Mineralogy Of Earth Research Articles

The EMIT mission information yield for mineral dust radiative forcing

The net direct radiative effect of mineral dust is a large uncertainty in global radiative forcing. To address this challenge, NASA's Earth Mineral dust source InvesTigation (EMIT) will map the surface mineralogy of Earth's desert dust source regions, constraining the composition of mineral dust aerosol for use in Earth system models (ESMs). This mission foreshadows multiple future global spectroscopic investigations for which coupling with ESMs will play a critical role. Planning such experiments requires a methodology for assessing the impact of uncertain remote observations on ESM accuracy. We design and implement an end-to-end simulation of the EMIT mission, leveraging Bayesian statistical methods and Monte Carlo sampling to analyze uncertainties in the retrieval and processing of EMIT data products. Special focus is placed on those uncertainties caused by atmospheric water vapor and aerosol loading conditions likely to be encountered by EMIT. We apply these results to a single-column configuration of the Community Earth System Model (CESM), revealing the potential impact of EMIT observations on radiative forcing estimates. We show that EMIT data stand to significantly reduce uncertainty in estimates of the dust direct radiative forcing attributable to uncertainties in surface mineralogies that are input to ESMs, and that the information gain for radiative forcing comes predominantly from better constraining iron oxides, which dominate the shortwave radiative effects of aerosol dust.

Assessing Geological Resource and Risk Associated Radiation While Refining Opal Minerals Using Local Mechanism

The current study concentrated on the risk associated with naturally occurring radioactive materials in opal minerals and the method of refinement from the opal deposit site. The study's goal was to raise awareness of people who cause disease, improper use of expectations, and of better income generated in scientific ways. Radiation exposure has been associated with most forms of leukemia and with cancers of many organs, such as the lung, breast and thyroid gland, but not with certain other organs, such as the prostate gland. Mineworkers are exposed to radiation when extracting minerals from the earth's crust, with the associated radiological risks being assessed. Earth mineralogy is associated with environmental risks during mining and refining, particularly in certain aspects. Opal is most commonly found in Wollo, Ethiopia's northernmost region. The mechanism people used to refine opal Minerals at Wegel Tena often use rudimentary tools, such as a hammer and chisel, to extract the opal from the exposed seam along the flank of the canyon. The people living in Wogel Tena unknowingly export opal minerals to traders. Nowadays, the government's energy and mineral ministers are concerned about the preservation of tourist attractions and commercial centers using scientific methods. The local opal trader was unconcerned about people's safety or the diversion of mining resources. The new opal deposit was discovered in the village of Wegel Tena. Unlike previous Ethiopian opals, the new material is mostly white, with a little brown opal, fire opal, and a colorless "crystal" opal thrown in for good measure. When soaked in water, the opaque-to-translucent opals become transparent, showing a remarkable hydrophane character.

Charge disproportionation and site-selective local magnetic moments in the post-perovskite-type Fe2O3 under ultra-high pressures

The archetypal 3d Mott insulator hematite, Fe2O3, is one of the basic oxide components playing an important role in mineralogy of Earth’s lower mantle. Its high pressure–temperature behavior, such as the electronic properties, equation of state, and phase stability is of fundamental importance for understanding the properties and evolution of the Earth’s interior. Here, we study the electronic structure, magnetic state, and lattice stability of Fe2O3 at ultra-high pressures using the density functional plus dynamical mean-field theory (DFT + DMFT) approach. In the vicinity of a Mott transition, Fe2O3 is found to exhibit a series of complex electronic, magnetic, and structural transformations. In particular, it makes a phase transition to a metal with a post-perovskite crystal structure and site-selective local moments upon compression above 75 GPa. We show that the site-selective phase transition is accompanied by a charge disproportionation of Fe ions, with Fe3±δ and δ ~ 0.05–0.09, implying a complex interplay between electronic correlations and the lattice. Our results suggest that site-selective local moments in Fe2O3 persist up to ultra-high pressures of ~200–250 GPa, i.e., sufficiently above the core–mantle boundary. The latter can have important consequences for understanding of the velocity and density anomalies in the Earth’s lower mantle.

