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We build a model to describe the net charges existing in the Sun and Earth. According to statistical mechanics, electrons on average move much faster than protons and neutrons at the same temperature. Electrons escape the Sun more easily than protons and neutrons, so the Sun becomes a charged star. We estimate the maximal net charges in the Sun by using statistical mechanics first. Then, we analyze the dynamical cycles between the positive and negative charged states. At a distance far away from the Sun, the effective net charges including the leaving protons and electrons are about 6.3 × 10 9 C with energies of 1 GeV initially. We also use another way based on the observations of the Earth's perihelion precession to estimate the minimum and maximum net charges between 1.15 × 10 8 C and 2.80 × 10 10 C in space from the Sun to Earth. The most charged particles from the Sun to the Earth are electrons, so both the Moon and Earth are impacted by them and very possibly have the same electricity. Next, we propose new physical mechanisms causing the slowdown of the Earth's spin and propose Coulomb's repulsive force resulting in the increasing distance between the Moon and Earth. As a result, it gives the net charges of 1.11 × 10 6 C surrounding the Earth and 8.29 × 10 3 C surrounding the Moon. Our estimations also correspond to early works. The charges surrounding the Sun and Earth cause the Earth to be long-term accelerated in the radial direction by Coulomb's force. Finally, using the effective net charges of the Sun and Earth, we calculate the increasing distance between 11.4 m and 19.4 m on average per century if the initial radial velocities of the Earth are in between 3.59 × 10 − 9 m / s and 6.12 × 10 − 9 m / s , which satisfies the observed reports. • A model describes the charges of the Sun and the force between the Sun and Earth. • The charged processes between two transient states are from negative to positive. • Both the Moon and Earth are impacted mostly by electrons from the Sun. • The negative charges of the Earth and Moon cause to exist Coulomb's repulsive force. • The Coulomb's force between the Sun and Earth can accelerate the Earth in the radial direction. [ABSTRACT FROM AUTHOR]

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The core‐mantle boundary (CMB) and the outermost core are dynamic and heterogeneous regions with time‐dependent flows. We examine two seismic raypaths, diffracted P and PKP precursors—both replete with scattering, with precisely repeating earthquakes. These earthquakes, occurring in the South Sandwich Islands, were recorded on the Yellowknife array in Canada, the Alice Springs array in Australia, and the Eilson Array in United States for the past 30 years. In all the most resolved cases, five for diffracted P and 19 for PKP precursors, we observe 1–2 Hz scattered waves that exactly repeat within the resolution of our study for more than 10 s. Although the absence of observable changes is unsurprising, it imposes constraints on potential temporal variations near the CMB. This suggests that any dynamic processes in this region might either be too subtle to detect, even with high‐frequency waves, or occur on different timescales. Plain Language Summary: Earthquakes generate waves that travel through the Earth's interior, revealing details about its structure. In this study, we examined how certain high‐frequency waves behave as they pass near the boundary between the Earth's core and mantle. By analyzing waves from repeating earthquakes, which have almost identical focal mechanism and locations, in the South Sandwich Islands, recorded by stations in Canada and Australia, we found no noticeable changes over time. This suggests that the core‐mantle boundary remains stable, at least within the time frame and sensitivity of our study. These findings help us better understand the dynamics of the Earth's deep interior and guide future research in this area. Key Points: We analyzed two high‐frequency seismic phases from repeating earthquakes to seek temporal changes near the core‐mantle boundary (CMB)No significant temporal changes were observed in the scattered waves recorded by seismic arrays in Canada and AustraliaThe absence of detectable changes constrains the dynamic and mineralogical processes at the CMB, and informs future, more sensitive studies [ABSTRACT FROM AUTHOR]

Sulfur (S) in the mantle is conventionally assumed to be exclusively stored in accessory sulfide phases, but recent work shows that the major silicate minerals that comprise >99% of the mantle could be capable of hosting trace amounts of S. Assessing the incorporation of trace S in nominally S-free mantle minerals and determining equilibrium S partitioning between these minerals and basaltic melt requires analyzing small experimental phases with low S contents. Here, we develop a protocol for EPMA analysis of the trace levels of S in silicate phases. We use a suite of natural and experimental basaltic glass primary and secondary standards with S contents ranging from 44 ppm to 1.5 wt%. The effects of beam current and counting time are assessed by applying currents ranging from 50 to 200 nA and total counting times between 200 and 300 s at 15 kV accelerating voltage. We find that the combination of 200 nA beam current with a 200 s counting time (80 s peak, 60 s each for upper and lower background, respectively) achieves precise yet cost-effective measurements of S down to a calculated detection limit of ~5 ppm and a blank-derived, effective detection limit of ~17 ppm. Close monitoring of the S peak intensity and position throughout the duration of each spot also shows that high currents and extended dwell times do not compromise the accuracy of measurements, and even low S contents of 44 ppm can be reproduced to within one standard deviation. Using our developed recipe, we analyzed a small suite of experimental clinopyroxenes (Cpx) and garnets (Gt) from assemblages of silicate partial melt + Cpx ± Gt ± sulfide, generated at 1.5 to 3.0 GPa and 1200 to 1300 °C. We find S contents of up to 71 ± 35 ppm in Cpx and 63 ± 28 ppm in Gt and calculate mineral-melt partition coefficients ( (D s min/melt) ) of up to 0.095 ± 0.064 and 0.110 ± 0.064 for D s Cpx/melt and D s Gt/melt , respectively. The sulfur capacity and mineral-partitioning for Cpx are in good agreement with SXRF measurements in a prior study by Callegaro et al. (2020), serving as an independent validation of our EPMA analytical protocol. [ABSTRACT FROM AUTHOR]

As human activities increase and environmental changes persist, increased ultraviolet B (UVB) radiation in aquatic ecosystems poses significant threats to aquatic life. This study, through transcriptomic analysis of the mantle tissue of Crassostrea gigas following UVB radiation exposure, identified and validated two key transcription factors, CgRunx1 and CgCBFβ. The highest expression levels of CgRunx1 and CgCBFβ in the mantle suggest their pivotal roles in this tissue. Co-immunoprecipitation experiments revealed that CgRunx1 and CgCBFβ could form heterodimers and interact with each other. Furthermore, this study assessed the impact of UVB radiation on the levels of reactive oxygen species of the C. gigas, speculating that CgRunx1, as a potential redox-sensitive transcription factor, might be regulated by intracellular ROS. Through screening and binding site prediction analysis of target genes, coupled with dual-luciferase reporter assays, we verified that CgRunx1 might participate in regulating the biomineralization and autophagy processes in C. gigas by activating the transcriptional expression of target genes Transport and Golgi organization 1 and V-type proton ATPase catalytic subunit A. These findings provide new insights into the molecular response mechanisms of the C. gigas to UVB radiation and lay an important foundation for studying the adaptive evolution of bivalves to environmental stress. [ABSTRACT FROM AUTHOR]

Nitrogen (N) is an essential element for life. Yet the processes of planet formation and early planetary evolution through which rocky planets like Earth obtained their atmospheric and surface nitrogen inventory are poorly understood. In order to understand the effect of early silicate differentiation of the rocky bodies on N inventory, here we study the elemental partitioning of N between the silicate minerals and melts. We conducted laboratory experiments using tholeiitic basalts and Fe + Si alloy mixtures at 1.5 – 4.0 GPa and 1300 to 1550 °C under graphite saturation at an oxygen fugacity range of IW–1.1 to IW–3.0. The experiments yielded an assemblage of Fe-rich alloy melt (am) + silicate melt (sm) + clinopyroxene (cpx) ± garnet (grt) ± orthopyroxene (opx) ± plagioclase (plag). Using electron microprobe, we determine that under the experimental conditions, N act as an incompatible element with D N c p x / s m (0.11 – 0.47) > D N p l a g / s m (0.41) > D N o p x / s m (0.25) > D N g r t / s m (0.06 – 0.21). The D N m i n e r a l / s m do not show any strong dependence on temperature, pressure, and melt composition. However, through comparison with previous estimates, it appears that with decreasing f O 2 , N becomes less incompatible. Under our experimental conditions of alloy melt-mineral equilibria, N behaves as a siderophile element (D N a m / m i n e r a l ranging from 4.1 to 60.6) with f O 2 playing the strongest control on D N a m / m i n e r a l . Our data suggest that under reducing conditions, in the early stages of a magma ocean (MO) and/or deeper mantle, silicate minerals would hold a non-negligible fraction of N as N becomes less atmophile and siderophile. Therefore, reduced parent bodies could also retain substantial N in the residual mantle during partial melting. The extraction of N from an internal MO or a solid planetary mantle is thus enhanced only as the system becomes more oxidizing, enriching the surficial reservoirs in N. Thus, Earth's N 2 -rich atmosphere may be intrinsically linked to its mantle oxidation, whereas other rocky planets of the Solar System, such as Mars and Mercury, may have retained a significant portion of their N inventory in nominally N-free mantle silicates through episodes of MO crystallization and mantle melting. [ABSTRACT FROM AUTHOR]

