Featured
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| Open AccessYoung asteroidal fluid activity revealed by absolute age from apatite in carbonaceous chondrite
Chondritic meteorites formed in the early solar system and may tell us about primary processes at that time. Here, Zhang et al. report an absolute 207Pb/206Pb isochron age (4,450±50 Ma) of apatite from a carbonaceous chondrite constraining timing of fluid activity in meteorites.
- Ai-Cheng Zhang
- , Qiu-Li Li
- & Ru-Cheng Wang
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Article
| Open AccessSesquinary catenae on the Martian satellite Phobos from reaccretion of escaping ejecta
The origin of the numerous linear grooves and craters that litter the Martian moon Phobos' surface remains enigmatic. Here, by modelling low-velocity escaping ejecta from impacts to Phobos, the authors show that several of these chains can be explained by reimpacting sesquinary ejecta shortly after ejection.
- M. Nayak
- & E. Asphaug
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| Open AccessGeomagnetic reversal rates following Palaeozoic superchrons have a fast restart mechanism
The mechanism behind the initiation and termination of superchrons remains unclear. Here, the author provides insight into Palaeozoic superchrons, showing that the 10 million year interal adjacent to each superchron is characterized by asymmetry in reversal rates and unusually long duration chrons.
- Mark W. Hounslow
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Article
| Open AccessThe missing large impact craters on Ceres
Studying craters on atmosphere-less bodies can unlock information about planetesimal histories. Here, Marchi et al. present results from the NASA Dawn mission to Ceres showing that craters >100–150 km in size are largely absent, and find that Ceres’ internal evolution is responsible for their absence.
- S. Marchi
- , A. I. Ermakov
- & C. T. Russell
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Article
| Open AccessMultiple sulfur isotope evidence for massive oceanic sulfate depletion in the aftermath of Snowball Earth
Large positive sulphur isotope excursions, recorded in the wake of the Marinoan glaciation have previously been interpreted assuming stable ocean sulphate concentrations. Here, using multiple sulphur isotopes, the authors instead suggest significant ocean sulphate drawdown, driven by increased pyrite burial.
- Pierre Sansjofre
- , Pierre Cartigny
- & Magali Ader
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| Open AccessDetermining solar effects in Neptune’s atmosphere
The causes behind fluctuations in Neptune's brightness as observed from Earth have proved enigmatic. Here, Aplin and Harrison use photometric observations to show that solar ultraviolet radiation and galactic cosmic rays combined are responsible for the fluctuations originating in Neptune’s atmosphere.
- K. L. Aplin
- & R. G. Harrison
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Article
| Open AccessA new type of solar-system material recovered from Ordovician marine limestone
Meteorites falling on Earth today are believed to represent 100–150 parent bodies. Within 470 Myr ago sediments at a limestone quarry in Sweden, Schmitz et al. have found and identified a new type of meteorite based on chromium and oxygen isotopes sourced from a previously unknown parental body.
- B. Schmitz
- , Q. -Z. Yin
- & G. R. Huss
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Article
| Open AccessLasting mantle scars lead to perennial plate tectonics
The causes of intraplate deformation remain poorly constrained. Heron et al. use numerical models to show that ancient plate tectonic processes produce mantle lithosphere structures that may be reactivated to generate intraplate deformation.
- Philip J. Heron
- , Russell N. Pysklywec
- & Randell Stephenson
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Article
| Open AccessAn asteroidal origin for water in the Moon
Recent samples have shown that the Moon's interior, previously thought to be anhydrous, contains water, yet how this water was delivered is unclear. Here, using isotopic analyses and modelling, Barnes et al. show that carbonaceous chondrite-type objects delivered >80% of the Moon's bulk water.
- Jessica J. Barnes
- , David A. Kring
- & Sara S. Russell
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Article
| Open AccessPlate tectonics drive tropical reef biodiversity dynamics
Over a geological timescale, plate tectonics are thought to promote biodiversity, but this link remained descriptive. Here, Leprieur et al. model dynamically how plate tectonics shaped species diversification and movement of hotspots on tropical reefs over the past 140 million years.