Analysing the proximal gamma radiometry in contrasting Mediterranean landscapes: Towards a regional prediction of clay content

The analysis of γ-radiometric data from proximal soil sensing measurements can be used to predict key soil properties for environmental and agricultural issues. These predictions require prior calibrations that use a large sampling of field data that could be significantly reduced if regional predictions can be established. However, such predictions may be challenging for Mediterranean regions because of the highly contrasted soils and specific geopedological characteristics (sedimentary rocks, low weathering, etc.). Our study focuses on the regional prediction of a key soil property (clay content), within highly contrasting geopedological groups (GPG) from the Languedoc region. The aims of the research were (i) to understand the relationship between γ-radiometric data and the clay content within the different complex GPGs and (ii) to predict the clay content from γ radiometry with a regional calibration based on the GPG as an auxiliary variable. A proximal soil survey using the γ radiometer, called “The Mole”, was conducted in 8 areas of the Languedoc region. The plots were selected over different GPGs that are representative of the soil diversity and materials according to their weathering intensity and igneous components. In total, 242 sites were sampled based on a random grid cell for soil laboratory measurements. The soil texture and stoniness were analysed, and the particle size fractions were separated for mineral identification via X-ray diffraction. The activity of 232Th [1 to 71bq/kg] and 40K [40 to 771bq/kg] exhibits the largest range between the different GPGs, which spans the range of values measured in previous European studies. The relationship between the clay content and 232Th is significant at a regional level [R2=0.60; RMSE=42g/kg]. The residuals are significantly distributed according to the different GPGs. A new linear model based on the 232Th activity and the GPGs improves the prediction of the clay content [R2=0.72; RMSE=35g/kg]. Our study showed that ground γ radiometry can be used to predict the clay content within a complex Mediterranean sedimentary context. The 232Th radionuclide is the best predictor. The disturbance of the relationship between the 232Th and the clay content corresponds to the fine earth mineralogy type and the proportion of igneous pebbles.

Statistical analysis of mineral diversity and distribution: Earth's mineralogy is unique

Earth's mineralogical diversity arises from both deterministic processes and frozen accidents. We apply statistical methods and comprehensive mineralogical databases to investigate chance versus necessity in mineral diversity-distribution relationships. Hundreds of mineral species, including most common rock-forming minerals, distinguish an “Earth-like” planet from other terrestrial bodies. However, most of Earth's ∼5000 mineral species are rare, known from only a few localities. We demonstrate that, in spite of deterministic physical, chemical, and biological factors that control most of our planet's mineral diversity, Earth's mineralogy is unique in the cosmos.

Implication of zeta potential and surface free energy in the description of agricultural soil quality: Effect of different cations and humic acids on degraded soils

Here we present results of our study about the effect of natural organic matter in the adsorptions processes of commercial humic acid (HA) on the physicochemical properties, stability, and structure of an agricultural olive soil. Our soil belongs to the loamy texture class and gives a medium-low chemical fertility. Its organic carbon content is very low (0.40%), which could be explained by the Mediterranean climate type in which the soil developed. From the fine earth mineralogy, we conclude that smectite was the most abundant mineral in our soil.We first demonstrated that HA effectively adsorbs onto soil, mainly at basic pH. Electrophoresis measurements of soil particle suspensions as a function of pH in the presence and absence of humic acid clearly demonstrate the adsorption of negatively charged entities onto smectite in the soil. This effect is more significant when the soil contains natural organic matter, which confirms the mordant character of this matter in native soil.Analysis of surface free energy components leads to the conclusion that humic acid molecules impart a significant electron donor character to the soil particles, which in turn decreases their hydrophilicity. All collected data were used to interpret the final soil structure. Our results are consistent with fabric images obtained by scanning electron microscopy of natural samples that present the major aggregation state. Interpretation of these results can be explained by a combination of electrical and thermodynamic interaction, electrostatic forces, double-layer repulsion, van der Waals attraction, and hydrophilic/hydrophobic repulsion/attraction.

Deep Earth mineralogy revealed by ultrahigh-pressure experiments

AbstractUltrahigh-pressure and -temperature (P-T) experimental techniques have progressed rapidly in recent years. By combining them with X-ray diffraction measurements at synchrotron radiation facilities, it is now possible to examine deep Earth mineralogy in situ at relevant high P-T conditions in a laser-heated diamond anvil cell (DAC). The lowermost part of the mantle, known as the D″ layer, has long been enigmatic because of a number of unexplained seismological features. Nevertheless, the discovery of a phase transition from MgSiO3 perovskite to ‘post-perovskite’ above 120 GPa and 2400 K indicates that post-perovskite is a principal constituent in the lowermost mantle, which is compatible with seismic observations. The ultrahigh P-T conditions of the Earth’s core have not been accessible by static experiments, but the structure and phase transition of Fe and Fe-alloys are now being examined up to 400 GPa and 6000 K by laser-heated DAC studies.

