Sc Contents Research Articles

Archean Metaterrigenous Rocks of the Karelian Province: Geological Position, Geochemistry, Sediment Provenance

The geology and composition of Archean terrigenous sedimentary rocks of the Karelian province (Baltic Shield) are studied in order to establish their positions in the structures of greenstone belts and their role in the provenance composition. It is shown that metaterrigenous rocks from the greenstone belts of the youngest Central Karelian domain, together with intermediate-to-felsic volcanic rocks, compose the main part of the sections, occurring at their bases, and are about 2745 Ma in age. In the belts of the West Karelian domain, metaterrigenous rocks compose the upper parts of the sections, and their age is 2745–2750 Ma. Geological data on the position of metaterrigenous rocks in the belts of the oldest Vodlozero domain also suggest their Neoarchean age. On this basis, it is concluded that metaterrigenous rocks mark the beginning of the Neoarchean stage of crust formation in the Karelian province. According to geochemical data, metagreywackes are predominant among the Archean metaterrigenous rocks of all three domains. At the bases of the sections of some structures, polymictic conglomerates are present with the predominance of tonalite, trondhjemite, and, less often, granodiorite pebbles and with a subordinate amount of igneous rocks of different compositions. Low CaO and Na2O contents and CIA < 55 indicate an insignificant degree of weathering. The Th, Co, Sc, Hf, and La contents indicate a leading role of the TTG-association rocks in the compositions of the sources for all the studied structures. The influence of the basic source was small and affected exclusively Ti, Y, and heavy REE contents in metaterrigenous rocks. The role of komatiites as a source of detrital material was insignificant.

Fluid evolution of the Humedo porphyry-related gold deposit, southern Ecuador: Evidence from the boron isotope and chemical variations of tourmaline

Coexisting porphyry Cu-Au and low- to intermediate-sulfidation epithermal Au-Ag mineral systems are well developed in the Oligocene–Miocene volcanic and porphyry rocks in the Cangrejos–Zaruma district, Ecuador, northern Andes. The Humedo deposit, with a defined gold resource of 8 t @ 5 g/t, is a recently discovered Miocene porphyry–epithermal gold deposit in the southwest Cangrejos–Zaruma district. Here the textures, geochemistry, and B isotopes of tourmaline are investigated to understand the fluid evolution of the Humedo gold deposit. Four types of tourmaline (TurA–D) associated with three hydrothermal stages have been identified at Humedo: TurA in the matrix of stage II magmatic hydrothermal breccias, TurB in pervasive phyllic altered and silicified rocks of stage III, and TurC and TurD aggregates hosted in the extensively silicified rock and/or hydrothermal breccias of stage IV. All Humedo tourmaline belongs to the alkali group, with schorlitic–dravitic compositions. The TurA is characterized by the highest Fe, Nb, W, and Sn contents, the heaviest B isotopes (δ11B = 1.4–5.6 ‰), isovalent Al–Fe substitution, and low Eu/Eu* values, suggesting that oxidized magmatic fluids dominated during stage II. The TurB grains hosted by metamorphic and intrusive host rocks have different contents of Sc, Zn, V, and Ni, indicating a local impact on compositions from the host rocks. The low values of δ11B (−9.7 to −2.2 ‰), the correlation of δ11B with Co, and the Fe–Mg substitution of TurB suggest that fluids of stage III were reducing and possibly influenced by interaction with graphite-bearing meta ultramafic–mafic rocks of the Raspas Formation and/or Palenque Unit. The TurC–D is marked by the highest Mg contents of all groups, combined with the positive correlations of δ11B with Mg and Ba, suggesting the existence of external waters that interacted with shallow metasedimentary or volcanic sedimentary rocks during stage IV. The geochemistry and isotope characteristics of tourmaline thus record changes in the ore-forming fluid compositions (magmatic vs. external) and nature (oxidized vs. reduced) caused by fluid-rock interaction with regional country rocks in the Humedo porphyry–epithermal system.

