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Over long stretches of the north-east coast of Qeqertarsuaq (Disko), the sediments in the Nuussuaq Basin and their relations to the volcanic rocks are concealed beneath numerous landslides. Two cores south of Qullissat drilled by Falconbridge Ltd in 1994, targeting a native-iron-bearing igneous body assumed to be a sill, present well-preserved sections through the hidden succession. We have dated the sediments in the cores palynologically. The lower part comprises 115 m of deltaic deposits, including coal seams, of the Cretaceous Atane Formation, Qilakitsoq Member (late Turonian to early Coniacian age), which has not been recorded on Disko before. The two cores and five short coastal cliff sections are mutually correlatable and correlate further to the coal seams earlier mined at Qullissat; the coals are hereby dated for the first time. The Cretaceous rocks are overlain by 15 m of marine deposits, mainly mudstones, of the Danian Eqalulik Formation, with a hiatus of c. 24 million years. The igneous body of native-iron-bearing basaltic andesite has a thick, red-oxidised, vesiculated and brecciated top zone and is interpreted as a subaerial lava flow belonging to the Asuk Member of the Vaigat Formation. The flow has run perhaps up to 20 km from the eruption site to the sea, where it ponded and attained a thickness of 138 m, the thickest lava flow in the West Greenland Basalt Group. The flow is overlain by 22 m of non-marine sandstones and mudstones of the Atanikerluk Formation. The core correlation indicates the existence of a fault with c. 90 m vertical displacement between the two drill sites. The structural relations of the various parts of the Atane Formation along the north-east coast of Disko necessitate the assumption of another hidden, prevolcanic fault south of Qullissaaqqat.

Over long stretches of the north-east coast of Qeqertarsuaq (Disko), the sediments in the Nuussuaq Basin and their relations to the volcanic rocks are concealed beneath numerous landslides. Two cores south of Qullissat drilled by Falconbridge Ltd in 1994, targeting a native-iron-bearing igneous body assumed to be a sill, present well-preserved sections through the hidden succession. We have dated the sediments in the cores palynologically. The lower part comprises 115 m of deltaic deposits, including coal seams, of the Cretaceous Atane Formation, Qilakitsoq Member (late Turonian to early Coniacian age), which has not been recorded on Disko before. The two cores and five short coastal cliff sections are mutually correlatable and correlate further to the coal seams earlier mined at Qullissat; the coals are hereby dated for the first time. The Cretaceous rocks are overlain by 15 m of marine deposits, mainly mudstones, of the Danian Eqalulik Formation, with a hiatus of c. 24 million years. The igneous body of native-iron-bearing basaltic andesite has a thick, red-oxidised, vesiculated and brecciated top zone and is interpreted as a subaerial lava flow belonging to the Asuk Member of the Vaigat Formation. The flow has run perhaps up to 20 km from the eruption site to the sea, where it ponded and attained a thickness of 138 m, the thickest lava flow in the West Greenland Basalt Group. The flow is overlain by 22 m of non-marine sandstones and mudstones of the Atanikerluk Formation. The core correlation indicates the existence of a fault with c. 90 m vertical displacement between the two drill sites. The structural relations of the various parts of the Atane Formation along the north-east coast of Disko necessitate the assumption of another hidden, prevolcanic fault south of Qullissaaqqat.

The organic matter content of marine sediments is often used to infer past changes in ocean conditions. However, the organic carbon pool preserved in coastal sediments is a complex mixture derived from different sources and may not reflect in situ processes. In this study, we combine taxonomic identification of reworked palynomorphs with pyrolysis organic geochemistry and reflected-light organic petrographic microscopy to investigate the provenance, composition and preservation of organic matter in a marine sediment core retrieved from the NE Greenland shelf. Our study reveals continuous yet variable input of land-derived organic carbon to the marine environment throughout the late Younger Dryas–Holocene, with the highest input of inert carbon in the late Younger Dryas. Although the sediments contain some recent marine palynomorphs, there is no other evidence of fresh marine organic carbon. In contrast, our results indicate that these shelf sediments represent a significant sink of recycled organic carbon. The results of pyrolysis geochemistry revealed that ~90% of the total organic carbon in the sediments is inert. The organic petrography analyses revealed that >70–84% of the organic carbon in the sediment core is terrigenous. Reworked dinoflagellate cysts showed a continuous provenance of Cretaceous land-derived material, most likely from the nearby Clavering Island. Our study points to the importance of constraining the organic matter origin, composition and preservation in marine sediments to achieve more accurate palaeoenvironmental reconstructions based on organic proxies.

