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The Adamastor Ocean was a "proto-Atlantic" ocean that formed with the break-up of the Rodinia supercontinent 780-750 . It separated the
Río de la Plata Craton The Rio de la Plata Craton (RPC) is a medium-sized continental block found in Uruguay, eastern Argentina and southern Brazil. During its complex and protracted history it interacted with a series other blocks and is therefore considered importan ...
from the Congo Craton. The inversion of the Adamastor Ocean began about 640 Ma with the development of a large
back-arc basin A back-arc basin is a type of geologic basin, found at some convergent plate boundaries. Presently all back-arc basins are submarine features associated with island arcs and subduction zones, with many found in the western Pacific Ocean. Most ...
along the western margin of the
Kalahari Craton The Kalahari Craton is a craton, an old and stable part of the continental lithosphere, that occupies large portions of South Africa, Botswana, Namibia and Zimbabwe. It consists of two cratons separated by the Limpopo Belt: the larger Kaapvaal ...
, and the ocean closed when Río de la Plata collided with Kalahari about 545 Ma along the sinistral
Sierra Ballena Shear Zone Sierra Ballena Shear Zone or SBSZ is a sinistral strike-slip shear zone running across the Uruguayan Shield in eastern Uruguay and the Brazilian state of Rio Grande do Sul. The system was last active in the Precambrian The Precambrian (or Pr ...
. The São Francisco Craton and the Río de la Plata Craton amalgamated 630–620 Ma, closing the Adamastor Ocean on the South American side and forming the Mantiqueira Mountains around 600 Ma. In 2020 a group of geologists proposed an alternative model for the Adamastor Ocean in which it is reduced to a intracontinental rift system with only some minor oceanic crust developing in its southern part.


Etymology

South African geologist Chris Hartnady named the Precambrian ocean after the mythical giant Adamastor from
Luís de Camões Luís Vaz de Camões (; sometimes rendered in English as Camoens or Camoëns, ; c. 1524 or 1525 – 10 June 1580) is considered Portugal's and the Portuguese language's greatest poet. His mastery of verse has been compared to that of Shakespe ...
's poem ''
Os Lusíadas ''Os Lusíadas'' (), usually translated as ''The Lusiads'', is a Portuguese epic poem written by Luís Vaz de Camões ( – 1580) and first published in 1572. It is widely regarded as the most important work of Portuguese-language literature ...
'' which celebrates
Vasco da Gama Vasco da Gama, 1st Count of Vidigueira (; ; c. 1460s – 24 December 1524), was a Portuguese explorer and the first European to reach India by sea. His initial voyage to India by way of Cape of Good Hope (1497–1499) was the first to link ...
's discovery of the sea route to India. Hartnady thought it an appropriate name since the demigod was transformed into stone and personified the
Cape of Storms The Cape of Good Hope ( af, Kaap die Goeie Hoop ) ;''Kaap'' in isolation: pt, Cabo da Boa Esperança is a rocky headland on the Atlantic coast of the Cape Peninsula in South Africa. A common misconception is that the Cape of Good Hope is t ...
and since
Atlas An atlas is a collection of maps; it is typically a bundle of maps of Earth or of a region of Earth. Atlases have traditionally been bound into book form, but today many atlases are in multimedia formats. In addition to presenting geograp ...
and Iapetus are associated with the oceans of the northern Atlantic, the North Atlantic Ocean and the Iapetus Ocean respectively.


Geological history

The Adamastor Ocean was narrow in the north, perhaps similar to the Red Sea, but widened southward. C isotope analyses indicate that the ocean water was strongly stratified and thus that it must have been a closed ocean, similar to the Mediterranean, but probably covered by ice during the Sturtian and Marinoan glaciations. Ocean floor adjacent to the Marmora Terrane (near the
Orange River The Orange River (from Afrikaans/ Dutch: ''Oranjerivier'') is a river in Southern Africa. It is the longest river in South Africa. With a total length of , the Orange River Basin extends from Lesotho into South Africa and Namibia to the nort ...
in South Africa) formed 740–580 Ma, dates that represent the first rifting and the first accretion respectively. The Adamastor Ocean closed in three episodes: the Río de la Plata Craton first collided with the Congo Craton, which then collided with the Kalahari Craton, which finally collided with Río de la Plata.


See also

* Brasiliano orogeny * Geology of Namibia


References


Notes


Sources

* * * * * {{Refend Historical oceans Precambrian Africa Precambrian South America