Geochemistry of trace elements in rock-forming minerals of gneisses and granites of the Murzinka granite area, Central Urals

The Murzinka granite area (Central Urals), which combines Murzinka granite pluton and underlying rocks of the Murzinka-Adui metamorphic complex, exhibits an evident wetrending geochemical zonation of magmatism with increasing of Rb, Li, Nb and Ta contents and decreasing ba and Sr contents and K/Rb, zr/Hf and Nb/Ta ratios from vein granites of the Yuzhakovo complex to granites of the Vatikha complex and further to granites of the Murzinka complex (Fershtater et al., 2019). To develop the ideas about geochemical zonation of the Murzinka granite magmatism, as well as about the role of gneisses of the Murzinka-Adui metamorphic complex in the formation of granites, we studied the distribution of trace elements in biotite and feldspars of gneisses and granites. Biotite shows an increase in Li, Rb, Cs, Nb, Ga, zn, Mn, Sc, Sn and Tl contents and a decrease in V, Cr, Co, Ni, Y, zr and ba contents from vein biotites of the Yuzhakovo granites to two-mica granites of the Murzinka complex. The composition of feldspars also changes in this direction: plagioclase is enriched in Li, Rb, Cs, be, zn and depleted in Sr, ba, Ga and Pb and K-feldspar is enriched in Rb and depleted in Sr and ba. The varying trace element composition of rock-forming minerals of gneisses and granites is explained by We-trending change in the composition of a crustal protolith, as well as the formation conditions of granites. Figures 6. Tables 4. References 17.

Mineralogy and geochemistry of chloritholites from the Nepryakhino gold field, South Urals

The chlorite rocks (chloritolites) exposed in a bedrock of the Mokhovoe boloto (Moss swamp) gold placer (East Uralian Megazone, South Urals), which occurs on ultramafc rocks, are studied. The trace element composition of chloritolites is characterized by elevated contents of Mn, Ti, V (hundreds of ppm), Cu, zn, Ni, Co, Cr, zr, Li, Sc (tens of ppm), w, zr, Y and REE. Chloritolites contain up to 3 vol. % of disseminated magnetite, ilmenite and accessory minerals (rutile, xenotime, monazite, zircon, apatite, scheelite, U-bearing thorite) from a mineral assemblage, which cocrystallize with the main volume of chlorite. The mineralogical and geochemical features of the Mokhovoe boloto chloritolites and gold-bearing chloritolites of the Karabash massif in the Main Uralian Fault zone are slightly similar. The elevated Ti and P contents of the studied chloritolites, the level of REE contents corresponding to mafc rocks, and the lack of relict chromite indicate their possible metasomatic formation after dolerite dikes known within Chebarkul-Kazbai ultramafc complex. Figures 8. Tables 7. References 14.

Ash Characteristics and Selected Critical Elements (Ga, Sc, V) in Coal and Ash in Polish Deposits

The chemical composition of coal ash and the content of the critical elements Ga, Sc, and V in coal and ash are examined herein. In this study, lignite and bituminous coal from Polish deposits were used. The coals were subjected to ultimate and proximate analysis; the petrographic composition was determined based on maceral groups. The chemical composition of ash and the content of critical elements were determined using ICP-MS. The obtained results were correlated and Pearson’s linear correlation coefficient was determined. Based on the correlation analysis, the relationship between the chemical composition of ash and the proximate and ultimate analyses was demonstrated. The content of selected critical elements in the tested deposits was lower than the Clarke value in coal. However, in some deposits these contents are much higher in coal ashes. The higher levels of Ga, V, and Sc in the ash are associated with Al2O3. Therefore, it can be stated that ashes can be a potential source of some raw materials. The highest concentrations of critical elements in coal and ash were recorded in the Lublin Coal Basin. Supra-Clarke contents of Ga, V, and Sc were recorded in the Bogdanka coal mine.

