Mineral Element Composition Research Articles

Investigating the application of Raman spectroscopy of carbonaceous material in sedimentary lithic artifacts for archaeological provenancing applications in the Canadian Rockies

AbstractThe chemical compositions of toolstones composed of clastic and chemical sedimentary rock are often not distinct among procurement locations. However, sedimentary toolstone sources may show variations in the structural characteristics of the included carbonaceous material (CM) related to differences in their postdepositional histories, providing a potential proxy by which procurement locations, rather than individual rock units, can be assessed as raw material sources for archaeological lithics. Here, we apply a well‐established method for investigating the nature of CM in sedimentary rocks, Raman spectroscopy of carbonaceous material (RSCM), to an archaeological case study. We test if the technique can be used to differentiate among toolstones from two procurement areas along the eastern slopes of the Canadian Rocky Mountains potentially used by pre‐European contact Indigenous inhabitants of the Hummingbird Creek Site (FaPx‐1). Artifacts found during excavations at Hummingbird Creek visually appear to match toolstone‐grade rocks in the site's vicinity. We analyzed source material from two localities: (1) the local toolstone around FaPx‐1 and (2) a toolstone procurement area ~45 km away associated with many precontact workshop sites. To test if the artifacts have compositions consistent with the local toolstones, we analyzed artifacts and potential source materials with RSCM as well as their major, minor, and trace element composition using X‐ray fluorescence (XRF). Our work is guided by the elimination of source locations using indirect geochemical proxies in accordance with the exclusionary Provenance Hypothesis. Both the structural and the chemical characteristics of the artifacts are similar to those of geologic samples from the nonlocal source location and are not consistent with samples collected locally, permitting the exclusion of local materials and suggesting that the inhabitants of FaPx‐1 used a variety of toolstones to manufacture the artifacts from materials that do not appear to be readily available near the site.

An energy dispersive X-ray fluorescence spectrometry approach for the identification of geographical origin of wheat flour

Abstract In this work, a method was established for discriminating geographical origins of wheat flour based on energy dispersive X-ray fluorescence spectrometry (ED-XRF) and chemometrics. 68 wheat flour samples from three different origins were collected and analyzed using ED-XRF technology. Firstly, the principal component analysis method was applied to analyze the feasibility of discrimination and reduce data dimensionality. Then, Competitive Adaptive Reweighted Sampling (CARS) was used to further extract feature variables, and 12 energy variables (corresponding to mineral elements) were identified and selected to characterize the geographical attributes of wheat flour samples. Finally, a non-linear model was constructed using principal component analysis and quadratic discriminant analysis (QDA). The CARS-PCA-QDA model showed that the accuracy of five-fold cross-validation was 84.25%. The results showed that the established method was able to select important energy channel variables effectively and wheat flour could be classified based on geographical origins with chemometrics, which could provide a theoretical basis for unveiling the relationship between mineral element composition and wheat origin.

Petrogenesis of the Tampanchi Ultramafic–Mafic Complex (Ecuador): Geodynamic implications for the northwestern margin of South America during the late Cretaceous

The Tampanchi Ultramafic–Mafic Complex (TUMC), located in the central segment of the Cordillera Real (Ecuador), is an oval-shaped intrusive body of approximately 18 km2 emplaced within a Cretaceous metavolcano-sedimentary sequence. Field investigations, zircon geochronology, mineral and whole-rock elemental and isotopic compositions constrain the nature of the parental magma as well as the physical conditions of emplacement, age of crystallization and tectonic setting of formation of the TUMC. The Complex consist of wehrlite and olivine-hornblende clinopyroxenite crosscut by hornblende gabbros and minor dikes/veins of diorite and granite. Hornblendites formed mainly at the contact between the olivine-hornblende clinopyroxenite and the intrusive hornblende gabbros by reaction-replacement processes. Geochemical data for both the wehrlites and pyroxenites define a trend with dominantly olivine and clinopyroxene accumulation, whereas a second trend is formed by hornblende gabbros that differentiated to leucocratic rocks, with amphibole as the dominant fractionating mafic phase. The trace elements show enrichment in large-ion lithophile elements, depletion in high field strength elements (Nb, Zr, Ti) and P, and enrichment in Pb, Sr and Ba relative to primitive mantle, indicating subduction-related parental liquids. The Nd and Sr isotopic composition suggests a uniform mantle source metasomatized by subducted crustal components. Thermobarometric estimations constrain emplacement and crystallization at intermediate to shallow continental crust levels (∼12.5 km depth) of hydrated basaltic melt under oxygen fugacity conditions above the nickel-nickel oxide buffer (ΔNNO = 0 to 2). Zircon SHRIMP U-Th-Pb age data constrain crystallization at 75.1–76.0 Ma, with scarce inherited zircons that record limited recycling of the Cordillera Real basement. These results confirm magmatic arc activity at the continental margin of South America during the late Cretaceous as a result of an E-dipping subduction zone prior to the accretion of the Ecuadorian-Colombian-Caribbean oceanic plateau, and support simultaneous double subduction at the northwest margin of South America during the Cretaceous.

