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| Open AccessBiogenic carbonate mercury and marine temperature records reveal global influence of Late Cretaceous Deccan Traps
The relative role of the Deccan Traps volcanic activity versus the role of the Chicxulub impact event in terms of potential contributions to the Cretaceous-Paleogene (K-Pg) mass extinction has been subject to longstanding debate. Here, the authors observe a global signal of abruptly increased ocean temperatures and elevated [Hg] in the same biogenic carbonate specimens, prior to the impact event but aligning with the onset of Deccan volcanism.
- Kyle W. Meyer
- , Sierra V. Petersen
- & Ian Z. Winkelstern
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Article
| Open AccessKinetics and detectability of the bridgmanite to post-perovskite transformation in the Earth's D″ layer
The D\({}^{{\prime\prime} }\) layer in the Earth’s lower mantle involves a seismic discontinuity which is often assigned to a mineral phase transition to post-perovskite, however, as this phase transition occurs over broad region the assignment of seismic boundaries remains unclear. Here, the authors find that due to the kinetics of the bridgmanite to post-perovskite transformation, thick transition layers can be detected by seismic reflections, unlike previously thought.
- Christopher Langrand
- , Denis Andrault
- & Sébastien Merkel
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Article
| Open AccessNo evidence for high-pressure melting of Earth’s crust in the Archean
Some of Earth’s earliest continental crust has been previously inferred to have formed from partial melting of hydrated mafic crust at pressures above 1.5 GPa (more than 50 km deep), pressures typically not reached in post-Archean continental crust. Here, the authors show that such high pressure signatures can result from melting of mantle sources rather than melting of crust, and they suggest there is a lack of evidence that Earth’s earliest crust melted at depths significantly below 40 km.
- Robert H. Smithies
- , Yongjun Lu
- & Marc Poujol
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| Open AccessSaline aqueous fluid circulation in mantle wedge inferred from olivine wetting properties
The authors here perform experiments to investigate the dihedral angle of olivine-H2O and olivine-H2O-NaCl systems. The observed effect of NaCl to decrease dihedral angles allows fluids to percolate through forearc mantle wedge and to accumulate in the overlying crust, accounting for the high electrical conductivity anomalies in forearc regions.
- Yongsheng Huang
- , Takayuki Nakatani
- & Catherine McCammon
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Article
| Open AccessLarge Igneous Province thermogenic greenhouse gas flux could have initiated Paleocene-Eocene Thermal Maximum climate change
The Paleocene-Eocene Thermal Maximum constitutes one of the largest climate perturbations in Earth’s history, but its exact causes are not well known. New estimates of greenhouse gas fluxes from the North Atlantic Igneous Province at high temporal resolution show that they could have initiated this event.
- Stephen M. Jones
- , Murray Hoggett
- & Tom Dunkley Jones
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Article
| Open AccessSuperplume mantle tracked isotopically the length of Africa from the Indian Ocean to the Red Sea
Low seismic velocity anomalies reveal a complex scenario of plume upwellings from a deep thermo-chemical anomaly (superplume) in the mantle below the East African Rift, however, geophysical observations alone are insufficient to identify the extent of plume influence on the magmatism along the rift. Here, the authors use Sr-Nd-Pb isotope data to show that superplume mantle underlies the entire rift system, from the Red Sea to the Indian Ocean south of Mozambique.
- John M. O’Connor
- , Wilfried Jokat
- & Anthony A. P. Koppers
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| Open AccessSouthern Africa crustal anisotropy reveals coupled crust-mantle evolution for over 2 billion years
The long-term stability of Precambrian continental lithosphere depends on the rheology of the lithospheric mantle as well as the coupling between crust and mantle lithosphere. Here, the authors study crustal seismic anisotropy to reveal that the crust and mantle lithosphere of southern Africa have been coupled since cratonisation, over 2 billion years ago.
- H. Thybo
- , M. Youssof
- & I. M. Artemieva
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Article
| Open AccessA general orientation distribution function for clay-rich media
A reference function for describing the orientation of clay platelets in clay-rich materials is still lacking, but is necessary for applications such as prediction of water and solute transfer and designs of innovative materials. Here, the authors determine a reference orientation function of clay platelets, and validate their function for both engineered and natural clay-rich media.
