-
Novel watermass reconstruction in the Early Mississippian Appalachian Seaway based on integrated proxy records of redox and salinity Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2021-01-18 Geoffrey J. Gilleaudeau; Thomas J. Algeo; Timothy W. Lyons; Steven Bates; Ariel D. Anbar
Redox state and salinity are fundamental properties of watermasses, and in modern environments, detailed analysis of spatial variability in redox and salinity is possible through direct measurement. Watermass reconstruction is difficult in deep-time systems, however, because the sedimentary record of ancient watermasses is often incomplete or difficult to access on spatial scales large enough to permit
-
The many double BSRs across the northern Hikurangi margin and their implications for subduction processes Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2021-01-15 Shuoshuo Han; Nathan L. Bangs; Matthew J. Hornbach; Ingo A. Pecher; Harold J. Tobin; Eli A. Silver
The bottom simulating reflection (BSR) is widely observed along continental margins and is believed to mark the base of gas hydrate stability zone (BGHSZ). In some regions, double or multiple overlapping BSRs are observed, yet their formation mechanisms and geologic implications are not well understood. Here we present 3D seismic images from the 2018 NZ3D experiment that covers a 14×60km2 survey area
-
Selective uptake of rare earth elements in marine systems as an indicator of and control on aerobic bacterial methanotrophy Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2021-01-15 Annaliese C.S. Meyer; Damian Grundle; Jay T. Cullen
Unicellular methanotrophs are a widespread, polyphyletic group of organisms that oxidize methane to assimilate carbon and obtain energy. Methanotrophs are of interest to astrobiologists given their prevalence in terrestrial environmental niches, like geothermal hot springs and hydrothermal vents, that are homologs for proposed extraterrestrial targets. Recent research demonstrates that light rare earth
-
Abraded pyroclastic linear paleodunes in Syria and Daedalia Plana, Mars Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2021-01-13 Kirby D. Runyon; Christina E. Viviano; Mackenzie Day
In the aeolian-dominated conditions of modern Mars, wind-driven sediment deposition and erosion produce a wide range of enigmatic landforms on the planet's surface. In this work, we explore a widespread occurrence of paleodunes on the surface of Mars. These fossilized bedforms preserve morphologies consistent with transverse dunes, implying an approximately unimodal ancient sediment transport azimuth
-
Geomagnetic field intensity changes in the Central Mediterranean between 1500 BCE and 150 CE: Implications for the Levantine Iron Age Anomaly evolution Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2021-01-12 M. Rivero-Montero; M. Gómez-Paccard; D. Kondopoulou; E. Tema; F.J. Pavón-Carrasco; E. Aidona; S.A. Campuzano; A. Molina-Cardín; M.L. Osete; A. Palencia-Ortas; F. Martín-Hernández; F. Rubat-Borel; M. Venturino
-
Dynamic triggering of earthquakes in the North Island of New Zealand following the 2016 Mw 7.8 Kaikōura earthquake Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2021-01-12 Dongdong Yao; Zhigang Peng; Yoshihiro Kaneko; Bill Fry; Xiaofeng Meng
Large earthquakes are capable of triggering microseismicity, deep tremor and slow-slip events from intermediate- to long-distance ranges. Unfortunately, earthquake catalogs are typically incomplete right after large mainshocks. Hence, mapping triggering patterns and understanding the underlying triggering mechanism are challenging. Here we present two different types of seismicity responses to dynamic
-
Stirred not shaken; critical evaluation of a proposed Archean meteorite impact in West Greenland Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2021-01-11 Chris Yakymchuk; Christopher L. Kirkland; Aaron J. Cavosie; Kristoffer Szilas; Julie Hollis; Nicholas J. Gardiner; Pedro Waterton; Agnete Steenfelt; Laure Martin
Large meteorite impacts have a profound effect on the Earth's geosphere, atmosphere, hydrosphere and biosphere. It is widely accepted that the early Earth was subject to intense bombardment from 4.5 to 3.8 Ga, yet evidence for subsequent bolide impacts during the Archean Eon (4.0 to 2.5 Ga) is sparse. However, understanding the timing and magnitude of these early events is important, as they may have
-
Geochemical data indicate highly similar sediment compositions for the Grasberg and Burns formations on Meridiani Planum, Mars Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2021-01-08 Thomas M. McCollom; Brian Hynek
The hematite-bearing, sulfate-rich sandstones of the Burns formation at Meridiani Planum are underlain by a thin stratigraphic unit referred to as the Grasberg formation. The sulfate-bearing Grasberg rocks are fine-grained and lack bedding structures, and were previously interpreted to be a distinct lithologic unit based on morphological and chemical differences from the overlying Burns formation.
