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The Stacey-Davis formulation (Stacey and Davis, 2004) for determining the Gruneisen parameter γ and its volume derivatives for the Earth outer core has been improved by using the revised values of λ 0 and λ ∞ , the third order Gruneisen parameter at zero-pressure and infinite pressure, respectively. These values of λ 0 and λ ∞ are consistent with the Stacey reciprocal K-primed equation of state. The results for gamma and its volume derivatives obtained from the Stacey-Davis formulation are compared with those calculated from the Shanker reciprocal gamma equation (Shanker et al., 2017). The parameter λ ∞ used in the present study satisfies the thermodynamic constraint found by Stacey and Hodgkinson (2019) according to which λ ∞ must be less than K ∞ ′ .

Mineral replacement reactions are one of the most important phenomena controlling the geochemical cycle of elements on Earth. In the early years, solid-state diffusion was proposed as the main mechanism for mineral replacement reactions, but over the past 20 years the importance of the coupled dissolution-reprecipitation (CDR) mechanism has been recognized. In the presence of a fluid phase and at low temperatures (e.g.

The evolution of the U-Pb decay system is determined by their initial isotopic composition in the proto-Earth and the subsequent global differentiation. The differentiation is highly complicated because of large-scale evaporation and multi-stage core formation in Earth accretion. We statistically rebuild the accretional history of Earth using a series of N-body simulations. This provides us with an estimation of the amount of silicate melting and thus temperature and pressure at the bottom of the magma oceans driven by continuous planetesimal impacts. We further assumed different evolutionary paths of the redox state and found a reduced process from an oxidized state consistent with the current value of Pb content and μ value (238U/204Pb) in the bulk silicate Earth. Meanwhile, the fraction of the impactor's core that participates in the re-equilibration is around 0.2–0.7. Our model predicts the final μ value equals the observed value, 8.25, regardless of the minor contribution of the late veneer (0.2). The evolution of μ determines the growth rate of radiogenic Pb isotopes. The episodic increase of μ in multi-stage core formation accelerates the growth of radiogenic Pb isotopes (206Pb and 207Pb) and finally causes a slight deviation of the composition of Pb isotopes (206Pb/204Pb and 207Pb/204Pb) to the right of 4.567-Ga Earth Geochron. A multi-stage evolution model for U–Pb system can explain the modern terrestrial μ value, but has little influence on the puzzle of “the first Pb paradox”.

Olivine is one of the most widespread minerals of the Earth's upper mantle. It is widely accepted in the scientific community, that during olivine interaction with water large amounts of hydrogen are released. On the other hand, the idea of an accumulation of huge hydrogen amounts in the core and lower mantle of the Earth is becoming more and more popular now. In this paper, we attempt to assess the possible interaction of hydrogen rising from the depths with olivine in the upper mantle, which has not been done before. Program GEMS was used for modeling calculations. The influence of the hydrogen amount on the serpentinization process at T = 323.15 ÷ 593.15 K and P = 3⋅107 ÷ 3⋅108 Pa has been estimated. The initial composition of the system was set as 1 mol of olivine (Fe0.1Mg0.9SiO4). The amount of added hydrogen was set as 1, 500, and 5000 mol. The water was not specified as a composition of the initial system. The simulation showed that hydrogen can cause the serpentinization process, which indicates in favor of the hypothesis about deep hydrogen sources, although it is not 100% proof of this.

Late accretion occurred through addition of massive impactors to Earth, leading to potential heterogeneity in the distribution of highly siderophile elements (HSE: Os, Ir, Ru, Pt, Pd, Re) within the mantle. Abyssal peridotites sample the present-day convecting mantle, which make them useful for examining the distribution of the HSE within the mantle. Here we report new HSE abundance data and 187Os/188Os ratios, in conjunction with mineral chemistry and bulk rock major- and trace-element compositions for abyssal peridotites from the fast-spreading Pacific Antarctic Ridge (PAR) and East Pacific Rise (Hess Deep), and for slow to intermediate spreading ridges from the Southwest Indian Ridge, Central Indian Ridge and Mid-Atlantic Ridge. These analyses expand the global abyssal peridotite Os isotope and HSE database, enabling evaluation of potential variations with spreading rate, from ultraslow ( 2 wt.%, the average composition of the primitive mantle is 0.3 ppb Re, 4.9 ppb Pd, 7.1 ppb Pt, 7.2 ppb Ru, 3.8 ppb Ir and Os, showing no Pd/Ir, but a positive Ru/Ir anomaly, relative to chondrites. There is ∼50% variation of the HSE abundances in the oceanic mantle, with much of this variation being observed at small length scales (

Basalts, which cover about 70% of the Earth's surface, are igneous rocks originating from cooling and solidifying the magma on the Earth's surface. Products obtained from the melting of rocks have a wide market and can be considered the precursors of glass-ceramic technology. These materials are promising due to the possibility of converting low-cost natural raw materials into products with excellent mechanical, thermal, and chemical properties. In this article, a general overview of the basic principles for obtaining basaltic glass-ceramic materials will be made, as well as their properties, applications, and potentialities.

In the present study Sugarcane bagasse ash has been used to stabilize the OPC cement and Wheat straws are used as a reinforcement. The attempt has been made to understand the change in the properties of the casted CEB compared to conventional ones. Thereafter, the cost consideration has also been taken in to count to define the better product. Present work support the use of SBA and WS for compressed earth blocks. Simultaneously, study also propose the future scope to determine the durability of the casted product as, both SBA and WS are Bio-degradable materials. However, both SBA and WS are agricultural waste and their disposal as a utilization for strength of earth block is a step towards green development.

Surface modification of different functional molecules onto NaREF4 (RE = rare earth) upconversion nanoparticles (UCNPs) impart their multiple functionalities. Functional molecules can be loaded onto NaREF4 UCNPs through the formation of coordination bonds between the surface-exposed RE3+ ions and the appropriate chemical groups of functional molecules. The density of surface RE3+ ions directly determines the loading efficiency of NaREF4 UCNPs. However, NaREF4 is a binary cation system, rendering the surface-distributed Na+ and RE3+ ions remains a mystery. Here, we develop an effective strategy to significantly enhance the density of surface RE3+ ions, thus maximizing the loading capacity of NaREF4 UCNPs. This strategy is based on a heterovalent cation exchange (HCE) reaction in the surface region in which Na+ ions are replaced by RE3+ ions. The density of surface ligands enhances from 3.6 to 8.8 molecules/nm2 after reaction, suggesting that the loading efficiency increases by approximately 150%. Benefiting from the improved loading capacity, we demonstrate such surface-RE-rich nanoparticles have the ability to offer higher colloidal stability and more desirable photodynamic therapy (PDT) efficacy. This work not only advances our understanding of cation exchange reactions in RE-based nanoparticles, but also provides significant value for considerable applications such as sensing, bioimaging, and therapy.