The mineralogy and geochemistry of the Wicheeda Carbonatite Complex, British Columbia, Canada

The Wicheeda Carbonatite Complex, located 80km northeast of Prince George in British Columbia, Canada, has been historically explored for its REE potential but, until recently, there has been very little extensive exploration or scientific study. The Complex consists of a carbonatite plug with a series of carbonatite and potassic-syenite dykes and sills emplaced into the upper Cambrian and lower Ordovician Kechika Group. The carbonatite is classified as a calcio- to ferro-carbonatite. Sodic-fenitization is common around the carbonatite and the degree of alteration and frequency of syenite occurrences increase away from the carbonatite plug. The rare earth mineralogy of the Wicheeda carbonatite was defined through the use of petrography, scanning electron microscopy, electron probe microanalysis, and single-crystal X-ray diffraction. The REE mineralogy is complex, with multiple stages of primary, late-stage, rapidly cooling crystallization. The mineralogy consists of Ca-REE-fluorocarbonates [including bastnäsite-(Ce), parisite-(Ce), and synchysite-(Ce)], Ba-REE-fluorocarbonates [including cordylite-(Ce), kukharenkoite-(Ce), cebaite-(Ce), huangnoite-(Ce), and qaqarssukite-(Ce)], ancylite-(Ce), monazite-(Ce), euxenite-(Y) and allanite-(Ce); the majority of which are LREE-rich. The REE minerals typically form in anhedral aggregates with strontianite, calcite, dolomite, and ankerite. The aggregates range in size from a 1–2 mm but have been observed up to 7cm. The Ca-REE-fluorocarbonate minerals generally form as syntaxial intergrowths whereas the other REE minerals form individual crystals. The REE content varies throughout the carbonatite intervals with an average of 9663ppm. Evidence from the Wicheeda Carbonatite Complex and comparisons with other worldwide carbonatites suggest that the complex is derived from low-degree partial melts extracted from metasomatized lithospheric mantle.

A comparative geochemical study of Mars and Earth basalt petrogenesis

Geochemical data, from the Mars Meteorite Compendium web site, for 13 basaltic meteorites, possibly from only four localities on Mars, are used to study Martian petrogenetic processes. To achieve this goal, an exploratory data analysis technique, multidimensional scaling (MDS), is used to quantitatively assess the relative behavior (measured with correlation coefficients) of 160 incompatible element ratios involving 25 “trace” elements. The ratios behave as in Earth basalts, suggesting that relative element incompatibility is similar in both planets. Because mineralogy controls incompatibility, the mineralogy of Earth and Mars mantles appears similar. In addition, results suggest that ratios involving elements with highly different incompatibility (e.g., La/Yb) are dominantly controlled by % melting. Plots of SiO2 (pressure proxy; decreases with increasing pressure) versus La/Yb and Nb/Y (decrease as melting increases) imply that Mars basalts, like Earth tholeiites, reflect high percentages of melting, but opposite to Earth, % melting appears to increase with increasing pressure. The moderately correlated, positive, SiO2–La/Yb Mars relationship parallels highly correlated Lunar KREEP data and contrasts with Earth’s negative correlation. The positive relationships may reflect restricted mantle convection in some (Mars and the Moon are smaller) planetary bodies. Using similarly incompatible element ratios that are sensitive to source composition, to compare Mars and Earth with MDS, Mars sources most resemble depleted Earth mantle. Additionally, these ratios group Mars sources into enriched, depleted, and intermediate types. The groupings are the same as those suggested by isotopes, and we conclude that trace element data support the hypothesis that chemical variation in Mars may reflect crystallization of a Mars magma ocean. The natural patterns in ratios and samples revealed using MDS, which has no a priori information about relationships, support integrity of the geochemical data set, despite potential shortcomings such as small sample sizes, alteration, and weathering. However, whether the meteorites are representative of Mars as a whole is unknown.

High-pressure experimental geosciences: state of the art and prospects

Abstract This paper aims at reviewing the current advancements of high pressure experimental geosciences. The angle chosen is that of in situ measurements at the high pressure (P) and high temperature (T) conditions relevant of the deep Earth and planets, measurements that are often carried out at large facilities (X-ray synchrotrons and neutron sources). Rather than giving an exhaustive catalogue, four main active areas of research are chosen: the latest advancements on deep Earth mineralogy, how to probe the properties of melts, how to probe Earth dynamics, and chemical reactivity induced by increased P-T conditions. For each area, techniques are briefly presented and selected examples illustrate their potentials, and what that tell us about the structure and dynamics of the planet.

