Abstract Nine main petroleum provinces containing recoverable resources totalling 61 Bbbl liquids+269 Bbbloe of gas are known in the Arctic. The three best known major provinces are: West Siberia–South Kara, Arctic Alaska and Timan–Pechora. They have been sourced principally from, respectively, Upper Jurassic, Triassic and Devonian marine source rocks and their hydrocarbons are reservoired principally in Cretaceous sandstones, Triassic sandstones and Palaeozoic carbonates. The remaining six provinces except for the Upper Cretaceous–Palaeogene petroleum system in the Mackenzie Delta have predominantly Mesozoic sources and Jurassic reservoirs. There are discoveries in 15% of the total area of sedimentary basins ( c. 8×10 6 km 2 ), dry wells in 10% of the area, seismic but no wells in 50% and no seismic in 25%. The United States Geological Survey estimate yet-to-find resources to total 90 Bbbl liquids+279 Bbbloe gas, with four regions – South Kara Sea, Alaska, East Barents Sea, East Greenland – dominating. Russian estimates of South Kara Sea and East Barents Sea are equally positive. The large potential reflects primarily the large undrilled areas, thick basins and widespread source rocks.

Abstract A total of 143 sedimentary successions that contain, or may be prospective for, hydrocarbons were identified in the Arctic Region north of 58–64°N and mapped in four quadrants at a scale of 1:11 000 000. Eighteen of these successions (12.6%) occur in the Arctic Ocean Basin, 25 (17.5%) in the passive and sheared continental margins of the Arctic Basin and 100 (70.0%) on the Circum-Arctic continents of which one (<1%) lies in the active margin of the Pacific Rim. Each succession was assigned to one of 13 tectono-stratigraphic and morphologic classes and coloured accordingly on the map. The thickness of each succession and that of any underlying sedimentary section down to economic basement, where known, are shown on the map by isopachs. Major structural or tectonic features associated with the creation of the successions, or with the enhancement or degradation of their hydrocarbon potential, are also shown. Forty-four (30.8%) of the successions are known to contain hydrocarbon accumulations, 64 (44.8%) are sufficiently thick to have generated hydrocarbons and 35 (24.5%) may be too thin to be prospective.

Abstract New Circum-Arctic maps of magnetic and gravity anomalies have been produced by merging regional gridded data. Satellite magnetic and gravity data were used for quality control of the long wavelengths of the new compilations. The new Circum-Arctic digital compilations of magnetic, gravity and some of their derivatives have been analyzed together with other freely available regional and global data and models in order to provide a consistent view of the tectonically complex Arctic basins and surrounding continents. Sharp, linear contrasts between deeply buried basement blocks with different magnetic properties and densities that can be identified on these maps can be used, together with other geological and geophysical information, to refine the tectonic boundaries of the Arctic domain.

Abstract We identify and discuss 57 magnetic anomaly pattern domains spanning the Circum-Arctic. The domains are based on analysis of a new Circum-Arctic data compilation. The magnetic anomaly patterns can be broadly related to general geodynamic classification of the crust into stable, deformed (magnetic and nonmagnetic), deep magnetic high, oceanic and large igneous province domains. We compare the magnetic domains with topography/bathymetry, regional geology, regional free air gravity anomalies and estimates of the relative magnetic ‘thickness’ of the crust. Most of the domains and their geodynamic classification assignments are consistent with their topographic/bathymetric and geological expression. A few of the domains are potentially controversial. For example, the extent of the Iceland Faroe large igneous province as identified by magnetic anomalies may disagree with other definitions for this feature. Also the lack of definitive magnetic expression of oceanic crust in Baffin Bay, the Norwegian–Greenland Sea and the Amerasian Basin is at odds with some previous interpretations. The magnetic domains and their boundaries provide clues for tectonic models and boundaries within this poorly understood portion of the globe.

