Commander Basin
Encyclopedia
The Commander Basin is located between the Shirshov Ridge
and the Kamchatka Peninsula
. Its southern boundary is the Aleutian arc (see figure) and occupies the western part of the Bering Sea
. The Kamchatka Strait
provides a deep water access to the basin from the southwest.
The basins sedimentary cover is less than 2 km thick. In the southwestern portion of the basin near the Ulakahn Fault, linear magnetic anomalies associated with the Early Miocene
have been identified. The magnetic anomalies support a sequential opening of the Commander Basin resulting from stresses on the interface between the Eurasian and Pacific plates. The structures of the Bering Sea floor at the Commander Basin were created 17 to 21 Million years before the present.
The Commander Basin floor is a horizontal plain 3800–3900 m deep. It is covered with 2000–6000 m of sediment overlying an oceanic crust which is 12–14 km thick. Active spreading in the Commander Basin occurred between 40 and 10 Myr ago, with subduction of the basin floor along the Ulakhan fault underneath the Kamchatka peninsula. There are four major fracture zones in the basin and magnetic lineations have been detected in the basin. Except in the southern end of the basin, the spreading center has been subducted.
The water in the basin circulates in a cyclonic gyre
, with the western Kamchatka Current flowing southward along the Kamchatka Peninsula. The northward leg of the gyre is outside of the Commander Basin, and is carried by the Bering Slope Current, which flows along the edge of the continental shelf at the eastern edge of the Aleutian Basin
. To the south, the Commander Basin connects to the North Pacific through the 4.4 km wide, 4,420 meter deep Kamchatka Strait and the 2.0 km wide, 2,000 meter deep Near Strait.
Shirshov Ridge
The Shirshov Ridge is located on the eastern border of the Commander Basin below the Kamchatka Peninsula. It extends directly southward for a distance of 750 km toward the Aleutian arc in the eastern part of the Bering Sea ....
and the Kamchatka Peninsula
Kamchatka Peninsula
The Kamchatka Peninsula is a peninsula in the Russian Far East, with an area of . It lies between the Pacific Ocean to the east and the Sea of Okhotsk to the west...
. Its southern boundary is the Aleutian arc (see figure) and occupies the western part of the Bering Sea
Bering Sea
The Bering Sea is a marginal sea of the Pacific Ocean. It comprises a deep water basin, which then rises through a narrow slope into the shallower water above the continental shelves....
. The Kamchatka Strait
Kamchatka Strait
Kamchatka Strait is a 191 km-wide strait in Russia. It separates Bering Island of the Commander Islands from the mainland , and connects the Bering Sea in the north with the Pacific Ocean in the south....
provides a deep water access to the basin from the southwest.
The basins sedimentary cover is less than 2 km thick. In the southwestern portion of the basin near the Ulakahn Fault, linear magnetic anomalies associated with the Early Miocene
Early Miocene
The Early Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Aquitanian and Burdigalian stages....
have been identified. The magnetic anomalies support a sequential opening of the Commander Basin resulting from stresses on the interface between the Eurasian and Pacific plates. The structures of the Bering Sea floor at the Commander Basin were created 17 to 21 Million years before the present.
The Commander Basin floor is a horizontal plain 3800–3900 m deep. It is covered with 2000–6000 m of sediment overlying an oceanic crust which is 12–14 km thick. Active spreading in the Commander Basin occurred between 40 and 10 Myr ago, with subduction of the basin floor along the Ulakhan fault underneath the Kamchatka peninsula. There are four major fracture zones in the basin and magnetic lineations have been detected in the basin. Except in the southern end of the basin, the spreading center has been subducted.
The water in the basin circulates in a cyclonic gyre
Gyre
A gyre in oceanography is any large system of rotating ocean currents, particularly those involved with large wind movements. Gyres are caused by the Coriolis Effect; planetary vorticity along with horizontal and vertical friction, which determine the circulation patterns from the wind curl...
, with the western Kamchatka Current flowing southward along the Kamchatka Peninsula. The northward leg of the gyre is outside of the Commander Basin, and is carried by the Bering Slope Current, which flows along the edge of the continental shelf at the eastern edge of the Aleutian Basin
Aleutian Basin
The Aleutian Basin is an oceanic basin under the southwestern Bering Sea. While the northeastern half of the Bering Sea overlies the North American Plate in relatively shallow water, the Aleutian Basin consists of oceanic plate—the remnant of the Kula Plate that was mostly subducted under...
. To the south, the Commander Basin connects to the North Pacific through the 4.4 km wide, 4,420 meter deep Kamchatka Strait and the 2.0 km wide, 2,000 meter deep Near Strait.