Search

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.

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

One active journal. Fourteen legacy titles. More than 3000 articles published since 1893 – some digitised, some not. One full-time member of staff. A small team of dedicated geoscientists. Limited budget. PlanS. Open-source journal software. If these are the ingredients, what is the recipe? Like many surveys, the Geological Survey of Denmark and Greenland (GEUS) has a long history of publishing. Our full catalogue of titles extends back to 1893 and our current title, GEUS Bulletin (www.geusbulletin.org; formerly Geological Survey of Denmark and Greenland Bulletin), has been active since 2003. Our journals have always been grassroots initiatives – run by scientists, for scientists. But two years ago, amid the fast-changing demands of digital publishing, the Survey faced a quandary: should we continue publishing our own journal? At a time of rapid proliferation of journals for any discipline imaginable, what niche did a geographically-focused journal fill? What should we modernise? Could we relaunch as an online, diamond open-access journal on our existing budget? Could we implement more of the services our authors wanted and attract more authors beyond our traditional audience? Two years later, we have successfully re-launched our collection of journals, without increasing our overall budget. Using open-source solutions, we have transformed our print-focused publication workflow to a new online, open-access platform and data repository. We are currently migrating our entire back catalogue of legacy titles to the same platform. Although we only have visitor data for our new platform since November 2020, we can see early signs of increased article views (c. +82% in Nov–Dec 2020, compared with the same months in 2018 and 2019) and a jump in traffic from external websites like Google Scholar (from 5% before re-launch to 35% after re-launch). In this presentation, we present a recipe that we hope other geological surveys, societies and institutions can

Geothermal resources in the deep subsurface in many parts of Denmark have the potential to form a central component in the future Danish energy supply for district heating. Geothermal energy is sustainable and environmentally friendly and independent of climatic and seasonal variations, in contrast to solar and wind energy. Furthermore, geothermal plants may be integrated with other green energy supplies. The sandstone reservoirs from which the warm geothermal water is extracted may also act as temporary storage for excess heat e.g. from industrial production processes or from solar-heated water in summer periods when the demand for heating is low.

Climate changes preserved in sandstones are documented by comparing the sediment composition and early diagenetic changes in sandstones deposited during arid to semi-arid conditions, the Skagerrak Formation, with sandstones of the Gassum Formation deposited in a humid well-vegetated environment. The study area covers the easternmost part of the Norwegian–Danish Basin, for which the Fennoscandian Shield functioned as sediment source area. The depositional environments of the formations, their distribution and burial depths are well-constrained, facilitating a comprehensive petrographical and geochemical study complemented by porosity and permeability measurements of cores widely distributed in the basin (1700 to 5900 m burial depth). The Skagerrak Formation had an immature composition with more abundant feldspar, rock fragments and a larger variability in the heavy mineral assemblage when compared to the Gassum Formation, which was characterized by quartz and more stable heavy minerals. The arid to semi-arid climate led to early oxidizing conditions under which abundant iron-oxide/hydroxide coatings formed, while the evaporative processes occasionally resulted in caliche and gypsum precipitation. Under the humid climate, kaolinite precipitated due to leaching of feldspar and mica, and the abundant organic matter caused reducing conditions, which led to other Fe-rich phases, i.e. pyrite, Fe-chlorite and siderite. The inherited early diagenetic pore fluids and mineral assemblage also affect the mineral changes occurring during deeper burial, so dolomite preferentially formed in the sandstones deposited in an arid environment, while ankerite characterizes sandstones deposited under humid conditions. In addition to climate-induced burial diagenetic changes, there are also temperature-dependent phases, such as illite and quartz cement. Despite the same sediment source area remaining active during the entire period, the sediments that reached the Norwegian–Danish Basin

Zircon U–Pb geochronometry, heavy mineral analyses and conventional seismic reflection data were used to interpret the provenance of the Lower Triassic Bunter Sandstone Formation. The succession was sampled in five Danish wells in the northern part of the North German Basin. The results show that sediment supply was mainly derived from the Ringkøbing-Fyn High situated north of the basin and from the Variscan belt located south of the basin. Seismic reflection data document that the Ringkøbing-Fyn High was a local barrier for sediment transport during the Early Triassic. Hence, the Fennoscandian Shield did not supply much sediment to the basin as opposed to what was previously believed. Sediment from the Variscan belt was transported by wind activity across the North German Basin when it was dried out during deposition of the aeolian part of the Volpriehausen Member (lower Bunter Sandstone). Fluvial sand was supplied from the Ringkøbing-Fyn High to the basin during precipitation events which occurred most frequently when the Solling Member was deposited (upper Bunter Sandstone). Late Neoproterozoic to Carboniferous zircon ages predominate in the Volpriehausen Member where the dominant age population with a peak age of 337 Ma corresponds to the culmination of Variscan high-grade metamorphism, whereas a secondary age population with a peak at 300 Ma matches the timing of volcanism and magmatism at the Carboniferous/Permian boundary in the northern Variscan belt. Parts of the basement in the Ringkøbing-Fyn High were outcropping during the Early Triassic and zircon ages similar to this Mesoproterozoic basement are present in the Bunter Sandstone. The heavy mineral assemblage of the Solling Member is uniform and has a high garnet content compared to the contemporaneous sediments in the Norwegian-Danish Basin and in the southern part of the North German Basin. This finding confirms that a local source in the Ringkøbing-Fyn High supplied most of the fluvial sediment in the

Interpretations of seismic profiles, gamma-ray logs and sediment descriptions were used to classify seven facies in Miocene fluvio-deltaic deposits ofDenmark. An impartial approach was adopted by not including analytical data in the facies definition. This approach allowed identification of significant differences between facies, where each fluvio-deltaic facies can be distinguished by integrating geochemistry and mineralogy through a sedimentary succession. Variations in the heavy mineral assemblage between facies are caused primarily by sorting of hydraulically equivalent grains. Decreasing grain size of quartz and heavy minerals from the channel facies towards the delta shoreface facies and further along the coast to the spit shoreface facies is associated with an increase in sorting and textural maturity. This trend is related to longshore drift. Increasing heavy mineral grain size is found from the delta slope facies offshore to the delta toe and shelf facies. This trend is interpreted as a result of sorting by turbidity currents. The mixed origin of the transgressive lag facies is shown by the poorer sorting in this facies. By indicating the amount of alteration the sediments have been exposed to, the Ti-mineral maturity has proven useful in characterizing the facies. This systematic approach of tying depositional environments to a well-calibrated sequence stratigraphic model has generated analytical results which are valid as reference levels for future facies identifications.