Bransfield Strait

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Bransfield Strait
Location of Bransfield Strait in Antarctica
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Bransfield Strait
The strait from Livingston Island, with Antarctic Peninsula seen on the horizon Bransfield-Strait.jpg
The strait from Livingston Island, with Antarctic Peninsula seen on the horizon

Bransfield Strait or Fleet Sea (Spanish : Estrecho de Bransfield, Mar de la Flota) is a body of water about 100 kilometres (60 mi) wide extending for 300 miles (500 km) in a general northeast – southwest direction between the South Shetland Islands and the Antarctic Peninsula.

Contents

History

The strait was named in about 1825 by James Weddell, Master, Royal Navy, for Edward Bransfield, Master, RN, who charted the South Shetland Islands in 1820. It is called Mar de la Flota by Argentina. On 23 November 2007, the MS Explorer struck an iceberg and sank in the strait; all 154 passengers were rescued and no injuries were reported.

Description

The undersea trough through the strait is known as Bransfield Trough ( 61°30′S54°0′W / 61.500°S 54.000°W / -61.500; -54.000 ). The basin is about 400 km long and 2 km deep, between the South Shetland Island Arc and the Antarctic Peninsula. It was formed by rifting behind the islands, which began about 4 million years ago. [1] Ongoing rifting has caused recent earthquakes and volcanism. The Strait hosts a chain of submerged seamounts of volcanic origin, including the presently inactive Orca Seamount. [2] However last volcanic activity at Orca Seamount is judged to have occurred in the recent past as there are temperature anomalies in the seawater around at the seamount. [3] Thermophilic and hyperthermophilic microorganisms organism have been found at the seamount. [3] Thermophiles found on the seafloor outside Orca Seamount may indicate that thermal waters of Orca Seamount may travel laterally through geological structures or that currents bring in thermal water from Deception Island, an active volcano. [3]

Antarctic Specially Protected Area

Blackfin Icefish Chaenocephalus aceratus.jpg
Blackfin Icefish

An area of relatively shallow marine waters of about 1021 km2, off the western and southern coasts of Low Island, has been designated an Antarctic Specially Protected Area (ASPA 152) because it is one of only two known sites near the United States’s Palmer Station suitable for bottom trawling for fish and other benthic organisms. Fish have been collected from the site by scientists from Palmer Station since the early 1970s, and it is recognised as an important spawning ground for several species, including Black Rockcod and Blackfin Icefish. [4]

See also

Related Research Articles

Geography of Antarctica Geographic features of Antarctica

The geography of Antarctica is dominated by its south polar location and, thus, by ice. The Antarctic continent, located in the Earth's southern hemisphere, is centered asymmetrically around the South Pole and largely south of the Antarctic Circle. It is washed by the Southern Ocean or, depending on definition, the southern Pacific, Atlantic, and Indian Oceans. It has an area of more than 14 million km2.

Deception Island Active volcanic island in the South Shetland archipelago

Deception Island is an island in the South Shetland Islands close to the Antarctic Peninsula with a large and safe natural harbour. This island is the caldera of an active volcano, which seriously damaged local scientific stations in 1967 and 1969. The island previously held a whaling station; it is now a tourist destination and scientific outpost, with Argentine and Spanish research bases. While various countries have asserted sovereignty, it is still administered under the Antarctic Treaty System.

Antarctic Peninsula Peninsula located in northern Antarctica

The Antarctic Peninsula, known as O'Higgins Land in Chile and Tierra de San Martin in Argentina, and originally as the Palmer Peninsula in the US and Graham Land in the United Kingdom, is the northernmost part of the mainland of Antarctica.

South Shetland Islands A group of islands north of the Antarctic Peninsula

The South Shetland Islands are a group of Antarctic islands with a total area of 3,687 km2 (1,424 sq mi). They lie about 120 km (75 mi) north of the Antarctic Peninsula, and between 430 km (270 mi) to 900 km (560 mi) southwest from the nearest point of the South Orkney Islands. By the Antarctic Treaty of 1959, the islands' sovereignty is neither recognized nor disputed by the signatories and they are free for use by any signatory for non-military purposes.

