View source for Earth:Mangakino caldera complex

{{Short description|A volcanic caldera in New Zealand}}
{{Infobox mountain
| name = Mangakino Caldera
| photo = Mangakino.Caldera.Rift.Zone.North.Island.NZ.jpg
| photo_caption = Approximate extent of ignimbrite sheets from Kidnappers (yellow) and Rocky Hill eruptions (orange) as determined from land drill cores sampling. The Kidnappers ignimbrite has been reported in some cores from just beyond the boundaries shown and this map only tries to show where there was full coverage of the then existing landforms and present land surface to convey an idea of the minimal total biosphere disruption.<ref name="Cooper2016">{{harvnb|Cooper|Wilson|Millet|Baker|2016}}</ref><ref name="Spinks2005"/><ref name="Pittari2021"/>
| map=North Island
| elevation_m =
| elevation_ref = 
| prominence =
| location = North Island, New Zealand
| coordinates ={{coord|38|23|S|175|47|E|display=inline,title}}
| topo = 
| type = [[Earth:Caldera|Caldera]]
| age = {{Geological range|1.6|0.93|prefix=[[Earth:Pleistocene|Pleistocene]] (|ref=)<ref name="Pittari2021"/>}}
| length = {{convert|30|km|abbr=on}}<ref name="Pittari2021"/>
| width =  {{convert|15|km|abbr=on}}<ref name="Pittari2021"/>
| volcanic_arc/belt = [[Earth:Taupo Volcanic Zone|Taupo Volcanic Zone]]
| last_eruption = 900,000 years ago<ref name="Pittari2021"/>
}}
[[File:Maroa.Caldera.Rift.Zone.North.Island.NZ.jpg|thumb|left|alt= Approximate size and location of Mangakino caldera complex|Mangakino Caldera north of [[Earth:Lake Taupō|Lake Taupō]] in the old Taupō Rift (yellow shading). Also shown to its east are the Whakamaru caldera, the more recent Maroa Caldera contained within it and the Ohakuri Caldera which had a paired eruption with the Rotorua Caldera. Also shown is the modern Taupō Rift (red shading), Hauraki Rift (purple shading) and landmarks of Lake Taupō and Lake Rotorua]]
The '''Mangakino caldera complex''' (other names are '''Mangakino volcanic center''', '''Mangakino Caldera''') is the westernmost and one of oldest extinct rhyolitic [[Earth:Caldera|caldera]] volcanoes in the [[Earth:Taupō Volcanic Zone|Taupō Volcanic Zone]] of [[Earth:New Zealand|New Zealand]]'s North Island.<ref name="Krippner1998">{{Cite journal |doi=10.1080/00288306.1998.9514803 |last1=Krippner |first1=Stephen J. P. |last2=Briggs |first2=Roger M. |last3=Wilson |first3=Colin J. N. |last4=Cole |first4=James W. |year=1998 |title=Petrography and geochemistry of lithic fragments in ignimbrites from the Mangakino Volcanic Centre: implications for the composition of the subvolcanic crust in western Taupo Volcanic Zone, New Zealand |journal=New Zealand Journal of Geology and Geophysics |volume=41 |pages=187–199 |issue=2 |doi-access=free }}</ref>  It produced about a million years ago (1 Ma) in the Kidnappers eruption of {{convert|1200|km3|cumi|1|sp=us|abbr=on}}, the most widespread ignimbrite deposits on Earth being over {{convert|45000|km2|abbr=on}}<ref name="Cooper2016"/> and was closely followed in time by the smaller {{convert|200|km3|cumi|1|sp=us|abbr=on}} Rocky Hill eruption.<ref name="Cooper2012">{{cite journal|last= Cooper|first= G.F. |author2=C. J. Wilson|author3=J. A. Baker |author4=M. Millet |year= 2012 |title= Rejuvenation and Repeated Eruption of a 1.0 Ma Supervolcanic System at Mangakino Caldera, Taupo Volcanic Zone, New Zealand  |journal= AGU Fall Meeting Abstracts |volume= 2012 |bibcode= 2012AGUFM.V31C2797C | url= https://ui.adsabs.harvard.edu/abs/2012AGUFM.V31C2797C/abstract |accessdate= 2022-05-15 }}</ref> The Kidnappers eruption had a estimated VEI of 8 and has been assigned a total eruption volume (not just tephra) of {{convert|2760|km3|cumi|1|sp=us|abbr=on}}.

