Fossil subduction zones are key to studying the deep geochemical cycles of C, O, and S. We analysed graphite-sulphide-bearing garnet clinopyroxenites from the External Ligurian (Northern Apennines, Italy), which serve as indicators of deep recycling of subducted crust. These rocks are among the only three known pyroxenite occurrences worldwide (along with Beni Bousera, Morocco, and Ronda, Spain) that formed through the crystallisation of eclogite-derived melts (P >= 3 GPa and 1100 degrees C), following a prolonged recycling history in off-craton mantle. In particular, a MOR-type heterogeneous gabbroic sequence was recycled into the mantle as eclogite 1.5-1.0 Ga ago, then partially melted and crystallised in the convective mantle, followed by subsolidus re-equilibration and exhumation. We analysed the redox state of garnets and clinopyroxenes associated with graphite and sulphides in garnet clinopyroxenites, that crystallised from a liquid produced by partial melting of recycled eclogite. Electron Energy Loss Spectroscopy within a transmission electron microscope and Synchrotron micro-M & ouml;ssbauer analyses revealed heterogeneities in Fe3+/Fe2+ distribution and its partitioning among mineral phases (Fe3+/Sigma Fe error is 0.03 for Electron Energy Loss Spectroscopy and 0.01-0.03 for Synchrotron micro-M & ouml;ssbauer). The analysed clinopyroxenites display three generations of clinopyroxenes: unexsolved crystals included in garnet cores with Fe3+/Sigma Fe = 0.16-0.38 (representative of eclogite-derived melt crystallisation in the asthenosphere), clinoenstatite exsolution-bearing grains with Fe3+/Sigma Fe = 0.03-0.10 (related to a first stage of exhumation in the lithospheric mantle), and Al-poorer rims without Fe3+ (related to the final stage of exhumation). In contrast, garnets have Fe3+/Sigma Fe-poor cores (<0.03) and slightly higher ratios in the rims (0.04-0.07). When considered together with the markedly higher Fe3+ contents in the earliest clinopyroxene generation, this pattern is consistent with a pressure-temperature-dependent partitioning of ferric iron from garnet to clinopyroxene during cooling from 1100 to 950 degrees C along the exhumation path. fO(2) calculations suggest a variation from more oxidised samples (Delta FMQ = -1.25 to 0) to more reduced ones (Delta FMQ = -4.2 to -1.6) at 3 GPa. At 1.5 GPa, Delta FMQ ranges from -1.2 to -0.6 down to < -5, indicating that graphite may have formed through reduction of a previously oxidised carbon phase. The oxidation state variations are linked to sub-solidus decompression, and not to S-C-related redox reactions, describing a closed system with no fluid/melt-rock interaction. Our results show that sulphur plays no role in controlling the redox state of these graphite-bearing mantle rocks, even over prolonged geological histories, and that variations in the redox state of carbon and iron in garnet and clinopyroxene can depend on pressure and temperature changes only, rather than from redox reactions, indicating that the intensive variable fO(2) can be decoupled from redox processes in a closed system.

Light-driven water splitting is a promising way to sustainably produce hydrogen as a renewable energy carrier. For this, immobilization of different catalytically active building blocks within soft and adaptive matrices plays a key role towards the defined preparation of multi-component hybrid materials. Herein, we present a combination of molybdenum phosphide (MoP, catalyst) and eosin Y (EY, photosensitizer), both immobilized within polyampholytic polydehydroalanine-graft-n-propyl phosphonic acid acrylamide (PDha-g-nPAA) graft copolymers. Analytical techniques such as nuclear magnetic resonance (NMR) and Raman spectroscopy confirmed successful graft copolymer formation, while X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) analyses further confirmed the immobilization of the EY and MoP, as evidenced by characteristic elemental signals and discrete MoP crystallites within the graft copolymer matrix. The catalytic activity for hydrogen evolution was investigated in aqueous triethanolamine (TEOA) solutions under green light irradiation (lambda >= 500 nm). This resulted in improved hydrogen production (similar to 2.5 mmolH2 h-1 g-1) when compared to a system without graft copolymer (similar to 0.9 mmolH2 h-1 g-1). The catalytic activity is attributed to the ability of the graft copolymer to stabilize and spatially confine the active units, while simultaneously acting as a bridge to facilitate proton and electron transfer between the EY and MoP.