The results of a study of chilled glasses sampled during the 45th cruise of the R/V Professor Logachev at the top of the submarine volcano Puy des Folles are presented. The Puy des Folles volcano is located in the axial part of the rift valley of the Mid-Atlantic Ridge (MAR) at 20°31′ N. Unlike typical volcanic axial highs which usually does not exceed several hundred meters the summit of the Puy des Folles volcano is located a depth of 1950 m and rises 1800 m above the bottom of the rift valley. The data on geochemistry and isotope composition of chilled glasses examined allow us to come to a number of conclusions that expanded existing ideas about magmatic and tectonic processes conducted in the rift valley of the slow spreading ridges. Chilled glasses sampled at the top of the Puy des Folles volcano are originated from a very depleted melt formed by partial melting of the DM reservoir. Puy des Folles volcano was formed as result of the activity of a long-lived magma chamber located below the rift valley axis. It is possible that, in addition to the DM reservoir, a mantle source enriched in incompatible elements may have participated in the formation of the parental melts for the studied chilled glasses. A weak geochemical signal of contamination of the parental melt with a hydrothermal component in chilled glasses was established. Signs of stagnation in the spreading of the oceanic crust in the rift valley segment studied in this work have been established. [ABSTRACT FROM AUTHOR]

The Miocene Galatian Volcanic Province (GVP) is one of the largest volcanic provinces in central-western Anatolia, with an extent of ~ 8,900 km2. The volcanic activity is extended from 22.5 to 7.5 Ma. The volcanic compositions straddle the alkaline-subalkaline fields, from basic to acid compositions and mostly transitional to sodic affinity. Major oxides show good correlation with SiO2 indicating prolonged effects of fractional crystallization. Primitive mantle-normalized multi-element patterns indicate overall similarities among the different samples of the three geographic sectors, sharing strong negative anomalies in Nb–Ta–Ti, strong positive peaks at Cs and K, coupled with a common, albeit not always present, positive anomaly at Pb. Mineral-melt geothermobarometric estimates indicates ~1070–1235°C and ~7–19 kbar for melting conditions of basaltic compositions and ~1000–1150°C and ~3–12 kbar for andesitic-dacitic rocks. The absence of correlation between radiogenic isotopes and SiO2 and MgO is here interpreted as consequence of assimilation-fractional-crystalization processes involving lower continental crust as contaminant. The GVP parental magmas are generated from ~2% to 10% partial melting of a lherzolitic mantle with high spinel/garnet ratio based on intra-REE fractionation constraints. The subduction-related metasomatism inferred for the GVP mantle sources based on their chemistry is interpreted to be linked to the northward subduction of the northern branch of the Neo-Tethys slab. Successive slab retreat resulted in extension for the critical stress distribution through the Cyprus slab, favouring magma propagation for the GVP volcanic region. The eventual break-off of the slab after the continent-continent collision of Arabian and Eurasian plates could have caused a toroidal mantle flow, favouring the widely distributed 15–16 Ma alkaline magmatism in the eastern GVP, associated with passive hot asthenospheric upwelling imaged by teleseismic P-wave tomography. [ABSTRACT FROM AUTHOR]

The Earth's mantle transition zone has significant control on material flux between upper and lower mantle, thus constraining its properties is imperative to understand dynamic processes and circulation patterns. Global seismic data sets to study the transition zone typically display highly uneven spatial distribution. Therefore, complementary geometries are essential to improve knowledge of physical structures, thermochemistry, and impact on convection. Here, we present a new automated approach utilizing machine learning to analyze large seismic data sets, and derive high‐resolution maps of transition zone discontinuity properties. Seismic measurements from ScSScS precursors are integrated with mineralogical modeling to constrain thermochemistry of the western Pacific subduction zone. Our models map recent subduction patterns through the transition zone, indicating stagnation of slabs and accumulation of basalt at its base, and interaction between stagnant slabs and plumes. These results suggest that the thermochemical properties of upper mantle discontinuities can provide high‐resolution images of mantle circulation patterns. Plain Language Summary: Earth's upper mantle displays several discontinuous jumps in its physical properties, which result from changes in its mineral structure as pressure and temperature increase with depth. The major transitions near to 410 and 660 km depth are associated with physical changes that have significant influence on the flow of hot upwelling plumes and cold downgoing slabs. The depth and strength of the discontinuities depend on the local temperature and composition, and therefore constraining these properties can help to track mantle circulation patterns and better understand convection behavior. Global seismic data sets are highly uneven in spatial coverage, and therefore must be supplemented by data sets with different spatial sensitivity. Here, we present an automated approach based on machine learning to analyze seismic phases with such complementary geometry, and apply these techniques to investigate subduction zones beneath the western Pacific. We incorporate high‐resolution observations of the discontinuities with modeling from mineral physics, producing new models of temperature and composition in this region. The models track recent convection patterns through the transition zone, indicating ponding of slabs and plumes. These results suggest that the temperature and composition of the transition zone can be used to provide detailed maps of mantle circulation. Key Points: New data sets of ScSScS precursors beneath the western Pacific subduction zones are compiled and analyzed with machine learning methodsHigh‐resolution measurements of transition zone discontinuities and mineralogical modeling provide detailed maps of thermochemistryThermochemical models track recent mantle circulation patterns, indicating slab stagnation, basalt accumulation, and interaction with plumes [ABSTRACT FROM AUTHOR]

This paper answers a question of Usuba [Extendible cardinals and the mantle, Arch. Math. Logic 58(1–2) (2019) 71–75], establishing the optimality of the large cardinal assumption of his remarkable theorem that if there is an extendible cardinal, there is a minimum inner model from which the universe of sets can be obtained as a forcing extension. [ABSTRACT FROM AUTHOR]

Akimotoite, ilmenite-type MgSiO3 high-pressure polymorph can be stable in the lower-mantle transition zone along average mantle and subducting slab geotherms. Significant amounts of Al2O3 can be incorporated into the structure, having the pyrope (Mg3Al2Si3O12) composition. Previous studies have investigated the effect of Al2O3 on its crystal structure at nearly endmember compositions. In this study, we synthesized high-quality ilmenite-type Mg3Al2Si3O12 phase at 27 GPa and 1073 K by means of a Kawai-type multi-anvil press and refined the crystal structure at ambient conditions using a synchrotron X-ray diffraction data via the Rietveld method to examine the effect of Al2O3. The unit-cell lattice parameters were determined to be a = 4.7553(7) Å, c = 13.310(2) Å, and V = 260.66(6) Å3, with Z = 6 (hexagonal, R 3 ¯ ). The volume of the present phase was placed on the akimotoite-corundum endmember join. However, the refined structure showed a strong nonlinear behavior of the a- and c-axes, which can be explained by Al incorporation into the MgO6 and SiO6 octahedral sites, which are distinctly different each other. Ilmenite-type Mg3Al2Si3O12 phase may be found in shocked meteorites and can be a good indicator for shock conditions at relatively low temperatures of 1027–1127 K. [ABSTRACT FROM AUTHOR]

