Iron Enrichment Research Articles

Constraints on the composition and temperature of LLSVPs from seismic properties of lower mantle minerals

Seismic observations have suggested the presence of two Large Low Shear Velocity Provinces (LLSVPs) in the lowermost mantle whose nature and origin are still debated. Several studies have tried to infer their potential composition using seismic observations with the hope to identify their formation mechanism. In particular, compositions enriched in iron (∼12–14 wt%) and bridgmanite (∼90 vol%) have been identified as promising candidates. Interestingly, these characteristics are somewhat consistent with the cumulates produced by the solidification of a primitive magma ocean, except that the iron enrichment should be much larger (>20 wt%). Here, we provide a reappraisal of potential LLSVPs compositions based on an improved mineralogical model including, in particular, the effects of alumina. We systematically investigate the effects of six parameters: FeO and Al2O3 content, proportion of CaSiO3 and bridgmanite (so that the proportion of ferropericlase is implicitly investigated), Fe3+/∑Fe and temperature contrast between far-field mantle and LLSVPs. From the 81 millions cases studied, only 79000 cases explain the seismic observations. Nevertheless, these successful cases involve a large range of parameters with, for instance, FeO content between 12–25 wt% and Al2O3 content between 3–17 wt%. We then apply a principal component analysis (PCA) to these cases and find two robust results: (i) the proportion of ferropericlase should be low (<6 vol%); (ii) the formation of Fe3+-bearing bridgmanite is much more favored compared to other iron-bearing components. Following these results, we identify two end-member compositions: a Bm-rich and a CaPv-rich one. For each end-member composition, a large range of parameters is possible. We note, however, that a low temperature contrast (<500 K) is favored, and that a certain proportion between FeO content, Al2O3 and oxidation state should be maintained. Finally, we discuss different scenarios for the formation of LLSVPs and propose that investigating the mineral proportion produced by each scenario is the best way to evaluate their relevance. For instance, the solidification of a primitive magma ocean may produce FeO and Al2O3 contents similar to those suggested by our analysis. However, the mineral proportion of such reservoirs is not well-constrained and may contain a larger proportion of ferropericlase than what is allowed by our results.

The X-SHOOTER/ALMA Sample of Quasars in the Epoch of Reionization. I. NIR Spectral Modeling, Iron Enrichment, and Broad Emission Line Properties

Abstract We present X-SHOOTER near-IR spectroscopy of a large sample of 38 luminous (M 1450 = −29.0 to −24.4) quasars at 5.78 &lt; z &lt; 7.54, which have complementary [C ii] 158μm observations from ALMA. This X-SHOOTER/ALMA sample provides us with the most comprehensive view of reionization-era quasars to date, allowing us to connect the quasar properties with those of its host galaxy. In this work we introduce the sample, discuss data reduction and spectral fitting, and present an analysis of the broad emission line properties. The measured Fe ii/Mg ii flux ratio suggests that the broad-line regions of all quasars in the sample are already enriched in iron. We also find the Mg ii line to be on average blueshifted with respect to the [C ii] redshift with a median of −391 km s−1. A significant correlation between the Mg ii−[C ii] 158μm and C iv−[C ii] 158μm velocity shifts indicates a common physical origin. Furthermore, we fRequently detect large C iv–Mg ii emission line velocity blueshifts in our sample with a median value of −1848 km s−1. While we find all other broad emission line properties not to be evolving with redshift, the median C iv–Mg ii blueshift is much larger than found in low-redshift, luminosity-matched quasars (−800 km s−1). Dividing our sample into two redshift bins, we confirm an increase of the average C iv–Mg ii blueshift with increasing redshift. Future observations of the rest-frame optical spectrum with the James Webb Space Telescope will be instrumental in further constraining the possible evolution of quasar properties in the epoch of reionization.