The new mineral vegrandisite (BaCl2) was discovered at the porphyry gold deposit Biely Vrch, 3.5 km southeast of the town Detva, in the Central Slovak Volcanic Field. It occurs as a minor phase in salt melt inclusions hosted by vein quartz, where it forms small anhedral and transparent crystals up to 4 mu m long, accompanied by halite and several other daughter minerals, mainly javorieite, rinneite, chlorocalcite and hibbingite. Vegrandisite was identified by techniques embedded in transmission electron microscopy but many mineral properties, including optical and structural ones, are known from the synthetic BaCl2 analogue. Strongest bands in the Raman spectra include 114, 125, 187 cm(-1) and in the IR spectra in the region between 2852 and 2944 cm(-1). Vegrandisite in inclusions approaches the composition of BaCl2, but Sr (up to similar to 4.5 wt. %) and Br (up to similar to 2.1 wt. %) are also incorporated. It is orthorhombic, belongs to the space group Pnma. Obtained unit-cell parameters a = 7.80(3) angstrom; b = 4.71(2) angstrom; c = 9.60(9) angstrom, V = 352.68 (54) angstrom 3 are consistent with the published parameters of alpha-BaCl2 that exhibits a PbCl2-type (cotunnite) structure. Solid phases in salt melt inclusions, including vegrandisite, have crystallized from the salt melt on cooling of the inclusions. Late crystallization of BaCl2 is related to accumulation of the incompatible element barium in the residual salt melt. Parental salt melt evolved from a hypersaline liquid, accompanied by a magmatic vapor, that were exsolved from a shallow dioritic magma.

In cold, dense astrophysical environments dust grains are mixed with molecular ices. Chemistry in those dust/ice mixtures is determined by diffusion and reaction of molecules and radicals. However, investigations of diffusion of astrophysically relevant radicals and molecules across the surface and through the pores of cosmic dust grains and of surface reactions consequent to such diffusion are largely uncharted territory. This paper presents results of a study of a solid-state reaction of two molecular species, CO _2 and NH _3 , separated by a layer of porous silicate grain aggregates, analogues of cosmic dust. The experiments demonstrate that the presence of the dust layer was necessary for a pure thermal CO _2 + 2NH _3 reaction to proceed, leading to the formation of ammonium carbamate (NH _4 ^+ NH _2 COO ^− ), an ionic solid containing a complex organic moiety of prebiotic interest recently detected in a protoplanetary disk. This result speaks for (i) efficient diffusion of molecules on/within cosmic dust, (ii) an underestimated role for surface catalysis in the astrochemistry of cosmic dust, and (iii) potentially efficient dust-promoted chemistry in warm cosmic environments, such as protostellar envelopes and protoplanetary disks.

Abstract The Western Vardar ophiolite, a thrust sheet of oceanic crust and mantle obducted onto the Adriatic passive margin in the Late Jurassic, crops out along the entire Balkan Peninsula. The Mirdita Ophiolite forms the northern Albanian segment of this unit. In northeast Albania near Bajram Curri, a 200–700 m thick metamorphic sole is preserved at its base. The assembly of obducted mantle rocks and metamorphic sole constitutes a plate interface that formed during the intraoceanic subduction stage preceding obduction; we call this a fossil intraoceanic plate interface in this paper. This setting allows to study the interrelated tectonometamorphic evolution and rock-water interaction between the subducted and exhumed metamorphic sole and concomitant mantle wedge serpentinization in the overlying units. We combined detailed lithological and structural mapping with micro-scale analyses along this plate interface. Three tectonic units were distinguished. Mylonitic harzburgites overlie a tightly folded, tectonised subophiolitic mélange along a SE-dipping contact that defines the fossil intraoceanic plate interface. The tectonised subophiolitic mélange itself was separated into a structurally lower non-metamorphic broken formation and a higher metamorphic sole, separated by an isoclinally folded thrust. Within the metamorphic sole, the temperature and degree of deformation increase towards the structural top. Shear sense indicators in calcschists of the metamorphic sole show top to the west transport of the overriding units. All metamorphic sole lithologies were overprinted at lower greenschist-facies conditions, reflecting their exhumation from intraoceanic subduction. Corresponding microstructures indicate mineral growth at isotropic stresses, suggesting that deformation migrated into structurally lower, frontally accreted non-metamorphic units of the sub-ophiolitic mélange marking the start of obduction onto the passive Adriatic margin. Ongoing westward transport led to folding of the entire sub-ophiolitic succession. Harzburgites are more deformed towards the plate interface, forming a mylonitic fabric. There, harzburgites contain accessory Cr-rich spinel and the foliation is dissected by multiple generations of veins containing serpentine and magnetite. Vein density is highest along the plate interface and decreases up-section, suggesting that serpentinisation was triggered by devolatilisation reactions in the sediments of the metamorphic sole that were subducting below the harzburgites, and the upwards migration of volatiles into the overlying mantle wedge.