- Fabien Leprieur
- , Patrice Descombes
- & Loïc Pellissier
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Article
| Open AccessConverging flow and anisotropy cause large-scale folding in Greenland's ice sheet
A range of mechanisms has been proposed for large-scale folding in polar ice sheets. Here, using new three-dimensional reconstructions of such folds in the onset region of the Greenland Petermann Glacier, the authors show that these formed due to flow convergence and the high mechanical anisotropy of ice.
- Paul D. Bons
- , Daniela Jansen
- & Ilka Weikusat
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Article
| Open AccessHot super-Earths stripped by their host stars
Theory predicts a deficit of super-Earth sized planets, which orbit close to their host star. Here, Lundkvist et al. use data from the NASA Kepler mission to show that this deficit is also seen in observations, thereby providing new insight into exoplanetary systems.
- M. S. Lundkvist
- , H. Kjeldsen
- & T. R. White
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| Open AccessMercury anomalies and the timing of biotic recovery following the end-Triassic mass extinction
The association between Central Atlantic Magmatic Province (CAMP) eruption volatiles and the end-Triassic mass extinction remains ambiguous. Here, the authors present mercury and palaeontological evidence from the same archive and show that significant biotic recovery did not begin until CAMP eruptions ceased.
- Alyson M. Thibodeau
- , Kathleen Ritterbush
- & Frank A. Corsetti
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Article
| Open AccessFormation of calcium sulfate through the aggregation of sub-3 nanometre primary species
The quantitative understanding of how gypsum nucleates and grows from aqueous solutions is limited. Here, the authors demonstrate how, by using truly in situ and fast time-resolved small-angle X-ray scattering, the four-stage solution-based nucleation and growth of this mineral can be quantified.
- Tomasz M. Stawski
- , Alexander E.S. van Driessche
- & Liane G. Benning
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Article
| Open AccessA potential hidden layer of meteorites below the ice surface of Antarctica
Collection data suggest the proportion of iron-based meteorites recovered from Antarctica is significantly lower than the rest of the world. Here, the authors propose a mechanism to explain this discrepancy, showing that iron meteorites heated by solar energy can move down through the ice, not to re-emerge.
- G. W. Evatt
- , M. J. Coughlan
- & I. D. Abrahams
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Article
| Open AccessTransition to a Moist Greenhouse with CO2 and solar forcing
Greenhouse-gas forcing has previously been thought to be rather ineffective at destroying the habitability of Earth-like planets. Here, the authors show that CO2is as effective as solar forcing at causing a climate transition to a Moist-Greenhouse regime and thus poses an equal threat to a planet's habitability.
- Max Popp
- , Hauke Schmidt
- & Jochem Marotzke
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Article
| Open AccessEvidence for link between modelled trends in Antarctic sea ice and underestimated westerly wind changes
Mechanisms responsible for the recent increase in Antarctic sea ice cover remain elusive. Here, the authors show that model underestimates of changes in wind-induced ocean circulation may contribute, in part, to the failure of CMIP5 models to accurately capture modern Antarctic sea ice trends.
- Ariaan Purich
- , Wenju Cai
- & Tim Cowan
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| Open AccessThe puzzling Venusian polar atmospheric structure reproduced by a general circulation model
Unlike some planets, the Venusian polar vortex is warmer than the mid-latitudes at cloud-top level, but the mechanism behind this is unknown. Here, the authors use a general circulation model and suggest the cold collar and warm polar regions are due to residual mean meridional circulation intensified by thermal tides.
- Hiroki Ando
- , Norihiko Sugimoto
- & Yoshihisa Matsuda
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| Open AccessComplex Greenland outlet glacier flow captured
Quantifying Greenland's future contribution to sea level requires accurate portrayal of its outlet glaciers in ice sheet simulations. Here, the authors show that outlet glacier flow can be captured if ice thickness is well constrained and vertical shearing as well as membrane stresses are included in the model.
