Geology topics

Research about Arctic Circle

Source-linked reports with geographic coverage including Arctic Circle.

6 recordsLinked to original sources

USGS2017

The 2008 Circum-Arctic Resource Appraisal

Professional Paper 1824 comprises 30 chapters by various U.S. Geological Survey authors, including introduction and methodology chapters, which together provide documentation of the geological basis and methodology of the 2008 Circum-Arctic Resource Appraisal, results of which were first released in August 2008. Twenty-eight chapters summarize the petroleum geology and resource potential of individual, geologically defined provinces north of the Arctic Circle, including those of northern Alaska, northern Canada, east and west Greenland, and most of Arctic Russia, as well as certain offshore areas of the north Atlantic Basin and the Polar Sea. Appendixes tabulate the input and output information used during the assessment.

Professional Paper↗

USGS2017

Introduction to the 2008 Circum-Arctic Resource Appraisal (CARA) professional paper

The amount of yet-to-find oil and gas in the high northern latitudes is one of the great uncertainties of future energy supply. The possibility of extensive new petroleum developments in the Arctic Ocean is of interest to the Arctic nations, to petroleum companies, and to those concerned with the delicate and changing Arctic environment. The U.S. Geological Survey (USGS) 2008 Circum-Arctic Resource Appraisal (CARA) had the express purpose of conducting a geologically based assessment of undiscovered petroleum north of the Arctic Circle, thereby providing an initial evaluation of resource potential.

Professional Paper↗

USGS2017

Methodology for assessment of undiscovered oil and gas resources for the 2008 Circum-Arctic Resource Appraisal

The methodological procedures used in the geologic assessments of the 2008 Circum-Arctic Resource Appraisal (CARA) were based largely on the methodology developed for the 2000 U.S. Geological Survey World Petroleum Assessment. The main variables were probability distributions for numbers and sizes of undiscovered accumulations with an associated risk of occurrence. The CARA methodology expanded on the previous methodology in providing additional tools and procedures more applicable to the many Arctic basins that have little or no exploration history. Most importantly, geologic analogs from a database constructed for this study were used in many of the assessments to constrain numbers and sizes of undiscovered oil and gas accumulations.

Professional Paper↗

USGS2015

A simplified, data-constrained approach to estimate the permafrost carbon–climate feedback

We present an approach to estimate the feedback from large-scale thawing of permafrost soils using a simplified, data-constrained model that combines three elements: soil carbon (C) maps and profiles to identify the distribution and type of C in permafrost soils; incubation experiments to quantify the rates of C lost after thaw; and models of soil thermal dynamics in response to climate warming. We call the approach the Permafrost Carbon Network Incubation–Panarctic Thermal scaling approach (PInc-PanTher). The approach assumes that C stocks do not decompose at all when frozen, but once thawed follow set decomposition trajectories as a function of soil temperature. The trajectories are determined according to a three-pool decomposition model fitted to incubation data using parameters specific to soil horizon types. We calculate litterfall C inputs required to maintain steady-state C balance for the current climate, and hold those inputs constant. Soil temperatures are taken from the soil thermal modules of ecosystem model simulations forced by a common set of future climate change anomalies under two warming scenarios over the period 2010 to 2100. Under a medium warming scenario (RCP4.5), the approach projects permafrost soil C losses of 12.2–33.4 Pg C; under a high warming scenario (RCP8.5), the approach projects C losses of 27.9–112.6 Pg C. Projected C losses are roughly linearly proportional to global temperature changes across the two scenarios. These results indicate a global sensitivity of frozen soil C to climate change ( γ sensitivity) of −14 to −19 Pg C °C −1 on a 100 year time scale. For CH 4 emissions, our approach assumes a fixed saturated area and that increases in CH 4 emissions are related to increased heterotrophic respiration in anoxic soil, yielding CH 4 emission increases of 7% and 35% for the RCP4.5 and RCP8.5 scenarios, respectively, which add an additional greenhouse gas forcing of approximately 10–18%. The simplified approach presented here neglects many important processes that may amplify or mitigate C release from permafrost soils, but serves as a data-constrained estimate on the forced, large-scale permafrost C response to warming.

