Most of the World’s large tungsten deposits are genetically related to fluorine-rich granitic magmas, their ores contain fluorine minerals, such as fluorite and topaz, and their host rocks have commonly undergone fluorine metasomatism to form greisens. In view of this evidence that tungsten ore fluids are enriched in fluorine, and the potential for fluoride to form stable complexes with hard acids

Meteorites contain prebiotic, bio-relevant organic compounds including amino acids. Their syntheses could result from diverse sources and mechanisms and provide a window on the conditions and materials present in the early solar system. Here we constrain alanine’s synthetic history in the Murchison meteorite using site-specific 13C/12C measurements, reported relative to the VPDB standard. The δ13CVPDB

Constraining the behaviour of Re and Os during eclogite melting is required to understand the Re and Os budget and 187Os/188Os of recycled slabs produced at warm subduction zones. It is particularly relevant to early Earth history, a period during which slab melting could have prevailed over dehydration due to higher mantle temperatures. There are however currently few constraints on Re and Os mobility

Constraining the formation age of individual diamonds from incorporated mineral inclusions and assessing the host diamonds’ geochemical characteristics allows determination of the complex history of diamond growth in the sub-continental lithospheric mantle (SCLM). It also provides the rare opportunity to study the evolution of the deep cycling of volatiles over time. To achieve these aims, Sm-Nd isotope

Methyl groups are found in numerous biogenic and synthetic materials including geologically preserved materials such as wood. The carbon and hydrogen isotope compositions of methyl groups are used as tracers in biogeochemical cycles, as paleothermometers, and to determine the hydrogen isotopic composition of ancient rain. Here we present analyses of resolved 13C–D (13CH2D) and D–D (12CHD2) clumped

To better understand the role and extent of inter-mineral diffusion during subsolidus processes, we investigated the iron and magnesium isotopic compositions of olivine, orthopyroxene, and chromite separates from the Peridotite Zone of the Stillwater Complex. Olivine and orthopyroxene show limited Mg isotopic variations, with δ26Mg values ranging from −0.40 to −0.26‰ and from −0.29 to −0.22‰, respectively

Chromium (Cr) isotopes play an important role in cosmochemistry and planetary science, because they are powerful tools for dating (53Mn-53Cr short-lived chronometry), tracing (54Cr nucleosynthetic anomalies) the origins of the materials, and studying the processes involved in volatile element fractionation and planetary differentiation (Cr stable isotopic fractionation). The foundation for using Cr

Crystal-melt separation is important for understanding the evolution of granitic magma and the connection between plutonic and volcanic rocks. Crystal accumulation and melt extraction are the two key factors in the separation process. However, the existing geochemical indicators for crystal-melt separation in many granitic plutons are largely concealed by the remaining interstitial melt. Here, we report

The oxidation state of iron in mantle-derived melts is commonly used to determine the oxygen fugacity (fO2) of magmas and their related sources. The accurate and precise determination of the iron oxidation state ratio of Mid-Oceanic Ridge Basalt (MORB) glasses has been a matter of controversy for the last three decades. None of the wet chemical methods used in the literature to measure this ratio converge

Accurate knowledge of the composition of Earth’s major chemical reservoirs is fundamental for constraining all modern geochemical cycles. Basaltic rocks provide a direct way of sampling the composition of Earth’s inaccessible interior. Here, we present the first comprehensive neodymium (Nd) stable isotope analyses for a global compilation of mid-ocean ridge, ocean island, continental intraplate and

Water is key to many geodynamical processes in the Earth's upper mantle, yet its preservation in mantle minerals is still debated. To throw some light on this problem, we here carried out an integrated study of whole-rock and mineral chemistry, and hydrogen concentrations in olivine, orthopyroxene, and clinopyroxene within 18 spinel lherzolite samples from three localities (Lianshan, Panshishan, and

Mid-ocean ridge (MOR) hydrothermal vent fluids are enriched with dissolved barium, but due to barite (BaSO4) precipitation during mixing between Ba-bearing vent fluids and SO4-bearing seawater, the magnitude of hydrothermal Ba input to the ocean remains uncertain. Deep-ocean Ba isotopes show evidence for non-conservative behavior, which might be explained by input of isotopically heavy hydrothermal