Abstract The Palaeozoic motion of the future Arctic continents is presented in the animation found in the accompanying CD-ROM. The animation shows snapshots of the motion of the tectonic blocks from 550 to 250 Ma in 3 million year steps. The locations of the blocks are controlled mainly by palaeomagnetic pole values for the blocks tied to known geological events, particularly the three main Arctic orogenies: the Scandian Caledonian which began in the Silurian, the Ellesmerian in the Late Devonian and the Uralian that began in the Late Pennsylvanian. Perhaps the most significant observation to come out of the animation is that the future Arctic continents were never very far from one another during the Palaeozoic. The maximum distance from Baltica to Laurentia may have reached 6000 km during the Middle Cambrian but the Arctic continents all surrounded the same eastern Iapetus Ocean and, by Silurian, they were quite close. Reliance on the ‘Y-loop’ palaeomagnetic data causes extremely rapid motion of Gondwana during the Silurian. Consequently the ‘X-path’ for that period is used. The palaeomagnetic poles for 422 and 406 Ma have been eliminated so that Gondwana motion is within the bounds of present day plate motion. Supplementary material: A Quicktime™ movie of palaeogeographic and tectonic evolution of the Arctic region during the Palaeozoic is available at http://www.geolsoc.org.uk/SUP18472 .

Abstract Sixty-three maps illustrate geodynamic evolution and development of palaeoenvironments and palaeolithofacies of the Circum-Arctic region during Phanerozoic times. After the break-up of Rodinia and Pannotia in the Early Palaeozoic, the major Arctic plates Baltica, Siberia and Laurentia drifted from their original position around the South Pole towards the Supercontinent Pangea, which existed in the equatorial position during Late Palaeozoic and Early Mesozoic times. During the Mesozoic and Cenozoic plates gathered around newly formed Arctic Ocean. Large continental masses were assembled from major plates and numerous small plates and terranes on the northern hemisphere and around the North Pole. All the continents were by now connected. Carbonates were abundant in Siberia and Laurentia during Palaeozoic times. Clastic sedimentation prevailed during Mesozoic and Cenozoic times. The distribution of lithofacies shows climatic change associated with continental assembly and disassembly as well as with the steady northward drift of the continents.

Abstract Over the past 75 years, hydrocarbon exploration of Arctic regions north of the Arctic Circle (66°N) has yielded some 450 discoveries which collectively account for 2.5% of global conventional liquids discovered to date and 15.5% of the world's discovered conventional natural gas. Accumulations occur in rocks ranging from Cambrian to Pleistocene in age but 94% of all Arctic hydrocarbon resources occur in clastic reservoirs of Mesozoic age. Although discoveries have been reported from 15 different basins onshore and offshore Alaska, Canada, Norway and Russia, 75% of all discovered resources are located in the portion of Russia's Western Siberia Basin that lies north of 66°N. Hydrocarbon accumulations discovered in the Arctic region have been generated from nearly 40 different petroleum systems. The main elements of these petroleum systems such as sources, reservoirs and seals are described and the chronology of these depositional events is summarized in two chronologic charts representing the Eastern and Western hemispheres.

Abstract The USGS has assessed undiscovered petroleum resources in the Arctic through geological mapping, basin analysis and quantitative assessment. The new map compilation provided the base from which geologists subdivided the Arctic for burial history modelling and quantitative assessment. The CARA was a probabilistic, geologically based study that used existing USGS methodology, modified somewhat for the circumstances of the Arctic. The assessment relied heavily on analogue modelling, with numerical input as lognormal distributions of sizes and numbers of undiscovered accumulations. Probabilistic results for individual assessment units were statistically aggregated taking geological dependencies into account. Fourteen papers in this Geological Society volume present summaries of various aspects of the CARA.

Abstract The US Geological Survey recently assessed the potential for undiscovered conventional petroleum in the Arctic. Using a new map compilation of sedimentary elements, the area north of the Arctic Circle was subdivided into 70 assessment units, 48 of which were quantitatively assessed. The Circum-Arctic Resource Appraisal (CARA) was a geologically based, probabilistic study that relied mainly on burial history analysis and analogue modelling to estimate sizes and numbers of undiscovered oil and gas accumulations. The results of the CARA suggest the Arctic is gas-prone with an estimated 770–2990 trillion cubic feet of undiscovered conventional natural gas, most of which is in Russian territory. On an energy-equivalent basis, the quantity of natural gas is more than three times the quantity of oil and the largest undiscovered gas field is expected to be about 10 times the size of the largest undiscovered oil field. In addition to gas, the gas accumulations may contain an estimated 39 billion barrels of liquids. The South Kara Sea is the most prospective gas assessment unit, but giant gas fields containing more than 6 trillion cubic feet of recoverable gas are possible at a 50% chance in 10 assessment units. Sixty per cent of the estimated undiscovered oil resource is in just six assessment units, of which the Alaska Platform, with 31% of the resource, is the most prospective. Overall, the Arctic is estimated to contain between 44 and 157 billion barrels of recoverable oil. Billion barrel oil fields are possible at a 50% chance in seven assessment units. Undiscovered oil resources could be significant to the Arctic nations, but are probably not sufficient to shift the world oil balance away from the Middle East.