The Ikorfat Fault zone in northern Nuussuaq, Central West Greenland, has preserved a hitherto unknown succession of Upper Cretaceous marine mudstones referred to the Itilli Formation, which have been removed by erosion on the footwall block and buried deeply below sea-level on the hanging-wall block. Outcrops in the fault zone provide new data on sedimentology, palynology, stable carbon isotopes and organic geochemistry in the lower part of the Itilli Formation. A new, detailed geological map of the study area is based on digital photogrammetry. Marine organic walled dinoflagellate cysts (dinocysts) demonstrate a late Cenomanian–Turonian age, coeval with the Oceanic Anoxic Event 2 (OAE2) and link the Nuussuaq Basin with the Baffin Bay and Sverdrup Basins. The Ikorfat Fault zone is part of the eastern boundary fault of the Nuussuaq Basin. Lower Campanian listric faults truncate the footwall block. Subsidence along steep normal faults continued during deposition of the volcanic Vaigat Formation of Danian to Selandian age. The downthrow of the hanging-wall block was around 2.5 km.

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.

The organic matter content of marine sediments is often used to infer past changes in ocean conditions. However, the organic carbon pool preserved in coastal sediments is a complex mixture derived from different sources and may not reflect in situ processes. In this study, we combine taxonomic identification of reworked palynomorphs with pyrolysis organic geochemistry and reflected-light organic petrographic microscopy to investigate the provenance, composition and preservation of organic matter in a marine sediment core retrieved from the NE Greenland shelf. Our study reveals continuous yet variable input of land-derived organic carbon to the marine environment throughout the late Younger Dryas–Holocene, with the highest input of inert carbon in the late Younger Dryas. Although the sediments contain some recent marine palynomorphs, there is no other evidence of fresh marine organic carbon. In contrast, our results indicate that these shelf sediments represent a significant sink of recycled organic carbon. The results of pyrolysis geochemistry revealed that ~90% of the total organic carbon in the sediments is inert. The organic petrography analyses revealed that >70–84% of the organic carbon in the sediment core is terrigenous. Reworked dinoflagellate cysts showed a continuous provenance of Cretaceous land-derived material, most likely from the nearby Clavering Island. Our study points to the importance of constraining the organic matter origin, composition and preservation in marine sediments to achieve more accurate palaeoenvironmental reconstructions based on organic proxies.

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.

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.

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

The paleoenvironmental and paleogeographic development of the Norwegian–Greenland seaway remains poorly understood, despite its importance for the oceanographic and climatic conditions of the Paleocene–Eocene greenhouse world. Here we present analyses of the sedimentological and paleontological characteristics of Paleocene–Eocene deposits (between 63 and 47 million years old) in northeast Greenland, and investigate key unconformities and volcanic facies observed through seismic reflection imaging in offshore basins. We identify Paleocene–Eocene uplift that culminated in widespread regression, volcanism, and subaerial exposure during the Ypresian. We reconstruct the paleogeography of the northeast Atlantic–Arctic region and propose that this uplift led to fragmentation of the Norwegian–Greenland seaway during this period. We suggest that the seaway became severely restricted between about 56 and 53 million years ago, effectively isolating the Arctic from the Atlantic ocean during the Paleocene–Eocene thermal maximum and the early Eocene.

Large structural highs and sedimentary basins are identified from mapping of the West Greenland continental margin from the Labrador Sea to the Baffin Bay. We present a new tectonic elements map and a map of thickness from the seabed to the basement of the entire West Greenland margin. In addition, a new stratigraphic scheme of the main lithologies and tectonostratigraphy based on ties to all offshore exploration wells is presented together with seven interpreted seismic sections. The work is based on interpretation of more than 135 000 km of 2D seismic reflection data supported by other geophysical data, including gravity-and magnetic data and selected 3D seismic data, and is constrained by correlation to wells and seabed samples. Eight seismic mega-units (A–H) from the seabed to the basement, related to distinct tectonostratigraphic phases, were mapped. The oldest units include pre-rift basins that contain Proterozoic and Palaeozoic successions. Cretaceous syn-rift phases are characterised by development of large extensional fault blocks and basins with wedge-shaped units. The basin strata include Cretaceous and Palaeogene claystones, sandstones and conglomerates. During the latest Cretaceous, Paleocene and Eocene, crustal extension followed by oceanic crust formation took place, causing separation of the continental margins of Greenland and Canada with north-east to northward movement of Greenland. From Paleocene to Eocene, volcanic rocks dominated the central West Greenland continental margin and covered the Cretaceous basins. Development of the oceanic crust is associated with compressional tectonics and the development of strike-slip and thrust faults, pull-apart basins and inversion struc-tures, most pronounced in the Davis Strait and Baffin Bay regions. During the late Cenozoic, tectonism diminished, though some intra-plate vertical adjustments occurred. The latest basin development was characterised by formation of thick Neogene to Quaternary marine succ