Impaired Hepcidin Metabolism Promotes Hemolysis Induced Hepatobiliary Injury in Sickle Cell Disease

Sickle cell disease (SCD) is an autosomal-recessive-genetic disorder that affects millions of people worldwide. Although hepatic crisis affects 10-40% of hospitalized SCD patients and can progress to fatal liver failure, the current treatment is primarily supportive and the molecular pathophysiology remains largely unknown. We found that transgenic, humanized SCD mice developed liver injury with age, manifested by increased inflammation, necrosis and hepatic iron accumulation. The presence of iron particles in SCD liver was confirmed by transmission electron micrograph (TEM) analysis and prussian blue staining which revealed increased iron accumulation in the central and midzonal region of the SCD liver tissue. An increase in aggregates of iron pigment reminiscent of hemosiderin-laden macrophages was also observed in SCD liver tissue. Interestingly, the SCD mice also showed significant enrichment of both hepatic (p=0.02) and serum iron (p=0.04) compared to control AS mice. We determined the expression level of genes commonly involved in iron homeostasis by RT-PCR. Interestingly, a significantly lower expression level of hepcidin transcripts was observed in the hepatocytes of SCD mice compared to control mice (AS) (p=0.01). In order to define the pathways controllinghepcidintranscription in SCD, we performed an RNA-seq analysis in the liver of SCD mice. Remarkably, our data showed significant misexpression of BMP signaling pathways. Further analysis revealed a significant misexpression in BMP2 and 6 levels in the liver of SCD mice by western blot. Reduced levels of hepcidin were also confirmed in serum samples from SCD patients compared to controls. Work is currently underway to understand how BMP2/6 might hypothetically regulate hepcidin expression in the liver. In summary, our results reveal a significant defect in iron homeostasis in the liver of SCD mice, suggesting that impaired iron homeostasis may contribute to hepatobiliary injury in SCD independent of blood transfusions. Our study also highlights the importance of hepcidin as potential therapeutic target in regulation of hepatic injury in SCD. Disclosures No relevant conflicts of interest to declare.

Iron Mobility During Diagenesis at Vera Rubin Ridge, Gale Crater, Mars

AbstractTheCuriosityrover investigated a topographic structure known as Vera Rubin ridge, associated with a hematite signature in orbital spectra. There,Curiosityencountered mudstones interpreted as lacustrine deposits, conformably overlying the 300 m‐thick underlying sedimentary rocks of the Murray formation at the base of Mount Sharp. While the presence of hematite (α‐Fe2O3) was confirmed in situ by both Mastcam and ChemCam spectral observations and by the CheMin instrument, neither ChemCam nor APXS observed any significant increase in FeOT(total iron oxide) abundances compared to the rest of the Murray formation. Instead,Curiositydiscovered dark‐toned diagenetic features displaying anomalously high FeOTabundances, commonly observed in association with light‐toned Ca‐sulfate veins but also as crystal pseudomorphs in the host rock. These iron‐rich diagenetic features are predominantly observed in “gray” outcrops on the upper part of the ridge, which lack the telltale ferric signature of other Vera Rubin ridge outcrops. Their composition is consistent with anhydrous Fe‐oxide, as the enrichment in iron is not associated with enrichment in any other elements, nor with detections of volatiles. The lack of ferric absorption features in the ChemCam reflectance spectra and the hexagonal crystalline structure associated with dark‐toned crystals points toward coarse “gray” hematite. In addition, the host rock adjacent to these features appears bleached and shows low‐FeOTcontent as well as depletion in Mn, indicating mobilization of these redox‐sensitive elements during diagenesis. Thus, groundwater fluid circulations could account for the remobilization of iron and recrystallization as crystalline hematite during diagenesis on Vera Rubin ridge.

Three-dimensional structural modeling and deformation analysis of Archean magnetite quartzite from the Anshan–Benxi area, northeastern China

The factors controlling the migration and enrichment of iron in Archean banded iron formations are important for understanding the formation of iron ore resources. Here we present, for the first time, a micro-three-dimensional modeling method that can be applied to hand specimens of iron ores. This method and petrographic observations, electron probe microanalysis, and the structural deformation characteristics of magnetite quartzite are used to assess the mechanisms of iron enrichment in such ores. The Anshan–Benxi area is located in the eastern part of the North China Craton, and is one of the most significant Archean banded iron deposits in the world. Magnetite quartzite is developed on a large scale in this area, which has experienced complex structural deformation, and thus these samples are ideal for our study. As such, we undertook micro-scale, three-dimensional structural modeling of representative hand specimens of the magnetite quartzite. Our methodology involved combined surface and internal modeling. The rock samples were sliced at fixed intervals and detailed scanned images of the slices were obtained, which enabled a three-dimensional model to be constructed of each sample. These three-dimensional models allow the deformational characteristics of the banded iron formation to be quantified on a hand specimen scale. Petrographic analysis showed that the banded magnetite quartzite has experienced brittle deformation, and electron microprobe analysis revealed iron enrichment in the fold axes. Structural deformation, such as folding and ductile shearing, has a controlling effect on iron enrichment, and the microscopic three-dimensional modeling method provides a new approach for studying the deformational characteristics of iron-bearing formations.

