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Research about Beaufort Sea

Source-linked reports with geographic coverage including Beaufort Sea.

52 records · Page 3Linked to original sources
USGS1994

Polar bear maternity denning in the Beaufort Sea

The distribution of polar bears ( Ursus maritimus ) is circumpolar in the Northern Hemisphere, but known locations of maternal dens are concentrated in relatively few, widely scattered locations. Denning is either uncommon or unknown within gaps. To understand effects of industrial development and propose increases in hunting, the temporal and spatial distribution of denning in the Beaufort Sea must be known. We caputred and radiocollared polar bears between 1981 and 1991 and determined tht denning in the Beaufort Sea region was sufficient to account for the estimated population there. Of 90 dens, 48 were on drifting pack ice, 38 on land, and 4 on land-fast ice. The portions of dens on land was higher ( P = 0.029) in later compared with earlier years of the study. Bears denning on pack ice drifting as far as 997 km ( x = 385 km) while in dens. there was no difference in cub production by bears denning on land and pack ice ( P = 0.66). Mean entry and exit dates were 11 November and 5 April for land dens and 22 November and 26 March for pack-ice dens. Female polar bears captured in the Beaufort Sea appeared to be isolated from those caught east of Cape Bathurst in Canada. Of 35 polar bears that denned along the mainland coast of Alaska and Canada 80% denned between 137°00′W and 146°59′W . Bears followed to >1 den did not reuse sites and consecutive dens were 20-1,304 km apart. However radio-collared bears are largely faithful to substrate (pack-ice, land, and land-fast ice) and the general geographic area of previous dens. Bears denning on land may be vunerable to human activities such as hunting and industrial development. However, predictable denning chronology and lack of site fidelity indicate that many potential impacts on denning polar bears could be mitigated.

Alaska↗
USGS1987

Summer spawning in the fourhorn sculpin, Myoxocephalus quadricornis, from Alaska

Histological ovarian analysis indicates summer spawning occurs in Myoxocephalus quadricornis (Fourhorn Sculpin) from Alaska. Previous studies have shown this species spawns during winter in the Baltic Sea; the data presented herein suggests that geographical variation may occur in the timing of spawning of this species.

Alaska↗
USGS1981

Ice-gouge data, Beaufort Sea, Alaska, 1972-1980

The interaction of sea ice with the sea floor is an important factor affecting geologic processes on high latitude shelves. One of the most obvious forms of this interaction is the formation of furrow-like gouges or the sea floor. These gouges are caused by wind- and current-driven ice masses that rake the seabed with their keels. Since the advent of side-scanning sonar about 1970, the morphology and character of these seabed features have been under study. Ice gouges have been reported from the Bering Sea (Thor and Nelson, 1980); from the Chukchi Sea (Rex, 1955; Toimil, 1978); from the Beaufort Sea off Alaska (Brooks, 1974; Carsola, 1954; Reimnitz et al., 1972); from the Beaufort Sea off Canada (Kindle, 1924; Lewis, 1978; Pelletier and Shearer, 1972; Wahlgren, 1979); from the east coast of Canada (Harris, 1974); from the northeast Atlantic (Belderson et al., 1973); and from the Great Lakes (Berkson and Clay, 1973).

Alaska↗
USGS1979

CDP seismic sections of the western Beaufort continental margin

The continental rise, slope, and shelf in the Beaufort Sea off northern Alaska were surveyed with 5600 km of common-depth-point (CDP) seismic data by the U.S. Geological Survey in 1977. The lower continental rise consists of a wedge of at least 4.5 km of low-velocity, generally flat-lying, parallel-bedded sediments. Slump-related diapiric folds, probably cored by shale, occur on the upper rise and lower slope. The observed minimum depth to oceanic basement in the Canada Basin requires an age for this basin of at least 120 m.y., assuming it to be floored by oceanic crust with a subsidence history similar to that of the Atlantic and Pacific oceans.

