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Over the last four decades, organic-walled dinoflagellate cysts have shown high potential as tracers of past sea-surface conditions during the Quaternary. These microfossils relate to the pelagic productivity of both phototrophic and heterotrophic protist organisms and are recovered in high numbers in almost all marine environment settings from the nearshore and estuarine systems to the distal continental margin. In polar environments, where other conventional proxies are rare or absent, dinoflagellate cysts showed a relatively high diversity of species and a close relationship with sea-ice cover duration, winter and summer temperature, and salinity, enabling quantitative reconstructions of several oceanic variables over time. From the temperate to the tropical latitudes of the Atlantic Ocean, their modern distribution highlights a response to primary productivity and seasonal contrasts in surface temperature. They also have proven that they could be used as tracers of eutrophication in stratified systems and can also highlight human impact on their distribution. In this paper, we present an overview of dinoflagellate cysts as ecological tracers in recent and past sediments of the Atlantic Ocean, from the Arctic to the Antarctic. We provide examples of their use as proxies in paleoclimatic-palaeoceanographic studies at glacial to interglacial time scales, with emphasis on the last ice age to recent (last 25 kyr), the northern North Atlantic and western-eastern tropic North Atlantic. We also discuss their potential as tracers of anthropogenic stress in coastal environments. [ABSTRACT FROM AUTHOR]

Instrumental records from the Norwegian Sea and the Trondheimsfjord show evidence that changes of bottom water temperature and salinity in the fjord are linked to the salinity and temperature variability of the North Atlantic Current (NAC). Changes in primary productivity and salinity in the surface and intermediate water masses in the Trondheimsfjord as well as the fjord sedimentary budget are mainly driven by changes in riverine input. In this study we use 59 surface sediment samples that are evenly distributed in the fjord to examine whether dinocyst assemblages and stable isotope ratios of benthic foraminifera reflect the present-day hydrology and can be used as paleoceanographic proxies. In general, modern benthic δ18O and δ13C values decrease from the fjord entrance towards the fjord head with lowest values close to river inlets. This is essentially explained by gradients in the amounts of freshwater and terrigenous organic matter delivered from the hinterland. The distribution of benthic δ13C ratios across the fjord is controlled by both the origin (terrigenous vs. marine) of organic matter and local topography-induced variability in organic matter flux at the water-sediment interface. The dinocyst assemblages display the variations in hydrography with respect to the prevailing currents, the topography, and the freshwater and nutrient supply from rivers. The strength and depth of the pycnocline in the fjord strongly varies seasonally and thereby affects water mass characteristics as well as nutrient availability, temporally creating local conditions that explain the observed species distribution. Our results prove that dinocyst assemblages and benthic foraminiferal isotopes reliably mirror the complex fjord hydrology and can therefore be used as proxies of Holocene climatic variability. [ABSTRACT FROM AUTHOR]

We analysed dinoflagellate cyst assemblages in four short sediment cores, two of them dated by radionuclides, taken in the south basin of the Caspian Sea. The interpretation of the four sequences is supported by a collection of 27 lagoonal or marine surface sediment samples. A sharp increase in the biomass of the dinocyst occurs after 1967, especially owing to Lingulodinium machaerophorum. Considering nine other cores covering parts or the whole of Holocene, this species started to develop in the Caspian Sea only during the last three millennia. By analysing instrumental data and collating existing reconstructions of sea level changes over the last few millennia, we show that the main forcing of the increase of L. machaerophorum percentages and of the recent dinocyst abundance is global climate change, especially sea surface temperature increase. Sea level fluctuations likely have a minor impact. We argue that the Caspian Sea has entered the Anthropocene. [ABSTRACT FROM AUTHOR]

Dinoflagellate cyst (dinocyst) assemblages have been widely used over the Arctic Ocean to reconstruct sea-surface parameters on a quantitative basis. Such reconstructions provide insights into the role of anthropogenic vs natural forcings in the actual climatic trend. Here, we present the palynological analysis of a 36 cm-long core collected from the Mackenzie Through in the Canadian Beaufort Sea. Dinocyst assemblages were used to quantitatively reconstruct the evolution of sea surface conditions (temperature, salinity, sea ice) and freshwater palynomorphs influxes were used as local paleo-river discharge indicators over the last ∼ 150yr. Dinocyst assemblages are dominated by autotrophic taxa (68 to 96%). Pentapharsodinium dalei is the dominant specie throughout most of the core, except at the top where the assemblages are dominated by Operculodinium centrocarpum. Quantitative reconstructions of sea surface parameters display a serie of relatively warm, lower sea ice and saline episodes in surface waters, alternately with relatively cool and low salinity episodes. The warm episodes are characterized with high dinocyst productivity. Variations of dinocyst influxes and reconstructed sea surface conditions are closely linked to large scale atmospheric circulation patterns such as the Pacific Decadal Oscillation (PDO) and to a lesser degree, the Arctic Oscillation (AO). Positive phases of the PDO correspond to increases of dinocyst influxes, warmer and saltier surface waters, which we associate with upwelling events of warm and relatively saline water from Pacific origin. Freshwater palynomorph influxes increased in three phases from AD 1857 until reaching maximum values in AD 1991, suggesting that the Mackenzie River discharge followed the same trend when its discharge peaked between AD 1989 and AD 1992. The PDO mode seems to dominate the climatic variations at multi-annual to decadal timescales in the Western Canadian Arctic and Beaufort Sea areas. [ABSTRACT FROM AUTHOR]

It is with great pleasure that we introduce palsys.org (https://palsys.org/genus/ , last access: 8 December 2023), a fully open-access taxonomic, stratigraphic and image database of organic-walled dinoflagellate cysts. Palsys.org started as the in-house database of the Laboratory of Palaeobotany and Palynology (LPP) Foundation over 30 years ago. It is now owned by Utrecht University and has been expanded and transformed into a public online platform for use in research and education. Palsys.org includes the taxonomic descriptions of genera and species of organic walled dinoflagellate cysts, from the (often translated) literature, and emendations and synonymy, mainly following Williams et al. (2017) and the stratigraphic calibrations from DINOSTRAT (Bijl, 2022), and has around 25 000 images of species. Here, in this launch paper, we explain the history of the database, present its current functionalities and explain our set-up of the data quality control. We call upon the community to help us keep palsys.org up to date and complete by, for example, by sending additional information, imagery and feedback in general through the platform. Palsys.org brings dinoflagellate micropaleontology in line with the open-science principles of modern academia. [ABSTRACT FROM AUTHOR]

New dinocyst analyses were conducted on core MD99-2339 retrieved from the central Gulf of Cadiz. Dinocyst and foraminiferal assemblages from this core are combined with existing data off SW Portugal and NW Morocco to investigate past hydrological and primary productivity regimes in the subtropical NE Atlantic Ocean over the last 30 ka. Our results have revealed highest upwelling intensity during Heinrich Stadial 1 (HS 1) and the Younger Dryas and weaker upwelling cells during the Last Glacial Maximum and HS 2, off the SW Iberian and NW Moroccan margins. Similar assemblages between Cadiz and Morocco and distinct species off Portugal were observed during the cold climatic extremes that punctuated the last 30 ka. This pattern has been linked to the occurrence of a hydrological structure between SW Iberia and Cadiz during the last glacial period, probably similar to the modern Azores Front. This front was probably responsible locally for heterotrophic dinocysts found in the Gulf of Cadiz during the last glacial period, even if this sector is not conductive to upwelling phenomena by Ekman transport. Regional reconstructions of paleo-sea-surface temperatures using dinocyst and foraminiferal transfer functions, as well as alkenones, are also discussed and depict coherent scenarios over the last 30 ka. However, some mismatches are observed between the different quantitative reconstructions such as during HS 1 in the Gulf of Cadiz and during the LGM at the three core locations. [ABSTRACT FROM AUTHOR]

Deserts are stressful environments where the living beings must acquire different strategies to survive due to the water stress conditions. From the late Albian to the early Cenomanian, the northern and eastern parts of Iberia were the location of the desert system represented by deposits assigned to the Utrillas Group, which bear abundant amber with numerous bioinclusions, including diverse arthropods and vertebrate remains. In the Maestrazgo Basin (E Spain), the late Albian to early Cenomanian sedimentary succession represents the most distal part of the desert system (fore-erg) that was characterised by an alternation of aeolian and shallow marine sedimentary environments in the proximity of the Western Tethys palaeo-coast, with rare to frequent dinoflagellate cysts. The terrestrial ecosystems from this area were biodiverse, and comprised plant communities whose fossils are associated with sedimentological indicators of aridity. The palynoflora dominated by wind-transported conifer pollen is interpreted to reflect various types of xerophytic woodlands from the hinterlands and the coastal settings. Therefore, fern and angiosperm communities abundantly grew in wet interdunes and coastal wetlands (temporary to semi-permanent freshwater/salt marshes and water bodies). In addition, the occurrence of low-diversity megafloral assemblages reflects the existence of coastal salt-influenced settings. The palaeobotanical study carried out in this paper which is an integrative work on palynology and palaeobotany, does not only allow the reconstruction of the vegetation that developed in the mid-Cretaceous fore-erg from the eastern Iberia, in addition, provides new biostratigraphic and palaeogeographic data considering the context of angiosperm radiation as well as the biota inferred in the amber-bearing outcrops of San Just, Arroyo de la Pascueta and La Hoya (within Cortes de Arenoso succesion). Importantly, the studied assemblages include Afropollis, Dichastopollenites, Cretacaeiporites together with pollen produced by Ephedraceae (known for its tolerance to arid conditions). The presence of these pollen grains, typical for northern Gondwana, associates the Iberian ecosystems with those characterising the mentioned region. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This paper presents the diatom and palynomorph data from a sediment trap deployed in the northern part of the East Barents Sea for an annual cycle from August 2017 to August 2018. The average monthly fluxes of diatoms and dinoflagellate cysts in the photic layer of the northeastern part of the Barents Sea varies from 10.4 × 103 to 640.8 × 103 valves m−2 day−1 and from 0.3 × 103 to 90.0 × 103 cysts m−2 day−1, respectively. Their fluxes are related to the low irradiance of the photic layer during the sea-ice cover period, dominance of southward currents, modern climate, and nepheloid layer conditions. Based on redundancy analysis of the relationship between the fluxes of diatoms and dinoflagellate cysts and organic carbon fluxes, sea-ice covers, and the seasonal cycle of light availability we determined the following. First, sea-ice-associated diatoms and dinocysts are exported to the sediment trap from the melting sea ice with a two-week delay. Second, the appearance of freshwater diatoms and green algae in the sinking material accumulating from March 2018 to July 2018 is also related to the melting of sea ice. And third, the presence of Coscinodiscus radiatus, C. perforatus, Shionodiscus oestrupii and Operculodinium centrocarpum in the diatoms and dinocysts species composition throughout the year indicates the advection of Atlantic waters into the Barents Sea up to 80° N. [ABSTRACT FROM AUTHOR]