Nano-decocted ferrous polysulfide coordinates ferroptosis-like death in bacteria for anti-infection therapy

Abstract Antibacterial nanomaterials provide promising alternative strategies to combat the global challenge of bacterial infection due to deteriorating resistance. However, few have been applied for intracellular bacteria killing or in vivo therapy due to potential cytotoxicity and poor biocompatibility. Here we present a strategy to generate formula suitable for in vivo anti-infective therapy by decocting antibacterial nanomaterial. An aqueous formula containing ferrous iron and polysulfide (Fe(II)Snaq) is prepared by a decoction procedure using nano-iron sulfide (nFeS) as raw substance. Theoretical calculation indicated that replacement of a sulfur atom by an oxygen atom occurred, resulting in polysulfide release and iron dissolution. The Fe(II)Snaq decocted from nFeS induced bacterial death with ferroptosis-like hallmarks, including iron enrichment, lipid peroxidation, and glutathione (GSH) depletion. The antibacterial action of Fe(II)Snaq was dependent on ferrous iron, which could be inhibited by iron chelators, ferroptosis inhibitors, and GSH, while the polysulfide prevented ferrous iron oxidation and counteracted GSH. Furthermore, Fe(II)Snaq not only killed up to 99 % of planktonic bacteria within 5 min, but also suppressed up to 90 % of intracellular Staphylococcus aureus without triggering cytotoxicity to host cell. Administration of Fe(II)Snaq achieved equivalent therapeutic effect to vancomycin for infectious pneumonia treatment and significantly prolonged the survival period of septic mice. These results indicate that aqueous ferrous polysulfide can induce ferroptosis- like death in bacteria and may be formulated as an antibacterial alternative for anti-infection therapy.

Shallow‐marine Cretaceous oceanic red beds from the southern Tethyan Himalaya, Tibet, western China: Biostratigraphy, microfacies analysis, and global correlations

The “Cretaceous oceanic red beds (CORBs)” associated with “oceanic oxic events” have become a hot topic for geologists from around the world. In southern Tibet, the CORBs are widely distributed in the Upper Cretaceous of the northern Tethys Himalayas, but they have never been reported from the southern Tethyan Himalaya (Tibet, China). A mixed Upper Cretaceous carbonate‐shale succession is well exposed in the Gyabukeqing section of Guru town, Yadong County, southern Tibet, which tectonically belongs to the southern Tethyan Himalaya. These sedimentary strata constitute the transition from the Gangbacunkou Formation shale towards the Zongshan Formation limestone through the Jiubao Formation alternations of marl and shale. The Gangbacunkou Formation is characterized by grey‐greenish shales occasionally interspersed with laminated marls, followed by the Jiubao Formation composed of marls with interbeds of shales, which is overlain by the limestones of the Zongshan Formation. A 5‐m‐thick purplish marl bed was found from the lower Jiubao Formation in the Gyabukeqing section, and these reddish marls are assignable to shallow marine red beds. Detailed foraminifer biostratigraphy established five planktic foraminifer zones: Dicarinella covcavata, D. asymetrica, Globotruncanita elevata, G. ventricosa, and Radotruncana calcarata throughout the entire Upper Cretaceous succession in the Gyabukeqing section. The reddish marl beds are constrained as middle Campanian in age as they are calibrated to the middle part of the foraminifer Radotruncana calcarata Zone. As a comparison, the typical CORBs of pelagic–hemipelagic settings are also documented from the Upper Cretaceous of the northern Tethys Himalayas in southern Tibet. A total of 10 microfacies were recognized from the entire sequence of the Upper Cretaceous outer shelf‐slope settings in the Yadong area, southern Tibet. The Yadong red marl beds represent the sedimentation of the foraminiferal biomicrite/foraminiferal wackestone and mudstone/mudrock microfacies, pointing to a shallow marine continental shelf margin setting. Global biostratigraphic correlations indicate that the Yadong red marl beds are coeval with the typical CORBs of the Gyangze and Kangmar documented from the northern Tethys Himalayas in this study or reported previously from the same region as well as elsewhere in the world. The Yadong red beds also are comparable in lithology and biostratigraphy with the shallow marine red beds documented from Europe, and they all may represent the contemporaneous deposition of the CORBs in shallow shelf. These shallow marine CORBs share similar depositional mechanisms: undergoing a phase of iron and manganese enrichment in seawater due to injection of deep sea anoxic water to shallow shelf, followed by oxidization in shallow settings or being oxidized during diagenetic process or a response to the oxygenation of coeval CORBs in deep seas.

