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| Open AccessOlivine-rich achondrites from Vesta and the missing mantle problem
Ultramafic olivine-rich achondrites provide insight into the missing mantle problem in the asteroid belt. The petrology and geochemistry of these samples suggests they are related to Vesta or the Vestoids.
- Zoltan Vaci
- , James M. D. Day
- & Andreas Pack
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Article
| Open AccessEpisodic construction of the early Andean Cordillera unravelled by zircon petrochronology
Episodic magmatism of the early Andes is the result of a complex interplay between mantle, crust, slab and sediment contributions that can be traced using zircon chemistry. An external (tectonic) model is argued for the episodic plutonism in this extensional continental arc.
- José Joaquín Jara
- , Fernando Barra
- & Diego Morata
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Perspective
| Open AccessThe search for lunar mantle rocks exposed on the surface of the Moon
Vast, ancient impact basins scattered mantle materials across the lunar surface. We review lunar evolution models to identify candidate mantle lithologies, then assess orbital observations to evalutae the current distribution of these materials and implications for fundamental planetary processes.
- Daniel P. Moriarty III
- , Nick Dygert
- & Noah E. Petro
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Article
| Open AccessMassive carbon storage in convergent margins initiated by subduction of limestone
Experiments and buoyancy calculations reveal that subduction of limestone results in massive carbon storage in arc lithosphere, forming an important carbon reservoir in convergent margins. Remobilization of this carbon reservoir during arc magma ascent may dominate carbon emissions at volcanic arcs.
- Chunfei Chen
- , Michael W. Förster
- & Yongsheng Liu
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Article
| Open AccessUncovering the eruptive patterns of the 2019 double paroxysm eruption crisis of Stromboli volcano
Integrated field and laboratory investigations, and numerical simulations of the 2019 paroxysmal explosions at Stromboli volcano revealed that they were anticipated by a week-to-month-long destabilization in the normal volcanic activity, a pattern common to all paroxysms.
- Daniele Andronico
- , Elisabetta Del Bello
- & Federico Valentini
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| Open AccessOut-of-sequence skeletal growth causing oscillatory zoning in arc olivines
Arc olivines are commonly explained through a paradigm of core-to-rim sequential growth and oscillatory zoning is interpreted to represent magma mixing. Here the authors show Fo–Ni–P oscillatory zoned olivines can grow as out-of-sequence crystal frames and complex zoning can occur in closed systems.
- Pablo Salas
- , Philipp Ruprecht
- & Osvaldo Rabbia
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Article
| Open AccessSunda arc mantle source δ18O value revealed by intracrystal isotope analysis
Subduction zone volcanoes are underlain by extensive magma plumbing systems, which can obscure original mantle source signals. Here, the authors show that intra-crystal oxygen isotope analysis of clinopyroxenes from the Sunda arc (Indonesia) reveal the δ18 O value of the sub-arc mantle.
- Frances M. Deegan
- , Martin J. Whitehouse
- & Osvaldo González-Maurel
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Article
| Open AccessHelium in diamonds unravels over a billion years of craton metasomatism
Diamonds encapsulate the deep Earth fluids that form them, providing windows to deep mantle processes. This study constrains their ages, based on uranium-thorium-to-helium radioactive decay in the fluids and helium diffusivity in diamond, and relates diamond formation to geological events in Southern Africa.
- Yaakov Weiss
- , Yael Kiro
- & Steven L. Goldstein
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Article
| Open AccessCalcium isotope evidence for early Archaean carbonates and subduction of oceanic crust
Phase equilibrium modelling combined with Ca isotope measurements in ancient granitoids demonstrates that subduction of oceanic crust occurred repeatedly throughout the Archaean and that carbonate sediments were present in early Eoarchaean oceans (>3.8 billion years).
- Michael A. Antonelli
- , Jillian Kendrick
- & Frédéric Moynier
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Article
| Open AccessBasalt derived from highly refractory mantle sources during early Izu-Bonin-Mariana arc development
Magmatism associated with early growth of subduction zones is unlike that of mature island arc systems. Here, the authors find basalts with distinct mineralogical and geochemical characteristics were erupted during this early stage, and derived from extremely refractory, hot mantle sources.
- He Li
- , Richard J. Arculus
- & Weidong Sun
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Article
| Open AccessChemical feedbacks during magma degassing control chlorine partitioning and metal extraction in volcanic arcs
Chlorine behaviour during complex, polybaric arc magma degassing is poorly understood. Here, the authors show that chemical feedbacks during coeval magma differentiation and degassing account for the Cl record at both volcanoes and ore deposits, and quantify the role of Cl in efficient copper extraction during degassing.
