Mentolat

Coordinates: 44°41′48″S 73°04′33″W / 44.69667°S 73.07583°W / -44.69667; -73.07583
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Mentolat
Mentolat is located in Chile
Mentolat
Mentolat
Highest point
Ultra
Coordinates44°41′48″S 73°04′33″W / 44.69667°S 73.07583°W / -44.69667; -73.07583[4]
Geography
LocationChile
Parent rangeAndes
Geology
Mountain typeStratovolcano
Last eruption1710 ± 5 years[5]

Mentolat is an ice-filled, 6 km (4 mi) wide

lava flows and pyroclastic flows. The caldera is filled with a glacier
.

Little is known of the eruptive history of Mentolat, but it is thought to be young, with a possible eruption in the early 18th century that may have formed lava flows on the western slope. The earliest activity occurred during the Pleistocene, and Mentolat has had some major explosive eruptions during the Holocene.

Etymology and alternative spellings

The etymology of Mentolat has been tentatively linked to Men (o) lat, which in the Chono language means "to decipher". Mentolat was referred to as Montalat on a map of the early 20th century, and other spellings such as Menlolat, Montalat, Montolot and Matalot have been identified.[6]

Geomorphology and geography

Mentolat lies on the central part of

Aysen Region,[7] from which it is separated by the Puyuhuapi strait.[3] Other towns in the area are: La Junta, Puerto Gala, Puerto Gaviota and Puyuhuapi.[8] Like most volcanoes in the region, Mentolat is far away from roads and difficult to access.[9]

Mentolat is located in the Southern Volcanic Zone,

Cerro Hudson.[11]

Mentolat is a

lava flows and pyroclastic flows,[12] and covers a surface area of 204 square kilometres (79 sq mi).[8] The total volume of the edifice has been estimated to be about 36 cubic kilometres (8.6 cu mi),[13] 46.3 cubic kilometres (11.1 cu mi),[14] or 88.2 cubic kilometres (21.2 cu mi).[8] A 6 kilometres (3.7 mi) wide caldera is filled with ice,[15] which covered a surface area of 3.35 square kilometres (1.29 sq mi) in 2011. In 1979, the glacier covered a surface area almost 2.5 times larger.[16] Alternatively, the caldera may be filled with a lava dome,[9] or an ice covered lava dome.[17] The caldera may have formed during one of Mentolat's large explosive eruptions.[18]

The composition of the rocks ranges from

orthopyroxene and plagioclase.[15] Mentolat tephras have noticeably lower potassium contents than the tephras of other volcanoes in the region[18] and its magmas appear to originate from parental melts that contain more water and volatiles than the parental melts of the magmas of other volcanoes.[19] The magmas are stored at a depth of about 5 kilometres (3.1 mi).[20]

Geology

The

Chile Rise intersects the trench the Nazca Plate ends and the Antarctic Plate begins. This plate also subducts farther south beneath the South America Plate but at a lower pace of 1.85 centimetres per year (0.73 in/year).[21] Part of the Nazca Plate has been shoved over the South America Plate at the Taitao Peninsula resulting in the formation of the Taitao ophiolite.[22] A number of fracture zones cross the Nazca Plate and are subducted in the trench; one of these is subducted directly under Mentolat and may explain anomalous traits of the Mentolat magmas.[23]

The

Austral Volcanic Zone. These volcanic zones are separated by gaps where no recent volcanic activity has occurred.[10] These gaps are not static; the gap separating the Austral and the Southern Volcanic Zones has been moving northward for the past 15-20 million years.[24] The Southern Volcanic Zone itself is subdivided into additional volcanic zones, the Northern, Transitional, Central and Southern Southern Volcanic Zone[13] and contains over two calderas and over 60 volcanoes with Quaternary activity.[25]

More volcanoes in the neighbourhood of Mentolat include

adakitic hornblende andesites and dacites.[27]

A major geological structure in the region is the Northern

metamorphic rocks west and volcanic rocks east of the batholith.[28][29]

Climate and vegetation

Temperatures in the region range from 8–13 °C (46–55 °F) and precipitation can reach 7,500 millimetres (300 in) thanks to the

orographic precipitation triggered by the Andes. The vegetation of the area is formed by evergreen temperate rainforests.[30]

Until 17,800 years before present, the region southeast of Hudson was covered by the glaciers of the last ice age. Their retreat left a series of lakes that caught tephra deposited by volcanic activity.[24]

Eruptive history

Eruptive activity at Mentolat has been ongoing since the Pleistocene,

Laguna Potrok Aike may be linked to Mentolat[31] and other explosive eruptions took place over 17,340 years ago. An eruption during the late Glacial formed the MENo tephra[18] and another eruption 11,700 years ago produced about 1.8 cubic kilometres (0.43 cu mi) of tephra.[32] The volcanic activity has been inferred from tephra layers in lakes and outcrops,[30] about 13 eruptions have been identified with the help of tephrochronology.[13]