Philosophical Transactions of the Royal Society A:↗

USGS2010

Aggregation methodology for the circum-arctic resource appraisal

This paper presents a methodology that intends to aggregate the results of a recent assessment of undiscovered conventional oil and gas resources of the Arctic by the U.S. Geological Survey. The assessment occurred in 48 geologically defined regions called assessment units. The methodology includes using assessor specified pair-wise correlations as the basis to construct a correlation matrix. Sampling from this matrix generates more realistic uncertainty estimates of aggregated resources than if assumptions of total independence or total dependence are made. The latter two assumptions result in overly narrow or overly broad estimates. Aggregation results for resources in regions north of the Arctic Circle are presented.

Mathematical Geosciences↗

USGS1966

Magnetic data on the structure of the central Arctic Region

A study of 23,000 miles of total intensity aeromagnetic profiles in the central Arctic has been made by the U. S. Geological Survey and the U. S. Coast and Geodetic Survey. The profiles were flown at 20,000 feet above sea level and cover approximately 1,350,000 square miles of the Arctic Ocean between the North Pole and the North American continent. When the profiles are smoothed to remove crustal anomalies, the resulting contoured values differ from the U. S. Hydrographic Office Chart 1703 N for 1955 corrected to 1951 by as much as 2000 gammas in the northern part of the Arctic Archipelago. A nondipole regional focus east of Greenland has decreased in amplitude but has changed very little in position since 1907.5. There is a profound difference in the magnetic characteristics of the rocks on either side of the underwater Lomonosov Ridge across the Arctic Ocean. In the Eurasian Basin the high-altitude profiles are relatively smooth or show only minor anomalies, but on the North American side of the ridge there is a large area of closely spaced, high-amplitude anomalies which has been designated the Central Magnetic Zone. Although the anomaly trends parallel the Alpha Rise, this zone is far more extensive, including nearly half of the Canadian Basin on one side and probably all the Central Arctic Basin on the other side of the rise. The Lomonosov Ridge is marked by a persistent anomaly of moderate size that indicates the presence of magnetic material in the ridge. Probable block-fault structures along the flanks of the Alpha Rise are associated with blocklike magnetic anomalies of comparable widths. A characteristic magnetic pattern occurs over an area of jagged bottom topography in the Eurasian Basin. A similar magnetic pattern over part of the Lena Trough may indicate another area of jagged topography. The belt of epicenters associated with the Mid-Atlantic Ridge continues through this rugged part of the Eurasian Basin, but the absence of the typical high magnetic anomaly makes it doubtful that the mid-oceanic ridge extends through this part of the Arctic . Magnetic data indicate that the thick sections of sedimentary rocks in the Paleozoic geosynclinal belts of northern Ellesmere Island and northern Greenland continue out under the adjacent continental shelves north of Greenland, west of the Arctic Archipelago, north of the part of Alaska east of Barrow, and under part of the Chukchi Shelf, and that they make up the bulk of the Nansen Swell off Spitsbergen. Thick sedimentary fill is indicated in the magnetically flat areas of the Eurasian Basin next to the Lomonosov Ridge and in the southern part of the Canadian Basin. The magnetic profiles on the Eurasian side of the Lomonosov Ridge closely resemble typical magnetic profiles over both Atlantic and Pacific oceans, where as the profiles of the Central Magnetic Zone on the North American side of the Lomonosov Ridge are completely unlike the oceanic data and show a striking similarity to typical profiles over the Precambrian rocks of the Canadian Shield and its buried equivalent under the Central Stable Region of the United States. Therefore, it is concluded that the Arctic region consists of a probable oceanic area on the Eurasian side and a basin formed by downdropped continental rocks, presumably a Precambrian complex similar to that of the Canadian Shield, on the North American side of the ridge.

Geological Society of America Bulletin↗