ABSTRACT Vitrinite reflectance (R r ) data, combined with structural field evidence, allow insights into the thermal and tectonic history of North Greenland. During the tectonism at the Cretaceous–Paleocene boundary, the thermal imprint varies considerably, mostly controlled by active fault zones. The Upper Cretaceous sequences along the Harder Fjord Fault Zone show R r values between ~3.2% (Frigg Fjord area) and ~2.1% (Depotbugt area). Along the Trolle Land Fault Zone, R r varies between 1.3% and 2.9% in the Herlufsholm Strand area, and between 1.6% and 2.2% in the Kilen area. These maturity variations along regional fault zones are connected with varying deformation intensity and explained by unequal conductive heat flow. In the Kap Washington Group, the high coal rank attaining 5.4% R r is associated with ductile deformation, and is additionally influenced by magmatic activity, i.e., convective heat flow. The coalification is low in regions a greater distance away from active faults, e.g., in Lower Cretaceous sediments of Herluf Trolle Land with ~0.5% R r . The Paleogene Thyra Ø Formation was deposited following deformation and thermal imprint at the Cretaceous–Paleogene boundary. It remained undeformed and shows a reduced R r of ~0.55%, reflecting burial thermal imprint. A later thermal event (known from the literature) that affected Mesozoic sediments, and possibly also locally Paleogene sediments close to the continental margin, is assumed to be related to heat flow from the active plate boundary between northeast Greenland and Svalbard. Based on detailed geochemical and mineralogical studies, thin, yellowish jarosite-bearing, clayey horizons within the Thyra Ø Formation are interpreted to probably originate from volcanic ashes erupted during the first stage of the opening of the North Atlantic.

ABSTRACT Anatomical analyses of fossil woods, supplemented by information from coal petrographic investigations, provide data for reconstructing the Cretaceous–Paleogene, mostly swampy woodland vegetation of the high latitudes. This paper is focused on the taxonomic description of conifers that have been recovered from a number of plant fossil Lagerstätten in Nathorstland, Yukon North Slope–western Mackenzie Delta, Ellesmere Island, northern Trolleland, and Kotel’nyi Island. The investigation revealed a relatively low taxonomic diversity. Wood-anatomical identification of Taxodioxylon vanderburghii provides evidence for the genus Metasequoia . The determination of Glyptostroboxylon cf. rudolphii demonstrates the most likely presence of Glyptostrobus , and the genus Cunninghamia is proved by the identification of Glyptostroboxylon tenerum . Moreover, this first evidence of Cunninghamia in the high latitudes establishes this plant as an “Arctic conifer.” Piceoxylon laricinoides (Høeg) comb. nov., a new combination, is proposed for a fossil wood species that represents the genus Larix . Fossils identified as Protopiceoxylon woods, Protopiceoxylon sp., and Protopiceoxylon yukonense represent the extinct gymnospermous Protopinaceae group. A fossil forest from the Split Lake Lagerstätte focusing on the habitus of in situ trunks and stumps was reconstructed. The vegetation encompasses a succession with three stages, an Equisetum reed facies, a Metasequoia swamp forest facies, and a Larix swamp forest facies. The taxonomic investigation suggests a widely distributed zone of vegetation with various conifers in the high latitudes. The lignite samples are characterized by predominantly woody (xylite) tissues with well-preserved, mummified stems and roots and a variable content of liptinite macerals, mostly resinite and suberinite. The intensive yellow fluorescent textinite of characteristic zoned structures and distinct microspores was observed in all investigated lignites.

Abstract This paper considers the lithospheric structure and evolution of the wider Barents–Kara Sea region based on the compilation and integration of geophysical and geological data. Regional transects are constructed at both crustal and lithospheric scales based on the available data and a regional three-dimensional model. The transects, which extend onshore and into the deep oceanic basins, are used to link deep and shallow structures and processes, as well as to link offshore and onshore areas. The study area has been affected by numerous orogenic events in the Precambrian–Cambrian (Timanian), Silurian–Devonian (Caledonian), latest Devonian–earliest Carboniferous (Ellesmerian–svalbardian), Carboniferous–Permian (Uralian), Late Triassic (Taimyr, Pai Khoi and Novaya Zemlya) and Palaeogene (Spitsbergen–Eurekan). It has also been affected by at least three episodes of regional-scale magmatism, the so-called large igneous provinces: the Siberian Traps (Permian–Triassic transition), the High Arctic Large Igneous Province (Early Cretaceous) and the North Atlantic (Paleocene–Eocene transition). Additional magmatic events occurred in parts of the study area in Devonian and Late Cretaceous times. Within this geological framework, we integrate basin development with regional tectonic events and summarize the stages in basin evolution. We further discuss the timing, causes and implications of basin evolution. Fault activity is related to regional stress regimes and the reactivation of pre-existing basement structures. Regional uplift/subsidence events are discussed in a source-to-sink context and are related to their regional tectonic and palaeogeographical settings.