Magma evolution and Cu-Au mineralization potential of the Upper Devonian-Lower Carboniferous Tulasu basin, Western Tianshan Orogen (NW China): Apatite U-Pb dating and geochemical perspectives

The large Axi low-sulfidation epithermal gold deposit (reserve: 50 tonnes Au) is one of the most important gold deposits in the Tulasu basin (Western Tianshan Orogen, NW China), and is hosted by the Upper Devonian-Lower Carboniferous Dahalajunshan Formation volcanic rocks. Due to the close relationship between the genesis and spatial distribution of epithermal gold and porphyry copper deposits, whether the latter is buried beneath the Tulasu basin is highly debated.In this study, apatite and zircon grains from nine ore-hosting volcanic rocks were LA-ICPMS U-Pb dated and analyzed for their minor and trace element compositions. Zircon U-Pb dating suggests multiphase magmatism, with the main phase at ca. 370 and 360 Ma. Apatite U-Pb dating results are consistent with those of zircon U-Pb dating and previous zircon dating works (ca. 380 to 350 Ma), demonstrating the accuracy of apatite U-Pb dating. The apatite Cl content varies with age, which shows that it has the potential to record Cl replenishment from the subducting slab into the mantle wedge. Compared with the apatite Cl content from porphyry Cu deposits worldwide, the apatite Cl content from Axi is much (1–2 wt%) lower, suggesting low potential in forming porphyry copper deposits.

A New Quantitative Approach for Element-Mineral Determination Based on “EDS (Energy Dispersive Spectroscopy) Method”

With the continuous development of hydrocarbon exploration, how to efficiently, economically, accurately, and comprehensively obtain mineral species, composition, and structure and diagenesis information has become one of the hot topics in both the academia and industry. By scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), a new method of qualitative mineral identification and quantitative measurement is established. Typical tight sandstone reservoir rock samples in the Ordos Basin are selected; through the element surface scanning image of “mineral element composition” and “pixel element combination”, mineral types are distinguished, and mineral parameters such as types, characteristics, and content are rapidly and accurately determined. Meanwhile, such results achieved via the new method are compared with conventional XRD and TIMA methods. The results show that the new method exhibits several advantages: cost advantages compared to XRD experiment analysis technology and TIMA system and ability to analyze low content minerals which XRD techniques are hard to identify; it allows quantitative characterization on the phenomenon of mineral miscibility, which is of great significance to explore the mineral diagenetic evolution.

Phytochemical evaluation and health risk assessment of honey from an Apiary in Amizi, Ikuano local government area, Abia State, Nigeria

The phytochemical and mineral element compositions of honey from an apiary in Amizi community, Abia State, Nigeria were determined and possible health risks as a result of the presence and concentration of the identified mineral elements assessed. The most abundant phytochemicals in the honey samples were phenols, sapogenin, sparteine, lunamarin, flavanone, and proanthocyanin, with mean concentrations 102.53 µg/g, 81.40 µg/, 58.92 µg/g, 42.84 µg/g, 36.14 µg/g and 27.56 µg/g respectively. The concentration of iron, nickel, copper, zinc, and lead were 17.60 ± 3.68, 6.40 ± 0.48, 5.60 ± 0.88, 15.80 ± 3.84, and 1.20 ±0.32 mg/kg respectively. The health risk assessment showed that lead, nickel, aluminum, copper, and zinc in the honey samples did not pose non-carcinogenic risk to the health of the consumers. However, the carcinogenic risk of nickel was found to be 1.64(-3) which exceeded the acceptable level of 10(-4). This finding indicated that the consumption of this honey could pose a potential cancer risk to its consumers. Regulatory agencies in all countries should, therefore, introduce mandatory regulations and laws that would control honey production, handling, and quality check to ascertain its safety level.