Alaska↗
USGS1978

Stamukhi shoals of the Arctic - some observations from the Beaufort Sea

A number of linear shoals, representing pronounced topographic anomalies on the surface of the Arctic shelf, have been studied in the Prudhoe Bay area. These shoals have been referred to in several previous studies. Based on seismic reflection records, Reimnitz et al., (1972a), stated that the shoals are constructional features younger than the post-Wisconsin transgression. Large chunks of grounded ice have frequently been seen on the linear shoals of the inner shelf. These ice chunks form barriers parallel to the shore (Reimnitz, et al. 1972b). Reimnitz and Barnes (1974) considered the lack of gravel concentrations on the shoals to be evidence that the stream of pack ice drifting past northern Alaska carries very little gravel today. Lewellen (1977) referred to the linear shoals as submerged barrier islands, while Reimnitz, et al., (1977b) pointed out that, although similar in shape to barrier islands, the linear shoals are very different in composition and do not appear to represent drowned harrier islands. They show that the shoals localize the formation of major shear and pressure events in the ice, which in turn cause the formation of linear belts of deformed and grounded ice. Today the shoals appear to be migrating under the influence of ice-bottom interaction, and indeed may have formed in response to ice-bottom interaction within the "stamukhi zone". The shoals migrate rather slowly and retain their shapes over periods of 25 years, yet control the location and stabilize the outer edge of the floating fast ice zone, and provide shelter for the inner shelf and coast. Reimnitz et al. (1977b) surmised that similar artificial structures might be used to modify the ice environment on the arctic shelf.

Alaska↗
USGS1976

Summary report of the sediments, structural framework, petroleum potential, environmental conditions, and operational considerations of the United States Beaufort Sea, Alaska area

Proposed OCS Oil and Gas Lease Sale i54comprising approximately 20,000 sq km in the Beaufort Sea of northern Alaska, has good potential for petroleum in each of the three geologic provinces it contains. However, only about half of the proposed area underlies waters shallower than 20 m, the apparent present technologic limit for petroleum development in polar seas impacted by a drifting permanent ice pack.

Alaska↗
USGS1975

Surface current observations--Beaufort Sea, 1972

Sediment transport via water and ice in the Beaufort Sea off northern Alaska is related to the movement of the surficial waters. As development proceeds along the north slope of alaska, a knowledge of the potential drift trajectories of water, ice, sediment and pollutants will be needed. In an attempt to better define the probable paths and rates of transport, 4200 surface drift cards were dropped during the U.S. Coast Guard WEBSEC cruise of August and September, 1972. The results of this release are the subject of this report. Because the data presented here will be used primarily by those interested in solving problems of transport, the emphasis has been placed on data presentation rather than a detailed analysis of the circulation. (Sinha-OEIS)

Alaska↗
USGS1975

Heavy-mineral trends in the Beaufort Sea

Sediments of the Beaufort Sea, off the North Slope of Alaska contain a great variety of heavy minerals. These include garnet, chrome spinel, augite, pigeonite, diopside, hornblende, enstatite, hypersthene, epidote, clinozoisite, zoisite, apatite, tourmaline, chloritoid, sphene, zircon, and opaque minerals. Much rarer constituents are glaucophane, lamprobolite, rutile, kyanite, staurolite, and riebeckite. The heavy-mineral fractions that were not treated with hydrochloric acid contain "iron-stained aggregates", grains of unidentifiable material encrusted with limonite. Samples containing relatively high percentages of iron-stained aggregates and altered opaque minerals occur in depths less than 10 m and within 16 km from shore. Garnet increases in abundance from east to west, which corresponds to a similar increase in garnet abundance in coastal outcrops of the Gubik Formation sands. Only garnet and iron-stained aggregates appear to have source-related distribution patterns. The other heavy minerals lack distinct distributive provinces, reflecting an environment dominated by intense mixing by ice-gouging and bioturbation and a homogenous source area. Waves and currents are not strong enough to sort sediments at depths greater than 10 m except during summer storms. The source of the Beaufort Sea heavy minerals is dominated by contributions from the Alaskan North Slope deposits of Tertiary and younger age. The Colville River, largest in the region, is probably the most influential in transporting sediments, but because of wave and current—mixing of sediments on the shelf, exact contributions from each river drainage cannot be ascertained. Coastal erosion of the Gubik Formation is probably at least as important as the Colville River in supplying heavy minerals to the Beaufort Sea.

Alaska↗