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The increasing anthropogenic CO 2 forcing of the climate system calls for a better understanding of how polar ice sheets may respond to accelerating global warming. The sensitivity of the Greenland ice sheet to polar amplification, changes in ocean heat transport, and deteriorating perennial sea ice conditions makes the Northeast Greenland margin a pertinent location with respect to understanding the impact of climate change on ice sheet instability and associated sea level rise. Throughout the Cenozoic, ocean heat fluxes toward and along Northeast Greenland have been controlled by water mass exchanges between the Arctic and Atlantic oceans. A key element here is the current flow through oceanic gateways, notably the Fram Strait and the Greenland–Scotland Ridge. To gain a long-term (million-year) perspective of ice sheet variability in this region, it is essential to understand the broader context of ice–ocean–tectonic interactions. Coupling between the ice sheet, the subsurface, the ocean, and sea ice are readily observable today in Northeast Greenland, but geological records to illuminate long-term trends and their interplay with other parts of the global climate system are lacking. Consequently, the NorthGreen workshop was organized by the Geological Survey of Denmark and Greenland in collaboration with Aarhus (Denmark) and Stockholm (Sweden) universities in November 2022 to develop mission-specific platform (MSP) proposals for drilling the Northeast Greenland margin under the umbrella of the MagellanPlus Workshop Series Programme of the European Consortium for Ocean Research Drilling (ECORD). Seventy-one participants representing a broad scientific community discussed key scientific questions and primary targets that could be addressed through scientific drilling in Northeast Greenland. Three pre-proposals were initiated during the workshop targeting Morris Jesup Rise, the Northeast Greenland continental shelf, and Denmark Strait. [ABSTRACT FROM AUTHOR]

We compile and analyze all available geothermal heat flow measurements collected in and around Greenland into a new database of 419 sites and generate an accompanying spatial map. This database includes 290 sites previously reported by the International Heat Flow Commission (IHFC), for which we now standardize measurement and metadata quality. This database also includes 129 new sites, which have not been previously reported by the IHFC. These new sites consist of 88 offshore measurements and 41 onshore measurements, of which 24 are subglacial. We employ machine learning to synthesize these in situ measurements into a gridded geothermal heat flow model that is consistent across both continental and marine areas in and around Greenland. This model has a native horizontal resolution of 55 km. In comparison to five existing Greenland geothermal heat flow models, our model has the lowest mean geothermal heat flow for Greenland onshore areas. Our modeled heat flow in central North Greenland is highly sensitive to whether the NGRIP (North GReenland Ice core Project) elevated heat flow anomaly is included in the training dataset. Our model's most distinctive spatial feature is pronounced low geothermal heat flow (< 40 mW m -2) across the North Atlantic Craton of southern Greenland. Crucially, our model does not show an area of elevated heat flow that might be interpreted as remnant from the Icelandic plume track. Finally, we discuss the substantial influence of paleoclimatic and other corrections on geothermal heat flow measurements in Greenland. The in situ measurement database and gridded heat flow model, as well as other supporting materials, are freely available from the GEUS Dataverse (10.22008/FK2/F9P03L; Colgan and Wansing, 2021). [ABSTRACT FROM AUTHOR]

We compile, analyse and map all available geothermal heat flow measurements collected in and around Greenland into a new database of 419 sites and generate an accompanying spatial map. This database includes 290 sites previously reported by the International Heat Flow Commission (IHFC), for which we now standardize measurement and metadata quality. This database also includes 129 new sites, which have not been previously reported by the IHFC. These new sites consist of 88 offshore measurements and 41 onshore measurements, of which 24 are subglacial. We employ machine learning to synthesize these in situ measurements into a gridded geothermal heat flow model that is consistent across both continental and marine areas in and around Greenland. This model has a native horizontal resolution of 55 km. In comparison to five existing Greenland geothermal heat flow models, our model has the lowest mean geothermal heat flow for Greenland onshore areas (44 mW m-2). Our model's most distinctive spatial feature is pronounced low geothermal heat flow (< 40 mW m-2) across the North Atlantic Craton of southern Greenland. Crucially, our model does not show an area of elevated heat flow that might be interpreted as remnant from the Icelandic Plume track. Finally, we discuss the substantial influence of paleoclimatic and other corrections on geothermal heat flow measurements in Greenland. The in-situ measurement database and gridded heat flow model, as well as other supporting materials, are freely available from the GEUS DataVerse (https://doi.org/10.22008/FK2/F9P03L; Colgan and Wansing, 2021). [ABSTRACT FROM AUTHOR]