Proximate Composition, In vitro Antioxidant and Anti-inflammatory Properties of Adansonia digitata and Belanites aegyptiaca Seeds

This study evaluated the nutritional and medicinal properties of seeds from Adansonia digitata (BSF) and Balanite aegyptiaca (DDSF) plant. Proximate chemical composition, mineral elements composition, flavonoids, phenolics, antioxidant capacity, and anti-inflammatory properties were studied. Results obtained revealed that DDSF had the highest moisture, crude fat and crude protein content of 7.66 %, 42.80 %, 20.37 % respectively, whilst BSF gave the highest ash, crude fibre and carbohydrate content. Elemental analysis revealed BSF had the highest Mg content (313.65 mg/100g) and DDSF gave the highest Ca content (118.62 mg/100g). Additionally, DDSF gave the highest total phenolics (18.89 mg TAE/ 100 g), total flavonoids (8.80 mg QE/ 100 g) as well as the highest total antioxidant capacity of (19.62 mg AAE/ 100 g) dry of extract. Based on results obtained in this study, seeds obtained from the Adansonia digitata and Balanite aegyptiaca could be a potential source of functional food and antioxidant agents.

Aspects of pharmacognostic evaluation of the herbs for a traditional antimalarial (maloff-hb) powdered formulation in ogbomoso, Nigeria

Maloff-HB is a documented traditional oral powdered herbal drug in Ogbomoso, Nigeria whose botanical constituents, ascorbic acid and mineral elements composition have been quantified but there is inadequate information on the pharmacognostic properties of the nine herbal materials for its formulation. This study therefore sought to elucidate the bark and wood anatomy of eight of the nine herbs used in the formulation, and identify the diagnostic markers for their authentication. The conventional anatomical techniques of transverse sectioning (TS) and tissue maceration (TIM) were used to draw out 21 characteristics from the root barks of the eight woody species studied. In addition, 41 features of the wood in the roots of three of the species were drawn using TS, transverse longitudinal sectioning (TLS), radial longitudinal sectioning (RLS) and TIM. Following staining, mounting and microscopic examinations, the observed qualitative and quantitative features were taxonomically described in accordance with the provisions of International Association of Wood Anatomists, and their diagnostic values among the medicinal herbs were explored. Bark anatomical markers that are clearly diagnostic of the species studied included features of the secondary cortex, phloem rays, axial parenchyma, sclereids and resin ducts. In the wood, these included features of the vessels in the TS and variable ray characteristics in the TLS. The two artificial keys obtained from discontinuities in qualitative and quantitative features observed in the barks and the woods are useful tools for reliable identification of the herbal materials studied.

Evaluation of some pharmacognostic parameters of the herbs for a traditional hematinic (Haematol -B) powdered formulation in Ogbomoso, Nigeria

The traditional hematinic oral powdered herbal drug (Haematol-B) from Ogbomoso, Nigeria had been characterized in terms of its botanical constituents, ascorbic acid and mineral elements composition, but there is inadequate information on the pharmacognostic properties of the ten herbal materials for its formulation. Therefore the objective of this study was to evaluatethe bark and wood anatomy (as appropriate) of seven of these herbs with a view to highlighting the diagnostic markers for their authentication. Following the conventional anatomical procedures of transverse sectioning (TS) and tissue maceration (TIM), a total of 21 characters were drawn from the barks (root or stem as appropriate) of the seven woody species studied, while 41 characteristics of the wood in the roots of three of the species were compiled using TS, transverse longitudinal sectioning (TLS), radial longitudinal sectioning (RLS) and TIM techniques. Staining, mounting and microscopic examinations followed, and the observed features were taxonomically described in accordance with the provisions of International Association of Wood Anatomists. Their diagnostic values among the medicinal herbs studied were also explored. The bark anatomical features that can be used to diagnose the species studied were those of the secondary cortex, phloem rays, axial parenchyma, sclereids and resin ducts. The wood anatomical markers included features of the vessels in the TS and variable ray characteristics in the TLS. The two artificial keys constructed from discontinuities in qualitative and quantitative anatomical features of the barks and the wood are useful tools for avoiding misidentification of the herbal materials studied.