The Late Cretaceous Oceanic Anoxic Event 2 (OAE2) represents a major perturbation of the global carbon cycle caused by the widespread deposition of organic-rich black shales. Although the paleoceanographic response and the spatial extent of bottom-water anoxia in low and mid-paleolatitudes are reasonably well constrained for OAE2, similar data from high paleolatitudes are lacking. Here, we present palynostratigraphy and organic-carbon isotope stratigraphy from the Sverdrup Basin, Axel Heiberg Island (Canada). It is shown that episodes of high marine organic-carbon burial at paleolatitudes of ∼70°N is contemporaneous with the widely observed occurrence of black shale deposition during OAE2. Paleontological, lithological, and geochemical data indicate normal marine conditions with persistent anoxic bottom waters during OAE2. The results imply that the high marine primary productivity pulse during OAE2 may have caused massive organic-carbon burial on the Arctic shelf in general, with important implications for hydrocarbon source-rock distribution in the Arctic region.

The Late Cretaceous Oceanic Anoxic Event 2 (OAE2) represents a major perturbation of the global carbon cycle caused by the widespread deposition of organic-rich black shales. Although the paleoceanographic response and the spatial extent of bottom-water anoxia in low and mid-paleolatitudes are reasonably well constrained for OAE2, similar data from high paleolatitudes are lacking. Here, we present palynostratigraphy and organic-carbon isotope stratigraphy from the Sverdrup Basin, Axel Heiberg Island (Canada). It is shown that episodes of high marine organic-carbon burial at paleolatitudes of ∼70°N is contemporaneous with the widely observed occurrence of black shale deposition during OAE2. Paleontological, lithological, and geochemical data indicate normal marine conditions with persistent anoxic bottom waters during OAE2. The results imply that the high marine primary productivity pulse during OAE2 may have caused massive organic-carbon burial on the Arctic shelf in general, with important implications for hydrocarbon source-rock distribution in the Arctic region.

Cretaceous oceanic anoxic events (OAEs) have been studied in detail during the last decades. OAE2 is of particular interest as it reflects one of the largest perturbations of the global carbon cycle in the Mesozoic. It is characterised by a widespread deposition of organic rich sediments which is reflected by a positive carbon isotope excursion (CIE) in the terrestrial and marine record. Whereas the paleoredox conditions in low and mid-paleolatitudes are well constrained for OAE2, data from high paleolatitudes are still scarce. The paleoceanographic response at high paleolatitudes during OAE2 is here characterized by samples from Axel Heiberg Island in Canada. Preliminary palynological analyses indicate a Late Cenomanian!Coniacian age for the section. Bulk organic carbon isotope data have been corrected using the hydrogen index (Rock Eval pyrolysis) to account for changes in organic matter sourcing. Our corrected isotope record correlates in detail with the European carbonate reference curve and confirms our biostratigraphic model. Iron speciation (FeHR/FeT and FePy/ FeHR) data point to anoxic but non-euxinic conditions at high paleolatitudes during OAE2. Furthermore the Sverdrup Basin was intermittently suboxic to anoxic (ferruginous) throughout most of the latest Cenomanian–Coniacian. Despite very high TOC (>10%) and hydrogen index values, molybdenum concentrations are relatively low during OAE2 but increase after the event. This suggests a global drawdown of the seawater molybdenum reservoir caused by the widespread extent of ocean anoxia/euxinia in the Cretaceous oceans during OAE2.

