The fluviatile Bristol Elv Formation, a new Middle Jurassic lithostratigraphic unit from Traill Ø, North-East Greenland

A new lithostratigraphic unit, the Bristol Elv Formation, is erected in this paper. It is only known from Traill Ø, East Greenland, where it unconformably overlies Triassic redbeds of the Fleming Fjord Formation and is overlain by lithologically similar shallow marine Upper Bajocian sandstones of the Pelion Formation. The age of the formation is not well constrained but is probably Early Bajocian. The Bristol Elv Formation is at least 155 m thick and consists of conglomerates, coarse-grained pebbly sandstones and subordinate mudstones, deposited in braided rivers. A finer-grained lacustrine/floodplain unit, c. 37 m thick, is interbedded with the fluvial sandstones at one locality. Deposition of the fluvio-lacustrine Bristol Elv Formation marks a major change in basin configuration and drainage patterns, reflecting the onset of the important, protracted Middle–Late Jurassic rift event in East Greenland

A new Middle–Upper Jurassic succession on Hold with Hope, North-East Greenland

A succession of marine, Jurassic sediments was recently discovered on Hold with Hope, North-East Greenland. The discovery shows that the area was covered by the sea during Middle–Late Jurassic transgressive events and thus adds to the understanding of the palaeogeography of the area. The Jurassic succession on northern Hold with Hope is exposed in the hangingwalls of small fault blocks formed by rifting in Late Jurassic – Early Cretaceous times. It unconformably overlies Lower Triassic siltstones and sandstones and is overlain by Lower Cretaceous coarse-grained sandstones with an angular unconformity. The succession is up to 360 m thick and includes sandstones of the Lower–Upper Callovian Pelion and Middle–Upper Oxfordian Payer Dal Formations (Vardekløft Group) and heteroliths and mudstones of the Upper Oxfordian – Lower Kimmeridgian Bernbjerg Formation (Hall Bredning Group). The Pelion Formation includes the new Spath Plateau Member (defined herein). The palaeogeographic setting was a narrow rift-controlled embayment along the western margin of the rifted Jurassic seaway between Greenland and Norway. It was open to marine circulation to the south as indicated by the distribution and lateral facies variations and a dominant south-westwards marine palaeocurrent direction. The Pelion and Payer Dal Formations represent upper shoreface and tidally influenced delta deposits formed by the migration of dunes in distributary channels and mouthbars over the delta front. The boundary between the two formations is unconformable and represents a Late Callovian – Middle Oxfordian hiatus. It is interpreted to have formed by subaerial erosion related to a sea-level fall combined with minor tilting of fault blocks and erosion of uplifted block crests. In Late Jurassic time, the sand-rich depositional systems of the Pelion and Payer Dal Formations drowned and offshore transition – lower shoreface heteroliths and offshore mudstones of the Bernbjerg Formation accumulated. The fault block crest forming the eastern basin margin was inundated by a rise in relative sea level. Major fault activity probably occurred in latest Jurassic – Early Cretaceous times when the major fault block originally defining the Hold with Hope basin was split into smaller blocks

Jurassic dinoflagellate cyst stratigraphy of Hold with Hope, North-East Greenland

Dinoflagellate cysts of the Middle–Upper Jurassic succession on northern Hold with Hope have been studied in order to establish a biostratigraphic framework and to date the succession. The Pelion Formation is characterised by abundant Chytroeisphaeridia hyalina and Sentusidinium spp., with some Ctenidodinium thulium and Paragonyaulacysta retiphragmata in the lower part. Mendicodinium groenlandicum appears higher in the formation followed by Trichodinium scarburghense in the upper part. The succeeding Payer Dal Formation contains Scriniodinium crystallinum, Rigaudella aemula and Leptodinium subtile in the lower part and Dingodinium jurassicum and Prolixosphaeridium granulosum in the uppermost part. The Bernbjerg Formation contains abundant Sirmiodinium grossii and Gonyaulacysta jurassica. Adnatospahaeridium sp., Cribroperidinium granuligerum, Glossodinium cf. dimorphum and Scriniodinium irregulare appear in the lower part of the formation, followed by Avellodinium spp. in the highest part. The dinoflagellate cyst assemblages in the Pelion Formation indicate an Early–Late Callovian age (C. apertum – P. athleta Chronozones). This is supported by ammonites in the lower part of the formation, which refer to the C. apertum and P. koenigi Chronozones. A significant hiatus, from Late Callovian to Middle Oxfordian, is present between the Pelion Formation and the overlying Payer Dal Formation. The age of the Payer Dal Formation is Middle Oxfordian to earliest Late Oxfordian (C. tenuiserratum – A. glosense Chronozones). The Payer Dal Formation is conformably overlain by the Bernbjerg Formation of Late Oxfordian to possibly earliest Kimmeridgian age (A. glosense – P. baylei Chronozones). The A. glosense Chronozone is also documented by abundant ammonites in the lowermost part of the formation

