Marine dissolved organic matter (DOM) is one of the largest reservoirs of organic carbon and nitrogen in the world. Yet, despite its global importance, most DOM remains molecularly uncharacterized. Solid-state nuclear magnetic resonance (NMR) spectroscopy of isolated DOM fractions represents one of the most powerful techniques to understand overall structural composition. However, it is well known

Tektites are reduced (Fe2+) glasses formed by the quenching of molten material ejected from Earth’s surface as a result of a hypervelocity impact. The vast majority of tektites are usually homogeneous glasses, but rare samples containing mineral inclusions can provide insights about the source material, sample thermal history, and tektite formation process. Tektites from two distinct strewn fields

The Urucum iron- and manganese formation (IF-MnF) in the Santa Cruz Formation, Brazil, was deposited in a glacially influenced, late Neoproterozoic depositional environment. It has proven to be a reliable and robust archive for the late Neoproterozoic, allowing unique insights into the composition of seawater during an interval that is characterized by dramatic changes in the Earth’s litho-, hydros-

Autochthonous dissolved organic matter (Auto-DOM) produced by a biological carbon pump using dissolved inorganic carbon (DIC) from carbonate weathering plays an important role in carbon cycling within inland waters. However, little is known regarding how environmental conditions impact the composition and fate of organic matter, especially in surface waters of the semi-arid Loess Plateau, which is

Olivine, typically occurring as a forsterite-fayalite solid solution, is a major rock-forming mineral in mafic and ultramafic igneous rocks, and it is important for understanding the genesis, evolution, and alteration of its host rocks. In this study, both GGA and GGA + U methods were employed to calculate the reduced partition function ratios of Fe, Mg, O, and Si isotopes for the forsterite-fayalite

Cobalt (Co) and nickel (Ni) are critical metals for modern renewable energy technologies as well as essential micronutrients for terrestrial plant health and marine primary production. Both metals are commonly surface-adsorbed onto and/or structurally-incorporated into iron (oxyhydr)oxide minerals, such as goethite (α-FeOOH), that are ubiquitously present in soils and sediments at the Earth’s surface

Excesses of cosmic-ray produced nuclei in individual components of meteorites indicate “pre-irradiation”, either in the surface region of their parent bodies or as free-floating small particles in the early Solar System. We expand on our earlier work (Beyersdorf-Kuis et al., 2015) and report a study of cosmic-ray produced He and Ne in chondrules and “matrix” (i.e., matrix-dominated) material of several

Crystalline calcium carbonate isotope compositions have been widely used to reconstruct past environments. However, if their isotopic compositions are modified because of crystallization from an amorphous precursor, their reliability as paleo-geochemical proxies can be compromised. This study explored the changes in the oxygen isotope compositions during the transformation of amorphous calcium carbonate

Zn/FeT (FeT=Fe2+ + Fe3+) ratios in primitive melts have been proposed as a redox proxy to assess the redox states of the upper mantle. However, to effectively use the melt Zn/FeT ratio as a redox proxy, it is necessary to compare variations of melt Zn/FeT ratios induced by changes in oxygen fugacity (fO2) with variations due to changes in Zn-Fe contents and mineralogy of the sources. Here we show that

The geochemical characterization of phytoplankton-derived organic compounds found in marine sediments has been widely used to reconstruct atmospheric pCO2 throughout the Cenozoic. This is possible owing to a well-established relationship between the carbon isotope ratios of phytoplankton biomass and CO2 concentration in the ambient seawater. An ideal molecular target for such proxy reconstructions

Most of the solidification history of magmas beneath active volcanoes takes place in chemically and physically perturbed plumbing systems where the growth of crystals is collectively governed by a range of kinetic processes related to the dynamics of crustal reservoirs and eruptive conduits. In this context, we have experimentally investigated the partitioning of major, minor, and trace cations between

This study explores the estimation of solubility-induced elemental fractionation of noble gases in hydrocarbon-based oils through existing empirical and theoretical models, complemented by a novel molecular simulation-based approach. Quantifying such fractionation is essential for a deeper understanding of fluid processes and migration in subsurface geological resources, an area currently lacking in