A major eruption of Mentolat occurred during the

before present, as determined by radiocarbon dating.[33] The MEN1 ash has been attributed to a more recent eruption, between 2,510 ± 30 and 3,890 ± 30 years ago.[7]

Less than 6,960 years before present, a basaltic andesite-andesite ash of yellow ochre colour was erupted from Mentolat. The yellow-grey MEN2 ash has been dated by radiocarbon dating to be over 90 ± 30 years before present.[7][9] This eruption had a minimum volume of 3.7 cubic kilometres (0.89 cu mi).[34] Additional tephra layers indicate eruptions less than 2,560 and 4,320 years ago, along with a number of smaller eruptions.[17][18]

Early in the 18th century, Mentolat erupted and formed lava flows on its western flank. These are Mentolat's best preserved volcanic deposits.[3][15] The eruption deposited lapilli pumice.[35] No historical records of activity exist, however,[9] although reports by Serrano in the 18th century may refer to a lava flow from Mentolat.[3] The most recent eruption may have been in 1850,[8] or 1710 ± 5.[3]

Large explosive eruptions in the southern segment of the Southern Volcanic Zone occur on average every 725 years,[36] and tephras from volcanoes in the Southern Volcanic Zone have been transported over large distances.[27] The largest Holocene volcanic eruption of the Southern Andes occurred 6,700 years before present at Cerro Hudson.[37] Tephra layers found at Mallín El Embudo have been attributed to Mentolat, as well as to Melimoyu and Cerro Hudson.[38]

Threats

Large explosive eruptions have occurred in the Southern Volcanic Zone; at least 25 large eruptions occurred in the Holocene; similar, future eruptions could have regional or even hemispheric effects as observed with the

SERNAGEOMIN publishes a volcano hazard level for Mentolat.[8]

Ash fall from volcanic eruptions affects the ecosystem. Trees lose their leaves, plants in the forest understory are buried, the forest canopy opens and plants which do not tolerate shadowing can grow.[38]

Further hazards exist in the form of snowpack on about half of the volcanoes;[11] under the influence of pyroclastic flows, the snowpack can melt, generating dangerous lahars such as the one generated by the 1985 eruption of Nevado del Ruiz volcano in Colombia. This eruption claimed 23,000 fatalities, and lahars are a major cause of volcanic eruption associated fatalities.[2]

See also

References

  1. ^ a b c d Fontijn et al., 2014, p.72
  2. ^ a b Rivera and Bown 2013, p.346
  3. ^ a b c d e f g h "Mentolat". Global Volcanism Program. Smithsonian Institution.
  4. ^ a b "Argentina and Chile, Southern: Patagonia Ultra-Prominences" Peaklist.org. Retrieved 16 April 2012.
  5. ^ a b Gallego et al., 2010, p.1481
  6. ISSN 0071-1713
    .
  7. ^ a b c d e Mella et al. 2012, p.580
  8. ^ a b c d e "Mentolat - Sernageomin". www.sernageomin.cl (in Spanish). Archived from the original on 19 February 2017. Retrieved 7 January 2017.
  9. ^
    ISSN 0716-0208
    .
  10. ^ a b Fontijn et al., 2014, p.73
  11. ^ a b c Fontijn et al., 2014, p.74
  12. ^ a b Corbella and Lara 2008, p.101
  13. ^ a b c Weller and Stern 2018, p.235
  14. doi:10.1016/j.jvolgeores.2011.03.011
    .
  15. ^ a b c d Rivera and Bown 2013, p.349
  16. ^ Rivera and Bown 2013, p.351
  17. ^ a b c Weller et al. 2015, p.5
  18. ^
    ISSN 0718-7106
    .
  19. ^ Weller and Stern 2018, p.240
  20. doi:10.1038/s43247-023-01040-9
    .
  21. ^ Gallego et al., 2010, p.1479
  22. ^ a b Gallego et al., 2010, p.1480
  23. ^ Weller and Stern 2018, p.242
  24. ^ a b Weller et al. 2015, p.3
  25. ^ Weller et al. 2019, p.283
  26. ^ Weller et al. 2015, p.1
  27. ^ a b Corbella and Lara 2008, p.107
  28. ^ Rivera and Bown 2013, p.347
  29. S2CID 53481295
    .
  30. ^
    S2CID 54943497
    .
  31. ISSN 0277-3791
    .
  32. ^ Weller et al. 2019, p.292
  33. ^
    doi:10.1016/j.earscirev.2013.03.007
    .
  34. ^ a b Mella et al. 2012, p.581
  35. ISBN 9780081004050
    .
  36. ^ Corbella and Lara 2008, p.106
  37. ^ Corbella and Lara 2008, p.105
  38. ^
    ISSN 1814-9332
    .
  39. ^ Weller et al. 2015, p.22

Sources

External links
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