However this was only in its most recent caldera forming phase from 1.21 to 0.91 million years ago as it had its earliest caldera generating phase from 1.62 to 1.51 million years ago.<ref name="Cooper2016"/> There are at least 11 major historic eruptions assigned to this complex.<ref>{{cite web |title=Mangakino |url=http://www.bgs.ac.uk/vogripa/searchVOGRIPA.cfc?method=detail&id=950 |publisher=VOGRIPA |access-date=9 December 2018 |archive-url=https://web.archive.org/web/20181209124038/http://www.bgs.ac.uk/vogripa/searchVOGRIPA.cfc?method=detail&id=950 |archive-date=9 December 2018 |url-status=live }}</ref> At least 5 of these contributed significant welded ignimbrite deposits that represent major pyroclastic events in the central North Island.<ref name="Spinks2005">{{Cite web|title= Rift Architecture and Caldera Volcanism in the Taupo Volcanic Zone, New Zealand |url=https://ir.canterbury.ac.nz/handle/10092/4944| year=2005 |last1=Spinks |first1=Karl D. }}</ref> Ongatiti Ignimbrite (Hinuera Stone) from a 7 VEI event,{{snf|Yousef Zadeh|2020|pp=ii}} about 1.3 million years ago, has now been found over a wider area and several meter thick tephra deposits from the eruption exist on drill samples from both [[Place:Auckland|Auckland]] and [[Place:Wellington|Wellington]].{{snf|Yousef Zadeh|2020|p=38}}<ref name="Zadeh2023">{{harvnb|Yousef Zadeh|Pittari|Lowe|Danišík|2023|loc=Conclusions}}</ref>

The earliest characterised eruptives from the complex are [[Earth:Andesite|andesitic]]<ref name="Zadeh2020T">{{Harvnb|Yousef Zadeh|2020|loc=table 1.1}}</ref> and the mechanism of transition from this to the more explosive later [[Earth:Rhyolite|rhyolitic]] eruptions is related to increased heat flow from the [[Biology:Magma|magma]] sources.<ref name="Zadeh2020P9">{{Harvnb|Yousef Zadeh|2020|p=9}}</ref>

Later many of these deposits were covered over by deposits from other eruptive centres such as those of the [[Earth:Oruanui eruption|Oruanui eruption]].