Many sediment attributes have been proposed as proxies for determining salinity conditions under which sediment is deposited, and six attributes (Sr/Ba-HAc, Sr/Ba-NH4Ac, δ13Corg, C/N, and the relative abundances and concentrations of dinoflagellate cysts) are compared here. In this paper, sediment attributes from the Fraser River Delta, Canada and surrounding coastal areas are compared by depositional position along the fluvial-to-marine transition, by salinity, and by sedimentological characteristics. Along the fluvial-to-marine transition, most attributes exhibit distinct trends between parts of the river that experience sustained marine water (saltwater) influence over seasonal and tidal timeframes, and parts that experience only freshwater or periodic saltwater influence. No attributes are reliable indicators of depositional position where saltwater incursion is short lived or where water is fresh. Where marine influence is sustained, Sr/Ba-HAc and Sr/Ba-NH4Ac are the most reliable positional indicators along the fluvial-to-marine transition. When compared strictly to salinity, Sr/Ba-HAc, Sr/Ba-NH4Ac, and δ13Corg all correlate predictably except in delta front and prodelta settings. Our data show that all six sediment attributes are heavily impacted by river-derived sedimentation, and it is not appropriate to compare values from strongly river-influenced settings (e.g., deltas) with those from weakly river-influenced settings (e.g., bays and estuaries). [ABSTRACT FROM AUTHOR]

Mesozoic–Cenozoic organic-walled dinoflagellate cyst (dinocyst) biostratigraphy is a crucial tool for relative and numerical age control in complex ancient sedimentary systems. However, stratigraphic ranges of dinocysts are found to be strongly diachronous geographically. A global compilation of state-of-the-art calibrated regional stratigraphic ranges could assist in quantifying regional differences and evaluating underlying causes. For this reason, DINOSTRAT is here introduced – an open-source, iterative, community-fed database intended to house all regional chronostratigraphic calibrations of dinocyst events (https://github.com/bijlpeter83/DINOSTRAT.git , last access: 1 February 2022​​​​​​​) (DOI – https://doi.org/10.5281/zenodo.5772616 , Bijl, 2021). DINOSTRAT version 1.0 includes >8500 entries of the first and last occurrences (collectively called "events") of >1900 dinocyst taxa and their absolute ties to the chronostratigraphic timescale of Gradstein et al. (2012). Entries are derived from 199 publications and 188 sedimentary sections. DINOSTRAT interpolates paleolatitudes of regional dinocyst events, allowing evaluation of the paleolatitudinal variability in dinocyst event ages. DINOSTRAT allows for open accessibility and searchability, based on region, age and taxon. This paper presents a selection of the data in DINOSTRAT: (1) the (paleo)latitudinal spread and evolutionary history of modern dinocyst species, (2) the evolutionary patterns and paleolatitudinal spread of dinocyst (sub)families, and (3) a selection of key dinocyst events which are particularly synchronous. Although several dinocysts show – at the resolution of their calibration – quasi-synchronous event ages, in fact many species have remarkable diachroneity. DINOSTRAT provides the data storage approach by which the community can now start to relate diachroneity to (1) inadequate ties to chronostratigraphic timescales, (2) complications in taxonomic concepts, and (3) ocean connectivity and/or the affinities of taxa to environmental conditions. [ABSTRACT FROM AUTHOR]

In the Western Scheldt Estuary near the Belgian-Dutch border, middle to late Eocene strata crop out at the current seafloor. Most vertebrae of large Eocene basilosaurid taxa from this area were previously described in several papers. They represent three morphotypes: elongated vertebrae of a large species of Pachycetus (Morphotype 1b), a not-elongated vertebra of a large ‘dorudontid’ basilosaurid (Morphotype 2) and ‘shortened’ vertebrae of a new, unnamed taxon (Morphotype 3). This article deals with a still undescribed, smaller vertebra, NMR-16642, from this site. Our first aim was to date it by dinoflagellate cysts in adhering sediments. Yielding an age of about 38 Ma, it is one of the very few remains of basilosaurids from Europe, of which the age could be assessed with reasonable certainty. The vertebra, Morphotype 1a, is assigned to a small species of Pachycetus. High-quality CT scans are used to differentiate between NMR-16642, Morphotype 1a, and the large species of Pachycetus, Morphotype 1b. Another aim of this paper is to investigate the inner structure and vascularity of the study vertebra and that of the other morphotypes (1b, 2, 3) from this area by using high-quality CT scans. Notwithstanding differences in size, shape and compactness, the vertebral inner structure with a multi-layered cortex of periosteal bone, surrounding two cones of endosteal bone appears to be basically similar in all morphotypes. Apparently, this inner structure reflects the ontogenetic vertebral growth. An attempt to reconstruct the vascularity of the vertebrae reveals a remarkable pattern of interconnected vascular systems. From the dorsal and, if present, ventral foramina, vascular canals are running to a central vascular node. From this node a system of vascular canals goes to the epiphyseal ends, giving rise to separate systems for cortex and cones. It is the first time that the vascularity of vertebrae of archaeocetes is investigated.

Mesozoic-Cenozoic organic-walled dinoflagellate cyst (dinocyst) biostratigraphy is a crucial tool for relative and numerical age control in complex ancient sedimentary systems. However, stratigraphic ranges of dinocysts are found to be strongly diachronous geographically. A global compilation of state-of-the-art calibrated regional stratigraphic ranges could assist in quantifying regional differences and evaluate underlying causes. DINOSTRAT (Bijl, 2023a; Bijl, 2023b) is an open source, iterative, community-fed database intended to house all regional chronostratigraphic calibrations of dinocyst events DINOSTRAT version 2.0-GTS2020 includes >9,450 entries of first and last occurrences (collectively called "events") of >2,040 dinocyst taxa, and their absolute ties are now updated to the chronostratigraphic timescale of Gradstein et al., 2020. Entries are derived from 211 publications and 209 sedimentary sections. DINOSTRAT interpolates paleolatitudes of regional dinocyst events, allowing evaluation of the paleolatitudinal variability of dinocyst event ages. DINOSTRAT allows for open accessibility and searchability, on region, age, and taxon. This paper presents a selection of the data in DINOSTRAT: (1) the (paleo)latitudinal spread and evolutionary history of modern dinocyst species; (2) the evolutionary patterns and paleolatitudinal spread of dinocyst (sub)families; (3) a selection of key dinocyst events which are particularly synchronous. Although several dinocysts show - at the resolution of their calibration - quasi-synchronous event ages, indeed many species have remarkable diachroneity. DINOSTRAT provides the data storage approach by which the community can now start to relate diachroneity to (1) inadequate tie to chronostratigraphic timescales; (2) complications in taxonomic concepts and (3) ocean connectivity and/or the affinities of taxa to environmental conditions. [ABSTRACT FROM AUTHOR]

The almost complete, mainly deltaic, upper Paleogene and Neogene succession in Jylland, Denmark, was previously investigated for 87Sr/86Sr ratios in 143 samples from 18 localities. In the present paper, strontium-isotope data from the Upper Oligocene-Lower Miocene parts and foraminiferal and pyritised diatoms data from 94 of these samples were used to correlate with previously published data from Norwegian wells and boreholes and one borehole in the British sector of the North Sea. For the Middle-Upper Miocene parts of the succession the correlation is based mainly on Bolboforma data. The ages of the geological formations in the Danish succession correlate readily with lithological units in the Norwegian North Sea, the Norwegian Sea shelf and the East Shetland Platform, which have all been investigated applying similar methods. The Bolboforma assemblages have their origin in the North Atlantic and the Norwegian Sea and confirm the presence of an open strait in the northern North Sea. This strait was the only seaway passage into the North Sea Basin during the Miocene. The glauconitic Utsira Formation sand (approximately 5.7-4.2 Ma), in the threshold area close to the outlet to the Norwegian Sea, overlies erosional unconformities comprising hiati of 21 my in some areas and 13 my in other areas. We believe that the unconformity below the Utsira Formation was mainly related to a fall in sea level in the Late Miocene, contemporaneous with that partly responsible for the Messinian salinity crisis. Bolboforma and dinoflagellate cysts stratigraphy indicate that the base of the Molo Formation in its southern distribution area (Draugen Field, Trøndelag Platform) is of Late Miocene age (close to 9 Ma). This part of the Molo Formation was contemporaneous with the middle/upper part of the Kai Formation. [ABSTRACT FROM AUTHOR]

