Article
|
Open Access
Featured
-
-
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
-
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
-
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
-
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
-
Article
| Open AccessThe formation and evolution of Titan’s winter polar vortex
The polar hot-spot appeared in Titan after equinox in 2010 suddenly cooled in early 2012, which wasn’t predicted by models. Here the authors use observations to show that the increase in trace gases during the hot-spot resulted in radiative cooling feedback.
- Nicholas A. Teanby
- , Bruno Bézard
- & F. Michael Flasar
-
Article
| Open AccessRedox-independent chromium isotope fractionation induced by ligand-promoted dissolution
The chromium (Cr) isotope system has emerged as a potential proxy for tracing Earth’s atmospheric evolution based on a redox-dependent framework. Here the authors show that ligand-complexation, a redox-independent process, must be considered when using Cr isotope signatures to diagnose atmospheric oxygen levels.
- Emily M. Saad
- , Xiangli Wang
- & Yuanzhi Tang
-
Article
| Open AccessTime-resolved diffraction of shock-released SiO2 and diaplectic glass formation
Our understanding of shock metamorphism and thus the collision of planetary bodies is limited by a dependence on ex situ analyses. Here, the authors perform in situ analysis on shocked-produced densified glass and show that estimates of impactor size based on traditional techniques are likely inflated.
- A. E. Gleason
- , C. A. Bolme
- & W. L. Mao
-
Article
| Open AccessRiver-bed armouring as a granular segregation phenomenon
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 AccessMarine oxygen production and open water supported an active nitrogen cycle during the Marinoan Snowball Earth
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 AccessClay mineral formation under oxidized conditions and implications for paleoenvironments and organic preservation on Mars
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 AccessWater induced sediment levitation enhances downslope transport on Mars
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 AccessEnhanced ice sheet melting driven by volcanic eruptions during the last deglaciation
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 AccessElevated CO2 degassing rates prevented the return of Snowball Earth during the Phanerozoic
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 AccessCoralgal reef morphology records punctuated sea-level rise during the last deglaciation
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 AccessElevated olivine weathering rates and sulfate formation at cryogenic temperatures on Mars
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 AccessHighly compressed water structure observed in a perchlorate aqueous solution
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 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
-
Article
| Open AccessTaking the pulse of Mars via dating of a plume-fed volcano
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 AccessOrbital bistatic radar observations of asteroid Vesta by the Dawn mission
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 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
-
Article
| Open AccessZhamanshin astrobleme provides evidence for carbonaceous chondrite and post-impact exchange between ejecta and Earth’s atmosphere
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 AccessEffect of water activity on rates of serpentinization of olivine
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 AccessAncient hydrothermal seafloor deposits in Eridania basin on Mars
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 AccessThe increasing threat to stratospheric ozone from dichloromethane
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 AccessCompressional pathways of α-cristobalite, structure of cristobalite X-I, and towards the understanding of seifertite formation
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 AccessNew Martian valley network volume estimate consistent with ancient ocean and warm and wet climate
To understand the early Martian climate, the volume of the global Martian valley network is required. Here, the authors use a black top hat transformation method and find that the minimum global valley network volume is 1.74 × 1,014 m3 with a minimum cumulative volume of water required of 6.86 × 1,017 m3.
- Wei Luo
- , Xuezhi Cang
- & Alan D. Howard
-
Article
| Open AccessTracing the oxygen isotope composition of the upper Earth’s atmosphere using cosmic spherules
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 AccessGeomagnetic spikes on the core-mantle boundary
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 AccessAtomic-scale age resolution of planetary events
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 AccessSkilful prediction of Sahel summer rainfall on inter-annual and multi-year timescales
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 AccessConstraining climate sensitivity and continental versus seafloor weathering using an inverse geological carbon cycle model
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 AccessThe origin and degassing history of the Earth's atmosphere revealed by Archean xenon
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 AccessDynamic molecular oxygen production in cometary comae
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 AccessThe inheritance of a Mesozoic landscape in western Scandinavia
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 AccessMeasurement of the cosmic optical background using the long range reconnaissance imager on New Horizons
The cosmic optical background is an important cosmological observable. Here the authors show that a direct observation of the background brightness from the outer solar system can be obtained by the LORRI instrument aboard the New Horizons mission, on the basis of data acquired between Jupiter and Uranus.
- Michael Zemcov
- , Poppy Immel
- & Andrew R. Poppe
-
Article
| Open AccessClimate variations on Earth-like circumbinary planets
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 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
-
Article
| 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
-
Article
| Open AccessObliquity-paced climate change recorded in Antarctic debris-covered glaciers
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 AccessUnravelling raked linear dunes to explain the coexistence of bedforms in complex dunefields
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 AccessRefined Ordovician timescale reveals no link between asteroid breakup and biodiversification
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 AccessEarth’s changing global atmospheric energy cycle in response to climate change
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 AccessOne million years of glaciation and denudation history in west Greenland
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 AccessGreenland subglacial drainage evolution regulated by weakly connected regions of the bed
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 AccessPrompt gravity signal induced by the 2011 Tohoku-Oki earthquake
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 AccessEvidence from stable isotopes and 10Be for solar system formation triggered by a low-mass supernova
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 AccessSilica deposits on Mars with features resembling hot spring biosignatures at El Tatio in Chile
Hydrothermal deposits on Mars may provide the best opportunity to find Martian biosignatures. Ruff and Farmer report that silica structures created by biotic and abiotic process in hot springs at El Tatio, Chile resemble those found in Gusev crater, thus making it an ideal location for future missions.
- Steven W. Ruff
- & Jack D. Farmer
-
Article
| Open AccessAmazonian chemical weathering rate derived from stony meteorite finds at Meridiani Planum on Mars
Little is known about the impacts of Mars’ contemporary dryness on weathering processes. Here, using iron oxidation estimates from the Mars Rover Opportunity, the authors quantify chemical weathering rates for Mars, finding appreciably slower rates compared with the lowest values on Earth.
- Christian Schröder
- , Phil A. Bland
- & John A. Grant
-
Article
| Open AccessAn enduring rapidly moving storm as a guide to Saturn’s Equatorial jet’s complex structure
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
Browse broader subjects
Browse narrower subjects
- Asteroids, comets and Kuiper belt
- Astrobiology
- Atmospheric chemistry
- Atmospheric dynamics
- Core processes
- Cryospheric science
- Early solar system
- Exoplanets
- Geochemistry
- Geodynamics
- Geomorphology
- Giant planets
- Hydrology
- Inner planets
- Meteoritics
- Mineralogy
- Petrology
- Rings and moons
- Seismology
- Structural geology
- Tectonics
- Volcanology