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Despite often being referred to as a ‘coolhouse climate’, the climate during the Miocene (23.03–5.33 Ma) was overall humid, warm and temperate. It was paced by orbitally driven cooler periods (the Oligocene–Miocene Transition and Mi-events) overprinted by a climatic optimum. Global cooling during the Late Miocene brought more arid conditions with climate seasonality, which varied across western Eurasia. Sedimentary archives from onshore Denmark comprise shallow marine siliciclastic deposits and discrete brown coal layers. Hence, they allow us to infer past climates and environments using both marine and terrestrial fossils. The backbone for Miocene stratigraphy and palaeoclimate reconstruction in the eastern North Sea Basin (present-day Denmark) is the Sønder (Sdr.) Vium sediment core, which penetrates a shallow marine succession and spans an interval from c. 22 to 8 Ma. Here, we present an improved age model for the core. During the Miocene, forested lowlands predominated in the eastern North Sea Basin. Coastal areas included rich riparian landscapes and delta areas of lignite-forming swamp forest. Compilations of existing proxy records (pollen, spores, leaves, plant fragments and the organic biomarkers alkenones and membrane lipids) collectively show that the climate here was warm and moist during the Early and Middle Miocene, while the Late Miocene was characterised by climate cooling and modernisation of the vegetation. The interval preceding the Miocene Climatic Optimum was already warm and moist, and the onset was not characterised by a significant increase in temperature and precipitation. Instead, the palynoflora indicates homogeneous vegetation and only a weak signal of warming shown by a minor increase of, for example, sabaloid palms and Mastixiaceae

Two fully cored boreholes, the Rødryggen-1 and the Brorson Halvø-1, were drilled in Wollaston Forland, North-East Greenland, in 2009 and 2010, respectively. The objective was to test the stratigraphic development of the Upper Jurassic – Lower Cretaceous mud-dominated succession in two different settings within the same fault block of a developing half-graben: centrally (Rødryggen-1 borehole) and near the uplifted crest of the rotating fault block (Brorson Halvø-1 borehole). The drilled deposits are equivalent to the principal petroleum source-rock sequence of the petrolifer-ous basins of North-West Europe, Siberia, and basins off eastern Canada and provide a new record of an important phase of marine deoxygenation in the proto-North Atlantic region.

The Oxfordian–Ryazanian was a period of widespread deposition of marine organic-rich mud-stones in basins formed during the early phases of the rifting that heralded the formation of the present-day North Atlantic. Occasionally, uninterrupted deposition prevailed for 20 million years or more. Today, mudstones of this time interval are found on the shelves bordering the North Atlantic and adjacent areas from Siberia to the Netherlands. Here, we report data on two fully cored boreholes from Wollaston Forland (North-East Greenland, approx. 74° N), which represent an uninterrupted succession from the upper Kimmeridgian to the Hauterivian. The boreholes record basin development at two different positions within an evolving halfgraben, located at the margin of the main rift, and thus partially detached from it. Although the overall depositional environment remained an oxygen-restricted deep-shelf setting, rifting-related changes can be followed through the succession. The Kimmeridgian was a period of eustatic highstand and records the incipient rifting with a transgressive trend straddling the transition to the lower Volgian by a gradual change from deposits with high levels of total organic carbon (TOC) and kerogen rich in allochthonous organic matter to deposits with lower TOC and a higher proportion of autochthonous organic matter. This is followed by a slight regressive trend with lower TOC and increased proportions of allochthonous organic matter until rifting culminated in the middle Volgian–Ryazanian, indicated by increasing autochthonous organic matter and higher TOC, which prevailed until basin ventilation occurred towards the end of the Ryazanian. The properties of the reactive kerogen fraction remained rather stable irrespective of TOC, underlining the effect of terrigenous matter input for TOC. These variations are also captured by biological markers and stable carbon isotopes. The deposits are very similar to equivalent successions elsewhere in the proto-N

Two shallow cores drilled in northern Wollaston Forland, North-East Greenland, provide a combined section covering the upper Kimmeridgian (Upper Jurassic) – Barremian (Lower Cretaceous) and comprising the Bernbjerg, Lindemans Bugt, Palnatokes Bjerg and Stratumbjerg Formations. A new lithostratigraphic unit, the Storsletten Member, is defined within the Lindemans Bugt For-mation. The black mudstone-dominated intervals are dated primarily by dinoflagellate cysts and ammonites, whereas the calcareous mudstones of the Palnatokes Bjerg Formation – sandwiched between the black mudstones – are dated by calcareous nannofossils. The stratigraphy demon-strates an almost complete succession in the Rødryggen-1 core, representing a deeper position in the basin, where the hiatus at the latest Jurassic rift climax predicted in previous models for the eastern Wollaston Forland Basin is absent. In contrast, the Brorson Halvø-1 core represents a position closer to a block crest where unconformities developed. In combination, the cores provide a key biostratigraphic reference section for the Jurassic–Cretaceous boundary interval in the Arctic.