Investigation of carbothermic microwave reduction followed by acid leaching for recovery of iron and aluminum values from Indian red mud

The red mud is an abundantly generated by-product of the aluminum industry rich in iron values mainly in the form of hematite and goethite phase. The favorable dielectric properties of iron oxide enable efficient microwave heating of red mud, and ~750 °C is achieved in 10 min with 10.7% C at 800 W. The heating rate in the mixture depends on the charcoal dosage and phase composition. The theoretical thermal decomposition kinetics suggest that the hematite to magnetite conversion in the red mud is chemically controlled and requires activation energy of 20.95 kJ/mol. The carbon gasification findings suggest that the CO formation is initiated below the bulk temperature of 700 °C during microwave heating, possibly because of accelerated microwave-induced heating in carbon having a significant effect on the reduction reaction mechanism. Volumetric heating enables efficient reduction and iron enrichment in magnetic concentrate with iron grade 52% and ~98% recovery constituting the magnetite phase majorly in 10 min, consuming 478.8 kJ energy. The iron metallization is dependent on the charcoal dosage, and ~15% metallic iron is formed in 30 min with 1435.4 kJ energy expenditure. The non-magnetic fraction is leached in 0.5 M HCl to recover alumina values in the mullite phase with an Al purity of 48% suitable for refractory applications. The non-magnetic residue containing iron values can be mixed with magnetic fraction to increase the Fe-product yield to ~84%.

Analyses of High‐Iron Sedimentary Bedrock and Diagenetic Features Observed With ChemCam at Vera Rubin Ridge, Gale Crater, Mars: Calibration and Characterization

AbstractCuriosity investigated a topographic rise named Vera Rubin Ridge (VRR) in Gale Crater, for which a distinct hematite‐like signature was observed from orbit. However, the Chemistry and Camera (ChemCam) and Alpha Particle x‐ray Spectrometer (APXS) instruments on board the rover did not record any significant iron enrichment in the bulk of the ridge compared to previous terrains. For this study, we have reverified ChemCam iron calibration at moderate abundances and developed more accurate calibrations at high‐iron abundances using iron‐oxide mixtures in a basaltic matrix in order to complete the ChemCam calibration database. The high‐iron calibration was first applied to the analysis of dark‐toned diagenetic features encountered at several locations on VRR, which showed that their chemical compositions are close to pure anhydrous iron oxides. Then, we tracked iron abundances in the VRR bedrock and demonstrated that although there is no overall iron enrichment in the bulk of the ridge (21.2 ± 1.8‐wt.% FeOT) compared to underlying terrains, the iron content is more variable in its upper section with areas of enhanced iron abundances in the bedrock (up to 26.6 ± 0.85‐wt.% FeOT). Since the observed variability in iron abundances does not conform to the stratigraphy, the involvement of diagenetic fluid circulation was likely. An in‐depth chemical study of these Fe‐rich rocks reveals that spatial gradients in redox potential (Eh) may have driven iron mobility and reactions that precipitated and accumulated iron oxides. We hypothesize that slightly reducing fluids were probably involved in transporting ferrous iron. Mobile Fe2+ could have precipitated as iron oxides in more oxidizing conditions.

The formation of marine red beds and iron cycling on the Mesoproterozoic North China Platform

