Charlie-Gibbs Fracture Zone

Charlie-Gibbs Fracture Zone is a system of two parallel fracture zones. It is the most prominent interruption of the Mid-Atlantic Ridge between the Azores and Iceland. It can be traced over more than 2000 kilometers, all the way from north-east of Newfoundland to south-west of Ireland. It took 90 million years for the fault to grow to this length.

Coordinates: 52°30′N 31°45′W / 52.50°N 31.75°W

Charlie-gibbs-full-extent
Charlie-Gibbs Fracture Zone, full extent
Charliegibbsschema-en
Schematic overview of Charlie-Gibbs Fracture Zone
Charliegibbstransform
Charlie-Gibbs transform fault

Structure

The transform fault of the southern fracture zone displaces the Mid-Atlantic Ridge, coming from the Azores Triple Junction, to the west over a distance of 120 km. At longitude 31.75W a south to north seismically active rift valley with a length of 40 km connects the western end of the southern transform to the eastern end of the northern transform.[1] The northern transform fault displaces the spreading ridge over another 230 km to the west before it connects to the northern part of the Mid-Atlantic Ridge going to Iceland. Thus the total offset of the system is 350 kilometers.

Both transform faults continue eastward and westward as inactive fracture zones.

Exploration

In 1963 the existence of a transform fault near latitude 53N was first postulated on the basis of earthquake epicenter data by Bruce Heezen and Maurice Ewing.[2] Also the study of ocean currents indicated that there should be a deep passage through the Mid-Atlantic Ridge. In 1966 the area was investigated by USCGC Spar (WLB-403) on its return from an Arctic survey.[3] The fault was named Charlie Fracture Zone after the USCG Ocean Weather Station Charlie at 52°45′N 35°30′W / 52.750°N 35.500°W, athwart the fault. In July 1968 USNS Josiah Willard Gibbs (T-AGOR-1) conducted a more extended survey.[4] It was proposed that the fracture zone be renamed Gibbs Fracture Zone, as fracture zones are generally named for research vessels. The proposal was accepted only in part, and currently the official name is Charlie-Gibbs Fracture Zone.[5] Note that the double name refers to the two parallel fracture zones together. The individual fracture zones have to be referred to as Charlie-Gibbs North and South.

Seamounts

The transform area contains two named seamounts:

Protected area

The Charlie-Gibbs Marine Protected Area is a conservation area in the Charlie-Gibbs fracture zone in North Atlantic international waters.[8][9]

References

  1. ^ Lilwall, R. C.; Kirk, R. E. (1985). "Ocean-bottom seismograph observations on the Charlie-Gibbs fracture zone". Geophysical Journal International. 80: 195. Bibcode:1985GeoJI..80..195L. doi:10.1111/j.1365-246X.1985.tb05085.x.
  2. ^ Leonard Johnson, G. (1967). "North atlantic fracture zones near 53°". Earth and Planetary Science Letters. 2 (5): 445–448. Bibcode:1967E&PSL...2..445J. doi:10.1016/0012-821X(67)90187-2.
  3. ^ Report on voyage of USCGC Spar
  4. ^ Fleming, H. S.; Cherkis, N. Z.; Heirtzler, J. R. (1970). "The Gibbs Fracture Zone: A double fracture zone at 52°30'N in the Atlantic Ocean". Marine Geophysical Researches. 1: 37. doi:10.1007/BF00310008.
  5. ^ a b "IHO-IOC GEBCO Gazetteer of Undersea Feature Names, March 2011 version; www.gebco.net". GEBCO. Archived from the original on 2012-04-21. Retrieved 2011-11-16.
  6. ^ Minia-homepage Gebco gives years 1885-1907, which would be incompatible with the Titanic (1912).
  7. ^ atlantic-cable.com
  8. ^ http://www.charlie-gibbs.org/charlie/node/14
  9. ^ Proforma for compiling the characteristics of a potential MPA Archived January 12, 2014, at the Wayback Machine

External links

Atlantic meridional overturning circulation

The Atlantic meridional overturning circulation (AMOC) is the zonally-integrated component of surface and deep currents in the Atlantic Ocean. It is characterized by a northward flow of warm, salty water in the upper layers of the Atlantic, and a southward flow of colder, deep waters that are part of the thermohaline circulation. These "limbs" are linked by regions of overturning in the Nordic and Labrador Seas and the Southern Ocean. The AMOC is an important component of the Earth’s climate system, and is a result of both atmospheric and thermohaline drivers.

David McNiven Garner

David McNiven Garner (26 November 1928 – 13 May 2016) was notable as a published research physicist, with a focus in physical oceanography and ocean circulation.

Fracture zone

A fracture zone is a linear oceanic feature—often hundreds, even thousands of kilometers long—resulting from the action of offset mid-ocean ridge axis segments. They are a consequence of plate tectonics. Lithospheric plates on either side of an active transform fault move in opposite directions; here, strike-slip activity occurs. Fracture zones extend past the transform faults, away from the ridge axis; seismically inactive (because both plate segments are moving in the same direction), they display evidence of past transform fault activity, primarily in the different ages of the crust on opposite sides of the zone.

In actual usage, many transform faults aligned with fracture zones are often loosely referred to as "fracture zones" although technically, they are not.

