Baddeleyite (monoclinic zirconia; m-ZrO2) occurs as a late-stage accessory mineral in shergottites and has been used to determine U–Pb igneous crystallization ages via in-situ secondary ion mass spectrometry (SIMS). During shergottite ejection from the surface of Mars, baddeleyite develops a range of microstructures primarily due to a series of shock-induced transformations to high pressure and temperature

Understanding the effects of water on the geochemical behavior of carbonate melts in the Earth's interior requires thorough knowledge of their speciation and dynamical properties. However, the mechanisms of water dissolution in carbonate melts are unknown due to experimental challenges. Here we used ab-initio molecular dynamics simulations as a complementary approach to study the speciation and element

The role of metasomatized mantle in the genesis of magmatic Ni–Cu sulfide deposits in orogenic belts remains vigorously debated. The greatest challenge in clarifying uncertainties is how to track the behavior of metals during metasomatic processes in the mantle. Copper isotopes can shed new light on this enigmatic topic as the transfer of Cu during metasomatic processes can significantly fractionate

Dendritic network models have proven valuable in predicting variation in strontium concentrations [Sr] and isotope ratios (87Sr/86Sr) across large river systems. These models also support inference about sources and processes controlling Sr fluxes from such systems, although this capacity has not been exploited in previous work. Here, we apply these methods to model [Sr] and 87Sr/86Sr values of a large

Human activity and climate change are altering natural rates and intensities of wildfire, but the scale and extent of burning prior to the modern era are poorly understood. Paleofire activity may be reconstructed using a variety of records (e.g., charcoal in lake sediments, burn scars on tree rings), but these are not available in all environmental settings. Here we investigate the utility of a novel

The Altiplano-Puna Plateau of the Central Andes hosts numerous lakes, playa-lakes, and salars with a great diversity and abundance of carbonates forming under extreme climatic, hydrologic, and environmental conditions. To unravel the underlying processes controlling the formation of carbonates and their geochemical signatures in hypersaline systems, we investigated coupled brine-carbonate samples in

The uranium isotope composition (δ238U) of seawater is a powerful proxy for the extent of marine anoxia. For paleoredox reconstructions, carbonates are the most popular U isotope archive, but they have recently come under increased scrutiny as their δ238U values are subject to diagenetic alteration after deposition. Therefore, there is a need to investigate other archives that may record and preserve

In recent years, numerous geodynamic studies have concentrated on serpentinites and the serpentinization processes that occur within subduction zones. However, as an important host phase for Mg, whether Mg isotopic fractionation occurs during peridotite serpentinization is still unclear. In our study, we conducted high-precision Mg isotope analyses on serpentinized peridotites and forearc serpentinites

Chemical erosion in river basins influence the climate by both consuming (via silicate erosion and carbon burial) and releasing (via H2SO4-mediated carbonate weathering and organic oxidation) atmospheric CO2. Net erosional effect of a basin on carbon cycle, therefore, requires precise rate assessment of all these pathways; combined data for the four processes for a given basin are sparse. In this contribution

Zirconium (Zr) stable isotope variations occur among co-existing Zr-rich accessory phases as well as at the bulk-rock scale, but the petrologic mechanism(s) responsible for Zr isotope fractionation during magmatic differentiation remain unclear. Juvenile magma generation and intra-crustal differentiation in convergent continental margins may play a crucial role in developing Zr isotope variations,

Large Ca isotope variations recorded in mantle xenoliths and mantle-derived igneous rocks have been widely used to decode the origin of mantle heterogeneity, especially to trace recycled sedimentary carbonates. However, it is still unclear whether and how the subduction of sedimentary carbonate causes significant Ca isotope fractionation in the mantle in correspondence of convergent margins. In this

Steranes and hopanes are the biomarkers of eukaryotic sterols and bacterial hopanols. Extracted from sedimentary rock, they are widely used to assess burial temperatures and palaeoecological conditions. The relative proportion of steranes and hopanes is commonly applied as a measure of the flux of eukaryotic versus bacterial biomass into sediments, and the relative abundances of C27, C28 and C29 steranes