Apatite is present as an accessory phase in many meteorites and is often formed as a secondary product of aqueous alteration. Its propensity to incorporate rare earth elements (REE) results in apatite usually being the main REE-bearing phase in hydrously altered meteorites. Asteroid Ryugu is thought to have experienced pervasive aqueous alteration and material collected from the surface of Ryugu is expected to provide insight into asteroidal aqueous alteration processes without influence by terrestrial weathering. Morphologies and mineral associations of apatite grains from five rock fragments collected from the asteroid Ryugu by the Hayabusa2 spacecraft were examined and their REE concentrations were measured by synchrotron X-ray fluorescence (SXRF) spectroscopy. The main minerals associated with apatite are dolomite, magnetite, and pyrrhotite. Grain boundary corrosion of the interfaces between apatite assemblages and the surrounding matrix suggest that paragenetic formation on the asteroid was followed by a later episode of hydrous alteration. Light REE (LREE) concentration levels recorded at 20-150 times those of bulk CI levels together with a steady increase from LREE toward enrichment of medium REE (MREE, up to Er) at 50-400 times bulk CI levels may suggest postgenetic removal of LREE from Ryugu apatite grains by late-stage circulation of a hydrothermal fluid.

Shock‐related calcite twins are characterized in calcite‐bearing metagranite cataclasites within crystalline megablocks of the Ries impact structure, Germany, as well as in cores from the FBN1973 research drilling. The calcite likely originates from pre‐impact veins within the Variscan metagranites and gneisses, while the cataclasis is due to the Miocene impact. Quartz in the metagranite components does not contain planar deformation features, indicating low shock pressures (<7 GPa). Calcite, however, shows a high density (>1/μm) of twins with widths <100 nm. Different types of twins ( e ‐, f‐ , and r ‐twins) crosscutting each other can occur in one grain. Interaction of r ‐ and f ‐twins results in a ‐type domains characterized by a misorientation relative to the host with a misorientation angle of 35°–40° and a misorientation axis parallel to an a ‐axis. Such a ‐type domains have not been recorded from deformed rocks in nature before. The high twin density and activation of different twin systems in one grain require high differential stresses (on the order of 1 GPa). Twinning of calcite at high differential stresses is consistent with deformation during impact cratering at relatively low shock pressure conditions. The twinned calcite microstructure can serve as a valuable low shock barometer.

Knowledge of the shock behavior of planetary materials is essential to interpret shock metamorphism documented in rocks at hypervelocity impact structures on Earth, in meteorites, and in samples retrieved in space missions. Although our understanding of shock metamorphism has improved considerably within the last decades, the effects of friction and plastic deformation on shock metamorphism of complex, polycrystalline, non‐porous rocks are poorly constrained. Here, we report on shock‐recovery experiments in which natural granite was dynamically compressed to 0.5–18 GPa by singular, hemispherically decaying shock fronts. We then combine petrographic observations of shocked samples that retained their pre‐impact stratigraphy with distributions of peak pressures, temperatures, and volumetric strain rates obtained from numerical modeling to systematically investigate progressive shock metamorphism of granite. We find that the progressive shock metamorphism of granite observed here is mainly consistent with current classification schemes. However, we also find that intense shear deformation during shock compression and release causes the formation of highly localized melt veins at peak pressures as low as 6 GPa, which is an order of magnitude lower than currently thought. We also find that melt veins formed in quartz grains compressed to >10–12 GPa contain the high‐pressure silica polymorph stishovite. Our results illustrate the significance of shear and plastic deformation during hypervelocity impact and bear on our understanding of how melt veins containing high‐pressure polymorphs form in moderately shocked terrestrial impactites or meteorites.

