Contrasting plagioclase textures and geochemistry in response to magma dynamics in an intra-caldera rhyolite system, Okataina volcano

Shane, Phil

doi:10.1016/j.jvolgeores.2015.03.013

Cited by 18 publications

(13 citation statements)

References 35 publications

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“…Several Kaharoa crystals exhibit boxy-cellular core textures 228 (Fig. 3A) that resemble chess boards, as noted by Shane (2015). Rotoma crystals rarely exhibit boxy-cellular 229 textures, but several crystals have distinct zones (≤80 µm in width) between the core and rim that are 230 dominated by inclusions (Fig.…”

Section: Methodsmentioning

confidence: 80%

“…Studies of rhyolitic deposits indicate that many OVC eruptions, both caldera-forming and intra-caldera, result 100 from influx of hotter mafic magma into cooler, multi-level and laterally discontinuous silicic reservoirs (e.g., 101 Leonard et al, 2002;Nairn et al, 2004Nairn et al, , 2005Nairn et al, , 2001Shane, 2015;Shane et al, 2008;Storm et al, 2014Storm et al, , 2012Storm et al, , 102 2011. 103…”

Section: Okataina Volcanic Centre and Sample Selection 89mentioning

confidence: 99%

“…The Kaharoa magmatic system has been modelled as a 118 stratified, sill-like (8 km x 1 km, >1 km in thickness) reservoir with three compositionally diverse and 119 individually homogeneous rhyolitic magmas: (1) T1, the first to erupt, (2) T2, the last to erupt and with higher 120 Zr and Sr relative to T1, and (3) T3, un-erupted rhyolite that mixed with basalt-derived residual melt (dacite) 121 to produce erupted rhyodacites (Nairn et al, 2004). Kaharoa was specifically selected based on previous 122 studies (Leonard et al, 2002;Nairn et al, 2004Nairn et al, , 2001Shane, 2015) that suggested multiple injections of 123 basalt into the Kaharoa sill occurred before eruption. Plagioclase used for analysis was extracted from T2, 124 because this unit shows greater evidence for interaction with basalt than T1, as well as representing the largest 125 volumetric component of the Kaharoa magmatic system (Nairn et al, 2004).…”

Section: Okataina Volcanic Centre and Sample Selection 89mentioning

confidence: 99%

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The ion microprobe as a tool for obtaining strontium isotopes in magmatic plagioclase: A case study at Okataina Volcanic Centre, New Zealand

et al. 2019

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We investigated the potential of multi-collector secondary ion mass spectrometry (MC-SIMS) as a 15 tool for obtaining Sr isotopic compositions in plagioclase, a ubiquitous mineral in igneous rocks that serves as 16 a recorder of crystallisation history. MC-SIMS allows for high spatial resolution analysis (~12 μm in this 17 study) of isotopes, and therefore improves the temporal scale at which fluctuations in crystallization 18 conditions can be recognized, ultimately improving our understanding of rates of magmatic processes. 19Plagioclase crystals from two young rhyolitic deposits from two major eruptive complexes, Tarawera and 20Haroharo, of the Okataina Volcanic Centre in New Zealand were analysed. Results were corrected for matrix 21 effects using linear modelling of MC-SIMS data versus An contents, as well as 87 Sr/ 86 Sr ratios acquired via 22 laser ablation inductively-coupled plasma mass spectrometry (LA-MC-ICP-MS). Corrected MC-SIMS Sr 23 isotopic ratios had an average 2σ uncertainty of ± 0.0008 per spot, and were homogeneous in Okataina 24 plagioclase at high spatial resolutions. Average LA-MC-ICP-MS 87 Sr/ 86 Sr ratios of plagioclase from both 25 intra-caldera volcanic complexes (Tarawera 87 Sr/ 86 Sr = 0.7056 and Haroharo 87 Sr/ 86 Sr = 0.7054) suggest 26 similar magma sources and similar assimilation and fractional crystallization processes for the two complexes. 27Overall homogeneity of plagioclase (excluding relict cores) indicates no significant changes in contributions 28 (i.e., crustal assimilation, mafic influx) to the system during the majority of plagioclase crystal growth. 29 Furthermore, lack of 87 Sr/ 86 Sr ratio fluctuations in plagioclase rims suggest interaction between the resident 30 silicic magma and the intruding mafic magma that triggered the eruptions was largely limited to volatile and 31 heat transfer. Using appropriate standards and analysis, this MC-SIMS method can be used to detect short-32 lived, open-system events in magma reservoirs where differences in 87 Sr/ 86 Sr isotopic ratios are significant.