- Thomas Dabat
- , Fabien Hubert
- & Eric Ferrage
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Article
| Open AccessExposed soil and mineral map of the Australian continent revealing the land at its barest
In this study, the authors combine Landsat images spanning 30 years with a new statistical estimator to produce a soil and mineral spectra map of the Australian continent largely unobscured by vegetation or clouds.
- Dale Roberts
- , John Wilford
- & Omar Ghattas
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Article
| Open AccessGlobal geochemical fingerprinting of plume intensity suggests coupling with the supercontinent cycle
The links between plate tectonics and deep mantle structure remain unclear. Here, the authors demonstrate that transition elements (Ni, Cr, and Fe/Mn) in basaltic rocks can be used as a tool to trace plume-related magmatism through Earth history, and their results indicate the presence of a direct relationship between the intensity of plume magmatism and the supercontinent cycle.
- Hamed Gamal EL Dien
- , Luc S. Doucet
- & Ross Mitchell
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Article
| Open AccessEvidence of reactivation of a hydrothermal system from seismic anisotropy changes
In this study, the authors monitor a hydrothermal fluid surge through seismic anisotropy changes at the Hakone volcanic field, Japan. The authors find the anisotropy changes to be set off by the seismic waves of the 2011 Tohoku-Oki earthquake, that reactivated the hydrothermal system.
- Maria Saade
- , Kohtaro Araragi
- & Florent Brenguier
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Article
| Open AccessGeodynamic evolution of southwestern North America since the Late Eocene
The tectonic evolution of southwestern North America remains debated. Here, the authors present a complete time-dependent geodynamic model of the tectonic evolution of southwestern North America, which can explain the extensional collapse of the Basin and Range Province since the Late Eocene.
- Alireza Bahadori
- & William E. Holt
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Article
| Open AccessCr-spinel records metasomatism not petrogenesis of mantle rocks
Chromian-spinel from mafic-ultramafic rocks is used as a reliable geotectonic and mantle melting indicator. Here, the authors argue that this only works partially – it can be used to assess information on mantle metasomatic processes but not petrogenesis.
- Hamed Gamal El Dien
- , Shoji Arai
- & Mohamed Hamdy
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Article
| Open AccessHydrothermal alteration of andesitic lava domes can lead to explosive volcanic behaviour
The permeability of a dome exerts a control on the outgassing efficiency of the underlying magma. The authors investigate the role of hydrothermal alteration on this process in the laboratory and use these data to model whether the overpressures generated are capable of promoting explosive behaviour.
- Michael J. Heap
- , Valentin R. Troll
- & Thomas R. Walter
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Article
| Open AccessNoble gases confirm plume-related mantle degassing beneath Southern Africa
The elevation and high heat flow of Southern South Africa has controversially been attributed to a mantle plume. Here, the authors link degassed CO2 to a non-degassed mantle source rather than the convecting upper mantle, confirming plume-related mantle melting.
- S. M. V. Gilfillan
- , D. Györe
- & F. M. Stuart
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Article
| Open AccessDiamond growth from organic compounds in hydrous fluids deep within the Earth
Diamonds can give us clues to the processes regulating deep carbon transport within the Earth. Here, the author discovers evidence from diamond coatings that organic compounds exist at great depth in Earth’s interior, and furthermore, that organic molecules may provide scaffolds for diamond nucleation and growth.
- Maria Luce Frezzotti
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Article
| Open AccessCritical dependence of morphodynamic models of fluvial and tidal systems on empirical downslope sediment transport
Morphological development of fluvial and tidal systems is increasingly forecasted by models, with most of them predicting unrealistically high channel incision. Here, the authors point out reasons why and suggest improvements.
- A. W. Baar
- , M. Boechat Albernaz
- & M. G. Kleinhans
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| Open AccessCompositional boundary layers trigger liquid unmixing in a basaltic crystal mush
This study seeks to tackle the question of why intermediate magmatic rock compositions are poorly represented on the Earth’s surface. The authors do so by tracking the evolution of the physical behaviour of immiscible Fe-rich liquids within a sample suite from the lava lake on the Kilauea Iki volcano, Hawaii.
- Victoria C. Honour
- , Marian B. Holness
- & Marlon M. Jean
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| Open AccessMolybdenum systematics of subducted crust record reactive fluid flow from underlying slab serpentine dehydration
Fluid liberation and migration from subducted oceanic slabs play a critical role in arc magmatism but the volume and origin of the released fluids is unclear and difficult to trace. Here, the authors use Molybdenum isotope ratios to tackle these problems.