-
The directional occurrence of the Levantine geomagnetic field anomaly: New data from Cyprus and abrupt directional changes Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2021-01-08 E. Tema; I. Hedley; F.J. Pavón-Carrasco; E. Ferrara; P. Gaber; D. Pilides; M. Toumazou; Y. Violaris; J. Webb; D. Frankel
We present new insights on the directional occurrence of the Levantine Iron Age Anomaly (LIAA) through the analysis of new and previously published directional archaeomagnetic data from Cyprus and nearby countries. The new directions, obtained from in situ baked clay structures such as small hearths and ovens from five Cypriot archaeological sites, dated from 2000 BCE to 1400 CE, are very well defined
-
Unravelling surface and subsurface carbon sinks within the early Martian crust Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2021-01-07 Lucy E. Kissick; Tamsin A. Mather; Nicholas J. Tosca
Understanding the climate history of Mars, one of our closest planetary neighbours, has important implications for understanding the environmental evolution of Earth and other rocky planets in general. The widespread recognition of an extensive sedimentary record modified, at least in part, by liquid water holds much promise to provide evidence about Mars' past. However, unravelling the pressure and
-
Seismic swarms produced by rapid fluid injection into a low permeability laboratory fault Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2021-01-06 Sara Beth L. Cebry; Gregory C. McLaskey
Fluid injection, from activities such wastewater disposal, hydraulic stimulation, or enhanced geothermal systems, decreases effective normal stress on faults and promotes slip. Earthquake nucleation models suggest the slip at low effective normal stress will be stable and aseismic—contrary to observed increases in seismicity that are often attributed to fluid injection. We conducted laboratory experiments
-
Rheological control on the segmentation of the mid-ocean ridges: Laboratory experiments with extension initially perpendicular to the axis Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-12-30 A.L.R. Sibrant; A. Davaille; E. Mittelstaedt
Mid-ocean ridges (MOR) axes are not straight, but segmented over scales of 10s to 100s of kilometers by several types of offsets including transform faults (TF), overlapping spreading centers (OSC) and non-transform, non-overlapping offsets (NTNOO). Variations in axial morphology and segmentation have been attributed to changes in magma supply, axial thermal structure (which depends on mantle temperature
-
The evolution of ice fabrics: A continuum modelling approach validated against laboratory experiments Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-12-29 Daniel H.M. Richards; Samuel S. Pegler; Sandra Piazolo; Oliver G. Harlen
There remains a significant challenge to model ice crystal fabrics both accurately and efficiently within ice-sheet models. We develop the first fully constrained continuum model, validated against experiments, able to predict the evolution of a crystal fabric for any flow field or temperature. For this, we apply a mesoscopic continuum model describing the evolution of a mass distribution function
-
3He evidence for fluid transfer and continental hydration above a flat slab Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-12-28 Coleman D. Hiett; Dennis L. Newell; Micah J. Jessup
The transfer of large volumes of fluid to the overriding lithosphere during flat-slab subduction should drastically alter the physical and chemical properties of continental margins. However, this process is poorly understood and without active magmatism, direct evidence for fluid transfer has remained elusive in modern systems. New helium isotope ratios (3He/4He) and gas species abundances in thermal
-
Constraints on Archean crust recycling and the origin of mantle redox variability from the δ44/40Ca – δ18O – fO2 signatures of cratonic eclogites Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-12-24 Katie A. Smart; Sebastian Tappe; Alan B. Woodland; David R. Greyling; Chris Harris; Nikolaus Gussone
The nature of the deep calcium geochemical cycle through time is unresolved, in part due to the dearth of information about the calcium isotope composition of Archean recycled oceanic crust. Remnants of such ancient oceanic crust are preserved in the form of cratonic mantle eclogites, brought to surface as xenoliths in kimberlite magma eruptions. The δ44/40Ca of fresh mantle-derived eclogite xenoliths
-
Nitrogen and noble gases reveal a complex history of metasomatism in the Siberian lithospheric mantle Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-12-24 Peter H. Barry; Michael W. Broadley
