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| Open AccessPost-eruptive mobility of lithium in volcanic rocks
Lithium, an increasingly economically important element, is also used to trace the cycling of materials through the Earth system. Here the authors show that post-eruptive processes such as degassing and groundmass crystallisation control the inventory of lithium in volcanic deposits.
- B. S. Ellis
- , D. Szymanowski
- & M. Guillong
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Article
| Open AccessArc-like magmas generated by mélange-peridotite interaction in the mantle wedge
Mélange rocks are predicted to form at the slab-mantle interface in most subduction zones, but their role in arc magmatism is still debated. Here, the authors show that melting of peridotite hybridized by mélange rocks produces melts that carry the major and trace element abundances of natural arc magmas.
- E. A. Codillo
- , V. Le Roux
- & H. R. Marschall
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| Open AccessCold deep subduction recorded by remnants of a Paleoproterozoic carbonated slab
The onset of modern-style plate tectonics remains under debate. Here, Xu et al. report a cold thermal-gradient recorded in an eclogite xenolith in Paleoproterozoic carbonatite from orogen, and propose that modern-style subduction has operated since at least the Paleoproterozoic.
- Cheng Xu
- , Jindřich Kynický
- & Yingwei Fei
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| Open AccessCrystal and melt inclusion timescales reveal the evolution of magma migration before eruption
Volatile contents in melt inclusions can be used to unravel magma migration and degassing. Here, the authors use olivine chronometry and melt inclusion data from the 2008 Llaima eruption and find that magma intrusion occurred 4 years before the eruption and reached a depth of 3–4 km, 6 months before the eruption.
- Dawn C. S. Ruth
- , Fidel Costa
- & Eliza S. Calder
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| Open AccessImmiscible hydrous Fe–Ca–P melt and the origin of iron oxide-apatite ore deposits
The origin of iron oxide-apatite deposits remains enigmatic and controversial. Here, the authors perform experiments on intermediate magmas and show that increasing aH2O and fO2 enlarges the two-liquid field thus allowing the Fe–Ca–P melt to separate easily from host silicic magma and produce iron oxide-apatite ores.
- Tong Hou
- , Bernard Charlier
- & Olivier Namur
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Article
| Open AccessTimescales of water accumulation in magmas and implications for short warning times of explosive eruptions
Volatiles such as water play a key role in magma ascent and ultimately triggering explosive eruptions. Here, the authors show that water-rich melts with water concentrations of 6–9 wt.% can ascend rapidly to the surface over the timescales of hours to days with very short warning times.
- M. Petrelli
- , K. El Omari
- & D. Perugini
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| Open AccessPeridotite weathering is the missing ingredient of Earth’s continental crust composition
The concentration of Ni and Cr of the continental crust cannot be explained by formation models involving differentiated magmatic rocks. Here, the authors show that hydrothermal alteration and chemical weathering of ultramafic rock compensates for the low Ni and Cr concentrations of island arc-type magmatic rocks.
- Andreas Beinlich
- , Håkon Austrheim
- & Andrew Putnis
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| Open AccessPlatinum-bearing chromite layers are caused by pressure reduction during magma ascent
Some basaltic melts become first superheated upon their ascent towards the Earth’s surface and then saturated in chromite alone after cooling in shallow chambers. Here the authors show that large volumes of these chromite-only-saturated melts are responsible for monomineralic layers of massive chromitites in layered intrusions.
- Rais Latypov
- , Gelu Costin
- & Tony Naldrett
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Article
| Open AccessVolcanic crystals as time capsules of eruption history
Crystals can record the timing of volcanic eruptive triggers at depth by examining their zoning histories. Here, the authors analyse clinopyroxene crystal zoning from eruptions at Mount Etna, Italy from 1974-2014 and show that the intrusion of magma can trigger an eruption within 2 weeks of arrival.
