Featured
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Article
| Open AccessSublimation of terrestrial permafrost and the implications for ice-loss processes on Mars
Sublimation of ice is believed to have generated a variety of landforms on Mars and other planetary bodies. Here the authors show the first long-term in situ effective diffusion coefficient of terrestrial ice-free loess (Mars analog soil), scaled to Mars average pressure, temperature and CO2 atmosphere.
- Thomas A. Douglas
- & Michael T. Mellon
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Article
| Open AccessFast negative breakdown in thunderstorms
Recent studies have shown that lightning is initiated by a newly-recognized discharge process called fast positive breakdown. Here, the authors present observational evidence of fast breakdown but of negative polarity, seemingly contrary to current understanding of discharge physics.
- Julia N. Tilles
- , Ningyu Liu
- & Jennifer Wilson
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Article
| Open AccessThe operational environment and rotational acceleration of asteroid (101955) Bennu from OSIRIS-REx observations
Vicinity of small bodies might be dangerous to the spacecrafts and to their instrumentation. Here the authors show the operational environment of asteroid Bennu, validate its photometric phase function and demonstrate the accelerating rotational rate due to YORP effect using the data acquired during the approach phase of OSIRIS-REx mission.
- C. W. Hergenrother
- , C. K. Maleszewski
- & B. Marty
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Article
| Open AccessEvidence for igneous differentiation in Sudbury Igneous Complex and impact-driven evolution of terrestrial planet proto-crusts
It remains controversial whether or not impact melt sheets produced by asteroid impacts were able to undergo large-scale igneous differentiation. Here the authors present evidence for large igneous differentiation in one of these sheets and argue that this process has contributed to the evolution and lithological diversity of the proto-crusts on terrestrial planets.
- Rais Latypov
- , Sofya Chistyakova
- & Hannu Huhma
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Article
| Open Access2600-years of stratospheric volcanism through sulfate isotopes
The estimation of volcanic contribution to climate variability requires identification of global-scale eruptions. Here the authors present a new 2600-year chronology of stratospheric volcanic events that relies on isotopic signature of ice core sulfate, that improves ice core volcanic reconstruction.
- E. Gautier
- , J. Savarino
- & J. Farquhar
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Article
| Open AccessMercury’s anomalous magnetic field caused by a symmetry-breaking self-regulating dynamo
A new regime of planetary magnetic fields was revealed through the MESSENGER spacecraft mission to Mercury. Here, the authors present a numerical dynamo model that can re-produce both the axisymmetric and anomalously axially offset dipolar magnetic field of Mercury.
- Futoshi Takahashi
- , Hisayoshi Shimizu
- & Hideo Tsunakawa
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Article
| Open AccessPlanetary-scale streak structure reproduced in high-resolution simulations of the Venus atmosphere with a low-stability layer
A planetary-scale streak structure in the Venusian lower-cloud layer was observed by the Akatsuki orbiter. Here the authors present numerical simulations that reproduce such structure and reveal that a low-stability layer, which induces baroclinic disturbances, is essential for its formation.
- Hiroki Kashimura
- , Norihiko Sugimoto
- & Yoshi-Yuki Hayashi
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Article
| Open AccessFormation of electron radiation belts at Saturn by Z-mode wave acceleration
Radial diffusion is the only mechanism considered to accelerate trapped electrons to relativistic energies in Saturn’s magnetic field, forming radiation belts. Here the authors show another mechanism, electron acceleration via Doppler shifted cyclotron resonant interaction with Z-mode waves, which can form radiation belts inside the orbit of Enceladus.
- E. E. Woodfield
- , R. B. Horne
- & W. S. Kurth
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Article
| Open AccessMartian magmatism from plume metasomatized mantle
A unified model for the formation of martian rock types is required to understand Mars’s formation and evolution. Here the authors show that nakhlite and chassignite meteorites originate from melting of metasomatized depleted mantle lithosphere, whereas shergottite melts originate from deep plume sources.