As part of the space experiment “Test”, a roll of cotton cloth fixed on the outer surface of the International Space Station for more than 10 years was delivered to the Earth in September 2019. The elemental composition of two fragments of the cloth, contaminated and clean, was determined using instrumental neutron activation analysis at the IBR-2 reactor. Along with 19 elements (Mg, Al, Cl, Ca, Ti, Cr, Mn, Fe, Co, Ni, Zn, Rb, Sr, Ag, Sb, Ba, Sm) determined on both fragments of the cloth, additional 20 elements (Na, Si, Sc, Cu, As, Se, Br, Mo, Zr, Cd, I, La, Ce, Eu, Ta, W, Re, Ir, Th, and U) were determined only on the contaminated fragment. The morphology of the rolled cotton cloth was characterized using Scanning Electron Microscopy. Gama and liquid beta spectroscopy were applied to measure the radioactivity of the cloth fragments. Possible sources of the determined chemical elements deposited on the cloth were discussed.

Feldspars are the most abundant minerals in the Earth’s crust, and are also important constituents of many lunar rocks and some stony meteorites. Albite (NaAlSi3O8) makes up the sodium corner of the feldspar ternary diagram (KAlSi3O8 - NaAlSi3O8 – CaAl2Si2O8) and connects the alkali-feldspar and plagioclase binary joins. Synthesis of albite, however, has long been a problem, even at high temperatures and even at high pressures when dry. In fact, most successful syntheses require the combination of high-pressure, high-temperature, and hydrothermal environments. This paper presents a sol–gel method of albite synthesis that requires hydrothermal processing followed by high-temperature recrystallization, but no high-pressure environments. This has the advantage of allowing synthesis of relatively large amounts of material and controlled elemental substitutions.

The energy conversion in Earth’s surface environments over geological history heavily involves the redox reactions of natural minerals. Natural Mn(III/IV) oxides and Mn2+(aq) is one of the most important redox couples that significantly dictate the electron flow in nature. Elucidating their formation and redox reactions is of critical importance for understanding numerous elemental cycles and the evolution of redox environments on Earth and other planets. Previous studies generally consider biotic processes as the dominant oxidation pathway for Mn2+(aq) in natural environments. In this study, we demonstrate rapid abiotic oxidation of Mn2+(aq) through photocatalytic reactions in the presence of natural Fe oxide minerals at rates comparable to those of currently known biotic/abiotic oxidation processes. Fe oxide minerals not only facilitate the electron transfer, but also serve as templates for the heterogeneous nucleation of tunnel structured Mn oxides. This finding highlights an important yet previously overlooked abiotic process on the formation of Mn oxides, which offers a new pathway for explaining the commonly observed co-occurrence of Fe and Mn oxide minerals in nature and the origin of diverse structures of Mn oxides.

Natural perchlorate (ClO4−) exists in many places on Earth, in lunar regolith, meteorites, and on the surface of Mars. Terrestrial natural ClO4− has widely variable Cl and O stable isotopic compositions (δ37Cl, δ18O, Δ17O). The δ18O and Δ17O values of ClO4− from the most hyper-arid locations co-vary. ClO4− from less arid areas has relatively little 17O excess and poor Δ17O-δ18O correlation. ClO4− from the Atacama Desert has unusually low δ37Cl (

Despite its status as a critical metal in the EU and the U.S., the geochemical behavior of gallium (Ga) in the Earth’s surface environment is not yet well constrained, which is in marked contrast to its geochemical partner aluminum (Al). Especially hydrogenetic ferromanganese crusts which may represent a potential future unconventional resource of critical metals, are surprisingly underexplored with regard to their Ga-Al systematics. This study presents the first data on the Ga-Al pair in hydrogenetic Fe-Mn crusts from various locations in the Pacific Ocean and from the Rio Grande Rise in the SW Atlantic. We also provide Ga-Al data for certified reference materials for Fe-Mn nodules NOD-P-1, NOD-A-1, and JMn-1. Our results also show that marine hydrogenetic Fe-Mn crusts cannot be considered an unconventional Ga resource, in marked contrast to several other critical metals. Aluminum and Ga concentrations in these precipitates are not controlled by detrital components. Both elements show a geochemical behavior comparable to that of the hydroxide-dominated elements Zr and Hf during scavenging from ambient seawater by hydrogenetic Fe-Mn crusts. The Ga/Al mass ratios of Atlantic (0.10–0.16 g/kg) and Pacific crusts (0.18–1.2 g/kg) are about one and a half orders of magnitude lower than those of respective ambient seawater and mimic the inter-oceanic fractionation of the Ga-Al pair between these two ocean basins. Without exception, the Atlantic Fe-Mn crusts show lower Ga/Al ratios than the Pacific crusts. The systematically lower Ga/Al ratios of the crusts relative to those of seawater reveal preferential scavenging of Al relative to Ga during the formation of Fe-Mn crusts. This is in line with previous studies that reported a higher particle reactivity of Al compared to Ga in the marine environment. However, this fractionation trend contradicts predictions based on a simplified model commonly used to approximate trace element scavenging by marine metal (hydr)oxides based on hydrolysis constants, which favors Ga enrichment relative to Al as the hydrolysis constant of Ga is higher than that of Al. The observed Ga-Al fractionation may be related to the preferential retention of Al compared to Ga on the surface of the Fe-Mn (oxyhydr)oxides because in contrast to Ga, desorption of Al is characterized by very slow reaction kinetics or is even irreversible. Alternatively, stronger organic complexation of dissolved Ga than Al in seawater (which is supported by the stability constants of various organic Ga and Al complexes) and the resulting preferential retention of Ga over Al in solution by dissolved organic ligands may be another viable mechanism to explain the observed Ga-Al fractionation between hydrogenetic Fe-Mn crusts and seawater. While more experimentally determined thermodynamic data are necessary, the rather consistent difference between hydrogenetic Fe-Mn crusts and ambient seawater supports an important role of organic ligands in the chemical speciation of Ga in seawater.

Earth canals are subjected to seepage losses during the conveyance and distribution of irrigation water. With the current conditions of climate change and water scarcity, it is becoming crucial to conserve water. Canal lining is a common solution to minimize seepage losses. In this study SEEP/W model is used to investigate the effect of compacted earth lining characteristics on seepage from trapezoidal earth canals. The amount of reduction in seepage due to lining is quantified. Different scenarios for the hydraulic conductivity, thickness, and orientation (position) of compacted earth lining are evaluated. The results show that compacted earth lining is an efficient method to reduce conveyance losses. 99.8% of the water lost by seepage can be saved if highly compacted soil is used on the bed and sides. Partial lining can also be used, the most efficient orientation of lining depends on the canal’s width. Design charts and equations are suggested.