A geohazard assessment workflow is presented that maximizes the use of 3D seismic reflection data to improve the safety and success of offshore scientific drilling. This workflow has been implemented for International Ocean Discovery Program (IODP) Proposal 909 that aims to core seven sites with targets between 300 and 1000 m below seabed across the north-western Greenland continental shelf. This glaciated margin is a frontier petroleum province containing potential drilling hazards that must be avoided during drilling. Modern seismic interpretation techniques are used to identify, map and spatially analyse seismic features that may represent subsurface drilling hazards, such as seabed structures, faults, fluids and challenging lithologies. These hazards are compared against the spatial distribution of stratigraphic targets to guide site selection and minimize risk. The 3D seismic geohazard assessment specifically advanced the proposal by providing a more detailed and spatially extensive understanding of hazard distribution that was used to confidently select eight new site locations, abandon four others and fine-tune sites originally selected using 2D seismic data. Had several of the more challenging areas targeted by this proposal only been covered by 2D seismic data, it is likely that they would have been abandoned, restricting access to stratigraphic targets. The results informed the targeted location of an ultra-high-resolution 2D seismic survey by minimizing acquisition in unnecessary areas, saving valuable resources. With future IODP missions targeting similarly challenging frontier environments where 3D seismic data are available, this workflow provides a template for geohazard assessments that will enhance the success of future scientific drilling. [ABSTRACT FROM AUTHOR]

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 structures, 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 successions including contourite drifts and glacial related shelf progradation towards the west and south-west. [ABSTRACT FROM AUTHOR]

The article discusses a study which examined the geological development and hydrocarbon potential of the Baffin Bay region in Greenland. Topics covered include the use of the Schlumberger Petrel software in the interpretation of seismic horizons and units, the recovery of marine mudstone deposits with source-rock intervals and oil seeps and the amplitude anomalies identified from the interpretation of seismic facies and attributes.

Terrestrial records from the Canadian Arctic Archipelago indicate that a temperate and moist climate prevailed during the Pliocene, i.e., before the intensification of Northern Hemisphere glaciations, but the controlling factors causing these conditions remains elusive. Here we present marine seismic reflection evidence of contiguous kilometer-scale sedimentary drifts, or contourites, buried below the West Greenland shelf, which relates high-latitude Pliocene warmth to intense geostrophic currents along the eastern Baffin Bay margin. Seismic to borehole correlation indicates that enhanced current-induced deposition began during the middle Miocene, ca. 17-15 Ma, and terminated during the late Pliocene onset of global cooling. The transition from along-slope sediment transport to trough-mouth fan progradation designates the onset of Greenland Ice Sheet glaciers advancing across the continental shelf and coincides with increasing iceberg productivity in Baffin Bay and the Nordic Seas from 3.3 to 2.7 Ma. Our results suggest that the Baffin Bay-West Greenland margin formed a late Neogene passageway for persistent ocean boundary currents, and we infer that the Pliocene high-latitude warmth was to a significant extent caused or enhanced by advection of subtropical heat and moisture to the Arctic regions. Attenuation of the poleward heat flux conveyed by the paleo-current system may have been critical for allowing glacial buildup in the Canadian Arctic and northern Greenland during the late Pliocene. We further surmise that vertical tectonic adjustments of the continental margin played a role in this attenuation, which eventually caused the demise of meridional ocean circulation through Baffin Bay. [ABSTRACT FROM AUTHOR]

Abstract: Subsurface mapping in the northeastern part of Baffin Bay, offshore Northwest Greenland indicates the presence of large basement structures and sedimentary basins. We identify eight seismic-stratigraphic units that can be genetically related to the regional geology and tectonic development. The seismic interpretation includes the top of Paleocene to Eocene volcanic rocks, which cover most parts of the southern and western study area. Using this horizon as a time marker, the seismic units are divided into pre-Cenozoic and Palaeogene to Neogene strata based on comparison to equivalent units exposed onshore West Greenland and Canada and sampled by exploration wells farther south in the Disko West/offshore Nuuk region. Our interpretation of the faults and tectonic elements suggest that the main extensional faults and basin formation took place mainly during the Cretaceous and into the Paleocene. Subsequent compressional tectonics and inversion were accompanied by strike-slip faulting and local transtensional faults and flexures. This last phase of deformation corresponds to the well documented Eurekan Orogeny in Ellesmere Island and northern Greenland that developed as a result of northward motion and possible counterclockwise rotation of Greenland relative to the North American plate. We surmise that these tectonic phases exerted a strong control on basin infill by activation of hinterland sediment sources during Cretaceous and Palaeogene times. The deep basins may include Cretaceous and Palaeogene organic-rich sediments with hydrocarbon source potential. We estimate that maturation could have started during the Eocene. [Copyright &y& Elsevier]