Bridgeman Island (South Shetland Islands)

Bridgeman Island or Bridgemans's Island or Bridgman Island or Helena Island is one of the South Shetland Islands. It is an almost circular, volcanic island marked by steep sides, 0.8 kilometres (0.5 mi) long and 240 m (787 ft) high, lying 37 kilometres (23 mi) east of King George Island. Bridgeman Island is located at 62°04′S56°44′W and has an elevation of 240 m (787 ft). Bridgeman Island is an established name dating back to about 1820. Bridgeman Island is the remnants of a much larger volcanic edifice that is now largely submerged. The eroded volcano does not display youthful volcanic features. Several reports of 19th-century fumarolic activity may instead refer to the much younger Penguin Island.

Penguin Island (South Shetland Islands)

Penguin Island is one of the smaller of the South Shetland Islands of Antarctica.

Burgas Peninsula

Burgas Peninsula is a predominantly ice-covered peninsula forming the east extremity of Livingston Island in the South Shetland Islands, Antarctica extending 10 km in the east-northeast direction towards Renier Point and 4.7 km wide. It is bounded by Bruix Cove, Moon Bay and Mugla Passage to the north, and Bransfield Strait to the south-southeast. The peninsula's interior is occupied by the Delchev Ridge of Tangra Mountains.

Strandzha Glacier

Strandzha Glacier is located on Burgas Peninsula, eastern Livingston Island in the South Shetland Islands, Antarctica northeast of Ropotamo Glacier, south of Sopot Ice Piedmont and southwest of Pautalia Glacier. It is bounded by Delchev Peak to the west, Spartacus Peak, Trigrad Gap and Yavorov Peak to the northwest, and by Elena Peak to the north, extends 1.6 km in northeast-southwest direction and 800 m in northwest-southeast direction, and flows southeastward into Bransfield Strait.

Start Point (Livingston Island)

Start Point is a point marking the northwest end of Byers Peninsula, Livingston Island in the South Shetland Islands, Antarctica and forming the southwest side of the entrance to Svishtov Cove and the northeast side of the entrance to the New Plymouth bay. Discovered by Edward Bransfield in January 1820, and so named by him because of its resemblance to a point on the south coast of England by the same name and because it was the place where his operations began.

Cape Shirreff

Cape Shirreff is a prominent cape at the north end of the rocky peninsula which separates Hero Bay and Barclay Bay on the north coast of Livingston Island, in the South Shetland Islands of Antarctica. The cape was named by Edward Bransfield in 1820 after Captain William H. Shirreff, the British commanding officer in the Pacific at that time.

Astrolabe Island

Astrolabe Island, located at 63°17′S58°40′W, is an island 5 km (3 mi) long, lying in the Bransfield Strait 23 km (14 mi) northwest of Cape Ducorps, Trinity Peninsula in Antarctica. It was discovered by the French expedition, 1837–40, under Captain Jules Dumont d'Urville, and named by him for his chief expedition ship, the Astrolabe. The island was photographed from the air and triangulated by FIDASE, 1956–57.

Hurd Peninsula

Hurd Peninsula lies between South Bay and False Bay on the south coast of Livingston Island in the South Shetland Islands, Antarctica. The Spanish Juan Carlos I Antarctic Base and the Bulgarian St. Kliment Ohridski Base are situated on its west coast.

San Telmo Island

San Telmo Island is an island forming the west side of Shirreff Cove on the north-west coast of Ioannes Paulus II Peninsula, Livingston Island in the South Shetland Islands of Antarctica. It has a surface area of 22 hectares.

Shetland Plate Tectonic microplate off the tip of the Antarctic Peninsula

The Shetland Plate, or South Shetland Plate, is a tectonic microplate located off the tip of the Antarctic Peninsula and contains the South Shetland Islands. The plate is bordered on three sides by the Antarctic Plate and the fourth side is bordered by the Scotia Plate. The northwestern border is defined by the South Shetland Trench separating the Shetland Plate to the south from the Antarctic Plate to the north. This trench is the remnant of a subduction zone where the defunct Phoenix Plate, now part of the Antarctic Plate, subducted under the Antarctic Peninsula and the Shetland Islands. The southeastern border is rift zone with the Antarctic Plate creating the Bransfield Basin. The southwestern and northeastern boundaries are each part of larger fracture zones. The southwestern border is the Hero Fracture Zone and separates the Antarctic Plate to the southwest from the Shetland Plate to the northeast. The northeastern boundary is the Shackleton Fracture Zone and separates the Shetland Plate to the southwest from the Scotia Plate.