- B. Tattitch
- , C. Chelle-Michou
- & R. R. Loucks
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Article
| Open AccessMelting of subducted sediments reconciles geophysical images of subduction zones
Here, the authors identify that magnetotelluric conductive anomalies commonly observed on the trenchward-side of volcanic arcs in subduction zones can be explained by subducted sediments. High-pressure experiments show that these sediment melts will react with the overlying mantle wedge to produce electrically conductive phlogopite pyroxenites.
- M. W. Förster
- & K. Selway
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Article
| Open AccessExtreme isotopic heterogeneity in Samoan clinopyroxenes constrains sediment recycling
Subduction of oceanic crust and sediments contributes to heterogeneities in the mantle, which are sampled by mantle plumes. Here, the authors find that extreme isotopic heterogeneity in Samoan clinopyroxenes can help constrain the composition of mantle sources containing sediment recycled into the Earth’s mantle.
- Jenna V. Adams
- , Matthew G. Jackson
- & John M. Cottle
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Article
| Open AccessDepth-dependent peridotite-melt interaction and the origin of variable silica in the cratonic mantle
The compositional variability amongst Archaean cratonic peridotites has long been recognized, however its origin remains debated. The authors here find that the collapse of the dual Archaean mantle melting environment ceased production of silica-enriched mantle lithosphere.
- Emma L. Tomlinson
- & Balz S. Kamber
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Article
| Open AccessThe Rustenburg Layered Suite formed as a stack of mush with transient magma chambers
The Rustenburg Layered Suite of the Bushveld Complex, South Africa, has long been regarded as a textbook result of fractional crystallization from a melt-dominated magma chamber. Here, the authors find that the Rustenburg Layered Suite can be derived from crustal assimilation by komatiitic magma to form magmatic mushes without requiring the existence of a magma chamber by using thermodynamic models.
- Zhuosen Yao
- , James E. Mungall
- & M. Christopher Jenkins
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Article
| Open AccessPervasive subduction zone devolatilization recycles CO2 into the forearc
The fate of subducted CO2 remains debated, with estimates mainly from numerical predictions varying from wholesale decarbonation of the shallow subducting slab to massive deep subduction of CO2. Here, the authors present field-based data and show that ~40% to ~65% of the CO2 in subducting crust is released via metamorphic decarbonation reactions at forearc depths.
- E. M. Stewart
- & Jay J. Ague
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Article
| Open AccessDetermining the current size and state of subvolcanic magma reservoirs
This study makes use of the total spread of zircon ages and trace elements to study the thermal evolution of magmatic systems. Applied to Nevado de Toluca, the authors determine the size of its subvolcanic magma reservoir and assess its potential of re-activation.
- Gregor Weber
- , Luca Caricchi
- & Axel K. Schmitt
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Article
| Open AccessLithium systematics in global arc magmas and the importance of crustal thickening for lithium enrichment
The exact origin of lithium enrichment in arc magmatic systems is unclear. Here the authors conduct a global systematics of lithium, explaining why volcanic arcs built on thickened crust are most lithium-enriched, which sheds light on the future exploration of lithium resources.
- Chen Chen
- , Cin-Ty A. Lee
- & Weidong Sun
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Article
| Open AccessEpisodes of fast crystal growth in pegmatites
Pegmatite crystals are thought to grow rapidly, yet their growth rates and conditions are not well constrained. Here, the authors find that the trace element distributions of pegmatitic quartz crystals indicate rapid growth in highly dynamic environments, suggesting that large meter-scale crystals can be formed within days.
- Patrick R. Phelps
- , Cin-Ty A. Lee
- & Douglas M. Morton
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Article
| Open AccessStructural dynamics of basaltic melt at mantle conditions with implications for magma oceans and superplumes
Transport properties of melts in the deep Earth have dictated the evolution of the early Earth’s magma oceans and also govern many modern dynamic processes, such as plate tectonics. Here, the authors find there is a reversal in the trends of transport properties of basaltic melts at pressures near 50 GPa, with implications for the timescales of early Earth’s magma oceans.
