Planetary science

  • Article
    | Open Access

    River beds often exhibit armouring, in which formation of a coarse surface layer shields the finer underlying grains from erosion. Here, using experiments in a laboratory river and discrete and continuum models, the authors demonstrate that river-bed armouring is driven by vertical granular segregation.

    • Behrooz Ferdowsi
    • , Carlos P. Ortiz
    •  & Douglas J. Jerolmack
  • Article
    | Open Access

    Snowball Earth glaciations were some of the most extreme climate events in Earth history, and are temporally linked to major biogeochemical changes. Here, using geochemical proxies, the authors show that during the Marinoan glaciation, there was likely open water, active oxygen production, and nitrogen cycling.

    • Benjamin W. Johnson
    • , Simon W. Poulton
    •  & Colin Goldblatt
  • Article
    | Open Access

    In the Gale Crater on Mars, organic matter has been detected, but in much lower concentrations than expected. Here, the authors conduct clay mineral synthesis experiments which suggest that clay minerals may rapidly form under oxidized conditions and thus explain the low organic concentrations in Gale Crater.

    • Seth R. Gainey
    • , Elisabeth M. Hausrath
    •  & Courtney L. Bartlett
  • Article
    | Open Access

    Downslope sediment transport on Mars is reported, but the transport capacity of unstable water under low pressures is not well understood. Here, the authors present a newly discovered, highly reactive transportation mechanism that is only possible under low pressure environments.

    • Jan Raack
    • , Susan J. Conway
    •  & Manish R. Patel
  • Article
    | Open Access

    The impact of volcanism on ice sheet melting during the last deglaciation is poorly understood and limited by a lack of suitable proxies. Here, the authors combine annually resolved records of ice sheet melting with numerical models to show that ice sheets are sensitive to high-latitude volcanic eruptions.

    • Francesco Muschitiello
    • , Francesco S. R. Pausata
    •  & Barbara Wohlfarth
  • Article
    | Open Access

    Despite dramatic changes in carbon sinks, severe Snowball Earth glaciations have not occurred since the Cryogenian. Here, via the measurement of global subduction zone lengths and carbon cycle modelling, the authors show that a two fold increase in volcanic CO2 input likely thwarted global glaciation.

    • Benjamin J. W. Mills
    • , Christopher R. Scotese
    •  & Timothy M. Lenton
  • Article
    | Open Access

    A paucity of natural archives can make resolving rapid ocean rises induced by ice-sheet collapses during past periods of warming difficult. Here the authors show that systematic and common coralgal terraces record punctuated sea level rise events over decades to centuries during the last deglaciation.

    • Pankaj Khanna
    • , André W. Droxler
    •  & Thomas C. Shirley
  • Article
    | Open Access

    Sulphate-rich sediments have been taken as evidence of surface water on Mars. Here, the authors show that cryo-concentrated brines chemically weather olivine minerals forming sulfate minerals at up to −60 °C, showing that cryogenic weathering and sulfate formation can occur under current Martian conditions.

    • Paul B. Niles
    • , Joseph Michalski
    •  & D. C. Golden
  • Article
    | Open Access

    Significant amounts of different perchlorate salts have been discovered on the surface of Mars. Here, the authors show that magnesium perchlorate has a major impact on water structure in solution, providing insight into how an aqueous fluid might exist under the sub-freezing conditions present on Mars.

    • Samuel Lenton
    • , Natasha H. Rhys
    •  & Lorna Dougan
  • Article
    | Open Access

    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
  • Article
    | Open Access

    Mars hosts the solar system’s largest volcanoes, but their formation rates remain poorly constrained. Here, the authors have measured the crystallization and ejection ages of meteorites from a Martian volcano and find that its growth rate was much slower than analogous volcanoes on Earth.

    • Benjamin E. Cohen
    • , Darren F. Mark
    •  & Caroline L. Smith
  • Article
    | Open Access

    The Dawn spacecraft has provided orbital bistatic radar observations of a small body in the solar system. Here, the authors present results from Vesta suggesting that smooth terrains with heightened hydrogen concentrations indicate that ground-ice presence potentially helped shape Vesta’s current surface texture.