- Shuo Chen
- , Remco C. Hin
- & Tim Elliott
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Article
| Open AccessMetamorphic pressure variation in a coherent Alpine nappe challenges lithostatic pressure paradigm
The geodynamic evolution of mountain ranges can be reconstructed using the pressure recorded by minerals in metamorphic rocks, under the key assumption that rock pressure is lithostatic. Here, the authors challenge the lithostatic pressure paradigm by showing that there can be significant outcrop-scale pressure gradients due to compression- and reaction-induced stress.
- Cindy Luisier
- , Lukas Baumgartner
- & Torsten Vennemann
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| Open AccessTiming and origin of natural gas accumulation in the Siljan impact structure, Sweden
Fractured rocks of impact craters have been suggested to be suitable hosts for deep microbial communities on Earth, and potentially other terrestrial planets, yet direct evidence remains elusive. Here, the authors show that the Siljan impact structure is host to long-term deep methane-cycling microbial activity.
- Henrik Drake
- , Nick M. W. Roberts
- & Mats E. Åström
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Matters Arising
| Open AccessWiggle-match radiocarbon dating of the Taupo eruption
- Alan G. Hogg
- , Colin J. N. Wilson
- & Fiona Petchey
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Article
| Open AccessOrganic sulfur was integral to the Archean sulfur cycle
Marine chemistry during the Early Earth (over 2.7 billion years ago) is commonly inferred to have been inorganically sulfate-reducing. Here, the authors argue that organic sulfur cycling may have played a previously unrecognized, yet important, role in the formation of ancient Archean marine sulfides.
- Mojtaba Fakhraee
- & Sergei Katsev
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Article
| Open AccessPacific subduction control on Asian continental deformation including Tibetan extension and eastward extrusion tectonics
The India-Asia collision has formed the highest mountains on Earth and is associated with extensive intraplate deformation. Here, the authors present geodynamic experiments of continental deformation across Central, East, and Southeast Asia which suggest that the Pacfic and Sunda subduction zones played an active role during intraplate deformation.
- W. P. Schellart
- , Z. Chen
- & F. M. Rosas
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Article
| Open AccessComplex hazard cascade culminating in the Anak Krakatau sector collapse
On 22 December 2018, the western flank of Anak Krakatau collapsed into the sea of the Sunda Strait triggering a tsunami which killed approximately 430 people and displaced 33,000. Here, the authors show that Anak Krakatau exhibited an elevated state of activity several months prior to the collapse, including precursory thermal anomalies, an increase in the island’s surface area, and a gradual seaward motion of the southwestern flank.
- Thomas R. Walter
- , Mahmud Haghshenas Haghighi
- & Peter Gaebler
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Article
| Open AccessObtaining free USArray data by multi-dimensional seismic reconstruction
The USArray of EarthScope is a seismic broadband network acquiring global seismic data. Here, the authors apply an iterative rank-reduction method to obtain free earthquake data at locations where no seismic stations are available as well as enhancing existing data recorded by the USArray.
- Yangkang Chen
- , Min Bai
- & Yunfeng Chen
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Article
| Open AccessNew flow relaxation mechanism explains scour fields at the end of submarine channels
The nature of erosion featured at the outlet of submarine channels is still a topic of debate. Here the authors present, based on scaled experiments, a novel flow mechanism for turbidity currents at the end of submarine channels and for the first time describe their erosional character.
- F. Pohl
- , J. T. Eggenhuisen
- & M. J. B. Cartigny
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Article
| Open AccessThe risks of long-term re-injection in supercritical geothermal systems
Can we pump water into deep active volcanic areas? Here, the authors model the effect of water circulation into supercritical geothermal systems and show that the effect of rock cooling dominates the seismicity increase over the pore pressure changes.
- Francesco Parisio
- , Victor Vilarrasa
- & Thomas Nagel
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Article
| Open AccessLow CO2 levels of the entire Pleistocene epoch
Climate dynamics in Earth’s distant history can provide important forecasting for future changes, but uncertainties in proxy-derived carbon dioxide results are common. Here Da and colleagues present a refined paleosol proxy for carbon dioxide reconstruction, and report persistently low levels ( < 300 ppm) throughout the Pleistocene interglacials.
