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The Steingarden Nunataks (STG) 07009 iron meteorite was found in 2007 during a search campaign in Queen Maud Land, Antarctica, carried out by the Bundesanstalt für Geowissenschaften und Rohstoffe (BGR, Hannover, Germany). It was collected as one complete individual specimen with regmaglypts and weighing ~ 32.6 kg. The main mass (32.2 kg) is stored at the BGR, whereas the type specimen (36.6 g) is kept at the Natural History Museum, Vienna. Macroscopically, the meteorite appears well preserved and does not show any oxidation features in its interior. Textural studies of etched platelets revealed that the meteorite is a plessitic octahedrite with almost all kamacite spindles (apparent width = 0.08 ± 0.03 mm, N = 30) having nuclei of schreibersite. Compositionally, kamacite and schreibersite are mainly uniform. However, a detailed electron microprobe investigation revealed that, in places, the spindles contain schreibersite-metal intergrowths, exhibiting complex textures and compositions. Based on bulk chemistry data, STG 07009 was classified as ungrouped iron with no close relatives. Age calculations based on accelerator mass spectroscopy of the cosmogenic radionuclides ¹⁰Be, ²⁶Al, and ³⁶Cl gave for STG 07009 a cosmic-ray exposure age of 780 ± 100 Myr and a relatively young terrestrial age of 75 ± 33 kyr. Der Eisenmeteorit Steingarden Nunataks (STG) 07009 wurde 2007 im Rahmen einer von der Bundesanstalt für Geowissenschaften und Rohstoffe (BGR, Hannover, Deutschland) im Queen Maud Land, Antarktis durchgeführten Suchkampagne gefunden. STG 07009 wurde als 32,6 kg schweres komplettes Individuum mit Regmaglypten aufgesammelt. Die Hauptmasse (32,2 kg) wird an der BGR verwahrt, das Typmaterial (36,6 g) ist im Naturhistorischen Museum Wien deponiert. Makroskopisch erscheint der Meteorit in gut erhaltenem Zustand und weist keinerlei Rostanzeichen in seinem Inneren auf. Gefügestudien an geätzten Plättchen ergaben, dass es sich beim Meteoriten um einen plessitischen Oktaedriten handelt, wobei fast alle Kamazit-Spindeln (gemessene Breite = 0,08 ± 0,03 mm, N = 30) einen aus Schreibersit bestehenden Kern aufweisen. In den meisten Spindeln weisen Kamazit und Schreibersit jeweils denselben einheitlichen Chemismus auf. Detailuntersuchungen mittels Elektronenstrahlmikrosonde zeigten, dass die Spindeln bereichsweise Verwachsungen von Schreibersit und Metall enthalten, die komplexe Gefüge und Chemismen aufweisen. Aufgrund des ermittelten Pauschalchemismus wurde STG 07009 als ungruppierter Eisenmeteorit klassifiziert. Dabei konnte keine chemische Verwandtschaft mit anderen ungruppierten Eisen festgestellt werden. Basierend auf der mittels Beschleuniger-Massenspektrometrie gemessenen kosmogenen Radionuklide ¹⁰Be, ²⁶Al, und ³⁶Cl wurde für STG 07009 ein kosmisches Bestrahlungsalter von 780 ± 100 Ma und ein relativ junges terrestrisches Alter von 75 ± 33 ka errechnet.

When studying carbon (C) sequestration in soil, it is necessary to recognize the maximal storage potential and the main influencing factors, including the climate, land use, and soil properties. Here, we hypothesized that the silt and clay contents in soils as well as the clay mineralogy are the main factors affecting the maximal C and N storage levels of soils. This hypothesis was evaluated using a database containing the organic C contents of topsoils separated by ultrasonic dispersion to determine the particle size fractions. The slopes of the linear regressions between the C contents in silt and clay to the soil organic C (SOC) and between the N contents in silt and clay to the total N content were independent of the clay mineralogy (2:1, 1:1, calcareous soil, amorphous clays), climate type (tropical, temperate, and Mediterranean), and land use type (cropland, grassland, and forest). This clearly shows that the silt and clay content is the main factor defining an upper SOC level, which allowed us to propose a generalized linear regression (R 2  > 0.95) model with a common slope, independent of the land use and climate type, to estimate the soil C sequestration potential. The implications of these findings are as follows: (1) a common slope regression was accurately calculated (0.83 ± 0.02 for C-silt + clay < 63 μm and 0.81 ± 0.02 for C-silt + clay < 20 μm) and (2) there was no asymptotic pattern found to support the existence of an SOC saturation pool.