    • Elizabeth M. Palmer
    • , Essam Heggy
    •  & Wlodek Kofman
  • Article
    | Open Access

    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
  • Article
    | Open Access

    Identifying the original impactor from craters remains challenging. Here, the authors use chromium and oxygen isotopes to indicate that the Zhamanshin astrobleme impactor was a carbonaceous chrondrite by demonstrating that depleted 17O values are due to exchange with atmospheric oxygen.

    • Tomáš Magna
    • , Karel Žák
    •  & Zdeněk Řanda
  • Article
    | Open Access

    Serpentinization of mantle rocks occurs in a variety of tectonic settings, but the controls on the rates of serpentinization are poorly constrained. Here, the authors developed anin situexperimental method to show that the rate of serpentinization is strongly controlled by the salinity of the reacting fluid.

    • Hector M. Lamadrid
    • , J. Donald Rimstidt
    •  & Robert J. Bodnar
  • Article
    | Open Access

    The Eridania basin on Mars was once the site of a vast inland sea. Here, the authors show that the most ancient materials in the Eridania basin were formed in a deep-water hydrothermal setting and may be an analogue for early environmental conditions on Earth.

    • Joseph R. Michalski
    • , Eldar Z. Noe Dobrea
    •  & Javier Cuadros
  • Article
    | Open Access

    Chlorine-containing species deplete stratospheric ozone and while chlorofluorocarbons have been drastically reduced, dichloromethane concentrations have recently increased rapidly. Hossainiet al. show that continued growth at this rate could result in important delays to Antarctic ozone recovery.

    • Ryan Hossaini
    • , Martyn P. Chipperfield
    •  & John A. Pyle
  • Article
    | Open Access

    The presence of α-seifertite and seiferite in shocked meteorites are used to determine shock pressures. Here, using high-pressure experiments, the authors find that the presence of α-cristobalite does not exclude high-pressure transformation and seifertite does not necessarily indicate high pressures.

    • Ana Černok
    • , Katharina Marquardt
    •  & Leonid Dubrovinsky
  • Article
    | Open Access

    Oxygen contained within cosmic spherules is sourced from the atmosphere, making micrometeorites a possible archive for past atmospheric conditions. Here, Packet al. compare the isotopic composition of oxygen in cosmic spherules from Antarctica with that of the troposphere, and validate the value of this archive.

    • Andreas Pack
    • , Andres Höweling
    •  & Luigi Folco
  • Article
    | Open Access

    Rapid and spatially localized geomagnetic field variations around 1000 BC are hard to reconcile with expected field behaviour arising from the core dynamo. Here, the authors show that the intensity spike is consistent with an intense flux patch on the core-mantle boundary (8–22°) located under Saudi Arabia.

    • Christopher Davies
    •  & Catherine Constable
  • Article
    | Open Access

    Constraining the timing of crustal processes and impact events remains challenging. Here, the authors show that atom probe tomography can produce highly accurate U-Pb isotopic age constraints in baddeleyite crystals, which is a common phase in terrestrial, Martian, Lunar and asteroidal materials.

    • L. F. White
    • , J. R. Darling
    •  & I. Martin
  • Article
    | Open Access

    Summer rainfall in the agriculturally-reliant Sahel is extremely variable, with the region particularly vulnerable to major droughts. Here, the authors investigate the mechanisms that drive Sahel summer rainfall change on inter-annual and multi-year timescales and show that Sahel rainfall can be skilfully predicted.

    • K. L. Sheen
    • , D. M. Smith
    •  & M. Vellinga
  • Article
    | Open Access

    The influence of tectonics, continental weathering, and seafloor weathering in the geological carbon cycle remain unclear. Here, the authors develop a new carbon cycle model and, through comparison with proxy data, critically evaluate the influence of these components on carbon fluxes since 100 Ma.

    • Joshua Krissansen-Totton
    •  & David C. Catling
  • Article
    | Open Access

    The composition of the early Earth’s atmosphere remains unclear. Here, the authors using fluid inclusions trapped within quartz crystals show that at 3.3 Ga the atmosphere had a lower129Xe excess than today, and suggest that comets may have brought xenon to the Earth’s atmosphere during terrestrial accretion.

    • Guillaume Avice
    • , Bernard Marty
    •  & Ray Burgess
  • Article
    | Open Access

    Abundant molecular oxygen was discovered recently in the coma of comet 67P, thought to be of primordial origin. Here, the authors propose a dynamic reaction mechanism for cometary comae, which produces O2directly in single collisions of energetic water ions with oxidized cometary surface analogues.