Abstract Palaeogeographic and tectono-stratigraphic considerations in the greater Barents Sea show that the distribution of reservoirs and hydrocarbon source rocks from the Late Palaeozoic to the Palaeogene can be related to three tectonic phases. Firstly, the Palaeozoic Caledonain Orogeny caused uplift to the west, followed by eastward sediment distribution across the shelf, towards carbonate platforms to the east. Secondly the Late Palaeozoic–Mesozoic Uralide Orogeny induced uplift to the east, causing widespread clastic deposition and reversal of the sediment distribution pattern. Thirdly, major Late Mesozoic–Cenozoic rifting and crustal breakup in the western Barents Sea led to the current basin configuration. Reservoir rocks comprise Late Palaeozoic carbonates and spiculites, Mesozoic terrestrial and marine sandstones and Palaeogene deep-water sandstones. Hydrocarbon source rocks range in age from Silurian to Early Cretaceous, and are grouped into three petroleum systems derived from Late Palaeozoic, Triassic and Late Jurassic source rocks. Multiple tectonic episodes caused formation of a variety of trap types, of which extensional fault blocks and gently folded domes have been the most prospective. Volumetric considerations of generated petroleum indicate that charging is not a limiting factor, except in the western margin.

Abstract New gravity and magnetic anomaly maps for the Barents and Kara Sea region only allow mapping of tectonic features where the thick sedimentary cover is tectonically disturbed. Maps of sedimentary thickness and depth to top basement and the Moho differ between the western and eastern Barents Sea, although detailed thickness and depth estimates require calibration by seismic data. Internal plate boundaries created during the amalgamation of the Barents Sea region were not detected using potential field data.

Abstract In 1995–2006 FSUE ‘Sevmorgeo’ within the framework of the Federal Program of state survey baselines network development performed geophysical works in the Barents and Kara seas along four regional profiles: 1-AR (Kola Peninsula–Heysa Island of Franz-Joseph Land Archipelago); 2-AR (Central part of the Barents region–Novaya Zemlya – Yamal Peninsula); 3-AR (White Sea–Severnaya Zemlya Archipelago); and 4-AR (Taimyr Peninsula–Franz-Joseph Land Archipelago). Geophysical surveys included works using seismic refraction–deep seismic sounding technique, seismic reflection–common-depth point technique, seismic acoustic profiling and gravimetric and magnetic measurements. Integrated geophysical surveys along the regional profiles enabled more exact definition of the Earth deep crustal structure and the sedimentary cover of the main tectonic elements.

Abstract In the Palaeozoic history of the Timan–Pechora sedimentary basin three stages of organic structures are identified: Caradocian–Early Emsian, Middle Frasnian–Tournaisian and Late Visean–Early Permian. The distribution and dimensions of the various organogenic buildups in the Timan–Pechora basin show that Palaeozoic reef formation was regulated by the skeletal reef biota, by the physical and chemical parameters controlling the porostromate calcimicrobes and microbial carbonates, by global eustatic fluctuations of sea-level, and by the tectonic evolution of the Pechora Plate and the Palaeo-Urals Ocean. The development of petroleum systems in the Timan–Pechora Basin is largely controlled by primary (organic substance, its composition, quantity and maturity, continuous sinking of the basin's sedimentary cover) and secondary (stagnation period of sedimentation and the newest tectonic movements) factors. An integrated approach using the geochemical data enabled us to build a reliable model of petroleum genesis for the Timan–Pechora Basin with high probability of evaluating the petroleum potential and the composition of hydrocarbon systems.

Abstract In the northern part of the Varandey–Adzva zone carbonate reservoirs have developed that have porosity favourable for oil and gas accumulations. The void space in these reservoirs, besides primary porosity, is associated with fracturing, giving rise to good reservoir potential in both the onshore and offshore parts of the Varandey–Adzva zone. The similarity of today's structure and the development during the main stages of geological history for offshore and onshore parts, the availability in the section of productive oil- and gas-bearing reservoirs, the high capacity of the reservoirs, the uniformity of lithofacial composition of the productive intervals and the uniqueness of the deposits structure – all these features contribute to the oil and gas potential of the Pechora Sea structures. Supplementary material: Supplementary Tables 14.1–14.7 are available at http://www.geolsoc.org.uk/SUP18473 .