Pouakai Range

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Pouakai Range
Pouakai Range, New Zealand, February 2016 05.JPG
The Pouakai Range viewed from Mount Taranaki, with the Kaitake Range in the background
Highest point
PeakPouakai
Elevation 1,395 m (4,577 ft)
Coordinates 39°14′17″S174°00′51″E / 39.23806°S 174.01417°E / -39.23806; 174.01417
Geography
Pouakai Range
Pouakai andesite (red shading) in centre of map. To its south-south-east is the younger and presently larger in andesitic direct deposits volcano of Mount Taranaki. The surrounding debris and lahar fields are not shown but include the green forested area on the map. To its north west are the older volcanoes of the small cone of Pukeiti, then the Kaitake. Clicking on the map enlarges it, and enables panning and mouseover of volcano name/wikilink and ages before present. Key for the volcanics that are shown with panning is:    basalt (shades of brown/orange),    monogenetic basalts,
  undifferentiated basalts of the Tangihua Complex in Northland Allochthon,
  arc basalts,  arc ring basalts,
   dacite,
   andesite (shades of red),   basaltic andesite,
   rhyolite, (ignimbrite is lighter shades of violet),
and   plutonic. White shading is selected caldera features.
Location North Island, New Zealand
Geology
Age of rock 250 ka, [1] Pleistocene
Type of rock Andesite
Volcanic belt Taranaki Volcanic Lineament
Last eruption 210 ka

The Pouakai Range is an eroded and heavily vegetated stratovolcano in the North Island of New Zealand, located northwest of Mount Taranaki. It consists of the remains of a collapsed Pleistocene stratovolcano. The range is surrounded by a ring plain of lahar deposits from a massive collapse that has been dated as roughly 250,000 years old. [2]

Contents

The region has been reshaped more recently after each cone collapse from Mount Taranaki. [3]

Geology

The Pouakai Range volcano is situated in the Taranaki Basin and is part of the Taranaki Volcanic Lineament which has had a 30 mm/yr north to south migration over the last 1.75 million years. [1] Present-day seismicity and stress directions in eastern Taranaki are consistent with back-arc extension processes. [1] The Taranaki Volcanic Lineament members as they decrease in age from northwest to southeast are: [1]

  1. Paritutu, and the Sugar Loaf Islands from 1.75 Ma
  2. Kaitake from 575 ka
  3. Pouakai 210–250 ka
  4. Mount Taranaki <200 ka

Volcanic activity

"After the extinction of the Kaitake center, eruptions broke out at Pouakai 6 miles south-east of Kaitake. Activity from this center continued over a long period of ring-plain formation, a period of marine erosion during which volcanic activity decreased, and part way through another period of ring-plain building, before activity broke out from the next center." [4] It can be postulated that that all volcanoes in the Taranaki Volcanic Lineament have had a similar potential for instability and were stratovolcanoes of similar size and shape to the present Mount Taranaki between major collapse events given their debris plains. They may well have had major collapse cycles similar to that presently shown by Mount Taranaki which is a potential maximum size of collapse of 7.9 km3 (1.9 cu mi) every 30,000 to 35,000 years. [1]

Nearby volcanoes

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The volcanic activity in the South Island of New Zealand terminated 5 million years ago as the more northern parts of the North Island became extremely volcanically active. The South Islands surface geology reflects the uplift of the Pacific Plate as it collides with the Indo-Australian Plate along the Alpine Fault over the last 12 million years and the termination of subduction, about 100 to 105 million years ago. There is a very small chance of reactivation of volcanism in the Dunedin Volcano. This chance is made slightly higher by the observation that Southland's Solander Islands / Hautere just off the coast of the South Island were active as recently as 50,000 years old, and on a larger scale 150,000 years old.

References

  1. 1 2 3 4 5 Cronin, Shane J.; Zernack, Anke V.; Ukstins, Ingrid A.; Turner, Michael B.; Torres-Orozco, Rafael; Stewart, Robert B.; Smith, Ian E. M.; Procter, Jonathan N.; Price, Richard; Platz, Thomas; Petterson, Michael; Neall, Vince E.; McDonald, Garry S.; Lerner, Geoffrey A.; Damaschcke, Magret; Bebbington, Mark S. (2021). "The geological history and hazards of a long-lived stratovolcano, Mt. Taranaki, New Zealand". New Zealand Journal of Geology and Geophysics. 64 (2–3): 456–478. doi: 10.1080/00288306.2021.1895231 . S2CID   233700970.
  2. "Pouakai". Global Volcanism Program . Smithsonian Institution . Retrieved 11 June 2020.
  3. "A line of volcanoes - the birth of Taranaki". Puke Ariki. 12 April 2012 via YouTube.
  4. Grant-Taylor, T. L. (21 December 2011). "Volcanic history of Western Taranaki". New Zealand Journal of Geology and Geophysics. 7: 78–86. doi: 10.1080/00288306.1964.10420158 .