- Teresa Ubide
- & Balz S. Kamber
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Article
| Open AccessCrystal plasticity as an indicator of the viscous-brittle transition in magmas
The rheological behaviour of magma in shallow conditions may help determine a volcano’s eruptive style. Here, the authors perform deformation experiments on lava from Volcán de Colima to demonstrate that crystal plasticity may preclude failure at certain shallow magmatic conditions.
- J. E. Kendrick
- , Y. Lavallée
- & N. R. Varley
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| Open AccessMantle hydration and the role of water in the generation of large igneous provinces
The genesis of large igneous provinces (LIPs) remains controversial. Here, the authors examine the water contents of picrites from the Emeishan LIP and find that despite high water contents, the elevated temperature and trace elements suggest a mantle plume from a hydrous deep reservoir rather than subduction zone related.
- Jia Liu
- , Qun-Ke Xia
- & Hao-Ran Yu
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| Open AccessCaldera resurgence driven by magma viscosity contrasts
Following a large caldera creating volcanic eruption, caldera resurgence may occur as magma accumulation takes place, but this rarely leads to another a major eruption. Here, the authors using thermal and experimental models show that caldera resurgence is driven by magma viscosity contrasts.
- Federico Galetto
- , Valerio Acocella
- & Luca Caricchi
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| Open AccessPlume-subduction interaction forms large auriferous provinces
The lithospheric controls on giant gold deposits remain unclear. Here, the authors show evidence for native gold in the mantle from the Deseado Massif in Patagonia demonstrating that refertilisation of the lithospheric mantle is key in forming metallogenic provinces.
- Santiago Tassara
- , José M. González-Jiménez
- & Alexandre Corgne
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| Open AccessArchaean and Proterozoic diamond growth from contrasting styles of large-scale magmatism
Dating of inclusions within diamonds is used to reconstruct Earth’s geodynamic history. Here, the authors report isotope data on individual garnet inclusions within diamonds from Venetia, South Africa, showing that two suites of diamonds define two isochrons, showing the importance of dating individual inclusions.
- Janne M. Koornneef
- , Michael U. Gress
- & Gareth R. Davies
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| Open AccessSilicate dissolution boosts the CO2 concentrations in subduction fluids
Current estimates of dissolved CO2 in subduction-zone fluids based on thermodynamic models rely on a very sparse experimental data base. Here, the authors show that experimental graphite-saturated COH fluids interacting with silicates at 1–3 GPa and 800 °C display unpredictably high CO2 contents.
- S. Tumiati
- , C. Tiraboschi
- & S. Poli
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| Open AccessLithium enrichment in intracontinental rhyolite magmas leads to Li deposits in caldera basins
Lithium is increasingly being utilized for modern technology in the form of lithium-ion batteries. Here, using in situ measurements of quartz-hosted melt inclusions, the authors demonstrate that preserved lake sediments within rhyolitic calderas have the potential to host large lithium-rich clay deposits.
- Thomas R. Benson
- , Matthew A. Coble
- & Gail A. Mahood
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Article
| Open AccessReduced and unstratified crust in CV chondrite parent body
Meteorites may unlock the history of the early solar system. Here, the authors find, through Ca-Fe-rich secondary phases, that the distinction between reduced and oxidized CV chondrites is invalid; therefore, CV3 chondrites are asteroid fragments that percolated heterogeneously via porous flow of hydrothermal fluid.
- Clément Ganino
- & Guy Libourel
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Article
| Open AccessImmiscible hydrocarbon fluids in the deep carbon cycle
Carbon migration in the deep Earth is still not fully understood. Here, the authors show that immiscible isobutane formsin situfrom transformation of aqueous sodium acetate at 300 °C and 2.4–3.5 GPa, indicating that hydrocarbon fluids may play a major role in carbon transfer in the deep carbon cycle.
