Abstract A number of rock samples were collected from two dredge positions on the Lomonosov Ridge at water depths of 2–3.5 km. The dredge samples are dominated by sediments deformed and metamorphosed under greenschist-facies conditions 470 myr ago according to 40 Ar/ 39 Ar dating of metamorphic muscovite. This shows that the Lomonosov Ridge was involved in a major Mid-Ordovician orogenic event that correlates with early arc–terrane accretion observed in northern Ellesmere Island, Svalbard, and other parts of the Caledonian belt. Detrital zircon age spectra of these metasediments span the Mesoproterozoic–Palaeoproterozoic with a main peak at around 1.6 Ga, and a pattern similar to that known from Caledonian metasedimentary rocks in East Greenland and northern Norway, as well as from Cambrian sediments in Estonia and Palaeozoic sediments on Novaya Zemlya. A second population of dredge samples comprises undeformed, non-metamorphic sandstones and siltstones. Detrital zircons in these sediments span the Palaeoproterozoic with a few Archaean zircons. Both rock types are covered by an up to 8 Ma ferromanganese crust and are evaluated to represent outcrop, and apatite fission-track data from three of the rock samples indicate that exposure at the seabed corresponds to a regional event of uplift and erosion that affected the Arctic in the Late Miocene. The data from the Lomonosov Ridge suggest that the 470 Ma orogenic event extended from Scotland and northern Scandinavia into the Arctic, including Svalbard, the Pearya Terrane and the Chukchi Borderlands. Supplementary material: Detrital zircon age data and details of the thermal history constraints are available at: https://doi.org/10.6084/m9.figshare.c.3852151

Abstract In many areas of the Arctic, sedimentary sequences have been exhumed from significantly greater depths during the Cenozoic, with 2 km of section or more removed in some areas. Implications for exploration include enhanced maturity levels, possible loss of reservoired hydrocarbons as a result of seal breach, and phase changes due to pressure reduction. While the importance of Cenozoic exhumation to hydrocarbon prospectivity in individual basins is widely recognized, less well recognized is the regional synchroneity in the main phases of Cenozoic exhumation over wide areas of the Arctic and North Atlantic. Thermal history reconstruction studies in the Barents Sea and the Alaskan North Slope, based on application of apatite fission track analysis and vitrinite reflectance, reveal three main episodes of exhumation, in Paleocene, Eocene–Oligocene and Miocene times, and correlative exhumation episodes have been identified in a number of published studies in these and other areas. Previous attempts to explain these episodes of exhumation have been focussed on local mechanisms. However, our results reveal a pattern of regionally synchronous exhumation over a wide region, not only of the Arctic but also in many areas around the European North Atlantic margin, suggesting that events in each area are a regional response to events at plate boundaries, perhaps coupled to imbalances of crustal forces at continental boundaries. To date, no convincing mechanism has been put forward for producing such regional exhumation episodes, despite the fact that in many areas they exert critical control on regional hydrocarbon prospectivity. We suggest that serious attention should be directed to investigating the underlying mechanisms.

Abstract We present observations that demonstrate that the elevated passive margins around the North Atlantic were formed by episodic, post-rift uplift movements that are manifest in the high-lying peneplains that characterize the coastal mountains, in the unconformities in the adjacent sedimentary basins and in accelerated subsidence in the basin centres. Results from West Greenland show that subsidence of the rifted margin took place for c . 25 Myr after rifting and breakup in the Paleocene, as predicted by classical rift theory, but that this development was reversed by a series of uplift movements (starting at c . 35, 10 and 5 Ma) that remain unexplained. East Greenland and Scandinavia seem to have had a similar evolution of post-rift subsidence followed by uplift starting at c . 35 Ma. There was no notable fall in sea-level at this time, so the subsiding basins must have been inverted by tectonic forces. We speculate that the forces causing this phase were related to the plate boundary reorganization in the North Atlantic around Chron 13 time. One feature that these areas have in common is that uplift took place along the edges of cratons where the thickness of the crust and lithosphere changes substantially over a short distance. It may be that the lateral contrasts in the properties of the stretched and unstretched lithosphere make the margins of the cratons unstable long after rifting. These vertical movements have profound influence on hydrocarbon systems, not only in frontier areas such as West and East Greenland, where Mesozoic basins are deeply truncated and exposed onshore, but also for the understanding of near-shore hydrocarbon deposits in mature areas such as the North Sea Basin, where low-angular unconformities may represent episodes of deposition and removal of significant sedimentary sections.

Abstract This paper summarizes new and recent apatite fission track analysis and vitrinite reflectance results from across the Irish Sea basin system and its margins, which provide new constraints on the magnitude and timing of post-Palaeozoic exhumation across this area. In particular, these results suggest that this region has experienced a complex, multi-phase exhumation history. Distinct episodes of kilometre-scale exhumation occurred during the early Cretaceous, early Palaeogene and late Palaeogene-Neogene times, with the overall magnitude of exhumation in each episode decreasing over time. Regional early Cretaceous exhumation removed up to 3 km of section from the Irish Sea basins, and appears to be related to incipient Atlantic rifting. Early Palaeogene exhumation attained up to 2 km and was driven by a combination of localized tectonic inversion and regional epeirogenic uplift, although early Palaeogene palaeotemperatures within parts of the Irish Sea basin system are dominated by non-burial-related processes. A final phase of exhumation, related to late Palaeogene-Neogene tectonic inversion, uniformly removed c . 1 km of section from this region. Given that these exhumation episodes coincide temporally with important periods of deformation at pre-existing or incipient plate boundaries, events at plate margins are interpreted to have exerted the primary control on the Mesozoic–Cenozoic exhumation of the Irish Sea basin system.