The groundwork for the northeast Atlantic opening was laid during the latest Jurassic to mid-Cenozoic. The period is well-investigated on the Norwegian and UK continental margins at which the tremendous petroleum potential to a large extent resulted from the latest Jurassic to mid-Cenozoic development. Harsh ice conditions have made investigations of the NE Greenlandic margin more difficult. Based on a large 2D seismic dataset tied to cored stratigraphic boreholes, three phases of rifting leading to continental breakup are documented: 1) latest Jurassic to mid-Cretaceous, 2) mid-Cretaceous to Maastrichtian and 3) Maastrichtian to early Eocene. This development is in many ways comparable to offshore Norway. However, Early Cretaceous rifting was more severe offshore NE Greenland compared to elsewhere in the northeastern Atlantic with more than 10 km downfaulting and accumulation of up to 16 km of Lower Cretaceous strata in the Danmarkshavn and Thetis basins. During the mid-Cretaceous, rifting ceased in most of the Danmarkshavn Basin and the inner Thetis Basin but continued in the outer Thetis Basin. This coincides with a shift in rifting taking place in the Barents Sea, offshore central Norway, and onshore NE Greenland. During the latest Cretaceous, rifting shifted seawards to the outermost NE Greenland margin and the eventual line of continental break-up, again mirroring the development at the central Norwegian margin. Coincident uplift of Greenland resulted in clinoform progradation across the central and southern Danmarkshavn Basin and incursion of Greenland-derived sand to offshore central Norway. The uplift and change in rifting may reflect the initial effects of the Icelandic mantle plume building up underneath Greenland. Shortly thereafter, magmatism commenced along parts of the NE Greenland margin followed by continental break-up. Subsequently, small amounts of compression on the outer margin formed subtle folds and small thrusts during presumably Oligocene to early Miocene times. • Seismic investigations of the NE Greenland margin tied with boreholes. • E Cretaceous, L Cretaceous and Maastrichtian–Eocene rift phases shaped NE Greenland. • Tremendous basins and intra-basin highs formed during the rifting. • The three rift phases recur across other northern N Atlantic margins. • The northern N Atlantic E. Cretaceous rift center was located offshore NE Greenland. [ABSTRACT FROM AUTHOR]

Mantle convection is a fundamental process that shapes the Earth's surface by providing the driving and resisting forces for horizontal motion of tectonic plates, as well as for inducing non-isostatic vertical motion commonly termed "dynamic topography". Growing observational constraints of past plate motion and dynamic topography have led to better understanding of the history of surface expression induced by mantle flow. Often these two surface motion signals are studied separately. However, the existence of a thin, mechanically weak asthenosphere allows geodynamicists to link horizontal and vertical motion changes together via mantle flow properties in the context of pressure-driven Poiseuille-type flow. In this paper, we utilize publicly available geologic and geophysical datasets to study early Paleogene plate kinematics and spatiotemporal evolution of dynamic topography in the North Atlantic region. We find that the North America (NAM) and Greenland (GRN) plates experienced a rapid kinematic change around late Paleocene–early Eocene, coinciding with episodes of surface uplift inferred from stage-resolution stratigraphic information around the North Atlantic, Labrador Sea and Baffin Bay. We quantitatively tie these surface motion signals together to underlying asthenospheric flow processes by estimating torque variations on NAM and GRN. These are parameterized in terms of reconstructed kinematic changes as well as predicted Poiseuille-type flow induced by increasing Icelandic plume flux and speedup of Farallon slab. Our analysis indicates (1) that the torque-change associated with the Icelandic plume flux closely resembles the ones inferred from kinematic reconstructions, and (2) that the inclusion of slab effects does not modify significantly such a scenario. Our findings shed light on the role of asthenospheric channelized flow generated by the Icelandic plume in influencing the early Paleogene North Atlantic surface dynamics. • The North American and Greenland plates experienced a speedup in the early Paleogene. • This speedup correlates with inferred uplifts of the North Atlantic region. • Torque analysis shows that the Icelandic plume drives both surface motion changes. [ABSTRACT FROM AUTHOR]