Effects of nanosilicon dioxide on leaf anatomy, chlorophyll fluorescence, and mineral element composition of strawberry under salinity stress

Leaf morphology and anatomy are important criteria to evaluate plant tolerance to salinity stress. Therefore, in this study the morphophysiological responses of strawberry (Fragaria’× anansa Duchesne “Camarosa”) plants treated with nanosilicon (nSiO2) were investigated under salt-stress conditions. The plants in a complete nutrient solution designed for strawberry were exposed to salt stress (0, 25, or 50 mM NaCl) and treated with nanosilicon before (0, 50, or 100 mg L−1) or after (0 or 50 mg L−1) floweringConcentrations of sodium (Na), chlorine (Cl), and calcium (Ca) increased in plants exposed to salt stress, whereas silicon (Si), potassium (K), and phosphorus (P) decreased. In the presence of nanosilicon, strawberry plants absorbed K, P, and Ca from the nutrient solution and transferred the nutrients to leaves effectively. Only a little amount of Ca, Cl, or Na was transferred to leaves with presence of nanosilicon. The adverse effects of salinity on phyllochron, flowering, and fruit set, and fruit production parameters were suppressed by application of nanosilicon. Analysis by optical microscopy revealed that salt stress limited the number of parenchyma cells, leaf thickness, epidermis cell thickness, and mesophyll thickness, thereby leading to restrictions in chlorophyll content and photosynthetic efficiency. Nanosilicon application reduced negative effects of salinity by improving cell wall thickness, providing higher content of water, and leading to increased chlorophyll content and fluorescence. Overall, these observations indicated that application of nanosilicon can suppress the adverse effect of salinity on anatomical and physiological changes of strawberry plants.

Podiform magnetite ore(s) in the Sabzevar ophiolite (NE Iran): oceanic hydrothermal alteration of a chromite deposit

Serpentinite-hosted massive magnetite ore bodies are reported for the first time in the Late Cretaceous Sabzevar ophiolitic belt, northeastern Iran. They show irregular and discontinuous shapes with variable sizes ranging from 30 to 60 cm. Chromian spinel grains are observed within both magnetite ores and host serpentinite. Magmatic chromian spinels, (Cr,Al)-spinel I, with compositions close to (Mg0.6,Fe0.4)(Cr1.2,Al0.75,Fe3+0.05)O4 are preserved in the host serpentinite where they display a porous alteration rim composed of Cr-bearing chlorite and three different spinel-structure minerals: Cr-spinel (Fe0.6,Mg0.4)(Cr1.4,Al0.4,Fe3+0.2)O4, named Cr-spinel II (second generation), magnetite and ferritchromite, nominally FeCr2O4. In the magnetite ore body, no (Cr,Al)-spinel I is found and Cr-spinel II occurs as relict cores surrounded by ferritchromite and magnetite. Detailed X-ray elemental mapping revealed that the 200 μm-thick magnetite rim is composed of two magnetite types with different minor element compositions: the first rim found at the contact with ferritchromite is thin (20 μm; magnetite-I); the thicker outer rim contains numerous Fe-poor and Mg- and Si-rich silicate inclusions (magnetite-II). Observations at the TEM scale allows to identify ferritchromite which occurs as a micrometer-sized rim between Cr-spinel II and magnetite I. Thermodynamic modelling of the phase relationships in the studied Sabzevar serpentinite suggests that Cr-spinel II is produced along with chlorite during a first alteration stage at temperatures between 725 and 575 °C in the course of peridotite-water interactions. A second hydrothermal alteration stage producing ferritchromite and magnetite is inferred from the thermochemical modelling at temperatures < 400 °C under high H2 fugacity. This latter stage corresponds to the serpentinization of the Sabzevar oceanic peridotite and associated podiform chromitite deposit. The two alteration stages are interpreted as the result of the interaction between seawater and oceanic mantle at two different depth ranges in the course of its exhumation. Our thermodynamic calculations and textural relationships revealed that Cr is immobile and Fe is the main element to be transferred to the magnetite ore during alteration processes. Fe possibly originated from direct transport of the Fe2+ produced during olivine dissolution or from the dissolution of nano-sized magnetite grains initially formed in the host serpentinite during early serpentinization. Mass balance calculation reveals significant iron transport at a scale > 10 m during serpentinization.

