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The Paraná-Etendeka traps (or Paraná and Etendeka Plateau; or Paraná and Etendeka Province) comprise a
large igneous province A large igneous province (LIP) is an extremely large accumulation of igneous rocks, including intrusive (sills, dikes) and extrusive (lava flows, tephra deposits), arising when magma travels through the crust towards the surface. The formation ...
that includes both the main Paraná traps (in
Paraná Basin The Paraná Basin ( pt, Bacia do Paraná, es, Cuenca del Paraná) is a large cratonic sedimentary basin situated in the central-eastern part of South America. About 75% of its areal distribution occurs in Brazil, from Mato Grosso to Rio Grande d ...
, a
South American South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...
geological basin) as well as the smaller severed portions of the
flood basalt A flood basalt (or plateau basalt) is the result of a giant volcanic eruption or series of eruptions that covers large stretches of land or the ocean floor with basalt lava. Many flood basalts have been attributed to the onset of a hotspot reac ...
s at the Etendeka traps (in northwest
Namibia Namibia (, ), officially the Republic of Namibia, is a country in Southern Africa. Its western border is the Atlantic Ocean. It shares land borders with Zambia and Angola to the north, Botswana to the east and South Africa to the south and ea ...
and southwest
Angola , national_anthem = "Angola Avante"() , image_map = , map_caption = , capital = Luanda , religion = , religion_year = 2020 , religion_ref = , coordinat ...
). The original basalt flows occurred 138 to 128 million years ago. The province had a post-flow surface area of and an original volume projected to be in excess of 2.3 x 106 km³.


Geodynamics

The basalt samples at Paraná and Etendeka have an age of about 132 Ma, during the
Valanginian In the geologic timescale, the Valanginian is an age or stage of the Early or Lower Cretaceous. It spans between 139.8 ± 3.0 Ma and 132.9 ± 2.0 Ma (million years ago). The Valanginian Stage succeeds the Berriasian Stage of the Lower Cretace ...
stage of the
Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145& ...
. Indirectly, the rifting and
extension Extension, extend or extended may refer to: Mathematics Logic or set theory * Axiom of extensionality * Extensible cardinal * Extension (model theory) * Extension (predicate logic), the set of tuples of values that satisfy the predicate * Ext ...
are probably the origin of the Paraná and Etendeka traps and it could be the origin of the
Gough Gough ( ) is a surname. The surname probably derives from the Welsh (English: "red"), given as a nickname to someone with red hair or a red complexion or as a reduced form of the Irish McGough which itself is an Anglicized form of Gaelic , a patr ...
and
Tristan da Cunha Tristan da Cunha (), colloquially Tristan, is a remote group of volcano, volcanic islands in the South Atlantic Ocean. It is the Extreme points of Earth, most remote inhabited archipelago in the world, lying approximately from Cape Town, Sou ...
Islands as well, as they are connected by the
Walvis Ridge The Walvis Ridge (''walvis'' means whale in Dutch and Afrikaans) is an aseismic ocean ridge in the southern Atlantic Ocean. More than in length, it extends from the Mid-Atlantic Ridge, near Tristan da Cunha and the Gough Islands, to the Africa ...
(Gough/
Tristan hotspot The Tristan hotspot is a volcanic hotspot which is responsible for the volcanic activity which forms the volcanoes in the southern Atlantic Ocean. It is thought to have formed the island of Tristan da Cunha and the Walvis Ridge on the African Plat ...
). The seamounts of the
Rio Grande Rise The Rio Grande Rise, also called the Rio Grande Elevation or Bromley Plateau, is an aseismic ocean ridge in the southern Atlantic Ocean off the coast of Brazil. Together with the Walvis Ridge off Africa, the Rio Grande Rise forms a V-shaped str ...
(25°S to 35°S) that go eastwards from the Paraná side are part of this traps system.


Description

Interpretations of geochemistry, including
isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers ( mass num ...
s, have led geologists to conclude that the magmas forming the traps and associated
igneous rock Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma o ...
s originated by
melting Melting, or fusion, is a physical process that results in the phase transition of a substance from a solid to a liquid. This occurs when the internal energy of the solid increases, typically by the application of heat or pressure, which in ...
of asthenosphic mantle due to the arrival of a
mantle plume A mantle plume is a proposed mechanism of convection within the Earth's mantle, hypothesized to explain anomalous volcanism. Because the plume head partially melts on reaching shallow depths, a plume is often invoked as the cause of volcanic hot ...
to the base of Earth's
lithosphere A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust and the portion of the upper mantle that behaves elastically on time scales of up to thousands of years ...
. Then much of the magma was contaminated with crustal materials prior to their eruption. Some
plutonic rock Intrusive rock is formed when magma penetrates existing rock, crystallizes, and solidifies underground to form '' intrusions'', such as batholiths, dikes, sills, laccoliths, and volcanic necks.Intrusive RocksIntrusive rocks accessdate: March ...
s related to the traps escaped crustal contamination reflecting more directly the source of the magmas in the mantle. A type of rock called
ignimbrite Ignimbrite is a type of volcanic rock, consisting of hardened tuff. Ignimbrites form from the deposits of pyroclastic flows, which are a hot suspension of particles and gases flowing rapidly from a volcano, driven by being denser than the surro ...
is found in some parts of the traps indicating
explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An expl ...
volcanic activity. The Paraná Traps possibly contains the site of the single largest explosive volcanic eruption known in Earth's history.


See also

*
Geology of Paraguay The country of Paraguay lies geologically at the borderzone between several cratons. Due to thick Cenozoic sediment cover and regolith development few outcrops are available in Paraguay.Fúlfaro V. JGeology of Eastern Paraguay/ref> East of Para ...
* Geology of Uruguay *
Paraná Basin The Paraná Basin ( pt, Bacia do Paraná, es, Cuenca del Paraná) is a large cratonic sedimentary basin situated in the central-eastern part of South America. About 75% of its areal distribution occurs in Brazil, from Mato Grosso to Rio Grande d ...
* Uruguayan dyke swarms


References


Further reading

*


External links

* {{DEFAULTSORT:Parana And Etendeka Traps Large igneous provinces Barremian Stage Hauterivian Stage Valanginian Stage Early Cretaceous Africa Early Cretaceous South America Cretaceous volcanism Volcanism of Brazil Volcanism of Angola Volcanism of Namibia Cretaceous Argentina Geology of Argentina Cretaceous Brazil Geology of Brazil Cretaceous Uruguay Geology of Uruguay Stratigraphy of Argentina Stratigraphy of Uruguay