SUMMARY: Using forward mantle convection models starting at 140 Ma, and assimilating plate reconstructions as surface velocity boundary condition, we predict present-day mantle structure and compare them with tomography models, using geoid as an additional constraint. We explore a wide model parameter space, such as different values of Clapeyron slope and density change across 660 km, density and viscosity of the thermochemical piles at the core–mantle boundary (CMB), internal heat generation rate, and model initiation age. We also investigate the effects of different strengths of a weak layer below 660 km and weaker asthenosphere and slabs. Our results suggest that slab structures at different subduction zones are sensitive to the viscosity of the asthenosphere, strength of slabs, values of Clapeyron slope and the density and viscosity of the thermochemical piles, while different internal heat generation rates do not affect the slab structures. We find that with a moderately weak asthenosphere ($10^{20}$ Pa·s) and strong slabs, the predicted slab structures are consistent with the tomography models, and the observed geoid is also matched well. Moreover, our models successfully reproduce the degree-2 structure of the lower mantle beneath Africa and the Pacific, also known as Large Low Shear Velocity provinces (LLSVPs). A moderate Clapeyron slope of −2.5 MPa K−1 at 660 km aids in slab stagnation while higher values result in massive slab accumulation at that depth, ultimately leading to slab avalanches. We also find that the convective patterns in the thermal and thermochemical cases with slightly denser LLSVPs are similar, although the geoid amplitudes are lower for the latter. However, with more dense LLSVPs, the slabs cannot perturb them and no plumes are generated. Plumes arise as thermal instabilities from the edges of the LLSVPs, when cold and viscous slabs perturb them. While our predicted plume locations are consistent with the observed hotspot locations, matching the plume structures in tomography models is difficult. These plumes are essential in fitting the finer features of the observed geoid. In longer-duration models, more voluminous subducted material reaches the CMB, which tends to erode the LLSVPs significantly, and yields a poor fit to the observed geoid. Our results suggest that with the presence of a thin, moderately weak layer below 660 km, a slightly dense LLSVP, and Clapeyron slope of −2.5 MPa K−1, the velocity anomalies in seismic tomography and the long-wavelength geoid can be matched well. One of the limitations of our models is that the assimilated plate motion history may be too short to overcome arbitrary initial conditions effects. Also, assimilated true plate velocities in our models may not represent the true convective vigour of the Earth. [ABSTRACT FROM AUTHOR]

The compositional diversity of primitive arc basalts has long inspired questions regarding the drivers of magmatism in subduction zones, including the roles of decompression melting, mantle heterogeneity, and the amount and composition of slab‐derived materials. This contribution presents the volatile (H2O, Cl, and S), major, and trace element compositions of melt inclusions from basaltic magmas erupted at three volcanic centers in the Washington Cascades: Mount St. Helens (two basaltic tephras, 2.0–1.7 ka), Indian Heaven Volcanic Field (two <600 ka basaltic hyaloclastite tuffs), and Glacier Peak (late Pleistocene to Holocene basaltic tephra from Whitechuck and Indian Pass cones). Compositions corrected to be in equilibrium with mantle olivine display variability in Nb and trace element ratios indicative of mantle source variability that impressively spans nearly the entire range of arc magmas globally. All volcanic centers have magmas with H2O and Cl contributions from the downgoing plate that overlap with other Cascade Arc segments. Volatile abundances and trace element ratios support a model of melting of a highly variably mantle wedge driven by a subduction component of variably saline fluid and/or slab partial melt. Magmas from Glacier Peak in northern Washington have unusually high Th/Yb ratios that are similar to Lassen region basalts, indicating possible contributions of "subcreted" metasediments that geophysical data suggest are not present beneath central Oregon and southern Washington. This data set adds to the growing inventory of primitive magma volatile concentrations and provides insight into spatial distributions of mantle heterogeneity and the role of slab components in the petrogenesis of arc magmas. Key Points: The Washington Cascades sub‐arc mantle is remarkably heterogeneousVolatile contributions from the slab are identifiable across different magma types in the WA CascadesSlab fluids of variable salinity and slab partial melts, non‐uniquely, may contribute to subduction components along the entire arc [ABSTRACT FROM AUTHOR]

Fe isotope variations in rocky bodies reveal fundamental information about planetary evolution. However, experimental results have come to contradictory conclusions on the equilibrium Fe isotope fractionation between metal and silicate during core-mantle differentiation. Many different processes, including evaporation, core formation, partial melting and disproportion of mantle silicate, have been consequently proposed to explain the observed Fe isotope variations in rocky solar system bodies. Here we perform ab initio molecular dynamics simulations and find that the anharmonicity in iron strongly decreases the force constant of Fe at low pressures (<∼50 GPa), which even reverses the equilibrium Fe isotope fractionation between metal and silicate. We conclude that pyrolitic melt is always enriched in heavy Fe isotopes relative to liquid Fe-alloys, no matter what pressure. Therefore core-mantle differentiation will play a significant role in explaining the heavy Fe isotope compositions of the mantles of some rocky bodies (e.g., Earth, the ureilite parent body, and possibly the asteroid Vesta). As all previously proposed processes for Fe isotope fractionation can only enrich the mantle-derived rocks in heavy Fe isotopes, the near/sub-chondritic Fe isotope signatures of Mars and the aubrite parent body thus imply that iron sulfide enriched in light Fe isotopes may significantly contribute to the iron components of those meteoritic samples. [ABSTRACT FROM AUTHOR]

In this article we examine the effects of eclogitization of slab rocks on the subduction regime under a continent. Eclogitization of rocks in high-pressure metamorphic complexes occurs only in the areas of penetration of hydrous fluid. In the absence of hydrous fluid, the kinetic delay of eclogitization preserves low-density rocks under P‒T conditions of eclogite metamorphism, delaying the weighting of a slab and reducing the efficiency of the slab-pull mechanism, which contributes to steep subduction into the deep mantle. The results of numerical petrological–thermomechanical 2D modeling of subduction under a continent in a wide range of eclogitization parameters of oceanic crustal rocks (discrete eclogitization) are presented. The effects of a lower kinetic delay of eclogitization in a water-bearing basalt layer, compared to a drier underlying gabbro layer, have been tested. Based on the results of 112 numerical experiments with 7 variants of eclogitization ranges (400–650°C for basalt and 400–1000°C for gabbro) at different potential mantle temperatures (ΔT = 0–250°C, above the modern value), and steep, flat, and transitional subduction regimes were identified. The steep subduction regime occurs under modern conditions (ΔT = 0°C) with all ranges of eclogitization. Here, it is characterized by an increase in the angle of subduction of the slab as the plate descends, and above the boundary of the mantle transition zone there is a flattening and/or tucking of the slab. Subduction is accompanied by the formation of felsic and mafic volcanics and their plutonic analogues. At elevated mantle temperatures (ΔT ≥ 150°С) and discrete eclogitization over a wide range, the flat subduction regime is observed with periodic detachments of its steeper frontal eclogitized part. The flat subduction regime is accompanied by significant serpentinization of the mantle wedge and sporadic, scarce magmatism (from mafic to felsic), which occurs at a significant distance (≥500 km) from the trench. During the transition regime, which is also achieved in models with elevated mantle temperatures, a characteristic change occurs from flat to steep subduction, resulting in a stepped shape of the slab. As the kinetic shift of eclogitization increases, flat subduction develops. An increase in the thickness of the continental lithosphere from 80 to 150 km contributes to steep subduction, while the influence of the convergence rate (5–10 cm/year) is ambiguous. Discrete eclogitization of thickened oceanic crust and depletion of lithospheric mantle in the oceanic plate are the main drivers of flat subduction. In modern conditions, their influence becomes insignificant due to the decrease in thickness of oceanic crust and degree of depletion of the oceanic mantle lithosphere. As a result, less frequent flat movement of slabs is determined by other factors. [ABSTRACT FROM AUTHOR]

Giant clams obtain their nutrition from both filter-feeding and photosynthates produced by symbiotic zooxanthellae within their mantle tissue. The symbiotic partnerships between giant clam and zooxanthellae are critical for the health and survival of giant clams. Therefore, light/dark alternation plays a crucial role in influencing the growth performance and physiological change of the giant clam-zooxanthellae symbiosis in natural ecosystems. In this study, the rhythms of mantle surface area, physiological metabolic activity, and oxidative stress in the boring giant clam, Tridacna crocea, caused by two different light-dark cycles (7:00–19:00 light-on and 9:00–21:00 light-on, respectively) were investigated. The relative mantle surface area, net calcification rate and gross primary production significantly increased with the increase in light time, and the highest values were observed after 4–7 h of light exposure. The values of symbiosis Y (II) sharply increased when giant clams were transferred from dark to light conditions, and then slightly decreased to a low level until the next light/dark cycle. Dynamic changes of zooxanthellae density in the outer mantle were observed with two-peak values noted at 4 h after light-on and -off, respectively. The absorption of ammonium-nitrogen (negative values of ammonia metabolic rate) was observed when giant clams were exposed to light, and the rate reached its highest value after 10 h of light exposure. Rhythmic changes of oxidative stress related enzymes and antioxidant molecule were also detected in the inner and outer mantles. In detail, the highest values of SOD activity were observed around light-on time in both the inner and outer mantles, while the tendency of CAT activity was not the same in the inner and outer mantles; the GSH contents in the inner mantle were significantly higher than that in the outer mantle, and their values significantly increased with light exposure; the MDA concentrations from 5:00 to 14:00 were almost the same in both the inner and outer mantles, which were significantly higher than those at other sampling points. The rhythms of these detected behaviors and physiological responses were almost delayed with the delay of photocycle. This provides experimental support for the hypothesis that some behaviors and physiological responses of giant clams exhibit 24-h rhythms, which are affected by changes of light/dark alternation. [ABSTRACT FROM AUTHOR]