The Siberian flood basalts (SFB) erupted at the end of the Permian period (∼250 Ma) in response to a deep-rooted mantle plume beneath the Siberian Sub-Continental Lithospheric Mantle (SCLM). Plume-lithosphere interaction can lead to significant changes in the structure and chemistry of the SCLM and trigger the release of metasomatic material that was previously stored within the stable craton. Here
-
The first detection of the Madden-Julian Oscillation signal in daily to hourly resolution proxy records derived from a natural archive of Giant Clam Shell (Tridacna spp.) Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-12-21 Hong Yan; Nanyu Zhao; Pengchao Zhou; Chengcheng Liu; Haobai Fei; Ming Li; Fei Liu; Yuanjian Yang; Wei Yang; John Dodson
The Madden-Julian Oscillation (MJO) is the most prominent mode of intraseasonal variability in the tropics which is responsible for much of the observed intraseasonal climate variance not only there but also in higher latitudes. The short time-span of modern instrumental data limits our understanding of the MJO and obtaining MJO information from natural archives could extend this greatly. Here a Giant
-
Explosive mud volcano eruptions and rafting of mud breccia blocks Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-12-16 Adriano Mazzini; Grigorii Akhmanov; Michael Manga; Alessandra Sciarra; Ayten Huseynova; Arif Huseynov; Ibrahim Guliyev
Azerbaijan hosts the highest density of subaerial mud volcanoes on Earth. The morphologies characterizing these structures vary depending on their geological setting, frequency of eruption, and transport processes during the eruptions. Lokbatan is possibly the most active mud volcano on Earth exhibiting impressive bursting events every ∼5 years. These manifest with impressive gas flares that may reach
-
Young lunar mare basalts in the Chang'e-5 sample return region, northern Oceanus Procellarum Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-12-16 Yuqi Qian; Long Xiao; James W. Head; Carolyn H. van der Bogert; Harald Hiesinger; Lionel Wilson
Chang'e-5, China's first lunar sample return mission, is targeted to land in northern Oceanus Procellarum, within a region selected on the basis of 1) its location away from the Apollo-Luna sampling region, 2) the presence of the Procellarum KREEP Terrane (PKT), 3) the occurrence of one of the youngest lunar mare basalts (Em4), and 4) its association with Rima Sharp. In order to provide context for
-
Quantifying dynamic pressure and temperature conditions on fault asperities during earthquake slip Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-12-11 Kathryn S. Hayward; Charles Le Losq; Stephen F. Cox
New insights into the pressure and temperature conditions on fault surfaces during seismic slip are provided by Raman-active vibrational modes of SiO2 glass. We performed triaxial stick-slip experiments at room temperature and high normal stresses on pre-ground, high-purity silica glass surfaces. During slip, velocities exceed 0.32 m s−1 over durations of less than one millisecond, generating frictional
-
Isotopic signatures as tools to reconstruct the primordial architecture of the Solar System Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-12-10 Jan Render; Gregory A. Brennecka
The significant reorganization of the early Solar System due to giant planet migration has hampered our understanding of where planetary bodies formed. Previously employed proxies for reconstructing the primordial planetary architecture, such as water content or oxidation state, are complicated by post-accretionary processes. Here we investigate basaltic achondrites for their nucleosynthetic isotope
-
Shear-wave velocity structure beneath the Dinarides from the inversion of Rayleigh-wave dispersion Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-12-09 Tena Belinić; Petr Kolínský; Josip Stipčević
The interaction between the Adriatic microplate (Adria) and Eurasia is the main driving factor in the central Mediterranean tectonics. Their interplay has shaped the geodynamics of the whole region and formed several mountain belts including Alps, Dinarides and Apennines. Among these, Dinarides are the least investigated and little is known about the underlying geodynamic processes. There are numerous
-
Geometrically controlled slow slip enhanced by seismic waves: A mechanism for delayed triggering Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-12-04 David Blank; Julia Morgan; Yannick Caniven