- Jiawei Da
- , Yi Ge Zhang
- & Junfeng Ji
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Article
| Open AccessSulphur isotopes of alkaline magmas unlock long-term records of crustal recycling on Earth
Sulphur isotopes track recycling of subducted crustal material, yet few igneous rocks preserve these signals over Earth history. Here, the authors investigate a billion-year-old alkaline province in Greenland and are able to reconstruct a recycled mantle source, thus alkaline rocks can be used to reveal crustal recycling through geological time.
- William Hutchison
- , Rainer J. Babiel
- & Nicola J. Horsburgh
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Article
| Open AccessSynchronous 500-year oscillations of monsoon climate and human activity in Northeast Asia
Long-term climate cycles can potentially influence population dynamics, including those of humans. Here, the authors combine climate and archaeological records from Northeast China over the past 8000 years and demonstrate ~500 year cycles in both the monsoon and human activity.
- Deke Xu
- , Houyuan Lu
- & Naiqin Wu
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Article
| Open AccessForecasting the magnitude of the largest expected earthquake
Forecasting aftershock earthquakes is a critical step in improving seismic hazard mitigation. The authors here combine Bayesian methods with extreme value theory to tackle this problem - and manage to estimate the maximum magnitude of an expected earthquake as well as the arrival times in a pre-defined window.
- Robert Shcherbakov
- , Jiancang Zhuang
- & Yosihiko Ogata
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Article
| Open AccessEarthquake crisis unveils the growth of an incipient continental fault system
The Al-Idrissi Fault System in the Alboran Sea is a major tectonic structure in its initial stage. By using bathymetric and seismic reflection data, the authors unravel a 3D geometry for the AIFS, which corresponds to a crustal-scale boundary and provides a unique model of the inception and growth of a young plate boundary fault system.
- Eulàlia Gràcia
- , Ingo Grevemeyer
- & César R. Ranero
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Article
| Open AccessFluid dynamic induced break-up during volcanic eruptions
Determining if a volcanic eruption will behave effusively or explosively is crucial for predicting the potential hazard type and for planning effective mitigation. Here, the authors present a universal, fluid dynamic induced, break-up criterion for low viscosity melts.
- T. J. Jones
- , C. D. Reynolds
- & S. C. Boothroyd
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Article
| Open AccessShale gas reserve evaluation by laboratory pyrolysis and gas holding capacity consistent with field data
Quantification of shale gas reserves is critical to shape the energy policies of countries. Here, the authors present a new procedure to estimate gas in place and show that important UK gas reserves are actually much lower than previously thought.
- Patrick Whitelaw
- , Clement N. Uguna
- & Andrew D. Carr
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Comment
| Open AccessFingerprinting metal transfer from mantle
The ore-forming magmas in post-subduction copper deposits are thought to be derived from the lower crust. The Au-Te fingerprints of post-subduction magmas reveal an important role for the metasomatized sub-crustal lithospheric mantle in the formation of porphyry and epithermal copper deposits.
- Zengqian Hou
- & Rui Wang
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Article
| Open AccessA metasomatized lithospheric mantle control on the metallogenic signature of post-subduction magmatism
Hydrous and alkali rich magmas rise through the lithosphere and may host gold-rich ore deposits – a poorly understood process. Here, the authors present new chalcophile element data across a metallogenic section of the lithosphere and suggest a continuous or staged ascent of magmatic-hydrothermal settings from mantle to upper crust.
- David A. Holwell
- , Marco Fiorentini
- & Marek Locmelis
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Article
| Open AccessContinuous plate subduction marked by the rise of alkali magmatism 2.1 billion years ago
The point in time in which the ancient stagnant-lid tectonic regime with episodic plate subduction changed to continuous plate subduction is still topic of scientific debate. Here, the authors present vast geochemical dataset covering the last 3.5 billion years of Earth’s history and date the onset of continuous subduction to about 2.1 billion years ago.
- He Liu
- , Wei-dong Sun
- & Ming Tang
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Article
| Open AccessHotspot motion caused the Hawaiian-Emperor Bend and LLSVPs are not fixed
Controversy surrounds the fixity of both hotspots and large low shear velocity provinces (LLSVPs). Here, the authors present new paleomagnetic data to show that the great bend in the Hawaiian-Emperor seamount chain can be attributed to mantle plume motion and that LLSVPs are mobile.
- Richard K. Bono
- , John A. Tarduno
- & Hans-Peter Bunge
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Article
| Open AccessNorthward drift of the Azores plume in the Earth’s mantle
Tectonic plate motions are often reconstructed based on the assumption that mantle plumes are fixed within the mantle. Here, the authors provide geochemical and geodynamic evidence to suggest that the asymmetry of the Azores thermal anomaly can be explained by northward motion of the Azores plume.