- James M. D. Day
- , Kimberly T. Tait
- & Clive R. Neal
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Article
| Open AccessGlobal-scale control of extensional tectonics on CO2 earth degassing
Earth degassing of CO2-rich fluids contributes significantly to the global carbon budget but its link to tectonic regimes remains unclear. Here, the authors use global geological datasets to show that there is a positive spatial correlation between CO2 discharges and extensional tectonic regimes.
- Giancarlo Tamburello
- , Silvia Pondrelli
- & Dmitri Rouwet
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Article
| Open AccessReduction spheroids preserve a uranium isotope record of the ancient deep continental biosphere
Red beds contain reduction spheroids that formed underground millions of years ago and whose origin remains poorly constrained. Here the authors use uranium isotopes to identify ancient fingerprints of bacteria in these features, confirming that they were produced by subsurface life in the geological past.
- Sean McMahon
- , Ashleigh v. S. Hood
- & Stephen Bowden
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Article
| Open AccessThe reaction of hydroxyl and methylperoxy radicals is not a major source of atmospheric methanol
The reaction of hydroxyl and methylperoxy radicals has recently been suggested as the source of missing methanol in the remote troposphere. Here, the authors present direct experimental measurements demonstrating the reaction leads to further underprediction of modelled methanol.
- Rebecca L. Caravan
- , M. Anwar H. Khan
- & Craig A. Taatjes
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Article
| Open AccessEvidence for magmatic carbon bias in 14C dating of the Taupo and other major eruptions
Correlations between prehistoric eruptions and other phenomena depend on accurate dating of the eruption. Here the authors show that magmatic CO2 in groundwater can bias radiocarbon ages for eruptions and that plateaux of carbon isotopic values in tree ring sequences biased by magmatic CO2 foreshadow major eruptions.
- Richard N. Holdaway
- , Brendan Duffy
- & Ben Kennedy
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Article
| Open AccessElectrical conductivity and magnetic dynamos in magma oceans of Super-Earths
With the discovery of large rocky exoplanets called Super-Earths, questions have arisen regarding the properties of their interiors and their ability to produce a magnetic field. Here, the authors show that under high pressure, molten silicates are semi-metallic and that magma oceans would host a dynamo process.
- François Soubiran
- & Burkhard Militzer
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Article
| Open AccessThe shape of watersheds
River networks worldwide follow the emblematic Hack’s Law, which expresses the length of a stream as a function of its watershed area. Here the authors show this law does not depend on lithology or rainfall, but on the shape of watersheds and confirms the self-similarity of river networks.
- Timothée Sassolas-Serrayet
- , Rodolphe Cattin
- & Matthieu Ferry
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Review Article
| Open AccessEvaluating climate geoengineering proposals in the context of the Paris Agreement temperature goals
Research and debate are intensifying on complementing CO2 emissions reductions with hypothetical climate geoengineering techniques. Here, the authors assess their potentials, uncertainties and risks, and show that they cannot yet be relied on to significantly contribute to meeting the Paris Agreement temperature goals.
- Mark G. Lawrence
- , Stefan Schäfer
- & Jürgen Scheffran
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Article
| Open AccessLess absorbed solar energy and more internal heat for Jupiter
Radiant energy budgets and internal heat play a key role in the evolution of planets. Here, the authors analyze data from the Cassini mission to show that Jupiter’s radiant energy and internal heat budgets are significantly larger than previous estimates.
- Liming Li
- , X. Jiang
- & R. W. Schmude Jr.
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Article
| Open AccessA hexagon in Saturn’s northern stratosphere surrounding the emerging summertime polar vortex
The Cassini spacecraft has provided an unprecedented characterisation of seasonal changes on Saturn. Here the authors describe the development of a warm polar vortex in Saturn’s northern summer, and show that the hexagon extends hundreds of kilometres from the troposphere into the stratosphere.
- L. N. Fletcher
- , G. S. Orton
- & S. B. Calcutt
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Article
| Open AccessSolar superstorm of AD 774 recorded subannually by Arctic tree rings
Tree rings retain information of sudden variations of ancient radiocarbon (14C) content, however the origin and exact timing of these events often remain uncertain. Here, the authors analyze a set of Arctic tree rings and link a rapid increase in 14C to a solar event that occurred during the spring of AD 774.