AbstractMonazite-(Gd), ideally GdPO4, is a new mineral of the monazite group. It was discovered near Prakovce-Zimná Voda, ~23 km WNW of Košice, Western Carpathians, Slovakia. It forms anhedral domains (≤100 μm, mostly 10–50 μm in size), in close association with monazite-(Sm), Gd-bearing xenotime-(Y), Gd-bearing hingganite-(Y), fluorapatite and uraninite. All these minerals are hosted in a REE–U–Au quartz–muscovite vein, hosted in phyllites in an exocontact to granites. The density calculated using the average empirical formula and unit-cell parameters is 5.55 g/cm3. The average chemical composition measured by means of electron microprobe is as follows (wt.%): P2O5 29.68, As2O5 0.15, SiO2 0.07, ThO2 0.01, UO2 0.04, Y2O3 1.30, La2O3 3.19, Ce2O3 6.93, Pr2O3 1.12, Nd2O3 10.56, Sm2O3 17.36, Eu2O3 1.49, Gd2O3 22.84, Tb2O3 1.57, Dy2O3 2.27, CaO 0.21, total 99.67. The corresponding empirical formula calculated on the basis of 4 oxygen atoms is: (Gd0.30Sm0.24Nd0.15Ce0.10La0.05Dy0.03Y0.03Tb0.02Eu0.02Pr0.02Ca0.01)0.98P1.01O4. The ideal formula is GdPO4. The monazite-type structure has been confirmed by micro-Raman spectroscopy and selected-area electron diffraction. Monazite-(Gd) is monoclinic, space group P21/n, a = 6.703(1) Å, b = 6.914(1) Å, c = 6.383(1) Å, β = 103.8(1)°, V = 287.3(1) Å3 and Z = 4. The middle REE enrichment of monazite-(Gd) is shared with the associated Gd-bearing xenotime-(Y) to ‘xenotime-(Gd)’ and Gd-bearing hingganite-(Y). This exotic REE signature and precipitation of Gd-bearing mineral assemblage is a product of selective complexing and enrichment in middle REE in low-temperature hydrothermal fluids by alteration of primary uraninite, brannerite and fluorapatite on a micro-scale. The new mineral is named as an analogue of monazite-(La), monazite-(Ce), monazite-(Nd) and monazite-(Sm) but with Gd dominant among the REE.

The conversion of solar energy into electric power has been extensively studied, for example, by photovoltaics. However, photo-thermoelectric (P-TE) conversion as an effective solar-to-electricity conversion process is less studied. Here, we present an efficient full-solar-spectrum plasmonic absorber for scalable P-TE conversion based on a simple integration of light absorber and commercial thermoelectric modules. Our developed light absorber of silica-silver hybrid structures achieves an average absorption of 99.4% in the wavelength range from 200 to 2500 nm, which covers over 98% solar energy in this range. It thus appears fully matte black and is named black silver. The light absorber includes a hierarchical structure with Ag nanoparticles attached on three-dimensional SiO2 nanostructures, resulting in ultrahigh absorption. Strong localized surface plasmon resonance hybridization together with multiple scattering causes the perfect light absorption. Using the black silver as a light absorber for P-TE power generation, it can achieve a peak voltage density as high as 82.5 V m-2 under a solar intensity of 100 mW cm-2, which is large enough to power numerous electronic devices. By assembling 20 thermoelectric modules in series, we test their possibility of practical application, and they can also achieve an average voltage density of 70.66 V m-2. Our work opens up a promising technology that facilitates high-efficiency and scalable solar energy conversion via the P-TE effect.

Abstract. The sulfidic waste dumps of the historical mining sites Giftkies and Kaňk (Czech Republic) have been exposed to a temperate climate over decades. This exposure generated low-pH conditions caused by metal sulfide decomposition. Tin sulfides of the stannite–kësterite series [Cu2(Fe,Zn)SnS4] are common Sn minerals in the ores at the investigated sites. They decompose under acidic and oxidizing conditions and form in situ secondary precipitates. Compositional analyses of primary and secondary minerals were collected by electron microprobe to track the environmental mobility of the released elements during weathering. Transmission electron microscopy revealed a diffusion-driven alteration of stannite to Sn-rich chalcopyrite and the precipitation of native copper and silver from stannite. In assemblages containing arsenopyrite, an in situ and amorphous Sn–Fe–As (SFA)-rich phase precipitated close to the Sn sulfide. The SFA precipitate contains very little sulfur, which was probably released to the aqueous phase as oxidized species, whereas small amounts of Cu and Zn were captured by the SFA. This precipitate is metastable and acts as a temporaneous sink for mobile elements (Cu, Zn) and elements derived from acid-soluble silicates and phosphates (Ca, Si, Al, and P). With advanced weathering, complex redox reactions result in the precipitation of magnetite as an oxidation product of the sulfidic material under oxidative conditions. The stable minerals goethite and cassiterite mark the end of the weathering sequence and crystallized from the amorphous SFA precipitate.