To constrain the behavior of chalcophile (sulfide-loving) elements during arc magmatic differentiation and to understand the formation conditions of Earth’s continental crust, the partition coefficients (D) of Mn, Co, Cu, Zn, As, Se, Mo, Ag, Cd, Sn, Sb, Te, Re, Au, Pb, and Bi between monosulfide-solid-solution (MSS), Cu-rich sulfide liquid (SL; containing 11–45 wt.% Cu), and hydrous silicate melt (SM) of basaltic to dacitic compositions were determined at 1000–1200 °C, 0.5–1.0 GPa, and fO2 1–1.5 log units above the fayalite–magnetite–quartz (FMQ) buffer. The D SL / S M values are 16–160 for Co, 1100–8400 for Cu, 50–220 for Se, 1200–5900 for Ag, 50–1800 for Cd, 700–3300 for Te, 15–510 for Re, 5700–90,000 for Au, 20–440 for Pb, and 140–3300 for Bi. The D SL / S M values for Mn, Zn, As, Mo, Sn, and Sb are below 1–40. The D MSS / S M values are 55–260 for Co, 530–1700 for Cu, 74–110 for Se, 30–110 for Ag, 4–40 for Cd, 15–70 for Te, 200–5900 for Re, and 140–270 for Au. The D MSS / S M values for Mn, Zn, As, Mo, Sn, Sb, Pb, and Bi are below 1–3. The D SL / S M of Au increase with increasing Cu content of the sulfide liquid, but the D SL / S M of the other elements little affected by the Cu concentration in the sulfide liquid. Because of their distinct dissolution mechanisms in the silicate melt, the D SL / S M and D MSS / S M of Mn, Co, Zn, Cd, Sn, and Pb are mainly controlled by the silicate melt FeOtot content ([FeOtot]); the D SL / S M and D MSS / S M for Re, Mo, As, Sb, and Bi are mainly controlled by [FeOtot] and fO2; the D SL / S M and D MSS / S M for Cu, Ag, and Au are mainly controlled by [FeOtot] and the content of reduced sulfur in the silicate melt; and the D SL / S M and D MSS / S M for Se and Te are mainly controlled by fO2. Using all available D SL / S M and D MSS / S M data, a partitioning model was developed for predicting D SL / S M and D MSS / S M of chalcophile elements as a multi-function of temperature, pressure, fO2, and silicate melt and sulfide compositions. Sulfide phase relations suggest that the sulfides precipitating from arc magmas containing >100 µg/g Cu in the silicate melt occur as Cu-rich sulfide liquid, whereas the sulfides precipitating from arc magmas containing 30–70 µg/g Cu in the silicate melt occur as mixed MSS and Cu-rich sulfide liquid. Modeling the Cu evolution trends of global arc magmas illustrates that the precipitating sulfides are dominantly MSS in continental arcs with a crustal thickness of >30 km, with the proportion of sulfide liquid being less than 20%; whereas, in island arcs with a crustal thickness of

Determination of total dissolved iron (Fe) is of great significance for further studying its role in the biochemical cycle of the earth. Herein, a defective carbon black material (BPdefect) was adopted to replace metal-based composites for determination of Fe dissolved in solution via electroanalysis on modified electrode. The effects of solid loading and electrolyte on electrochemical performance were studied. The measurement accuracy of BPdefect-modified electrode was validated by determining Fe(III) standard reference materials. The BPdefect-modified electrode was also applied in Fe analysis in groundwater samples successfully.

Photo-oxidation of aqueous Fe(II) (Fe2+ and FeOH+) to Fe(III) (Fe3+) was likely involved in the formation of iron oxide deposits on early Mars and Earth. Previous studies have reported the photo-oxidation reaction rate (i.e., quantum yield, φ = the number of oxidized ferrous ions divided by the number of photons absorbed by ferrous ions) under acidic conditions (pH 0.4–3.0). However, the quantum yield has not been systematically investigated using chemical actinometry in the range of weakly acidic to neutral pH, where the photo-oxidation would have occurred on early Mars and Earth. We report quantum yields for the photo-oxidation of aqueous Fe(II) species over a pH range of 0.5–7.6 with Hg and Xe lamps (with and without optical filters) based on measured Fe(II) concentrations and photon fluxes. The quantum yield under continuous UV and visible light (>200 nm, Xe lamp) varies with pH: φ = 0.103 (±0.005) + 2.17 (±0.27) × [H+]0.5 at pH = 3.0–7.0. Our quantum yield is a few times higher than those reported by the previous studies that used a Hg lamp, indicating the wavelength dependence of the quantum yield. At higher pH (7.1–7.6), with a UV cutoff at ≤ 300 nm (filtered Xe lamp), photo-oxidation of Fe(II) is attributed to oxidation of FeOH+, with a quantum yield of 0.08 ± 0.01. Based on these quantum yields, we estimated Fe(III) (hydro)oxide precipitation rates in the early Gale lakes on Mars, and in Archean oceans on Earth. Results suggest that photo-oxidation may account for the amounts of Fe(III) (hydro)oxides in Gale sediments, assuming aqueous Fe(II) was supplied to the lakes through upwelling groundwater. Photo-oxidation of Fe(II) in Archean oceans on Earth could have been several times more intense than previously thought.

The utilization of Zhundong coal has encountered severe ash-related problems principally due to its high-alkali feature. However, the evaluation of fouling tendency and correlations of chemical properties of Zhundong coals based on a large database has been seldom performed. The present work aimed to reveal the correlations of chemical properties, distributions of alkali and alkaline earth metals (AAEMs) and iron, and the fouling propensity of Zhundong high-alkali coals based on datasets of >250 samples. The fuel ratio of the majority (∼95%) of Zhundong coals lay in the range of 1.0–2.45. A quantified correlation between fuel ratio and volatile matter content was obtained. The ash composition of Zhundong coal gathered in a small area of the ternary diagram of Fe2O3-alkali metal-alkaline earth metal oxide components. The principal sodium of water-soluble form in Zhundong coals varied notably from 45% to 95%, more than half of the potassium was insoluble form, the majority (∼90%) of alkaline earth metals were in forms of ammonium acetate-soluble and HCl-soluble, and ∼67% of iron was HCl-soluble form. The quantitative correlations based on plentiful datasets could improve the comprehension of correlations among the coal chemical properties, fouling behaviors and its reaction activity.

This work reports on the analysis of structural and spectroscopic properties of the fluoroindate glasses co-doped with Er3+/Ho3+. Structural analysis showed that erbium and holmium ions were modifier ions and depolymerizedof the fluoroindate glass network. The energy transfer processes between rare - earth ions in fluoroindate glasses pumped by and 980 nm laser diode have been also examined. Due to partial Er3+ → Ho3+ energy transfer and superposition of Er3+: 4I11/2 → 4I13/2 (2.77 μm)+ Ho3+: 5I6 → 5I7 (2.85 μm) radiative transitions in fluoroindate glass co-doped with 0.8ErF3/1.6HoF3, a broadening 3 μm luminescence (Δλ= 201 nm) was obtained. The overall energy transfer efficiency ηET1 + ηET2 was calculated to be 95% indicating efficient sensitization of the holmium ions by erbium.