The magnitude of temperature changes in the Early Jurassic are not well known. Clumped isotope measurements can potentially be used to provide better constrains, but unfortunately many of the well-studied sedimentary successions that preserve Lower Jurassic fossils experienced burial temperatures above the limits of preservation of Δ47, which for geological timescales is thought to be between 80-120°C

Magma-carbonate interaction and recycled oceanic crust in the mantle source are thought to have played a critical role in the genesis of magmatic Fe-Ti-V oxide ore deposits in the Emeishan mantle plume-related large igneous province in southwestern China. To test these hypotheses, we have carried out a combined study of zircon Hf-O isotopes and whole-rock Sr-Nd isotopes on three representative magmatic

The formation of H2CO3 and HCO3− from CO2 is common in aqueous environmental systems and occurs via the CO2 hydration and hydroxylation reactions. The reactions are especially important in the context of CaCO3 mineral precipitation. The reactions carry with them equilibrium and kinetic isotope fractionations that impact paleoclimate proxy records. Herein, quantum mechanical calculations of dissolved

Magnesium (Mg) isotopes fractionate during rock/mineral weathering and leaching, secondary mineral neoformation, adsorption/desorption, and plant-related Mg recycling, but the mechanisms and extent of fractionation are not well understood. Here, we report the fate of Mg and its isotopes during basalt weathering and soil development in the Hawaiian Islands by sampling soils of varying age (0.3, 20,

Fe(II) oxidation by O2 is an important process generating Fe (oxyhydr)oxides, which play sorptive, structural and electron-transfer roles in soils. Here we explored how native minerals and organic matter (OM) affect the rate of Fe(II) oxidation and resulting de novo Fe(III) minerals in soil slurries. A topsoil was collected from Luquillo tropical forest, and a topsoil and subsoil were collected from

Located in a closed basin in the McMurdo Dry Valleys, East Antarctica, Lake Vida brine is a cold (-13°C), hypersaline, interstitial, anoxic, and aphotic ecosystem trapped within 27+ m of ice. This brine is not in contact with the atmosphere, and currently hosts a slow-growing, cold-limited bacteria-dominated ecosystem that have persisted for at least ∼2800 years. Analysis of the dichloromethane extractable

Iron formations (IFs) are iron-rich chemical sediments that were widespread throughout the Precambrian. The deposition of IFs has provided key evidence about the prevalence of anoxic and ferruginous marine conditions throughout Earth’s history. Here, we describe the Shikebutai IF, hosted in a Late Carboniferous volcano-sedimentary sequence in the Western Tianshan region of northwest China. The IF is

We investigated the speciation of Fe and distributions of Fe-binding ligands in the hydrothermal plumes over high- and low-temperature vents and over diffuse venting fields above the Mariana back-arc spreading center. The concentrations of ligands ([L]) and conditional stability constants (K’FeL) of the natural Fe ligand pool were measured by a reverse titration-competitive ligand exchange-adsorption

Barium isotopes could be a novel tracer in low-temperature geochemical processes such as the Ba cycle in rivers and oceans. Equilibrium Ba isotope fractionation between Ba-hosting minerals and aqueous solution is of great importance for the applications of Ba isotopes in geochemistry, but it remains poorly constrained. In this study, we performed first-principles calculations based on the density functional

Coccolithophores are a group of phytoplankton widely distributed in the ocean, which secrete extracellular calcite plates termed coccoliths. Coccoliths have been increasingly employed as an archive for geochemical, ecological and paleoclimate studies in recent years. A robust application of coccolith-based geochemical proxies relies on understanding the carbon acquisition strategies and the pathways

Magnesium stable isotope ratios and minor element abundances of five olivine particles from comet 81P/Wild 2 were examined by secondary ion mass spectrometry (SIMS). Wild 2 olivine particles exhibit only small variations in δ25MgDSM-3 values from –1.0 +0.4/–0.5 ‰ to 0.6 +0.5/–0.6 ‰ (2σ). This variation can be simply explained by mass-dependent fractionation from Mg isotopic compositions of the Earth

The liquid metal–liquid silicate partitioning of molybdenum and tungsten during core formation must be well-constrained in order to understand the evolution of Earth and other planetary bodies, in particular because the Hf–W isotopic system is used to date early planetary evolution. The partition coefficients DMo and DW have been suggested to depend on pressure, temperature, silicate and metal compositions

