Geochemistry

  • Article
    | Open Access

    Harmful algal and bacterial blooms are increasingly frequent in lakes and rivers. From the Sydney Basin, Australia, this study uses fossil, sedimentary and geochemical data to reveal bloom events following forest ecosystem collapse during the end-Permian event and that blooms have consistently followed warming-related extinction events, inhibiting the recovery of freshwater ecosystems for millennia.

    • Chris Mays
    • , Stephen McLoughlin
    •  & Vivi Vajda
  • Article
    | Open Access

    Chemically variable primitive basalts undergo mixing during ascent from the mantle. Here the authors show observations from magma–magma reaction experiments which demonstrate how isothermal mixing between chemically variable basalts creates and modifies crystal cargoes erupted in oceanic settings.

    • David A. Neave
    • , Philipp Beckmann
    •  & François Holtz
  • Article
    | Open Access

    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
  • Article
    | Open Access

    The Paleocene–Eocene boundary coincided with runaway global warming possibly analogous to future climate change, but the sources of greenhouse gasses have remained unresolved. Here, the authors reveal volcanism triggered initial warming, and subsequent carbon was released after crossing a tipping point.

    • Sev Kender
    • , Kara Bogus
    •  & Melanie J. Leng
  • Article
    | Open Access

    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
  • Article
    | Open Access

    We discover a pervasive subduction influence in the Arctic, Atlantic and Indian mantle, which is nearly absent in the Pacific mantle. Such a hemispheric-scale upper mantle heterogeneity reflects the control of a “subduction shield” that has surrounded the Pacific Ocean for 180 Myr.

    • A. Y. Yang
    • , C. H. Langmuir
    •  & Z. Chen
  • Article
    | Open Access

    How early photosynthesizers managed oxidative stress remains relatively unresolved. Analyses of enzymes dealing with reactive oxygen species traces the evolutionary history of superoxide dismutases and finds evidence of CuZnSOD in the ancestor of all cyanobacteria, dating back to the Archaean.

    • Joanne S. Boden
    • , Kurt O. Konhauser
    •  & Patricia Sánchez-Baracaldo
  • Perspective
    | Open Access

    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
  • Article
    | Open Access

    This paper reveals that potassic alteration can be triggered by Na-rich fluids, indicating that pervasive sequential sodic and potassic alterations associated with mineralization in some of the world’s largest ore deposits may not necessarily reflect externally-driven changes in fluid alkali contents.

    • Gan Duan
    • , Rahul Ram
    •  & Joël Brugger
  • Article
    | Open Access

    Plastics are major marine pollutants, and while research suggests that they can release potential harmful additives into seawater, how environmental conditions influence this is unknown. Here the authors determine that byproducts released from microplastics are less under deep-sea conditions versus surface.

    • Vincent Fauvelle
    • , Marc Garel
    •  & Richard Sempéré
  • Article
    | Open Access

    Carbonate mineral aqueous solubility decreases as carbonates become more Mg-rich during subduction. Coupled with regional variations in amounts of carbon and water subducted, this explains discrepancies in estimates of carbon recycling, suggesting that only around a third returns to the surface.

    • Stefan Farsang
    • , Marion Louvel
    •  & Simon A. T. Redfern
  • Article
    | Open Access

    Elevated Zn isotope compositions occur in K-Pg sedimentary layers of three different depositional environments across North America and the Caribbean. The data indicate a volatilization event, and act as a robust mechanistic indicator of the meteorite impact at the end of the Cretaceous.

    • Ryan Mathur
    • , Brandon Mahan
    •  & Francisca E. Oboh-Ikuenobe
  • Article
    | Open Access

    Reactions at the interface between mineral surfaces and flowing liquids are ubiquitous in nature. Here the authors explore, using surface-specific sum frequency generation spectroscopy and numeric calculations, how the liquid flow affects the charging and dissolution rates leading to flow-dependent charge gradients along the surface.

    • Patrick Ober
    • , Willem Q. Boon
    •  & Mischa Bonn
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    Constraining the thermal state of the lithosphere is crucial to understanding geodynamic regime in early Earth. Here the authors reconstruct ~2.9–2.5 Ga thermal structure of continental lithosphere of the North China Craton using TTG and propose a systematic Archean geodynamic evolution process.

    • Guozheng Sun
    • , Shuwen Liu
    •  & Fangyang Hu
  • Article
    | Open Access

    Why Earth’s crust only started becoming widely preserved in the Eoarchaean, 500 Ma after planetary accretion, is poorly understood. Here, the authors document a shift to juvenile magmatic sources in the early Eoarchaean, linking crustal preservation to the formation of stabilising melt-depleted mantle.