Pleistocene loess records of the Khovaling Loess Plateau (KLP) in Tajikistan provide rich collections of lithic artifacts demonstrating past human presence in the region. To understand the timing of human activity and environmental conditions prevailing at that time U–Th dating and clumped/stable C/O isotope measurements have been applied to modern and Pleistocene soil carbonates (SCs) collected at

Helium isotopes are unrivalled tracers of the origins of melts in the Earth’s convecting mantle but their role in determining melt contributions from the shallower and rigid lithospheric mantle is more ambiguous. We have acquired new 3He/4He data for olivine and pyroxene separates from 47 well-characterised mantle xenoliths from global on- and off-craton settings. When combined with existing data they

Biotransformation of ferrihydrite (Fh) by dissimilatory iron-reducing bacteria (DIRB) into various secondary minerals assemblages widely occurs in anaerobic environments. While respiration-driven supply rates of Fe(II) have been proposed as a primary factor controlling kinetics and mineral products of this process, the specific mechanism by which DIRB respiration rates regulate Fh biotransformation

Apatite is ubiquitous in lunar samples and has been used widely for estimating volatile abundances in the lunar interior. However, apatite compositional and isotopic variations within and between samples have resulted in varying and ambiguous results. Understanding apatite petrogenesis will help with both identifying the appropriate composition for volatile estimation and interpreting isotopic variations

We report the results of coordinated mineralogical, microstructural, and oxygen isotopic analyses of grossite-bearing refractory inclusions from reduced CV (Vigarano type) chondrites to obtain a more complete picture of secondary parent body alteration processes and conditions. Grossite (CaAl4O7) occurs in cores of nodules in fine-grained Ca,Al-rich inclusions (CAIs) that likely represent aggregates

Among carbonaceous chondrites, the chondrules of CB and CH stand out by being dominated by skeletal barred olivine and cryptocrystalline textures. These non-porphyritic chondrules are thought to have formed within an impact-generated plume resulting from large-scale asteroidal collisions late in disk history. Porphyritic chondrules are also present, if rare, in CB and CH chondrites and might correspond

Heterogeneities in the phosphorus (P) content of olivine are relatively resistant to diffusive homogenization when compared with other compositional heterogeneities. Thus, heterogeneities in the spatial distribution of P can preserve petrological information about olivine crystals from the earliest stages of crystallization which have been otherwise eliminated. However, compared to independent determinations

Despite the importance of alkaline seafloor hydrothermal vents in broadening our understanding of deep-sea hydrothermal ecosystems, little is known about the mobility and concentrations of micronutrient transition metals in these environments. Here, we present new analyses of micronutrient transition metal concentrations in vent fluids from the iconic Lost City Hydrothermal Field (LCHF) and report

The production of methane in coastal sediments and its release to the water column is intensified by anthropogenic eutrophication and bottom water hypoxia, and it is still uncertain whether methane emissions to the atmosphere will be enhanced. Here, we assess seasonal variations in methane dynamics in a eutrophic, seasonally euxinic coastal basin (Scharendijke, Lake Grevelingen). In-situ benthic chamber

Some young volcanic rocks have been found to possess intrasample Os-isotope heterogeneity. This has important implications for source tracing and dating. Here, we use a new procedure through which it is possible to sequentially extract, from a single aliquot, the Os/Os ratio of: i) the surface contaminant(s) (hydrobromic acid leachate); ii) the residual bulk rock powder (Step I) and iii) the Os-bearing

The processes responsible for the isotopic compositions and abundances of volatile elements in the early solar system remain highly debated. Orders of magnitude variation of (highly) volatile elements exist between different magmatic iron meteorite groups, but it is unclear to what extent their depletions can be explained by evaporation from metal melts during parent body accretion and/or subsequent

Stable isotope ratios of C1–C5 alkanes, the major constituents of subsurface gaseous hydrocarbons, can provide valuable insights on their origins, transport, and fates. Equilibrium isotope effects are fundamental to interpreting stable isotope signatures, as recognition of them in natural materials indicates reversible processes and constrains the temperatures of equilibrated systems. Hydrogen isotope