    • Yunxi Yao
    •  & Konstantinos P. Giapis
  • Article
    | Open Access

    The age of weathering inferred from bedrock saprolite local to Scandinavia remains loosely constrained. Here, via K-Ar dating of authigenic, syn-weathering illite from saprolitic remnants, the authors constrain weathering to the Late Triassic.

    • Ola Fredin
    • , Giulio Viola
    •  & Jochen Knies
  • Article
    | Open Access

    Large variations in insolation experienced by circumbinary planets raise the question of the habitability of such planets. Here, the authors show that while the changing insolation does not radically affect habitability, it does impact on the planet’s climate and on the interpretation of future observations.

    • Max Popp
    •  & Siegfried Eggl
  • Article
    | Open Access

    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
  • Article
    | Open Access

    The degree to which debris-covered glaciers record past environmental conditions is debated. Here, the authors show that obliquity-paced variations in solar radiation over the past 220 ka are expressed in Mullins glacier as repetitive changes in englacial debris and corresponding surface topography.

    • Sean L. Mackay
    •  & David R. Marchant
  • Article
    | Open Access

    Raked linear dunes are a rare dune type, but the mechanisms for growth have not been constrained. Here, the authors show that a tridirectional wind regime is required to enable this extremely rare dune type to develop, where the raked pattern may develop preferentially on the leeward side.

    • Ping Lü
    • , Clément Narteau
    •  & Sylvain Courrech du Pont
  • Article
    | Open Access

    The high amount of L-type chondrites discovered in Ordovician sediments has previously been linked with the Great Ordovician Biodiversification Event. But here, Lindskoget al. present new zircon ages that date the chondrite dispersion to 468.0±0.3 Ma, showing that the two events may be unrelated.

    • A. Lindskog
    • , M. M. Costa
    •  & M. E. Eriksson
  • Article
    | Open Access

    The long-term Lorenz energy cycle of Earth’s global remains poorly explored. Here, the authors use three independent meteorological data sets from the modern satellite era (1979–2013) to examine the temporal characteristics of such a cycle.

    • Yefeng Pan
    • , Liming Li
    •  & Andrew P. Ingersoll
  • Article
    | Open Access

    Erosion rates and ice cover extent of present day fjords and summit plateau landscapes beyond the last deglaciation are virtually unknown. Here, the authors constrain the long-term denudation rates and glaciation history in west Greenland based on cosmogenic nuclides.

    • Astrid Strunk
    • , Mads Faurschou Knudsen
    •  & Nicolaj K. Larsen
  • Article
    | Open Access

    Surface meltwater draining to the bed of the Greenland Ice Sheet each summer causes ice flow changes inconsistent with the prevailing theory of channelizing subglacial drainage. Here, the authors show this is caused by limited, gradual leakage of water from previously ignored weakly connected regions of the bed.

    • Matthew J. Hoffman
    • , Lauren C. Andrews
    •  & Blaine Morriss
  • Article
    | Open Access

    Earthquakes have been theorised to produce gravity signals that may arrive before seismic waves, but until now they had not been detected. Montagneret al. have detected prompt gravity signals from the 2011 Tohoku-Oki earthquake thus allowing an early warning of earthquakes before seismic wave arrival.

    • Jean-Paul Montagner
    • , Kévin Juhel
    •  & Philippe Lognonné
  • Article
    | Open Access

    One hypothesis for solar system formation is gas compression by a nearby supernova, whose traces should be found in isotopic anomalies. Here the authors show that this mechanism is viable only if the triggering event was a low-mass supernova, looking at short-lived 10Be and lack of anomalies in stable isotopes.

    • Projjwal Banerjee
    • , Yong-Zhong Qian
    •  & W C Haxton
  • Article
    | Open Access

    The origin, variability, and structure of Saturn’s intense and broad eastward equatorial jet at upper cloud level are complex and unexplained. Here, based on observations of a large, bright equatorial disturbance in 2015, the authors characterise the vertical structure of the jet and its long-term variability.

    • A. Sánchez-Lavega
    • , E. García-Melendo
    •  & T. Barry
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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