- J. Uusitalo
- , L. Arppe
- & M. Oinonen
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Article
| Open AccessStrong whistler mode waves observed in the vicinity of Jupiter’s moons
Observations of Jupiter’s magnetosphere provide opportunities to understand how magnetic fields interact with particles. Here, the authors report that the chorus wave power is increased in the vicinity of Europa and Ganymede. The generated waves are able to accelerate particles to very high energy.
- Y. Y. Shprits
- , J. D. Menietti
- & D. A. Gurnett
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Article
| Open AccessSilica-rich volcanism in the early solar system dated at 4.565 Ga
Achondritic meteorites can record volcanism and crust formation on planetesimals in the early Solar System. Here, the authors date the Northwest Africa 11119 meteorite with an Al-Mg age of 4564.8 ± 0.3 Ma indicating that this is the earliest evidence of silicic volcanism in the Solar System to date.
- Poorna Srinivasan
- , Daniel R. Dunlap
- & Francis M. McCubbin
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Article
| Open AccessTransient marine euxinia at the end of the terminal Cryogenian glaciation
The termination of the Marinoan snowball Earth event marks one of the most drastic transitions in Earth history, but the oceanic response remains unclear. Here, the authors’ integrated analysis demonstrates that the ocean experienced transient but widespread euxinia following this Snowball Earth event.
- Xianguo Lang
- , Bing Shen
- & Haoran Ma
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Article
| Open AccessThe Medusae Fossae Formation as the single largest source of dust on Mars
Martian dust is globally enriched in S and Cl and has a distinct mean S:Cl ratio. Here the authors identify that the largest potential source region for Martian dust based on analysis of elemental abundance data may be the Medusae Fossae Formation.
- Lujendra Ojha
- , Kevin Lewis
- & Mariek Schmidt
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Article
| Open AccessObservation of nuclear quantum effects and hydrogen bond symmetrisation in high pressure ice
Hydrogen atoms in water ices, under pressures at which they might exist in ocean exoplanets and icy moons, exhibit dynamics that are still poorly understood. Here, 1H-NMR experiments approaching the Mbar range shed light on the symmetrisation of hydrogen bonds preceding and accompanying the transformation of ice VII into ice X.
- Thomas Meier
- , Sylvain Petitgirard
- & Leonid Dubrovinsky
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Article
| Open AccessStrong plates enhance mantle mixing in early Earth
The subducting plates can either penetrate straight into the lower mantle or flatten in the mantle transition zone, yet slab dynamics in the past remains unclear. Here, using subduction models, the authors predict that a hotter early Earth was probably more favourable to lower mantle slab penetration.
- Roberto Agrusta
- , Jeroen van Hunen
- & Saskia Goes
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Article
| Open AccessReconstructing the sediment concentration of a giant submarine gravity flow
Giant submarine gravity flows are a key mechanism in global sediment transport, yet their properties remain enigmatic. Here, the authors reconstruct the properties of a historic giant submarine gravity flow from deposits across the seafloor.
- Christopher John Stevenson
- , Peter Feldens
- & David Mosher
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Correspondence
| Open AccessOn the origin of molecular oxygen in cometary comae
- K. L. Heritier
- , K. Altwegg
- & E Vigren
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Correspondence
| Open AccessReply to “On the origin of molecular oxygen in cometary comae”
- Y. Yao
- & K. P. Giapis
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Article
| Open AccessExtremely strong polarization of an active asteroid (3200) Phaethon
(3200) Phaethon is a near-Earth asteroid discovered in 1983 that has large inclination and eccentricity. Here, the authors perform polarimetric observation of Phaethon over a wide range of solar phase angle and report that the asteroid exhibits a very strong linear polarization.
- Takashi Ito
- , Masateru Ishiguro
- & Kiyoshi Kuramoto
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Article
| Open AccessGlobally asynchronous sulphur isotope signals require re-definition of the Great Oxidation Event
The Great Oxidation Event (GOE) is considered to have occurred at 2.33–2.32 Ga based on the last occurrence of MIF-S in South Africa. Here, based on sulphur isotope analysis of samples from Western Australia, the authors show preservation of MIF-S beyond 2.31 Ga and call for a re-evaluation of GOE timing.