- Fang Huang
- , Isabelle Daniel
- & Dimitri A. Sverjensky
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| Open AccessMelting temperatures of MgO under high pressure by micro-texture analysis
Melting behaviour of MgO under pressure remains unclear despite the importance of constraining the rheology and composition of the Earth’s mantle. Here, the authors show that melting temperatures in earlier static experiments were underestimated based on micro-texture analysis of the quenched samples.
- T. Kimura
- , H. Ohfuji
- & T. Irifune
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| Open AccessPost-supereruption recovery at Toba Caldera
Toba Caldera in Indonesia had one of the largest volcanic eruptions over the last 100 kyr and has since undergone periods of resurgence. Here, the authors present zircon and sediment age data showing resurgence started after the climactic eruption and lasted until 2.7 ka, advancing west and south.
- Adonara E. Mucek
- , Martin Danišík
- & Matthew A. Coble
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Article
| Open AccessShock-transformation of whitlockite to merrillite and the implications for meteoritic phosphate
Quantifying the amount of water in meteorites remains challenging, with minerals the key to understanding water contents. Here, Adcocket al. perform shock experiments on H+-bearing whitlockite demonstrating that it may transform into anhydrous merrillite, which is commonly found in Martian meteorites.
- C. T. Adcock
- , O. Tschauner
- & C. Lin
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| Open AccessMassive production of abiotic methane during subduction evidenced in metamorphosed ophicarbonates from the Italian Alps
Alteration of ultramafic rocks plays a role in hydrocarbon production, but little is known about this process at depth. Here, the authors provide evidence that alteration of carbonated ultramafic rocks at high-pressures are an important source of abiotic methanogenesis with implications for deep C mobility.
- Alberto Vitale Brovarone
- , Isabelle Martinez
- & Imène Esteve
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| Open AccessIron isotopic fractionation between silicate mantle and metallic core at high pressure
Terrestrial basalts have a unique iron isotopic signature taken as fingerprints of core formation. Here, high pressure studies show that force constants of iron bonds increase with pressure similarly for silicate and metals suggesting interplanetary isotopic variability is not due to core formation.
- Jin Liu
- , Nicolas Dauphas
- & Jung-Fu Lin
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| Open AccessBoninite-like intraplate magmas from Manihiki Plateau require ultra-depleted and enriched source components
Large igneous provinces may form very quickly, but compositions often differ. Here, the authors find that boninite-like rocks at Manihiki are a result of re-melting of an ultra-depleted source therefore putting into question that all boninitic rocks on Earth must be related to subduction processes.
- Roman Golowin
- , Maxim Portnyagin
- & Simon Turner
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| Open AccessPetit-spot as definitive evidence for partial melting in the asthenosphere caused by CO2
The genesis of primitive CO2-rich alkali magma at petit-spot volcanoes is still poorly understood. Here, the authors perform high pressure and temperature experiments to show that the CO2-rich melt is derived from the asthenosphere.
- Shiki Machida
- , Tetsu Kogiso
- & Naoto Hirano
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| Open AccessMineral inclusions in diamonds may be synchronous but not syngenetic
Trapped mineral inclusions in diamonds give information on diamond crystallization and ages, under the assumption that they are syngenetic (formed simultaneously). Here, the authors show evidence that many mineral inclusions are protogenetic (formed at different times) thus undermining previous diamond ages.
- Fabrizio Nestola
- , Haemyeong Jung
- & Lawrence A. Taylor
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| Open AccessHeterogeneity in mantle carbon content from CO2-undersaturated basalts
Melting dynamics are affected by the amount of carbon in the Earth’s mantle. Le Voyeret al. report undegassed carbon concentrations from olivine-hosted melt inclusions from the Mid-Atlantic Ridge finding that carbon content varies by two orders of magnitude thus introducing heterogeneity into the upper mantle.