Deep-rooted mantle plumes provide a link for carbon between Earth’s interior and its surface. Low-degree partial melting of CO2-bearing mantle is predicted to produce carbonated melts in the deep mantle, but carbonated melts are rarely found in modern oceanic settings, and the role of primary carbonated silicate melts in mantle-plume volcanism remains unclear. Because low-degree mantle melting tends

Lithological heterogeneity is a widely accepted feature of the Earth’s mantle, with recycled crustal material accounting for a significant part of heterogeneity in ocean island basalt (OIB) geochemistry. Fe isotopes have been used to link geochemical heterogeneity in OIB sources to distinct mantle lithologies due to their mineral-specific equilibrium fractionation effects, or their composition, such

Ages determined for magnesian and ferroan anorthosite crustal rock suites overlap, suggesting they formed contemporaneously about 4.3–4.5 Ga. A notable exception is the Sm-Nd age previously determined on Mg-suite gabbronorite 67667 which is at least 100 Ma younger than the youngest ferroan anorthosite. New chronologic measurements of 67667 presented here yield concordant Sm-Nd and Rb-Sr mineral isochron

Ordinary chondrites (OCs) are variably thermally metamorphosed meteorites thought to originate from at least three different parent bodies (H, L, and LL) in the Main Belt of asteroids. The thermal evolutions of OC parent bodies are frequently explained by the onion shell model; however, a competing hypothesis is the fragmentation-reassembly model. The onion shell model proposes undisrupted, internally

Using kinetic Monte Carlo simulations and scaling approaches, we describe the far from equilibrium calcite dissolution in neutral to alkaline solution and in scales ranging from the molecule detachment from surfaces to that of crystalline grains. The parameters of the thermally activated model are calibrated by the velocities of terrace steps and densities of monolayer pits measured in atomic force

Chromium stable isotope ratios are used to trace the reduction of Cr(VI) to Cr(III) in both ancient and modern systems. However, quantitative interpretation of Cr isotopic signatures has been stymied by the large variability in isotopic fractionation factors for Cr(VI) reduction by different reductants. Here we determine Cr isotope fractionation factors during Cr(VI) reduction by Fe(II/III)-bearing

In this study, the effect of Ti4+ on the structure of nepheline glass (NaAlSiO4) is investigated as SiO2 is systematically replaced with TiO2. Traditionally, TiO2 is considered to be a nucleating agent for silicate crystallization but can also be incorporated into the glass network in relatively large amounts as either a network former or modifier depending on its coordination with oxygen. To determine

The solubility of calcite was measured at 100, 120, 140 and 160 °C at 1–50 bar pCO2 in 10−3–0.1 mol·kg−1 NaCl solutions using a new experimental setup involving in situ pH measurements with high-temperature solid-contact H-selective glass and two types of reference electrodes: (i) Ag/AgCl in 3.5 M KCl, saturated AgCl placed in a Teflon extensible container with liquid junction, and (ii) solid-contact

Pyrogenic organic matter (pyOM) is the solid residue left after pyrolysis of organic matter, a process occurring in nature during forest fires. Upon rain events, pyrogenic dissolved organic matter (pyDOM) leaches into the rain water and is transferred to the aquatic environment where it has been identified as an important component of the global carbon cycle. Overall, pyDOM consists of highly condensed

Amorphous calcium carbonate (ACC) has been identified or inferred to exist in many groups of marine organisms that produce biominerals widely used as geochemical archives (e.g. foraminifera, molluscs, echinoderms). However, little is known about trace element incorporation into ACC, and thus it is not understood how precipitation through an ACC precursor might impact the fidelity of climate proxies

In this study, to better understand the factors controlling the concentration and isotope composition of lithium (Li) in the ocean, we investigated the behaviour of Li during interaction of kaolinite with artificial seawater. Dissolution of kaolinite in Li-free seawater at acidic conditions (exp. 1) results in a strong preferential release of light Li isotopes, with △7Liaq-kaol ∼ -19 ‰, likely reflecting

The Earth’s mantle holds more carbon than its oceans, atmosphere and continents combined, yet the distribution of carbon within the mantle remains uncertain. Our best constraints on the distribution of carbon within the upper mantle are derived from the carbon-trace element systematics of ultra-depleted glasses and melt inclusions from mid-ocean ridge basalts. However, carbon-trace element systematics