Jarosite [KFe3(SO4)2(OH)6] occurs both as a hydrothermal mineral and as the product of weathering and chemical sedimentation. It has been used in 40Ar/39Ar geochronology to date water–rock interaction and weathering processes on the surfaces of Earth and Mars, but the lack of information about Ar diffusivity parameters relevant to specific types of jarosites makes the interpretation of geochronological results tentative. We have filled this gap by investigating Ar diffusion parameters in representative supergene and hypogene jarosites. Detailed diffusion studies were carried out on a hypogene jarosite sample from Gilbert, Nevada, and two supergene jarosite samples from Baiyin, China. The diffusion studies were accompanied by in-situ heating investigations in a transmission electron microscope to directly determine the thermal stability and the phase transformations that jarosite undergoes under progressive heating under ultra-high vacuum. The TEM results suggest that jarosite is stable under vacuum up to ∼400 °C, when it undergoes phase transition to yavapaiite [KFe(SO4)2] and hematite (Fe2O3). Incremental-heating experiments reveal average diffusion parameters of Ea = 138.6 ± 4.2 kJ/mol and ln(Do/a2) = 9.9 ± 0.9 ln(s−1) for hypogene jarosite; Ea = 110.3 ± 3.2 kJ/mol and ln(Do/a2) = 5.7 ± 0.7 ln(s−1) for one supergene jarosites; and Ea = 141.2 ± 7.9 kJ/mol and ln(Do/a2) = 11.3 ± 1.7 ln(s−1) for the other supergene jarosite sample from the same weathering profile. Jarosite closure temperatures depend strongly on sieve size. For samples between 500–200 µm (grain size usually used for samples in Ar geochronology), at a cooling rate 100 °C·Ma−1, the closure temperatures are 143 ± 18 °C for the hypogene jarosite, and 105 ± 8 and 113 ± 14 °C, respectively, for the two supergene jarosites. Forward modelling of incremental-heating results predicts that coarse-grained hypogene jarosite is retentive of Ar below 50 °C for 100 Ma and below 25 °C for 4 Ga. Densely packed supergene jarosite grains larger than 200 µm are suitable for 40Ar/39Ar geochronology at the timescales suitable for investigating water–rock interaction at the surface of Earth and Mars. Fine-grained, porous jarosites require detailed diffusion analyses prior to geochronology due to possible high Ar losses over Ma timescales. The absence of jarosites older than ∼40 Ma on Earth suggests that jarosite may require continuous exposure to acid oxidizing conditions, and that it does not survive burial and exhumation. Therefore, the occurrence of jarosite on Earth and Mars may identify segments of the planets’ surfaces continuously exposed to acid-oxidizing conditions since jarosite precipitation.

Fluids released within subduction zones affect many fundamental Earth processes, but very little is understood about processes of fluid transport within subduction zones and the chemistry of the fluids. Centimeter-scale variations in bulk-rock Li isotope compositions in subduction-related metamorphic rocks are observed associated with fluid-related features. The small spatial scales of these variations suggest very short duration fluid infiltration events – on the order of months to centuries. However, bulk-rock measurements record a time-integrated record, while in situ measurements in metamorphic porphyroblasts such as garnet have the potential to record individual events experienced by the rock. In this study, traverses across garnet in Franciscan eclogite and amphibolite were analyzed for Li isotopes in situ using SIMS to determine the potential for inferring the duration of metamorphic fluid flow and for deciphering fluid chemistry. The Li concentrations of these garnet crystals are very low, ∼5 µg/g. The measured range of δ7Li within some Franciscan garnets is 19‰, which falls well outside the uncertainty of the measurement (

This paper shows morphological similarity between aggregates separated from the lunar regolith ultra-fine size fraction and interplanetary dust particles (IDPs) collected in Earth’s stratosphere. It also demonstrates morphological difference between mentioned above and cometary particles from comet Wild 2 collected in the “Stardust” project. Given the number of lunar meteorites found on Earth, the Moon’s proximity to Earth, and its large surface area subject to high energy meteoroid impacts, makes it highly likely that all size spectrum of material ejected from lunar surface may have been grazed by Earth.

Hydrogen occurs at the near percent level in the most hydrated chondrites (CI and CM) attesting to the presence of water in the asteroid-forming regions. Their H abundances and isotopic signatures are powerful proxies for deciphering the distribution of H in the protoplanetary disk and the origin of Earth's water. Here, we report H contents and isotopic compositions for a set of carbonaceous and ordinary chondrites, including previously analyzed and new samples analyzed after the powdered samples were degassed under vacuum at 120 °C for 48 hours to remove adsorbed atmospheric water. By comparing our results to literature data, we reveal that the H budgets of both H-poor and H-rich carbonaceous chondrites are largely affected by atmospheric moisture, and that their precise quantification requires a specific pre-degassing procedure to correct for terrestrial contamination. Our results show that indigenous H contents of CI carbonaceous chondrites usually considered the most hydrated meteorites might be almost a factor of two lower than those previously reported, with uncontaminated D/H ratios differing significantly from that of Earth's oceans. Without pre-degassing, the H concentrations of H-poor samples (e.g., CVs chondrites) are also affected by terrestrial contamination. After correction for contamination, it appears that the amount of water in chondrites is not controlled by the matrix modal abundance, suggesting that the different chondritic parent bodies accreted variable amounts of water-ice grains. Our results also imply that (i) thermal metamorphism play an important role in determining the H content of both CV and ordinary chondrites but without affecting drastically their H isotopic composition since no clear D enrichment is observed with the increase of petrographic type and (ii) the D enrichment of ordinary chondrite organics does not result from the loss of isotopically light H2 induced by metal oxidation but is rather linked to the persistence of a thermally resistant D-rich component.

Supercritical CO2 appearing as bubbles in hydrothermal vents was identified in the south part of the Okinawa Trough using in situ Raman spectroscopy. Significantly, the N2 peak in supercritical CO2 is much larger than those in seawater and vent fluids, indicating that supercritical CO2 enriches N2 from the surrounding environment. Considering that the partial pressures of CO2 and N2 in the Earth’s proto-atmosphere were ~10–20 MPa, supercritical CO2 with high N2 was likely the dominant CO2 phase near the water-air interface in the early history of the Earth, which promoted the synthesis, pre-enrichment and preservation of amino acids and other organic matters that are essential to the origin of life.

Air particulate matter (PM) samples were collected over the period from May 2017 to January 2018 for determination of chemical elements. Sampling campaign is realized in Damascus, the capital of Syria, and conducted twice per week. PM samples were taken as two size fractions (PM2.5 and PM2.5-10) using ISAP air sampler. The results showed that the mass concentrations for PM2.5 were higher than those for PM10-2.5. The overall mean mass concentrations were 32.48 ± 14 μg/m3 and 18.9 ± 10 μg/m3 for PM2.5 and PM10-2.5, respectively. The PM2.5 samples were subjected to PIXE analysis in order to determine the major (Ca, S, Si, Fe, Al, K, Mg and Na) and trace elements (Cl, Pb, Zn, Ti, P, Mn, Cu, Sr, Zr, Br, V and Ni). Elemental composition data were modelled using cluster analysis and principal component analysis to determine particle source categories contributing to the air pollution. The identified sources of PM2.5 were (1) resuspended soil characterized by high concentrations of Si, Al, Fe and Mg; (2) traffic source identified by the presence of Pb, Br, and S; (3) heavy oil combustion characterized by association between Ni and V; (4) a mixed industrial source; and (5) agriculture activities (K, Ca and P). The concentrations of elements initiated from anthropogenic sources are much lower than those induced naturally from earth’s crust.

Summary Mn-based Li-excess cation-disordered rocksalt (DRX) oxyfluorides are promising candidates for next-generation rechargeable battery cathodes owing to their large energy densities, the earth abundance, and low cost of Mn. In this work, we synthesized and electrochemically tested four representative compositions in the Li-Mn-O-F DRX chemical space with various Li and F content. While all compositions achieve higher than 200 mAh g−1 initial capacity and good cyclability, we show that the Li-site distribution plays a more important role than the metal-redox capacity in determining the initial capacity, whereas the metal-redox capacity is more closely related to the cyclability of the materials. We apply these insights and generate a capacity map of the Li-Mn-O-F chemical space, LixMn2-xO2-yFy (1.167 ≤ x ≤ 1.333, 0 ≤ y ≤ 0.667), which predicts both accessible Li capacity and Mn-redox capacity. This map allows the design of compounds that balance high capacity with good cyclability.