ICP-MS based analysis of mineral elements composition during fruit development in Capsicum germplasm

Capsicum fruits are rich sources of mineral nutrients with several health benefits. However, a thorough investigation of mineral elements in Capsicum fruits at green, breaker and mature developmental stages in comparatively larger germplasm has not been reported yet. This study reports profiling of 9 mineral elements i.e. Mg, P, K, Ca, B, Mn, Fe, Cu and Zn in 20 Capsicum accessions belonging to Capsicum annuum, C. chinense and C. frutescens from Northeast India. Briefly, the highest content of P (1798 ± 39) and K (7560 ± 76 mg 100g−1) at the green and breaker stages of Capsicum accession Acc-Ca9, Fe (13 ± 2) and Zn (4 ± 0.1) at the breaker stage of Acc-Ca2; and Cu at the mature stage of Acc-Cc2 (3 ± 0.4) and Acc-Cc3 (3.4 ± 0.04 mg 100g−1) were observed and showed significant differences (p < 0.001) between the developmental stages. Overall, with fruit maturation, the K content increased in C. frutescens while K and P content decreased in C. chinense and C. annuum. Statistical analysis showed significant correlations (p < 0.01) among mineral elements in the three fruit development stages. The data from this study suggests that accessions having high mineral content can be used as rich sources of dietary mineral nutrients and potential donors for biofortification of Capsicum crops.

Fertilizing behavior of extract of organomineral-activated biochar: low-dose foliar application for promoting lettuce growth

BackgroundFostering plant growth and improving agricultural yields by adding “macro”-sized biochar to soil has been extensively explored. However, the impact and mechanism of action of aqueous extracts of biochar applied as foliar fertilizer on plant growth and physiology is poorly understood, and was the objective of this study. Extracts were produced from biochars derived from pine wood:clay:sand (PCS-BC; 70:15:15) and wheat straw:bird manure (WB-BC; 50:50) and tested at two dilutions each. The plant influence of the biochar extracts and dilutions were compared with chemical fertilizer made up to the same minor trace element compositions as the applied extracts and a control treatment consisting of only deionized water.ResultsThe WB-BC extract was more alkaline than the PCS-BC extract and exhibited higher electrical conductivity values. Similar to the biochars from which they were derived, the WB-BC extract had higher concentrations of dissolved mineral elements and organic matter than the PCS-BC extract. Despite major differences in chemical composition between the PCS-BC and WB-BC extracts, there was virtually no difference in plant performance between them at any chosen dilution. Foliar application of PCS25, WB50, and WB100 led to a significant increase in the plant fresh biomass in comparison to their corresponding chemical fertilizer and to deionized water. Plant growth parameters including number of leaves and chlorophyll contents in plants treated with biochar extract foliar sprays were significantly higher than in all the other treatments. Electron microscopy and spectroscopy studies showed the deposition of macro- and nanoscale organomineral particles and agglomerates on leaf surfaces of the examined PCS25-treated plant. Detailed study suggests that carbon nanomaterials and TiO2 or Si-rich nanoscale organomineral complexes or aluminosilicate compounds from biochar extract were main contributors to increased plant growth and improved plant performance.ConclusionThese results suggest that biochar extracts have the potential to be used as nanofertilizer foliar sprays for enhancing plant growth and yield.

Variation of Chemical Components in Sapwood, Transition Zone, and Heartwood of Dalbergia odorifera and Its Relationship with Heartwood Formation

Heartwood has a high economic value because of its natural durability, beautiful color, special aroma, and richness in active ingredients used in traditional Chinese medicine. However, the mechanism of heartwood formation remains unclear. Dalbergia odorifera was selected as the object of research to analyze this variation in the chemical composition of sapwood, transition zone, and heartwood as well as to elucidate the relationship between this variation and the formation of heartwood. The variation of secondary metabolites was analyzed using gas chromatography-mass spectrometry and ultra-high performance liquid chromatography–mass spectrometry, the variation of lignin was analyzed using Fourier transform infrared spectroscopy and ultraviolet visible spectrophotometry, and the variation law of mineral elements was analyzed using atomic absorption spectrophotometry. The results demonstrated that contents of characteristic secondary metabolites in Dalbergia odorifera were mainly distributed in heartwood (84.3–96.8%), increased from the outer to inner layers of the xylem, and sudden changes occurred in the transition zone (the fourth growth ring). The Dalbergia odorifera lignin can be identified as typical “syringyl–guaiacyl (S–G)” lignin, and the color darkened from the outside to the inside. The results demonstrated that there were more benzene rings and conjugated C=O structures in the heartwood. Additionally, the variation of minerals in the xylem was related to elemental types; the average concentrations of Mg, Ca, Fe and Sr were higher in the heartwood than in the sapwood, whereas the concentrations of K and Zn were higher in the sapwood than in the heartwood owing to the reabsorption of elements. The concentrations of Na and Cu were similar in the heartwood and sapwood. The composition and structural characteristics of secondary metabolites, lignin, and mineral elements in the three typical xylem regions (sapwood, transition zone and heartwood) of Dalbergia odorifera changed. The most abrupt change occurred in the narrow xylem transition zone, which is the key location involved in heartwood formation in Dalbergia odorifera.