- Arnab Majumdar
- , Min Wu
- & John S. Tse
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Article
| Open AccessFluxing of mantle carbon as a physical agent for metallogenic fertilization of the crust
Magmatic systems play a crucial role in enriching the crust with volatiles and elements that reside primarily within the Earth’s mantle. Here, the authors show that carbon, as a buoyant supercritical CO2 fluid, could be a covert agent that may promote the physical transport of sulfides across the mantle-crust transition.
- Daryl E. Blanks
- , David A. Holwell
- & Elena Ferrari
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Article
| Open AccessRecycled arc mantle recovered from the Mid-Atlantic Ridge
Plate tectonics necessitates mantle recycling throughout Earth’s history, yet direct geochemical evidence for mantle reprocessing remains elusive. Here, the authors present evidence of recycled supra-subduction zone mantle wedge peridotite dredged from the Mid-Atlantic Ridge near 16°30′N.
- B. M. Urann
- , H. J. B. Dick
- & J. F. Casey
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| Open AccessCryptic evolved melts beneath monotonous basaltic shield volcanoes in the Galápagos Archipelago
In this study the authors show that monotonous basaltic volcanoes can host a range of melts in their sub-volcanic systems, extending to rhyolitic compositions. The study implies that volcanoes which have produced monotonous basaltic lavas on long timescales could transition to more explosive, silica-rich eruptions in the future.
- Michael J. Stock
- , Dennis Geist
- & John Maclennan
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Article
| Open AccessFossilized solidification fronts in the Bushveld Complex argue for liquid-dominated magmatic systems
Magma storage zones are debated to either be crystal-dominated mush zones or large liquid-dominated magma chambers. Here, the authors discover fossilized solidification fronts of magnetitite in the Bushveld pluton, which indicate nucleation and crystal growth occurred at the magma chamber floor, precluding the existence of a thick crystal mush zone in this region.
- Willem Kruger
- & Rais Latypov
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Article
| Open AccessPolymorphism of feldspars above 10 GPa
Feldspars are stable at pressures up to 3 GPa along the mantle geotherm, but they can persist metastably at higher pressures at colder conditions. Here, above 10 GPa the authors find new high-pressure polymorphs of feldspars that could persist at depths corresponding to the Earth’s upper mantle, potentially influencing the dynamics and fate of cold subducting slabs.
- Anna Pakhomova
- , Dariia Simonova
- & Leonid Dubrovinsky
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Article
| Open AccessDeep CO2 in the end-Triassic Central Atlantic Magmatic Province
Many major mass extinction events have been associated with large volcanic eruption events, with the argument that large volumes of volcanic degassing could trigger past global climate changes. Here, the authors find that during the end-Triassic extinction event volcanic pulses emitted large amounts of CO2 comparable to projected anthropogenic emissions for the 21st century in the future 2 °C warming scenario.
- Manfredo Capriolo
- , Andrea Marzoli
- & Csaba Szabó
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Article
| Open AccessEvidence of metasomatism in the interior of Vesta
The authors here analyse the petrology of the meteorite NWA 8321 (parent body Vesta). They find sulfidation processes of olivine suggesting metasomatism in the Vestan interior and a partial melting origin for the host noritic diogenite.
- Ai-Cheng Zhang
- , Noriyuki Kawasaki
- & Hisayoshi Yurimoto
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Article
| Open AccessUncovering and quantifying the subduction zone sulfur cycle from the slab perspective
Sulfur is one of the key volatiles in Earth’s chemical cycles; however, sulfur speciation, isotopic composition, and flux during the subduction cycle remain unclear. Here, the authors provide direct constraints on subduction zone sulfur recycling from high-pressure rocks and explore implications for arc magmatism.
- Ji-Lei Li
- , Esther M. Schwarzenbach
- & Xin-Shui Wang
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Article
| Open AccessPrecise radiometric age establishes Yarrabubba, Western Australia, as Earth’s oldest recognised meteorite impact structure
The ~70 km-diameter Yarrabubba impact structure in Western Australia has previously been regarded as among Earth’s oldest meteorite craters, but has hitherto lacked absolute age constraints. Here, the authors determine a precise impact age of 2229 ± 5 Ma, which extends the terrestrial cratering record back in time by > 200 million years and establishes Yarrabubba as the oldest recognised meteorite impact structure on Earth.
- Timmons M. Erickson
- , Christopher L. Kirkland
- & Thomas M. Davison
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Article
| Open AccessGold endowments of porphyry deposits controlled by precipitation efficiency
Porphyry copper and gold deposits are the dominant natural suppliers of these metals to our society, yet the large variations in metal endowments of porphyry Cu–Au deposits remain obscure. Here, the author shows that Cu-rich porphyries require large amounts of magma and water to be formed, while Au-rich porphyries are the result of a better efficiency of Au precipitation.