The present work deals with the study of the effect of temperature on the thermal conductivity of Earth Fuller (Bentonite Clay) at different climatic conditions. First of all Earth Fuller brought from Barmer and Jodhpur were ground to fine-grained particles using a grinder and than micron size particles were obtained using the sieves of 186 µm, 150 µm, 125 µm, and 106 µm. The transient line heat source method based KD2 Pro Thermal Analyzer has been used to measure the thermal conductivity of the prepared samples in the temperature range from 10 to 70 °C. It was observed that at a fixed temperature, the thermal conductivity increases up to 40% (samples from Barmer) and up to 30% (samples from Jodhpur) with the increase in the particle size. Results exhibit that the thermal conductivity of the same sized particles of Earth Fuller at the same temperature is different due to varying climatic conditions. Whereas the temperature was increased from 10 to 70 °C, the thermal conductivity of the same sized particles also increases by nearly 20%.

Various lines of evidence suggest that material isotopically similar to enstatite chondrites may have accreted to the terrestrial planets. However, the enrichment of light Si isotopes in bulk enstatite chondrites is not easy to reconcile with the heavy Si isotopic composition of the Bulk Silicate Earth (BSE). To investigate the origin of the light Si isotopic composition of enstatite chondrites, we have obtained in situ Si isotope data and simultaneously major- and trace element data in silicate and metal phases of chondrules, a metal-troilite spherule, and matrix from the enstatite chondrites Sahara 97072 (EH3) and Indarch (EH4) using laser ablation split stream-ICP-MS, which combines femto-second LA-MC-ICP-MS and Quadrupole-ICP-MS. Silicates in chondrules show variations in δ30Si (‰ variations of 30Si/28Si relative to NBS-28) ranges from −1.06 ± 0.13‰ (2 S.E.) to −0.38 ± 0.11‰. δ30Si in matrix silicates ranges from −0.96 ± 0.18‰ to −0.22 ± 0.12‰. The δ30Si-value of silicate phases varies independently of Mg/Si, ruling out simple equilibrium condensation from nebular gas. Some silicates in both enstatite chondrites have δ30Si-values like CI chondrites, whereas Si in other silicates is isotopically lighter, suggesting that the precursor materials of EH chondrites were already depleted in heavy Si isotopes. The metal phases in the matrix show average δ30Si of −6.0 ± 0.6‰. In spite of different metamorphic grades, the fractionation of Si isotopes between matrix metal and silicates in Sahara 97072 and Indarch shows no systematic differences, and thus no re-equilibration of Si isotopes occurred between silicates and metal at metamorphic temperatures below 900 K. The δ30Si-value of metal from a metal-troilite spherule from Sahara 97072 (−8.24 ± 0.12‰) is lower than that of matrix metals. These differences were likely inherited from different formation environments of matrix- and spherule metal. If metal formation occurred under equilibrium conditions, then matrix metal may have formed at higher temperatures than the MTS metal. or at similar temperatures but slightly lower oxygen fugacities, or the MTS metal equilibrated with gas or silicates which were not incorporated into EH chondrites because they were lost from the EH chondrite formation region. Alternatively, the differences in δ30Si of different metals could also reflect variable kinetic isotope fractionation during the formation of metal and exsolution of perryite. The considerably lower δ30Si-values of bulk EH chondrites compared to CI- and other chondrites partly reflects the presence of Si bearing metal and partly silicates with isotopically light Si. The latter indicate loss of a heavy Si-rich silicate component from the EH3 formation region, presumably together with refractory elements. Although the Si isotopic composition of bulk EH chondrites precludes that these represent major building material of the Earth, the combination of complementary heavy Si isotope- and refractory element-enriched reduced materials and carbonaceous or ordinary chondrites could provide a match for the heavy Si isotopic composition of Earth.

The processes of planetary accretion or formation of the Earth and other celestial objects can be studied by using the ¹⁸²Hf-¹⁸²W chronometer which requires precise measurements of tungsten isotope ratios. Many comparative measurements for the isotopic composition of tungsten have been performed using either thermal ionization mass spectrometry (TIMS) or multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). Yet, calibrated measurements of tungsten isotope ratios, and, in turn, isotopic abundances and atomic weight, are still lacking. In this study, we report the first independent measurements of all tungsten isotope ratios in five commercial tungsten reagents, including the new NRC candidate isotopic reference material WOLF-1 by MC-ICP-MS with use of the-state-of-the-art optimized regression mass bias correction model and NIST SRM 989 isotopic rhenium as calibrator.

Argon release mechanisms and diffusivity were quantified for coarsely crystalline hypogene alunite [KAl3(SO4)2(OH)6] from Marysvale, Utah, and microcrystalline supergene alunite aggregates from Coober Pedy, South Australia. Prior to diffusivity studies, all alunite samples, sorted in the 500–200, 200–100, 100–50, 50–10, and 460 °C. Isothermal holding time and AGESME modelling using our calculated diffusion parameters indicate that alunite should preserve Ar quantitatively for long periods (4.0 Ga) at Earth and Mars surface conditions, and both hypogene and supergene alunite should preserve original formation ages, independently of precipitation mechanism.

REFe2 (RE = rare earth) phase has been considered to form spontaneously in Nd-Ce-Fe-B cast strips and inherit into sintered magnets. However, here we report that REFe2 phase, which is absent in starting strip, occurs in as-sintered magnet with an identical composition of 25 wt% Ce. More interestingly, the formation of REFe2 induces apparent Ce-enriched shell surrounding RE2Fe14B grain, which is further exacerbated in annealed magnet containing a higher fraction of REFe2 phase. Influences of increasing REFe2 fraction on magnetic performance are revealed. Above findings on REFe2 phase evolution and resultant Ce segregation may shed lights on fabricating high-performance Nd-Ce-Fe-B.

Redox states of the Archean Eon have been constrained by various lines of evidence, including atmospheric, photochemical, and ecological models, mass-independent fractionations of sulfur isotopes, Fe-depletion of paleosols, and preservation of diagnostic detrital minerals. Although these lines of evidence present seemingly consistent upper limits on pO2,g, they are conceptually contradictory about the redox state of Archean surficial environments. Atmospheric, photochemical, and ecological modeling studies suggest weakly reducing environments under redox states represented by moderate H2,g levels. However, current interpretations of Fe-depletion in paleosols and the preservation of detrital minerals are based on low O2,g levels at which the reducing detrital minerals are thermodynamically unstable and survive because of slow kinetics of oxidative weathering. In this study, we show that under the redox state indicated by the Archean pH2,g range, Fe2+ and reducing Fe(II)-minerals are actually thermodynamically stable and have no tendency to be oxidized. We emphasize that pH2,g values are orders of magnitude higher than pO2,g in the Archean atmosphere and that H2,g and O2,g are not in equilibrium. The redox states of Archean surface environments behave as though they were controlled by the more abundant H2 instead of the very low O2, as in modern anoxic basins. Weathering in this case should have involved non-redox acidic dissolution of Fe(II)-species or reductive reaction of Fe(III)-species. Fe(II)-depleted paleosols and the preservation of relatively reduced detrital minerals are natural consequences of their thermodynamic stabilities in the Archean Eon's reducing environments rather than slow kinetics of oxidizing reactions. After the appearance of oxygenic photosynthesis, probably in the middle/late Archean, locally oxygenated environments could have existed, while the atmosphere as a whole remained anoxic. The profile of redox states on the Archean surface seems to be a reverse analogue to the modern Earth. Although oxidizing dissolution of transition metals could happen in O2-oases, quick reduction of oxyanions by abundant reductants, such as aqueous Fe2+, Fe(II)-minerals, and H2, might have restricted riverine transport of oxyanions and potentially complicate the interpretation of signals of O2-whiffs in marine sediments.