Phase transition and metallization of FeO at high pressures and temperatures

[1] Wustite, Fe1-xO, is an important component in the mineralogy of Earth's lower mantle and may also be a component of the core. Therefore its high pressure-temperature behavior, including its electronic structure, is essential to understanding the nature and evolution of Earth's deep interior. We performed X-ray diffraction and radiometric measurements on wustite in a laser-heated diamond anvil cell, finding an insulator-metal transition at high pressures and temperatures. Our data show a negative slope for this apparently isostructural phase boundary, which is characterized by a volume decrease and emissivity increase. The metallic phase of FeO is stable at conditions of the lower mantle and core, which has implications for the highP-Tcharacter of Fe-O bonds, magnetic field propagation, and lower mantle conductivity.

Equation of state and phase diagram of FeO

Wüstite, Fe 1 − x O, is an important component in the mineralogy of Earth's lower mantle and may also be a component in the core. Therefore the high pressure, high temperature behavior of FeO, including its phase diagram and equation of state, is essential knowledge for understanding the properties and evolution of Earth's deep interior. We performed X-ray diffraction measurements using a laser-heated diamond anvil cell to achieve simultaneous high pressures and temperatures. Wüstite was mixed with iron metal, which served as our pressure standard, under the assumption that negligible oxygen dissolved into the iron. Our data show a positive slope for the subsolidus phase boundary between the B1 and B8 structures, indicating that the B1 phase is stable at the P–T conditions of the lower mantle and core. We have determined the thermal equation of state of B1 FeO to 156 GPa and 3100 K, finding an isothermal bulk modulus K 0 = 149.4 ± 1.0 GPa and its pressure derivative K 0′ = 3.60 ± 0.4. This implies that 7.7 ± 1.1 wt.% oxygen is required in the outer core to match the seismologically-determined density, under the simplifying assumption of a purely Fe–O outer core.

High-pressure melting of wustite

Iron oxide (FeO) is an important component in the mineralogy of Earth’s lower mantle and possibly its core, so its phase diagram is essential to models of the planet’s interior. The melting curve of wustite, Fe 0.94 O, was determined up to 77 GPa and 3100 K in a laser-heated diamond anvil cell. Melting transition temperatures were identified from discontinuities in the emissivity vs. temperature relationship within the laser-heated spot. The melting curve exhibits no obvious kinks that could be related to a subsolidus transition in wustite, but there is evidence for a two-phase loop at pressures below 30 GPa. Comparison of these results to previous studies on Fe, Fe-O, and Fe-S confirms that the melting point depression in the Fe-O system remains significantly less, by a factor of 2 or more, than that in the Fe-S system up to pressures exceeding 80 GPa.

Development of Multianvil Techniques for Studies in Deep Earth Mineralogy

Aspects of development of experimental techniques at Geodynamics Research Center (GRC), Ehime University, using Kawai-type multianvil apparatus (KMA) for various studies in deep Earth mineralogy, have been reviewed in conjunction with the author’s scientific achievements in this field. Precise measurements of some physical properties of minerals at the pressure and temperature conditions corresponding to certain depths of the lower mantle are now possible, by combinations of synchrotron radiation, advanced anvil materials, new cell designs, and ultrasonic and other techniques using KMA. KMA has also been used to synthesize ultrahard nano-polycrystalline diamond (NPD) by direct conversion from graphite. NPD has potential as new hard material for generation of higher pressures, and challenges in producing large (∼1 cm) NPD and its application to various apparatus have just started at GRC and other related laboratories.

Some recent advances in understanding the mineralogy of Earth's deep mantle

Understanding planetary structure and evolution requires a detailed knowledge of the properties of geological materials under the conditions of deep planetary interiors. Experiments under the extreme pressure-temperature conditions of the deep mantle are challenging, and many fundamental properties remain poorly constrained or are inferred only through uncertain extrapolations from lower pressure-temperature states. Nevertheless, the last several years have witnessed a number of new developments in this area, and a broad overview of the current understanding of the Earth's lower mantle is presented here. Some recent experimental and theoretical advances related to the lowermost mantle are highlighted. Measurements of the equation of state and deformation behaviour of (Mg,Fe)SiO3 in the CaIrO3-type (post-perovskite) structure yield insights into the nature of the core-mantle boundary region. Theoretical studies of the behaviour of MgSiO3 liquids under high pressure-temperature conditions provide constraints on melt volumes, diffusivities and viscosities that are relevant to understanding both the early Earth (e.g. deep magma oceans) and seismic structure observed in the present Earth (e.g. ultra-low-velocity zones).

Elastic properties of high-pressure phases and implications for the temperature and mineralogy of Earth’s lower mantle

Elastic properties of high-pressure phases and implications for the temperature and mineralogy of Earth’s lower mantle