The coastal area of Qinhuangdao, particularly the Changli Gold Coast Nature Reserve, is experiencing ecological degradation and frequent Harmful Algal Blooms (HABs). This study focuses on the changing phytoplankton communities in these coastal waters, examining them from both a macroscopic and microscopic perspective. Utilizing microscopy, molecular techniques, and pigment analysis, seasonal shifts were observed, with diatoms predominating in June and July, and dinoflagellates in August. Our morphological examination enabled the classification of 89 species into four distinct groups. The species Paralia sulcata and Pseudo-nitzschia pungens were most abundant in early summer, while Tripos furca, a dinoflagellate, dominated in August. This indicates a shift in phytoplankton communities due to environmental factors such as phosphate deficiency and high nitrogen/phosphorus ratios. Additionally, the study notes the impact of reduced river runoff and reintroduction of scallop farming contributing to nitrogen-rich eutrophication in August. Molecular analysis revealed a disparity between microscopic observations and the prevalence of Teleaulax blooms during early summer. Elevated concentrations of TN and DOC, coupled with limited water exchange, emerged as primary factors contributing to their occurrence. Sediment analysis revealed a high diversity but low abundance of dinoflagellates in August, with a significant presence of harmful species. The study highlights the shift from diatoms to harmful dinoflagellate populations, exacerbated by eutrophication and pollution, leading to HABs. These findings provide a theoretical basis for understanding toxic algal blooms and are crucial for environmental agencies in developing strategies to protect and sustainably develop offshore environments. [ABSTRACT FROM AUTHOR]

Mesozoic-Cenozoic organic-walled dinoflagellate cyst (dinocyst) biostratigraphy is a crucial tool for relative and absolute age control in complex ancient sedimentary systems. However, stratigraphic ranges of dinocysts are found to be strongly diachronous geographically. A global compilation of state-of-the-art calibrated regional stratigraphic ranges could assist in quantifying regional differences and evaluate underlying causes. For this reason, DINOSTRAT is here initiated - an open source, iterative, community-fed database intended to house all regional chronostratigraphic calibrations of dinocyst events (https://github.com/bijlpeter83/DINOSTRAT.git). DINOSTRAT version 1.0 includes >7 8500 entries of first and last occurrences (collectively called "events") of >7 1900 dinocyst taxa, and their absolute ties to the chronostratigraphic time scale of Gradstein et al., 2012. Entries are derived from 199 publications and 189 sedimentary sections. DINOSTRAT interpolates paleolatitudes of regional dinocyst events, allowing evaluation of the paleolatitudinal variability of dinocyst event ages. DINOSTRAT allows for open accessibility and searchability, on region, age, and taxon. This paper presents a selection of the data in DINOSTRAT: (1) the (paleo)latitudinal spread and evolutionary history of modern dinocyst species; (2) the evolutionary patterns and paleolatitudinal spread of dinoflagellate cyst (sub)families; (3) a selection of key dinocyst events which are particularly synchronous. Although several dinocysts show - at the resolution of their calibration - quasi-synchronous event ages, indeed many species have remarkable diachroneity. DINOSTRAT provides the data storage approach by which the community can now start to relate diachroneity to (1) inadequate tie to chronostratigraphic time scales; (2) complications in taxonomic concepts and (3) ocean connectivity and/or the affinities of taxa to environmental conditions. [ABSTRACT FROM AUTHOR]

An integration of palynomorph and palynofacies data from the Shushan-1X well is used to infer the paleoenvironmental conditions of the Valanginian to Middle Cenomanian (Cretaceous) section of the western Shushan Basin, northern Egypt. The data obtained contribute significantly to the depositional history of the basin. The low diversity of dinoflagellate cyst assemblages, along with the dominance of land-derived spores and pollen, suggest restricted (marginal) marine environments, in contrast to their coeval representatives from the Tethyan Realm. Open marine (inner shelf) environments developed at a few horizons in the Dahab and Bahariya formations, partly contemporary with the global Aptian and Cenomanian eustatic cycles. These environments were relatively more offshore than those described in the eastern and southeastern parts of the basin. The study of total palynological organic matter (TPOM) has contributed largely to these established environmental settings. It has also allowed the recognition of redox (suboxic to anoxic) conditions and the impact of a large magnitude of terrigenous influence. [ABSTRACT FROM AUTHOR]

The paper reports palynology and palynofacies studies of lignite-bearing sediments exposed in an opencast mine succession at Surkha, Bhavnagar District, in the coastal region of Gujarat, India. The study examined the relationships between the palynoflora, sedimentary organic matter and environment at the time of deposition of lignite and associated sediments. Based on dinoflagellate cyst biostratigraphy, the sedimentary succession is dated as early Eocene (Ypresian). Palynofacies studies helped reveal the palaeoenvironmental fluctuations. The dominance of angiosperm pollen grains, freshwater algae, microthyraceous fungi and a large share of land debris in the lower part of the succession suggests a freshwater swamp environment of deposition for the basal lignite facies. Two cenozones - Matanomadiasulcites maximus and Lakiapollis ovatus - were identified in the lower lignite facies, determined from the dominance of these pollen grains in the palynological assemblages. The presence of angiosperm pollen grains and pteridophyte spores in the carbonaceous shale horizon above the lignite facies indicates a change in the depositional regime from freshwater swamp to lagoonal. This was identified as the Arecipites wodehousei cenozone due to its numerical abundance in the assemblage. Dinoflagellate cyst abundance and diversity, and microforaminiferal test linings along with well-sorted terrestrial debris in the mudstone in the upper part of the succession suggest a more open marine estuarine type of depositional environment. The Homotryblium complex along with Cordospheridium fibrospinosum, Kenleyia sp., and Thalassiphora pelagica dinoflagellate cysts are the main representatives of this zone, determined as the Homotryblium tenuispinosum cenozone. The changing depositional settings (freshwater swamp-lagoonal-estuarine) along the vertical succession indicate a marine transgression in this region. Results from palynological studies of early Palaeogene successions of the Cambay and Kutch basins correlate well with the present findings. [ABSTRACT FROM AUTHOR]

Multi-proxy analysis (spore-pollen, dinoflagellate cysts, other non-pollen palynomorphs (NPPs), radiocarbon dating and lithology) was performed on marine sediments from three new cores retrieved during the two cruise expeditions on board the Research Vessel "Akademik" in 2009 and 2011. The Varna transect comprises three cores extending from the outer shelf, continental slope and deep-water zone. The record spans the last 26000 years (all ages obtained in this study are given in calendar years BP (cal. yrs BP)). The pollen record reveals the spreading of steppe vegetation dominated by Artemisia and Chenopodiaceae, suggesting cold and dry environments during the Late Pleniglacial – Oldest Dryas (25903–15612 cal. yrs BP). Stands of Pinus and Quercus reflect warming/humidity increase during the melting pulses (19.2–14.5 cal. ka BP) and the Late Glacial interstadials Bølling and Allerød. The Younger Dryas (13257–11788 cal. yrs BP) coldest and driest environments are clearly demonstrated by the maximum relative abundance of Artemisia and Chenopodiaceae. During the Early Holocene (Preboreal and Boreal chronozones, 11788–8004 cal. yrs BP), Quercus appeared as a pioneer species and, along with other temperate deciduous arboreal taxa, formed open deciduous forests as a response to the increased temperature. The rapid expansion of these taxa indicates that they survived in Glacial refugia in the coastal mountains. During the Atlantic chronozone (8004–5483 cal. yrs BP), optimal climate conditions (high humidity and increased mean annual temperatures) stimulated the establishment of species-rich mixed temperate deciduous forests. During the Subboreal chronozone (5483–2837 cal. yrs BP), Carpinus betulus and Fagus expanded simultaneously and became more important components of mixed oak forests and probably also formed separate communities. During the Subatlantic chronozone (2837 cal. yrs BP to pre-industrial time), climate-driven changes (an increase of humidity and a cooling of the climate) appear to be the main drivers of the specific vegetation succession expressed by increased abundance of Alnus, Fraxinus excelsior and Salix along with lianas, suggesting formation of flooded riparian forests (so called 'Longoz') lining the river valleys along the Black Sea coast. The first indicators of farming and other human activities have been recorded since 7074 cal. yrs BP. The dinoflagellate cyst (dinocyst) assemblages have been analysed to assess the changes in the Black Sea environment over the last 26000 years in terms of fluctuation in paleoproduction and surface water conditions related to changes in climate, freshwater input and Mediterranean water intrusion. Two major dinocyst assemblages were distinguished: one dominated by stenohaline freshwater/brackish-water species and a successive one dominated by euryhaline marine species. The changes in the composition of the assemblages occurred at 7668 cal. yrs BP. The abrupt decrease of stenohaline freshwater/brackish-water species Pyxidinopsis psilata and Spiniferites cruciformis was followed upwards by a gradual increase in euryhaline marine species, such as Lingulodinium machaerophorum, Spiniferites belerius, S. bentorii and acritarch Cymatiosphaera globulosa. The first occurrence of euryhaline marine species took place synchronously with the onset of sapropel deposition. Modern marine conditions were established after 6417 cal yrs BP when an abundance of Mediterranean-related species, such as Operculodinium centrocarpum and Spiniferites mirabilis, along with other heterotrophic species, occurred. After the stable cold and dry environment during the Last Glacial Maximum, the phytoplankton record of core AKAD 11-17 shows that Pediastrum boryanum var. boryanum has a cyclical abundance associated with the deposition of four red-brown clay layers between 19.2 and 14.5 cal. ka BP. This event is associated with the major melting phase of European Ice drained by the Danube and Dnieper Rivers in response to climate warming observed after the end of the Last Glacial Maximum. During the Early Holocene, P. psilata, characterised by a preference to warmer temperatures, demonstrates its ecological optimum for growth concerning SST reaching maximum relative abundance of 94% between 11072 and 8638 cal. yrs BP. This maximum was interrupted by an abrupt significant short-term decrease in the relative abundance of P. psilata centred between 8500 and 8300 cal. yrs BP reflecting cold conditions similar to those of Younger Dryas. This finding, also confirmed by the rapid significant decrease of arboreal pollen, particularly of Quercus in the same studied core, is considered a regional expression of the well-known '8.2 ka cold event' which is commonly linked to a meltwater-related perturbation of the Atlantic Meridional Overturning Circulation (AMOC) and associated collapse of oceanic northward heat transport. Our fossil pollen and dinocyst data confirm that the high amplitude temperature anomaly associated with 'the 8.2 ka cold event' may have also occurred in south-eastern Europe, at lower latitudes of the western Black Sea coastal area, most probably due to atmospheric transition and/or river discharge. [ABSTRACT FROM AUTHOR]