- M. Le Voyer
- , K.A. Kelley
- & E.H. Hauri
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| Open AccessRole of syn-eruptive plagioclase disequilibrium crystallization in basaltic magma ascent dynamics
The quantification of timing for crystallization and exsolution processes are fundamental to our understanding of basaltic magma ascent dynamics. Here, the authors constrain timings to show that plagioclase reaches equilibrium in 1-2 hours, whereas ascent times were <1 hour.
- G. La Spina
- , M. Burton
- & F. Arzilli
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| Open AccessU–Pb geochronology documents out-of-sequence emplacement of ultramafic layers in the Bushveld Igneous Complex of South Africa
Large igneous intrusions layering is thought to represent an upward-aggrading crystal pile. However, Mungallet al.show that the Rustenburg Layered Suite of the Bushveld Complex, South Africa was created by the injection of a series of thin sheet-like intrusions that cooled and solidified as separate bodies.
- James E. Mungall
- , Sandra L. Kamo
- & Stewart McQuade
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| Open AccessRecord of massive upwellings from the Pacific large low shear velocity province
Large igneous provinces may record pulses mantle plume upwellings and their relationship with deep-rooted mantle sources. Madrigal et al. present a new petrological model of the Pacific Ocean Large Igneous Province finding that mantle plume pulses were separated by 10–20 Ma.
- Pilar Madrigal
- , Esteban Gazel
- & Brian Jicha
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| Open AccessPre-eruptive magmatic processes re-timed using a non-isothermal approach to magma chamber dynamics
Zoned crystals may reflect magma chamber dynamics, where changes in temperature, pressure and timescale before volcanic eruption may be measured. Petrone et al. develop a new Non-Isothermal Diffusion Incremental Step model to reconstruct crystal lifetime histories to constrain pre-eruptive magmatic processes.
- Chiara Maria Petrone
- , Giuseppe Bugatti
- & Simone Tommasini
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| Open AccessReaction-induced rheological weakening enables oceanic plate subduction
Plate subduction initiation requires weak boundaries between tectonic plates, but how weaknesses develop is unclear. Here, using high-pressure friction experiments on peridotite gouge material, the authors show that hydration reactions contribute to the weak mantle shear zones leading to subduction initiation.
- Ken-ichi Hirauchi
- , Kumi Fukushima
- & Atsushi Okamoto
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| Open AccessObservational evidence confirms modelling of the long-term integrity of CO2-reservoir caprocks
Anthropogenic CO2 storage, where CO2 is injected into saline geological resevoirs, relies on an impermeable caprock to seal in the CO2, but caprock reaction rates to CO2 acid brines are unclear. Here, Kampman et al. show that mineral reaction front alteration in caprocks takes place over 100,000 years.
- N. Kampman
- , A. Busch
- & M. J. Bickle
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| Open AccessPliocene-Quaternary crustal melting in central and northern Tibet and insights into crustal flow
The role of the low velocity-high conductivity zones (LV–HCZs) in developing the Tibetan Plateau has remained controversial. Here, Wang et al.present new geochemical and petrological data that show the LV–HCZs are sources of partial melt thus giving insight into the development of the Tibetan Plateau.
- Qiang Wang
- , Chris J. Hawkesworth
- & Yan-Hui Dong
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Article
| Open AccessHigh-temperature water–rock interactions and hydrothermal environments in the chondrite-like core of Enceladus
Observations indicate that the southern hemisphere of Enceladus is geologically active, with spray containing Si nanoparticles being ejected from an underground ocean. Here, the authors report that experiments to constrain reaction conditions suggest the core is similar to that of carbonaceous chondrites.
- Yasuhito Sekine
- , Takazo Shibuya
- & Sin-iti Sirono
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Did diamond-bearing orangeites originate from MARID-veined peridotites in the lithospheric mantle?
Due to entrainment of mantle and crustal fragments, orangeites provide information about the deep Earth; however, the nature of the source of orangeites remains uncertain. Here, the authors suggest that mica-amphibole-rutile-ilmenite-diopside (MARID) enriched mantle produces the orangeite magmas.