Orca Seamount Underwater volcano near King George Island in Antarctica, in the Bransfield Strait.

Orca Seamount is a seamount near King George Island in Antarctica, in the Bransfield Strait. While it is inactive, last volcanic activity at Orca Seamount is judged to have occurred in the recent past as there are temperature anomalies in the seawater around at the seamount. Thermophilic and hyperthermophilic microorganisms organism have been found at the seamount.

Coppermine Peninsula

Coppermine Peninsula is the 1.7 km long, 500 m wide and rising to 105 m rugged rocky promontory forming the northwest extremity of Alfatar Peninsula and Robert Island in the South Shetland Islands, Antarctica and lying between English Strait to the west and Carlota Cove to the east. It is linked to Alfatar Peninsula to the southeast by a narrow isthmus bounded by Carlota Cove to the north and the 1 km wide and 460 m indenting Coppermine Cove to the south. The feature is named in association with the adjacent Coppermine Cove, a descriptive name given by sealers in about 1821 from the copper-coloured staining of the lavas and tuffs in the area.

Risopatrón Base Antarctic base

Risopatrón Base, also Luis Risopatrón Base, is a small Chilean Antarctic research base in the northwest of Robert Island in the South Shetland Islands, Antarctica situated on the isthmus linking Coppermine Peninsula to Alfatar Peninsula and bounded by Carlota Cove to the north and Coppermine Cove to the south. Established as a refuge in 1949 and opened as a base in 1954, the facility supports summer research in geology, geophysics and terrestrial biology.

The Antarctic Peninsula, roughly 1,000 kilometres (650 mi) south of South America, is the northernmost portion of the continent of Antarctica. Like the associated Andes, the Antarctic Peninsula is an excellent example of ocean-continent collision resulting in subduction. The peninsula has experienced continuous subduction for over 200 million years, but changes in continental configurations during the amalgamation and breakup of continents have changed the orientation of the peninsula itself, as well as the underlying volcanic rocks associated with the subduction zone.

Wordie Seamount A seamount in Bransfield Strait, Antarctica

Wordie Seamount is a seamount located in Bransfield Strait, Antarctica. The feature is named after James Wordie, geologist on Ernest Shackleton's 1914 expedition to Antarctica.

Bransfield Basin

The Bransfield Basin is a back-arc rift basin located off the Northern tip of the Antarctic Peninsula. The basin lies within a Northeast and Southwest trending strait that separates the peninsula from the nearby South Shetland Islands to the Northwest. The basin extends for more than 500 kilometres from Smith Island to a portion of the Hero Fracture Zone. The basin can be subdivided into three basins: Western, Central, and Eastern. The Western basin is 130 kilometres long by 70 kilometres wide with a depth of 1.3 kilometres, the Central basin is 230 kilometres long by 60 kilometres wide with a depth of 1.9 kilometres, and the Eastern basin is 150 kilometres long by 40 kilometres wide with a depth of over 2.7 kilometres. The three basins are separated by the Deception Island and Bridgeman Island. The moho depth in the region has been seismically interpreted to be roughly 34 kilometres deep.

References

  1. Yi, S.; Batten, D. J.; Lee, S. J. (2005). "Provenance of recycled palynomorph assemblages recovered from surficial glaciomarine sediments in Bransfield Strait, offshore Antarctic Peninsula". Cretaceous Research. 26: 906–919. doi:10.1016/j.cretres.2005.06.004.
  2. Hatzky, Jörn (2005): The Orca Seamount Region, Antarctica (Sect. 5.5.2). In: Peter C. Wille (ed.), Sound Images of the Ocean in Research and Monitoring, Springer-Verlag Berlin.
  3. 1 2 3 Rodrigo, Cristian; Blamey, Jenny M.; Huhn, Oliver; Provost, Christine (2018). "Is there an active hydrothermal flux from the orca seamount in the Bransfield Strait, antarctica?". Andean Geology . 45 (3): 344. doi: 10.5027/andgeov45n3-3086 .
  4. "Western Bransfield Strait" (PDF). Management Plan for Antarctic Specially Protected Area No. 149: Measure 10, Annex. Antarctic Treaty Secretariat. 2009. Retrieved 2013-10-02.

Coordinates: 63°S59°W / 63°S 59°W / -63; -59