Chlorite as an exploration indicator for concealed skarn mineralization: Perspective from the Tonglushan Cu–Au–Fe skarn deposit, Eastern China

Compositional variations of chlorite have been increasingly used to trace the magmatic–hydrothermal fluid evolution, as well as exploration vector toward concealed orebodies. This method has been widely applied to porphyry Cu (–Au) systems, but related research on skarn systems remain scarce. The Tonglushan Cu–Au–Fe deposit (86.3 Mt @ 1.66% Cu, 0.94 g/t Au and 39.4% Fe) is one of the largest Cu–Au polymetallic skarn deposits in the Middle–Lower Yangtze River metallogenic belt (MLYRB, Eastern China). Based on detailed petrographic observation, we present new EPMA and LA–ICP–MS elemental data for the Tonglushan chlorite, and discuss their implications on hydrothermal fluid evolution and exploration of concealed skarn orebodies there. At Tonglushan, chlorite alteration is well developed in the main Cu–Au sulfide ore stage. Three types of chlorite have been identified, i.e., disseminated chlorite replacing biotite and/or hornblende in the ore-causative quartz monzodiorite (porphyry), vein-type chlorite in quartz–chlorite–sulfides veins along/near the internal and external intrusive contact, and replacement-type chlorite that replaced garnet, diopside, epidote and Fe oxides in the skarn mineralization center.All the Tonglushan chlorite samples belong to trioctahedral chlorite and have similar crystallization temperatures (163–351 °C). The substitution mechanisms of Fe2+ ⇔ Mg2+, Tschermark (AlivAlvi ⇔ Si (Mg2+, Fe2+)) and di-trioctahedral (3(Mg2+, Fe2+) ⇔ □ + 2Alvi) are likely important for the Tonglushan chlorite formation. Replacement-type chlorite shows higher contents of FeOT, mobile elements (e.g., Ca, Na, B, Sr, Pb, Zn and Sn) and ore-forming elements (e.g., Cu and Co), whereas the disseminated chlorite has higher contents of Ti, Li, LILEs (e.g., K, Rb, Ba and Cs) and incompatible elements (e.g., V, Sc, Co and Ni). Meanwhile, the vein-type chlorite has similarly high contents of Ti, Li, V, Sc and Ni to the disseminated chlorite, but has higher FeOT and Cu contents but lower MgO content than the latter. Such compositional differences may have mainly attributed to the protolith (or precursor minerals) and hydrothermal fluid chemistry. Integrating the chlorite petrographic features and chemical compositions, we suggest that elevated FeOT and B contents and Fe/(Fe + Mg) ratios, and lower MgO, Al2O3, Ti, V and Sc contents can serve as proximal indicator for exploring concealed skarn orebodies at Tonglushan, as well as other similar Cu–Au–Fe skarn deposits in the MLYRB.

Structural and piezoelectric properties of ultra-thin ScxAl1−xN films grown on GaN by molecular beam epitaxy

ScxAl1−xN (x = 0.18–0.40) thin films of ∼28 nm thickness grown on metal polar GaN substrates by molecular beam epitaxy are found to exhibit smooth morphology with less than 0.5 nm roughness and predominantly single-phase wurtzite crystal structure throughout the composition range. Measurement of the piezoelectric d33 coefficient shows a 150% increase for lattice-matched Sc0.18Al0.82N relative to pure aluminum nitride, whereas higher Sc contents exhibit lower piezoelectric coefficients. The electromechanical response of the epitaxial films correlates with the crystal quality and the presence of zinc blende inclusions, as observed by high-resolution electron microscopy. It is further found that the polarity of the epitaxial ScxAl1−xN layers is locked to the underlying substrate. The measured electromechanical properties of epitaxial ScxAl1−xN, their relation to the atomic crystal structure and defects, and its crystal polarity provide useful guidance toward the applications of this material.

