreasing marine productivity from NW to SE evidenced by systematically falling enrichment factors for Cu, Ni, Cd and Zn in the phosphorites. Productivity declined in concert with increasing basin isolation during the deposition of the commercial phosphorite beds in the latest Paleocene to earliest Eocene. This isolation trend was temporarily reversed during an episode of maximum flooding associated with the earliest Eocene Paleocene–Eocene Thermal Maximum (PETM).

Results are presented here for the first chalk-based, high-resolution quantitative study of organic-walled dinoflagellate cysts (dinocysts) from the entire Coniacian–Santonian Chalk successions in east Kent and on the Isle of Wight. The lithostratigraphy and dinocyst records (137 taxa) of seven sections are presented, and the stratigraphic ranges of taxa are constrained relative to stage and zonal boundaries, located using extensive macrofossil data. Results are integrated with a previous complementary study of the Isle of Wight Santonian to test and refine existing dinocyst bioevent schemes. Sixteen dinocyst events are proposed as a sequence of biostratigraphic datum levels for the lower Coniacian to uppermost Santonian which, based on average sedimentation rates, represent an average temporal resolution of around 360 kyr. The event stratigraphy forms a basis for the first high-resolution correlation study of quantitative dinocyst data from the Upper Cretaceous of NW Europe. A new genus Culversphaera Prince, Jarvis, Pearce et Tocher gen. nov. is proposed with the new combination Culversphaera velata Prince, Jarvis, Pearce et Tocher gen. et comb. nov. Five new species: Ellipsodinium membraniferum Prince, Jarvis, Pearce et Tocher sp. nov., Senoniasphaera macroreticulata Prince, Jarvis, Pearce et Tocher sp. nov., Senoniasphaera whitenessii Prince, Jarvis, Pearce et Tocher sp. nov., Xenascus spinatus Prince, Jarvis, Pearce et Tocher sp. nov. and X. yunii sp. nov., and the new subspecies S. protrusa congrensa Prince, Jarvis, Pearce et Tocher subsp. nov. are described.

•New dinocyst records and CIEs provide a basis from high-resolution correlation.•A northern European dinocyst event stratigraphy with 22 datum levels is developed.•A revised dinocyst zonation scheme is proposed for the Turonian Stage.Organic walled dinoflagellate cyst (dinocyst) assemblage data are presented for a new Turonian regional reference core (Bch-1) drilled at Běchary in the Bohemian Cretaceous Basin, east-central Czech Republic. The detailed stratigraphic framework for the section is summarised based on calcareous nannofossil and macrofossil biostratigraphy, regional e-log correlation, sequence stratigraphy and carbon isotope chemostratigraphy. Dinocyst results obtained for 196 samples from the 405 m long core offer the highest resolution (~ 22 kyr) stratigraphically well-constrained data set available to date for the Turonian Stage, 93.9–89.8 Ma. A dinocyst biostratigraphic framework is presented based on the evolutionary first and last occurrence, first common occurrence, and acmes of key species. Published dinocyst data from English Turonian Chalk successions in East Sussex, Berkshire, Kent and Norfolk are reviewed within a stratigraphic framework provided by macrofossil records and carbon isotope event (CIE) chemostratigraphy. Critical analysis of existing published Turonian dinocyst zonation schemes shows them to be untenable. Correlation of the English Chalk data to Bch-1 provides a basis for defining a regional dinocyst event stratigraphy with 22 datum levels, and a revised dinocyst zonation scheme constrained within a chemostratigraphic framework of 10 major CIEs. The new zones consist of a Cenomanian Litosphaeridium siphoniphorum Zone, followed by the Cauveridinium membraniphorum Zone spanning the uppermost Cenomanian to Lower Coniacian. This is subdivided into: Senoniasphaera turonica (Lower–mid-Middle Turonian); and Raetiaedinium truncigerum (mid-Middle Turonian–mid-Lower Coniacian) subzones. The Oligosphaeridium pulcherrimum Zone (Senonisphaera rotundata Subzone) characterises the Lower Coniacian. The new stratigraphy offers a basis for improved correlation and dating of Upper Cretaceous successions.

Standard processing techniques for the isolation of organic walled dinoflagellate cysts from geological samples are examined, with particular attention to the size and type of sieve mesh used. Variations within the ‘standard’ processing techniques used by different laboratories are identified, and an assessment of the retention capacities of meshes of different sizes and different materials is carried out. Some dinoflagellate cysts and large numbers of Lycopodium spores, used for the calculations of absolute abundance data, were found to pass through 20 μm meshes. This is due to a combination of factors including: the diagonal aperture diameter of a 20 μm mesh measuring over 28 μm; the three-dimensional properties of different mesh weaves (nylon and polyester); and the non-spherical shape of the particles. Experiments demonstrate that the maximum mesh size that should be used in palynological processing is 15 μm. Nylon mesh is more practical to use than polyester as processing time is reduced, but nylon is degraded by contact with acid solutions. Meshes with apertures < 15 μm may be used, though this may be impractical for large samples containing significant quantities of fine siliciclastic or organic material.