Chasing the mantle: Deciphering cryptic mantle signals through Earth's thickest continental magmatic arc

Burns, Dale H.; Silva, De; Tepley, F. J.; Schmitt, Axel K.

doi:10.1016/j.epsl.2019.115985

Cited by 10 publications

(8 citation statements)

References 47 publications

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“…felsic melts derived from the APMB as these mafic melts by-passed the molten APMB body. At these crustal levels, olivine and subsequent clinopyroxene crystallisation occurred, which is consistent with recent thermobarometric estimations performed in Quaternary lavas from the southwestern border of the Altiplano-Puna Volcanic Complex 28 .…”

Section: Scientific Reports |supporting

confidence: 90%

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Constraining the sub-arc, parental magma composition for the giant Altiplano-Puna Volcanic Complex, northern Chile

González-Maurel

Deegan

Roux

et al. 2020

Sci Rep

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The Andean continental arc is built upon the thickest crust on Earth, whose eruption products reflect varying degrees of crustal assimilation. In order to robustly model magma evolution and assimilation at subduction zones such as the Andes, the compositions of parental magmas feeding crustal magma reservoirs need to be defined. Here we present new olivine and clinopyroxene oxygen isotope data from rare mafic volcanic rocks erupted at the margins of the giant Altiplano-Puna Magma Body (APMB) of the Altiplano-Puna Volcanic Complex, Central Andes. Existing olivine and pyroxene δ18O values for the Central Andes are highly variable and potentially not representative of sub-arc parental compositions. However, new olivine (n = 6) and clinopyroxene (n = 12) δ18O values of six Central Andean volcanoes presented here display a narrow range, with averages at 6.0‰ ± 0.2 (2σ S.D.) and 6.7‰ ± 0.3 (2σ S.D.), consistent with a common history for the investigated minerals. These data allow us to estimate the δ18O values of sub-arc, parental melts to ca. 7.0‰ ± 0.2 (2σ S.D.). Parental melts feeding the APMB and associated volcanic centres are postulated to form in the felsic continental crust following assimilation of up to 28% high-δ18O basement rocks by mantle-derived magmas.

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Section: Scientific Reports |supporting

confidence: 90%

“…It is thus possible that pyroxene crystallised at a higher crustal level than olivine and might record late-stage crustal assimilation (cf. [26][27][28] ). We also note that arc lava pyroxenes frequently contain inclusions of plagioclase (which would have higher δ 18 O values) and/or oxides (lower δ 18 O values) (e.g.…”

Section: Discussionmentioning

confidence: 99%

Constraining the sub-arc, parental magma composition for the giant Altiplano-Puna Volcanic Complex, northern Chile

González-Maurel

Deegan

Roux

et al. 2020

Sci Rep

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“…It is more mafic than any of the available mafic enclaves in the Cerro Blanco system in Bardelli et al (2020), which we would argue from regional perspectives are likely to have been precontaminated before being fed into the Cerro Blanco rhyolitic magma complex. Whereas it is likely that JC131 itself is contaminated (for constraints on the mantle-derived compositions, see discussions in Francis et al, 1989;Davidson et al, 1991;Kay et al, 1994;Trumbull et al, 1999;Drew et al, 2009;Risse et al, 2013;Maro et al, 2017;Burns et al, 2019), for our purposes of testing upper-crustal evolution, we argue that it is a reasonable local parental mafic end member.…”

Section: Origin Of the Rhyolites As A Distinct Suite In The Southern ...mentioning

confidence: 84%

Magmatic evolution and architecture of an arc-related, rhyolitic caldera complex: The late Pleistocene to Holocene Cerro Blanco volcanic complex, southern Puna, Argentina