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Section: Methodsmentioning

confidence: 80%

Section: Okataina Volcanic Centre and Sample Selection 89mentioning

confidence: 99%

Section: Okataina Volcanic Centre and Sample Selection 89mentioning

confidence: 99%

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The ion microprobe as a tool for obtaining strontium isotopes in magmatic plagioclase: A case study at Okataina Volcanic Centre, New Zealand

et al. 2019

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“…However, genesis models of other chaotic shapes of glomerocryst textures have been approached before, such as synneusis model (Vance 1969), accumulation model (Scoates 2000), heterogeneous nucleation model (Cheng et al, 2014), plagioclase resorption model (Hogan 1993) and single megacryst fragmentation model. Shane (2015) documented that the morphological texture (e.g. glomerocryst and synneusis) were formed by strong influences of crystallization kinetics in the magma chamber, such as convection, turbulence, degassing, magma mixing, and so on.…”

Section: Introductionmentioning

confidence: 99%

An Unique Glomerophyric Diorite Porphyry from the Southern Margin of North China Craton: Geochronology, Geochemical and Quantitative Textural Analysis Constraints

Zhu

Wang

2017

Acta Geologica Sinica (Eng)

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“…Thus, plagioclase textural and chemical variations have been widely used to reconstruct chamber dynamics, petrological processes and emplacement style from many volcanic provinces (e.g. Anderson, 1984;Nixon & Pearce, 1987;Singer et al, 1995;Davidson & Tepley, 1997;Tepley et al, 2000;Ginibre et al, 2002;Browne et al, 2006;Humphreys et al, 2006;Ruprecht & Wörner, 2007;Ginibre & Wörner, 2007;Gagnevin et al, 2007;Andrews et al, 2008;Viccaro et al, 2010Viccaro et al, , 2016Giacomini et al, 2014;Shane, 2015;Coote & Shane, 2016).…”

Section: Multi-collectormentioning

confidence: 99%

Petrological and volcanological insights into acid lavas from the Paraná-Etendeka Magmatic Province on the surroundings of Guarapuava city, Paraná, Southern Brazil: a contribution of detailed textural characterization combined with in situ Sr isotopes in plagioclase phenocrysts

Angelini¹

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contacts. Regardless of the petrographic association, the plagioclase is predominantly unzoned.Cathodoluminescence and scanning electron microscopy reveal the trachydacite groundmass to be composed of two petrographically distinct domains; one massive and continuous composed of a fine intergrowth of sanidine and quartz, and another one irregular and porous dominated only by sanidine.The dark bands observed on the respective outcrops are enriched in the former, whereas the light bands are relatively depleted in this and dominated by the latter type. All samples show concave-up crystal size distribution (CSD) curves, allowing sub-division in two groups: phenocrysts (> 3mm) and microphenocrysts (< 3mm). Such division bears relation with residence times and crystallization environment, estimated about 40 years in a deep-seated magmatic chamber (growth rate of 10 -9 mm.s together with the lack of pyroclastic textures/structures, ubiquitous presence of euhedral plagioclase crystals and isotopic homogeneity associated with the low water contents and high magmatic temperatures refutes a pyroclastic origin for such deposits. Otherwise, it is suggested a mainly effusive eruption style as vast acid lava flows fed by discrete conduits on the neighborhoods of Guarapuava.V AGRADECIMENTOSNinguém conquista nada e nem chega a lugar algum sozinho. A caminhada deste mestrado não foi diferente. Ele só foi possível graças a pessoas muito especiais que tenho a sorte de ter em minha vida e que mesmo diante dos momentos de desânimo, da falta de perspectiva, da grave crise financeira e política que o Brasil atravessa, nunca me deixaram pra baixo. Este trabalho é dedicado aos meus pais, Pedro e Nair. Por último, mas não menos importantes, este parágrafo é dedicado a todos meus amigos e amigas.Ano passado tive a honra de ser padrinho de dois casamentos, Juliana e Leandro e Lucas (Shun-Lee) e Asdra, sou muito grato pelo convite e mais uma vez desejo toda felicidade do mundo aos casais.Contem comigo pra tudo. Pra variar, amigos da Geologia, Santandreia F. R., vocês tornam tudo mais fácil e divertido, mesmo depois de quase 10 anos estamos firmes e fortes. Aliás, esse ano tem Cambury edição especial. Grandes amigos do Ofélia: Pará, Alê, Waldyr, Nico, Trick, Du, Caio, André, Secolin, Lucão, Pizzo, Flávio, Sylvio, valeu por tudo, é bom demais ter vocês como amigos. E, por fim, agradeço ao time de basquete da Geologia -USP. Que incrível descobrir um novo esporte depois de velho e aprender com alguns dos melhores jogadores da USP, muito obrigado e rumo ao tetra do BIFE.Tenho certeza que estou saindo deste mestrado uma pessoa melhor, um pesquisador mais crítico e um geólogo mais completo que quando entrei. Valeu a pena.VII

show abstract

Contrasting plagioclase textures and geochemistry in response to magma dynamics in an intra-caldera rhyolite system, Okataina volcano

Cited by 18 publications

References 35 publications

The ion microprobe as a tool for obtaining strontium isotopes in magmatic plagioclase: A case study at Okataina Volcanic Centre, New Zealand

The ion microprobe as a tool for obtaining strontium isotopes in magmatic plagioclase: A case study at Okataina Volcanic Centre, New Zealand

An Unique Glomerophyric Diorite Porphyry from the Southern Margin of North China Craton: Geochronology, Geochemical and Quantitative Textural Analysis Constraints

Petrological and volcanological insights into acid lavas from the Paraná-Etendeka Magmatic Province on the surroundings of Guarapuava city, Paraná, Southern Brazil: a contribution of detailed textural characterization combined with in situ Sr isotopes in plagioclase phenocrysts

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