- Pascal Philippot
- , Janaína N. Ávila
- & Vincent Busigny
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Article
| Open AccessMimicking the surface and prebiotic chemistry of early Earth using flow chemistry
There is still much debate on early Earth geochemical conditions affecting the chemistry of simple synthons that originated life. Here, the authors report an uninterrupted multistep synthetic route to 2-aminooxazole by means of flow chemistry equipment, mimicking a plausible early Earth (geo)chemical scenario.
- Dougal J. Ritson
- , Claudio Battilocchio
- & John D. Sutherland
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Article
| Open AccessPersistent multi-scale fluctuations shift European hydroclimate to its millennial boundaries
In recent years, there has been an ongoing discussion about the hydroclimatic changes over Europe. Here, the authors show that since the beginning of the 20th century, hydroclimatic conditions have shifted to their millennial boundaries, remaining at these extreme levels for a period of unprecedented duration.
- Y. Markonis
- , M. Hanel
- & E. R. Cook
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Article
| Open AccessRecent strengthening of the stratospheric Arctic vortex response to warming in the central North Pacific
The stratospheric Arctic vortex plays a critical role in forecasting cold winters in northern mid-latitudes. Here the authors show that the stratospheric Arctic vortex strengthened during 1998–2016, with ~25% of this strengthening contributed by warming in the central North Pacific.
- Dingzhu Hu
- , Zhaoyong Guan
- & Rongcai Ren
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Article
| Open AccessA large planetary body inferred from diamond inclusions in a ureilite meteorite
Ureilites are a type of meteorite that are believed to be derived from a parent body that was impacted in the early solar system. Here, the authors analyse inclusions within diamonds from a ureilite meteorite and find that they must have formed at above 20 GPa suggesting the parent body was Mercury- to Mars-sized.
- Farhang Nabiei
- , James Badro
- & Philippe Gillet
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Article
| Open AccessNumerical simulations of a kilometre-thick Arctic ice shelf consistent with ice grounding observations
Ice grounding features discovered in the Arctic Basin, in water depths exceeding 1 km and dated to the penultimate glacial, suggest a past Arctic ice shelf. Here, the authors undertake numerical simulations that shed light on how such an ice shelf could have formed, its dynamics and most likely configuration.
- Edward G. W. Gasson
- , Robert M. DeConto
- & Chris D. Clark
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Article
| Open AccessShallow magma diversions during explosive diatreme-forming eruptions
Shallow magmatic feeder systems in monogenetic volcanic fields may determine how a volcano erupts. Here, the authors use numerical modeling to show that explosive excavation and infilling of eruptive craters affects local stress states, with feedbacks controlling sites and depths of crater-forming explosions.
- Nicolas Le Corvec
- , James D. Muirhead
- & James D. L. White
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Article
| Open AccessThe world’s largest High Arctic lake responds rapidly to climate warming
Arctic ecosystems are at threat due to the rapid nature of climate change and Arctic amplification. Here, the authors show that the watershed of Lake Hazen, the Arctic’s largest lake by volume, has undergone dramatic changes in response to as little as a ~1°C increase in summer air temperatures.
- Igor Lehnherr
- , Vincent L. St. Louis
- & Charles H. Talbot
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Article
| Open AccessThe oldest magnetic record in our solar system identified using nanometric imaging and numerical modeling
Magnetic fields are thought to have been influential in the formation of our solar system. Here, the authors observe thermomagnetically stable, non-uniformly magnetized kamacite grains within chondritic meteorites, and calculate the grains to retain recordings of these magnetic fields.
- Jay Shah
- , Wyn Williams
- & Rafal E. Dunin-Borkowski
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Article
| Open AccessA b map implying the first eastern rupture of the Nankai Trough earthquakes
Earthquakes generated from the Nankai Trough have caused much devastation over the years. Here, the authors present a b-value map for the Nankai Trough zone, where the Eastern part of the trough has lower b-values than the West, which may help to explain why the Eastern part tends to rupture first.
