Paraná and Etendeka traps

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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 traps (or Paraná and Etendeka Plateau; or Paraná and Etendeka Province) comprise a large igneous province which includes both the main Paraná traps (in Paraná Basin, a South American 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 128 to 138 million years ago. The province had a post-flow surface area of 1.5 x 106 km² (580,000 miles²) and an original volume projected to be in excess of 2.3 x 106 km³.[1][2]

The basalt samples at Paraná and Etendeka have an age of about 132 Ma.[3] Indirectly, the rifting and 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]

Interpretations of geochemistry, including isotopes, have led geologists to conclude that the magmas forming the traps and associated igneous rocks formed by melting of asthenosphic mantle due to the arrival of a mantle plume to the base of Earth's lithosphere. Then much of the magma was contaminated with crustal materials prior to their eruption. Some plutonic rocks related to the traps escaped crustal contamination reflecting more directly the source of the magmas in the mantle.[7]

A type of rock called ignimbrite is found in some parts of the traps. It is indicative of explosive volcanic activity. The Paraná Traps possibly contains the site of the single largest explosive volcanic eruption known in Earth's history.[8]

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References[edit]

  1. ^ Courtillot, Vincent E.; Renneb, Paul R. (January 2003). "Sur l'âge des trapps basaltiques (On the ages of flood basalt events)". Comptes Rendus Geoscience. 335 (1): 113–140. doi:10.1016/S1631-0713(03)00006-3. 
  2. ^ Fodor, R.V.; McKee, E.H.; Roisenberg, A. (1989). "Age distribution of Serra Geral (Paraná) flood basalts, southern Brazil". Journal of South American Earth Sciences. 2 (4): 343–349. Bibcode:1989JSAES...2..343F. doi:10.1016/0895-9811(89)90012-6. 
  3. ^ Stewart, Kathy; Turner, Simon; Kelley, Simon; Hawkesworth, Chris; Kirstein, Linda; Mantovani, Marta (1996). "3-D, 40Ar-39Ar geochronology in the Paraná continental flood basalt province". Earth and Planetary Science Letters. 143 (1-4): 95–109. doi:10.1016/0012-821X(96)00132-X. 
  4. ^ O'Neill, C.; Müller, R. D.; Steinberger, B. (2003). "Revised Indian plate rotations based on the motion of Indian Ocean hotspots" (PDF). Earth and Planetary Science Letters. 215: 151–168. Bibcode:2003E&PSL.215..151O. doi:10.1016/S0012-821X(03)00368-6. 
  5. ^ O'Connor, J. M.; le Roex, A. P. (1992). "South Atlantic hot spot-plume systems. 1: Distribution of volcanism in time and space". Earth and Planetary Science Letters. 113: 343–364. Bibcode:1992E&PSL.113..343O. 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. ^ Owen-Smith, T.M.; Ashwal, L.D.; Sudo, M.; Trumbull, R.B. (2017). "Age and Petrogenesis of the Doros Complex, Namibia, and Implications for Early Plume-derived Melts in the Paraná–Etendeka LIP". Journal of Petrology. 58 (3): 423–442. 
  8. ^ Scott E. Bryan; Ingrid Ukstins Peate; David W. Peate; Stephen Self; Dougal A. Jerram; Michael R. Mawby; J.S. Marsh; Jodie A. Miller (2010). "The largest volcanic eruptions on Earth". Earth-Science Reviews. 102: 207. doi:10.1016/j.earscirev.2010.07.001. 
  • Peate DW (1997). "The Parana-Etendeka Province" (PDF). In Mahoney JJ, Coffin MF. Large Igneous Provinces: continental, oceanic, and planetary flood volcanism. Geophysical Monograph. 100. Washington, DC: American Geophysical Union. pp. 217–245. 

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