We present the first in-situ partitioning data for bromine between a natural basaltic melt and a coexisting fluid. For this study hydrothermal diamond anvil cell experiments at pressures up to 1.7 GPa were conducted. We combined laser heating to melt the basalt glass with external heating to lower the temperature gradient in the cell and to initiate circulation for the aqueous fluid. Bromine concentrations

Several mechanisms could produce the biorelevant organic compounds contained in carbonaceous meteorites. The ratio of heavy-to-light stable isotopes can constrain a compound's formation history because substrates, mechanisms, and physiochemical conditions impact isotope ratios of a reaction's products. Prior stable isotope studies of meteoritic organic compounds have interpreted data via qualitative

Trace element diffusion is a powerful tracer of kinetic magmatic processes such as recharge and fluid exsolution. However, the dependence of diffusivities (D) on melt water contents is poorly quantified, and most trace element diffusivities were determined in water-free melts unrealistic for most natural magmatic systems. Here, we investigate the diffusion of the alkali trace elements Li, Rb, and Cs

Metasomatism of the sub-continental lithospheric mantle (SCLM) can result in enrichment in volatile elements introduced via subduction of seawater-altered oceanic lithosphere. Subduction-related metasomatism can introduce chlorine isotope heterogeneity to the SCLM inherited from the subducted source, which can be used to characterize the source of metasomatism. This study presents Cl isotope compositions

Triple oxygen isotope ratios (17O/16O, 18O/16O) of bioapatite (apatite, carbonate) of mammals can be used for paleo-CO2 reconstruction, as climate proxies, and for physiological studies. Key to this approach is that mammals incorporate atmospheric molecular oxygen with a marked 17O anomaly. Here, we report new apatite tooth enamel triple oxygen isotope data of a large set of terrestrial mammals (0

The sulfur content at sulfide saturation (SCSS) of a silicate melt can regulate the stability of sulfides and, therefore, chalcophile elements’ behaviors in planetary magma oceans. Many studies have reported high-pressure experiments to determine SCSS using either linear or exponential regressions to parameterize the thermodynamics of the system. Although these empirical equations describe the effects

Quantitative knowledge of inter-mineral and mineral–melt isotopic fractionation factors is of crucial importance to interpret variability of mass-dependent isotope ratios in terrestrial rocks and meteorites. The isotopic composition of Ni shows great promise as a tracer of planetary differentiation, but the lack of solid constraints on the sign and magnitude of equilibrium Ni isotope fractionation

In this study, we investigate the 40Ar/39Ar systematics of nineteen diogenites thought to come from deep crustal levels of asteroid 4 Vesta. We applied both Electron Backscattered Diffraction (EBSD) and 40Ar/39Ar and methods to the unbrecciated diogenite LAP 031381. We obtained three plateau ages resulting in a combined weighted mean age of 4441 ± 15 Ma (P = 0.16). The EBSD analyses suggest that LAP

Host to some of Earth's earliest evidence of life, the fossiliferous lowermost chert-barite sequence (DFc1) in the ~3.5 Ga Dresser Formation of the Pilbara Craton, Western Australia is interpreted to have deposited within a dynamic volcanic-hydrothermal caldera. To date, three end-member fluid compositions (marine, hydrothermal, and subaerial) have been identified using trace and rare earth elements

The purpose of this work is to test the ability of laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) to provide absolute ages of useful precision on calcitic fossils. Data on the belemnite Belemnitella americana, from the Peedee Formation (North Carolina, USA) define an isochron with a Campanian/Maastrichtian age of 72 ± 2 Ma. Two other specimens from the same area show highly

The mechanisms of in vacuo release of Ar are investigated by bringing them into context with nine other rare gas isotopes and by studying the mineralogical modifications that occur in their host mineral. A 200 mg shard of Durango fluorapatite was step-heated after neutron irradiation. It contained radiogenic 4He from natural U decay and artificially produced major rare gas isotopes: 20Ne from F, 37Ar

The Late Cretaceous–early Paleogene interval is globally associated with transient to long-term changes in the stable carbon isotopic composition of marine carbonates (δ13Ccarb). Based on biostratigraphic reconstruction, this critical period of Earth's history is thought to coincide with the deposition of world heritage Paleocene phosphate deposits (phosphorites) in northwestern Morocco. However, the