Tracing mantle source variation through xenocrystic olivine in the Taupo Volcanic Zone, New Zealand: A role for lithospheric mantle in the shift from andesitic to rhyolitic compositions

The central Taupo Volcanic Zone (TVZ) in New Zealand, the most productive of silicic volcanic centres, is flanked by younger andesitic stratovolcanoes to the south. Small basaltic scoria cones occur along the length of the TVZ, the most primitive of which contain abundant xenocrysts, giving insight into the mantle feeding the TVZ.Here, we present major and minor element compositions of olivine from eleven mafic eruptions spanning the length of the central and south TVZ. Olivine compositions can be divided into three major groups, based on their texture, major and minor element composition, and zoning. Group 1 olivines are Fo88 in the most primitive cores, with minor element concentrations consistent with magmatic origin. Group 2 olivine compositions range from Fo72–88 but are homogeneous within individual crystals. CaO contents are consistently lower for a given forsterite content compared to group 1 olivines and are most consistent with a plutonic crystal mush origin. Group 3 olivines have core compositions of Fo93–90, and NiO and CaO (0.36–0.56 wt%, <0.15 wt%, respectively) concentrations consistent with a primary magma or mantle-derived origin. Compositional variation within group 3 olivine allows for further characterisation of the mantle lithologies from which the crystals were sourced. Group 3 olivines from the central TVZ are lherzolite-derived, whereas group 3 olivines from the south TVZ are harzburgite-derived. However, recent whole-rock and melt inclusion data suggests that the most fertile mantle underlies the south TVZ, and the least fertile mantle underlies the inter-caldera regions of the central TVZ where caldera-forming volcanism has ceased. This is inconsistent with interpretations drawn from the olivine data. We therefore suggest that harzburgitic xenocrysts originate from old depleted sub-continental lithospheric mantle (SCLM), which is present at depths of ~30 km in the south TVZ. By contrast, rifting and crustal thinning in the central TVZ has removed the SCLM, explaining why only xenocrysts of lherzolitic origin are found. The presence of depleted SCLM may act as a boundary layer inhibiting ascent of melt from the mantle, providing an explanation for lower erupted volumes in the south TVZ. Dissolution of the orthopyroxene component in harzburgite in the presence of hydrous melt satisfies major element constraints on south TVZ basalt (high SiO2, high MgO, low CaO/Al2O3). Taken together, this is the first mineralogical evidence for a tectonic and lithospheric control on the shift from andesitic to rhyolitic activity in the TVZ, implying a direct link between rifting, magma composition and volcanic productivity.

Lithospheric mantle refertilization by DMM-derived melts beneath the Cameroon Volcanic Line\u2014a case study of the Befang xenolith suite (Oku Volcanic Group, Cameroon)

The origin and evolution of subcontinental lithospheric mantle (SCLM) are important issues of Earth’s chemical and physical evolution. Here, we report detailed textural and chemical analyses on a mantle xenolith suite from Befang (Oku Volcanic Group, Cameroon Volcanic Line), which represents a major tectono-magmatic structure of the African plate. The samples are sourced from spinel-facies mantle and are dominated by lherzolites. Their texture is cataclastic to porphyroclastic, and foliation defined by grain-size variation and alignment of spinel occurs in part of peridotites. Spinel is interstitial and has amoeboidal shape. Clinopyroxene REE patterns are similar to those of Depleted MORB Mantle (DMM) except LREEs, which vary from depleted to enriched. The A-type olivine fabric occurs in the subset of one harzburgite and 7 lherzolites studied by EBSD. Orthopyroxene shows deformation consistent with olivine. The fabric of LREE-enriched clinopyroxene is equivalent to those of orthopyroxene and olivine, whereas spinel and LREE-depleted clinopyroxene are oriented independently of host rock fabric. The textural, chemical and thermobarometric constraints indicate that the Befang mantle section was refertilised by MORB-like melt at pressures of 1.0–1.4 GPa and temperatures slightly above 1200–1275 °C. The olivine-orthopyroxene framework and LREE-enriched clinopyroxene preserve the protolith fabric. In contrast, the LREE-depleted clinopyroxene, showing discordant deformation relative to the olivine-orthopyroxene protolith framework, and amoeboidal spinel crystallized from the infiltrating melt. The major element and REEs composition of minerals forming the Befang peridotites indicate subsequent reequilibration at temperatures 930–1000 °C. This was followed by the formation of websterite veins in the lithospheric mantle, which can be linked to Cenozoic volcanism in the Cameroon Volcanic Line that also brought the xenoliths to the surface. This study therefore supports the origin of fertile SCLM via refertilization rather than by extraction of small melt fractions, and further emphasizes the involvement of depleted melts in this process.