Jurassic syn-rift sedimentation on a seawards-tilted fault block, Traill Ø, North-East Greenland

Middle–Late Jurassic rifting in East Greenland was marked by westwards tilting of wide fault blocks bounded by major N–S-trending east-dipping synthetic faults. The syn-rift successions thicken westwards towards the faults and shallow marine sandstones show mainly southwards axial transport directions. An exception to this general pattern is found in south-east Traill Ø, which constitutes the E-tilted Bjørnedal Block, which is bounded to the west by the westwards-dipping antithetic Vælddal Fault. The stratigraphic development of the Jurassic succession on this block shows important differences to the adjacent areas reflecting a different tectonic development. Shallow marine sand seems initially to have filled accommodation space of the immediately adjacent block to the west. This block subsequently acted as a bypass area and much of the sediment was spilled eastwards onto the hangingwall of the east-dipping Bjørnedal Block. The succession on the Bjørnedal Block shows an eastwards proximal–distal decrease in sandstone– mudstone ratio, reflecting increasing water depth and progressive under-filling of the subbasin towards the east in agreement with the dip direction of the fault block. The transverse, mainly south-eastwards palaeocurrents, the eastwards increase in water depths and decrease in sandstone–mudstone ratio on the Bjørnedal Block are at variance with the standard picture of west-tilted blocks with southwards-directed palaeocurrents and decrease in grain size. Earlier palaeogeographic reconstructions have to be modified to account for the east-dipping hangingwall and different stratigraphic development of the area. The sea was thus open towards the east and there is no direct indication of a barrier or shoal east of Traill Ø

Distribution of porosity-preserving microquartz coatings in sandstones, Upper Jurassic Danish Central Graben

High porosity is a key factor for good reservoir sandstones for both hydrocarbon and geothermal energy exploitation. The porosity of sandstones generally decreases with increased burial depth due to compaction and cementation. However, some sandstones in the North Sea show higher porosity than expected for their burial depth, due to the presence of micro­quartz coatings (e.g. Aase et al. 1996; Hendry & Trewin 1995; Jahren & Ramm 2000; Maast et al. 2011). Siliceous sponge spicules have been documented to be an internal source of silica that promotes microquartz coatings (e.g. Hendry & Trewin 1995; Aase et al. 1996). Siliceous sponge spicules, the solid ‘skeleton’ of sponges, consist of opal-A and will dissolve when exposed to higher temperatures, thereby causing supersaturation of the formation water with respect to opal-CT and quartz, resulting in nucleation of numerous small (1–5 µm) quartz crystals (Williams et al. 1985; Hendry & Trewin 1995). To predict reservoir quality it is important to understand the distribution of porosity-preserving microquartz in clastic deposits, and yet this is still poorly understood. To address this, our study presents petrographical analyses of cored sandstone sections from wells of various depositional environments, including  back-barrier, estuarine, shoreface and gravity flows, as well as various present-day burial depths across the Danish Central Graben.  &nbsp

Data centre opportunities in the Nordics : An analysis of the competitive advantages

The Nordic region attracts an increasing level of significant investments in new data centres. This seems to be no coincidence as the Nordics scores comparatively higher on factors such as "Reliable power supply", "Low energy prices", "Political stability", "Faster time-to-market" and "Abundance of energy and other resources" compared to more traditional European data centre regions. All factors that are deemed most important by data centre investors. This report estimates that the Nordics by 2025 could attract annual data centre construction investments in the order of EUR 2-4.3 bn. by 2025. This is based on the forecast of the future demand worldwide for data centre services – as well as the strong value proposition of the Nordic countries towards large datacenter investments