Pasto Ventura

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Coordinates: 26°50′00″S 67°17′30″W / 26.83333°S 67.29167°W / -26.83333; -67.29167
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Pasto Ventura
Pasto Ventura is located in Argentina
Pasto Ventura
Pasto Ventura
Highest point
Coordinates26°50′00″S 67°17′30″W / 26.83333°S 67.29167°W / -26.83333; -67.29167[1]

Pasto Ventura is an area in the

tuff rings and two maars. The volcanoes are accompanied by pyroclastic deposits and their total volume reaches about 0.42 cubic kilometres (0.10 cu mi). Argon-argon dating
has yielded ages ranging from 1.3 million years to about 270,000 years for volcanic rocks in the field.

Faults have displaced several of the cones, and their movement reflects a tectonic environment characterized by ongoing extension of the

arid
but may have been wetter in the past. Vegetation consists of sparse bush.

Geography and geomorphology

Pasto Ventura lies in the southern Puna region[2] of northwestern Argentina.[3] It lies about 40 kilometres (25 mi) southwest of El Peñón, Catamarca[4] and Provincial Route 43 [es] between El Peñón and Los Nacimientos passes northeast of the field.[5] The Pasto Ventura pass was an important route in the region during the pre-modern era.[6]

The landscape is characterized by ridges, valleys and small volcanoes.

eruption fissure has been reported[9] and additional volcanoes may exist but are buried under lava.[1] None of these volcanoes has a volume exceeding 0.2 cubic kilometres (0.048 cu mi) and the total volume reaches only 0.42 cubic kilometres (0.10 cu mi), making them small edifices by the standard of the Puna.[10] The frequency of volcanic landforms per unit area is also low[9] with only seven vents every 100 square kilometres (39 sq mi).[11]

Various volcanic forms are recognized in the Pasto Ventura area. Cinder cones, which form the majority of volcanoes there, reach heights of 60–100 metres (200–330 ft) and are capped by

lacustrine deposits.[13] Maars are unusual in the Puna.[9]

The scoria cones are mainly formed by deposits of

aa lava.[8] Pyroclastic material was often rafted by lava flows, forming isolated deposits on these, and spatter deposits were generated by Hawaii-like fire fountaining.[15] Ultimately, the variety of volcanic landforms at Pasto Ventura is a consequence of interactions between various factors, such as the speed at which magma rose.[16]

captured by drainages from outside the Puna.[21]

Geology

Eastward

high plateau, which with a length of 1,500 kilometres (930 mi) and a width of 300–500 kilometres (190–310 mi) is the second largest such plateau in the world. The northern Altiplano has a large central basin and a thick underlying crust, while the Puna has a rugged landscape with a number of intervening basins.[22] The Altiplano-Puna high plateau is undergoing horizontal extension, perhaps due to the weight of the high plateau overcoming the compressional tectonic forces, due to delamination of the crust inducing uplift[2] or in the case of the southern Puna by southward shearing of the plateau.[1] In the Puna, extension appears to have begun between 10 and 5 million years ago.[23] A basin formed at Pasto Ventura during the Miocene and was filled with thick sedimentary deposits;[7] it is the only exposed basin in the Puna.[17]

The high plateau is volcanically active, with various

calc-alkaline composition. The magma feeding these volcanic centres appears to come from the asthenosphere and the ascent of mafic magmas is facilitated by the extensional tectonic regime[25] and by faulting.[24]

Local

The

ultramafic rocks of Paleozoic age;[26] these metamorphic rocks are also known as the Puncoviscana Formation.[19] There are Paleogene-Neogene continental sequences.[26] It is mostly buried beneath Quaternary sediments; outcrops have characteristic dark colours. The Quaternary sediments in turn contain both aeolian, colluvium and alluvium-derived sediments;[1] older aeolian sediments of Miocene age are also found.[27] A major regional tectonic lineament known as Culampaja passes through Pasto Ventura[28] and the Vicuña Pampa volcanic complex lies east of the area.[7]

The volcanic rocks at Pasto Ventura are formed by

xenocryst quartz; basement rocks are present as xenoliths[8] and occur as blocks in maar deposits.[13]