Introduction: The production of resting cysts is a key dispersal and survival strategy of many dinoflagellate species. However, little is known about the role of suspended cysts in the benthic nepheloid layer (BNL) in the initiation and decline of planktonic populations. Methods: In September 2019, sampling of the dinoflagellate cyst community at different water depths in the water column and in the bottom sediments, and studies of spatio-temporal changes in physical properties (temperature, salinity, density and suspended sediment concentration), were carried out along a landsea transect off Figueira da Foz (NW Portugal) to investigate the dinoflagellate cyst distribution and the factors (physical and biological) affecting it. A clustering analysis was used to compare the BNL and sediment cyst records with the cyst rain recorded by a sediment trap at a fixed station. Furthermore, Lagrangian particle experiments enabled simulating cyst trajectories in the BNL 5 and 10 days before sampling and assessing cross-shore, vertical and alongshore transport within the studied region. Results: A well-developed BNL was present during the survey, which covered a change from active (14th of September) to relaxed (19th of September) upwelling conditions. Organic-walled dinoflagellate cysts were dominant in all samples, although calcareous dinoflagellate cysts consistently occurred (at low abundances). High proportions of full cysts were observed in the BNL, of which a significant portion was viable as shown by excystment experiments. Moreover, BNL cyst records collected on the 19th of September along the landsea transect were similar to the sediment trap cyst record but greatly differed from sediment cyst records. The heterotrophic small spiny brown cysts (SBC) and cysts of the autotrophic yessotoxin-producer Protoceratium reticulatum notably increased during the survey, in the BNL and in the water column above. Discussion: The comparison of the BNL, surface sediment and sediment trap cyst records supported that the main origin of cysts in the BNL was the recent production in the water column. The spatial coincidences in the distribution of cysts and vegetative cells of Protoceratium reticulatum also supported that full cysts in the water column were being produced in surface waters. New data evidenced the presence of a significant reservoir of viable cysts in the BNL that have the potential to seed new planktonic blooms. Furthermore, back-track particle modelling evidenced that alongshore advection was the main physical mechanism controlling cyst dynamics in the BNL during most part of the survey period, being particularly intense in coastal stations (<100 m depth). Consequently, the sediment cyst signal is a mixture of locally and regionally produced cysts. We provide multi-disciplinary data evidencing that cysts recently formed in the photic zone can be laterally advected within the studied region through the BNL, contributing to a better understanding of the role of the BNL in cyst dynamics and tracing the seed sources of the new blooms. [ABSTRACT FROM AUTHOR]

Sedimentary bulk organic matter and various molecular organic components exhibit strong CO 2 -dependent carbon isotope fractionation relative to dissolved inorganic carbon sources. This fractionation (εp) has been employed as a proxy for paleo- p CO 2. Yet, culture experiments indicate that CO 2 -dependent εp is highly specific at genus and even species level, potentially hampering the use of bulk organic matter and non-species-specific organic compounds. In recent years, significant progress has been made towards a CO 2 proxy using controlled growth experiments with dinoflagellate species, also showing highly species-specific εp values. These values were, however, based on motile specimens, and it remains unknown whether these relations also hold for the organic-walled resting cysts (dinocysts) produced by these dinoflagellate species in their natural environment. We here analyze dinocysts isolated from core tops from the Atlantic Ocean and Mediterranean Sea, representing several species (Spiniferites elongatus, S. (cf.) ramosus, S. mirabilis, Operculodinium centrocarpum sensu Wall and Dale (1966) (hereafter referred to as O. centrocarpum) and Impagidinium aculeatum) using laser ablation–nano-combustion–gas-chromatography–isotope ratio mass spectrometry (LA/nC/GC-IRMS). We find that the dinocysts produced in the natural environment are all appreciably more 13 C-depleted compared to the cultured motile dinoflagellate cells, implying higher overall εp values, and, moreover, exhibit large isotope variability. Where several species could be analyzed from a single location, we often record significant differences in isotopic variance and offsets in mean δ13 C values between species, highlighting the importance of single-species carbon isotope analyses. The most geographically expanded dataset, based on O. centrocarpum, shows that εp correlates significantly with various environmental parameters. Importantly, O. centrocarpum shows a CO 2 -dependent εp above ∼ 240 µ atm p CO 2. Similar to other marine autotrophs, relative insensitivity at low p CO 2 is in line with active carbon-concentrating mechanisms at low p CO 2 , although we here cannot fully exclude that we partly underestimated εp sensitivity at low p CO 2 values due to the relatively sparse sampling in that range. Finally, we use the relation between εp and p CO 2 in O. centrocarpum to propose a first p CO 2 proxy based on a single dinocyst species. [ABSTRACT FROM AUTHOR]

The relationship between wall layers in dinoflagellate cysts was investigated with transmission electron microscopy. A simple method is described in which small cysts (<100 μm) were identified, isolated, and encapsulated in colored agarose. The individual cysts, now visible to the naked eye, were easy to track throughout the multi-step protocol. The routine TEM protocol for biological material was modified and simplified for dinoflagellate cysts, and is described in detail. This method ensures that all samples can be retained, an important consideration when working with rare or unique specimens. Specimens of Hystrichosphaeropsis Deflandre 1935 were orientated for sectioning relative to the natural plane of settlement of the cyst. Serial sections demonstrated that the relationship between the endophragm and periphragm is complex and irregular. Interpretation of micrographs and some common misinterpretations of artifacts are illustrated and discussed. The protocol is presented in detail and illustrated so that an inexperienced person, with the assistance of an electron microscopy unit, could successfully carry out the procedure. The technique has been used with minor adaptations to prepare a range of biological materials and palynomorph specimens for transmission electron microscopy. [ABSTRACT FROM AUTHOR]

Rich and diverse assemblages of dinoflagellate cysts were recovered from the Gearle Siltstone in the Boologooro-1 stratigraphic well, Southern Carnarvon Basin, Western Australia. The cored interval through the Winning Group is proposed as a reference interval for the Canninginopsis denticulata, Endoceratium ludbrookiae, Dioxya armata and Xenascus asperatus dinoflagellate cyst zones of the Australian dinoflagellate cyst zonal scheme. The ranges of sixty-three dinoflagellate cyst species are documented in detail over this interval. Apart from the bioevents that define the widely-used dinoflagellate cyst subzones, the highest occurrences of Endoceratium turneri, Craspedodinium indistinctum and Litosphaeridium arundum, and the lowest occurrences of Nematosphaeropsis densiradiata,Canninginopsis denticulata, Leberidocysta chlamydata, Aptea? sp. cf. Aptea polymorpha, Litosphaeridium siphoniphorum, Balcattia cirribarbata and Stephodinium australicum are recognized as potential biostratigraphic datums in the Southern Carnarvon Basin. Species diversity increased in the highest Canninginopsis denticulata Zone at approximately the horizon where Diconodinium spp. become dominant. Foraminiferal data indicate the interval from 361.15 m to 312.12 m is marginally inner neritic and corresponds with an interval of abundant Diconodinium spp., and fewer Spiniferites spp. Diversity increased in the Xenascus asperatus Zone with an increase in Spiniferites spp., and a shift to middle neritic paleobathymetry. The age of the top of the Xenascus asperatus Zone is constrained by calcareous nannofossils and dinoflagellate cyst correlations to the latest Albian, or possibly the early Cenomanian. The age of the base of the Canninginopsis denticulata Zone is constrained by dinoflagellate cyst and foraminiferal data to the early Albian, above the earliest Albian. One new species, Chlamydophorella haigii, is erected and aspects of several other dinoflagellate cyst taxa are reviewed. [ABSTRACT FROM AUTHOR]

A Middle Campanian (Late Cretaceous) eustatic sea-level rise recorded in the Belgorod succession (Russia; eastern North European Basin) was analyzed. The succession, dated for the Gavelinella annae and Globorotalites emdyensis foraminiferal zones (corresponding to the 'Inoceramus' azerbaydjanensis-'Inoceramus' vorhelmensis inoceramid Zone), records the deposition of pure chalk, with only trace terrigenous material. Its distal offshore position limited terrestrial nutrient delivery, driving oligotrophic conditions that influenced benthic foraminifera and organic-walled phytoplankton communities. Eustatic changes are recorded by planktonic foraminifera and additionally reflected in phytoclast abundance, organic-walled dinoflagellate cysts (dinocysts), calcareous dinoflagellate cysts (c-dinocysts), and d13C and d18O fluctuations. Most indices were primarily driven by variable terrestrial organic matter and freshwater influxes, acting as a function of sea depth and land topography. [ABSTRACT FROM AUTHOR]