Insect infestations are a major threat to the quality of stored grain. One method of insect control is to apply diatomaceous earth (DE), a non-chemical, inert dust that is composed of the ossified remains of diatoms. Diatomaceous Earth kills insects via abrasion and desiccation when the insect is exposed to a sufficient quantity of DE from contact on the grain surface. Therefore, good dust adhesion is desirable to ensure that the DE will come in contact with insects in sufficient quantity to provide the insect control expected. This study considered the adhesion ratio of three types of DE, Celite, Dryacide, and Diafil, on wheat and corn kernels. All three types of DE adhered better to wheat than to corn, and to higher moisture grain than lower moisture grain, and moisture content affected the adhesion on corn more than wheat. Dryacide had the lowest adhesion of the three DE tested at each condition. Dryacide's adhesion was significantly lower than at least one other DE in each test and was lower than both other DE for 12% moisture corn and 15% moisture wheat. Celite had the highest adhesion measured in each trial except for 15% moisture corn but was only significantly higher than Diafil for 12% moisture wheat. Additionally, higher surface roughness correlated with higher adhesion percentages, indicating that rougher diatomaceous earth formulations will be better at adhering to grain particles.

Two Neoproterozoic-Cambrian shale suites that consist of normal (NBS) and metal-rich (HMBS) black shales from the Tepla-Barrandian Unit, Bohemian Massif (Czech Republic) are studied in terms of their Cu, Zn, Cr and Re–Os isotopic compositions to improve our knowledge of elemental and isotopic mass balance of these elements in Earth's oceans in the past and the extent of surface oxygenation at the Neoproterozoic–Cambrian boundary. The rock compositions indicate that the inputs of Cu and Zn have been controlled by variable proportions of metal-rich authigenic and low-metal terrigenous sources, the latter having exceptionally low δ65Cu and partially δ66Zn. In this respect, our data confirm previous studies conclusions that organic-rich sediments with high a terrigenous flux play an important role in the sinking of light Zn in the oceans and provide new evidence that these types of rocks also represent the currently unidentified burial of very light Cu in the ocean. The chromium isotopic composition reveals a complex history of Cr uptake and fractionation through the dominant Cr input from different terrigenous sources with variable δ53Cr followed by Cr fractionation that was controlled by redox states (NBS). On the other hand, mixing and/or continuous equilibrium isotopic exchange between seawater and hydrothermal Cr was the dominant process for the HMBS. The Re–Os contents of the NBS were controlled by hydrogenous components, which yield a poorly defined Re–Os age for the least disturbed samples of 555 ± 60 Ma, indicating an open-system behavior, while the HMBS Re–Os composition was largely influenced by hydrothermal fluids during deposition. The calculated authigenic δ65Cu, which is similar to that in the present-day ocean, and highly positive δ53Cr values of the HMBS suggest high levels of surface oxygenation during the Neoproterozoic–Cambrian transition. Furthermore, the authigenic δ66Zn, which is indistinguishable from that in the present-day ocean, may imply a constant Zn isotopic composition of the oceans from the Neoproterozoic because of the well-balanced cycle of phosphates, which were strongly adsorbed by Fe-hydroxides. The radiogenic nature of the initial 187Os/188Os (~0.6), although with a high associated error, seems to not confirm previous indications of an abrupt increase of seawater 187Os/188Os during the late Neoproterozoic due to the large-scale radiogenic Os flux into the ocean.

As the formation and development of organic-inorganic interaction continues, people have came to realize the importance of organic matter during the process of organic matter maturing and generating hydrocarbon. Deep fluids act as the carrier of inner earth substances as it previously carried massive inorganic matter from deep earth. The injection of deep fluids provide sedimentary basin with hydrogen sources and catalyst, which promotes the maturation and evolution of organic matters within basins. By providing essential carbon sources for inorganic reaction, deep fluids also took apart in inorganic hydrocarbon generation reaction. This paper collected recent achievements in regards to organic matter hydrogenation reaction and inorganic hydrocarbon generation reaction such as F-T synthesis. By giving a detailed analysis of the effect of extraneous hydrogen sources and catalyst on organic maturation and hydrocarbon-producing process, this paper confirms the “increasing hydrocarbon yield” effect of deep fluid. Keywords: Deep fluid, Organic-inorganic interaction, “Increasing hydrocarbon yield” effect, Extraneous hydrogen sources, Catalyst, Carbon sources

Tektites are mm to cm sized glassy objects generated through high-energy meteoroid impacts on the surface of the Earth under high temperature and pressure, and reducing conditions. They are the products of large-scale catastrophic events in Earth’s history and can be used to understand the behavior of moderately volatile elements (e.g., K and Zn) during impact vaporization events. Here, we report bulk K isotopic compositions of tektites from three different strewn fields and “in-situ” profile analysis of both K and Zn isotopes in one complete tektite. All tektites span a narrow range in their K isotopic compositions (δ41KBSE: −0.10 ± 0.03‰ to 0.16 ± 0.04‰), revealing no discernible K isotopic fractionation from the Bulk Silicate Earth (BSE) and upper continental crust materials, which is consistent with previous results. In contrast, Zn isotopes show a large variation (δ66Zn: −0.39 ± 0.02‰ to 2.38 ± 0.03‰) even within one specimen. In order to provide a coherent explanation for the different behavior of moderately volatile elements (K, Zn and Cu), we have conducted thermochemical calculations to compute the partial vapor pressures of Cu2O, K2O, and ZnO dissolved in silicate melts as a function of temperature, pressure, oxygen and chlorine fugacities. In a large range of the parameter space, the calculations show that Cu and Zn can be vaporized much easier than K and thus produce large isotopic fractionation. In contrast, the lithophile element K is more prone to remain in the silicate melt because of its very low activity coefficient in the melt, and thus the K isotopes remain unfractionated. This study provides new constraints on the formation of tektites and is consistent with a “bubble-stripping” model to explain the extreme water and volatiles depletion in tektites.

Mobile nuclear magnetic resonance (NMR) operating in Earth's magnetic field is adapted to detect leaked or spilled oil trapped in or under sea ice without the need to place any personnel on the ice. A helicopter placed a 6-meter diameter NMR coil system weighing approximately 1000 kg on 92 cm-thick ice surrogate and detected the equivalent of 1 cm thick oil under the ice surrogate in 3–1/2 min.