et al. 2022

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Through the lens of bulk-rock and matrix glass geochemistry, we investigated the magmatic evolution and pre-eruptive architecture of the siliceous magma complex beneath the Cerro Blanco volcanic complex, a Crater Lake–type caldera complex in the southern Puna Plateau of the Central Andes of Argentina. The Cerro Blanco volcanic complex has been the site of two caldera-forming eruptions with volcanic explosivity index (VEI) 6+ that emplaced the ca. 54 ka Campo Piedra Pomez ignimbrite and the ca. 4.2 ka Cerro Blanco ignimbrite. As such, it is the most productive recent explosive volcano in the Central Andes. The most recent eruptions (younger than 4.2 ka) are dominantly postcaldera effusions of crystal-rich domes and associated small explosive pulses. Previous work has demonstrated that andesitic recharge of and mixing with rhyolitic magma occurred at the base of the magma complex, at ~10 km depth. New isotopic data (Sr, Nd, Pb, and O) confirm that the Cerro Blanco volcanic complex rhyolite suite is part of a regional southern Puna, arc-related ignimbrite group. The suite defines a tight group of consanguineous siliceous magmas that serves as a model for the evolution of arc-related, caldera-forming silicic magma systems in the region and elsewhere. These data indicate that the rhyolites originated through limited assimilation of and mixing with upper-crustal lithologies by regional basaltic andesite parent materials, followed by extensive fractional crystallization. Least squares models of major elements in tandem with Rayleigh fractionation models for trace elements reveal that the internal variations among the rhyolites through time can be derived by extensive fractionation of a quartz–two feldspar (granitic minimum) assemblage with limited assimilation. The rare earth element character of local volumes of melt in some samples of the Campo Piedra Pomez ignimbrite basal fallout requires significant fractionation of amphibole. The distinctive major- and trace-element characteristics of bulk rock and matrix of the Campo Piedra Pomez and Cerro Blanco tephras provide useful geochemical fingerprints to facilitate regional tephrochronology. Available data indicate that rhyolites from other neighborhood centers, such as Cueros de Purulla, share bulk chemical characteristics with the Campo Piedra Pomez ignimbrite rhyolites, but they appear to be isotopically distinct. Pre-eruptive storage and final equilibration of the rhyolitic melts were estimated from matrix glass compositions projected onto the haplogranitic system (quartz-albite-orthoclase-H2O) and using rhyolite-MELTS models. These revealed equilibration pressures between 360 and 60 MPa (~10–2 km depth) with lowest pressures in the Holocene eruptions. Model temperatures for the suite ranged from 695 to 790 °C. Integrated together, our results reveal that the Cerro Blanco volcanic complex is a steady-state (low-magmatic-flux), arc-related complex, standing in contrast to the flare-up (high-magmatic-flux) supervolcanoes that dominate the Neogene volcanic stratigraphy. The silicic magmas of the Cerro Blanco volcanic complex were derived more directly from mafic and intermediate precursors through extensive fractional crystallization, albeit with some mixing and assimilation of local basement. Geochemical models and pressure-temperature estimates indicate that significant volumes of remnant cumulates of felsic and intermediate composition should dominate the polybaric magma complex beneath the Cerro Blanco volcanic complex, which gradually shallowed through time. Evolution to the most silicic compositions and final equilibration of some of the postcaldera domes occurred during ascent and decompression at depths less than 2 km. Our work connotes an incrementally accumulated (over at least 54 k.y.), upper-crustal pluton beneath the Cerro Blanco volcanic complex between 2 and 10 km depth. The composition of this pluton is predicted to be dominantly granitic, with deeper parts being granodioritic to tonalitic. The progressive solidification and eventual contraction of the magma complex may account for the decades of deflation that has characterized Cerro Blanco. The presently active geothermal anomaly and hydrothermal springs indicate the Cerro Blanco volcanic complex remains potentially active.

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“…We also present 17 new major and trace element analyses, and three new 87 Sr/ 86 Sr isotope measurements from the Purico-Chascon volcanic complex in N. Chile. New samples are restricted to the 1 Ma Purico ignimbrite, Cerro Purico lava dome, and Dome D (Hawkesworth et al, 1982;Schmitt et al, 2001;Burns et al, 2015;Burns et al, 2020). These new analyses represent andesites associated with the peak of the regional ignimbrite flare-up and fill a critical gap in understanding of andesites in the CVZ.…”