- Andy Aschwanden
- , Mark A. Fahnestock
- & Martin Truffer
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| Open AccessEvidence for an ice shelf covering the central Arctic Ocean during the penultimate glaciation
The development of pan-Arctic Ocean ice shelves during peak glacials was proposed in the 1970s, an idea that has been disputed due to lack of evidence. Here, the authors present geophysical mapping data supporting the presence of such an ice shelf during the peak of the penultimate glaciation ∼140–160 ka.
- Martin Jakobsson
- , Johan Nilsson
- & Igor Semiletov
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Article
| Open AccessCorrelated compositional and mineralogical investigations at the Chang′e-3 landing site
The chemical compositions of young lava flows on the Moon have implications for late volcanism. Here, the authors present mineral distribution data from the Chang′e-3 Yutu rover in the northern Imbrium mare region, reporting unique compositional characteristics of a previously unsampled basalt type.
- Zongcheng Ling
- , Bradley L. Jolliff
- & Jianyu Wang
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Article
| Open AccessAerosol influence on energy balance of the middle atmosphere of Jupiter
Aerosols play an important role in Earth’s radiative balance, but their influence on the climate of giant planets is unclear. Here, the authors show that gases alone cannot maintain the energy balance in the middle atmosphere of Jupiter, instead proposing that an aerosol layer dominates radiative heating.
- Xi Zhang
- , Robert A. West
- & Yuk L. Yung
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Article
| Open AccessCarbon-depleted outer core revealed by sound velocity measurements of liquid iron–carbon alloy
The composition of the Earth's core, particularly the light elements present, is not well constrained. Here, the authors report sound velocities of liquid iron-carbon alloy as measured at very high pressures using inelastic X-ray scattering and suggest that carbon cannot be predominant in the outer core.
- Yoichi Nakajima
- , Saori Imada
- & Alfred Q. R. Baron
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Article
| Open AccessTracing the fate of carbon and the atmospheric evolution of Mars
Mars likely evolved from a warmer, wetter early state to the cold, arid current climate, but this evolution is not reflected in recent observations and measurements. Here, the authors derive quantitative constraints on the atmospheric pressure through time, identifying a mechanism that explains the carbon data.
- Renyu Hu
- , David M. Kass
- & Yuk L. Yung
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| Open AccessThe dune effect on sand-transporting winds on Mars
The absence of in situand long-term meteorological data hampers our understanding of wind movement on Mars. Here, the authors use 3D airflow modelling to investigate small scale ripple migration and suggest that local dune topography exerts a strong influence on wind speed and direction.
- Derek W. T. Jackson
- , Mary C Bourke
- & Thomas A. G. Smyth
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| 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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| Open AccessThe deuterium/hydrogen distribution in chondritic organic matter attests to early ionizing irradiation
The insoluble organic matter in primitive carbonaceous chondrites has a systematic large enrichment in deuterium and several hypotheses have been proposed to explain this. Here, the authors demonstrate that irradiation from the protosun could quantitatively explain the deuteration.
- Boris Laurent
- , Mathieu Roskosz
- & Jean-Marc Lefebvre
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| Open AccessReconstructing the transport history of pebbles on Mars
The discovery of rounded pebbles by Curiosity suggests sustained fluvial activity existed on Mars, but interpretations have been qualitative. Here, the authors show that transport distance can be calculated on the basis of pebble shape alone, suggesting they travelled 10 s of km by bed-load transport.
- Tímea Szabó
- , Gábor Domokos
- & Douglas J. Jerolmack
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| Open AccessCosmochemical fractionation by collisional erosion during the Earth’s accretion
Collisions in the early Solar System affected the final composition of the terrestrial planets, and enstatite chondrites (EC) are thought to represent the primordial Earth’s precursors. Here, the authors show that differences between Earth and EC are due to impact erosion of >15% of the early Earth’s mass.
- Asmaa Boujibar
- , Denis Andrault
- & Julien Monteux
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Article
| Open AccessExtensive volatile loss during formation and differentiation of the Moon
Recent studies suggest that the Moon is not as volatile-poor as once thought, and that volatile elements should be concentrated in crustal materials. Here, the authors present Zn isotopic and abundance data as evidence of evaporative loss of volatiles during formation of the Moon, supporting alternative models.
