Diapiric replenishment of magma chambers and triggering of volcanism in the Taupo Volcanic Zone, New Zealand

Hodder, Peter

doi:10.1016/0009-2541(83)90059-1

Cited by 6 publications

(4 citation statements)

References 28 publications

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“…This contemporaneity is interpreted as representing a form of "tectonic throttling" (e.g. Lanphere These findings corroborate previously reported contemporaneity between the Tongariro-Ruapehu-Taupō area that led to suggestions that tectonics may have synchronised activity at these volcanoes, as inferred from voluminous interfingered andesitic and rhyolitic tephras erupted in the early Holocene (Kohn and Topping, 1978;Hodder, 1983;Nairn et al, 1998;Nakagawa et al, 1998). Hobden (1997) and Cole (1978Cole ( , 1979.…”

Section: Magmatism Volcanism and Tectonicssupporting

confidence: 87%

“…Titanomagnetites in these younger Taupō tephras have lower V/Cr ratios of ~5-10 and Ni and Co concentrations of ~10-100 ppm (Kohn and Topping, 1978). A separate study by Hodder (1983) showed that titanomagnetite Co/Mn ratios decreased from ~0.080 to ~0.040 (Tongariro and/or Ruapehu) and from ~0.020 to ~0.005 (Taupō)…”

Section: Links Between Regional Andesitic and Rhyolitic Activity In T...mentioning

confidence: 92%

“…Uncanny contemporaneity has been suggested for relatively large eruptions (Nakagawa et al, 1998;Nairn et al, 1998) and contemporaneous compositional variation (Kohn and Topping, 1978;Hodder, 1983) between each of these volcanoes during the Holocene. To build on this, new results from Tongariro (this study) and a recently improved chronostratigraphic framework for Ruapehu (Conway et al, 2016;Townsend et al, 2017) are used to examine evidence for potentially synchronised magmatism for a greater interval from ~230 ka to present.…”

Section: Links Between Regional Andesitic and Rhyolitic Activity In T...mentioning

confidence: 99%

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The volcanic and magmatic evolution of Tongariro volcano, New Zealand

Pure¹

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<p>Detailed mapping studies of Quaternary stratovolcanoes provide critical frameworks for examining the long-term evolution of magmatic systems and volcanic behaviour. For stratovolcanoes that have experienced glaciation, edifice-forming products also act as climate-proxies from which ice thicknesses can be inferred at specific points in time. One such volcano is Tongariro, which is located in the southern Taupō Volcanic Zone of New Zealand’s North Island. This study presents the results of new detailed mapping, geochronological and geochemical investigations on edifice-forming materials to reconstruct Tongariro’s volcanic and magmatic history which address the following questions: (1) Does ice coverage on stratovolcanoes influence eruptive rates and behaviour (or record completeness)? (2) What is the relationship between magmatism, its expression (i.e. volcanism) and external but related processes such as tectonics? (3) How are intermediate-composition magmas assembled and what controls their diversity? (4) What are the relative proportions of mantle-derived and crust-derived materials in intermediate composition arc magmas? (5) Do genetic relationships exist between andesite and rhyolite magmas in arc settings? Samples from 250 new field localities in under-examined areas of Tongariro were analysed for major oxide, trace element and Sr-Nd-Pb isotope compositions. Analyses were performed on whole-rock, groundmass and xenolith samples. The stratigraphic framework for these geochemical data was established from field observations and 29 new 40Ar/39Ar age determinations, which were synthesised with volume estimates and petrographic observations for all Tongariro map units. Mapping results divide Tongariro into 36 distinct map units (at their greatest level of subdivision) which were organised into formations and constituent members. New 40Ar/39Ar age determinations reveal continuous eruptive activity at Tongariro from at least 230 ka to present, including during glacial periods. This adds to the discovery of an inlier of old basaltic-andesite (512 ± 59 ka) on Tongariro’s NW sector that has an unclear source vent. Hornblende-phyric andesite boulders, mapped into the Tupuna Formation (new), yield the oldest 40Ar/39Ar age determination (304 ± 11 ka) for materials confidently attributed to Tongariro. Tupuna Formation andesites are correlated with Turakina Formation debris flows that were deposited between 349 to 309 ka in the Wanganui Basin, ~100 km south of Tongariro, which indicates that Ruapehu did not exist at this time, at least not in its current form. Tongariro has a total edifice volume of ~90 km3, 19 km3 of which is represented by exposed mapped units. The total ringplain volume immediately adjacent to Tongariro contains ~60 km3 of material. The volume of exposed glacial deposits are no more than 1 km3. During periods of major ice coverage, edifice-building rates on Tongariro were only 17-21 % of edifice-building rates during warmer climatic periods. Because shifts in edifice-building rates do not coincide with changes in erupted compositions, differences in edifice-building rates reflect a preservation bias. Materials erupted during glacial periods were emplaced onto ice masses and conveyed to the ringplain as debris, which explains reduced preservation rates at these times. MgO concentrations in Tongariro stratigraphic units with ages between 230 and 0 ka display successive and irregular cyclicity that occurs over ~10-70 kyr intervals, which reflect episodes of enhanced mafic magma replenishment. During these cycles, more rapid (≤10 kyr) increases in MgO concentrations to ≥5-9 wt% are followed by gradual declines to ~2-5 wt%, with maxima at ~230, ~160, ~117, ~88, ~56, ~35, ~17.5 ka and during the Holocene. Contemporaneous variations in Tongariro and Ruapehu magma compositions (e.g. MgO, Rb/Sr, Sr-Nd-Pb isotope ratios) for the 200-0 ka period coincide with reported zircon growth model-ages in Taupō magmas. This contemporaneity reflects regional tectonic processes that have externally regulated and synchronised the timings of elevated mafic replenishment episodes versus periods of prolonged crustal residence at each of these volcanoes. Isotopic Sr-Nd-Pb data from metasedimentary xenoliths, groundmass separates and whole-rock samples indicate that two or three separate metasedimentary terranes (in the upper 15 km of the crust) were assimilated into Tongariro magmas. These are the Kaweka terrane and the Waipapa or Pahau terranes (or both). Subhorizontal juxtapositioning of these terranes is indicated by the coexistence of multiple terranes in the same eruptive units. Paired whole-rock and groundmass (interstitial melt) samples have effectively equal Sr-Nd-Pb isotope ratios for the complete range of Tongariro compositions. Despite intra-crystal isotopic heterogeneities that are likely widespread, the new data show that crystal fractionation and assimilation occur in approximately equal balance for essentially all Tongariro eruptives. Assimilated country rock accounts for 22-31 wt% of the average Tongariro magma. Initial evolution from a Kakuki basalt-type to a Tongariro Te Rongo Member basaltic-andesite reflects the addition of 17 % assimilated metasedimentary basement with a mass assimilation rate/mass crystal fractionation rate ratio—a.k.a. ‘r value’ of 1.8-3.5. Subsequent evolution from a Te Rongo Member basaltic-andesite to other Tongariro eruptive compositions represents 5-14 % more assimilated crust (r values of ~0.1-1.0). Magma evolution from high (>1) to lower (0.1-1.0) r values can explain the dearth of andesitic melt inclusions in (bulk) andesite magmas observed globally. High relative assimilation rates characterise rapid evolution from basalt to basaltic-andesite bulk compositions which contain andesitic interstitial melts. Thus, andesitic melt inclusions have a reduced chance of being preserved in crystals which can explain their low representation in global datasets.</p>