Abstract Ferrous hydroxychlorides are geochemically important but less recognized mineral species due to their extreme sensitivity to oxidation and hydration in contact with air {typically they convert to akaganéite [Fe3+(O,OH,Cl)]}. Only the γ-form was previously known as the orthorhombic mineral hibbingite, associated with altered mafic intrusive rocks. In this study, we describe the β-polymorph of Fe2(OH)3Cl as a new mineral parahibbingite that was found in pyroxenite from the Karee platinum mine in the Bushveld Complex, South Africa. The two minerals were distinguished by a combination of Raman spectroscopy and FIB-SEM-TEM analytical techniques (TEM-EDX and TEM-SAED). They can be easily recognized by their distinct Raman spectra. Parahibbingite has two very strong vibration bands at ~3550 and 3560 cm–1, accompanied by much weaker bands at ~124 and 160 cm−1, while the Raman spectrum of hibbingite has a sharp, strong band at 3450 cm−1 and two moderate bands at 199 and 385 cm−1. Parahibbingite was found as fine-grained reaction rims at the contact of orthopyroxene phenocrysts and talc inside a drill core. It has a trigonal space group [R3m, a = 6.94(5) Å; c = 14.5(2) Å], with an empirical formula (Fe21.98+ Mn20.01+ Ca0.01)(OH)3.08Cl0.92. The origin of this mineral in the Bushveld Complex is most likely related to a late hydrothermal alteration of pyroxenite. Hibbingite forms as an abundant daughter mineral hosted by fluid inclusions and salt melt inclusions in hydrothermal quartz associated with granitic systems during cooling under reducing conditions. Such inclusions are common in Au-porphyry mineralization worldwide, such as the Biely Vrch (Slovakia) deposit studied in detail in this work. The lattice parameters obtained by TEM-SAED are a = 6.30 Å, b = 7.12 Å, and c = 9.89 Å. Hibbingite was recognized as the only phase that carries “water” (as a hydroxyl group) in otherwise water-free, salt melt inclusions. Furthermore, both hibbingite and parahibbingite should be considered as reservoirs for Cl and H2O in large volumes of altered basic and ultrabasic rocks. They can transport volatiles to shallow levels of subduction zones. Alternatively, their dissolution can fuel remobilization, transport, and deposition of sulfidic ores in saline fluids. Their detection, however, is difficult because of their sensitivity to oxidizing atmospheres. For example, in natural outcrops exposed to air, they may vanish, thus distorting estimates of their abundance and role in many processes that involve mineral-derived volatiles.