Analysis of compositional changes in fossil organic-walled dinoflagellate cyst (dinocysts) assemblages is a widely used tool for the quantitative reconstruction of past environmental parameters. This approach assumes that the assemblage composition is significantly related to the reconstructed environmental parameter, which requires an independent correlation between the assemblage and the variable, meaning that the variable explains a dimension of the assemblage variance that is not also explained by other parameters. Theoretically, dinocyst assemblages can be used to reconstruct multiple environmental variables. However, there is evidence that primary and subordinate drivers for assemblage compositions regionally differ, and it remains unclear whether a significant relationship to specific parameters in the present ocean always implies that this relationship is significant in fossil assemblages, questioning if past changes in these multiple parameters can be reconstructed simultaneously from fossil assemblages. Here, we analysed a local subset of the Northern Hemisphere dinocyst calibration dataset (n=1968), including samples from the Baffin Bay area (n=421), and evaluated the benefits of a local versus a more regional or global calibration for the environmental reconstruction of Baffin Bay oceanography during the Holocene. We determined the dimensionality of the dinocyst ecological response and identified environmental drivers in the Baffin Bay area for the modern dataset. We analysed four existing Holocene records along a north–south transect in the area and evaluated the statistical significance of downcore reconstructions by applying the local and global datasets with different techniques: the modern analogue technique (MAT), the weighted average partial least square (WA-PLS) and maximum likelihood (ML). We evaluated reconstructions tested as significant in light of the existing state of knowledge about West Greenland's Holocene palaeoceanography. Our analyses imply that present-day and Holocene dinocyst assemblages in the Baffin Bay area are primarily driven by salinity changes; other parameters were less important in driving assemblage compositions, and their contribution differed among the studied records. We show that the objectively occurring and temporally coherent shifts in dinocyst assemblages in the Holocene of Baffin Bay can be robustly interpreted only by transfer functions that are locally calibrated. Transfer functions based on the broad Northern Hemisphere calibration yielded many insignificant environmental reconstructions. At the same time, we show that even in the local calibration, not all parameters that appear to significantly affect dinocyst assemblages in the calibration dataset can be meaningfully reconstructed in the fossil record. A thorough evaluation of the calibration dataset and the significance of downcore applications is necessary to reveal the region-specific information contained in dinocyst assemblage composition. [ABSTRACT FROM AUTHOR]

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Eocene transient global warming events (hyperthermals) can provide insight into a future warmer world. While much research has focused on the Paleocene–Eocene Thermal Maximum (PETM), hyperthermals of a smaller magnitude can be used to characterize climatic responses over different magnitudes of forcing. This study identifies two events, namely the Eocene Thermal Maximum 2 (ETM2 and H2), in shallow marine sediments of the Eocene-aged Salisbury Embayment of Maryland, based on magnetostratigraphy, calcareous nannofossil, and dinocyst biostratigraphy, as well as the recognition of negative stable carbon isotope excursions (CIEs) in biogenic calcite. We assess local environmental change in the Salisbury Embayment, utilizing clay mineralogy, marine palynology, δ18 O of biogenic calcite, and biomarker paleothermometry (TEX 86). Paleotemperature proxies show broad agreement between surface water and bottom water temperature changes. However, the timing of the warming does not correspond to the CIE of the ETM2 as expected from other records, and the highest values are observed during H2, suggesting factors in addition to p CO 2 forcing have influenced temperature changes in the region. The ETM2 interval exhibits a shift in clay mineralogy from smectite-dominated facies to illite-rich facies, suggesting hydroclimatic changes but with a rather dampened weathering response relative to that of the PETM in the same region. Organic walled dinoflagellate cyst assemblages show large fluctuations throughout the studied section, none of which seem systematically related to CIE warming. These observations are contrary to the typical tight correspondence between climate change and assemblages across the PETM, regionally and globally, and ETM2 in the Arctic Ocean. The data do indicate very warm and (seasonally) stratified conditions, likely salinity-driven, across H2. The absence of evidence for strong perturbations in local hydrology and nutrient supply during ETM2 and H2, compared to the PETM, is consistent with the less extreme forcing and the warmer pre-event baseline, as well as the non-linear response in hydroclimates to greenhouse forcing. [ABSTRACT FROM AUTHOR]

Information on Jurassic palynomorphs from the Greater Caucasus is potentially of great importance, but its availability to the international research community is severely limited. New palynological data for Toarcian deposits of the Western Caucasus are recorded in the present paper. Particularly, dinoflagellate cysts are described for the first time from the Bagovskaja Formation; palynomorphs are found in sandstone levels within this unit. The most representative assemblage includes pollen (with predominant bisaccate pollen), spores (Cyathidites being commonest), and dinoflagellate cysts amongst which the predominant taxon is Nannoceratopsis spiculata. The dinocyst assemblage implies a late Toarcian age for the upper part of the Bagovskaja Formation. On the basis of these new palynostratigraphical results, the range of the formation is extended; previously, only the lower part had been dated on ammonite evidence. [ABSTRACT FROM AUTHOR]

Both marine dinoflagellate cysts and terrestrially derived pollen and spores are abundant in coastal sediments close to river mouths, making sediment records from such settings ideal to simultaneously study land–ocean climate interactions, marine productivity patterns and freshwater input over time. However, few studies consider the combined calibration of these palynological proxies in modern coastal sediments offshore from rivers, which is needed to strengthen the interpretation of paleoreconstructions. Here, we analyze the palynological content of marine surface sediments along land–sea transects off the Mississippi and Atchafalaya river mouths in the northern Gulf of Mexico (GoM) and test three palynological indices which are often employed in the paleo-domain: (i) the abundance of cysts of heterotrophic and autotrophic dinoflagellates (dinocysts) as a tracer for primary productivity (H/A ratio) and (ii) the ratio between non-bisaccate pollen and bisaccates (P/B) as well as (iii) the ratio between pollen (excluding bisaccates) and dinocysts (P/D), which are both tracers for river input and distance to the coast. Our results show that dinoflagellate cysts are most abundant on the shelf, where heterotrophic dinocyst species dominate coastal assemblages in reach of the river plume, while autotrophic taxa are more present in the oligotrophic open ocean. This is clearly reflected in decreasing H/A values further offshore. Individual dinocyst taxa also seem to inhabit specific niches along an onshore–offshore transect, linked to nutrient availability and proximity to the turbid river plume. The highest pollen concentrations are found close to the Mississippi river mouth and mostly represent a mixture of local coastal and upstream vegetation, whereas bisaccate pollen was most abundant further offshore of the Mississippi river. Multivariate redundancy analysis (RDA) performed on both pollen and dinocyst assemblages, a set of environmental parameters, and the three palynological ratios showed that net primary productivity was the most important variable influencing the dinocyst assemblages, likely as the result of nutrient input. Additionally, the RDA confirmed that the H/A ratio indeed seems to track primary productivity, while the P/B ratio results in a robust indicator for distance to the coast, and the P/D ratio better reflects river input. Together, our data confirm and further specify the suitability of these three palynological ratios in river-dominated coastal margins as proxies for (past) marine productivity and distance to the coast and river. [ABSTRACT FROM AUTHOR]

Sea level oscillation during the Quaternary played a major role in the geomorphology and vegetation dynamics of coastal areas in southern Brazil, encompassing ecosystems that often have a unique biodiversity. Understanding the natural evolution of these areas is essential for decision making regarding land use regulations towards sustainable development, as well as to preserve the uniqueness of the coastal ecosystems. The southern Brazil coastal plain is formed by marine, transitional and continental Quaternary deposits controlled by past variations of the sea level. These variations shaped the coastal landscape and influenced the development of different Atlantic rainforest formations, such as mangroves and restingas. In particular, the restinga formation corresponds to a specific ecosystem that covers sandy soils of marine and fluvial–marine origin formed during the Quaternary on the Brazilian coastal plain. In this contribution, we present high-resolution palynological and stable isotope data from a Holocene core retrieved from the coastal plain of Santa Catarina Island (southern Brazil). We were able to identify four different environmental zones for the last 6520 yr BP. The first zone (6520–2920 cal yr BP) is characterized by a lagoon with large marine-water influence. Notably, the observed dinoflagellate cyst association suggests that marine waters entering the region had their origin in the relatively warm and saline Brazil Current waters. During the second zone (2920–1520 cal yr BP), marine-water contribution to the lagoon decreased until it became disconnected from the sea. The third zone (1520–550 cal yr BP) was marked by the decrease of the water level until it dried out and led to the colonization of herbaceous vegetation over the palaeo-lagoon. The last zone (550 cal yr BP–recent) is characterized by the consolidation of the coastal-plain Atlantic rainforest (restinga vegetation). Our results form an example of the strong sensitivity of southern Brazilian ecosystem change caused by relative sea level variations. As such, this study might contribute to the debate about the potential effects of current climate change induced by global sea level variations. [ABSTRACT FROM AUTHOR]

The Lower Cretaceous syn‐rift deposits of the Douala Basin (Mundeck Formation), located in the equatorial West African margin were investigated in order to determine the palaeoenvironment and organic matter source, redox conditions, palaeoclimate, and tectonic settings, based on facies, organic and inorganic geochemical analyses. The sediments consist of pebble, coarse, medium‐ to fine‐grained sandstone, siltstone, and grey to black fossiliferous shales. The shales are characterized by an average total organic carbon (TOC) of 1.02%, fair to poor source generative potential with present‐day hydrogen index values, which range from 31 to 350 mg HC/g TOC suggesting that the shale contains Type III kerogens with mainly gas generative potential. The organic particles are dominated by phytoclasts (40% on average) and non‐fluorescent amorphous organic matter (34% on average). The palynomorphs represent about 26% on average with a large amount of pollen grain and a minor amount of dinoflagellate cysts and microforaminifera test linings. The inferred depositional environment of the studied sediments is an alluvial fan to fluvio‐lacustrine with shallow marine incursion. This depositional environment received the contribution of aquatic algae and microorganisms with a large amount of terrestrial organic matter, evidenced by the presence of some dinoflagellate cysts and microforaminifera test linings, and relatively higher amounts of SiO2, Al2O3, and phytoclasts. The presence of trace elements such as Ba, Sr, V, Ni, Co and Cr in the analysed samples and their ratio, suggest suboxic to anoxic conditions of deposition with low salinity. The warm to cold and dry climatic conditions prevailed during the deposition of the Mundeck deposits and sediments from active continental margin setting during the lower Cretaceous periods in the Douala Basin as confirmed by inorganic geochemical data. This study sheds light on the early stage of the evolution of the Douala Basin which could be integrated into the context of a mid‐Jurassic to lower Cretaceous regional evolution of the opening of a passive margin. This evolution is characterized by an alluvial fan, fluviatile, lacustrine, lagoon and marine depositional system. This depositional system is recognized as part of the petroleum system recognized within the syn‐rift deposits in the others basins along the West African margin, where giant hydrocarbons have been discovered. [ABSTRACT FROM AUTHOR]