Gold solubility was measured at temperatures of 350, 400, 450, and 490 °C and pressures of 500 and 1000 bar in an ’oxidized sulfide’ system, as a function of pHT (2 – 10) and sulfur concentration (m(Stotal) = 0.03 – 1.2 [mol·(kg H2O)-1]). In this system, sulfur primarily exists as H2S, H2SO3, H2SO4, their dissociation products, and radical species such as S2- and S3-. The complexes Au(HS)2-, Au2S22-

Constraining the processes that fractionate barium isotopes is essential for utilising barium isotope ratios as environmental tracers. Barium concentration measurements from soils, rivers, and estuaries demonstrate that adsorption–desorption reactions significantly influence the distribution of fluid–mobile barium at the Earth’s surface, potentially driving isotopic fractionation. To quantify the direction

Serpentinite dehydration in subduction zones plays a pivotal role in geochemical cycling on Earth. A number of geochemical studies on arc magmas have elucidated the contributions of serpentinite-derived fluids to mantle sources. However, due to complex geological overprints during subduction zone processes, discerning serpentinite signatures in exposed metamorphic rocks within fossil subduction zones

Adsorptive fractionation and oxidation of dissolved organic matter (DOM) on manganese (Mn) oxide surfaces alter the molecular composition and stability of DOM, but the impact of iron (Fe) oxides on the coupled adsorption-oxidation processes of DOM by Mn oxides is largely unknown. In this study, the underlying mechanisms of molecular transformation of DOM on birnessite (Bir) in the presence of ferrihydrite

The global carbon and iron cycles are intimately linked as redox-sensitive iron oxides readily bind organic carbon in a variety of environmental settings, including marine and lacustrine sediments. While these iron-organic carbon complexes sequester vast quantities of organic carbon, the composition of the organic matter within them remains unknown for lacustrine environments. Here we present C K and

Reversible adsorption and isotope fractionation of boron on the surface of clay minerals is a key process that impacts boron isotope cycling in porewater, rivers and the ocean. However, the differences in boron isotope fractionation factors between various clay minerals and their dependence on fluid chemistry are not well known. We performed two sets of experiments, using solutions of pure water with

Aqueous alteration in planetesimals is one of the earliest geological processes in the solar system. The timing of aqueous alteration sheds light on the timescale of material evolution through water–rock interaction in small bodies. The Mn-Cr decay system, where a short-lived radionuclide Mn decays to Cr with a half-life of 3.7 Myr, is a powerful tool for dating carbonates in primitive meteorites that

Chemical and isotopic measurements of HIDALGO, a stoichiometrically pure hibonite inclusion found in the matrix of the Dar al Gani 027 meteorite, were conducted by secondary ion mass spectrometry to investigate its origin and evolution. HIDALGO is characterized by large mass-dependent isotope fractionations in O, Ca, and Ti, as well as large negative anomalies in neutron-rich Ca and Ti, making it the

By taking advantage of recent analytical advances, we herein develop the Ra/Th isotope systematics as a novel tool for quantifying nitrate and dissolved silicate fluxes across the sediment–water interface of the deep-ocean floor. Sediment cores were retrieved from the seabed between 4927 m and 5951 m in the North Pacific Ocean. Downcore profiles of Th and both dissolved and total Ra were measured using

The ungrouped dunitic achondrite Northwest Africa (NWA) 12217 contains symplectic spinel-pyroxene veins that are mineralogically identical to symplectites in other ultramafic planetary materials. The morphology and amount of chromite present in these features relative to the Cr in their olivine hosts suggest an exogenous origin. Petrological experiments show that a Cr laden sulfide liquid reacts with

Establishing the temporal evolution of the ureilite parent body(ies) is crucial for understanding the quantitative timescale of planetesimal formation and evolution in the protoplanetary disk. In order to establish a timeline for these early processes, age constraints on the accretion, differentiation and secondary reduction were obtained with the short-lived Mn-Cr chronometer to whole-rock and sequentially