(285 words) Conflicting results exist regarding the mechanisms, direction, and magnitude of Zr isotope fractionation in igneous systems. To better understand the origin of the fractionations observed in magmatic Zr-bearing minerals and bulk rocks, we theoretically investigated the main potential driving processes: thermodynamic equilibrium effects driven by either (i) vibrational energy or (ii) nuclear

Dissimilatory iron reduction (DIR) plays an essential role in biogeochemical Fe cycling in anoxic environments. At near-neutral pH, in both biotic and abiotic systems, aqueous Fe(II) (Fe(II)aq) interacts with reactive ferric (hydr)oxides via electron transfer and atom exchange that is catalyzed by large amounts of sorbed Fe(II). This may result in substantial Fe isotope exchange, which, at equilibrium

Intramolecular isotope distributions, including isotope clumping and position specific fractionation, can provide proxies for the formation temperature and formation and destruction pathways of molecules. In this study, we explore the position-specific hydrogen isotope distribution in propane. We analyzed propane samples from 10 different petroleum systems with high-resolution molecular mass spectrometry

Stable isotope fractionation in magmatic systems depends on equilibrium isotope fractionation between different phases. However, current equilibrium stable isotope theory mostly assumes ideal crystal structures and simple chemical compositions, but it is unclear how the pressure and complex compositional variations in natural microscopic mineral structures affect inter-mineral stable isotope fractionation

We measured oxygen isotope ratios and major elemental compositions of non-porphyritic chondrules and lithic fragments with various textures and chemical compositions in the Asuka-881020 CH chondrite. The oxygen isotope ratios plot along the primitive chondrule mineral line with Δ17O (=δ17O – 0.52 × δ18O) values from ∼−21‰ to +5‰. The Δ17O values increase with decreasing Mg# (=molar [MgO]/[MgO + FeO]%)

Submarine groundwater discharge (SGD) can be a significant source of chemical pollutants from land to ocean. Here, we first estimated SGD using radium isotopes and related nutrient fluxes at the local scale in Jiaozhou Bay (JZB), a typical Chinese system that is experiencing rapid urban and industrial development. We then summarized SGD studies off China to assess the large-scale implications of SGD

Uranium (U) isotopes can be used to estimate the comminution age of sediments, i.e. the time elapsed from sediment production on continents, via weathering and physical erosion, to deposition in the sedimentary record. The calculation of this comminution age is based on measured (234U/238U) activity ratios in river sediments, and inferred time-dependent recoil effect, which leads to the preferential

Interactions between microorganisms and clay minerals influence the transport and cycling of metal contaminants in both marine and terrestrial environments. The present study was conducted to quantify the adsorption of dissolved cadmium, Cd(II), under seawater-like conditions to the marine cyanobacterium Synechococcus sp. PCC 7002, three common clay minerals (kaolinite, montmorillonite and illite)

Recent geodynamic models and geothermometers suggest that slabs in intermediate to hot subduction zone cross the water-saturated basalt solidus, indicating that hydrous silicate melts are important agents of mass transfer from slab to mantle wedge beneath arcs. Yet the effects of basaltic crust-derived hydrous melt fluxing on mantle wedge melting are poorly known. Here we present the melting phase

Knowledge of the identity and thermodynamic properties of aqueous molybdenum (Mo) species at elevated temperatures and pressures is important for understanding the extraction of Mo from source rocks and the formation of hydrothermal deposits. Chlorine and sulfur are two major components in crustal fluids. Several studies have investigated Mo speciation and solubility in chloride-bearing hydrothermal

Clinopyroxene is a common phase in a variety of hydrothermal ore deposits, notably in skarn deposits where it typically occurs as a major constituent. It commonly displays variations in texture and composition due to changing physicochemical conditions and contains relatively high concentrations of rare earth elements (REEs), making it an important petrogenetic indicator. In this study, we integrate

The past Martian atmosphere is often compared to the Archean Earth’s as both were dominated by CO2-rich and O2-poor chemistries. Archean Earth rocks preserve mass-independently fractionated sulfur isotopes (S-MIF; non-zero Δ33S and Δ36S), originating from photochemistry in an anoxic atmosphere. Thus, Martian crustal rocks might also be expected to preserve a S-MIF signature, providing insights into