- Chizu Kato
- , Frederic Moynier
- & James M.D. Day
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| Open AccessEarth-like aqueous debris-flow activity on Mars at high orbital obliquity in the last million years
It is thought that water flowed on the surface of Mars in the geological past during periods of high orbital obliquity. Here, the authors assess how much liquid water was present and suggest that debris flows occurred at Earth-like frequencies during high-obliquity periods in the past million years.
- T. de Haas
- , E. Hauber
- & M. G. Kleinhans
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Article
| Open AccessUsing the transit of Venus to probe the upper planetary atmosphere
The atmosphere of a transiting planet shields the stellar radiation enabling size and density stratification to be estimated. Here, the authors study Venus and show that the measured radius depends on the wavelength used, which has implications for Venus’s ionosphere and may help in planning future missions.
- Fabio Reale
- , Angelo F. Gambino
- & Giuseppe Piccioni
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Early aqueous activity on the ordinary and carbonaceous chondrite parent bodies recorded by fayalite
The parent bodies of many chondritic meteorites experienced aqueous alteration, the chronology of which helps constrain their histories. Here, the authors synthesize a fayalite standard and report reliable ages of secondary fayalite, from which model accretion ages are determined and the place of accretion is inferred.
- Patricia M. Doyle
- , Kaori Jogo
- & Ian D. Hutcheon
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| Open AccessEvidence for methane in Martian meteorites
Extremophiles on Earth are known to respire methane, and the potential existence of methane on Mars indicates similar organisms could survive there. Here, the authors present data from Martian meteorites confirming the presence of methane, indicating that a habitat capable of supporting organisms exists on Mars.
- Nigel J. F. Blamey
- , John Parnell
- & Roberta L. Flemming
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Article
| Open AccessUbiquity of Kelvin–Helmholtz waves at Earth’s magnetopause
Although magnetic reconnection is recognized as the dominant mode for solar wind plasma to enter the magnetosphere, Kelvin–Helmholtz waves (KHW) have been suggested to also be involved. Here, the authors use 7 years of THEMIS data to show that KHW occur 19% of the time, and may be important for plasma transport.
- Shiva Kavosi
- & Joachim Raeder
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Article
| Open AccessThe solar magnetic activity band interaction and instabilities that shape quasi-periodic variability
The origins of the Sun’s periodic activity, such as sunspot cycles, are poorly understood. McIntosh et al.posit that the rotational forcing of the activity bands comprising the 22-year magnetic cycle undergoes shorter-term variations, driving magnetic flux surges that impact solar output on those timescales.
- Scott W. McIntosh
- , Robert J. Leamon
- & Roger K. Ulrich
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Bidecadal North Atlantic ocean circulation variability controlled by timing of volcanic eruptions
While present in palaeoclimate records, the drivers behind 20-year climate variability are poorly understood. Here, using climate simulations and in situand palaeo data, the authors present a possible link between volcanic eruptions, Great Salinity Anomalies and the Atlantic overturning circulation.
- Didier Swingedouw
- , Pablo Ortega
- & Roland Séférian
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Cracks in Martian boulders exhibit preferred orientations that point to solar-induced thermal stress
Many rock cracks on Earth point north, suggesting that the Sun may be involved in their formation. Here, the authors compile this Earth data, collect similar data for rock cracks on Mars, and present modelling results, linking the origin of Mars rock cracks to thermal stress from the Sun.
- Martha-Cary Eppes
- , Andrew Willis
- & Beibei Zhou
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Article
| Open AccessUpward electrical discharges observed above Tropical Depression Dorian
Upward electrical discharges from thunderstorms were discovered recently, and only a very limited set of observations exist because they are rare and unpredictable. Here, the authors present recordings of different types of the discharge above a storm, which contradict current theories of their origins.
- Ningyu Liu
- , Nicholas Spiva
- & Steven A. Cummer
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Article |
Nanoscale infrared spectroscopy as a non-destructive probe of extraterrestrial samples
Infrared spectral mapping offers the non-destructive analyses of samples; however, the spatial resolution is restricted to >10 microns. Here, the authors present a new infrared technique capable of sub-micron scale mineral identification, demonstrated using a chondrule and a cometary dust grain.