Nb and Ta are geochemical twins, yet their ratio varies considerably in igneous rocks. It is generally supposed that felsic melts coexisting with residual rutile will have elevated Nb/Ta ratios relative to their basalt precursors, which is pivotal to our understanding of deep crustal melting and continent formation throughout Earth’s history. This study reports petrological, bulk-rock and mineral geochemical

I have done major element analyses by electron microprobe, in-situ trace element analyses by laser ablation inductively coupled plasma mass spectrometry, and instrumental neutron activation analyses on bulk samples of olivine grains separated from main-group and Eagle-Station pallasites. Most main-group pallasite olivines have homogeneous Fe/Mg yet have varying Fe/Mn. Those few with anomalously ferroan

Titanium (Ti), a typical rock-forming element, is traditionally considered to be lithophile, incompatible, and fluid-immobile, and is recognized as a significant proxy for understanding the oceanic environments, such as the content of terrestrial materials in modern marine sediments. However, recent investigations have revealed the production of various titania minerals through the alteration of volcanic

Ocean temperature, redox state, circulation, and nutrient levels regulate the marine nitrogen (N) cycle, yet their specific impacts during greenhouse intervals remain poorly understood. Here, we examined the Smithian–Spathian hyperthermal event (∼250.5 Ma) during the Early Triassic greenhouse using stable N isotopes (δN) from sedimentary records in the Nanpanjiang Basin and Northern Yangtze Basin of

The degree of oxygenation of the marine water column and sediments has a major impact on the dynamics of biogeochemical cycles and habitability for life. Reconstructing past changes in marine oxygenation through time is therefore crucial for our understanding of the evolution of Earth’s system and Life. Although a range of inorganic and organic proxies exist to reconstruct changes in water column and/or

Magmatic-hydrothermal processes associated with granitic rocks are crucial for magma evolution and rare metal enrichment. This study presents Rb isotope compositions (δRb) for whole rocks and Rb-enriched minerals (biotite and K-feldspar) from the Qitianling granite pluton in South China, which hosts one of the world’s largest Sn-ore deposits. This pluton comprises three stages of granitic evolution

Extracellular antibiotic resistance genes (eARGs) are ubiquitous in the environment and serve as an important source for horizontal transfer in bacterial populations, which can be negated by strong binding of eARGs with iron(hydr)oxides. However, microbial reductive dissolution of iron(hydr)oxides is very common in nature and its effect on the fate and horizontal transfer potential of eARGs bound to

Chondrules and Ca-Al-rich inclusions (CAIs) have been considered characteristic constituents of chondritic meteorites, although the outward transportation of CAIs has been theoretically pointed out. Stardust samples recovered by the Stardust mission from the 81P/Wild2 comet contained chondrule-like objects (CLOs) and refractory inclusions that include CAIs and amoeboid olivine aggregates (AOAs). However

Magmatic activity can be monitored through the chemical variations of volcanic lakes. While those lakes can be influenced by direct magmatic input, water-rock interaction processes in hydrothermal system also have a large influence. Disentangling those effects is critical to use crater lakes for volcanic activity monitoring purposes. Zinc is a volatile metal that is easily degassed and can be incorporated

We present a suite of major element stable isotope (δC, δO, δCa, δMg), and selected trace element (Sr/Ca and Mg/Ca) data from Pleistocene sediments from the Great Barrier Reef (IODP Expedition 325), as well as Holocene surface sediments from the Bahamas (Triple Goose Creek, Andros Island) to identify geochemical fingerprints associated with early marine and meteoric diagenesis. Sediments from both

Experimental investigation of the fractionation behavior of Cu isotopes during the replacement of pyrite by Cu-bearing sulfides (chalcopyrite, bornite, and chalcocite) was conducted under hydrothermal conditions. At the initial stages of the replacement reaction, small mounds of product formed on the pyrite surface; these mounds then grew and coalesced, progressively covering the pyrite grains as the

Ferruginous conditions, defined by anoxia and abundant dissolved ferrous iron (Fe), dominated the Precambrian oceans but are essentially non-existent in a modern, oxygenated world. Ferruginous meromictic lakes represent natural laboratories to ground truth our understanding of the stable Fe isotope proxy, which has been used extensively in interpreting the origins of Fe-rich sedimentary rocks like