- Andrea Giuliani
- , David Phillips
- & Richard A. Armstrong
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| Open AccessPartial melting of deeply subducted eclogite from the Sulu orogen in China
Natural examples of eclogite-derived migmatite were previously unknown. Here, the authors show evidence of high-pressure melting of eclogite in the Sulu orogen of China, and suggest the melts represent an exhumed example of flow channels in the lower crust, possibly a source of syn-exhumation magmas.
- Lu Wang
- , Timothy M. Kusky
- & Jianmin Fu
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On the conditions of magma mixing and its bearing on andesite production in the crust
Andesites are a large part of the continental crust, but their origins remain enigmatic. Here, the authors update older mixing models via high-temperature experiments and thermal calculations, showing that homogeneous mixtures are only possible with high mafic fractions and during high magma flux.
- Mickael Laumonier
- , Bruno Scaillet
- & Laurent Arbaret
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Geochemistry of silicate-rich rocks can curtail spreading of carbon dioxide in subsurface aquifers
Carbon sequestration will be vital in mitigating future climate change, and understanding how CO2 behaves in aquifers is important for developing technologies. Here, the authors suggest that silicate-rich rocks inhibit the transport of CO2, which may have consequences for future engineered storage facilities.
- S. S. S. Cardoso
- & J. T. H. Andres
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Article |
Ediacaran 2,500-km-long synchronous deep continental subduction in the West Gondwana Orogen
The West Gondwana Orogen is a major continental collision zone exposing numerous eclogites along its strike. Here, the authors present zircon data from eclogites in Mali, Togo and NE Brazil, which indicate that continental subduction occurred simultaneously over at least 2,500 km during the Ediacaran.
- Carlos E. Ganade de Araujo
- , Daniela Rubatto
- & Miguel A. S. Basei
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Article
| Open AccessWeibull-distributed dyke thickness reflects probabilistic character of host-rock strength
Understanding dyke thickness distributions is essential to quantify magma transport rates and improve eruption forecasting. Krumbholz et al.show that dyke thicknesses are Weibull-distributed and identify host-rock strength as the primary parameter that controls dyke emplacement.
- Michael Krumbholz
- , Christoph F. Hieronymus
- & Nadine Friese
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The discovery of kimberlites in Antarctica extends the vast Gondwanan Cretaceous province
Kimberlite, an igneous rock in which the majority of the world’s diamonds are found, has been reported on all major continents barring Antarctica. Yaxley et al. present mineralogical and chemical data that confirms the first bona fidediscovery of kimberlite in the Antarctic.
- Gregory M. Yaxley
- , Vadim S. Kamenetsky
- & Marc Norman
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| Open AccessThe importance of stress percolation patterns in rocks and other polycrystalline materials
All rocks contain patterns, but how they form is not clear. Here, finite element models are used to show that grain-to-grain variations in elastic moduli cause stress to percolate in polycrystalline materials, causing shear localization and providing a template for foliation development in rocks.
- P.C. Burnley
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Pyroclastic passage zones in glaciovolcanic sequences
Subglacial volcanoes host passage zones that can be used to define high stands of englacial lakes and paleo-ice thickness. This study identifies a pyroclastic passage zone in a subglacial volcano, which may help calculate transient paleolake levels and improve estimates of paleo-ice thickness.
- James K. Russell
- , Benjamin R. Edwards
- & Lucy A. Porritt
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The origin of pelletal lapilli in explosive kimberlite eruptions
Kimberlites are volatile-rich magmas that form diverging pipes containing pelletal lapilli - well rounded clasts that consist of an inner seed particle. Gernonet al. suggest that pelletal lapilli are formed when fluid volatile-rich melts intrude into earlier volcaniclastic infill close to the diatreme root zone.
- T.M. Gernon
- , R.J. Brown
- & T.K. Hincks