The first records of dinocysts and foraminifers in the Middle Jurassic deposits of the Russian Far East and their taxonomic affiliation are reported. The use of foraminiferal and ostracod assemblages as a tool for biostratigraphic subdivision and correlation of the Middle Jurassic sections of this region is very difficult due to the poor preservation and limited occurrence of these microfossils. Findings of the dinocysts Endoscrinium galeritum,Tubotuberella cf. apatela,Wanaea fimbriata, and Meiourogonyaulax cf. caytonensis raise the question of correcting the stratigraphic range of the lithological formations recognized in the Middle Jurassic. [ABSTRACT FROM AUTHOR]

The Middle Jurassic in the north Western Desert, Egypt, was a time of complex tectonics and increased environmental perturbations attributed to the predominant sedimentation of organic carbon-rich fine siliciclastic and carbonate deposits of the Khatatba Formation. Although some studies have addressed the hydrocarbon potential and source rock characteristics of the Khatatba Formation, a regional-scale investigation of the prevalent paleoenvironmental conditions and organic matter characteristics is still necessary. In this study, the Khatatba Formation is investigated for detailed palynofacies analysis and palynomorph composition to assess organic matter kerogen types and reconstruct the depositional paleoenvironmental patterns on a regional scale. For this purpose, 116 drill cuttings were collected from five wells in the Matruh, Shushan, and Dahab-Mireir Basins. Moderately diverse assemblages of spores, pollen, and dinoflagellate cysts are reported. Age-diagnostic dinoflagellate cysts, including Adnatosphaeridium caulleryi, Dichadogonyaulax sellwoodii, Korystocysta gochtii, Wanaea acollaris, and Pareodinia ceratophora, along with occasional records of Systematophora areolate and Systematophora penicillate, defined a Bajocian–Callovian age. Based on particulate organic matter (POM) composition, four palynofacies assemblages (PFAs) are identified. PFA-1 is the most common within the Khatatba Formation in the five studied wells. It contains high proportions of phytoclast fragments versus low contents of amorphous organic matter (AOM) and palynomorphs and is defined by a gas-prone kerogen Type III. PFA-2 is comprised of moderate abundances of AOM and phytoclast characteristics of oil-prone kerogen Type II. PFA-3 is dominated by phytoclasts and moderate to low proportions of AOM and palynomorphs of kerogen Type III, whereas PFA-4 consists of AOM and palynomorphs defining kerogen Type II. PFA-1 indicates predominant deposition in proximal active fluvio-deltaic sources to marginal marine conditions with enhanced contributions of terrestrial/riverine influx. PFA-2 and PFA-3 reveal deposition under an enhanced dysoxic to anoxic proximal inner neritic shelf due to the abundant occurrences of spores and coastal to shallow marine dinoflagellate cysts. PFA-4 suggests deposition under enhanced suboxic to anoxic distal inner neritic conditions because of enhanced AOM and abundant proximate and some chorate dinoflagellate cysts. Thus, the Middle Jurassic experienced a predominantly marginal to shallow water column in this part of the southern margin of the Tethyan Ocean where the Matruh, Shushan, and Dahab-Mireir Basins were located. [ABSTRACT FROM AUTHOR]

Changes in terrestrial vegetation during the mid-Cretaceous and their link to climate and environmental change are poorly understood. In this study, we use plant macrofossils and analysis of fossil pollen and spores from the Western Desert, Egypt, to assess temporal changes in plant communities during the Cenomanian. The investigated strata have relatively diverse sporomorph assemblages, which reflect the nature of parent vegetation. Specifically, the palynofloras represent ferns, conifers, monosulcate pollen producers, Gnetales, and a diverse group of angiosperms. Comparisons of both, dispersed palynoflora and plant macrofossils reveal different characteristics of the palaeoflora owing to a plethora of taphonomical and ecological biases including the depositional environment, production levels, and discrepancies between different plant organs. A combination of detailed records of sporomorphs, leaves, and charcoal from the studied successions provide new understandings of the palaeoclimate and palaeogeography during the Cenomanian and Albian-Cenomanian transition in Egypt. The mixed composition of the palynofloral assemblages reflects the presence of different depositional situations with a weak marine influence, as evidenced by a minor dinoflagellate cysts component. The local vegetation comprised various categories including herbaceous groups including ferns and eudicots, fluvial, open environments, and xeric arboreal communities dominated by Cheirolepidiaceae and perhaps including drought- and/or salt-tolerating ferns (Anemiaceae) and other gymnosperms (Araucariaceae, Ginkgoales, Cycadales, and Gnetales) as well as angiosperms. The presence of riparian and freshwater wetland communities favouring aquatic and/or hygrophilous ferns (of Salviniaceae and Marsileaceae), is noted. The wide variation of depositional settings derived from the palynological data may be attributed to a prevalent occurrence of producers in local vegetation during the early Cenomanian of Egypt. For the purpose of this work on the studied Bahariya Formation and its equivalent rock units, where iconic dinosaurs and other fossil fauna roamed, we attempt to improve the understanding of Egypt's Cenomanian climate, which is reconstructed as generally warm and humid punctuated by phases of considerably drier conditions of varying duration. [ABSTRACT FROM AUTHOR]

Copyright of BSGF: Earth Sciences Bulletin is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Palynological and sedimentological analyses were performed on the sediment core HH16‐1205‐GC retrieved from the central Isfjorden, West Spitsbergen. The sequence, which spans the last 7000 years, revealed an overall cooling trend with an important climate shift between 4.4 and 3.8 cal. ka BP, in addition to millennial‐scale oscillations. Sea‐surface reconstruction from dinocyst assemblages indicates a decrease in summer sea‐surface temperature, from 2.5 to 1.5 °C, and primary productivity, from 750 to 650 gC m−2 a−1 over the last 7000 years. From around 6.8 to 5.8 cal. ka BP, the sedimentological and palynological data suggest a predominant sediment supply from the inner part of the fjord, ice rafting, dense sea ice cover, strongly stratified water masses and high primary productivity. The interval from 4.4 to 3.8 cal. ka BP is marked by a layer of coarser material and a significant decrease in the grain‐size mode. Our geochemical data show large‐amplitude fluctuations after 2.0 cal. ka BP, while an increase in the dinocysts Impagidinium pallidum and Spiniferites elongatus from 2.0 to 1.2 cal. ka BP suggests enhanced Atlantic Water inflow. The dinocyst‐based reconstructions also reveal large‐amplitude millennial fluctuations in sea ice cover, summer sea‐surface temperature and salinity. Wavelet analysis and cross‐wavelet analysis on K/Ti ratio coupled with sea‐ice estimates confirm a strong signal with a periodicity of 1200–1500 years. [ABSTRACT FROM AUTHOR]

Dinoflagellate cyst assemblages present a valuable proxy to infer paleoceanographic conditions, yet factors influencing geographic distributions of species remain largely unknown, especially in the Southern Ocean. Strong lateral transport, sea-ice dynamics, and a sparse and uneven geographic distribution of surface sediment samples have limited the use of dinocyst assemblages as a quantitative proxy for paleo-environmental conditions such as sea surface temperature (SST), nutrient concentrations, salinity, and sea ice (presence). In this study we present a new set of surface sediment samples (n=66) from around Antarctica, doubling the number of Antarctic-proximal samples to 100 (dataset wsi_100) and increasing the total number of Southern Hemisphere samples to 655 (dataset sh_655). Additionally, we use modelled ocean conditions and apply Lagrangian techniques to all Southern Hemisphere sample stations to quantify and evaluate the influence of lateral transport on the sinking trajectory of microplankton and, with that, to the inferred ocean conditions. k -means cluster analysis on the wsi_100 dataset demonstrates the strong affinity of Selenopemphix antarctica with sea-ice presence and of Islandinium spp. with low-salinity conditions. For the entire Southern Hemisphere, the k -means cluster analysis identifies nine clusters with a characteristic assemblage. In most clusters a single dinocyst species dominates the assemblage. These clusters correspond to well-defined oceanic conditions in specific Southern Ocean zones or along the ocean fronts. We find that, when lateral transport is predominantly zonal, the environmental parameters inferred from the sea floor assemblages mostly correspond to those of the overlying ocean surface. In this case, the transport factor can thus be neglected and will not represent a bias in the reconstructions. Yet, for some individual sites, e.g. deep-water sites or sites under strong-current regimes, lateral transport can play a large role. The results of our study further constrain environmental conditions represented by dinocyst assemblages and the location of Southern Ocean frontal systems. [ABSTRACT FROM AUTHOR]

The Upper Cretaceous succession (Coniacian to lowermost Maastrichtian, with focus on the Campanian) at Petrich, Central Srednogorie Zone in Bulgaria, is described and calibrated stratigraphically based on nannofossils, dinoflagellate cysts and inoceramids. The following standard nannofossil zones and subzones are identified: UC10–UC11ab (middle to upper Coniacian), UC11c–UC12–UC13 (uppermost Coniacian to Santonian), UC14a (lowermost Campanian), UC14bTP–UC15cTP (lower Campanian to ‘middle’ Campanian), UC15dTP– UC15eTP (upper Campanian), UC16aTP (of Thibault et al. 2016; upper part of the upper Campanian), and UC16b (Campanian–Maastrichtian boundary). The base of the Campanian is defined by the FO of Broinsonia parca parca (Stradner) Bukry, 1969 and Calculites obscurus (Deflandre) Prins and Sissingh in Sissingh, 1977 (a morphotype with a wide central longitudinal suture). The Areoligera coronata dinoflagellate cyst Zone (upper lower Campanian to upper upper Campanian) is identified, corresponding to the UC14bTP–UC16aTP nannofossil subzones. The inoceramid assemblage indicates the ‘Inoceramus’ azerbaydjanensis–‘Inoceramus’ vorhelmensis Zone, correlated within the interval of nannofossil subzones UC15dTP–UC15eTP. The composition of the dinoflagellate cyst assemblages and palynofacies pattern suggest normal marine, oxic conditions and low nutrient availability within a distal shelf to open marine depositional environment during the Campanian. [ABSTRACT FROM AUTHOR]