A series of Al100-a-bNia(La1-xGdx)b metallic glass ribbons, where a = 9–10, b = 4.5–5.5 and x = 0–1, were prepared by melt-spinning under identical conditions for investigating the dependence of crystallization behavior on the mutual substitution between La and Gd. In general, as the rare earth gradually changes from full La to full Gd, the thermal stability decreases and the formation of α-Al as primary phase is favored. A parameter taking the number and strength of various solvent-solute bonds into account was proposed to evaluate the thermal stability of present and other Al-TM-RE (TM-transition metal and RE-rare earth) metallic glasses, and good agreement was achieved between the theory and experimental results. Substitution of La by Gd releases additional “free Al atoms” and enhances the segregation of solvent Al atoms, therefore promoting the formation of α-Al at the first crystallization stage.

A long-standing unresolved problem in understanding Earth's deep carbon cycle is whether crustal carbon is recycled beyond arc depths. While isotopic signatures of eclogitic diamonds and their inclusions suggest deep recycling of crustal material, the crustal carbon source remains controversial; seafloor sediment – the widely favored crustal carbon source – cannot explain the combined carbon and nitrogen isotopic characteristics of eclogitic diamonds. Here we examined the carbon and oxygen isotopic signatures of bulk-rock carbonate for 80 geographically diverse samples from altered mafic-ultramafic oceanic crust (AOC), which comprises 95 vol% of the crustal material in subducting slabs. The results show: (i) AOC contains carbonate with δ 13 C values as low as −24‰, indicating the presence of biogenic carbonate; (ii) carbonate in AOC was mainly formed during low-temperature (

Although utilization of commercial products based on diatomaceous earth, an insecticide of the natural origin, plays a very important role in the integral protection of stored grains, the effect of their application on the rheological quality of small grains is poorly exploited. Therefore, the aim of this research was to employ GlutoPeak and Mixolab rheological devices in order to compare the impact of three diatomaceous earths (DEs) (Protect-It and two inert dusts originated from Serbia) application on the rheological properties of wheat, triticale and rye flour dough. While moisture and protein content did not differ in treated and untreated grain samples, application of all three DEs in two triticale varieties led to an increase in the wet gluten content and Mixolab water absorption, as well as a decrease in the gluten strength, as indicated by gluten index and GlutoPeak maximum torque values. Treated rye samples have also exhibited a decrease in dough maximum consistency and stability and greater protein structure weakening in comparison to untreated sample. The mentioned changes in rheological behaviour were not noticed in wheat varieties treated with DEs. The major changes were recorded in rheological behaviour of triticale and rye starch component which showed a decrease in maximum peak torque and hot paste stability after grain treatment with DEs. In general, the influence of DEs on rheological properties of small grains was highly species and varietal dependent, where more pronounced differences between treated and untreated grains were noticed in stronger varieties.

Fluids in the deep crust and upper mantle appear to have played roles in the long-term evolution of the subcratonic lithospheric mantle and the stabilities of the continents, in the geochemical cycles of the elements from subduction zones to Earth’s surface environment, and in the formation of diamonds. Much evidence of the chemistry of deep fluids has accumulated from studies of fluid inclusions in diamonds and xenoliths. But the origins of the fluids and their behavior are still unclear. In part, this is due to the lack of a comprehensive theoretical model of aqueous, high-pressure fluids. Traditional models have used a C-O-H-type of model, which contains no major rock-forming elements or aqueous ions or metal-complexes. In the present study, we use experimentally measured solubility data for multicomponent K-free eclogite, K-free peridotite and K-bearing peridotite rocks at upper mantle conditions from the literature to construct aqueous speciation solubility models that enabled calibration of the thermodynamic properties of ions and metal-complex species involving the elements Na, K, Mg, Ca, Fe, Al, Si, and C in an extended Deep Earth Water (DEW) model. New equilibrium constants were retrieved for the aqueous bisilicate anion, a silica trimer, silicate complexes of Ca, Fe, and Al, a silicate complex of Mg and bicarbonate, and formate complexes of Fe and Ca. The aqueous speciation and solubility model also took account of decreases in the activity of water and aqueous activity coefficients of neutral dissolved gases and included consideration of H 2 CO 3 0 . Based on the temperature and pressure dependences of the equilibrium constants, and supporting data covering a wide range of conditions, we then developed aqueous equation of state characterizations of the ions and metal-complex species. Overall, the results form a basis for modeling fluid-rock interactions under upper mantle conditions consistent with experimental solubility measurements.

Iron is among the most abundant elements in Earth's crust and is also a major aqueous solute in a variety of hydrothermal settings, yet major questions remain regarding the solubility and speciation of iron at hydrothermal conditions. Here, we conducted hydrothermal diamond-anvil cell experiments using synchrotron-radiation micro-XRF and XANES analyses as well as Raman spectroscopy, in situ at hydrothermal temperatures and pressures, to characterize the solubility and speciation of iron in fluids buffered by a variety of mineral assemblages. Our experiments included the assemblages hematite-magnetite (HM), fayalite-magnetite-quartz (FMQ), and magnetite-pyrite-pyrrhotite (MPP). Our results indicate highest solubilities of HM in HCl solutions. In sodium chloride solutions of similar molalities, FMQ shows higher Fe solubility than MPP. XANES data are interpreted as preponderance of ferrous iron in all experiments. Comparison of XANES spectra of these solutions with calculated XANES spectra from the literature indicates octahedral FeClx(H2O)6−x2−x (x = 0–3) as predominant Fe(II) species at lower Cl-Fe ratios, and suggests additional tetrahedral FeCl42− or FeCl3(H2O)− at high Cl-Fe ratios. Raman spectra to 600 °C show that the predominant species in ferric iron solutions is FeCl2(H2O)4+ at temperatures less than 100 °C, which transitions to FeCl4− between 100 and 200 °C. An additional Raman band that occurred in some spectra of a H2O + HCl fluid equilibrated with hematite ± magnetite at temperatures greater than 300 °C may originate from an FeCl3(H2O)x (x = 0–3) species. All Raman spectra of ferrous iron solutions show a fairly broad band at about 280 cm−1, which can be interpreted to stem from Fe(II)–Cl vibrations of FeCl3(H2O)x− (x = 0–3) (point group D3h) species or, at low Cl-Fe ratios of about two or less, from octahedral FeClx(H2O)6−x2−x (x = 0–3) species. These results provide important constraints on the hydrothermal mobilization of iron and fluid-rock reactions involving iron- and chloride-bearing fluids.

Sediments collected from Lake Towuti, an ultramafic-hosted lake in Indonesia, preserve a visible alternating pattern of red and green sediments due to variations in clay mineral and Fe-oxide composition and abundance consistent with changes in iron oxidation state through time. Spectral, mineralogical, and chemical analyses on soils, river, and sediment samples from across the lake and its catchment were carried out to better understand the starting composition of these sediments and the processes that affected them before and after deposition. Despite high Fe abundances in all samples and abundant Fe oxides in lateritic source regions, mineralogical analyses (X-ray diffraction (XRD) and Mossbauer spectroscopy) of the modern lake sediment show almost no well-crystalline iron oxides. In addition, sequential Fe extractions suggest an increasing proportion of easily extractable, poorly crystalline (X-ray amorphous) material with burial depth. XRD, bulk chemistry, and visible-near infrared (VNIR) spectral reflectance measurements demonstrate that clay mineralogy and bulk chemistry can be inferred from VNIR data. These results provide evidence for variations in Fe mineralogy and crystallinity based on location in this source to sink system. Understanding how the mineralogy and chemistry of sediments within a ferruginous lake basin are affected by transport, chemical alteration, physical alteration, and deposition from source to sink on Earth, and the degree to which these trends and underlying processes can be inferred from chemical and spectral properties, may provide useful direction in assessing paleoenvironmental conditions in other terrestrial lakes as well as ancient lacustrine environments preserved in the stratigraphic record of Mars.