- Gerardo Dominguez
- , A. S. Mcleod
- & D. N. Basov
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Article
| Open AccessPressure–temperature evolution of primordial solar system solids during impact-induced compaction
Collisions between primordial planetesimals led to the formation of our asteroids and meteorites. Here, the authors use modelling to explore the compaction of planetsimals, tracking how pressure, temperature and porosity may have varied during the impacts, helping interpret early Solar System processes.
- P. A. Bland
- , G. S. Collins
- & J. Moore
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Lonsdaleite is faulted and twinned cubic diamond and does not exist as a discrete material
Lonsdaleite has been used as a marker of asteroid impacts and is thought to have mechanical properties superior to diamond; however, pure lonsdaleite has not been described or fabricated. Here, the authors show that it does not exist as a discrete material and is in fact faulted and twinned cubic diamond.
- Péter Németh
- , Laurence A. J. Garvie
- & Peter R. Buseck
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Article
| Open AccessMissing driver in the Sun–Earth connection from energetic electron precipitation impacts mesospheric ozone
Energetic electron precipitation (EEP) from the Earth's outer radiation belt can lead to ozone loss in the mesosphere, yet long-term variability has not been quantified. Here, the authors present satellite observations and show that on solar cycle timescales EEP causes ozone to vary by up to 34%.
- M. E. Andersson
- , P. T. Verronen
- & A. Seppälä
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Determining volcanic eruption styles on Earth and Mars from crystallinity measurements
Although observations of volcanic deposits on Mars are more accessible than ever, constraining Martian eruption styles remains a challenge. Here, the authors show that volcanic eruption style can be characterized through X-ray diffraction analysis of groundmass crystallinity in basaltic volcanic deposits.
- Kellie T. Wall
- , Michael C. Rowe
- & Jennifer D. Eccles
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Threshold for sand mobility on Mars calibrated from seasonal variations of sand flux
Although the Martian landscape presents evidence of wind erosion, sand-moving winds on Mars were thought to be rare due to the thin atmosphere. Here, the authors show that sand transport occurs daily and that the resulting sand flux varies seasonally.
- F. Ayoub
- , J.-P. Avouac
- & N.T. Bridges
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Impact-induced shock and the formation of natural quasicrystals in the early solar system
The first-reported natural quasicrystal, found in the meteorite Khatyrka, has posed many questions regarding the extraterrestrial processes that led to its formation. Here, the authors suggest how the metallic Al- and Cu-bearing phases formed and report the discovery of other new minerals.
- Lincoln S. Hollister
- , Luca Bindi
- & Paul J. Steinhardt
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Frictional velocity-weakening in landslides on Earth and on other planetary bodies
Despite commonly occurring on Earth and other terrestrial bodies, mass wasting processes are poorly understood, hampering hazard assessment and mitigation. Lucas and colleagues propose a universal velocity-weakening friction law capable of describing the behaviour of small to large landslides.
- Antoine Lucas
- , Anne Mangeney
- & Jean Paul Ampuero
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Discovery of the action of a geophysical synchrotron in the Earth’s Van Allen radiation belts
The processes influencing the Van Allen belt – a layer of charged particles inside the Earth’s magnetosphere – are poorly understood. Using CRRES and NASA’s Van Allen Probes data, Mann et al.suggest that ultra-low frequency waves may play a larger role in accelerating particles than previously thought.
- Ian R. Mann
- , E. A. Lee
- & F. Honary
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| Open AccessRapid regional perturbations to the recent global geomagnetic decay revealed by a new Hawaiian record
The Earth’s geomagnetic field has weakened in recent centuries, leading to calls for historic reconstructions; however, records are sparse and unevenly distributed. de Groot et al.provide a new, high-quality record from Hawaiian lavas, revealing crucial insights into past geomagnetic field fluctuations.
- L. V. de Groot
- , A. J. Biggin
- & E. Herrero-Bervera
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