Seismic waves generated during earthquakes induce transient stress changes in the crust. These ephemeral perturbations can trigger critically stressed asperities at remote distances, often with significant time delays. The physical mechanism that governs this phenomenon is not completely resolved. Numerical simulations of dynamic perturbations passing along a heterogeneous pre-stressed fault, demonstrate
-
Crustal-scale wedge tectonics at the narrow boundary between the Tibetan Plateau and Ordos block Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-12-04 Xiaobo Tian; Zhiming Bai; Simon L. Klemperer; Xiaofeng Liang; Zhen Liu; Xiao Wang; Xusong Yang; Yunhao Wei; Gaohua Zhu
-
Constraints on the composition and temperature of LLSVPs from seismic properties of lower mantle minerals Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-12-02 Kenny Vilella; Thomas Bodin; Charles-Edouard Boukaré; Frédéric Deschamps; James Badro; Maxim D. Ballmer; Yang Li
Seismic observations have suggested the presence of two Large Low Shear Velocity Provinces (LLSVPs) in the lowermost mantle whose nature and origin are still debated. Several studies have tried to infer their potential composition using seismic observations with the hope to identify their formation mechanism. In particular, compositions enriched in iron (∼12–14 wt%) and bridgmanite (∼90 vol%) have
-
Evidence for post-nebula volatilisation in an exo-planetary body Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-12-02 John H.D. Harrison; Oliver Shorttle; Amy Bonsor
The loss and gain of volatile elements during planet formation is key for setting their subsequent climate, geodynamics, and habitability. Two broad regimes of volatile element transport in and out of planetary building blocks have been identified: that occurring when the nebula is still present, and that occurring after it has dissipated. Evidence for volatile element loss in planetary bodies after
-
Sub-axial deformation in oceanic lower crust: Insights from seismic reflection profiles in the Enderby Basin and comparison with the Oman ophiolite Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-12-03 Daniel Sauter; Philippe Werner; Georges Ceuleneer; Gianreto Manatschal; Mathieu Rospabé; Julie Tugend; Morgane Gillard; Julia Autin; Marc Ulrich
We analyzed high-quality seismic reflection profiles across the ocean-continent transition in the Enderby Basin between the Kerguelen Plateau and the Antarctic margin. There, we observe numerous high-amplitude dipping reflections in the lower oceanic crust which was accreted at a magmatic spreading center as testified by the almost uniform 6.4-7 km thick crust and its unfaulted, flat top basement.
-
Velocity-weakening friction induced by laboratory-controlled lithification Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-12-01 Matt J. Ikari; Andre Hüpers
Regarding the occurrence of seismicity on major plate-boundary fault zones, one leading hypothesis is that the processes of lithification is responsible transforming loose, unconsolidated sediment that does not host earthquake nucleation into the frictionally unstable rocks that inhabit the seismogenic zone. Previous laboratory studies comparing the frictional properties of intact rocks and powdered
-
Deposition and erosion of a Light-Toned Yardang-forming unit of Mt Sharp, Gale crater, Mars Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-12-01 G. Dromart; L. Le Deit; W. Rapin; O. Gasnault; S. Le Mouélic; C. Quantin-Nataf; N. Mangold; D. Rubin; J. Lasue; S. Maurice; H.E. Newsom; P. Pinet; L. Scuderi; R.C. Wiens
Gale crater is a large impact crater with a ca 5 km thick sequence of stratified rocks in it, expressed today as a central eroded mound (i.e., Aeolis Mons informally named Mt. Sharp). A goal of the current Mars Science Laboratory mission in Gale crater is to investigate the processes that deposited, lithified, and eroded this fill. The Light-Toned Yardang Unit (LTYu) unit, the subject of the present
-
Mid-infrared spectroscopy of crystalline plagioclase feldspar samples with various Al,Si order and implications for remote sensing of Mercury and other terrestrial Solar System objects Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-30 Maximilian P. Reitze; Iris Weber; Andreas Morlok; Harald Hiesinger; Karin E. Bauch; Aleksandra N. Stojic; Jörn Helbert
We analyzed plagioclase feldspar samples that were well-characterized in terms of chemical composition as well as degree of Al,Si order in mid-infrared reflection spectra between 7 μm and 14 μm (1429 cm−1 and 714 cm−1). The chemical compositions were derived with an electron microprobe analyzer. To determine the degree of Al,Si order, powder X-ray diffraction methods were applied. For the interpretation
-
Effects of heterogeneous gouge segments on the slip behavior of experimental faults at dm scale Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-27 L. Buijze; Y. Guo; A.R. Niemeijer; S. Ma; C.J. Spiers
