Processes and time scales of dacite magma assembly and eruption at Tauhara volcano, Taupo Volcanic Zone, New Zealand

Millet, Marc-Alban; Tutt, Chelsea M.; Handler, Monica R.; Baker, Joel A.

doi:10.1002/2013gc005016

Cited by 23 publications

(24 citation statements)

References 71 publications

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“…A timescale of days to weeks between mixing and eruption is comparable to the short pre-eruptive mixing timescales calculated at Ceboruco, Quizapu, Nea Kamini and Mount Unzen volcanoes (days to months; Nakamura, 1995;Chertkoff and Gardner, 2004;Ruprecht and Cooper, 2012;Martin et al, 2008). Other mixed systems at Trident, Taupo and Volcan San Pedro, give longer timescales (months to decades; Coombs et al 2000;Costa and Chakraborty, 2004;Millet et al, 2014). Our results imply a relatively short period between the assembly of the SSH magmas and their ascent and eruption at the surface.…”

Section: Timing Of Mixing Eventssupporting

confidence: 78%

“…In addition, there is evidence that tectonics can strongly control the composition of magmas. For instance, at the Taupo volcanic zone basaltic volcanism occurs at the intersection between major faults and caldera boundaries (Cole et al, 1990;Millet et al 2014) whereas, more intermediate magmatism occurs in areas which have experienced less crustal extension (Allan et al 2013 ;Millet et al 2014), following the recharge filtering process. Transtensional faults in the neighbouring island to Montserrat, Guadeloupe, which lies along the same en echelon fault system, are thought to control the location of volcanism and may be the cause for the frequent sector collapses on the island (Mathieu et al, 2011).…”

Section: Tectonic Control For the Eruption Of Basaltsmentioning

confidence: 99%

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Origin of Basalts by Hybridization in Andesite-dominated Arcs

Cassidy

Edmonds

Watt

et al. 2015

Journal of Petrology

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Mafic magmas are common in subduction zone settings, yet their high density restricts their ascent to the surface. Once stalled in the crust, these magmas may differentiate, assimilate crust and other melts and mushes to produce hybridised intermediate magmas. The Soufriere Hills Volcano on Montserrat is a 'type locality' for these hybridisation processes and yet, just 3 km south of the crater, voluminous basalts have erupted from the South Soufriere Hills volcano within the same time period as the Soufriere Hills Volcano was erupting hybrid andesites (131 -128 ka). Basaltic South Soufriere Hills magmas have 48 -53 wt% SiO2 and 4 -6 wt% MgO. They were hot (970 -1160 °C), volatile-rich (melt inclusions contain up to 6.2 wt% H2O) and were stored at 8 -13 km prior to eruption (based on olivine and pyroxene-hosted melt inclusion volatile geochemistry). Melt inclusions do not preserve basaltic liquids: they are andesitic to rhyolitic in composition, related to one another by a line of descent controlled by simple closed-system fractionation. Whole rock compositions, however, are best described by a hybridisation model involving "back"-mixing of andesitic to rhyolitic melts with mafic crystal phases such as magnetite, olivine, orthopyroxene and clinopyroxene. Phenocryst zoning illustrates repeated mixing events between evolved melts and mafic phenocrysts, which, when coupled with the heterogeneity of crystal compositions, strongly suggests that although the bulk composition is basalt (containing Fo80 olivine), they were assembled from disparate ingredients, likely derived from mafic crystal mushes and more evolved melt lenses of variable composition. The mixing events occur days to weeks prior to eruption. We propose that the South Soufriere Hills basaltic magmas, with their higher bulk density over andesites from neighbouring volcanoes, ultimately may have been eruptible owing to both the transtensional tectonics imposed by offshore grabens (related to the oblique subduction of the Lesser Antilles) and to surface unloading caused by large scale edifice collapse. Our observations support the idea that compositional changes in arcs might reflect not only changes in source compositions, but also effects caused by patterns in crustal strain and tectonics.

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Section: Timing Of Mixing Eventssupporting

confidence: 78%

Section: Tectonic Control For the Eruption Of Basaltsmentioning

confidence: 99%

Origin of Basalts by Hybridization in Andesite-dominated Arcs

Cassidy

Edmonds

Watt

et al. 2015

Journal of Petrology

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“…2-4 wt% H 2 O in Keith et al, 2018). , and more coarse-grained aggregates (~1-2 mm) of plagioclase, clinopyroxene, and Fe-Ti oxide indicate mixing of a more mafic with a more silicic magma to produce the Brothers volcano dacite, which is consistent with observations of dacite from other volcanic arc systems (e.g., Grove et al, 2005;Millet et al, 2014).…”