Geochronological (U-Pb zircon, ID-TIMS), isotope-geochemical (Nd, Sr, Pb), and geochemical studies of rocks of the Amanan and Amudzhikan intrusive complexes and volcanic rocks of the Ukurey Formation in the eastern part of the West Stanovoy superterrane of the Central Asian Orogenic Belt were performed. The assignment of granitoids of these complexes to high-potassium C-type adakites is substantiated. It is established that the studied rocks are cogenetic and can be ascribed to a single Amudzhikan volcano-plutonic association formed in the age range of 133 ± 1–128 ± 1 Ma. The igneous complexes of this association belong to the Stanovoy volcano-plutonic belt, which extends in the sublatitudinal direction from the Pacific Ocean inward the North Asian continent for more than 1000 km, subparallel to the Mongol-Okhotsk suture zone, and assembles the tectonic structures of the Dzhugdzhur-Stanovoy and West-Stanovoy superterranes. The formation of the Stanovoy Belt is related to the closure of the Mongolo-Okhotsk Ocean and the collision between North Asian and Sino-Korean continents at ~140 Ma. The subsequent collapse of the collisional orogen, which was accompanied by large-scale lithospheric extension and delamination of the lower part of the continental lithosphere, led to upwelling of asthenospheric mantle. This caused melting of the lithospheric mantle and continental crust and, as a consequence, the formation of both mafic (shoshonitic) melts and anatectic crustal melts of the adakite type. The mixing of these melts led to the formation of the parental magmas of the Amudzhikan magmatic association. The crustal component in the source was of heterogeneous nature and finally formed as a result of the Early Cretaceous collision event. It is characterized by the upper-crustal isotopic signatures: increased Rb/Sr and U/Pb ratios and a decreased Sm/Nd ratio in the source. The mantle component is represented by enriched lithospheric mantle of the Central Asian Orogenic Belt, the formation of which is associated with subduction processes and closure of the Mongol-Okhotsk paleoocean. Metasomatic transformation of the mantle with the introduction of melts and fluids with isotopic parameters of an EMII-type source or upper crust occurred at this stage. [ABSTRACT FROM AUTHOR]

Magmatic periodicity is recognized in continental arcs worldwide, but the mechanism responsible for punctuated arc magmatism is controversial. Continental arcs in the Trans‐Himalayan orogenic system display episodic magmatism and the most voluminous flare‐up in this system was in early Eocene during the transition from subduction to collision. The close association of the flare‐up with collision is intriguing. Our study employs zircon Lu‐Hf and bulk rock Sr‐Nd isotopes, along with mineral geochemistry, to track the melt sources of the Nymo intrusive complex and the role of mantle magma during the early Eocene flare‐up of the Gangdese arc, Tibet. The Nymo intrusive complex is composed of gabbronorite, diorite, quartz diorite, and granodiorite which define an arc‐related calc‐alkaline suite. Zircon U‐Pb ages reveal that the complex was emplaced between ~50–47 Ma. Zircon Hf isotopes yield εHf(t) values of 8.2–13.1, while whole‐rock Sr and Nd isotopes yield εNd(t) values of 2.7–6.5 indicative of magmatism dominated by melting of a juvenile mantle source with only minor crustal assimilation (~15%–25%) as indicated by assimilation and fractional crystallization modeling. Together with published data, the early Eocene magmatic flare‐up was likely triggered by slab breakoff of subducted oceanic lithosphere at depths shallower than the overriding plate. The early Eocene magmatic flare‐up may have contributed to crustal thickening of the Gangdese arc. This study provides important insights into the magmatic flare‐up and its significant role in the generation of large batholiths during the transition from subduction to collision. [ABSTRACT FROM AUTHOR]

The Mauléon basin is a world‐class example of hyperextended rift suture. The basin possesses key attributes of an optimal hydrogen target, namely mantle, at shallow depth with tectonic structures rooted into it. Natural H2 seepages have been recognized at the surface in the foothills. Yet distribution and quantification of serpentinization within the mantel piece representing the potential H2 source has not been addressed while this aspect is crucial to consider further exploration. We discuss these aspects using joint gravimetric and magnetic 2D forward modeling along two orthogonal transects. 2D forward modeling shows that serpentinization gradually increases from bottom (20 km depth) to top reaching a maximum amount of nearly 76% (8 km depth). The N‐S transect evidence that serpentinization fronts are northward inclined, suggesting a N‐S serpentinization gradient responsible for the long wavelength gravity and magnetic anomalies. This orientation matches that of detachment within the former hyperextended domain, which exhumed the mantle during the Cretaceous. The W‐E transect shows that serpentinization also increase toward the east reaching its maximum amount against the Barlanès lithospheric structure. The latter also coincides with the main short wavelength magnetic anomaly recognized in the basin. Forward geophysical modeling reveals that this anomaly could be linked to the presence, at shallow depth, of an alkaline magmatic body or a shallower piece of highly serpentinized subcontinental mantle both attesting for the paroxysm of the Cretaceous rifting phase. Finally, we propose a conceptual model of the H2 life cycle in the Mauléon basin and discuss the implications for H2 exploration. Key Points: We address the distribution of serpentinization in an inverted hyperextended rift system based on joint gravimetric and magnetic modelingThe mantle is gradually serpentinized on an overall thickness of around 15 km reaching a maximum amount of nearly 76%The mantle and the basement top are respectively in optimal thermal windows to generate H2 by serpentinization and trap it [ABSTRACT FROM AUTHOR]

Earth is a unique planet in the universe characterized by a stable crust and a dynamic internal environment, fostering intelligent life. Studying Earth not only aids in understanding our habitat but also helps uncover mysteries of other celestial bodies. Earth parameter data are essential for a comprehensive understanding of the planet. Here we compile and update key data on Earth's fundamental parameters, historical evolution, and the current geophysical parameters and geochemical compositions of its atmosphere, water, crust, mantle, and core. The data are sourced from a combination of historical records, satellite observations, and recent field studies, and have been validated using established geophysical and geochemical methodologies. We specifically examine the elemental compositions of various Earth layers and offer recommended values for certain datasets, aiming at easier accessing fundamental Earth data, thereby facilitating deeper exploration of Earth sciences.

Abstract The core‐mantle boundary (CMB) and the outermost core are dynamic and heterogeneous regions with time‐dependent flows. We examine two seismic raypaths, diffracted P and PKP precursors—both replete with scattering, with precisely repeating earthquakes. These earthquakes, occurring in the South Sandwich Islands, were recorded on the Yellowknife array in Canada, the Alice Springs array in Australia, and the Eilson Array in United States for the past 30 years. In all the most resolved cases, five for diffracted P and 19 for PKP precursors, we observe 1–2 Hz scattered waves that exactly repeat within the resolution of our study for more than 10 s. Although the absence of observable changes is unsurprising, it imposes constraints on potential temporal variations near the CMB. This suggests that any dynamic processes in this region might either be too subtle to detect, even with high‐frequency waves, or occur on different timescales.

