The Gulf of Cádiz (, ) is the arm of the

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

between Cabo de Santa Maria, the southernmost point of mainland Portugal; and

Cape Trafalgar Cape Trafalgar (; ) is a headland in the Province of Cádiz in the southwest of Spain. The 1805 naval Battle of Trafalgar, in which the Royal Navy commanded by Admiral Horatio Nelson decisively defeated Napoleon's combined Spanish and French f ...

on the Spanish coast at the western end of the

Strait of Gibraltar The Strait of Gibraltar is a narrow strait that connects the Atlantic Ocean to the Mediterranean Sea and separates Europe from Africa. The two continents are separated by 7.7 nautical miles (14.2 kilometers, 8.9 miles) at its narrowest point. Fe ...

. Two major

river A river is a natural stream of fresh water that flows on land or inside Subterranean river, caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of ...

s, the

Guadalquivir The Guadalquivir (, also , , ) is the fifth-longest river in the Iberian Peninsula and the second-longest river with its entire length in Spain. The Guadalquivir is the only major navigable river in Spain. Currently it is navigable from Seville ...

and the

Guadiana The Guadiana River ( , , , ) is an international river defining a long stretch of the Portugal-Spain border, separating Extremadura and Andalusia (Spain) from Alentejo and Algarve (Portugal). The river's basin extends from la Mancha and the e ...

, as well as smaller rivers, like the

Odiel The Odiel () is a river in the Atlantic basin in southern Spain, more precisely in the province of Huelva, Andalusia. It originates at Marimateos in the Sierra de Aracena at an elevation of above sea level. At the Punta del Sebo, it joins th ...

, the

Tinto Tinto is an isolated hill in the south of the Central Lowlands just to the north of the Southern Uplands of Scotland. It comprises little more than one top, which stands on the west bank of the River Clyde, some west of Biggar. The peak is a ...

, and the Guadalete, reach the

ocean The ocean is the body of salt water that covers approximately 70.8% of Earth. The ocean is conventionally divided into large bodies of water, which are also referred to as ''oceans'' (the Pacific, Atlantic, Indian Ocean, Indian, Southern Ocean ...

here. The Gulf of Cádiz is located in the north-eastern Atlantic Ocean between 34°N and 37°15′N and 6°W to 9°45′W. It is enclosed by the southern Iberian and northern Moroccan margins, west of

Geology

The geological history of the Gulf of Cádiz is intimately related to

plate tectonic Plate may refer to: Cooking * Plate (dishware), broad, mainly flat vessel commonly used to serve food * Plates, tableware, dishes or dishware used for setting a table, serving food and dining * Plate, the content of such a plate (for example: r ...

interaction between Southern

Eurasia Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...

and North Africa and is driven by two major mechanisms: *

subduction Subduction is a geological process in which the oceanic lithosphere and some continental lithosphere is recycled into the Earth's mantle at the convergent boundaries between tectonic plates. Where one tectonic plate converges with a second p ...

associated with the westward emplacement of the Gibraltar Arc and formation of the Gulf of Cádiz accretionary wedge. The current activity of the subduction is unclear, with some advocating ongoing active subduction. Others suggest that subduction is inactive and that a new plate boundary has recently formed along a series of prominent WNW–ESE trending lineaments acting as a dextral strike-slip (transform) plate boundary. * oblique lithosphere collision between

Iberia The Iberian Peninsula ( ), also known as Iberia, is a peninsula in south-western Europe. Mostly separated from the rest of the European landmass by the Pyrenees, it includes the territories of peninsular Spain and Continental Portugal, compri ...

and

Nubia Nubia (, Nobiin language, Nobiin: , ) is a region along the Nile river encompassing the area between the confluence of the Blue Nile, Blue and White Nile, White Niles (in Khartoum in central Sudan), and the Cataracts of the Nile, first cataract ...

. Oblique convergence between Africa (Nubia) and Iberia (Eurasia) occurs here at about per year in a NW–SE direction. Some have suggested this may also be causing active thrusting in the Gulf of Cádiz. GulfCadiz fault map

It is now well established that the whole area is under compressive deformation and that mud volcanism and processes associated with the escape of

hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and Hydrophobe, hydrophobic; their odor is usually fain ...

-rich fluids sustain a broad diversity of chemosynthetic assemblages. The accretionary wedge formed by subduction represents an extensive area which encompasses over forty

mud volcano A mud volcano or mud dome is a landform created by the eruption of mud or Slurry, slurries, water and gases. Several geological processes may cause the formation of mud volcanoes. Mud volcanoes are not true Igneous rock, igneous volcanoes as th ...

es (a type of

cold seep A cold seep (sometimes called a cold vent) is an area of the ocean floor where seepage of fluids rich in hydrogen sulfide, methane, and other hydrocarbons occurs, often in the form of a brine pool. ''Cold'' does not mean that the temperature ...

), at depths ranging from (confirmed by coring), and active methane seepage has been documented on several locations.

Biota

The occurrence of chemosymbiotic biota in the extensive mud volcano fields of the Gulf of Cádiz was first reported in 2003. There were found mainly pogonophoran worms, but also gastropods and bivalves, polychaetes, crustaceans and echinoderms. There were also recorded dead corals of genera '' Madrepora'' and '' Lophelia''. The chemosymbiotic

bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...

s collected from the mud volcanoes of the Gulf of Cádiz were reviewed in 2011. There were reported the following species of chemosymbiotic bivalves of

Solemyidae Solemyidae is a family (biology), family of saltwater clams, marine (ocean), marine protobranch bivalve mollusks in the order (biology), order Solemyida. Biology Solemyids are remarkable in that their digestive tract is either extremely small or ...

: '' Acharax gadirae'', '' Solemya elarraichensis'';

Mytilidae The Mytilidae are a family (biology), family of small to large Marine life, marine and Brackish water, brackish-water bivalve molluscs in the order (biology), order Mytilida. One of the genera, ''Limnoperna fortunei, Limnoperna'', even inhabits f ...

: '' Bathymodiolus mauritanicus'', ''

Idas In Greek mythology, Idas (; ), was a Messenian prince. He was one of the Argonauts, a participant in the hunt for the Calydonian Boar and contender with the gods. Idas was described as keen and spirited.Hyginus, ''Fabulae'14/ref> Family Idas ...

'' sp.; Lucinidae: '' Lucinoma asapheus''; Thyasiridae: '' Thyasira vulcolutre'', '' Spinaxinus sentosus''; Vesicomyidae: '' Isorropodon perplexum'', '' Isorropodon megadesmus'', '' Callogonia cyrili'', '' Christineconcha regab'', '' Laubiericoncha chuni'' and '' Pliocardia'' sp. There is high degree of

endemism Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

within chemosymbiotic bivalve assemblages.

References

{{DEFAULTSORT:Gulf Of Cadiz Gulfs of the Atlantic Ocean Bodies of water of Portugal Gulfs of Spain Geography of Europe

Geology

Biota

See also

References