Crustal recycling can induce significant chemical and lithological heterogeneity of the mantle. Ocean island basalts (OIBs) are the surface expressions of rising mantle plumes from the Earth's deep interior and thus can be a probe of the compositional heterogeneity in the deep mantle. Endmember OIBs sampled the most isotopically extreme mantle components including EM1 (Enriched mantle 1), EM2 (Enriched

The Okinawa Trough is a sediment-covered intra-continental back-arc basin with active hydrothermal activities. The sulfur isotopic systematics of the hydrothermal systems in the Okinawa Trough remain unclear owing to the complex sulfur reservoirs. To address these uncertainties, we conducted in situ S isotopic combined with whole-rock geochemical, Pb isotopic, and barite Sr isotopic analyses of typical

The development of LA-ICP-MS and other microanalytical techniques for in situ analysis of single fluid inclusions has made it possible to quantify the elemental concentration of major elements, trace metals, sulfur and halogens in fluid inclusions from a wide range of geological environments. The established quantification methods typically interpret the LA-ICP-MS and microthermometric data (melting

The Capitanian mass extinction was a severe biotic crisis in geological history. To present more evidence for this event, this study acquired geochemical data from shelf-margin facies deposits in the Upper Yangtze region, China (i.e., the Shangsi section; the third member of the Maokou Formation [Mao III Member] prior to the Capitanian mass extinction). A significant Hg anomaly is associated with the

Evaluating the stratigraphy of the North Pacific is the first step towards understanding the role of this region in climate variability in the past. This region has been notoriously difficult to work in due to the presumed low sedimentation rates (<0.1 cm/kyr), which would likely be inadequate to capture glacial-interglacial cycles of the Late Pleistocene (∼500,000 years). These low sedimentation rates

Cave carbonates are an important archive of terrestrial paleoclimate and have previously been analyzed using multiple proxies. A few studies have explored the potential for carbonate clumped isotope thermometry as a tool for constraining past temperatures. To date, most papers utilizing this method have focused on mass-47 clumped isotope values (Δ47) at a single location and reported that cave carbonate

A common technique for determining the mass accumulation rates of marine sediments is through measurements of constant flux proxies. These proxies, like unsupported 230Th and extraterrestrial 3He, are buried at a known rate at the seafloor, and thus their concentration in sediments is inversely proportional to the vertical mass accumulation rate of ambient sediments. These two proxies have varied assumptions

The Macusani Volcanics and related rocks (SE Peru) are well known examples of erupted strongly peraluminous rare-metal rich silicic magmas. We used the phenocryst/matrix glass method to determine relevant mineral/melt partition coefficients to facilitate modeling of such systems. Concentrations of trace (Li, Be, B, Al, P, Ti, Mn, Zn, Ge, Rb, Sr, Zr, Nb, Sn, Cs, Ba, La, Sm, Eu, Gd, Yb, Ta, W, Pb and

Deep ultraviolet Raman spectroscopy is an essential component of the Perseverance rover operating on Mars. Here we propose a proof of concept of deep-UV Raman structural characterization of volcanologically relevant silicate glasses to provide a suitable analytical method of UV Raman spectra collected on Mars. The results show few but substantial spectral differences concerning those obtained by conventional

Highly alkaline (pH 9–12) waters can arise from a range of globally significant and environmentally impactful industrial processes such as lime, steel and cement production, alumina refining and energy generation (e.g. combustion ashes). Such residue storage sites are often characterized by extreme geochemical conditions that can be hazardous to aquatic life but are quickly becoming a critical focus

We present the first volatile contents (H2O, CO2, Cl, F, S) of young (< 6 Ma) submarine basaltic glasses from the Phoenix and West Scotia mid-ocean ridges and the Bransfield Strait back-arc of the South Shetland subduction zone in the Antarctic Peninsula. The volatile contents of the MORB glasses correspond well with those of published Pacific MORB and reflect covariations in source enrichment and

Zirconium (Zr) stable isotopes recently emerged as potential tracers of magmatic processes and, as a result, their behavior in high-temperature environments have been the focus of extensive characterization. In contrast, few studies have focused on Zr behavior and isotopic fractionation in low temperature or aqueous environments. Here, we describe a new analytical routine for highly precise and accurate