Element geochemical characteristics, provenance attributes, and paleosedimentary environment of the Paleogene strata in the Lenghu area, northwestern Qaidam Basin

The Lenghu area is a key exploration block in the northwestern Qaidam Basin. Due to the low exploration level, the provenance and paleosedimentary environment of the Paleogene strata is not clear. Based on the major and trace element contents and the carbon and oxygen isotopes of 547 samples collected from the Paleogene strata (E32, E31, and E1+2), this study investigated the provenance attributes and paleosedimentary environment of the entire Paleogene period. The samples from the Paleogene strata have relatively low contents of SiO2 (39.75%–61.81%) and Al2O3 (6.23%–20.48%) and high contents of La, Sc, and Co (223.07 ppm, 273.84 ppm, and 325.45, respectively). Moreover, the La–Th-Sc, Ti/Zr–La/Sc and SiO2–K2O/Na2O discrimination diagrams suggest that the tectonic environment of the provenance is an oceanic island arc. The Co/Th–La/Sc and Zr/TiO2-(V + Ni + Cr)/Al2O3 diagrams indicate that the provenance lithology of the study area is mafic rocks with a high degree of weathering. These results imply that the source rocks of the Paleogene strata are the mafic submarine volcanic rocks of the Tanjianshan group in the Saishiteng Mountains. The Sr/Cu, Sr/Rb, and Mg/Ca indexes indicate that the paleosedimentary environment had a humid climate with a trend of slight aridity. The Sr/Ba and Rb/K ratios and the isotope coefficient Z (calculated by carbon and oxygen isotopes) indicate that the paleosalinity of the water body was predominantly fresh water with a salty trend from the Early to the Late Paleogene. The paleoredox environment during the Paleogene sedimentation was relatively oxidized with a reduction trend based on the V/(V + Ni) and V/Cr values. This combined with the trend of increasing paleosalinity suggests that there was a relatively large lake transgression in the Late Paleogene.

Effect of Sc Content on the Microstructure and Properties of Al–Mg–Sc Alloys Deposited by Wire Arc Additive Manufacturing

Despite showing considerable potential, wire arc additive manufacturing (WAAM) has been limited to producing Al–Mg alloys. As the addition of Sc can improve the mechanical properties of Al–Mg alloys, in this study, Al–Mg–Sc alloy deposits with different Sc contents were prepared by a WAAM process. The porosity, microstructure, and mechanical properties of the deposits were studied. At Sc contents less than 0.15%, Sc was completely dissolved in the Al matrix without grain refinement, and the mechanical properties were slightly improved. At a Sc content of 0.3%, the primary Al3Sc phase precipitated out of the as-deposited body, resulting in an abrupt change in the microstructure, significant grain refinement, significantly increased tensile strength and yield strength, with a tensile strength, yield strength, and elongation of 372 MPa, 270 MPa, and 22.5%, respectively. Following heat treatment at 350 °C for 1 h, the grain boundaries were refined and the secondary Al3Sc phase was precipitated. Furthermore, the tensile strength and yield strength were significantly increased to 415 MPa and 279 MPa, respectively, and elongation decreased to 18.5%. At a Sc content of 0.45%, due to the aggregated precipitated phase, the coarsened grain boundaries and the limited solid solution amount of Sc in the α(Al) matrix (~ 0.25%), the mechanical properties were not further improved compared with the deposit with Sc content of 0.3%. Thus, based on economic considerations, the optimal Sc content was 0.3%. Owing to their enhanced mechanical properties, WAAM-produced Al–Mg–Sc alloys are expected to have a wide range of applications in aviation, aerospace.

The formation of magnetite ores of the Glubochenskoe deposit, Turgai iron belt, Russia: new structural, mineralogical, geochemical, and isotopic constraints