Pyroxenites are common compositional heterogeneities in the upper mantle and represent key lithologies in mantle deformation processes, as the local presence of pyroxene-rich compositions can weaken the mantle strength. Pyroxenites occur ubiquitously as variably deformed layers in most of oceanic and orogenic peridotite massifs, and thus can be used as a proxy to investigate the rheological behavior of the mantle in different geodynamic settings, including subduction zones. In the Ulten Zone (Tonale nappe, Eastern Alps, N Italy), numerous peridotite bodies occur within high-grade crustal rocks. Peridotites show a transition from coarse protogranular spinel lherzolites to finer-grained amphibole + garnet peridotites (Obata and Morten, 1987). Pyroxenites veins and dikes, transposed along the peridotite foliation, show a similar evolution from coarse garnet-free websterites to finer-grained garnet clinopyroxenites (Morten and Obata, 1983). This evolution has been interpreted to reflect cooling and pressure increase of pyroxenites and host peridotites from spinel- (1200 °C, 1.3-1.6 GPa) to garnet-facies conditions (850 °C and 2.7 GPa) within the mantle corner flow (Nimis and Morten, 2000). This results in the consequent formation of garnet at the expense of spinel. In particular, garnet initially formed as coronas around spinel and as exsolution lamellae in high-T pyroxenes, and later as neoblasts along the foliation of pyroxenites and host peridotites. Microstructures and crystallographic orientation data indicate that the transition from spinel- to garnet-facies conditions occurred in a deformation regime. Pyroxene porphyroclasts in garnet clinopyroxenites show well-developed crystallographic preferred orientation, high frequency of low-angle misorientations, and non-random distribution of the low-angle misorientation axes. These features indicate that pyroxene porphyroclasts primarily deformed by grain size insensitive (GSI) creep. Core-and-mantle microstructures in pyroxene porphyroclasts also suggest that GSI creep was aided by subgrain rotation (SGR) during recrystallization, leading the formation of smaller, neoblastic, and strain-free pyroxene grains around porphyroclasts. These recrystallized grains have been interpreted to deform by grain boundary sliding, i.e. a grain size sensitive (GSS) creep mechanism, as indicated by the occurrence of quadruple junctions between straight grain boundaries. Our rheological models also suggest that GSS creep of neoblastic pyroxenes occurred at differential stress of 40 MPa and strain rates of 10-18-10-15 s-1. The transition from GSI creep in the porphyroclasts to GSS creep in the neoblasts was accompanied not only by a reduction of the grain size of pyroxenes, but also by the crystallization of garnet along the pyroxenite foliation which facilitated pinning by second phase in the recrystallized matrix. This stabilized the fine-grained microtexture produced by the GSS creep process, and finally contributed to the rheological weakening of pyroxenites. Pyroxenites of Ulten Zone thus offer a unique opportunity to investigate the effects of mantle weakening on the processes that control the material exchange between crust and mantle at subduction zones. Morten, L., & Obata, M. (1983). Bulletin de Minéralogie, 106(6), 775-780. Nimis, P. & Morten, L. (2000). Journal of Geodynamics, 30(1-2), 93-115 Obata, M., & Morten, L. (1987). Journal of Petrology, 28(3), 599-623.

Peridotites of Ulten Zone (Eastern Alps, N Italy) show a transition from coarse protogranular spinel lherzolites to fine-grained amphibole + garnet peridotites, recorded by the crystallization of garnet coronas around spinel. Pyroxenite veins, transposed along the peridotite foliation, show a similar metamorphic evolution from coarse-grained (garnet-free) websterites to fine-grained garnet websterites. In both peridotites and websterites, garnet previously exsolved from porphyroclastic high-temperature pyroxenes and later crystallized along the foliation. This evolution has been interpreted to reflect cooling and pressure increase of websterites and host peridotites from spinel- to garnet-facies conditions. Microstructures and crystallographic orientation data indicate that the re-equilibration of garnet websterites in the garnet stability field occurred during deformation. Porphyroclastic pyroxenes have been interpreted to deform by dislocation glide and creep. In particular, TEM observations indicate the activation of the (100)[010] slip system in orthopyroxene. Core-and-mantle microstructures also suggest that dislocation creep was aided by subgrain rotation recrystallization, leading to the formation of neoblastic pyroxenes. These recrystallized grains deformed by diffusion-accommodated grain boundary sliding, as indicated by the occurrence of quadruple junctions and straight, aligned grain boundaries. The transition from dislocation creep to diffusion creep in websterites was accompanied by the crystallization of garnet along foliation, which triggered the pinning of the recrystallized matrix and stabilized the fine-grained microtexture for diffusion creep, promoting rheological weakening. Garnet websterites of Ulten Zone thus offer a unique opportunity to investigate the effects of reaction softening during the corner flow in the supra-subduction lithospheric mantle induced by the descending slab. Plain Language Summary When tectonic plates converge, one plate slides beneath the other plate descending into the Earth's mantle. During this process (the so-called subduction), rocks forming the Earth's mantle, such as peridotites and pyroxenites, can be dragged to great depths and later transported back to the surface by a combination of two processes known as corner flow and exhumation. Rocks that experienced this journey are now exposed at the surface only in few mountain belts in the world (such as the European Alps) and represent natural laboratories to study the processes that occur at great depths in the Earth's mantle. In this study, we reconstruct the metamorphic and deformation evolution of pyroxenites of the Ulten Zone (Eastern Alps, N Italy). Minerals in pyroxenites deformed through different deformation processes, including dislocation creep and diffusion creep mechanisms. Our data indicate that minerals within pyroxenites record a transition in the deformation mechanism from dislocation to diffusion creep. This switch of the deformation mechanism was responsible for a significant rheological weakening of pyroxenites, suggesting that pyroxenites can play a major role in the processes that control the deformational behavior of the Earth's mantle.