Frictional heterogeneity within fault zones is one of the factors proposed to explain the spectrum of slow, intermediate, and fast slip behaviors exhibited by faults in nature. Numerical modeling shows how even a simplified model setup incorporating sliding on a velocity-weakening (VW) patch surrounded by velocity-strengthening (VS) material can reproduce a rich variety of slip behaviors resembling
-
Regional patterns and temporal evolution of ocean iron fertilization and CO2 drawdown during the last glacial termination Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-27 Fabrice Lambert; Natalia Opazo; Andy Ridgwell; Gisela Winckler; Frank Lamy; Gary Shaffer; Karen Kohfeld; Rumi Ohgaito; Samuel Albani; Ayako Abe-Ouchi
The last time Earth's climate experienced geologically rapid global warming was associated with the last glacial termination, when atmospheric CO2 concentrations rose from 180 ppmv during the Last Glacial Maximum (LGM, 26-19 kaBP) to ∼260 ppmv by the early Holocene (12-8 kaBP). About one quarter of that difference is thought to be due to a stronger biological pump during glacial times, driven by increased
-
The influence of deep water circulation on the distribution of 231Pa and 230Th in the Pacific Ocean Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-27 Yiming Luo; Jörg Lippold; Susan E. Allen; Jerry Tjiputra; Samuel L. Jaccard; Roger Francois
Sedimentary 231Pa/230Th ratios have been used in the Atlantic Ocean as a proxy to reconstruct past changes in the strength and geometry of the Atlantic Meridional Overturning Circulation (AMOC), stemming from the southward export of 231Pa by the North Atlantic Deep Water (NADW). However, deep waters in the Pacific Ocean have a longer residence time, so that Pacific sedimentary 231Pa/230Th ratios are
-
Field-based measurements of volcanic ash resuspension by wind Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-27 E. Del Bello; J. Taddeucci; J.P. Merrison; K.R. Rasmussen; D. Andronico; T. Ricci; P. Scarlato; J.J. Iversen
The resuspension of volcanic ash by wind is a significant source of hazard during and after volcanic eruptions. Parameterizing and modeling ash resuspension requires direct measurement of the minimum wind shear stress required to move particles, usually expressed as the threshold friction velocity U⁎th, a parameter that, for volcanic ash, has been measured only scarcely and always in the laboratory
-
Controls on boron isotopes in a cold-water coral and the cost of resilience to ocean acidification Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-26 Alexander C. Gagnon; Anne M. Gothmann; Oscar Branson; James W.B. Rae; Joseph A. Stewart
-
Time-resolved grain-scale 3D imaging of hydrofracturing in halite layers induced by gypsum dehydration and pore fluid pressure buildup Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-26 S. Marti; F. Fusseis; I.B. Butler; C. Schlepütz; F. Marone; J. Gilgannon; R. Kilian; Y. Yang
Fluid release from dehydration reactions is considered to have significant effects on the strength and dynamics of tectonic faults at convergent plate boundaries. It is classically assumed that the production of fluid leads to increased pore fluid pressures that perturb a fault's stress state and thereby facilitates and enhances deformation. This important assumption has never been supported by direct
-
Quantifying strong seismic propagation effects in the upper volcanic edifice using sensitivity kernels Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-26 Beatriz Martínez Montesinos; Christopher J. Bean; Ivan Lokmer
-
Carbon partitioning between metal and silicate melts during Earth accretion Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-25 Carolin E. Fichtner; Max W. Schmidt; Christian Liebske; Anne-Sophie Bouvier; Lukas P. Baumgartner
In the accreting Earth and planetesimals, carbon was distributed between a core forming metallic melt, a silicate melt, and a hot, potentially dense atmosphere. Metal melt droplets segregating gravitationally from the magma ocean equilibrated near its base. To understand the distribution of carbon, its partitioning between the two melts is experimentally investigated at 1.5–6.0 GPa, 1300–2000 °C at
-
A condensation origin for the mass-dependent silicon isotopic variations in Allende components: implications for complementarity Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-25 Rayssa Martins; Marc Chaussidon; Zhengbin Deng; Francesco Pignatale; Frédéric Moynier