We apply the stable potassium isotope system (K/K) to well-studied Mariana arc lavas, in which inter-island geochemical variability has been interpreted to reflect near constant addition of an aqueous fluid flux, that dominantly samples the subducting mafic oceanic crust and variable amounts of sediment melt addition to the sub-arc mantle wedge. The nature of the sediment component in the Mariana arc

The sulfur over calcium ratio (S/Ca) in foraminiferal shells was recently proposed as a new and independent proxy for reconstructing marine inorganic carbon chemistry. This new approach assumes that sulfur is incorporated into CaCO predominantly in the form of sulfate (SO) through lattice substitution for carbonate ions (CO), and that S/Ca thus reflects seawater [CO]. Although foraminiferal growth

Zircon and other U-bearing accessory phases are important time-capsules for studying the evolution of Earth and other planetary bodies as these minerals can record both temporal and compositional information regarding their host rocks. In silicate melts, uranium can occur in either the U, U, or U valence state and its redox sensitive nature could, in principle, allow for information on magma oxygen

Seafloor hydrothermal venting may be an important source of marine Cu and affect the biogeochemical cycling of Cu in the oceans. The distribution of Cu and its isotope compositions (δCu) can provide insight into seafloor hydrothermal processes and their role in the mass balance of global Cu. To date, there are no published Cu isotope data for hydrothermal plumes and very few reports on Cu concentration

Sediment residence time (SRT) is a key parameter of the Earth’s surface system, bridging the realms of sediment transport, biogeochemical cycles, sedimentary archives, and watershed management. SRT in mountainous catchments includes the time particles have spent in the subsurface weathering zone, which has been challenging to measure thus limiting our understanding of the magnitude and controlling

Stable Sn isotope ratios are emerging as a novel tracer for a wide range of geological processes; however, the Sn isotopic baseline of the upper continental crust (UCC) is not yet well-constrained. Here, we report high-precision Sn isotope data of a wide range of UCC samples, including granites, pegmatites, and sediments, to document the Sn isotopic composition of UCC. Significant variations in δSn

Jarosite, a prominent mineral in oxidised acid sulfate soil, is known to sorb and incorporate a variety of elements, including Al. However, to understand the role that jarosite plays in regulating element cycles, it is crucial to understand the stability and transformation pathways of jarosite in an acid sulfate soil under dynamic biogeochemical conditions. In this study, we observed the transformation

Magmatic iron meteorites are thought to sample the metallic cores of differentiated planetesimals and are subdivided into several chemical groups, each representing a distinct parent body. The only exceptions are the groups IIAB and IIG, which have been proposed to sample two immiscible melts from the same core. To test this model, we report the first Fe, Ni, O, and Cr isotope data for IIG iron meteorites

The alteration of ocean crust through hydrothermal seawater circulation facilitates chemical exchange between Earth’s surface and interior. Hydrothermal alteration leads to uranium (U) removal from seawater and net U uptake by the ocean crust, particularly during low temperature alteration that occurs on the vast ocean ridge flanks away from the spreading axes. Determining the timescales of U uptake

Mars has experienced drastic environmental evolution in terms of pH, redox, and desiccation. NASA’s Curiosity rover discovered that the sediments of the Pahrump Hills member of the Murray formation in Gale Crater contained different redox states of Fe oxides. To interpret the observations, understanding the factors that control iron redox states within early Gale lakes on Mars is needed. Here, we present

In Earth’s crust, thermochemical sulfate reduction (TSR) is a common organic–inorganic interaction, which is in close association with the carbon cycle in sedimentary basins and metal sulfide precipitation in Mississippi Valley-type deposits. However, the reaction pathway and mechanism of TSR need further investigation, mainly due to the complex sulfur species involved in this reaction. Here we applied

Abiotic synthesis of CH in seafloor hydrothermal fluids is generally assumed to occur heterogeneous reactions on mineral surfaces. Stepwise homogeneous reduction of CO has, however, been suggested as an alternative (but sluggish) abiotic pathway to CH, potentially via metastable species of intermediate oxidation states. In this study, we examine the effect of two temperature-dependent methylated species