Similar to the seeds of higher plants, resting cysts, a non-motile, benthic, and dormant stage in the life history of many dinoflagellate species, play vital roles via germination in the seasonal dynamics and particularly the initiation of harmful algal blooms (HABs) of dinoflagellates. It is thus crucial for resting cysts to balance between the energetic catabolism for viability maintenance and the energy preservation for germination during their dormancy. Despite this importance, studies on how resting cysts of dinoflagellates accomplish energetic metabolism in marine sediment have been virtually absent. In this study, using the cosmopolitan HABs-causing species Scrippsiella acuminata as a representative, we measured the transcriptional activity of the most efficient pathway of the energy catabolism tricarboxylic acid (TCA) cycle, cell viability (via neutral red staining), and the cellular ATP content of resting cysts under a set of mock conditions in marine sediments (e.g., 4 °C, darkness, and anoxia) for a maximum period of one year. Based on the correlation analyses among the expression levels of genes, cyst viability, and ATP content, we revealed that the TCA cycle was still a crucial pathway of energetic catabolism for resting cysts under aerobic conditions, and its expression was elevated at higher temperatures, light irradiation, and the early stage of dormancy. Under anaerobic conditions, however, the TCA cycle pathway ceased expression in resting cysts, as also supported by ATP measurements. Our results have laid a cornerstone for the comprehensive revelation of the energetic metabolism and biochemical processes of dormancy of resting cysts in marine sediments. [ABSTRACT FROM AUTHOR]

This quantitative dinoflagellate cyst study reveals an enormous difference in survival rates in oxygenated versus anoxic sediments. Replicate samples of concentrated natural dinoflagellate cysts with the same initial species composition (1.4 × 104 resting cysts·cm−3 sediment, 61% filled with live-appearing contents) were placed in bags of 20 µm plankton screen. Replicate bags containing 10.0 cm−3 concentrated cyst samples were placed on the seafloor in different environments in Long Island Sound, USA (anoxic and oxygenated), as well as refrigerated in test tubes in the laboratory. Three sets of 15 bags were placed in each environment. Once every year for four consecutive years, three bags were recovered from each set, and the contents were analyzed by cyst counting and germination experiments. An enormous difference in preservation potential between samples in oxygenated versus anoxic environments was revealed. The number of dinoflagellate cysts decreased abruptly within the first year in the oxygen-rich environment; living cysts became very rare (only 5% remained) and also empty walls of cysts disappeared (20% of total cysts remained). In anoxic sediment samples, living cysts also decreased significantly with time, but less quickly. After 1 year, 35% of the living cysts in the anoxic environment and 70% of the living cysts refrigerated in test tubes remained intact. After 4 years, 21% of the cysts with contents in the anoxic environment remained, and 31% in test tubes. The empty cyst walls remained intact for a longer time under anoxic conditions, especially of species known to fossilize well. Germination experiments showed that cysts with live-appearing contents were likely alive, because species with identifiable live-appearing cysts were also identified as vegetative cells in corresponding slurry cultures. The cyst assemblage was dominated by Protoperidinaceae, Dipolopsalidaceae, and Gonyaulacaceae. Of special interest is the ichthyotoxic Margalefodinium polykrikoides, the bloom-forming Peridinium quinquecorne, which has an undescribed resting cyst, and a previously undescribed Krypoperidinium species. The results show greater preservation of dinoflagellate cysts in "dead-zone sea bottoms" and may also provide an answer to the question of the absence of cyst beds in an area despite observed sedimentation of dense blooms. [ABSTRACT FROM AUTHOR]

Sediments are periodically dredged from the major ports in the Gulf of Gabes (GG) during maintenance operations. These sediments are dumped near the coats of Sfax and Gabes cities. In the present study, 6 trace metals (Cd, Cu, Cr, Ni, Pb, and Zn) concentrations were assessed in both sediments and column water taken from the different basins of Sfax port. This study is the first to focus on the microbial and microalgae contaminations of Sfax port sediments. The spatial distributions of trace metals in dredged sediments from the different basins of Sfax port show that the maximum concentrations of Cd (13.75 µg/g), Cu (892.5 µg/g), and Zn (1447 µg/g) exceeded the Geode standard thresholds. The same elements, also detected in the water column, exceeded the toxicity thresholds for phytoplankton, shellfish, and algae (Cd 0.095 µg/l, Cu 4.52 µg/l, and Zn 37 µg/l). The presence of coliforms, indicators of sewage pollution, as pathogenic germs (Pseudomonas), was shown through microbiological examinations of the sediments and water column. The microalgae enumeration showed the abundance of dinoflagellate cysts (stressed form) which attests to the presence of severe conditions in Sfax port. Different toxic species were identified as Prorocentrum lima and Alexandrium minutum. The same trace metal sources and abundance in Sfax port and GG sediments suggest the hypothesis of their transfer from their disposal sites in coastal areas to deeper depths in the GG and until Boughrara lagoon (BL). As trace metals, microalgae species were also transferred by hydrodynamic currents inside the GG where they found suitable conditions to their proliferation causing the seawater coloration phenomenon, eutrophication, and degradation of the aquatic system. [ABSTRACT FROM AUTHOR]

Palynostratigraphic and palynofacies analysis have been performed on hydrocarbon seep carbonate, carbonate nodule and mudstone samples from the Early Cretaceous Kuhnpasset Beds in the Kuhnpasset area of Wollaston Forland, Northeast Greenland. Three informal palynostratigraphic zones have been defined based on dinoflagellate cyst occurrences. The zones range from ?early Barremian to early Aptian in age, and correlate with previously defined dinoflagellate cyst zones in Northeast Greenland. These zones indicate hydrocarbon seepage in Kuhnpasset spanned the ?early-late Barremian age range, but did not continue into the Aptian, and thus seep activity continued for as much as three million years. Palynofacies analysis is used to interpret the depositional environment of the Kuhnpasset Beds and indicate that the hydrocarbon seeps and associated mudstones from this sedimentary sequence were deposited in a proximal shelf setting. [ABSTRACT FROM AUTHOR]

Statistical climate reconstruction techniques are fundamental tools to study past climate variability from fossil proxy data. In particular, the methods based on probability density functions (or PDFs) can be used in various environments and with different climate proxies because they rely on elementary calibration data (i.e. modern geolocalised presence data). However, the difficulty of accessing and curating these calibration data and the complexity of interpreting probabilistic results have often limited their use in palaeoclimatological studies. Here, I introduce a new R package (crestr) to apply the PDF-based method CREST (Climate REconstruction SofTware) on diverse palaeoecological datasets and address these problems. crestr includes a globally curated calibration dataset for six common climate proxies (i.e. plants, beetles, chironomids, rodents, foraminifera, and dinoflagellate cysts) associated with an extensive range of climate variables (20 terrestrial and 19 marine variables) that enables its use in most terrestrial and marine environments. Private data collections can also be used instead of, or in combination with, the provided calibration dataset. The package includes a suite of graphical diagnostic tools to represent the data at each step of the reconstruction process and provide insights into the effect of the different modelling assumptions and external factors that underlie a reconstruction. With this R package, the CREST method can now be used in a scriptable environment and thus be more easily integrated with existing workflows. It is hoped that crestr will be used to produce the much-needed quantified climate reconstructions from the many regions where they are currently lacking, despite the availability of suitable fossil records. To support this development, the use of the package is illustrated with a step-by-step replication of a 790 000-year-long mean annual temperature reconstruction based on a pollen record from southeastern Africa. [ABSTRACT FROM AUTHOR]

Cores from site HLY0501-05 on the Alaskan margin in the eastern Chukchi Sea were analyzed for their geochemical (organic carbon, δ13Corg, Corg/N, and CaCO3) and palynological (dinocyst, pollen, and spores) content to document oceanographic changes during the Holocene. The chronology of the cores was established from 210Pb dating of near-surface sediments and 14C dating of bivalve shells. The sediments span the last 9000 years, possibly more, but with a gap between the base of the trigger core and top of the piston core. Sedimentation rates are very high (~156 cm/ka), allowing analyses with a decadal to centennial resolution. The data suggest a shift from a dominantly terrigenous to marine input from the early to late Holocene. Dinocyst assemblages are characterized by relatively high concentrations (600–7200 cysts/cm3) and high species diversity, allowing the use of the modern analogue technique for the reconstruction of sea-ice cover, summer temperature, and salinity. Results indicate a decrease in sea-ice cover and a corresponding, albeit much smaller, increase in summer sea-surface temperature over the past 9000 years. Superimposed on these long-term trends are millennial-scale fluctuations characterized by periods of low sea-ice and high sea-surface temperature and salinity that appear quasi-cyclic with a frequency of about one every 2500–3000 years. The results of this study clearly show that sea-ice cover in the western Arctic Ocean has varied throughout the Holocene. More importantly, there have been times when sea-ice cover was less extensive than at the end of the 20th century. Des carottes provenant du site HLY0501-05 sur la marge de l’Alaska dans la partie est de la mer des Tchouktches ont été analysées pour leur contenu géochimique (carbone organique, δ13Corg, Corg/N, CaCO3) et palynologique (dinokystes, pollen, spores) afin de documenter les changements océanographiques survenus au cours de l’Holocène. La chronologie des carottes a été déterminée à partir d’une datation 210Pb des sédiments près de la surface et d’une datation 14C de coquilles de bivalves. Les sédiments couvrent les derniers 9000 ans, possiblement plus, mais avec une lacune entre la base de la carotte prélevée par carottier à clapet et le haut de la carotte prélevée par carottier à piston. Les taux de sédimentation sont très élevés (~156 cm/ka), permettant des analyses avec une résolution variant de décennale à centennale. Les données suggèrent un approvisionnement qui a passé de surtout terrigène à marin entre l’Holocène précoce et tardif. Les assemblages de sont caractérisés par des concentrations relativement hautes de dinokystes (600–7200 par cm3) et une diversité élevée permettant l’utilisation d’une technique analogique moderne pour la reconstruction de la couverture des glaces de mer, des températures estivales et de la salinité. Les résultats indiquent une diminution de la couverture des glaces de mer et une augmentation, quoique bien moindre, de la température estivale de la surface de la mer au cours des 9000 dernières années. À ces tendances à long terme se superposent des fluctuations à l’échelle millénaire, caractérisées par des périodes de mince glace de mer et de températures élevées de la surface de la mer et une forte salinité qui semblent quasi cycliques, avec une période de récurrence d’une fois tous les 2500 à 3000 ans. Les résultats de cette étude démontrent clairement que la couverture des glaces de mer dans l’océan Arctique occidental a varié tout au long de l’Holocène. De manière encore plus significative, il y a eu des périodes où la couverture des glaces de mer était moins étendue qu’à la fin du 20e siècle. [ABSTRACT FROM AUTHOR]