Primitive chondrites have bulk compositions close to that of the solar photosphere, with however significant variations of elemental ratio relative to the solar composition, depending on the volatility of the elements considered. This is classically understood as indicating a primary geochemical signature due to the formation of the components of chondrites (refractory inclusions, chondrules and matrix)
-
On the fate of impact-delivered metal in a terrestrial magma ocean Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-24 Christian Maas; Lukas Manske; Kai Wünnemann; Ulrich Hansen
Impacts on Earth crucially influenced core formation and the subsequent evolution of Earth's mantle and may have contributed to late accretion of material. However, to what extent the present-day geochemical signature of Earth's mantle reflects the processes of core formation and late accretion, and how much of material delivered by giant impacts and by impacts of smaller projectiles during late accretion
-
Fe–Mg interdiffusion in wadsleyite and implications for water content of the transition zone Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-24 Baohua Zhang; Chengcheng Zhao; Takashi Yoshino
Fe–Mg interdiffusion rates in polycrystalline wadsleyite aggregates have been determined as a function of water content (up to ∼0.345 wt.% H2O) at 16 GPa and 1373–1773 K in a Kawai-type multi-anvil apparatus. Pre-synthesized water-poor and -rich polycrystalline wadsleyite were used as starting materials. Diffusion profiles were obtained across the interface between Fe-free and -bearing diffusion couples
-
Water isotopic constraints on the enhancement of the mid-Holocene West African monsoon Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-23 Alexander J. Thompson; Clay R. Tabor; Christopher J. Poulsen; Christopher B. Skinner
During the early to mid-Holocene, changes in orbital precession led to considerable increases in West African monsoon (WAM) rainfall compared to today and shifted its reach further north. However, climate proxies and paleoclimate model simulations disagree over fundamental aspects of the mid-Holocene (MH; 6 ka BP) enhancement of the WAM. Here, we use a water isotope-enabled Earth system model (iCESM1)
-
The impact of Snowball Earth glaciation on ocean water δ18O values Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-23 William F. Defliese
It has been long recognized that glacial episodes can affect the δ18O value of ocean water, where preferential storage of 16O in ice changes the 18O/16O ratio of the ocean. However, these effects are generally thought of as transient, as Cenozoic glaciation has had neither the magnitude or duration to cause long-term change with ocean water buffered to values close to 0±2‰ VSMOW by tectonic processes
-
Limited iodate reduction in shipboard seawater incubations from the Eastern Tropical North Pacific oxygen deficient zone Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-20 D.S. Hardisty; T.J. Horner; N. Evans; R. Moriyasu; A.R. Babbin; S.D. Wankel; J.W. Moffett; S.G. Nielsen
The relative abundance of the inorganic iodine species, iodide and iodate, are applied to characterize both modern and ancient marine oxygen deficient zones (ODZs). However, the rates and mechanisms responsible for in situ iodine redox transformations are poorly characterized, rendering iodine-based redox reconstructions uncertain. Here, we provide constraints on the rates and mechanisms of iodate
-
Measuring multiple cosmogenic nuclides in glacial cobbles sheds light on Greenland Ice Sheet processes Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-20 Lee B. Corbett; Paul R. Bierman; Thomas A. Neumann; Joseph A. Graly; Jeremy D. Shakun; Brent M. Goehring; Alan J. Hidy; Marc W. Caffee
The behavior of the Greenland Ice Sheet during the Pleistocene remains uncertain due to the paucity of evidence predating the Last Glacial Maximum. Here, we employ a novel approach, cosmogenic nuclide analysis of individual subglacially-derived cobbles, which allows us to make inferences about ice sheet processes and subglacial erosion. From three locations in western Greenland, we collected 86 cobbles
-
High-resolution interannual precipitation reconstruction of Southern California: Implications for Holocene ENSO evolution Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-19 Xiaojing Du; Ingrid Hendy; Linda Hinnov; Erik Brown; Jiang Zhu; Christopher J. Poulsen
The variability of El Niño-Southern Oscillation (ENSO) on centennial to millennial time-scales is poorly understood due to the insufficient length, continuity, or resolution of existing paleoclimate records. Here we present a new, continuous, sub-annually resolved scanning XRF Ti record from marine sediments collected from Santa Barbara Basin (SBB) to reveal interannual precipitation changes in Southern