Hope Spots

Hope Spots are ecologically unique areas of the ocean designated for protection under a global conservation campaign overseen by Mission Blue, a non-profit organization founded by Sylvia Earle with her 2009 TED prize wish.Hope Spots can be Marine Protected Areas (MPA) that need attention or new sites. They are chosen for their contributions to biodiversity, the carbon sink, and important habitat. Hope Spot status is intended to alleviate the pressures human resource extraction places on the ocean by making the site higher priority to become an MPA, where resource extraction, like fishing and drilling, may be forbidden under law.There are 76 Hope Spots worldwide (as of September 9, 2016). An additional 22 nominations for Hope Spots are currently under consideration and three nominations have been deferred.At the time of Earle's wish, less than 1% of the ocean was protected. Earle advocated for the creation of a system of parks like the national park system in the United States. The goal of the Hope Spot campaign is raise public support, gain the attention of leaders and policy makers, and ultimately create enough Hope Spots to protect 20% of the ocean by 2020.

Iron fertilization

Iron fertilization is the intentional introduction of iron to iron-poor areas of the ocean surface to stimulate phytoplankton production. This is intended to enhance biological productivity and/or accelerate carbon dioxide (CO2) sequestration from the atmosphere.

Iron is a trace element necessary for photosynthesis in plants. It is highly insoluble in sea water and in a variety of locations is the limiting nutrient for phytoplankton growth. Large algal blooms can be created by supplying iron to iron-deficient ocean waters. These blooms can nourish other organisms.

Multiple ocean labs, scientists and businesses have explored fertilization. Beginning in 1993, thirteen research teams completed ocean trials demonstrating that phytoplankton blooms can be stimulated by iron augmentation. Controversy remains over the effectiveness of atmospheric CO2 sequestration and ecological effects. The most recent open ocean trials of ocean iron fertilization were in 2009 (January to March) in the South Atlantic by project Lohafex, and in July 2012 in the North Pacific off the coast of British Columbia, Canada, by the Haida Salmon Restoration Corporation (HSRC).Fertilization occurs naturally when upwellings bring nutrient-rich water to the surface, as occurs when ocean currents meet an ocean bank or a sea mount. This form of fertilization produces the world's largest marine habitats. Fertilization can also occur when weather carries wind blown dust long distances over the ocean, or iron-rich minerals are carried into the ocean by glaciers, rivers and icebergs.

North Atlantic Deep Water

North Atlantic Deep Water (NADW) is a deep water mass formed in the North Atlantic Ocean. Thermohaline circulation (properly described as meridional overturning circulation) of the world's oceans involves the flow of warm surface waters from the southern hemisphere into the North Atlantic. Water flowing northward becomes modified through evaporation and mixing with other water masses, leading to increased salinity. When this water reaches the North Atlantic it cools and sinks through convection, due to its decreased temperature and increased salinity resulting in increased density. NADW is the outflow of this thick deep layer, which can be detected by its high salinity, high oxygen content, nutrient minima, high 14C/12C, and chlorofluorocarbons (CFCs).CFCs are anthropogenic substances that enter the surface of the ocean from gas exchange with the atmosphere. This distinct composition allows its path to be traced as it mixes with Circumpolar Deep Water (CDW), which in turn fills the deep Indian Ocean and part of the South Pacific. NADW and its formation is essential to the Atlantic Meridional Overturning Circulation (AMOC), which is responsible for transporting large amounts of water, heat, salt, carbon, nutrients and other substances from the Tropical Atlantic to the Mid and High Latitude Atlantic.In the conveyor belt model of thermohaline circulation of the world's oceans, the sinking of NADW pulls the waters of the North Atlantic drift northward. However, this is almost certainly an oversimplification of the actual relationship between NADW formation and the strength of the Gulf Stream/North Atlantic drift.NADW has a temperature of 2-4 °C with a salinity of 34.9-35.0 psu found at a depth between 1500 and 4000m.

Outline of oceanography

The following outline is provided as an overview of and introduction to Oceanography.

Sei whale

The sei whale ( or ) (Balaenoptera borealis) is a baleen whale, the third-largest rorqual after the blue whale and the fin whale. It inhabits most oceans and adjoining seas, and prefers deep offshore waters. It avoids polar and tropical waters and semienclosed bodies of water. The sei whale migrates annually from cool and subpolar waters in summer to winter in temperate and subtropical waters, with a lifespan of 70 years.Reaching 19.5 m (64 ft) long and weighing as much as 28 t (28 long tons; 31 short tons), the sei whale consumes an average of 900 kg (2,000 lb) of food every day; its diet consists primarily of copepods, krill, and other zooplankton. It is among the fastest of all cetaceans, and can reach speeds of up to 50 km/h (31 mph) (27 knots) over short distances. The whale's name comes from the Norwegian word for pollock, a fish that appears off the coast of Norway at the same time of the year as the sei whale.Following large-scale commercial whaling during the late 19th and 20th centuries, when over 255,000 whales were killed, the sei whale is now internationally protected, although limited hunting occurs under a controversial research program conducted by Japan. As of 2008, its worldwide population was about 80,000, less than a third of its prewhaling population.

USS San Carlos (AVP-51)

USS San Carlos (AVP-51) was a Barnegat-class seaplane tender built for the United States Navy during World War II. San Carlos, named after San Carlos Bay, Florida, was in commissioned from 1944 to 1947 and earned three battle stars for service in the Pacific during World War II. After eleven years in reserve, San Carlos was converted to oceanographic research ship USNS Josiah Willard Gibbs (T-AGOR-1)—named after American scientist Josiah Willard Gibbs—and placed in service as a non-commissioned ship of the Military Sea Transportation Service from 1958 to 1971. In December 1971, the ship was transferred to the Hellenic Navy as Hephaistos (A413), a motor torpedo boat tender. Hephaistos was struck from the rolls of the Hellenic Navy in April 1976.

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