Herein are presented the results of detailed bio- (calcareous dinocysts, calpionellids, foraminifers, saccocomids) and chemostratigraphic (δ13C) studies combined with high-resolution microfacies, rock magnetic and gamma-ray spectrometry (GRS) investigations performed on the upper Kimmeridgian-upper Valanginian carbonates of the Giewont succession (Tatricum, Giewont and Mały Giewont sections, Western Tatra Mountains, Poland). The interval studied covers the contact between the Raptawicka Turnia Limestone (RTL) Fm. and the Wysoka Turnia Limestone (WTL) Fm. Their sedimentary sequence is composed of micrites, pseudonodular limestones, cyanoid packstones, lithoclastic packstone and encrinites. A precise correlation with the previously published Mały Giewont section is ensured by biostratigraphy, rock magnetic and GRS logs. The methodology adopted has enabled the recognition of two stratigraphic discontinuities, approximated here as corresponding to the latest Tithonian-early (late?) Berriasian and the early Valanginian. The hiatuses are evidenced by biostratigraphic data and the microfacies succession as well as by perturbations in isotopic compositions and rock magnetic logs; they are thought to result from a conjunction of tectonic activity and eustatic changes. A modified lithostratigraphic scheme for the Giewont and the Osobita High-Tatric successions is proposed. The top of the RTL Fm. falls in the upper Tithonian, where cyanoid packstones disappear. At the base of the WTL Fm. a new Giewont Member is defined as consisting of a basal lithoclastic packstone and following encrinites. [ABSTRACT FROM AUTHOR]

Discussions on the age and the depositional environments of the Veldhoven Formation and its members are persistent in Belgium and the Netherlands. Uncertainties on stratigraphy and the constructive process of sediment accumulation continue today as a result of lack of data on this succession within the Roer Valley Rift System. The present study provides new information on the bio- and lithostratigraphy and facies from two boreholes based on dinoflagellate cyst taxa. The results were correlated by gamma-ray logs towards other key boreholes in the region and show a good consistency for stratigraphy and depositional environments for the members of the Veldhoven Formation. After marginal to restricted marine conditions in the latest Rupelian (early Oligocene), the start of deposition of the Veldhoven Formation marked the transition towards a higher sea level, expressed by increased glauconite contents and gamma-ray values. The Voort Member in the lower part of the Veldhoven Formation has an early to late Chattian (Late Oligocene) age and comprises predominantly shallow marine (fluctuating restricted to open marine) conditions. The lithology in the lower part of this unit is often very clayey but is coarsening upward into sands. The superjacent Wintelre Member has a latest Chattian to early Aquitanian (early Miocene) age. This member is distinct by its clayey nature which is expressed by relatively high gamma-ray values. Earlier studies suggest a deeper marine facies for the Wintelre Member compared to the Someren and Voort members. However, the dinoflagellate cyst assemblages in this unit are mostly dominated by a single genus indicating a restricted marine setting, including salinities that deviate from normal marine conditions, most probably due to minor ventilation by narrow or lack of connection to the Atlantic Ocean. A glacio-eustatic sea-level fall around the Oligocene/Miocene boundary limited the sea coverage to the strongest subsiding areas, where deposition of the Wintelre Member is recorded, while non-deposition or erosion occurred in the surrounding highs, hence creating an isolated (sub)basin. The superjacent Someren Member was deposited during the late Aquitanian to middle Burdigalian and consists of shallow to open marine clayey fine sands. Increasing clay contents indicate a gradual development towards a higher sea level, which coincide with upward increasing gamma-ray values. The biostratigraphic results of this study suggest that no major hiatuses are present in the differentially subsiding blocks of the Roer Valley Rift System during the late Oligocene to early Miocene. [ABSTRACT FROM AUTHOR]

Sea surface temperature (SST) reconstructions based on isoprenoid glycerol dialkyl glycerol tetraether (isoGDGT) distributions from the Eocene southwest (SW) Pacific Ocean are unequivocally warmer than can be reconciled with state-of-the-art fully coupled climate models. However, the SST signal preserved in sedimentary archives can be affected by contributions of additional isoGDGT sources. Methods now exist to identify and possibly correct for overprinting effects on the isoGDGT distribution in marine sediments. Here, we use the current proxy insights to (re-)assess the reliability of the isoGDGT-based SST signal in 69 newly analyzed and 242 reanalyzed sediments at Ocean Drilling Program (ODP) Site 1172 (East Tasman Plateau, Australia) following state-of-the-art chromatographic techniques. We compare our results with paleoenvironmental and paleoclimatologic reconstructions based on dinoflagellate cysts. The resulting ∼ 130 kyr resolution Maastrichtian–Oligocene SST record based on the TetraEther indeX of tetraethers with 86 carbon atoms (TEX 86) confirms previous conclusions of anomalous warmth in the early Eocene SW Pacific and remarkably cool conditions during the mid-Paleocene. Dinocyst diversity and assemblages show a strong response to the local SST evolution, supporting the robustness of the TEX 86 record. Soil-derived branched GDGTs stored in the same sediments are used to reconstruct mean annual air temperature (MAAT) of the nearby land using the Methylation index of Branched Tetraethers with 5-methyl bonds (MBT' 5me) proxy. MAAT is consistently lower than SST during the early Eocene, independent of the calibration chosen. General trends in SST and MAAT are similar, except for (1) an enigmatic absence of MAAT rise during the Paleocene–Eocene Thermal Maximum and Middle Eocene Climatic Optimum, and (2) a subdued middle–late Eocene MAAT cooling relative to SST. Both dinocysts and GDGT signals suggest a mid-shelf depositional environment with strong river runoff during the Paleocene–early Eocene progressively becoming more marine thereafter. This trend reflects gradual subsidence and more pronounced wet/dry seasons in the northward-drifting Australian hinterland, which may also explain the subdued middle Eocene MAAT cooling relative to that of SST. The overall correlation between dinocyst assemblages, marine biodiversity and SST changes suggests that temperature exerted a strong influence on the surface-water ecosystem. Finally, we find support for a potential temperature control on compositional changes of branched glycerol monoalkyl glycerol tetraethers (brGMGTs) in marine sediments. It is encouraging that a critical evaluation of the GDGT signals confirms that most of the generated data are reliable. However, this also implies that the high TEX 86 -based SSTs for the Eocene SW Pacific and the systematic offset between absolute TEX 86 -based SST and MBT' 5me -based MAAT estimates remain without definitive explanation. [ABSTRACT FROM AUTHOR]

We describe an experimental approach for achieving an optimal black background for scanning electron photomicrographs of small samples with elaborate and intricate structures. Specimens of the highly ornate, 66-million-year-old chorate dinoflagellate cyst species Cannosphaeropsis franciscana were selected as the subject of this study. Photomicrographs collected following standard aluminum stub surface placement were compared to those taken of specimens mounted using a novel pin-and-pedestal method. This simplistic mounting technique minimizes the need for post-production image editing and extraneous background removal. [ABSTRACT FROM AUTHOR]

This paper presents the diatom and palynomorph data from a sediment trap deployed in the northern part of the East Barents Sea for an annual cycle from August 2017 to August 2018. The average monthly fluxes of diatoms and dinoflagellate cysts in the photic layer of the northeastern part of the Barents Sea varies from 10.4 × 103 to 640.8 × 103 valves m−2 day−1 and from 0.3 × 103 to 90.0 × 103 cysts m−2 day−1, respectively. Their fluxes are related to the low irradiance of the photic layer during the sea-ice cover period, dominance of southward currents, modern climate, and nepheloid layer conditions. Based on redundancy analysis of the relationship between the fluxes of diatoms and dinoflagellate cysts and organic carbon fluxes, sea-ice covers, and the seasonal cycle of light availability we determined the following. First, sea-ice-associated diatoms and dinocysts are exported to the sediment trap from the melting sea ice with a two-week delay. Second, the appearance of freshwater diatoms and green algae in the sinking material accumulating from March 2018 to July 2018 is also related to the melting of sea ice. And third, the presence of Coscinodiscus radiatus, C. perforatus, Shionodiscus oestrupii and Operculodinium centrocarpum in the diatoms and dinocysts species composition throughout the year indicates the advection of Atlantic waters into the Barents Sea up to 80° N.