The sedimentary Mo and U isotope systems have been commonly used as novel global ocean redox tracers due to their long oceanic residence times and redox-sensitive behavior. However, local sedimentary environments and global ocean redox conditions both influence the Mo and U isotope compositions of euxinic organic-rich mudrocks (ORM). Here, we further develop the coupled use of Mo and U isotope data

Harvesting quantitative fO2 information from synchrotron μ-XANES measurements of Cr2+/ΣCr in olivine phenocrysts requires robust thermodynamic or empirical models that can accurately predict Cr2+/ΣCr in basaltic liquids as a function of fO2, temperature, and liquid chemistry. We present the results from a combined experimental-XANES study designed to illuminate how evolving liquid chemistry and decreasing

Reconstructing the timing of mountain range uplift and the evolution of high-altitude plateaus is important when attempting to understand potential feedbacks between tectonics and climate at geological timescales. This requires proxies that are able to accurately reconstruct elevation during different time periods in the past. Often, the sensitivity of climatic parameters to elevation gradients, recorded

This study reports Ca-Fe isotope compositions of mineral separates in a set of peridotite xenoliths including ten lherzolites, one harzburgite, and one wehrlite from Hainan Island, south China. Iron isotope compositions show a small variation (<0.15‰ of δ56/54Fe) among olivine (ol), orthopyroxene (opx), and clinopyroxene (cpx). Δ44/40Caopx-cpx (δ44/40Caopx-δ44/40Cacpx) show a large range from 0.00‰

A genetic link between Sb mineralization and magmatism has previously been proposed, yet little is known about the mobility of Sb during magma degassing. We have carried out a series of experiments to understand the effects of fluid composition, oxygen fugacity (fO2), pressure and temperature on the partitioning of Sb between magmatic fluids and a rhyolitic melt at crustal conditions (T = 850 °C, P = 200 MPa)

Water diffusion is an important mechanism affecting magmatic water content, vapor bubble growth, and the dynamics of volcanic eruptions. Water diffusivity in silicate melts is dependent on temperature, pressure, H2O content and speciation, and melt composition. While a general model has recently been developed for water diffusivity in calc-alkaline (subalkaline) melts as a function of silica content

Diffusional isotope fractionation occurs in geochemical processes (such as magma mixing, bubble growth, and crystal growth), even at magmatic temperatures. Isotopic mass dependence of diffusion is commonly expressed as DiDj=mjmiβ, where Di and Dj are diffusion coefficients of two isotopes whose masses are mi and mj. How the dimensionless empirical parameter β depends on temperature, pressure, and composition

Rare Metal Granites (RMGs) are highly evolved intrusions with specific geochemical signatures that are the result of combined magmatic and hydrothermal processes. In most examples, the early evolution is overprinted by late subsolidus transformations and the role of magmatic and magmatic-hydrothermal fractionation processes remains unclear. The origin of fluids involved in magmatic-hydrothermal systems

The stable oxygen isotope fractionation factor between water and the aqueous hydroxide ion is a fundamental geochemical parameter widely used in the Earth Sciences and other fields. Studies from the 1960s reported α(H2O(l)-OH-(aq)), the fractionation factor between liquid H2O and aqueous OH−, theoretically as 1.046 and ∼1.048 (46‰ and 48‰ at 15 °C and 25 °C) and experimentally as 1.045 (45‰) at 15 °C

Molecular dynamics simulations are carried out on polycystalline periclase (MgO) to determine the structure and diffusivity at grain boundaries for pressures and temperatures relevant to Earth’s mantle. As temperature increases, the grain boundary structure becomes more disordered, with more ions having incomplete coordination and the system occupying regions of the energy landscape with shallower

It is widely believed that the precursors of coarse-grained CAIs in chondrites are solar nebula condensates that were later reheated and melted to a high degree. Such melting under low-pressure conditions is expected to result in evaporation of moderately volatile magnesium and silicon and their mass-dependent isotopic fractionation. The evaporation of silicate melts has been extensively studied in

Melt inclusions in zircon represent time capsules, which provide deep insights into igneous rock formation including timing, physicochemical conditions, and the compositional evolution of cogenetic magmas with respect to major, trace, and volatile elements. However, their full potential as petrogenetic indicators, in particular their usability and consistency as geothermometers, is poorly investigated