Abstract Marine red beds (MRBs) are common in sedimentary records, but their genesis and environmental implications remain controversial. Genetic models proposed for MRBs variably invoke diagenetic or primary enrichments of iron, with vastly different implications for the redox state of the contemporaneous water column. The Xiamaling Formation (ca. 1.4 Ga) in the North China Platform hosts MRBs that offer insights into the iron cycling and redox conditions during the Mesoproterozoic Era. In the Xiamaling MRBs, well-preserved, nanometer-sized flaky hematite particles are randomly dispersed in the clay (illite) matrix, within the pressure shadow of rigid detrital grains. The presence of hematite flake aggregates with multiple face-to-edge (“cardhouse”) contacts indicates that the hematite particles were deposited as loosely bound, primary iron oxyhydroxide flocs. No greenalite or other ferrous iron precursor minerals have been identified in the MRBs. Early diagenetic ankerite concretions hosted in the MRBs show non-zero I/(Ca+Mg) values and positive Ce anomalies (&amp;gt;1.3), suggesting active redox cycling of iodine and manganese and therefore the presence of molecular oxygen in the porewater and likely in the water column during their formation. These observations support the hypothesis that iron oxyhydroxide precipitation occurred in moderately oxygenated marine waters above storm wave base (likely &amp;lt;100 m). Continentally sourced iron reactivated through microbial dissimilatory iron reduction, and distal hydrothermal fluids may have supplied Fe(II) for the iron oxyhydroxide precipitation. The accumulation of the Xiamaling MRBs may imply a slight increase of seawater oxygenation and the existence of long-lasting adjacent ferruginous water mass.

The importance of H2O in arc magmas for the formation of porphyry Cu deposits

Porphyry copper deposits (PCDs) hosted in subvolcanic intrusions at convergent margins are the primary world’s copper resources. However, the set of magmatic processes that lead to the generation of ore-bearing magmatic provinces remains unclear. In this paper we review the systematic of Cu evolution during arc magma differentiation using new and existing global compilations of whole rock geochemistry data. We trace the Cu evolution from primitive arc magmas through lower crustal plutonic to volcanic rocks. We focus on the well-known tholeiitic and calc-alkaline fractionation sequences, where arc tholeiitic series represents damp primitive melts (<2 wt% H2O) evolving with iron enrichment, and calc-alkaline series are wet primitive melts (>2 wt% H2O) that differentiate with iron depletion.Our study shows that the Cu concentration in primitive arc basalts (~80 ppm) is indistinguishable from that of primitive melts formed at mid-ocean ridges (MORBs) implying that Cu is mainly sourced from the mantle wedge in arcs with a limited contribution from the subducted oceanic lithosphere. A global compilation of plutonic rocks whole rock geochemistry (lower crustal cumulates and derivative melts) indicate no systematic difference in Cu concentrations between cumulates associated with tholeiitic or calc-alkaline series. Yet a complementary global compilation of arc volcanic whole rock geochemistry highlights the contrasting behavior of Cu in tholeiitic and calc-alkaline series during magmatic differentiation. In tholeiitic arc series, Cu shows an incompatible or compatible behavior during magma differentiation influenced by the crustal thickness. In calk-alkaline arc series, Cu is compatible during magma differentiation independently to the crustal thickness. This relates to the timing of sulfide saturation, which is controlled by the liquid lines of descent (LLD) and/or crustal thickness at redox conditions relevant for arc magmas.We demonstrate that the initial melt H2O content in primitive arc melts controls the LLD and the volume of remaining melt mass at fluid saturation. We show that the remaining H2O-saturated melt mass positively correlates with the total mass of Cu transferred into degassing fluids. The mass of extractable Cu ranges from ~3 to ~10 Mt (i.e., large PCD) for calc-alkaline series, and ranges from ~0.3 to ~2.5 Mt for tholeiitic series. The ore-forming potential of calc-alkaline arc magmas is at least ~4 to ~10 times higher relative to tholeiitic arc magmas. Despite the compatible behavior of Cu during magmatic differentiation, we propose that a single stage model for the formation of large economic PCDs (as opposed to multi-stage model for Cu-sulfides storage and remobilization) is most applicable for the calc-alkaline melts. The importance of the initial melt H2O content ultimately reflects the key role of flux melting associated with wet calc-alkaline series and high ore-forming potential, in opposition to decompression melting associated with damp tholeiitic series in arc.