The caldera can be defined by gravitational measurements as {{convert|30|km|abbr=on}} by {{convert|15|km|abbr=on}} and its "basement" floor is at least {{convert|4|km|abbr=on}} below the present ground surface.<ref name="Pittari2021">{{harvnb|Pittari|Prentice|McLeod|Yousef Zadeh|2021}}</ref>  
{| class="wikitable"
|+ Assigned eruptions for the Mangakino Caldera (note Unit F not definitely assigned)<ref name="Pittari2021"/><ref name="Zadeh2020T"/>
|-
! Formations !! Layer names !! Age range estimate by various methods<br />(if only one method ± error) !! Eruptive volume
|-
| Marshall ||Unit I (Marshall A and B) Ignimbrite<br />Unit H (Kaahu) Ignimbrite<br />Unit G|| 0.95 ± 0.03 Ma ||
|-
| Whakaahu || Rhyolite dome  || 1.02 ± 0.02 Ma ||
|-
| Raepahu<br/>(Potaka Tephra)<ref name="Cooper2016"/> || Rocky Hill Ignimbrite<br /> Kidnappers Unit E Ignimbrite and fall deposit|| 0.95 to 1.15 Ma<br /><br /> 0.93 to 1.07 Ma || {{convert|200|km3}}<br /> >{{convert|1200|km3}}
|-
|  Mangaokewa ||Ahuroa Ignimbrite<br /> Unit D Ignimbrite and fall deposit|| 1.16 to 1.33 Ma<br /> 1.20 ± 0.04 Ma ||
|-
| Ongatiti|| Ongatiti Ignimbrite (Oparau tephra, K12a Kauroa Ash Formation, K12){{snf|Yousef Zadeh|2020|p=150}}<br /> Tumai Rd dome|| 1.37 ± 0.04 Ma (1.31 ± 0.09 Ma, 1.38 ± 0.06 Ma, 1.38 ± 0.05 Ma){{snf|Yousef Zadeh|Pittari|Lowe|Danišík|2023|loc=Compilation of published ages and new (Usingle bondTh)/He data}}<br>1.16 to 1.34 Ma<br /> 1.27 ± 0.05 Ma || >{{convert|1000|km3}} [[Earth:Dense-rock equivalent|DRE]]<ref name="Zadeh2023"/>
|-
| Pouakani  || Unit C Ignimbrite || 1.68 ± 0.07 Ma (This age inconsistent with position) ||
|-
| Tolley || Unit B Ignimbrite || 1.53 ± 0.04 Ma ||
|-
| Ngaroma || Ngaroma  (Unit A) Ignimbrite || 1.31 to 1.6 Ma ||
|-
| Link  (source unknown)|| Unit F Ignimbrite || 1.60 ± 0.09 Ma ||
|}
{{maplink|frame=yes
|frame-align=center
|text=Map of selected surface volcanic deposits centered to include all the present surface Mangakino caldera ignimbrites. Tephra and buried ignimbrite from these eruptions were even more widespread as illustrated elsewhere on this page. The present surface ignimbrite is various light violet shades which are identical for any single source, but other eruptions breakup the mutual ignimbrite sheets. Thus clicking on the map enlarges it, and enables panning and mouseover of volcanic deposits name/wikilink and ages before present for wider volcanic context.  The key to the shading of other volcanics that are shown (active in last million years odd) with panning is rhyolite - violet, dacite - purple,  [[Earth:Basalt|basalt]] - brown, monogenic basalts - dark brown, undifferentiated basalts of the Tangihua Complex in Northland Allochthon - light brown, arc basalts - deep orange brown, arc ring basalts -orange brown, [[Earth:Andesite|andesite]] - red ,  basaltic andesite`- light red, and plutonic - gray. White shading has been used for postulated calderas (usually subsurface now).  
|raw={{Wikipedia:Map data/Northern North Island Volcanics}}
|frame-width=500 
|frame-height=520 
|frame-lat=-38.25
|frame-long=175.57
|icon=no
|zoom=9
}}

==Geological understanding==
That there was a separate Mangakino volcanic complex was first understood in 1965,<ref name="Zadeh2020P8">{{Harvnb|Yousef Zadeh|2020|p=8}}</ref> and a caldera structure by gravity studies in 1982.<ref name="Zadeh2020P8"/> The recognition was impaired mainly because of erosion produced discontinuities, burying by later volcanic deposits or overburden displacement in later caldera formation. The extent of eastern ignimbrite deposits from the early Ongatiti event is still unknown  and even the eastern caldera boundary is ill defined due to the very disruptive margins of the new Taupō Rift to the east of the complex. At Tokoroa to the complexes north,  Ongatiti ignimibrite is for example found at a depth of between {{convert|392| to |457|m|abbr=on}}.<ref>{{cite book|last1=Houghton |first1=B |last2= Wilson |first2=C |last3= Stern |first3= T |year=1987|title=New Zealand Geological Survey Record: Ignimbrite stratigraphy of a 457 m deep drillhole near Tokoroa|volume= 20|pages= 51–53| publisher=New Zealand Geological Survey, Lower Hutt |editor=J Begg |issn=0112-465X}}</ref><ref name="Zadeh2020P12">{{Harvnb|Yousef Zadeh|2020|p=12}}</ref> 

What are now termed ignimbrites and manifest as prominent surface deposits, far from the complex, were recognised by Ferdinand von Hochstetter in his 1859 maps.<ref name="Zadeh2020P11">{{Harvnb|Yousef Zadeh|2020|p=11}}</ref> From the early 1960s the various ignimbrites from the complex were assigned names and studied in more detail.<ref name="Zadeh2020P11"/>  Colin Wilson first defined the Mangakino caldera complex in 1964 and went on to improve the understanding of its ignimbrite distribution and stratigraphy.<ref name="Zadeh2020P11"/> Reliable age data became available from the 1990s.<ref name="Zadeh2020P11"/> It was in the late 1990s that it first became recognised that the size of the eruptions had been underestimated,<ref name="Zadeh2020P12"/> but not until 2016–17 that proof of [[Earth:Supervolcano|super eruptions]] was presented.<ref name="Cooper2016"/>