Permanent wilting point (PWP) is generally used to ascertain plant resistance against abiotic drought stress and designated as the soil water content (θ) corresponding to soil suction (ψ) at 1500 kPa obtained from the soil water retention curve. Determination of PWP based on only pre-assumed ψ may not represent true wilting condition for soils with contrasting water retention abilities. In addition to ψ, there is a need to explore significance of additional plant parameters (i.e., stomatal conductance and photosynthetic status) in determining PWP. This study introduces a new framework for determining PWP by integrating plant leaf response and ψ during drought. Axonopus compressus were grown in two distinct textured soils (clayey loam and silty sand), after which drought was initiated till wilting. Thereafter, ψ and θ within the root zone were measured along with corresponding leaf stomatal conductance and photosynthetic status. It was found that coarse textured silty sand causes wilting at much lower ψ (≈ 300 kPa) than clayey loam (≈ 1600 kPa). Plant response to drought was dependent on the relative porosity and mineralogy of the soil, which governs the ease at which roots can grow, assimilate soil O 2 , and uptake water. For clay loam, the held water within the soil matrix does not facilitate easy root water uptake by relatively coarse root morphology. Contrastingly, fine root hair formation in silty sand facilitated higher plant water uptake and doubled the plant survival time.

Porosity and permeability are the key factors in assessing the hydrocarbon productivity of unconventional (shale) reservoirs, which are complex in nature due to their heterogeneous mineralogy and poorly connected nano- and micro-pore systems. Experimental efforts to measure these petrophysical properties posse many limitations, because they often take weeks to complete and are difficult to reproduce. Alternatively, numerical simulations can be conducted in digital rock 3D models reconstructed from image datasets acquired via e.g., nanoscale-resolution focused ion beam–scanning electron microscopy (FIB-SEM) nano-tomography. In this study, impact of reservoir confinement (stress) on porosity and permeability of shales was investigated using two digital rock 3D models, which represented nanoporous organic/mineral microstructure of the Marcellus Shale. Five stress scenarios were simulated for different depths (2,000–6,000 feet) within the production interval of a typical oil/gas reservoir within the Marcellus Shale play. Porosity and permeability of the pre- and post-compression digital rock 3D models were calculated and compared. A minimal effect of stress on porosity and permeability was observed in both 3D models. These results have direct implications in determining the oil-/gas-in-place and assessing the production potential of a shale reservoir under various stress conditions.

Crack evolution in a rock depends on the mineralogy, microstructure and fabric of specific rock type. This study aims to investigate how mineralogy and grain shape affect the microcrack initiation and propagation of granite rock, which contains plagioclase, quartz, k-feldspar, biotite and amphibole, during uniaxial compression loading. Physico-mechanical properties and microcrack features such as linear microcrack density (LMD) and microcrack type were investigated. By acoustic emission (AE) measurements, damage stress thresholds were identified. Then, crack characteristics of a fresh sample were compared with the samples that were loaded until damage threshold stresses. The results demonstrate that at an early stage of loading, pre-existing microcracks growth and LMD of intergranular crack increase. In the elastic phase, all microcracks types increase at the same rate. When the loading reaches to the strength limit of the sample, the total LMD reduced, because cracks start to coalesce and form new and large transgranular microcrack. Investigating crack propagation in mineral shows that at first, microcrack generates in biotite and at last in quartz. Plagioclase has the highest LMD and microcracks usually formed within the cleavage plane, but alteration and inclusions of tiny minerals can drastically change the LMD and orientation of microcracks. Biotite can terminate or let the microcrack to pass through the crystal based on the orientation of the microcrack plane and cleavage microcrack within the mineral. Furthermore, crystals with an aspect ratio higher than two have higher LMD. By getting close to the uniaxial compression strength, more microcracks appear close to the grain boundary which increases the circularity of the grain.

Crops may take benefits from silicon (Si) uptake in soil. Plant available Si (PAS) can be affected by natural weathering processes or by anthropogenic forces such as agriculture. The soil parameters that control the pool of PAS are still poorly documented, particularly in temperate climates. In this study, we documented PAS in France, based on statistical analysis of Si extracted by CaCl2 (SiCaCl2) and topsoil characteristics from an extensive dataset. We showed that cultivation increased SiCaCl2 for soils developed on sediments, that cover 73% of France. This increase is due to liming for non-carbonated soils on sediments that are slightly acidic to acidic when non-cultivated. The analysis performed on non-cultivated soils confirmed that SiCaCl2 increased with the < 2 µm fraction and pH but only for soils with a < 2 µm fraction ranging from 50 to 325 g kg−1. This increase may be explained by the < 2 µm fraction mineralogy, i.e. nature of the clay minerals and iron oxide content. Finally, we suggest that 4% of French soils used for wheat cultivation could be deficient in SiCaCl2.