In situ Si isotope and chemical constraints on formation and processing of chondrules in the Allende meteorite

Chondrules in undifferentiated meteorites are former silicate melt droplets of variable texture and composition. Although widely studied, the chondrule formation mechanisms and conditions that explain all properties of chondrules are yet to be identified. To further constrain the processes that affected chondrules in the solar nebula and on the meteorite parent body, we determined in situ Si isotope ratios and major and trace element compositions of minerals in chondrules of variable types and sizes from the Allende CV3 chondrite.The δ30Si in chondrule minerals ranges from −1.28 ± 0.19 to 0.55 ± 0.20‰ (2SE). The δ30Si in chondrules shows no direct relationship with chondrule sizes or with distance between core and rim. Barred olivine-rich chondrules record the highest δ30Si, likely because of faster cooling and less interaction with isotopically light nebular gas. Type I non-porphyritic and some porphyritic chondrules show overall higher δ30Si compared to type II porphyritic chondrules. Furthermore, Mg-rich olivine and Mg-rich pyroxene have systematically higher δ30Si compared to Fe-rich olivine and Fe-rich pyroxene.The variable δ30Si of type I chondrule silicates (Mg-rich) compared to type II chondrule silicates (Fe-rich) may be explained by variable interaction of chondrule silicates with the nebular gas in the solar nebula. We envision a combination of equilibrium and kinetic isotope fractionation of Si between nebular gas and Fe-poor silicates (such as forsterite, anorthite, enstatite and mesostasis) and Fe-rich olivine and orthopyroxene. Petrographic evidence suggests that the enrichment of Fe in some highly altered porphyritic chondrules and at chondrule rims was likely caused by hydrothermal alteration on the parent body. Therefore, the correlation of Fe and δ30Si of the chondrule minerals might serve as an indicator for the extent of further secondary processing of some chondrule minerals. The sum of these observations suggests that the formation and alteration of type II chondrules occurred by oxidation of originally reduced, metal-rich type I chondrules, both in the solar nebula and later on the meteorite parent body. Remaining 30Si depleted gas contributed to the isotopic composition of matrix silicates. The evidence favours the formation of chondrules and matrix of the Allende meteorite in nebular settings rather than by asteroid impacts.

Geophagic clay around Uteh-Uzalla near Benin: mineral and trace elements compositions and possible health implications

Geophagic clay consumption, which is an age-long cultural practice by humans and animals in many parts of the world, and particularly in Nigeria, may have long time health effects on the consumers. This is particularly so because of the relatively high concentration of harmful minerals and toxic elements. This study sought to determine the mineralogical and trace element compositions of geophagic clay in Uteh-Uzalla area, which is underlain by the Benin Formation of Oligocene to Miocene age, in order to evaluate the potential health risk associated with the consumption of the clay. Sixteen clay samples were collected from mine face profiles of an open pit, analysed for mineral and trace element compositions, using x-ray diffraction technique and ultra-trace inductively coupled plasma mass spectrometry (ICP-MS) methods, respectively. The mean mineral concentration in % includes kaolinite, quartz and smectite (64.88, 19.98, and 9.54), respectively, among other minerals. And the mean concentrations in mg/kg for Cu (15.0), Pb (14.4), Zn (30.9), Co (8.9), Mn (39.4) and Th (10.5) among other elements were found in the clay. From the trace elements results when compared with health risk indices by Agency for Toxic Substances and Diseases Registry (ATSDR): Minimum Risk Level, recommended daily intake and estimated daily intake, it was found that the elements are far above the daily oral intake requirement. Also, considering the relatively low pH (acidic) values that were exhibited by the clays, harmful minerals and elements contained in the clay may be bioavailable in the internal system among those who are frequently involved in the consumption of the clay.