Cretaceous oceanic anoxic events (OAEs) have been studied in detail during the last decades. OAE2 is of particular interest as it reflects one of the largest perturbations of the global carbon cycle in the Mesozoic. It is characterised by a widespread deposition of organic rich sediments which is reflected by a positive carbon isotope excursion (CIE) in the terrestrial and marine record. Whereas the paleoredox conditions in low and mid-paleolatitudes are well constrained for OAE2, data from high paleolatitudes are still scarce. The paleoceanographic response at high paleolatitudes during OAE2 is here characterized by samples from Axel Heiberg Island in Canada. Preliminary palynological analyses indicate a Late Cenomanian!Coniacian age for the section. Bulk organic carbon isotope data have been corrected using the hydrogen index (Rock Eval pyrolysis) to account for changes in organic matter sourcing. Our corrected isotope record correlates in detail with the European carbonate reference curve and confirms our biostratigraphic model. Iron speciation (FeHR/FeT and FePy/ FeHR) data point to anoxic but non-euxinic conditions at high paleolatitudes during OAE2. Furthermore the Sverdrup Basin was intermittently suboxic to anoxic (ferruginous) throughout most of the latest Cenomanian–Coniacian. Despite very high TOC (>10%) and hydrogen index values, molybdenum concentrations are relatively low during OAE2 but increase after the event. This suggests a global drawdown of the seawater molybdenum reservoir caused by the widespread extent of ocean anoxia/euxinia in the Cretaceous oceans during OAE2.

Cretaceous oceanic anoxic events (OAEs) have been studied in detail during the last decades. OAE2 is of particular interest as it reflects one of the largest perturbations of the global carbon cycle in the Mesozoic. It is characterised by a widespread deposition of organic rich sediments which is reflected by a positive carbon isotope excursion (CIE) in the terrestrial and marine record. Whereas the paleoredox conditions in low and mid-paleolatitudes are well constrained for OAE2, data from high paleolatitudes are still scarce. The paleoceanographic response at high paleolatitudes during OAE2 is here characterized by samples from Axel Heiberg Island in Canada. Preliminary palynological analyses indicate a Late Cenomanian!Coniacian age for the section. Bulk organic carbon isotope data have been corrected using the hydrogen index (Rock Eval pyrolysis) to account for changes in organic matter sourcing. Our corrected isotope record correlates in detail with the European carbonate reference curve and confirms our biostratigraphic model. Iron speciation (FeHR/FeT and FePy/ FeHR) data point to anoxic but non-euxinic conditions at high paleolatitudes during OAE2. Furthermore the Sverdrup Basin was intermittently suboxic to anoxic (ferruginous) throughout most of the latest Cenomanian–Coniacian. Despite very high TOC (>10%) and hydrogen index values, molybdenum concentrations are relatively low during OAE2 but increase after the event. This suggests a global drawdown of the seawater molybdenum reservoir caused by the widespread extent of ocean anoxia/euxinia in the Cretaceous oceans during OAE2.

Cretaceous oceanic anoxic events (OAEs) have been studied in detail during the last decades. OAE2 is of particular interest as it reflects one of the largest perturbations of the global carbon cycle in the Mesozoic. It is characterised by a widespread deposition of organic rich sediments which is reflected by a positive carbon isotope excursion (CIE) in the terrestrial and marine record. Whereas the paleoredox conditions in low and mid-paleolatitudes are well constrained for OAE2, data from high paleolatitudes are still scarce. The paleoceanographic response at high paleolatitudes during OAE2 is here characterized by samples from Axel Heiberg Island in Canada. Preliminary palynological analyses indicate a Late Cenomanian!Coniacian age for the section. Bulk organic carbon isotope data have been corrected using the hydrogen index (Rock Eval pyrolysis) to account for changes in organic matter sourcing. Our corrected isotope record correlates in detail with the European carbonate reference curve and confirms our biostratigraphic model. Iron speciation (FeHR/FeT and FePy/ FeHR) data point to anoxic but non-euxinic conditions at high paleolatitudes during OAE2. Furthermore the Sverdrup Basin was intermittently suboxic to anoxic (ferruginous) throughout most of the latest Cenomanian–Coniacian. Despite very high TOC (>10%) and hydrogen index values, molybdenum concentrations are relatively low during OAE2 but increase after the event. This suggests a global drawdown of the seawater molybdenum reservoir caused by the widespread extent of ocean anoxia/euxinia in the Cretaceous oceans during OAE2.