Classified as Regosols in the Food and Agriculture Organization (FAO) Taxonomy, purple soils formed from purple rocks and are mainly distributed in the Sichuan Basin of southwestern China. A number of studies have focused on the soil water, nutrients, texture and erosion of purple soils. This study was conducted to understand the lithological features of the related purple rocks and their effects on the pedogenesis of purple soils in the Sichuan Basin. The results showed the following: due to variability in the paleoenvironment, purple rocks mainly consist of sandstone and mudstone with various stratal thicknesses and various particle sizes. The lithology of the purple rocks leads the purple soils have an obvious inheritance from their parent rocks. An apparent purple color and numerous rock fragments derived from the purple parent rock are observed throughout the profile, with no clear soil stratification. The particle size contents of the purple soils are closely related to those of their parent rocks. The clay-sized fractions in the purple soils are generally dominated by illite, vermiculite, chlorite, and montmorillonite with little quartz and with or without kaolinite, which is generally the same as that in the parent purple rocks. In addition, the purple soils are characterized by obvious inherited mineralogy, chemical composition, pH value, OM content and nutrient content. Therefore, the diagenetic environment determined the lithology of the purple rock, and the lithology of the purple rock determined the pedogenic characteristics of the purple soil to some extent. Purple soils are characterized by rapid physical weathering and pedogenetic processes and slow chemical pedogenetic processes.

Hydrogen is potentially a key light element in the Earth's core. Determining the stability of iron hydride is essential for Earth's core mineralogy applications. We investigated the thermal stabilities of a range of Fe‐H binaries at core P‐T conditions. It is concluded that face‐centered cubic phase FeH is stable in the Earth's inner core. The high mobility of hydrogen in the Fe lattice suggests that hydrogen is transferred to a superionic state under the inner core conditions, where the superionic state transfer temperature of H in Fe fcc lattice is ∼500 K higher than that in hcp Fe system. The H concentration in the inner core is estimated to be ∼0.92 wt% to explain its density deficit, this value was further constrained to ∼0.21 wt% by matching the density jump at the inner‐core boundary. H alongside other light elements are required to account for the geophysical observations of the Earth's inner core. Key Points Fcc phase FeH was found to be stable under inner core conditions H is superionic in both fcc and hcp lattices at inner core temperature but the transition temperature is 500 K higher in the fcc system The H concentration in the inner core has been constrained to be ∼0.21 wt% by matching the density jump at the inner‐core boundary

Diamond exploration over the past decade has led to the discovery of a new province of kimberlitic pipes (the Webb Province) in the Gibson Desert of central Australia. The Webb pipes comprise sparse macrocrystic olivine set in a groundmass of olivine, phlogopite, perovskite, spinel, clinopyroxene, titanian‐andradite and carbonate. The pipes resemble ultramafic lamprophyres (notably aillikites) in their mineralogy, major and minor oxide chemistry, and initial 87Sr/86Sr and εNd‐εHf isotopic compositions. Ion probe U‐Pb geochronology on perovskite (806 ± 22 Ma) indicates the eruption of the pipes was co‐eval with plume‐related magmatism within central Australia (Willouran‐Gairdner Volcanic Event) associated with the opening of the Centralian Superbasin and Rodinia supercontinent break‐up. The equilibration pressure and temperature of mantle‐derived garnet and chromian (Cr) diopside xenocrysts range between 17 and 40 kbar and 750–1320°C and define a paleo‐lithospheric thickness of 140 ± 10 km. Chemical variations of xenocrysts define litho‐chemical horizons within the shallow, middle, and deep sub‐continental lithospheric mantle (SCLM). The shallow SCLM (50–70 km), which includes garnet‐spinel and spinel lherzolite, contains Cr diopside with weakly refertilized rare earth element compositions and unenriched compositions. The mid‐lithosphere (70–85 km) has lower modal abundances of Cr diopside. This layer corresponds to a seismic mid‐lithosphere discontinuity interpreted as pargasite‐bearing lherzolite. The deep SCLM (>90 km) comprises refertilized garnet lherzolite that was metasomatized by a silicate‐carbonatite melt. Key Points A new alkaline province in Central Australia is described. Intrusions resemble aillikites based on mineralogy and Sr‐Nd‐Hf isotopes Aillikites were emplaced at 806 Ma along the rifted margin of the Centralian Superbasin in response to Rodinia breakup A seismic and petrological mid‐lithosphere discontinuity at 80–85 km depth may relate to pargasite channels

With growing population and urbanization, there is an increasing exploitation of natural resources, and this often results to environmental pollution. In this review, the levels of heavy metal in lentic compartments (water, sediment, fishes, and aquatic plants) over the past two decades (1997–2017) have been summarized to evaluate the current pollution status of this ecosystem. In all the compartments, the heavy metals dominated are zinc followed by iron. The major reason could be area mineralogy and lithogenic sources. Enormous quantity of metals like iron in estuarine sediment is a very natural incident due to the permanently reducing condition of organic substances. Contamination of cadmium, lead, and chromium was closely associated with anthropogenic origin. In addition, surrounding land use and atmospheric deposition could have been responsible for substantial pollution. The accumulation of heavy metals in fishes and aquatic plants is the result of time-dependent deposition in lentic ecosystems. Moreover, various potential risk assessment methods for heavy metals were discussed. This review concludes that natural phenomena dominate the accumulation of essential heavy metals in lentic ecosystems compared to anthropogenic sources. Amongst other recent reviews on heavy metals from other parts of the world, the present review is executed in such a way that it explains the presence of heavy metals not only in water environment, but also in the whole of the lentic system comprising sediment, fishes, and aquatic plants.