Two drill cores spanning the Upper Jurassic – Lower Cretaceous succession in Wollaston Forland, North-East Greenland, offer an insight into mud accumulation in an evolving distal fault block. Previous studies have revealed the presence of long-lasting black mudstone accumulation extending through the oxygen-restricted early rift and rift climax phases (Bernbjerg and Lindemans Bugt Formations). Here, we present a detailed description of the sedimentary succession extending into the late syn-rift settings (Palnatokes Bjerg and Stratumbjerg Formations). The results indicate that the Kimmeridgian – lower Volgian early rift-phase was characterised by suspension settling and millimetre-scale event deposition in a tectonically affected, prodeltaic offshore setting. The event-related depositional processes are recorded by starved wave ripples, scour-and-fill structures, putative mud-floccule ripples and mud-dominated gravity-flow deposits. During the middle Volgian – Ryazanian rift climax, the depositional environment evolved into a narrow half-graben that was detached from the proximal depocentre flanking the deltaic coastline, itself dominated by coarse sediment. The correlative sedimentary facies in the detached half-graben are bioclastic and pyrite-rich black mudstones, which document suspension settling and gravity-flow or mass-wasting deposition in sub-storm wave-base slope and basin-floor environments. Black mudstone sedimentation ended abruptly in the late Ryazanian when the accumulation of condensed, bioturbated deep marine marls coincided with broader oceanographic reorganisation concomitant with waning rift activity in the west. Deposition of red bioclastic mudstones with a common gravity-flow component characterised the Hauterivian, potentially representing final draping of the submerged fault block crest. The top of the cored succession is demarcated by dark grey bioturbated mudstones of Barremian age, reflecting the onset of regionally continuous deep marin

“Doming–rifting–spreading” constitute the main phases of classical plate tectonics. The Middle–Upper Jurassic succession of East Greenland is interpreted as reflecting formation, deflation and onlap of a rift dome, similar to contemporaneous rift domes in the North Sea, Denmark and southern Sweden. The succession forms a northwards backstepping and onlapping early rift succession in the N–S oriented basin. Deposition ranged from coastal over shallow marine and slope sands, through offshore siltstones to deep basinal mudstones. An outlier on the island Geographical Society Ø fills an important gap in the documentation of the doming, deflation and progressive onlap. Bajocian deposition took place in a shallow marine shelf. This was followed in the late Oxfordian by slope and base-of-slope deposition. The backstepping succession onlaps progressively older rocks towards the north, illustrating the gradual deflation, erosion and onlap of the dome, constituting the early part of the doming–rifting–spreading phases of classical plate tectonics.

Since 1976 more than 25,000 Arctic sediment samples have been processed for their palynological, nannofossil, or microfossil content at the Geological Survey of Greenland (GGU) and the Geological Survey of Denmark (DGU); both institutes are now merged into the Geological Survey of Denmark and Greenland (GEUS). The samples represent nearly all ages from the Neoproterozoic to the Neogene, though dominated by the Mesozoic. A large proportion of the samples were processed for palynomorphs. Up to ten slides have been produced for each palynological sample and usually one slide is produced for each nannofossil and microfossil sample, making the GEUS collection one of the largest Arctic slide collections with more than 200,000 slides. All type specimens and some specimens illustrated in publications listed here have been assigned MGUH numbers (Museum Geologica Universitas Hafniensis) and are housed in the type collection of the Geological Museum of the University of Copenhagen, now part of the Natural History Museum of Denmark.

Odd palynomorphs are identified in sediments in a shallow core from the Rømø barrier island in the Danish Wadden Sea. The palynomorphs occur in five stratigraphic samples of lacustrine mud, peat and sand. The sand has a chaotic structure and was deposited by a tsunami associated with the Storegga slide in the North Atlantic Ocean, 8150 years ago. The palynomorphs are very common in the lower samples from in situ gyttja and peat and are less common in the overlying sand bed. Reworked lumps of peat occur in the sand and the palynomorphs are therefore also considered reworked into the sand during the tsunami event. The variable morphology of the palynomorphs is considered to represent the ontogeny as well as the specific morphology of fern annuli. The wall tissue of the sporangium is coherent with annulus cells and reveals the fern relationship. The tissue shows a characteristic succession of elongated, rectangular cells in the sporangium wall with stomium and annulus. The palynomorphs are interpreted as parts of annuli from sporangia of leptosporangiate ferns. The modern fern species Hemionitis glabella has a comparable sporangium morphology, and the palynomorphs are considered to come from a fern relative. Hemionitis is cosmopolitan but absent in Europe north of France. This annulus type and the derived palynomorph types have not been described from fossil material before.