Chemical fingerprints of formation in rocky super-Earths’ data

ABSTRACT The composition of rocky exoplanets in the context of stars’ composition provides important constraints to formation theories. In this study, we select a sample of exoplanets with mass and radius measurements with an uncertainty $\lt 25{{\ \rm per\ cent}}$ and obtain their interior structure. We calculate compositional markers, ratios of iron to magnesium and silicon, as well as core mass fractions (CMFs) that fit the planetary parameters, and compare them to the stars. We find four key results that successful planet formation theories need to predict: (1) In a population sense, the composition of rocky planets spans a wider range than stars. The stars’ Fe/Si distribution is close to a Gaussian distribution $1.63^{+0.91}_{-0.85}$, while the planets’ distribution peaks at lower values and has a longer tail, $1.15^{+1.43}_{-0.76}$. It is easier to see the discrepancy in CMF space, where primordial stellar composition is $0.32^{+0.14}_{-0.12}$, while rocky planets follow a broader distribution $0.24^{+0.33}_{-0.18}$. (2) We introduce uncompressed density ($\overline{\rho _0}$ at reference pressure/temperature) as a metric to compare compositions. With this, we find what seems to be the maximum iron enrichment that rocky planets attain during formation ($\overline{\rho _0}\sim 6$ and CMF ∼0.8). (3) Highly irradiated planets exhibit a large range of compositions. If these planets are the result of atmospheric evaporation, iron enrichment and perhaps depletion must happen before gas dispersal. And, (4) We identify a group of highly irradiated planets that, if rocky, would be twofold depleted in Fe/Si with respect to the stars. Without a reliable theory for forming iron-depleted planets, these are interesting targets for follow-up.

Eigen vector based analysis of Landsat OLI principal components and constrained energy minimization maps for discriminating iron enriched zones in banded iron formation (BIF) in Sidhi, Madhya Pradesh

In this study, we have used visible near infrared (VNIR) and shortwave infrared (SWIR) spectral bands of the Operational Land Imager (OLI) sensor of Landsat 8 satellite to delineate promising areas for iron exploration in the parts of Madhya Pradesh, India. OLI bands resampled laboratory reflectance spectra of Banded Iron Formation (BIF) were used as the reference to identify OLI spectral bands suitable in recording spectral features of Iron bearing minerals. Subsequently, BIFs were delineated in the principal component (PC) image prepared using those PC bands; which had opposite Eigen vector loading for the spectral bands; which recorded absorption minima and shoulder of the spectral feature of iron. Within the BIF, iron enriched zones were identified by integrating constrained energy minimization (CEM) maps of BIF, hematite and limonite-goethite. Integrated CEM map delineating iron enrichment zones was validated in the field based on measured Fe values of samples using X-ray Fluorescence Instrument.

Increased density of large low-velocity provinces recovered by seismologically constrained gravity inversion

Abstract. The nature and origin of the two large low-velocity provinces (LLVPs) in the lowest part of the mantle remain controversial. These structures have been interpreted as a purely thermal feature, accumulation of subducted oceanic lithosphere or a primordial zone of iron enrichment. Information regarding the density of the LLVPs would help to constrain a possible explanation. In this work, we perform a density inversion for the entire mantle, by constraining the geometry of potential density anomalies using tomographic vote maps. Vote maps describe the geometry of potential density anomalies according to their agreement with multiple seismic tomographies, hence not depending on a single representation. We use linear inversion and determine the regularization parameters using cross-validation. Two different input fields are used to study the sensitivity of the mantle density results to the treatment of the lithosphere. We find the best data fit is achieved if we assume that the lithosphere is in isostatic balance. The estimated densities obtained for the LLVPs are systematically positive density anomalies for the LLVPs in the lower 800–1000 km of the mantle, which would indicate a chemical component for the origin of the LLVPs. Both iron-enrichment and a mid-oceanic ridge basalt (MORB) contribution are in accordance with our data, but the required superadiabatic temperature anomalies for MORB would be close to 1000 K.

Mineralogical and geochemical characteristics of the iron–duricrust deposit in Adi-Daero area, northwestern Tigray, Ethiopia: implication for the origin and controlling factors