Section: Discussionsupporting

confidence: 85%

Site U1531

Ronde¹,

Humphris²,

Höfig³

et al. 2019

Brothers Arc Flux

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Background and objectives 3 Operations 6 Igneous petrology and volcanology 9 Alteration 10 Structural geology 10 Geochemistry 11 Paleomagnetism 13 Physical properties 15 Downhole measurements 15 Microbiology 16 References C.E.J. de Ronde et al. Site U1531 IODP Proceedings 2 V o l u m e 3 7 6 Hole U1531E. We could not advance any deeper because the TDCS core barrel got stuck in the bottom-hole assembly (BHA) and could not be retrieved. After the TDCS test, we cored with the RCB system from 17.9 to 39.6 mbsf and recovered only 0.8 m (4%). At this point, the blower motor in the top drive failed. We decided not to repair it at this time because of our remaining scientific priorities and the impending end of the expedition. Our final operation at Site U1531 consisted of a downhole temperature measurement with the Elevated Borehole Temperature Sensor (ETBS) memory tool. The tool recorded a maximum temperature of ~5°C at 20 mbsf. In total, 264.25 h, or 11.01 days, were spent at Site U1531. Principal results Igneous petrology and volcanology At Site U1531, one igneous unit was observed in Holes U1531A (0-1.14 mbsf), U1531B (0-21.97 mbsf), U1531C (0-23.75 mbsf), and U1531E (17.90-34.95 mbsf) as well as in several "ghost cores" from Hole U1531E. Igneous Unit 1 consists of unaltered to slightly altered plagioclase-pyroxene-phyric dacite lava intercalated with unconsolidated ash, ash with lapilli, and lapilli tephra with ash. The moderately to highly vesicular dacite lava contains glomerocrysts and phenocrysts of plagioclase, orthopyroxene, and clinopyroxene and Fe-Ti oxides in a cryptocrystalline and hypocrystalline groundmass. Volcaniclastic material is mainly composed of unaltered dacite clasts, crystals, and subordinate lithic components. The composition of the dacite lava and pyroclastic rocks from Site U1531 is similar to that of dacite cored in the upper sections at Sites U1527 and U1529. Alteration One alteration type was identified at Site U1531 based on an alteration assemblage identified using a combination of macroscopic and microscopic descriptions and X-ray diffraction (XRD) analyses. Alteration Type I is classified as slightly altered and has an alteration mineral assemblage of smectite, Fe oxyhydroxide, zeolite, pyrite, and rare native sulfur. Alteration occurs as infilling and lining of vesicles and smectite replacing the glassy matrix.

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“…Given the parameters and scenarios outlined above, we consider it most plausible that the dacites were sourced from a region spatially overlapping with the base of the protoOruanui mush system, at depths of ≥~8 km (Allan 2013), similar to that documented by Millet et al (2014) for dacites erupted from nearby Tauhara volcano (Fig. 1a).…”

Section: Origin and Significance Of The ~21-17 Ka Dacitesmentioning

confidence: 99%

Fine-scale temporal recovery, reconstruction and evolution of a post-supereruption magmatic system

Barker

Wilson

Allan

et al. 2015

Contrib Mineral Petrol

214

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eruption of 25 rhyolitic units starting at ~12 ka. The dacites show strongly zoned minerals and wide variations in meltinclusion compositions, consistent with early magma mixing followed by periods of cooling and crystallisation at depths of >8 km, overlapping spatially with the inferred basal parts of the older Oruanui silicic mush system. The dacites reflect the first products of a new silicic system, as most of the Oruanui magmatic root zone was significantly modified in composition or effectively destroyed by influxes of hot mafic magmas following caldera collapse. The first rhyolites erupted between 12 and 10 ka formed through shallow (4-5 km depth) cooling and fractionation of melts from a source similar in composition to that generating the earlier dacites, with overlapping compositions for melt inclusions and crystal cores between the two magma types. For the successively younger rhyolite units, temporal changes in melt chemistry and mineral phase stability are observed, which reflect the development, stabilisation and maturation of a new, probably unitary, silicic mush system. This new mush system was closely linked to, and sometimes physically interacted with, underlying mafic melts of similar composition to those involved in the Oruanui supereruption. From the inferred depths of magma storage and geographical extent of vent sites, we consider that a large silicic mush system (>200 km 3 and possibly up to 1000 km 3 in volume) is now established at Taupo and is capable of feeding a new episode or cycle of volcanism at any stage in the future.

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Processes and time scales of dacite magma assembly and eruption at Tauhara volcano, Taupo Volcanic Zone, New Zealand

Cited by 23 publications

References 71 publications

Origin of Basalts by Hybridization in Andesite-dominated Arcs

Origin of Basalts by Hybridization in Andesite-dominated Arcs

Site U1531

Fine-scale temporal recovery, reconstruction and evolution of a post-supereruption magmatic system

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