- Maëlis Arnould
- , Jérôme Ganne
- & Xiaojun Feng
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Article
| Open AccessAncient recycled lower crust in the mantle source of recent Italian magmatism
Recycling of Earth’s crust through subduction and delamination contributes to mantle heterogeneity. Here, the authors measure coupled Sr-Nd-Pb isotope compositions of melt inclusions in Italian potassium-rich lavas, they suggest their results indicate a potential ancient lower crustal component in the mantle source.
- Janne M. Koornneef
- , Igor Nikogosian
- & Gareth R. Davies
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Article
| Open AccessHigh density oilfield wastewater disposal causes deeper, stronger, and more persistent earthquakes
Oilfield wastewater is commonly discarded by pumping it into deep geologic formations, but this process is now known to cause earthquakes. Here, he authors show that high-density oilfield wastewater may sink deeper in the Earth’s crust than previously considered possible, thus increasing fluid pressure and inducing earthquakes for years after injection rates decline.
- Ryan M. Pollyea
- , Martin C. Chapman
- & Hao Wu
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Article
| Open AccessOrigin of ocean island basalts in the West African passive margin without mantle plume involvement
The genesis of hotspot magmatism remains controversial especially at continental margins such as offshore West Africa. Here, by analysing trace element and Pb isotopes of intraplate basalts, the authors conclude that their generation was caused by the melting of two fusible regions of subcontinental lithospheric mantle.
- Iyasu Getachew Belay
- , Ryoji Tanaka
- & Eizo Nakamura
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Article
| Open AccessInterseismic strain build-up on the submarine North Anatolian Fault offshore Istanbul
The state of the Main Marmara Fault (fault segment of the North Anatolian Fault) is widely discussed, towards whether it is creeping or locked. The authors here present seafloor geodetic measurements which indicate a complete locking of the fault in the central part of the Sea of Marmara. This provides significant information for the assessment of both seismic and potential tsunami hazard to Istanbul.
- Dietrich Lange
- , Heidrun Kopp
- & Louis Géli
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Article
| Open AccessForecasting of the first hour aftershocks by means of the perceived magnitude
The timing and locations of aftershocks following the initial impact of an earthquake are key to mitigate potential further hazards. Here the authors use the seismic ground velocity as input parameter to provide accurate probabilities of post seismic occurrence within 30 min of the main shock.
- E. Lippiello
- , G. Petrillo
- & V. Karakostas
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Article
| Open AccessRate-and-state friction explains glacier surge propagation
Predicting the friction at the ice/bedrock interface prevents a full understanding of glacier dynamics. Here, the authors present a framework for the transient evolution of basal shear stress and incorporate it in glacier simulations. This tool is capable of explaining surge onset and propagation.
- Kjetil Thøgersen
- , Adrien Gilbert
- & Anders Malthe-Sørenssen
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Article
| Open AccessCoulomb pre-stress and fault bends are ignored yet vital factors for earthquake triggering and hazard
Scattered earthquake locations in the same region cannot be explained solely by coseismic Coulomb stress on planar faults. Instead, the authors suggest Coulomb pre-stress to influence earthquake locations. Pre-stress was modelled on strike-variable faults and consists of coseismic and interseismic Coulomb stress.
- Z. K. Mildon
- , G. P. Roberts
- & S. Toda
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Article
| Open AccessMicrobially induced potassium enrichment in Paleoproterozoic shales and implications for reverse weathering on early Earth
The transition from smectite to illite requires potassium incorporation, yet the role of microbes in facilitating K+ uptake remains debated, especially during the early Earth. Here, the authors suggest that the Paleoproterozoic microbial mats extracted potassium from sea water and induced localized illitization during early low-temperature diagenesis.
- Jérémie Aubineau
- , Abderrazak El Albani
- & Kurt O. Konhauser
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Article
| Open AccessThe mechanism of tidal triggering of earthquakes at mid-ocean ridges
Tidal triggering of earthquakes at Axial Volcano on the Juan de Fuca ridge is shown to be driven by tidally induced magma chamber inflation. Fitting the data to theory requires that the frictional parameter A be much smaller than laboratory measurements indicate.
- Christopher H. Scholz
- , Yen Joe Tan
- & Fabien Albino