    • Jacob A. Mulder
    • , Oliver Nebel
    •  & Timothy J. Ivanic
  • Article
    | Open Access

    A case study of migmatites indicates that the juvenile arc crust underwent a rapid self-recycling process from arc magmatism to erosion and weathering at the surface, then to burial and remelting. Intra-arc thrust fault systems might efficiently promote endogenous recycling.

    • Jun-Yong Li
    • , Ming Tang
    •  & Lin-Sen Li
  • Article
    | Open Access

    Earth-system sensitivity (ESS) describes the long-term temperature response for a given change in atmospheric CO2 and, as such, is a crucial parameter to assess future climate change. Here, the authors use a Bayesian model with data from the last 420 Myrs to reduce uncertainties and estimate ESS to be around 3.4 °C.

    • Tony E. Wong
    • , Ying Cui
    •  & Klaus Keller
  • Article
    | Open Access

    Present et al. examine the processes controlling lithification of microbial mats in a Caribbean peritidal carbonate environment. The authors present sedimentological and geochemical evidence of a surprising bias against preserving the most robust, widespread microbial ecosystems in the sedimentary record.

    • Theodore M. Present
    • , Maya L. Gomes
    •  & John P. Grotzinger
  • Article
    | Open Access

    Expanded phosphorus availability possibly triggered a marine bioproduction boom after 2.3 billion years ago, but its delivery mechanisms remain unclear. Here we propose a kaolinite shuttle which efficiently adsorbs phosphorus in continental weathering settings and releases it under marine conditions.

    • Weiduo Hao
    • , Kaarel Mänd
    •  & Kurt O. Konhauser
  • Article
    | Open Access

    Through platinum metal-silicate partitioning coefficient measurements, the authors here show that platinum partitioning into metal is lowered at high pressure–temperature conditions. This finding implies that the Earth’s mantle was likely enriched in platinum immediately following the core-mantle differentiation.

    • Terry-Ann Suer
    • , Julien Siebert
    •  & Guillaume Fiquet
  • Article
    | Open Access

    Based on diamond-anvil cell experiments and cutting-edge secondary ion mass spectrometry analyses, the authors here show that hydrogen may be an important constituent in the Earth’s core and also in the metallic cores of any terrestrial planet or moon having a mass in excess of 10% of the Earth.

    • Shoh Tagawa
    • , Naoya Sakamoto
    •  & Hisayoshi Yurimoto
  • Article
    | Open Access

    The authors here propose a chemical reaction that forms ammoniated phyllosilicates on Ceres. This process could trigger at a very low temperature, suggesting Ceres evolution in a region different from its current location.

    • Santosh K. Singh
    • , Alexandre Bergantini
    •  & Ralf I. Kaiser
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    Tectonomagmatic conditions in the Precambrian were hypothesized to be unfavorable for porphyry Cu deposit formation. Here, the authors show that metallogenic processes typify Phanerozoic porphyry Cu deposits operated by ~1.88 Ga, reflecting modification of mantle lithosphere by oxidized slab-derived fluids at that time.

    • Xuyang Meng
    • , Jackie M. Kleinsasser
    •  & Richard A. Stern
  • Article
    | Open Access

    Here, the authors compile a global geochemical database of Neogene-Quaternary intraplate volcanism. By comparing the distribution and composition of these rocks with tomographic models they show that intraplate volcanism can be used to constrain upper-mantle structure at the time of eruption.

    • P. W. Ball
    • , N. J. White
    •  & S. N. Stephenson
  • Article
    | Open Access

    The end-Permian mass extinction was the most severe extinction event in the past 540 million years, and the Siberian Traps large igneous province is widely hypothesized to have been the primary trigger for the environmental catastrophe. In this study, Ni isotopes provide the link between Siberian Traps magmatism and early environmental degradation, ultimately leading to the end-Permian extinction.

    • Menghan Li
    • , Stephen E. Grasby
    •  & Yanan Shen
  • Article
    | Open Access

    Radioactive 137Cs is a fission product remaining in the environment from mid-20th century nuclear testing. Here the authors show that vegetation thousands of kilometers from testing sites continues to cycle 137Cs, and consequently, bees magnify this contaminant in honey in regions with low soil potassium.