ABSTRACT Mineralogical and geochemical variations of elements from the Adi-Daero iron–duricrust were studied using petrographic, X–ray diffraction and geochemical analyses. Petrographic studies of the samples confirmed the presence of nodular and colloform textural features. The XRD analysis showed the presence of haematite, goethite, quartz, kaolinite and ilmenite are the mineral constituents. Major–element geochemistry was determined by ICP-AES, and trace and REEs were analysed using ICP-MS. Of the major oxides, Fe2O3 (6.8–72.93 wt-%) and SiO2 (11.07–77.75 wt-%) showed significant variation with generally increasing and decreasing trends from the iron-rich duricrust to the bedrock, respectively. In the profile studied, the alkali and alkaline earth elements (Ca, Mg, Na and K) were highly depleted, suggesting that iron–duricrust near–complete leaching. Elevated values of Sr and Ba in the lower part of the profile are probably due to their abundance in the protolith material (sandstone). A considerable enrichment of V and Cr, and Zr and REEs in the iron-rich duricrust and clay-rich horizon compared to the bedrock confirms their substitution for the Feoxyhydroxides, occurring in heavy mineral phases and adsorbed onto clay minerals, respectively. The La/Y <1 indicates an acidic environment in the upper part of the profile (AD-1 to AD-6; 0.64–0.99) and La/Y >1 a basic environment in the basal part of the profile (AD-7 to AD-12; 1.13–1.58). Similarly, the (La/Yb)N ratio of samples AD-1 to AD-6 (6.81–8.05) is significantly lower than that of AD-7 to AD–12 (10.09–24.54), reflecting an acidic environment. Positive Ce anomalies in the samples of AD-1 to AD-2 (1.17–1.2) are linked to the existence of cerianite due to change in oxidation state of Ce while in AD-8 and AD-9 (0.92–0.93), it is related to adsorption of Ce ions onto clay particles protolith. Therefore, the absolute enrichment of iron in the Adi-Daero iron–duricrust deposit was most likely an in situ process that involved vertical transfer from the iron-poor sandstone source rock.

Separation of silicon and iron in copper slag by carbothermic reduction-alkaline leaching process

Approximately 2.0–3.0 t of copper slag (CS) containing 35%–45% iron is generated for every ton of copper produced during the pyrometallurgical process from copper concentrate. Therefore, the recovery of iron from CS utilizes a valuable metal and alleviates the environmental stress caused by stockpile. In this paper, a new method has been developed to realize the enrichment of iron in CS through the selective removal of silica. The thermodynamic analyses and experimental results show that the iron in CS can be fully reduced into metallic iron by carbothermic reduction at 1473 K for 60 min. The silica was converted into free quartz solid solution (QSS) and cristobalite solid solution (CSS). QSS and CSS are readily soluble, whereas metallic iron is insoluble, in NaOH solution. Under optimal leaching conditions, a residue containing 87.32% iron is obtained by decreasing the silica content to 6.02% in the reduction roasted product. The zinc content in the residue is less than 0.05%. This study lays the foundation for the development of a new method to comprehensively extract silicon and iron in CS while avoiding the generation of secondary tailing.

No Redshift Evolution in the Broad-line-region Metallicity up to z = 7.54: Deep Near-infrared Spectroscopy of ULAS J1342+0928

Abstract We present deep (9 hr) Gemini-N/Gemini Near-InfraRed Spectrograph near-infrared spectroscopic observations of ULAS J1342+0928, a luminous quasar at z = 7.54. Various broad emission lines were detected, as well as the underlying continuum and iron forests over the rest-frame wavelength 970–2930 Å. There is a clear trend that higher-ionization emission lines show larger blueshifts with C iv exhibiting km s−1 blueshift with respect to the systematic redshift from the far-infrared [C ii] emission line. Those high-ionization lines have wide profiles with FWHM more than 10,000 km s−1. A modest blueshift of km s−1 is also seen in Mg ii, the lowest-ionization line identified in the spectrum. The updated Mg ii-based black hole mass of and the Eddington ratio of confirm that ULAS J1342+0928 is powered by a massive and actively accreting black hole. There is no significant difference in the emission-line ratios such as Si iv/C iv and Al iii/C iv when compared to lower-redshift quasars in a similar luminosity range, which suggests early metal pollution of the broad-line-region clouds. This trend also holds for the Fe ii/Mg ii line ratio, known as a cosmic clock that traces the iron enrichment in the early universe. Different iron templates and continuum fitting ranges were used to explore how the Fe ii/Mg ii measurement changes as a function of spectral modeling. Quasars at even higher redshift or at fainter luminosity range ( erg s−1) are needed to probe the sites of early metal enrichment and a corresponding change in the Fe ii/Mg ii ratio.