Section: Methods and Data Filtrationmentioning

confidence: 96%

“…Between 10 and 1 Ma, estimated magmatic fluxes appear to have increased by more than an order-of-magnitude relative to steady-state CVZ magmatism (de Silva et al, 2006;de Silva and Gosnold, 2007;Burns et al, 2015), resulting in the eruption of >15,000 km 3 of mainly crystal-rich dacite magma (de Silva and Gosnold, 2007). After the peak of the flare-up, ~4 Ma, eruptive activity in the region appears to start waning and the re-emergence of composite volcanoes, small-volume lava domes, and volumetrically dominant andesite (de Silva et al, 1994;Watts et al, 1999;Grunder et al, 2008;Tierney et al, 2016;Godoy et al, 2019) has signaled a return to steadystate conditions (Burns et al, 2015;Burns et al, 2020). In addition to major tectono-magmatic events causing arc-scale changes in crustal architecture and processes, the CVZ arc is built on multiple temporally and compositionally distinct crustal domains that play a significant role in the generation and evolution of the subduction-derived magmas (e.g., Barreiro and Clark, 1984;Aitcheson et al, 1995;Wörner et al, 1994;Mamani et al, 2008).…”

Section: Geological Backgroundmentioning

confidence: 99%

Andesites and evolution of the continental crust: Perspectives from the Central Volcanic Zone of the Andes

Burns

Silva

2023

Front. Earth Sci.

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Named for the Andes, andesites (53%–63% SiO2) are the archetypal magma erupted at magmatic arcs. They have been established as the average composition of continental crust and as such are integral to the growth and evolution of the continental crust. However, andesites are quite variable in trace element and isotopic composition reflecting disparate paths of origin. Herein we return to the original site of their identification, the Central Andes, and use a comprehensive dataset of published and unpublished trace elements and isotopes to show that during the past 6 Myr two distinct types of andesite have erupted in the Central Volcanic Zone (CVZ), which correspond with different geodynamic conditions. Consistent with previous work, we confirm that major composite cones and minor centers of the steady state (low magmatic flux) Quaternary CVZ arc have trace element and isotopic characteristics consistent with magma generation/fractionation in the lower crust. Within the Quaternary arc centers, there are also significant latitudinal variations that correspond with the age, composition, and P-T conditions of the lower crust. However, in contrast to this prevailing model, in the 21–24°S segment 6–1 Ma andesites from ignimbrites and lava domes associated with the peak of the regional Neogene ignimbrite flare-up have compositions that indicate these andesites are hybrids between mantle-derived basalts and upper crustal lithologies. Since ∼1 Ma, andesites in young silicic lava domes associated with the regional flare-up are compositionally indistinguishable from proximal Quaternary arc centers, indicating a return to steady-state magmatism and lower crustal production of andesites. We propose that the transition from upper crustal to lower crustal andesite production results from a decrease in mantle heat input and subsequent relaxation of the regional geotherm during the waning of the flare-up event. The two modes of andesite production have significant implications for the production and evolution of the CVZ arc crust. During the flare-up, prodigious amounts of basalt were emplaced into the mid-crust, resulting in the production of large volumes of hybrid intermediate magmas in the mid and upper crust. In contrast, the lower crustal differentiation recorded in the Quaternary steady state arc andesites would result in the formation of a dense crystalline residue in the lower crust and an overall densification of the lower crust. Over time, gravity instabilities associated with this densification may ultimately aid in the delamination of the dense lower crustal root, triggering flare-ups. These differences in andesite production may help explain the cyclicity (flare-up cycles) observed in mature continental arcs and emphasizes that andesite is not a monotonous composition and can vary with depth-dependent intra-crustal differentiation related to magmatic flux.

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Chasing the mantle: Deciphering cryptic mantle signals through Earth's thickest continental magmatic arc

Cited by 10 publications

References 47 publications

Constraining the sub-arc, parental magma composition for the giant Altiplano-Puna Volcanic Complex, northern Chile

Constraining the sub-arc, parental magma composition for the giant Altiplano-Puna Volcanic Complex, northern Chile

Magmatic evolution and architecture of an arc-related, rhyolitic caldera complex: The late Pleistocene to Holocene Cerro Blanco volcanic complex, southern Puna, Argentina

Andesites and evolution of the continental crust: Perspectives from the Central Volcanic Zone of the Andes

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