The mineralogy of planetary mantles formed under reducing conditions, as documented in the inner regions of the solar system, is not well constrained. We present thermodynamic models of mineral assemblages that would constitute the mantles of exo‐Mercuries. We investigated reduced materials such as enstatite chondrites, CH, and CB chondrites, and aubrites, as precursor bulk compositions in phase equilibrium modeling. The resulting isochemical phase diagram sections indicate that dominant phases in these reduced mantles would be pyroxenes rather than olivine, contrasting with the olivine‐rich mantles found within Earth, Mars, and Venus. The pyroxene abundances in the modeled mantles assemblages depend on the silica content shown by precursor materials. The silica abundance in the mantle is closely related to Si abundance in the core, particularly in reduced environments. In addition, we propose that pyroxene‐rich mantles exhibit more vigorous convective and tectonic activity than olivine‐rich mantles, given that pyroxene‐rich mantles would have lower viscosity and a lower solidus temperature (Ts). Plain Language Summary: Mineral assemblages that constitute the mantles of reduced exoplanets, such as those formed in the inner regions of stellar nebulae, have been scarcely investigated. We propose that these exoplanets share several physical and chemical properties with planet Mercury in our Solar System, as they formed in a similar geochemical environment. In order to outline the minerals constituting these mantles, we take in account all the chemical compositions previously proposed to match Mercury's observed characteristics. These compositions are extrapolated from several classes of meteorites, among the most pristine materials currently known and best candidates as "building blocks" of planetary objects. We, then use the well‐established thermodynamic code Perple_X to predict the stable minerals at pressure and temperature ranges assumed for these exoplanets' interiors. We find that silicate mantles of exoplanets located in inner regions of nebulae are dominated by pyroxene group minerals, rather than olivine, as in the Earth's mantle. This results in different rheological (e.g., viscosity) and physical properties (e.g., melting behavior) for these reduced exoplanets, with significant implications for their mantle dynamics and evolution over time. Key Points: The predicted mantle mineralogy in sub‐Earths and Mercury‐sized exoplanets includes pyroxenes, olivine, garnet, and silica polymorphsFive different meteorites have been chosen as precursor materials to model the rocky mantle, belonging to CH, CB, EN, and aubrite groupsA pyroxene‐rich mantle shows different chemical and physical properties, affecting exo‐Mercuries' internal structures and their evolution [ABSTRACT FROM AUTHOR]

Shergottite meteorites, classified as depleted, intermediate, or enriched based on incompatible trace elements and specific radiogenic isotope compositions (Sr, Nd, and Hf isotope ratios), point to multiple Martian mantle source regions. The oxygen fugacity (f O 2) of these mantle regions, determined from early crystallizing minerals using the olivine-pyroxene-spinel oxybarometer, appears to correlate with incompatible trace element enrichment and isotope compositions. However, values derived from the vanadium-in-olivine oxybarometer challenge this correlation, hinting at potential biases in oxybarometry or complexities in the redox conditions of the Martian mantle. By analyzing the intermediate shergottite Northwest Africa (NWA) 11043 with various oxybarometers, this study deduced its origin from a reduced mantle source, with an average f O 2 value of −0.77 ± 0.35 relative to the iron-wüstite (IW) buffer. Notably, these values coincide with those of depleted shergottites, which represent the depleted Martian mantle region. This redox similarity between intermediate and depleted shergottites contrasts with earlier notions that postulated intermediate shergottites as a mix of depleted and enriched mantle derivatives. Moreover, intermediate shergottites such as NWA 11043, Elephant Moraine (EETA) 79001A, and Allan Hills (ALH) 77005 display 176Hf/177Hf values akin to those of depleted shergottites, suggesting that intermediate mantle components can be separated from the depleted mantle source at approximately 2.2 Ga based on model age calculations. Therefore, there presents a consistent redox state between mantle magma sources of both intermediate and depleted shergottites since the Hesperian period, while enriched shergottites lean toward more oxidized conditions past source formation. This study prompts a reassessment of conventional theories, emphasizing the nuanced redox evolution of the Martian mantle across distinct mantle source regions and underscoring the complexity of the redox evolution of the Martian mantle. The emergence of chemically diverse mantle reservoirs might predominantly arise from early magma ocean differentiation processes, albeit with inherent oxidation nuances. The differences in f O 2 observed between intermediate and depleted shergottites underscore the need for more in-depth studies to decipher Martian mantle differentiation and evolution. [ABSTRACT FROM AUTHOR]

The Archean–Proterozoic transition in the Earth's history is marked by significant changes in the mantle dynamics and temperature regimes. A notable consequence is the disappearance of Al-depleted komatiites in the Late Archean and an almost complete absence of Archean-typical peridotitic komatiites since the Proterozoic. This work presents a study of the 2.41 Ga komatiitic basalts from the Vetrenyi Belt, dating back to the early Proterozoic. Unique data on the compositions of olivine and chromite, as well as on the crystallization temperatures based on Al-in-olivine geothermometry for komatiitic basalts from the Vetrenyi Belt are provided. The temperatures of the earliest stages of crystallization were approximately 1240 ± 25°C, which indicates the occurrence of water in the melt and is consistent with measured water contents of 0.4 ± 0.2 wt % H2O in the melt inclusions. However, during crystallization, the komatiitic basalt melt underwent degassing, resulting in mass crystallization of the system and a temperature rise by ~20°C due to the release of the latent heat of crystallization. The degassing of water from the melt suggests crystallization under surface conditions. [ABSTRACT FROM AUTHOR]

The 17.44 Ma Walgidee Hills lamproite in the West Kimberley province of Western Australia is the type locality for several K-, Ba- and Ti-rich minerals characteristic of lamproites and, at 490 ha, the largest known lamproite. The Walgidee Hills pipe comprises a thin sequence of tuffs and breccia formed by explosive eruptions that excavated a large shallow crater that was infilled by lamproite magma which cooled and crystallised in situ. The lamproite is zoned in grain size, mineralogy, and mineral and rock composition from porphyritic olivine lamproite at the margin through medium-grained lamproite comprised of olivine (altered), titanian phlogopite, diopside, leucite (altered) and titanian potassic richterite to coarse gained lamproite rich in potassic richterite, priderite, jeppeite, perovskite, apatite, wadeite and noonkanbahite at the centre of the body. Compositional zoning is evident across the lamproite in phlogopite (to lower Mg and Al, higher Fe), potassic richterite (to higher Fe and Na, lower Ti), priderite (to lower Cr) and perovskite (to lower Cr and Fe, higher Na, Sr, Y, Nb, U, REE). The Walgidee Hills lamproite is ultrapotassic and ranges from olivine lamproite (up to ~21 wt % MgO, ~800 μg/g Ni, ~4 wt % K2O) to sanidine/leucite-rich lamproite (~7 wt % MgO, ≤100 μg/g Ni, ~8 wt % K2O) at the centre of the pipe. The lamproite has low Al2O3, total Fe, Na2O and CaO (except for intensely carbonate-veined rocks at the centre) and is highly enriched in TiO2 (3–6.5 wt %), Ba, Rb, Sr, Zr and LREE (LaN = 150–520 x primitive mantle). A transect and geochemical contours show MgO, Ni and Cr contents decrease and P, K, Ti, Fe, Rb, Sr, Y, Zr, Nb, REE, Hf, Pb, Th and U abundances increase inwards to the most evolved rocks at the centre of the pipe, consistent with fractionation by inwards in situ crystallisation. The parent magma is estimated from the composition of the porphyritic olivine lamproite at the margins of the pipe to have ~16 ± 1 wt % MgO, ~600 μg/g Ni, ~6 wt % K2O with La/Yb ~ 150. Modelling suggests that the most MgO-rich lamproites result from entrainment of ~15–20 wt % mantle olivine in the parent magma. Cooling of the magma resulted in fractional crystallisation of olivine and in situ crystallisation with the evolved coarse-grained lamproites at the centre of the pipe crystallised from residual magma enriched in the more incompatible elements. Mantle xenocrysts include abundant Cr–Al spinel, chrome diopside, chrome pyrope, and rare diamond. Thermobarometry on the Cr diopside xenocrysts defines a cold paleogeotherm of ~38 mW/m2 and a thick lithosphere (~235 km) extending from the Kimberley craton. Many of the Cr diopsides from the deeper lithospheric mantle are enriched in K, Ba and LREE and these, and the Ti-rich spinel xenocrysts, are inferred to be derived from metasomatised mantle peridotite. The enriched trace element and Sr–Nd–Pb isotopic signatures of the Walgidee Hills lamproite suggest derivation from or extensive incorporation of ancient formerly depleted lithospheric mantle that has undergone metasomatism and long term (≥2 Ga) geochemical enrichment including by melts from Paleoproterozoic subducted crust. [ABSTRACT FROM AUTHOR]