-
Overspilling small craters on a dry Mars: Insights from breach erosion modeling Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-19 A.O. Warren; S. Holo; E.S. Kite; S.A. Wilson
Understanding when, where, and how frequently liquid water was stable on Mars since the Late Noachian/Early Hesperian (3.2-3.9 Ga) is important for understanding the evolution of Mars' climate and hydrology. Some relatively young features on Mars require multiple wetting events to form, whereas others are consistent with single wetting events. Small and rare exit breach craters or “pollywogs” are craters
-
Miocene to present oceanographic variability in the Scotia Sea and Antarctic ice sheets dynamics: Insight from revised seismic-stratigraphy following IODP Expedition 382 Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-19 Lara F. Pérez; Yasmina M. Martos; Marga García; Michael E. Weber; Maureen E. Raymo; Trevor Williams; Fernando Bohoyo; Linda Armbrecht; Ian Bailey; Stefanie Brachfeld; Anna Glüder; Michelle Guitard; Marcus Gutjahr; Sidney Hemming; Iván Hernández-Almeida; Frida S. Hoem; Yuji Kato; Suzanne O'Connell; Xufeng Zheng
Scotia Sea and the Drake Passage is key towards understanding the development of modern oceanic circulation patterns and their implications for ice sheet growth and decay. The sedimentary record of the southern Scotia Sea basins documents the regional tectonic, oceanographic and climatic evolution since the Eocene. However, a lack of accurate age estimations has prevented the calibration of the reconstructed
-
Northwest Pacific ice-rafted debris at 38°N reveals episodic ice-sheet change in late Quaternary Northeast Siberia Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-18 A.P. McCarron; G.R. Bigg; H. Brooks; M.J. Leng; J.D. Marshall; V. Ponomareva; M. Portnyagin; P.J. Reimer; M. Rogerson
The ice-rafted-debris (IRD) record of the open Northwest Pacific points towards the existence of substantial glacial ice on the Northeast Siberian coast during the late Quaternary. However, the scale and timing of glaciation and de-glaciation remains controversial due to the dearth of both onshore and offshore records. Existing IRD data suggests at least one event of dynamic and abrupt change during
-
Theoretical versus empirical secular change in zircon composition Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-18 Christopher L. Kirkland; Chris Yakymchuk; Hugo K.H. Olierook; Michael I.H. Hartnady; Nicholas J. Gardiner; Jean-François Moyen; R. Hugh Smithies; Kristoffer Szilas; Tim E. Johnson
We generate theoretical curves for zircon growth during cooling of tonalitic and A-type granitic magmas and compare these with empirical Ti-in-zircon populations from the Paleoarchean Pilbara Craton, Australia, Mesoarchean Akia Terrane, Greenland, and the Mesoproterozoic Musgrave Province, Australia. Our models predict variable zircon growth rates on magma cooling dependant on magma composition, crystallizing
-
Astronomical forcing of lake evolution in the Lanzhou Basin during early Miocene period Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-18 Zhixiang Wang; Ze Zhang; Chunju Huang; Jiangming Shen; Yu Sui; Zhiqi Qian
Orbital-scale East Asian summer monsoon (EASM) variability has been extensively investigated in Pliocene-Quaternary loess and marine sediments. In recent years, middle-late Miocene orbital-scale EASM variability has been depicted in lacustrine deposits from NE Tibetan basins, showing a dominant cyclicity of ∼100 kyr eccentricity. However, EASM variability during the early Miocene time remains poorly
-
Apatite (U-Th-Sm)/He date dispersion: First insights from machine learning algorithms Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-17 Alice Recanati; Nistor Grozavu; Younes Bennani; Cécile Gautheron; Yves Missenard
Numerous parameters impact apatite (U-Th-Sm)/He (AHe) thermochronological dates, such as radiation damage, chemical content, crystal size and geometry, and their knowledge is essential for better geological interpretations. The present study investigates a new method based on advanced data mining techniques, to unravel the parameters that could play a role in He retention and thus on AHe date. The
-
Temperature signals of ice core and speleothem isotopic records from Asian monsoon region as indicated by precipitation δ18O Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-17 Wusheng Yu; Tandong Yao; Lonnie G. Thompson; Jean Jouzel; Huabiao Zhao; Baiqing Xu; Zhaowei Jing; Ninglian Wang; Guangjian Wu; Yaoming Ma; Jing Gao; Xiaoxin Yang; Jingyi Zhang; Dongmei Qu