The radiation of macroscopic animals in the Early Cambrian, commonly be called as ‘Cambrian explosion’, had a close relationship with Earth oxygenation. These macrofossils are widely preserved within the Early Cambrian in the northern and western Yangtze Craton. In order to show the casual relationship between animal evolution and Earth redox environment, Mo content and isotopic composition analyses have been conducted on dolomites of the Tianzhushan Formation and the black shales of the Shuijingtuo Formation from the lowermost Cambrian profile in the eastern Huangling dome, northern Yangtze Craton. The calcitic dolostones from the Tianzhushan Formation display lower concentrations of Mo contents (0.055–0.666 ppm) than that of the black silty shales from the Shuijingtuo Formation (6.0–172 ppm). This magnitude difference is most likely related to the different lithologies due to Mo enrichment in shales. The Mo isotope values (δ98/95Mo) of the calcitic dolostones for the Tianzhushan Formation vary from −0.73‰ to 0.41‰. In comparison, the black sandy shales from the Shuijingtuo Formation exhibit δ98/95Mo of −1.04–1.84‰, including 5 samples from the earliest Shuijingtuo Formation displaying systematically higher δ98/95Mo values (0.09–1.84‰) than those of the other 5 samples from upper layers (δ98/95Mo = −1.04 to −0.19‰). These geochemical data suggest that the redox environment of the early Cambrian is fluctuating, and the peak oxygenation of the ocean had already reached a level similar to modern environments. According to the Mo concentrations and δ98/95Mo data, the sedimentary succession can be divided into five intervals, which are closely correlated to the episodic evolution of early life in the Cambrian. Together with the available published data from other profiles in the Yangtze Craton, our new data reveal that the higher oxidation environment had a positive effect on the evolution of early life.

Moderately volatile elements show variable depletion in terrestrial planets compared to the Sun. Isotopic ratios can be used as a signature of the processes at the origin of this depletion. Using a new method, the Sn stable isotope composition and elemental abundance in 36 primitive meteorites (chondrites) have been characterised to high precision. Significant mass-dependent Sn isotope variations are found within chondrites. The widest isotopic range is observed for the ordinary chondrites (−1.1 ‰ to +0.5 ‰ in δ122/118Sn, representing the difference in the 122Sn/118Sn ratio of the sample relative to our in-house standard, Sn_IPGP), with the ordinary chondrite groups extending to lighter isotopic compositions in the order H > L > LL, while carbonaceous and enstatite chondrites are heavier and occupy narrower compositional ranges. Tin and Zn isotope and concentration data are strongly correlated, particularly in ordinary chondrites, from which both sets of data were obtained on the same rock powders. Given the difference in geochemical behaviour (Zn lithophile/chalcophile and Sn chalcophile/siderophile) of these elements, this suggests that the primary control on the isotope and abundance variations is volatility. Chondrite groups show variability increasing with petrographic types, suggesting a secondary control from parent-body metamorphism. The isotopic composition of the bulk silicate Earth (BSE; δ 122/118Sn = 0.49 ± 0.11 ‰) overlaps with the carbonaceous chondrites (δ 122/118Sn = 0.43 ± 0.12 ‰; excl. CR and CK). Despite isotopic similarities for almost all isotopic systems, EH chondrites have Sn isotope compositions that are distinct from the bulk silicate Earth (δ 122/118Sn = 0.18 ± 0.21 ‰). Therefore, an enstatite chondrite-like bulk Earth requires that isotopically light Sn was lost from the silicate Earth, possibly into the metallic core or a sulphide matte, or by evaporative loss from Earth or its precursors.

Multiple mechanisms have been proposed to induce fractionation of tin in ores and rocks. Experimental evidence to support and characterize the causes for fractionation is lacking. Here, we present laboratory vapor-induced and redox-driven experiments to resolve the directionality and relative magnitude of fractionation caused by these geologically prominent mechanisms. Vapor-induced fractionation without redox reactions at 150 °C resulted in the residual solution becoming isotopically lighter by 0.15‰ (δ124Sn with all values reported in comparison to NIST 3161A). Tin chloride solutions that were electrolytically reduced to form metal produced residual solutions that were 0.40‰ heavier (δ124Sn). The reduced metal from these experiments was lighter than the solutions and starting materials. These experiments confirm that heavier tin isotopes are favored in a stronger bonding environment associated with oxidation, and that the vapor favors heavier tin in SnCl4. Empirical confirmation of the magnitudes and directions of tin isotope fractionation determined through experimentation are evident in the comparison of the isotopic composition of cassiterite ores from contrasting mineralizing environments. Pegmatites and associated greisen ores that formed deep within the Earth, and so experienced redox reactions without vapor partitioning (Etta, South Dakota; Elsmore, New South Wales) display a variation of only 0.8‰ (δ124Sn). In contrast, cassiterite that formed from vapor-rich fluids in volcanic to subvolcanic environments, and so experienced both redox and vapor fractionation mechanisms (Taylor Creek, New Mexico, Durango, Mexico; Potosi and Oruro, Bolivia) display a much larger range of cassiterite values, of up to 2‰ (δ124Sn). It is likely that tin isotope fractionation via these mechanisms contribute to the observed variations in igneous rocks.

A methodological proposal is presented for uranium prospection using multiple regression of aerogeophysical data (gamma-spectrometry and magnetometry) via a case study in a large and geologically complex area in central Brazil, where known uranium deposits occur. The model seeks to identify and minimize the background variability in uranium concentration for the different lithotypes present in the study area. The multiple regression model is obtained based on the thorium channel data, the eTh/K, eU/K ratios and the magnetic field analytical signal amplitude. Areas with high uranium concentration, in various lithotypes, are highlighted by the subtraction of the regression model obtained from the uranium values measured during the aerial survey. The study area covers part of the southeastern region of the Goias state, including the Catalao I Complex, which hosts a phosphate mine and includes well-known uranium anomalies as well as rare earth elements associated with the phosphate deposits. The proposed method reveals the presence of anomalous areas as a function of the independent variables, represented by the geophysical properties and the different lithotypes that constitute the geological environment. Besides areas with high uranium contents associated with the Catalao I Complex, new anomalous areas associated with other types of geological environments could be identified. The targets found by the application of the proposed method, were checked in the field via geochemical analysis of rock samples in addition to in situ measurements with a portable gamma-spectrometer. Field measurements showed that, in all cases analyzed, uranium contents presented values above the average concentration of this radioelement in the earth's crust. Geochemical analyzes results from the collected samples confirmed our results by revealing uranium levels ranging from 3.5 to 15.9 ppm. The presented method was successful in identifying specific sites of high uranium concentration via aerogeophysical data, previously concealed by the geological background.