Paraná and Etendeka traps

Source: Wikipedia, the free encyclopedia.
Paraná and Etendeka traps
Paraná and Etendeka Plateau or Paraná and Etendeka Province
Large igneous province
The Paraná and Etendeka traps shown as dark purple spot on the geologic map of South America
The Paraná and Etendeka traps shown as dark purple spot on the geologic map of South America
Locationeastern Brazil, Uruguay, northwest Namibia & southwest Angola
Part ofParaná Basin
Offshore water bodiesSouthern Atlantic
AgeEarly Cretaceous
138-128 Ma
Formed byBreak-up of Pangaea
GeologySerra Geral Formation
Area
 • Total1,500,000 km2 (580,000 sq mi)
Last eruptionBarremian
A cliff at the Paraná Magmatic Province. Rio do Rastro, Santa Catarina. One can see the near vertical escarpment of silicic succession from waning-stage volcanism.

The Paraná-Etendeka Large Igneous Province (PE-LIP) (or Paraná and Etendeka Plateau; or Paraná and Etendeka Province) is a

geological basin) as well as the smaller severed portions of the flood basalts at the Etendeka traps (in northwest Namibia and southwest Angola). The original basalt flows occurred 136 to 132 million years ago. The province had a post-flow surface area of 1,000,000 square kilometres (390,000 sq mi) and an original volume projected to be in excess of 2.3 x 106 km3.[1][2]

Geodynamics

The basalt samples at Paraná and Etendeka have an age of about 132 Ma, during the

extension are probably the origin of the Paraná and Etendeka traps and it could be the origin of the Gough and Tristan da Cunha Islands as well, as they are connected by the Walvis Ridge (Gough/Tristan hotspot). The seamounts of the Rio Grande Rise (25°S to 35°S) that go eastwards from the Paraná side[4][5] are part of this traps system.[6]

Description

Interpretations of geochemistry, including

plutonic rocks related to the traps escaped crustal contamination reflecting more directly the source of the magmas in the mantle.[7]

Silicic eruptions

In Paraná, the

silicic rocks are divided into two compositional groups, the Palmas volcanics and Chapecó volcanics.[8] Palmas is recognized as composed of the five geochemical subtypes Santa Maria, Caxias do Sul, Anita Garibaldi, Clevelândia and Jacuí, while Chapecó is composed of the three geochemical subtypes Ourinhos, Tamarana and Guarapuav.[9] Eight major eruptive units, labeled PAV-A to -G and BRA-21, are recognized within Palmas volcanics.[10]

In Etendeka, individual eruptive units of

members: Naudé, Sarusas, Elliott, Khoraseb, and Ventura. The low-Ti suite is composed of eight members: Fria, Beacon, Grootberg, Wereldsend, Hoanib, Springbok, Goboboseb, and Terrace.[11] In particular, Goboboseb consists of four eruptive units, labeled Goboboseb-I to -IV.[12]

On the basis of trans-Atlantic chemostratigraphy, the low-Ti suite in Etendeka is equivalent to Palmas volcanics in Paraná,[10] and the high-Ti suite is equivalent to Chapecó volcanics.[11] At a finer scale, geochemical affinities have made tentative correlations in these pairs:[13][10][14] PAV-G of Anita Garibaldi and Beacon, PAV-B of Caxias do Sul and Springbok, PAV-A of Jacuí and Goboboseb-II, Guarapuava and Ventura, Ourinhos and Khoraseb, BRA-21 and Wereldsend, PAV-F of Caxias do Sul and Grootberg. Sarusas may correlate either to Guarapuava or Tamarana, and Fria may correlate either to Santa Maria or Clevelândia.[13][14]

Eruption style and volume

In Etendeka, the quartz latite units are interpreted to be rheomorphic

ash-flows. Each eruption produced voluminous and widespread pyroclastic sheet with thickness between 40–300 m (130–980 feet). Individual unit, within Etendeka, has a volume between 400–2,600 km3 (96–624 cubic miles) and covers an area up to 8,800 km2 (3,400 square miles).[12] No air-fall layer associated with the eruptions has been recognized.[12][15] A 18 km (11 miles) diameter, circular structure, called Messum igneous complex, is identified to be the eruptive centre for Goboboseb-I to -IV and Springbok.[16]

It was postulated that Chapecó and Palmas volcanics in Paraná are the eastward extensions of Etendeka ash-flows, so each correlation represents a huge ignimbrite eruption. The volumes of these eruptions would make them the largest known explosive eruptions on Earth.[13][15] Notably, the largest Guarapuava-Tamarana/Sarusas is estimated to have a volume of 8,600 km3 (2,100 cubic miles), which dwarfs other extremely large eruptions such as 30 million year old Wah Wah Springs and 28 million year old Fish Canyon Tuff. This interpretation, however, is disputed. Sarusas member is known to consist of 10 eruptive units hence a product of multiple eruptions.[13][17] Moreover, units of each province are not the exact correlatives of the same eruptive event but may share the same magmatic system.[10]

In contrast, Chapecó and Palmas volcanics in Paraná are not unambiguously identified as the eastward extensions of ash-flows. Most studies have characterized Chapecó and Palmas as stacks of local

low-column fountains.[23]

See also

References

  1. doi:10.1016/S1631-0713(03)00006-3
    .
  2. doi:10.1016/0895-9811(89)90012-6
    .
  3. doi:10.1016/0012-821X(96)00132-X
    .
  4. doi:10.1016/S0012-821X(03)00368-6. Archived from the original
    (PDF) on 2011-07-26.
  5. doi:10.1016/0012-821X(92)90138-L
    .
  6. ^ Brazilian 'Atlantis' found - Geologists have announced the discovery of what has been dubbed the 'Brazilian Atlantis', some 900 miles from Rio., Donna Bowater, The Daily Telegraph, 7 May 2013
  7. doi:10.1093/petrology/egx021
    .
  8. ISSN 0022-3530
    .
  9. ^ Nardy, AJR, Machado, FB, & de Oliveira, MAF (2008). The acidic Mesozoic volcanic rocks of the Paraná Basin: lithostratigraphy and geochemical-stratigraphic considerations. Brazilian Journal of Geology, 38 (1), 178-195.
  10. ^
    ISSN 0377-0273
    .
  11. ^
    ISSN 1432-0819
    .
  12. ^
    ISSN 0258-8900
    .
  13. ^
    doi:10.1016/j.earscirev.2010.07.001
    .
  14. ^ a b Sato, V. S., Nardy, A. J. R., Luchetti, A. C. F., & Navarro, J. (2016). Correlação das unidades ácidas da Província Magmática do Paraná e Província Magmática do Etendeka. In Congresso de Iniciação Científica UNESP (Vol. 1, No. 1, pp. 43-49).
  15. ^
    hdl:11449/170391
    .
  16. ISSN 0377-0273
    .
  17. ISSN 1460-2415
    .
  18. ISSN 0377-0273
    .
  19. ISSN 0377-0273
    .
  20. ISSN 0022-3530
    .
  21. ISSN 0377-0273
    .
  22. ISSN 0895-9811
    .
  23. ISSN 0377-0273
    .

Further reading

  • Peate DW (1997). "The Parana-Etendeka Province" (PDF). In Mahoney JJ, Coffin MF (eds.). Large Igneous Provinces: continental, oceanic, and planetary flood volcanism. Geophysical Monograph. Vol. 100. Washington, DC: American Geophysical Union. pp. 217–245.

External links

Retrieved from "https://en.wikipedia.org/w/index.php?title=Paraná_and_Etendeka_traps&oldid=1219310005"