Angrites are a small group of basaltic meteorites and their origin is currently disputed. Among these, Northwest Africa (NWA) 12774 is a quenched angrite that was reported having an anomalously high bulk Cr2O3 content (∼0.45 wt%). However, the reason behind this anomaly, which is critical for understanding the evolution of the angrite parent body, remains unknown. Here, we performed a detailed petrographic

Titanium occurs as Ti3+, in addition to the more usual Ti4+, in extraterrestrial materials such as Lunar basalts and chondritic meteorites. The proportion of Ti as Ti3+ was investigated by Ti K-edge X-ray absorption near edge structure (XANES) spectroscopy for five silicate glass compositions quenched from melts equilibrated at 1400°C, atmospheric pressure, and oxygen fugacities (fO2) in log units

Polytungstates have toxicity, mobility, and bioavailability quite different from those of monomeric tungstates, the most common tungsten (W) species. To date, relevant studies of polytungstates have been conducted under laboratory conditions, and there is a lack of studies on such W species in natural waters. In the present study, polytungstates at environmentally relevant concentrations were detected

Peridotites in the Yarlung Zangbo ophiolite (YZO) have the potential to elaborate the mantle dynamics that operated below the Neo-Tethyan oceanic crust. Here, we measured major and trace element concentrations of minerals (e.g., clinopyroxene, orthopyroxene, olivine, and spinel) in YZO harzburgites and lherzolites to trace the origin and evolution of the YZO. The rare earth element (REE) patterns of

The geochemical characteristics of nascent oceanic crust play a crucial role in unraveling the mantle dynamics of the initial opening of an ocean. The Gulf of California, located at the East Pacific margin, is one of the best examples of an active and obliquely rifted continental margin. However, the mantle source composition of the nascent oceanic crust in the central part of the Gulf has not yet

In this study, we developed an ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS) approach to measure the concentration of total reactive thiol binding sites in a range of types of environmental samples by monitoring the decrease of monobromo-(trimethylammonio)-bimane (qBBr) caused by thiol-qBBr binding reactions. We first examined the stability of qBBr and potential side reactions

Proteins are the most stable of the macromolecules that carry genetic information over long periods of time. Closed systems are more likely to retain endogenous proteins or their degradation products. Amino acid racemisation data in experimental and subfossil material suggests that mollusc shell and avian eggshell calcite crystals can demonstrate closed system behaviour, retaining endogenous amino

The quantification of anaerobic oxidation of organic matter in the global seabed is to a large extent based on transport-reaction modeling of pore water ions involved in the mineralization processes. As the predominant of these processes, sulfate reduction can be modeled from the depth distribution of sulfate and other relevant solutes. An active organoclastic sulfate reduction is typically characterized

Ophiolitic mantle rocks play a crucial role in understanding deep geochemical cycling and the transfer of components associated with slab-mantle interactions. Geochemical and geochronological and geochemical analysis of zircon and TiO2 polymorphs (e.g., rutile) present within mantle rocks of the Eocene New Caledonian ophiolite reveal discrete magmatic and xenocrystic populations amongst harzburgite

Partial melting of mantle peridotite from which considerable amounts of melt have been extracted during prior melting episodes generates melts characterized by low incompatible element contents and very low ratios of highly to moderately incompatible elements, so-called ‘ultra-depleted’ melts. Reaction of peridotite with percolating ultra-depleted melts has been inferred from petrological-geochemical

Ferromagnesian chondrules present a remarkable dichotomy between reduced (type I) and oxidized (type II) varieties. How these formed, and how they may be related remains contentious. Many type II chondrules, especially in carbonaceous chondrites, contain forsteritic grains in disequilibrium with FeO-rich host olivine grains, which must be relicts of precursor material. In this study, we analyzed the

The balance between alkalinity generation by carbonate and silicate weathering and sulfuric acid generation by sulfide weathering controls the effect of weathering on atmospheric pCO2 over geologic timescales. How this balance varies across environmental gradients remains poorly constrained. Here, we analyze this balance across an erosional gradient of two orders of magnitude in the Three Rivers (Yangtze