Organic microfossils in Meso- and Neoproterozoic rocks are of key importance to track the emergence and evolution of eukaryotic life. An increasing number of studies combine Raman spectroscopy with synchrotron-based methods to characterize these microfossils. A recurring observation is that Raman spectra of organic microfossils show negligible variation on a sample scale and that variation between different samples can be explained by differences in thermal maturation or in the biologic origin of organic precursor material. There is a paucity of work, however, that explores the extent to which the petrographic framework and diagenetic processes might influence the chemical structure of organic materials. We present a detailed Raman spectroscopy-based study of a complex organic microfossil assemblage in the ca. 1 Ga old Angmaat Formation, Baffin Island, Canada. This formation contains abundant early diagenetic chert that preserves silicified microbial mats with numerous, readily identifiable organic microfossils. Individual chert beds show petrographic differences with discrete episodes of cementation and recrystallization. Raman spectroscopy reveals measurable variation of organic maturity between samples and between neighboring organic microfossils of the same taxonomy and taphonomic state. Scanning transmission X-ray microscopy performed on taphonomically similar coccoidal microfossils from the same thin section shows distinct chemical compositions, with varying ratios of aromatic compounds to ketones and phenols. Such observations imply that geochemical variation of organic matter is not necessarily coupled to thermal alteration or organic precursor material. Variation of the Raman signal across single samples is most likely linked to the diagenetic state of analyzed materials and implies an association between organic preservation and access to diagenetic fluids. Variation in the maturity of individual microfossils may be a natural outcome of local diagenetic processes and potentially exceeds differences derived from precursor organic material. These observations stress the importance of detailed in situ characterization by Raman spectroscopy to identify target specimens for further chemical analysis.

Black body materials are promising candidates to meet future energy demands, as they are able to harvest energy from the total bandwidth of solar radiation. Here, we report on high-absorption near-blackbody-like structures (>98% for a wide solar spectrum range from 220 to 2500 nm) consisting of a silica scaffold and Ag nanoparticles with a layer thickness below 10 μm, fabricated using metastable atomic layer deposition (MS-ALD). Several effects contribute collectively and in a synergistic manner to the ultrahigh absorption, including the pronounced heterogeneity of the nanoparticles in size and shape, particle plasmon hybridization, and the trapping of omnidirectionally scattered light in the 3D hierarchical hybrid structures. We propose that, in the future, MS-ALD needs to be considered as a simple and promising method to fabricate blackbody materials with excellent broadband absorption.

This work reports the facile synthesis of a Sn–P composite combined with nitrogen doped hard carbon (NHC) obtained by ball‐milling and its use as electrode material for sodium ion batteries (SIBs). The “Sn 4 P 3 ”/NHC electrode (with nominal composition “Sn 4 P 3 ”:NHC = 75:25 wt%) when coupled with a diglyme‐based electrolyte rather than the most commonly employed carbonate‐based systems, exhibits a reversible capacity of 550 mAh g electrode −1 at 50 mA g −1 and 440 mAh g electrode −1 over 500 cycles (83% capacity retention). Morphology and solid electrolyte interphase formation of cycled “Sn 4 P 3 ”/NHC electrodes is studied via electron microscopy and X‐ray photoelectron spectroscopy. The expansion of the electrode upon sodiation (300 mAh g electrode −1 ) is only about 12–14% as determined by in situ electrochemical dilatometry, giving a reasonable explanation for the excellent cycle life despite the conversion‐type storage mechanism. In situ X‐ray diffraction shows that the discharge product is Na 15 Sn 4 . The formation of mostly amorphous Na 3 P is derived from the overall (electro)chemical reactions. Upon charge the formation of Sn is observed while amorphous P is derived, which are reversibly alloying with Na in the subsequent cycles. However, the formation of Sn 4 P 3 can be certainly excluded.

The electrode behavior of exfoliated MoS2 is studied in an all-solid-state lithium-ion battery. MoS2 nanosheets with a crystallite thickness of about 6 nm are synthesized by chemical exfoliation of...