- Massimo Chiaradia
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Article
| Open AccessMicrostructural constraints on magmatic mushes under Kīlauea Volcano, Hawaiʻi
Olivine crystals with prominent intracrystalline distortions have previously been used to quantify deformational processes within the mantle. Here, the authors show that similar techniques can be applied to deformed volcanic olivine crystals, providing quantitative constraints on the geometry of melt-rich mush piles within magmatic plumbing systems.
- Penny E. Wieser
- , Marie Edmonds
- & John Wheeler
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Article
| Open AccessCrystal scavenging from mush piles recorded by melt inclusions
The increasingly prevalent view of magmatic systems as mush-dominated challenges the common assumption that melt inclusions record the pre-eruptive storage and processing of the melts they were erupted with. Here, the authors show that melt inclusions from Kīlauea Volcano, Hawai'i exhibit extreme compositional diversity, consistent with the accumulation of inclusion-bearing crystals in magmatic mush zones for >170 years before their eventual eruption in unrelated carrier melts.
- Penny E. Wieser
- , Marie Edmonds
- & Barbara E. Kunz
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Article
| Open AccessSaline aqueous fluid circulation in mantle wedge inferred from olivine wetting properties
The authors here perform experiments to investigate the dihedral angle of olivine-H2O and olivine-H2O-NaCl systems. The observed effect of NaCl to decrease dihedral angles allows fluids to percolate through forearc mantle wedge and to accumulate in the overlying crust, accounting for the high electrical conductivity anomalies in forearc regions.
- Yongsheng Huang
- , Takayuki Nakatani
- & Catherine McCammon
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Article
| Open AccessGlobal geochemical fingerprinting of plume intensity suggests coupling with the supercontinent cycle
The links between plate tectonics and deep mantle structure remain unclear. Here, the authors demonstrate that transition elements (Ni, Cr, and Fe/Mn) in basaltic rocks can be used as a tool to trace plume-related magmatism through Earth history, and their results indicate the presence of a direct relationship between the intensity of plume magmatism and the supercontinent cycle.
- Hamed Gamal EL Dien
- , Luc S. Doucet
- & Ross Mitchell
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Article
| Open AccessCr-spinel records metasomatism not petrogenesis of mantle rocks
Chromian-spinel from mafic-ultramafic rocks is used as a reliable geotectonic and mantle melting indicator. Here, the authors argue that this only works partially – it can be used to assess information on mantle metasomatic processes but not petrogenesis.
- Hamed Gamal El Dien
- , Shoji Arai
- & Mohamed Hamdy
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Article
| Open AccessDiamond growth from organic compounds in hydrous fluids deep within the Earth
Diamonds can give us clues to the processes regulating deep carbon transport within the Earth. Here, the author discovers evidence from diamond coatings that organic compounds exist at great depth in Earth’s interior, and furthermore, that organic molecules may provide scaffolds for diamond nucleation and growth.
- Maria Luce Frezzotti
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Article
| Open AccessCompositional boundary layers trigger liquid unmixing in a basaltic crystal mush
This study seeks to tackle the question of why intermediate magmatic rock compositions are poorly represented on the Earth’s surface. The authors do so by tracking the evolution of the physical behaviour of immiscible Fe-rich liquids within a sample suite from the lava lake on the Kilauea Iki volcano, Hawaii.
- Victoria C. Honour
- , Marian B. Holness
- & Marlon M. Jean
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Article
| Open AccessMolybdenum systematics of subducted crust record reactive fluid flow from underlying slab serpentine dehydration
Fluid liberation and migration from subducted oceanic slabs play a critical role in arc magmatism but the volume and origin of the released fluids is unclear and difficult to trace. Here, the authors use Molybdenum isotope ratios to tackle these problems.
- Shuo Chen
- , Remco C. Hin
- & Tim Elliott
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Article
| Open AccessMetamorphic pressure variation in a coherent Alpine nappe challenges lithostatic pressure paradigm
The geodynamic evolution of mountain ranges can be reconstructed using the pressure recorded by minerals in metamorphic rocks, under the key assumption that rock pressure is lithostatic. Here, the authors challenge the lithostatic pressure paradigm by showing that there can be significant outcrop-scale pressure gradients due to compression- and reaction-induced stress.