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Section: Magmatism Volcanism and Tectonicssupporting

confidence: 87%

Section: Links Between Regional Andesitic and Rhyolitic Activity In T...mentioning

confidence: 92%

Section: Links Between Regional Andesitic and Rhyolitic Activity In T...mentioning

confidence: 99%

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The volcanic and magmatic evolution of Tongariro volcano, New Zealand

Pure¹

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“…These contemporaneous shifts in tephra compositions suggested that magmatic variations between separate volcanoes (and unconnected magma systems) could be synchronised by an external, common influence. Subsequent studies by Hodder (1983) and Nairn et al (1998) have further supported this hypothesis. Here, we propose that contemporaneous fluctuations in magmatic activity at Tongariro, Ruapehu and Taupō are a long-term feature over their > 200 kyr histories.…”

Section: Contemporaneous Magmatic Events At Tongariro Ruapehu and Tau...mentioning

confidence: 83%

The compositional diversity and temporal evolution of an active andesitic arc stratovolcano: Tongariro, Taupō Volcanic Zone, New Zealand

Pure

Wilson

Charlier

et al. 2023

Contrib Mineral Petrol

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New geochemical data, including Sr–Nd–Pb isotopes for whole-rock and groundmass samples, are reported for edifice-forming eruptives at Tongariro volcano, New Zealand, which span its ~ 350 ka to late Holocene history. Tongariro eruptives are medium-K basaltic-andesites to dacites (53.0–66.2 wt% SiO2) that evolved via assimilation-fractional crystallisation (AFC) processes partly or mostly in the uppermost 15 km of the crust. When ordered chronologically using a high-resolution 40Ar/39Ar-dated eruptive stratigraphy, the compositional data show systematic 10–130 kyr cycles. Mafic replenishment events inferred from MgO values occurred at ~ 230, ~ 151, ~ 88 and ~ 56 ka and in the late Holocene, with high-MgO flank vents erupting at ~ 160, ~ 117, ~ 35 and ~ 17.5 ka. Cycles in Sm/Nd, 87Sr/86Sr, 143Nd/144Nd and Pb isotopic ratios, which are decoupled from MgO, K2O and Rb/Sr cycles, indicate periods of prolonged crustal residence of magmas from ~ 230 to ~ 100 ka and ~ 95 to ~ 30 ka. AFC modelling shows that intermediate and silicic melt compositions, with r-values between 0.1 and 1, are needed to reproduce Tongariro compositional arrays. AFC models also indicate that ~ 20% of the average Tongariro magma comprises assimilated (meta)sedimentary basement material. Locally, Tongariro and adjacent Ruapehu volcanoes attain their most crust-like 87Sr/86Sr and 143Nd/144Nd compositions at ~ 100 and ~ 30 ka, paralleling with zircon model-age crystallisation modes at the rhyolitic Taupō volcano ~ 50 km to the NNE. These coincidences suggest that the timing and tempo of magma assembly processes at all three volcanoes were contemporaneous and may have been tectonically influenced since at least 200 ka.

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Depth of origin of basalts inferred from Ti/V ratios and a comparison with the K2O-depth relationship for island-arc volcanics

Hodder

1985

Chemical Geology

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Diapiric replenishment of magma chambers and triggering of volcanism in the Taupo Volcanic Zone, New Zealand

Cited by 6 publications

References 28 publications

The volcanic and magmatic evolution of Tongariro volcano, New Zealand

The volcanic and magmatic evolution of Tongariro volcano, New Zealand

The compositional diversity and temporal evolution of an active andesitic arc stratovolcano: Tongariro, Taupō Volcanic Zone, New Zealand

Depth of origin of basalts inferred from Ti/V ratios and a comparison with the K2O-depth relationship for island-arc volcanics

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