We present new and reprocessed seismic reflection data from the area where the southeast and southwest Greenland margins intersected to form a triple junction south of Greenland in the early Tertiary. During breakup at 56 Ma, thick igneous crust was accreted along the entire 1300-km-long southeast Greenland margin from the Greenland Iceland Ridge to, and possibly ∼100 km beyond, the triple junction into the Labrador Sea. However, highly extended and thin crust 250 km to the west of the triple junction suggests that magmatically starved crustal formation occurred on the southwest Greenland margin at the same time. Thus, a transition from a volcanic to a non-volcanic margin over only 100–200 km is observed. Magmatism related to the impact of the Iceland plume below the North Atlantic around 61 Ma is known from central-west and southeast Greenland. The new seismic data also suggest the presence of a small volcanic plateau of similar age close to the triple junction. The extent of initial plume-related volcanism inferred from these observations is explained by a model of lateral flow of plume material that is guided by relief at the base of the lithosphere. Plume mantle is channelled to great distances provided that significant melting does not take place. Melting causes cooling and dehydration of the plume mantle. The associated viscosity increase acts against lateral flow and restricts plume material to its point of entry into an actively spreading rift. We further suggest that thick Archaean lithosphere blocked direct flow of plume material into the magma-starved southwest Greenland margin while the plume was free to flow into the central west and east Greenland margins. The model is consistent with a plume layer that is only moderately hotter, ∼100–200°C, than ambient mantle temperature, and has a thickness comparable to lithospheric thickness variations, ∼50–100 km. Lithospheric architecture, the timing of continental rifting and viscosity changes due to melting of the plume material are therefore critical parameters for understanding the distribution of magmatism. [Copyright &y& Elsevier]

Abstract: We have developed a generic dynamic model of extension of the lithosphere, which predicts major element composition and volume of melt generated from initial extension to steady state seafloor spreading. Stokes equations for non-Newtonian flow are solved and the mantle melts by decompression. Strengthening of the mantle due to dehydration as melting progresses is included. The composition is then empirically related to depletion. Using a crystallisation algorithm, the predicted primary melt composition was compared with mean North Atlantic mid-ocean ridge basalt (MORB). At steady state, using half spreading rates from 10 to 20 mm yr−1 and mantle potential temperatures of 1300 to 1325 °C we predict a major element composition that is within the variation in the mean of North Atlantic MORB. This model is applied to the Southeast Greenland margin, which has extensive coverage of seismic and ODP core data. These data have been interpreted to indicate an initial pulse of magmatism on rifting that rapidly decayed to leave oceanic crustal thickness of 8 to 11 km. This pattern of melt production can be recreated by introducing an initial hot layer of asthenosphere beneath the continental lithosphere and by having a period of fast spreading during early opening. The hot layer was convected through the melt region giving a pulse of high magnesian and low silica melt during the early rifting process. The predicted major element composition of primary melts generated are in close agreement with primary melts from the Southeast Greenland margin. The observed variations in major element composition are reproduced without a mantle source composition anomaly. [Copyright &y& Elsevier]

The potential sea-level equivalent of the Greenland Ice Sheet (~7 m) has led to an ever-increasing interest in how the ice sheet has responded to warmer temperatures in the geological past. This has resulted in contrasting models where Greenland is thought to have been both nearly ice-free and persistently ice-covered. This contradiction is due to a lack of long-term geological or ice core records that go significantly beyond the last glacial cycle. Much of the Greenland margin is composed of thick sedimentary successions, including km-thick glaciogenic wedges. In this work, we first used a grid of high-quality 2D seismic reflection data offshore northwest Greenland to develop a large-scale model for the glaciogenic evolution of the Melville Bugt and Upernavik Trough Mouth Fans (TMF). This is constrained by a simple age model and provides insight into a major glacial outlet from the northwestern Greenland Ice Sheet over the last 2.7 million years. A number of progradational units are separated by onlapping surfaces that record eleven major cycles of ice sheet advance to the (palaeo-) shelf edge and subsequent retreat. The large-scale sedimentary architecture indicates that prior to the Middle Pleistocene Transition (MPT) deposition was evenly distributed along strike. After this, during the MPT, the depositional pattern was replaced by focusing and separation into two individual ice stream flows through the two contemporary cross-shelf troughs. This likely indicates a change in ice sheet geometry and dynamics through the MPT. In the second part of this study we investigated 3D seismic reflection data from the Melville Bugt TMF that capture ice sheet history through and after the MPT. Seismic geomorphological analysis provided further support for the transition to focused ice stream flow with the observation of five sets of buried mega-scale glacial lineations (MSGL). These landforms are indicative of ice streaming and demonstrate marine-based glaciation, palaeo-ice flow, and sediment transport pathways prior to the last glacial cycle. The age model suggests that the MSGL were formed during several glacial stages since the onset of the MPT. These observations provide the first 3D evidence for ice stream landforms anywhere along the Greenland continental margin prior to the Last Glacial Maximum. Such records supplement limited proxy data and are essential for constraining the spatio-temporal configuration and longevity of the Greenland Ice Sheet. [ABSTRACT FROM AUTHOR]