Rare-Earth Elements (REE) are key geochemical tracers of crust–mantle differentiation, but there are few direct data on REE-rich minerals in mantle rocks. Here, we report the combined petrography and comprehensive chemical and isotopic characterization of three coesite- and kyanite-bearing eclogite xenoliths from the Udachnaya kimberlite pipe (Siberian craton), which are unusual in that two xenoliths (one with diamond and graphite) contain discrete, idiomorphic crystals of allanite at the grain boundaries of garnet and omphacite. Another xenolith contains allanite as part of a complex aggregate of calcite, apatite, barite, and celestine hosted by serpentine, which is a low-temperature secondary minerals likely result from metasomatic reaction at shallower depths during the transport of eclogite by the erupting kimberlite melt. The bulk rock composition reconstructed from the trace element composition of garnet and omphacite show marked depletion in LREE, precluding equilibration with kimberlite melt, whereas the measured bulk compositions show chondrite-normalized REE patterns with conspicuous depletions of Ce–Pr–Nd relative to La and Sm. The presence of 0.005 to 0.008 wt % of allanite, texturally and chemically out of equilibrium with the rock-forming minerals, allows balancing the LREE and Sm–Nd budget of the rock, whereas Th and U require additional hosts. This not only highlights the utility of measuring bulk eclogite xenoliths in bringing this unusual component to light, but also demonstrates that the long-known incompatible element enrichment in bulk eclogites reflects the deposition of discrete phases rather than merely bulk kimberlite melt addition. Although allanite is stable in metabasalts at the pressure–temperature conditions of 1025°C to 1080°C and 3.6 to 4.8 GPa recorded by the eclogite xenoliths, its association with Ba-Sr minerals suggests its formation via reaction of the host eclogites with kimberlite melt. This is supported by the similarity in 143Nd/144Nd ratios between bulk eclogite (0.51227–0.51249) and the host kimberlite at eruption, whereas clinopyroxene in part retains unradiogenic Sr (87Sr/86Sr = 0.70205 ± 0.00011) related to ancient depletion. The discovery of allanite in the Udachnaya eclogites demonstrates that this REE mineral can form when omphacite and grossular-rich garnet in eclogite breakdown in contact with REE- and alkali-rich carbonatite/kimberlite melt, and may be more common than hitherto recognized. Crystallization of allanite in the cratonic mantle eclogite reservoir may also help explain the difference in LREE abundances between the more strongly enriched carbonatite/kimberlite at depth and the final erupted product. It is likely that allanite is overlooked at eclogites xenoliths, while it is common accessory mineral, hosting REE in orogenic UHP/HP eclogites. Further studies are required to deciphered the peculiarities in metamorphic history recorded in eclogites xenoliths and orogenic eclogites, as well as the differences ancient (Archean/Proterozoic) and Phanerozoic subduction processes. [ABSTRACT FROM AUTHOR]

Each of the halogens constrains a different aspect of volatile cycling in the solid Earth. F is moderately incompatible in the mantle and has a low mobility at Earth's surface, meaning that it is preferentially retained in the mantle and continental crust. In contrast, Cl, Br, and I are strongly incompatible and highly soluble. Chloride is the dominant anion in seawater and many geofluids and a major component of evaporite minerals. Br and I are essential for life and significantly incorporated into organic matter that accumulates in marine sediments. Surficial fluids circulated into continental and oceanic crust incorporate surface-derived halogens into alteration minerals. As a result, subducting slabs and arc lavas are weakly enriched in F and strongly enriched in Cl, Br, and I. Subduction has maintained mantle Cl and Br concentrations at relatively constant levels since Earth's early differentiation, but mantle I/Cl has decreased over time. Halogen abundances on the early Earth were affected by I partitioning into Earth's core and possible loss of hydrophilic Cl, Br, and I in an early formed ocean. Halogens are powerful tracers of subduction zone processes on the modern Earth, with Cl, Br, and I having a dominantly subducted origin in Earth's mantle. The deep subduction cycles of Cl, Br, and I are more similar to that of H2O than they are to F, but the geochemical cycle of each halogen differs in detail. Halogen abundance ratios and stable isotope ratios vary systematically in Earth's surface reservoirs, meaning that halogens are powerful tracers of geological fluids and melts. [ABSTRACT FROM AUTHOR]

The general subject of this article deals with the term salt. Salt deposits usually contain chlorides, sulphates/gypsum, borates, carbonates, etc., that are seemingly part of the same system. Even though this article mainly presents data and observations on chlorides, which are not easily explained by the present paradigm, it should also prove relevant for the formation of sulphates and other types of salts observed in major salt deposits. The paradigm explaining large salt deposits rests on two pillars governing salt formation and salt deformation. Salt formation is thought to occur vis solar evaporation of seawater in restricted basins. Salt deformation and forming of salt diapirs is thought to occur due to gravity-induced movements. Our review presents peer-reviewed and published data and observations from different authors within different disciplines that challenge the present evaporite paradigm. The current theory/paradigm rests on numerous observations and interpretations in support of it. Adding more observational interpretations in support of the paradigm will not nullify even one observation that contradicts or remains unexplained by the theory. The contradicting evidence must be explained within the present paradigm for it to survive. Significant observations of and within salt deposits are presented, as well as visual and geophysical observations of salinity in crusts and mantles in relevant tectonic settings. In our view, the omnipresent salinity observed in the subsurface needs to be understood and included in the description of a new salt formation mechanism in order to fully explain all features presented herein. [ABSTRACT FROM AUTHOR]

The molybdenum (Mo) isotope system is pivotal in reconstructing marine redox changes throughout Earth's history and has emerged as a promising tracer for igneous and metamorphic processes. Understanding its composition and variation across major geochemical reservoirs is essential for its application in investigating high-temperature processes. However, there is debate regarding the δ98/95 Mo value of the Earth's mantle, with estimates ranging from sub-chondritic to super-chondritic values. Recent analyses of global mid-ocean ridge basalt (MORB) glasses revealed significant δ98/95Mo variations attributed to mantle heterogeneity, proposing a two-component mixing model to explain the observed variation. Complementary studies confirmed the sub-chondritic δ98/95Mo of the depleted upper mantle, suggesting remixing of subduction-modified oceanic crust as a plausible mechanism. These findings underscore the role of Mo isotopes as effective tracers for understanding dynamic processes associated with mantle-crustal recycling. [ABSTRACT FROM AUTHOR]

Abstract The compositional diversity of primitive arc basalts has long inspired questions regarding the drivers of magmatism in subduction zones, including the roles of decompression melting, mantle heterogeneity, and the amount and composition of slab‐derived materials. This contribution presents the volatile (H2O, Cl, and S), major, and trace element compositions of melt inclusions from basaltic magmas erupted at three volcanic centers in the Washington Cascades: Mount St. Helens (two basaltic tephras, 2.0–1.7 ka), Indian Heaven Volcanic Field (two

Minerals from > 200 mantle xenoliths from Komsomolskaya kimberlite pipe were studied by electron microprobe and LA-ICP-MS. They are metasomatised garnet and spinel peridotites containing phlogopite, amphibole and ilmenite with garnets (up to 12.5 wt% Cr2O3) and clinopyroxenes (up to 5 wt% Na2O) or rarer Fe-pyroxenites and A, B, C eclogites.Thermobarometry indicates that the lithospheric mantle beneath the Komsomolskaya pipe is layered. Heated porphyroclastic, deformed peridotites at the lithosphere base (7–6 GPa) are enriched in Fe. The cold group at 6.0–5.5 GPa (34 mW/m2) are depleted peridotites with sub-Ca garnets. Cpx-fertilized varieties belong to the middle part of the mantle section. Amphiboles range from Cr-hornblendes to edenites (2–6 GPa), showing K-Ti enrichment. Picroilmenites yield two pressure intervals from 6.5 to 5.0 GPa and from 5.0 to 4.0 GPa, forming two differentiation branches. Eclogites mainly occur in the lower part of the section with a peak at pressures of 4–6 GPa.Trace elements of melts that formed harzburgitic garnets-pyroxenes refer to oceanic MORB like melt interaction with peridotites. The sub-calcic S-type garnets are similar to subduction-related melts (S-type REE) with troughs in HFSE. Adakite-like hybrid metasomatism formed Na, Al-rich pyroxenes with peaks in Sr and HFSE. K-bearing pyroxenes and amphiboles refer to shoshonitic metasomatism. Trace elements for Cpx of re-fertilized mantle peridotites reveal high LREE, Nb-Ta troughs and peaks in Zr, Th, Sr, U. They are reacted to carbonatite –alkaline melts. Protokimberlite (essentially carbonatitic) interaction produced HFSE-enrichment. Type B eclogites show more subduction-related features with HFSE troughs while type A eclogites are closer to hybrid and peridotitic signatures. We suggest six types of major metasomatic agents. The 40Ar/39Ar ages of phlogopites vary in the 440–690 Ma range, with some at 1.6 Ga, suggesting multistage metasomatism.