    • J. M. Kaste
    • , P. Volante
    •  & A. J. Elmore
  • Article
    | Open Access

    Here, the authors show that Earth and Moon are characterized by different vanadium isotope compositions, which is most likely resulting from vanadium isotope fractionation of the bulk silicate proto-Earth during the main stage of terrestrial core formation—followed by a canonical giant impact scenario, where 80% of the Moon originates from an impactor of chondritic composition.

    • Sune G. Nielsen
    • , David V. Bekaert
    •  & Maureen Auro
  • Article
    | Open Access

    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
  • Article
    | Open Access

    Based on the analysis of chemical maps of Thorium and Potassium derived in the Eridania region on Mars, the authors show how radiogenic heat driven hydrothermal systems may have persisted on Mars.

    • Lujendra Ojha
    • , Suniti Karunatillake
    •  & Jacob Buffo
  • Article
    | Open Access

    The impacts of a melting Arctic on the biogeochemistry of marine ecosystems are unknown. Here, the authors investigate glacial input of iron to Svalbard fjords finding that reworking of glacial iron in fjord sediment is important to make iron bioavailable, but could be susceptible to glacial retreat.

    • Katja Laufer-Meiser
    • , Alexander B. Michaud
    •  & Bo Barker Jørgensen
  • Article
    | Open Access

    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
  • Article
    | Open Access

    It is widely hypothesised that primeval life utilized small organic molecules as sources of carbon and energy, however, the presence of such primordial ingredients in early Earth habitats has not yet been demonstrated. Here the authors report the existence of indigenous organic molecules and gases in primary fluid inclusions in c. 3.5- billion-year-old rocks from Western Australia.

    • Helge Mißbach
    • , Jan-Peter Duda
    •  & Volker Thiel
  • Article
    | Open Access

    Soil organic matter (SOM) is a huge sink of carbon, but the varied flux dynamics are challenging to predict. Here, the authors present a new model with the complexities of SOM cycling, including parameters for substrate accessibility, microbe diversity, and enzymatic substrate depolymerization.

    • Julien Sainte-Marie
    • , Matthieu Barrandon
    •  & Delphine Derrien
  • Article
    | Open Access

    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
  • Article
    | Open Access

    Global oxygen regulation over Earth history has largely depended on variations in organic carbon burial, which includes the suppression of land vegetation due to fires. Here, the authors show that major evolutionary changes in plant ecosystems could have influenced fire regimes and thus affected atmospheric O2.

    • Claire M. Belcher
    • , Benjamin J. W. Mills
    •  & Andrew J. Watson
  • Article
    | Open Access

    The authors report in-situ formation of jarosite witin the Talos Dome ice core (East Antarctica) and show that this ferric-potassium sulfate mineral is present in ice deeper than 1000 meters and progressively increases with depth. This has implications for the presence and formation mechanisms of jarosite observed on Mars.

    • Giovanni Baccolo
    • , Barbara Delmonte
    •  & Massimo Frezzotti
  • Article
    | Open Access

    The nature and evolution of Earth’s crust during the Hadean and Eoarchean is largely unknown due to the lack of preserved material from this period. Here, the authors document a period of crustal rejuvenation between 3.2 and 3.0 Ga, coincident with peak mantle potential temperatures that imply greater degrees of mantle melting and injection of hot mafic-ultramafic magmas into older Hadean-to-Eoarchean felsic crust at this time.

    • C. L. Kirkland
    • , M. I. H. Hartnady
    •  & J. A. Hollis
  • Article
    | Open Access

    Burial of organic material in marine sediments can sequester massive amounts of carbon, but the dynamics of this carbon sink are poorly understood. Here the authors investigate the so-called rusty carbon sink in Arctic shelf sediments, finding that organic carbon-iron associations are stable for 1000 s of years.

    • Johan C. Faust
    • , Allyson Tessin
    •  & Christian März
  • Article
    | Open Access

    This study investigates in the importance of non-fossil fuel NOx emissions in the surface-earth-nitrogen cycle. The study shows how changes of regional human activities directly influence δ15N signatures of deposited NOx to terrestrial environments and that emissions have largely been underestimated.

    • Wei Song
    • , Xue-Yan Liu
    •  & Cong-Qiang Liu
  • Article
    | Open Access

    Groundwater discharge is a mechanism that transports chemicals from inland systems to the ocean, but it has been considered of secondary influence compared to rivers. Here the authors assess the global significance of groundwater discharge, finding that it has a unique and important contribution to ocean chemistry and Earth-system models.

    • Kimberley K. Mayfield
    • , Anton Eisenhauer
    •  & Adina Paytan