Ice cores and speleothem δ18O records from Asia have been widely used as a proxy to reconstruct paleoclimate changes. However, whether those δ18O records are a proxy of temperature or monsoon intensity has remained a great controversy. Generally, ice core δ18O records from non-monsoon and transition regions indicate temperature, but ice core and speleothem δ18O records from monsoon regions have been
-
Centimeter-resolution topographic modeling and fine-scale analysis of craters and rocks at the Chang'E-4 landing site Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-16 Bo Wu; Yuan Li; Wai Chung Liu; Yiran Wang; Fei Li; Yang Zhao; He Zhang
Chang'E-4 was the first lunar mission to successfully land on the far side of the Moon. The stereo images collected by the panoramic camera (Pancam) mounted on the Jade Rabbit-2 rover have provided the most detailed in situ observations of the landing site along the rover traverse. This paper presents our efforts in centimeter-resolution topographic modeling and fine-scale analysis of craters and rocks
-
Explosivity of basaltic lava fountains is controlled by magma rheology, ascent rate and outgassing Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-16 G. La Spina; F. Arzilli; E.W. Llewellin; M.R. Burton; A.B. Clarke; M. de' Michieli Vitturi; M. Polacci; M.E. Hartley; D. Di Genova; H.M. Mader
-
Global zircon analysis records a gradual rise of continental crust throughout the Neoarchean Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-16 Jesse Ray Reimink; Joshua H.F.L. Davies; Alessandro Ielpi
Determining when continental masses emerged above the global ocean is crucial to understanding secular changes in crustal and Earth-surface processes. The emergence of continents above sea level provided important sinks for atmospheric CO2, a source of bioavailable P2O5, and initiated the erosional component of the rock cycle. Previous estimates for continental emergence vary widely and depend on complex
-
Partial melting of ultrahigh-pressure eclogite by omphacite-breakdown facilitates exhumation of deeply-subducted crust Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-16 Peng Feng; Lu Wang; Michael Brown; Tim E. Johnson; Andrew Kylander-Clark; Philip M. Piccoli
Results from numerical modelling and experimental petrology have led to the hypothesis that partial melting was important in facilitating exhumation of ultrahigh-pressure (UHP) metamorphic rocks from mantle depths. However, the melting reactions responsible are rarely well-documented from natural examples. Here we report microstructural features and compositional data that indicate in situ partial
-
Billion-year exposure ages in Gale crater (Mars) indicate Mount Sharp formed before the Amazonian period Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-16 Peter E. Martin; Kenneth A. Farley; Charles A. Malespin; Paul R. Mahaffy; Kenneth S. Edgett; Sanjeev Gupta; William E. Dietrich; Michael C. Malin; Kathryn M. Stack; Paulo M. Vasconcelos
The erosion rates and mechanisms operating on Mount Sharp in Gale crater, Mars were assessed via experiments performed by the SAM instrument to determine the cosmogenic noble gas contents of Murray mudstone formation samples Mojave 2 and Quela. Previous measurements of samples from the Aeolis Palus depression between Mount Sharp and the north rim of Gale crater indicate that scarp retreat-generated
-
Chronology of serpentinization: Paleomagnetic evidence for 20 Ma serpentinization of the Oeyama ophiolite, Wakasa, Southwest Japan Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-12 Yo-ichiro Otofuji; Makoto Fujihara; Koji Uno
Serpentinization of mantle peridotite generates magnetite that is able to acquire a remanent magnetization parallel to the ambient geomagnetic field. The paleomagnetic direction of serpentine provides insights as to the timing of serpentinization. This study examines paleomagnetic properties of serpentine in the Paleozoic Oeyama ophiolite in Wakasa (35.39°N, 134.39°E), Southwest Japan. Reversed polarity
-
Early deglacial CO2 release from the Sub-Antarctic Atlantic and Pacific oceans Earth Planet. Sci. Lett. (IF 4.823) Pub Date : 2020-11-10 R. Shuttleworth; H.C. Bostock; T.B. Chalk; E. Calvo; S.L. Jaccard; C. Pelejero; A. Martínez-García; G.L. Foster
Over the last deglaciation there were two transient intervals of pronounced atmospheric CO2 rise; Heinrich Stadial 1 (17.5-15 kyr) and the Younger Dryas (12.9-11.5 kyr). Leading hypotheses accounting for the increased accumulation of CO2 in the atmosphere at these times invoke deep ocean carbon being released from the Southern Ocean and an associated decline in the global efficiency of the biological
Contents have been reproduced by permission of the publishers.