Geology topics
Research about Russia, United States
Source-linked reports with geographic coverage including Russia, United States.
Distribution of trace elements in bottom sediment of the northern Bering Sea
2-dimensional contour and 3-dimensional value-surface maps of semi-quantitative emission spectographic analyses for over 50 elements in surface sediment from 180 sampling stations are presented. For purposes of discussion, certain of these elements have been grouped into the following categories: petroleum indicators, heavy metals, potentially toxic elements, chemically sensitive elements, major elements, minor elements, and a group of elements of economic interest.
Marine seismic sonobuoy data from the Bering Sea region
Throughout the field seasons of 1975 to 1978, the Geological Survey carried out an extensive program of seismic sonobuoy research aboard the R/V S.P. LEE over the entire Bering Sea region. 75 successful sonobuoy refraction and wide angle reflection stations were recorded over the shelf areas of Navarin Basin, St. George Basin and Umnak Plateau, and the deep ocean areas of Bowers Basin and the Aleutian Basin. Of these, 18 were in shallow water depths (less than 200 meters), 21 were in intermediate depths (200 to 3000 meters) and 36 were in deep water (greater than 3000 meters). The shortest of the sonobuoy lines is 3 nautical miles (5.6 km) while the longest is almost 42 n.m. (78 km). The average distance 1s 17 n.m. (21 km). These unreversed sonobuoy lines were all recorded with a tuned air gun array and were all shot along single channel, and often multichannel, seismic lines.
Structure and sediment distribution in the western Bering Sea
Eleven seismic reflection profiles across Shirshov Ridge and the adjacent deep-water sedimentary basins (Komandorsky and Aleutian Basins) are presented to illustrate the sediment distribution in the western Bering Sea. A prominent seismic reflecting horizon, Reflector P (Middle—Late Miocene in age), is observed throughout both the Aleutian and Komandorsky Basins at an approximate subbottom depth of 1 km. This reflector is also present, in places, on the flanks and along the crest of Shirshov Ridge. The thickness of sediments beneath Reflector P is significantly different within the two abyssal basins. In the Aleutian Basin, the total subbottom depth to acoustic basement (basalt?) is about 4 km, while in the Komandorsky Basin the depth is about 2 km. Shirshov Ridge, a Cenozoic volcanic feature that separates the Aleutian and Komandorsky Basins, is an asymmetric bathymetric ridge characterized by thick sediments along its eastern flank and steep scarps on its western side. The southern portion of the ridge has more structural relief that includes several deep, sediment-filled basins along its summit. Velocity data from sonobuoy measurements indicate that acoustic basement in the Komandorsky Basin has an average compressional wave velocity of 5.90 km/sec. This value is considerably larger than the velocities measured for acoustic basement in the northwestern Aleutian Basin (about 5.00 km/sec) and in the central Aleutian Basin (5.40–5.57 km/sec). In the northwestern Aleutian Basin, the low-velocity acoustic basement may be volcaniclastic sediments or other indurated sediments that are overlying true basaltic basement. A refracting horizon with similar velocities (4.6–5.0 km/sec) as acoustic basement dips steeply beneath the Siberian continental margin, reaching a maximum subbottom depth of about 8 km. The thick welt of sediment at the base of the Siberian margin may be the result of sediment loading or tectonic depression prior to Late Cenozoic time.
Preliminary residual magnetic map of the Bering Sea Basin and the Kamchatka Peninsula
No abstract available.
Aleutian-Bering Sea region seismic reflection profiles
No abstract available.
Quaternary correlations across Bering Strait
Recent Soviet and American studies cast new light on the history of the Bering land bridge.
Cenozoic history of the Bering land bridge
The seaway between the Pacific and Arctic basins has often been a land route between Siberia and Alaska.
Some effects of recent volcanic ash falls, with especial reference to Alaska
No abstract available.