- K. Z. Nanjo
- & A. Yoshida
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Article
| Open AccessDark zone of the Greenland Ice Sheet controlled by distributed biologically-active impurities
The surface types that comprise the dark zone of the Greenland Ice Sheet, an area of bare ice with low albedo, are unknown. Here, the authors use UAV imagery to show that, during the melt-season, biologically active surface impurities are responsible for spatial albedo patterns and the dark zone itself.
- Jonathan C. Ryan
- , Alun Hubbard
- & Jason Box
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Article
| Open AccessA light carbon isotope composition for the Sun
The Sun’s light stable isotopes compositions can help us understand how our solar system formed. Here, the authors find that solar C is depleted relative to bulk Earth indicating that the 13C enrichment of the terrestrial planets is from CO self-shielding or inheritance from the parent cloud.
- James R. Lyons
- , Ehsan Gharib-Nezhad
- & Thomas R. Ayres
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Article
| Open AccessBiological methane production under putative Enceladus-like conditions
Many methanogenic archaea use H2 and CO2 to produce methane. Here, Taubner et al. show that Methanothermococcus okinawensis produces methane under conditions extrapolated for Saturn’s icy moon, Enceladus, and estimate that serpentinization may produce sufficient H2 for biological methane production.
- Ruth-Sophie Taubner
- , Patricia Pappenreiter
- & Simon K.-M. R. Rittmann
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Article
| Open AccessSolar system expansion and strong equivalence principle as seen by the NASA MESSENGER mission
The NASA MESSENGER mission collected a rich dataset enabling determination of Mercury’s ephemeris. Here, the authors analyse MESSENGER data obtained over an extended period of time to quantify parameters related to General Relativity.
- Antonio Genova
- , Erwan Mazarico
- & Maria T. Zuber
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Article
| Open AccessIron diapirs entrain silicates to the core and initiate thermochemical plumes
During planetary formation segregation of an iron core from rocky silicates takes place. Here, the authors use analogue fluid experiments show that iron diapirs entrain volatiles and silicates to the Earth’s core and initiate buoyant thermochemical plumes to reoxidize and hydrate the upper mantle and atmosphere.
- J. R. Fleck
- , C. L. Rains
- & P. L. Olson
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Article
| Open AccessTiming and pacing of the Late Devonian mass extinction event regulated by eccentricity and obliquity
Understanding of Late Devonian mass extinction mechanisms is poor due to imprecise stratigraphies. Here, using cyclostratigraphic techniques, the authors present a global orbitally-calibrated chronology and reveal the key role of astronomically-forced Milankovitch climate change.
- David De Vleeschouwer
- , Anne-Christine Da Silva
- & Philippe Claeys
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Article
| Open AccessSolving for ambiguities in radar geophysical exploration of planetary bodies by mimicking bats echolocation
Radar sounders, used for the geophysical exploration of celestial objects in the solar system, possess striking similarities to bat sonars. Here, the authors adapt and implement the bat clutter mitigation mechanism to radar geophysical exploration of planetary bodies.
- Leonardo Carrer
- & Lorenzo Bruzzone
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Article
| Open AccessExperimental evidence supporting a global melt layer at the base of the Earth’s upper mantle
A 56–60 km thick low velocity layer exists at the base of the Earth’s upper mantle. Here, the authors experimentally reproduced the wadsleyite-to-olivine transition in the upwelling mantle and show that the low velocity anomaly can be explained by melting of hydrous peridotite.
- D. Freitas
- , G. Manthilake
- & D. Andrault
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Article
| Open AccessImpact-induced changes in source depth and volume of magmatism on Mercury and their observational signatures
Mantle partial melting produced the volcanic crust of Mercury. Here, the authors numerically model the formation of post-impact melt sheets and find that mantle convection was weak at around 3.7–3.8 Ga and that the melt sheets of Caloris and Rembrandt may contain partial melting of pristine mantle material.
- Sebastiano Padovan
- , Nicola Tosi
- & Thomas Ruedas
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