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 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

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

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

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

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

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.

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

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

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

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

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

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

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

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 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

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

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

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

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

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

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

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

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

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.

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

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

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

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

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

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

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

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

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

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)

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 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

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)

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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