The Mangakino caldera eruptives are definitely assignable to the [[Earth:Taupō Volcanic Zone|Taupō Volcanic Zone]] but are to the west of the currently most active portion of the Taupō Rift.<ref name="Cooper2016"/> To its north the transition between the north-western Taupō Rift and the [[Earth:Coromandel Volcanic Zone|Coromandel Volcanic Zone]] via the [[Earth:Tauranga Volcanic Centre|Tauranga Volcanic Centre]] and its 2.1 million year old Waiteariki Formation are subject to on going study.<ref name=Prentice2022>{{cite journal|first1=Marlena |last1=Prentice |first2= Adrian |last2=Pittari |first3= David J. |last3=Lowe |first4= Geoff |last4=Kilgour |first5= Peter J.J. |last5=Kamp |first6= Miriam | last6=Namaliu |title=Linking proximal ignimbrites and coeval distal tephra deposits to establish a record of voluminous Early Quaternary (2.4–1.9 Ma) volcanism of the Tauranga Volcanic Centre, New Zealand |journal=Journal of Volcanology and Geothermal Research |volume =429 |year=2022 |issue=107595 |page=107595 |issn=0377-0273 |doi=10.1016/j.jvolgeores.2022.107595 |s2cid=249264293 |url=https://www.sciencedirect.com/science/article/pii/S0377027322001263 }}</ref>

==References==
{{Reflist|33em}}
;Sources
{{Refbegin}}
*{{cite journal|title=Generation and Rejuvenation of a Supervolcanic Magmatic System: a Case Study from Mangakino Volcanic Centre, New Zealand |year=2016 |journal=Journal of Petrology |volume=57 |issue=6 |pages=1135–1170 |doi=10.1093/petrology/egw035 |first1=George F |last1=Cooper|first2=Colin |last2=Wilson |first3=Marc-Alban |last3=Millet |first4=Joel |last4= Baker |url=https://www.researchgate.net/publication/305343015 |doi-access=free }}<!-- {{harvnb|Cooper|Wilson|Millet|Baker|2016}} -->
*{{cite thesis|last=Yousef Zadeh|first= E.|year=2020|title= Eruption and emplacement of the 1.3-Ma Ongatiti Ignimbrite, New Zealand: Regional pathways, particle processes, and pumice evolution associated with a large-volume pyroclastic flow deposit|type=PhD| publisher=The University of Waikato, Hamilton, New Zealand|hdl= 10289/14063| url=https://hdl.handle.net/10289/14063}}<!-- {{snf|Yousef Zadeh|2020}} -->
*{{cite journal|first1=Adrian |last1=Pittari |first2=Marlena L. |last2=Prentice |first3= Oliver E. |last3=McLeod |first4= Elham |last4=Yousef Zadeh |first5= Peter J. J. |last5=Kamp |first6= Martin |last6=Danišík |first7=Kirsty A. |last7=Vincent |year=2021 |title= Inception of the modern North Island (New Zealand) volcanic setting: spatio-temporal patterns of volcanism between 3.0 and 0.9 Ma |journal= New Zealand Journal of Geology and Geophysics |volume=64 |issue=2–3 |pages= 250–272 | doi=10.1080/00288306.2021.1915343 |s2cid=235736318 |url=https://fl-nzgs-media.s3.amazonaws.com/uploads/2021/08/Ref.6C-c_North-Island-NZ-VolcanicSettingBetween3.00.9MaPittari-et-al.-2021_.pdf }}<!-- {{harvnb|Pittari|Prentice|McLeod|Yousef Zadeh|2021}} -->
*{{cite journal|first1=Elham |last1=Yousef Zadeh|first2= Adrian |last2=Pittari|first3= David J. |last3=Lowe|first4= Martin |last4=Danišík|title=Mobility and emplacement of an ancient, large-volume pyroclastic flow, Ongatiti Ignimbrite, North Island, New Zealand|journal=Journal of Volcanology and Geothermal Research|volume= 440 |year=2023|issue=107853 |page=107853 |issn=0377-0273 |doi=10.1016/j.jvolgeores.2023.107853 |s2cid=259551526 |url=https://www.sciencedirect.com/science/article/pii/S0377027323001105 }}
<!-- {{harvnb|Yousef Zadeh|Pittari|Lowe|Danišík|2023}} -->
{{Refend}}

==External links==
*{{cite gvp|vn=241818|name=Mangakino}}

[[Category:Supervolcanoes]]

{{Sourceattribution|Mangakino caldera complex}}