This study proposes a new model operation for an intermediate thermal storage (ITS) tank for solar water heater system. It combines passive-charge active-discharge (PCAD) in a single storage tank, potentially reducing the number of components of the system and improving the net energy balance. The charge process is done by heating the storage material using an electric heater, which is also suitable for direct photovoltaic heating. The temperature profile of stabilized storage material in this stage shows a close plateau line in the solid-liquid transition, indicating a steady phase transition takes place. It minimizes the temperature deviation between the solid/liquid region, which is advantageous for determining the operation protocol. For the discharge process, the working fluid circulates from the mantle side and continues to the inner side of the tank, resulting in two-consecutive heating. It allows the fluid to harness the stored heat up to 72.8%. It is also achieved by the stabilized storage material, which has a better solidification mechanism. Thus, the proposed PCAD tank is able to meet the criteria of an ITS tank, which requires energy exchange during the charge/discharge stage. The finding demonstrates that a simplification of the ITS tank is achievable. The implication of the finding can be used as a fundamental basis for developing new solar water heating systems, including for direct charge operation using photovoltaic-heating systems where the heat is taken as alternative energy storage instead of electricity.

The article presents a study of the Earth’s crust and upper mantle in the Pechenga ore region, as well as areas adjacent to it in the northwestern part of the Kola region. Applying the receiver function technique to data acquired by three broadband seismic stations, we obtained one-dimensional seismic velocity distribution models to a depth of 300 km. The stations are located in the northern parts of Finland and Norway, as well as in the Pechenga region of the Russian Federation. Despite the stations being in relatively close proximity (within 100 km of each other), the velocity models turned out to be significantly different, which indicates structural discontinuity within the lithosphere. Thus, Finland station data set revealed a gradient crust-mantle transition, which is not present in the other two models. At depths of about 150 km, a low-velocity zone was discovered, associated with mid-lithospheric discontinuity, which was not found beneath the Pechenga ore region. Furthermore, the crustal structure of the Pechenga region has an anomalously high Vp/Vs ratio to a depth of about 20 km. Considering the fact that the Pechenga (Nikel) seismic station was installed in close proximity to major copper-nickel deposits, this anomaly can be interpreted as a relic of Proterozoic plume activity.

Abstract Water is transported into the deep mantle by subducting slabs, playing important roles in mantle dynamics and evolution. An aluminous hydrous mineral, phase δ with a main component of AlOOH, has been considered an important water carrier in the lower mantle. Recent studies reported that SiO2 stishovite can accommodate weight percent levels of water, indicating another important water carrier in the lower mantle. However, which mineral can mainly carry water is not clear yet. Recent hydrous phase relation studies reported that stishovite is depleted in alumina when coexisting with hydrous phase δ, in which water content of stishovite was not investigated. In this study, we investigated hydrogen partitioning between stishovite and hydrous phase δ at 24–28 GPa and 1000–1200 °C by means of Kawai-type multi-anvil press in combination with Fourier-transform infrared spectroscopy at ambient conditions on recovered samples. Fourier-transform infrared spectra of recovered stishovites showed that water contents of stishovite coexisting with hydrous phase δ were limited to up to ~ 500 ppm. This indicates that coexisting hydrous phase δ causes not only depletion in alumina but also in hydrogen in stishovite and therefore mainly transports water in a cold subducting slab. Once hydrous phase δ becomes thermally unstable, alumina and water contents in silica minerals are increased by the chemical reaction between SiO2 and AlOOH, and aluminous silica minerals such as stishovite and CaCl2-type phase will be a main water carrier in the lower mantle. Presence of small-scale seismic scatterers observed around 1900 km depth, which was considered to be caused by a transition from almost pure SiO2 stishovite to CaCl2-type phase, might also be able to be explained by the phase transition of stishovite coexisting with hydrous phase δ.

The geophysical technique of magnetotellurics (MT) was first described in 1953 and the associated technique of geomagnetic depth sounding (GDS) in 1959. Both methodologies have had a long history in Australia both for academic research and resource exploration. Since the early 1990s with advances in digital data storage, 2D inversion codes and 3D inversion codes from the 2010s, there has been a rapid increase in the number of MT surveys across Australia. Regional MT programs around Australia and since 2013 the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) have steadily mapped the 3D resistivity of the Australian continent. To complement the regional AusLAMP MT sites numerous additional transects, and broadband MT grids have been deployed providing remarkable new insights into the tectonic evolution of the Australian lithosphere and provide the link to crustal mineral resources. In this special edition, ten papers explore different aspects of MT research in Australia over the last decade. [ABSTRACT FROM AUTHOR]

The shell of bivalves acts as structural support, defence against predators, stressors, and maintenance of homeostasis. Haemocytes and mantle epithelial cells participate in shell formation. Mantle epithelial cells produce the organic matrix of the shell and are associated with biomineralization because of their proximity to the shell surface and ability to maintain shell deposition ex vivo. Haemocytes play an immunological role and are involved in Ca2+ and CO32- intracellular transport implicated in shell mineralization. This study aims to evaluate the expression of molecules that play key roles in internal defence and the nervous system, in epithelial cells and haemocytes of the outer mantle margin of two species of bivalves, Polititapes aureus Gmelin, 1791 and Cerastoderma glaucum Bruguière, 1789, to highlight their collaborative role in shell formation. Our data show for the first time the presence of serotonin/S100 protein, and TLR2/iNOS colocalization in the haemocytes and mantle epithelial cells of P. aureus and C. glaucum , suggesting that the mantle cells perform their canonical role of sensory and biomineralizing activity, while the haemocytes perform their typical immune function, and their collaboration in shell formation, providing new information on cellular interactions in shell formation and giving more details for taxonomical studies. [ABSTRACT FROM AUTHOR]

Synthesized polycrystalline samples composed of enstatite and olivine with different volumetric ratios were deformed in compression under anhydrous conditions in a Paterson gas‐medium apparatus at 1150–1300°C, an oxygen fugacity buffered at Ni/NiO, and confining pressures of 300 or 450 MPa (protoenstatite or orthoenstatite fields). Mechanical data suggest a transition from diffusion to dislocation creep with increasing differential stress for all compositions. Microstructural analyses by optical and scanning electron microscopy reveal well‐mixed aggregates and homogeneous deformation. Crystallographic preferred orientations measured by electron backscatter diffraction are consistent with activation of the slip systems (010)[100] and (010)[001] for olivine and (100)[001] and (010)[001] for enstatite, as expected at these conditions. Nonlinear least‐squares fitting to the full data set from each experiment allowed the determination of dislocation creep flow laws for the different mixtures. The stress exponent is 3.5 for all compositions, and the apparent activation energies increase slightly as a function of enstatite volume fraction. Within the limits of experimental uncertainties, all two‐phase aggregates have strengths that lie between the uniform strain rate (Taylor) and the uniform stress (Sachs) bounds calculated using the dislocation creep flow laws for olivine and enstatite. Calculation of the Taylor and Sachs bounds at strain rate and temperature conditions expected in nature (but not extrapolating in pressure) indicates that using the dislocation creep flow law for monomineralic olivine aggregates provides a good estimate of the viscosity of olivine‐orthopyroxene rocks deforming by dislocation creep in the deeper lithosphere and asthenosphere. Plain Language Summary: The rheology of Earth's upper mantle is generally modeled using mechanical flow laws determined for aggregates composed only of olivine minerals, in spite of the polyphase nature of mantle rocks. In this study, we investigated the effect of phase volume proportions on the high‐temperature deformation properties of aggregates composed of the two most abundant minerals in the upper mantle, olivine and enstatite. The samples were deformed under dry conditions in triaxial compression at 1150–1300°C, under oxygen fugacity fixed at the Ni/NiO solid buffer, and confining pressures of 300 or 450 MPa, at conditions where enstatite has two different crystallographic structures. At both pressures, in the dislocation creep regime, where deformation occurs mostly by the motion of dislocations along slip planes within mineral grains, the strengths of all the two‐phase mixtures lie between the uniform strain rate and the uniform stress bounds, which assume iso‐strain and iso‐stress conditions, respectively, in all the grains comprising each aggregate. Extrapolating these bounds to temperatures and strain rates expected in nature indicates that the viscosity of mantle rocks can be modeled adequately with the dislocation creep flow law for olivine. Key Points: Polycrystalline samples of enstatite and olivine with different volumetric ratios were deformed in compression at high temperatureAll two‐phase aggregates have strengths in dislocation creep that lie between the uniform stress and uniform strain rate boundsIn dislocation creep the flow law for olivine provides a good estimate of the viscosity of olivine‐pyroxene rocks under natural conditions [ABSTRACT FROM AUTHOR]