- Cindy Luisier
- , Lukas Baumgartner
- & Torsten Vennemann
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Comment
| Open AccessFingerprinting metal transfer from mantle
The ore-forming magmas in post-subduction copper deposits are thought to be derived from the lower crust. The Au-Te fingerprints of post-subduction magmas reveal an important role for the metasomatized sub-crustal lithospheric mantle in the formation of porphyry and epithermal copper deposits.
- Zengqian Hou
- & Rui Wang
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Article
| Open AccessNorthward drift of the Azores plume in the Earth’s mantle
Tectonic plate motions are often reconstructed based on the assumption that mantle plumes are fixed within the mantle. Here, the authors provide geochemical and geodynamic evidence to suggest that the asymmetry of the Azores thermal anomaly can be explained by northward motion of the Azores plume.
- Maëlis Arnould
- , Jérôme Ganne
- & Xiaojun Feng
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Article
| Open AccessAncient recycled lower crust in the mantle source of recent Italian magmatism
Recycling of Earth’s crust through subduction and delamination contributes to mantle heterogeneity. Here, the authors measure coupled Sr-Nd-Pb isotope compositions of melt inclusions in Italian potassium-rich lavas, they suggest their results indicate a potential ancient lower crustal component in the mantle source.
- Janne M. Koornneef
- , Igor Nikogosian
- & Gareth R. Davies
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Perspective
| Open AccessThe causes of spatiotemporal variations in erupted fluxes and compositions along a volcanic arc
The primary causes of dramatic variations in volcanic flux and composition along strike in subduction zones remain largely unknown. Here we use a promising new approach to show that along-strike volcanic variability in the Quaternary Cascades Arc is primarily due to variations in the flux of basalt into the base of the crust, rather than crustal magma storage.
- C. B. Till
- , A. J. R. Kent
- & B. W. Pitcher
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Article
| Open AccessCarbon sequestration during core formation implied by complex carbon polymerization
The amount of carbon stored in closed hidden reservoirs is unknown. Here the authors use a computational approach to study the evolution of carbon species and observe polymerization of carbon atoms at high pressures, illustrating the potential for a significant carbon reservoir in the Earth’s deep interior.
- Natalia V. Solomatova
- , Razvan Caracas
- & Craig E. Manning
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Article
| Open AccessNb/Ta systematics in arc magma differentiation and the role of arclogites in continent formation
It is unclear why the crust among many arcs is so silica rich when there is a missing mafic component. Here the authors compile a global evaluation of Nb/Ta and examine xenoliths from Arizona to derive a model of why Nb/Ta fractionation is favored in the crust.
- Ming Tang
- , Cin-Ty A. Lee
- & Hehe Jiang
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Article
| Open AccessSulfide resorption during crustal ascent and degassing of oceanic plateau basalts
The solubility of sulfur in basaltic melt has important implications for the formation of magmatic ore deposits. Here, the authors show that magma ascent and sulfur-degassing influence the degree to which basaltic magmas are enriched in economically-important chalcophile and siderophile elements.
- C. D. J. Reekie
- , F. E. Jenner
- & H. M. Williams
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Article
| Open AccessAbiotic formation of condensed carbonaceous matter in the hydrating oceanic crust
Thermodynamic calculations suggest that condensed carbonaceous matter should be the dominant product of abiotic organic synthesis during serpentinization of the oceanic crust at Mid-Ocean Ridges. Here the authors report natural occurrences of such carbonaceous matter formed during low temperature alteration.
- Marie Catherine Sforna
- , Daniele Brunelli
- & Bénédicte Ménez
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Article
| Open AccessNo significant boron in the hydrated mantle of most subducting slabs
Boron is one of the main proxies for seawater-derived fluids in subduction zone volcanics and it is vital to characterise the location and concentration of boron in the oceanic lithosphere. Here the authors show that boron concentration in the mantle of downgoing slabs has been overestimated, because boron is strongly decoupled from water in the hydration process.
- Andrew M. McCaig
- , Sofya S. Titarenko
- & Samuele Agostini
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Article
| Open AccessMelting conditions in the modern Tibetan crust since the Miocene
Crustal melting may play a fundamental role in orogenic processes, but quantifying crustal melt remains difficult. Here, the authors combine pressure-temperature paths, electrical conductivity and geophysical data to elucidate the melting conditions in Tibet since the Miocene.
- Jinyu Chen
- , Fabrice Gaillard
- & Guillaume Richard