Famatinian Orogeny c. 485 million years ago.[33]

Climate and vegetation

The regional climate is extremely

bush.[1]

Eruption and faulting history

The oldest volcanic rocks in the Pasto Ventura region are of Miocene age. Among the old volcanism are basaltic andesite lava flows in the eastern part of the field; they are partially buried by sediments and have lost their surface features. Other volcanic centres are well preserved despite their age, as erosion rates are low on the Puna plateau.[1] The faults include both faults that began to form in the Quaternary[38] and older faults which were later reactivated.[39]

GPS.[42]

References

  1. ^ a b c d e f g h i j Zhou, Schoenbohm & Cosca 2013, p. 22.
  2. ^ a b Zhou, Schoenbohm & Cosca 2013, p. 19.
  3. ^ a b Zhou & Schoenbohm 2015, p. 344.
  4. ^ a b c d Filipovich, Rubén; Santillán, Ana; Baez, Walter; Viramonte, Jose (2014). Caracterización del volcanismo monogénico básico de la región de Pasto Ventura, Puna Austral. XIX Congreso Geológico Argentino (in Spanish). Córdoba, Argentina. Retrieved 14 April 2020.
  5. ^ a b Maidana, Nora I.; Seeligmann, Claudia (July 2006). "Diatomeas (Bacillariophyceae) de Ambientes Acuáticos de Altura de la Provincia de Catamarca, Argentina II" [Diatoms (Bacillariophyceae) from Altitude Aquatic Environments of the Province of Catamarca, Argentina II]. Boletín de la Sociedad Argentina de Botánica (in Spanish). 41 (1–2): 1–13.
  6. S2CID 251996977
    .
  7. ^ a b c d e Filipovich et al. 2019, p. 305.
  8. ^ a b c d e f g Filipovich et al. 2019, p. 311.
  9. ^ a b c Haag et al. 2019, p. 201.
  10. ^ a b c d Filipovich et al. 2019, p. 308.
  11. ^ a b Haag et al. 2019, p. 202.
  12. ^ Filipovich et al. 2019, p. 309.
  13. ^ a b Filipovich et al. 2019, p. 315.
  14. ^ Zhou & Schoenbohm 2015, p. 343.
  15. ^ a b Filipovich et al. 2019, p. 313.
  16. ^ Filipovich et al. 2019, p. 326.
  17. ^ a b Zhou & Schoenbohm 2015, p. 336.
  18. ^ Zhou & Schoenbohm 2015, p. 345.
  19. ^ a b Zhou & Schoenbohm 2015, p. 340.
  20. ^ Penck 1920, p. 301.
  21. ^ Penck 1920, p. 396.
  22. ^ Zhou, Schoenbohm & Cosca 2013, p. 20.
  23. ^ Zhou, Schoenbohm & Cosca 2013, p. 21.
  24. ^ a b Filipovich et al. 2019, p. 302.
  25. ^ Zhou, Schoenbohm & Cosca 2013, pp. 20–21.
  26. ^ a b c Filipovich et al. 2019, p. 304.
  27. S2CID 245981795
    .
  28. ^ Zhou, Schoenbohm & Cosca 2013, p. 31.
  29. ^
    ISBN 978-0-8137-0013-7
    .
  30. ^ Zhou & Schoenbohm 2015, p. 349.
  31. ^ Filipovich et al. 2019, p. 321.
  32. ^ Filipovich et al. 2019, p. 303.
  33. Bibcode:2008AGUFM.V31C2182D
    .
  34. ^ Filipovich et al. 2019, p. 306.
  35. ^ Filipovich et al. 2019, p. 3214.
  36. ^ Haag et al. 2019, p. 203.
  37. hdl:10915/20999
    .
  38. ^ Zhou, Schoenbohm & Cosca 2013, p. 24.
  39. ^ Zhou, Schoenbohm & Cosca 2013, p. 25.
  40. ^ Zhou, Schoenbohm & Cosca 2013, p. 28.
  41. ^ Zhou, Schoenbohm & Cosca 2013, p. 29.
  42. ^ Zhou, Schoenbohm & Cosca 2013, p. 30.

Sources

External links
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