The chromitites of the Neoproterozoic Bou Azzer ophiolite (central Anti-Atlas, Morocco) revisited

• Intermediate-Cr and high-Cr chromitites in the Bou Azzer ophiolite, Morocco. • Chromitites crystallized from fore-arc basalts (FAB) and boninites, respectively. • Fore-arc position of the ophiolite in a subduction-initiation geodynamic setting. • Super-reduced phases (moissanite and native Cu) formed during serpentinization. The Neoproterozoic Bou Azzer ophiolite in the Moroccan Anti-Atlas Panafrican belt hosts numerous chromitite orebodies within the peridotite section of the oceanic mantle. The chromitites are strongly affected by serpentinization and metamorphism, although they still preserve igneous relicts amenable for petrogenetic interpretation. The major, minor and trace element composition of unaltered chromite cores reveal two compositional groups: intermediate-Cr (Cr# = 0.60 – 0.74) and high-Cr (Cr# = 0.79 – 0.84) and estimates of parental melt compositions suggest crystallization from pulses of fore-arc basalts (FAB) and boninitic melts, respectively, that infiltrated the oceanic supra-subduction zone (SSZ) mantle. A platinum group elements (PGE) mineralization dominated by Ir-Ru-Os is recognized in the chromitites, which has its mineralogical expression in abundant inclusions of Os-Ir alloys and coexisting magmatic laurite (RuS 2 ) and their products of metamorphic alteration. Unusual mineral phases in chromite, not previously reported in this ophiolite, include super-reduced and/or nominally ultra-high pressure minerals moissanite (SiC), native Cu and silicates (oriented clinopyroxene lamellae), but “exotic” zircon and diaspore have also been identified. We interpret that clinopyroxene lamellae have a magmatic origin, whereas super-reduced phases originated during serpentinization processes and diaspore is linked to late circulation of low-silica fluids related to rodingitization. Zircon grains, on the other hand, with apatite and serpentine inclusions, could either have formed after the interaction of chromitite with mantle-derived melts or could represent subducted detrital sediments later incorporated into the chromitites. We offer a comparison of the Bou Azzer chromitites with other Precambrian ophiolitic chromitites worldwide, which are rather scarce in the geological record. The studied chromitites are very similar to the Neoproterozoic chromitites reported in the Arabian-Nubian shield, which are also related to the Panafrican orogeny. Thus, we conclude that the Bou Azzer chromitites formed in a subduction-initiation geodynamic setting with two-stages of evolution, with formation of FAB-derived intermediate-Cr chromitites in the early stage and formation of boninite-derived high-Cr chromitites in the late stage.

Variation in mineral element composition of landrace taro (Colocasia esculenta) corms grown under dryland farming system in South Africa

Taro [Colocasia esculenta (L.) Schott] has the potential to address food and nutrition insecurity in sub-Saharan Africa. However, the nutrient content of taro is yet to be fully elucidated. The objective of this study was to evaluate mineral element content as a proxy for nutritional value of different taro genotypes. The study evaluated 14 taro accessions at Roodeplaat and Umbumbulu in South Africa based on their calcium (Ca), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), sodium (Na), phosphorous (P) and zinc (Zn) content. The accessions were planted in a randomized complete block design, replicated three times under field conditions. The mineral element content varied significantly (p < 0.05) among the genotypes. Genotypes Amad7-2, Umbu8 and Amad101 exhibited high Ca (≥432 mg kg−1), Fe (≥32 mg kg−1) and Mg (≥229 mg kg−1) across the locations. The first principal component (PC) accounted for 33.7% of the variation and was strongly associated with Zn (r = 0.94, p < 0.001) and P (r = 0.89, p < 0.001). The second PC explained 29.7% of the variation and was associated with Na (r = 0.83, p < 0.001), Mg (r = 0.76, p < 0.001) and K (r = 0.55, p < 0.05). Fe and Mn contributed below the 12.5% threshold to the PCs and were considered as less discriminatory among the accessions. The negative correlations among some of the mineral elements would be a challenge for selection and breeding of nutritious taro accessions. This information is essential to select superior local accessions based on their mineral element content for developing breeding populations and lines for improving nutrition quality among poor households in sub-Saharan Africa.