The Ediacaran post-collisional Khamal gabbro-anorthosite complex from the Arabian Shield and its Fe-Ti-P ore: An analogy to Proterozoic massif-type anorthosites

The Khamal complex is an Ediacaran post-collisional gabbro-anorthosite igneous complex that intruded Tonian and Cryogenian subduction-related island arc and ophiolitic rocks and syn-tectonic granitic rocks. The complex is reminiscent of massif-type anorthosites. It has an elliptical shape and is unmetamorphosed and undeformed. The Khamal complex is differentiated into four lithological units, marginal gabbro, anorthosite, central gabbro and northern gabbro. Anorthosite is the most dominant unit and is surrounded by marginal high-Al (Al2O3 >16 wt%) gabbro and gabbronorite showing a positive Eu anomaly. Iron-rich gabbroic rocks associated with nelsonite (Fe-Ti-P ore) and magnetite-ilmenite (FeTi ore) are exposed in the central portion of the anorthosite. Towards the north, less differentiated massive gabbronorite is exposed, which is characterized by its high Al2O3 contents in addition to the MgO contents. The association between anorthosite and AlFe mafic melts is recorded in several Proterozoic massif-type anorthosite complexes. The formation of the Khamal gabbro-anorthosite complex was most likely related to the waning stage of the East African orogeny. After the assembly of the Tonian-Cryogenian island arc terranes, slab break-off and lithospheric delamination induced asthenospheric upwelling and ponding of the mafic melt at the crust-mantle boundary. The resulting mantle-derived or lower crustal melt evolved, which led to the formation of floated plagioclase. Then, the plagioclase-rich diapir ascended to form the anorthosite and high-Al marginal gabbroic rocks. The less differentiated high-Al gabbronorite of the northern unit intruding the anorthosite mimics its parental magma but does not directly represent the magma from which anorthosite crystallized. The central gabbroic unit is characterized by an enrichment in iron. This unit might represent the residual melt that was extracted and segregated into a small chamber from the anorthosite, which was emplaced in a dynamic environment. In this chamber the melt underwent further crystal fractionation and accumulation processes. The compositional gap between the nelsonite and magnetite-ilmenite ores and the enclosing gabbroic rocks as well as the similarity between these ores and the host gabbro and the discordant nature of the FeTi ore favor the immiscibility origin of the ore.

Effects of Replacing Inorganic with Organic Iron on Performance, Egg Quality, Serum and Egg Yolk Lipids, Antioxidant Status, and Iron Accumulation in Eggs of Laying Hens.

This study compared the effects dietary organic (ferrous glycine [FG]) versus inorganic (ferrous sulfate [FS]) iron in laying hens on performance, egg quality, serum and egg yolk lipids, antioxidant status, and iron enrichment of eggs. A total of 378 Shaver White layers were allotted to 7 treatments with 6 replicates (9 birds each) from 30 to 42weeks of age. A basal diet (19mg iron/kg) served as control, while the other six diets were supplemented with either FS or FG to provide 30, 60, and 120mg/kg of added iron. Dietary FG and FS treatments improved (P < 0.05) laying rate, egg weight, and egg quality of layers, relative to the control, albeit eggshell strength and eggshell calcium also deteriorated with the highest level of FS (P< 0.05). The iron treatment groups exhibited a lower serum and egg yolk levels of triglycerides, total cholesterol, and low-density lipoprotein cholesterol that accompanied by higher levels of high-density lipoprotein cholesterol and greater activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) as compared with the control (P < 0.05). The contents of malondialdehyde and protein carbonyl were conversely related to the activities SOD and GPx (P < 0.05). The serum and egg fractions (yolk, albumen, and shell) displayed gradually increases in iron contents as the level of iron increased in the diet (P < 0.05), while FG was superior to FS at all tested levels (P < 0.05). To summary, FS can be replaced by FG, with more favorable impacts on egg quality and iron enrichment.

Individual enrichment of manganese and iron from complex refractory ferromanganese ore by suspension magnetization roasting and magnetic separation

Owing to its complex characteristics, the large-scale utilization of ferromanganese ore is limited by the traditional processes. In this study, suspension magnetization roasting and magnetic separation technology was proposed, and the thermodynamics, phase and magnetic transformation, and microstructure evolution of the main minerals were systematically investigated during roasting. Results show that iron concentrate with iron grade of 68.31% at a recovery of 96.34% can be obtained in the magnetic separation concentrate, and manganese concentrate with manganese grade of 33.70% at a recovery of 86.83% can be obtained in magnetic separation tailings under optimum conditions. Pyrolusite and braunite were reduced to weak magnetic manganosite, and weak magnetic hematite was selectively transformed into strong magnetic magnetite. Many cracks appeared in the ores owing to the multiple reduction and dehydration reactions of ferromanganese ore, which was favorable for grinding and separation of manganese and iron.