The ectomycorrhizal (EcM) roots of Cedrus deodara associated with a unique hypogeous EcM fungus—Rhizopogon himalayensis is meticulously characterized and comprehensively described based on well‐established standard morphological and anatomical features. The mycobiont—R. himalayensis was found organically associated with the roots of C. deodara. The EcM morphotypes are distinguished by differences in the shape and color of the roots, type of ramification, surface texture, type of mantle, as well as different chemical reactions. All the examined morphotypes were having similar mycorrhizal system and anatomically (Mantle and Hartig net) no disparities were seen, that is, nonsignificant (p > 0.05) variations were observed. The majority of mycorrhizal systems were irregularly pinnate, dichotomous type with 0–1 order of ramification and occasional coralloid type. Mantle surface was densely cottony to loosely wooly. The outer and inner mantles were H & Q type. Hartig net was a complex net‐like structure with uniseriate to mutiseriate type of hyphal cell arrangement. Rhizomorph were smooth and round, consistently growing along roots. Moreover, extraradical hyphae were hyaline, septate, and without clamp connections. Sclerotia and cystidia were absent. Our findings will contribute to the biology of ectomycorrhizae associated with primitive and economically valuable conifers, thriving in the face of shifting environmental conditions in the northwestern Himalayas. [ABSTRACT FROM AUTHOR]

Purpose. Mantle density models are key tools for understanding the fundamental geological and physical processes occurring within the Earth and are essential to our scientific and applied understanding of the planet. Methodology. The tasks were solved by a complex research method, including analysis and generalization of literary and patent sources, analytical, experimental studies, using computer and mathematical modelling methods. Findings. One-dimensional models simplify the mantle density distribution by assuming that it is uniform only in the vertical direction. This limitation does not allow for horizontal variations in mantle density, which may be important on a regional scale. 3D models are more complex and require more data and computational resources, so their use may be limited. In this study, we present a quasi-three-dimensional model of mantle density beneath the Ukrainian Shield. This 3D model is obtained using a basic set of one-dimensional seismic tomographic velocity models calculated for 21 mantle domains in the depth range from 50 to 2,600 km. The process of converting the P-wave velocity model into a density model includes the following stages: 1) determining seismic boundaries in the mantle based on P-wave velocity curves for each mantle domain; 2) creating a synthetic mantle model beneath the Ukrainian Shield for the P,S-wave velocity curves; 3) solving the Adams-Williamson equation for each domain, considering polynomial corrections to extract heterogeneities during its solution; 4) analysing existing models by comparing the calculated gravitational potential at the central point of the Ukrainian Shield as the standard reference for selecting one of 5 reference models. Here, we focus on the final stages of constructing the mantle density model by: 1) balancing the mass of the upper and lower mantle for each domain when determining density using the Adams-Williamson equation and introducing polynomial corrections; 2) calculating densities for each of the 21 mantle domains and their 3D integration. Originality. The obtained mantle-density model of the Ukrainian Shield aligns well with the division of the mantle into three main layers: lithosphere, upper mantle, and lower mantle. Each of the mantle’s structural layers has its representation pattern in density heterogeneities. Anomalies of decreased density in the lithosphere of the Ukrainian Shield correlate with thermal anomalies, whereas anomalies of increased density correspond to tectonic zones dividing its megablocks. Practical value. Regions of increased density gradient are associated with mantle thrust faults, which in some cases can be boundaries between different petrological formations and serve as channels for magma ascent into the Earth’s crust at certain stages of geological development of the Ukrainian shield and, in turn, be sources of minerals. [ABSTRACT FROM AUTHOR]

An evolution strategy-type heuristic simulation tool was developed to model the inverse problem of partial melting. The complexity of such a problem is expressed by the non-uniqueness of solution and the high number of variables it could have: 1 denoting the degree of freedom + m from the number of minerals of the rock + q from the number of rare earth elements. This motivated us to redefine the problem as an optimization one deriving an objective function from the batch equation to model the source composition and the partial melting degree from the chemistry of near-primary liquids. Then, we optimize the inverse modeling by using a heuristic approach, namely, Evolution Strategy. In the search algorithm structure it was considered: (a) the geochemical system constraints, (b) an initialization step, and (c) a procedure of mutation and heuristic individual selection. The heuristic simulation was successfully applied in four study cases, as mineralogical and rare earth element (REE) composition of known peridotitic sources. The partial melting conditions were reproduced with a deviation ≤ 10 - 6 in a reasonably practical time ( ∼ 2 hours), in the search for 1000 solutions, by using a desktop computer. Moreover, our technique provides several efficient solutions, due to non-uniqueness, which allows to explore different scenarios when when a priori knowledge is missing. On the other hand, the algorithm is also able to approach the original melt when knowing only n + 1 variables of it. The flexibility in the construction of our complete methodology, joined to the successfully results and the possibility to apply it to any trace element, suggests its extension to similar magmatic processes. [ABSTRACT FROM AUTHOR]

To investigate the impact of heavy metals on the physiology of aquatic organisms, previous studies have focused on selected biomarker measurements in samples. However, most studies do not take into account toxicity effects on both males and females. The present paper aims to examine the effect of sex on the detoxification response using metallothioneins (MTs), a biomarker of metallic contamination. MTs were measured in different organs (mantle, digestive gland and gonad) of both males and females of Donax trunculus L. (Mollusca, Bivalvia) exposed to cadmium (Cd). The samples were collected at El Battah beach, far from any source of pollution, and reared in the laboratory for four days. Cd was added to the rearing water at two previously determined sublethal concentrations (LC10 and LC25). Measurements of MTs were made at (0, 48 and 96 h). Cd exposure caused a significant induction (P < 0.05) of MTs in all studied organs in both sexes with a marked effect in females. The digestive gland had the highest MT levels, followed by the gonad and then mantle. Female and male individuals of this species differ in their susceptibility to Cd. This study supports the importance of sex and tissue in ecotoxicological studies. [ABSTRACT FROM AUTHOR]

The work aimed to identify promising areas for the search for primary hydrogen in Ukraine using a 3D P-velocity model of the mantle under Ukraine and its surroundings. The work uses a 3D P-velocity model of the mantle under the territory of Ukraine and its surroundings from a depth of 50 to 1700 km north of 50° NL and up to 2500 km to the south. The model is derived using ISC bulletin data from 1964 and is presented as horizontal and vertical cross-sections. Since the manifestation of hydrogen is primarily associated with the release of ultra-deep fluid tracks in the mantle, a brief analysis of them was presented. A detailed analysis of all nine superdeep mantle fluids isolated on the territory of Ukraine and their velocity characteristics was carried out. A comparison of the location of the routes of passage of superdeep fluids and the velocity structure of the mantle of the considered territory showed that they are confined to tectonically activated areas. In order to confirm the possible pre­sence of primary hydrogen in selected tracks of superdeep mantle fluids, heat flow density maps, a temperature map at a depth of 50 km, a map of the depth of the Moho boundary, a conductivity density map, and a fault map of the Ukrainian Shield were considered. A comparative analysis of maps of the location of superdeep mantle fluids and regions on the territory of Ukraine with increased heat flow, increased depth of the Moho boun­dary, and the presence of mantle conductors and faults was carried out. Summarizing the results of the comparative analysis, the most promising areas for the search for primary hydrogen were selected, corresponding to the following routes of superdeep fluids: f12, the northeastern part of f3, the southern part of f4 (the area of the Dnipro-Donetsk basin), the southwestern part of f1 (the area of the Western Ukrainian oil and gas-bearing region) and f9 and f10 (region of the South Crimean oil and gas-bearing province).

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 (δ37Cl) of variably metasomatized continental lithospheric mantle xenoliths from the Colorado Plateau and southern Rio Grande Rift (southwestern United States). Fertile mantle xenoliths that represent asthenosphere that has recently been emplaced at the base of the North American lithosphere have δ37Cl values of 0.0 ‰ to +0.1 ‰, suggesting that the convecting mantle has an average δ37Cl value similar to seawater and chondrites. In contrast, metasomatized xenoliths span a range of δ37Cl values from +0.1 ‰ to +1.9 ‰, extending above the average convecting mantle value. The range in δ37Cl values can be explained by mixing between a subduction-related fluid with δ37Cl values between +1.0 ‰ and +1.9 ‰ and a shallow crustal fluid with a δ37Cl value less than +0.3 ‰. The most likely source of the high δ37Cl subduction-related signature is the lower crust in the subducted Farallon plate. Lower crustal Cl likely entered the SCLM either through direct dehydration of lawsonite ± phengite in the deeply subducted Farallon plate or from a mixed serpentinite-oceanic crust source in the subducted Farallon. Regardless of the mechanism, this study provides evidence for subduction of crustal Cl into the mantle, which can introduce isotopic heterogeneity into the SCLM and has implications for the volatile cycling in the HIMU mantle and SCLM. [ABSTRACT FROM AUTHOR]