The magnetite ore bodies of the Paleozoic Glubochenskoe iron deposit (315.7 Mt at ~ 30.15% Fe) are located in the northern part of the Valerianovka arc zone (“Turgai belt”) within the Transuralian Megazone, Russia. They occur in calcareous-volcaniclastic rocks, exhibit layered textures, and contain primary seafloor hematite ores. The sequence of mineral formation reflects the diagenetic to metamorphic evolution of the iron ores: (i) finely dispersed hematite-1; (ii) tabular hematite-2 crystals; (iii) pseudomorphic magnetite-1 after hematite-2; (iv) zoned magnetite-2 crystals with relict hematite-2 (or magnetite-1); (v) thin oscillatory zoned magnetite-3 crystals; and (vi) magnetite-4 porphyroblasts. A gangue assemblage of Fe-rich and Fe–Mg chlorite, illite, quartz, albite, carbonates, rutile, and apatite with rare monazite, xenotime, and zircon occurs in ore and calcareous-volcaniclastic layers. The gangue clasts (volcanic glass, Ca–Mg and Ti minerals, and altered volcanic rocks) are replaced by hematite and further by magnetite. Low siderite δ13C values from layered magnetite ores (− 8.0 to − 19.5‰ PDB) indicate the presence of primary organic matter in calcareous-volcaniclastic rocks. Siderite δ18O values (6.5 to 17.4‰ SMOW) are evidence of isotopic exchange between minerals and fluids during metamorphism. Negative δ34S values for pyrite (down to − 4.5‰) likely indicate derivation of sulfur from organic matter in clastic sedimentary rocks. LA-ICP-MS analysis of zoned magnetite demonstrates highly variable Si, Al, Mg, Na, K, Ca, Ti, Mn, Rb, Y, Zr, Sr, U, and P contents, related to inclusions of gangue minerals. Elevated homogenous V and Ga contents and low contents of Sc, Co, Ni, Ge, As, Mo, Sn, and W (average < 5 ppm) indicate their incorporation into the structure of magnetite. All element contents (except V and Ga) are significantly higher in the inner zone of magnetite (magnetite-1) compared to the outer zone of magnetite (magnetite-2). The calcareous-volcaniclastic material, which was altered during submarine weathering and leaching, is proposed to be a major source of iron to form oxides. Altogether, the paragenetic sequence, and the mineralogical and geochemical data suggest the Glubochenskoe deposit can be characterized as a volcanic-sedimentary type of banded iron formation.

Helvine-group minerals from Norwegian granitic pegmatites and some other granitic rocks: Cases of significant Sc and Sn contents

ABSTRACTHelvine-group minerals from two granitic pegmatites have disparate compositions, from nearly pure helvine (Ågskardet, northern Norway; Devonian) to helvine close to ternary compositions (Heftetjern, southern Norway; Precambrian). Metagranite from Høgtuva (northern Norway; Precambrian with Caledonian metamorphic overprint) contains Zn-rich danalite. The Ågskardet helvine contains up to 0.46 wt.% SnO2, and the Heftetjern ternary helvine shows a maximum of 1.74 wt.% Sc2O3. Helvine minerals were also analyzed from three occurrences connected to peralkaline granite (ekerite) of the Permian Oslo Rift. Nearly pure genthelvite (99.19 mol.%) occurs in miarolitic cavities at Gjerdingselva. Two mineralogically different granitic pegmatites derived from the same ekerite pluton in the southern part of the Oslo Rift show quite distinct helvine compositions, from nearly continuous solid solution between helvine and genthelvite in crystals with oscillatory zonation (Rundemyr) to solid solutions midway between danalite and genthelvite (Bakstevalåsen). The Rundemyr crystals have a maximum SnO2 content of 1.28 wt.%. The incorporation of minor elements (Ca, Mg, Al, Sn, Sc) in helvine-group minerals is discussed with emphasis on their chalcophilicity characteristics. For stereochemical reasons, Sn in helvine minerals must be tetravalent, even if Sn2+ is more chalcophile than Sn4+.

Microstructural evolution upon heat treatments and its effect on corrosion in Al-Zn-Mg alloys containing Sc and Zr

Different contents of Sc and Zr were alloyed into Al-Zn-Mg alloys: Alloy A (0 pct Sc + 0 pct Zr), Alloy B (0.19 pct Sc + 0.09 pct Zr), and Alloy C (0.19 pct Sc + 0.18 pct Zr). The combined alloying of Sc and Zr promoted the primary phase of Al-Zn-Mg alloys to dissolve into the matrix during cold rolling, and produced Al3(Sc,Zr) precipitates by subsequent aging. The combined alloying of Sc and Zr restrained the recrystallization of Al-Zn-Mg alloys, and caused finer and more uniform grains by the two-stage solution. The distribution of texture was important to understand the microstructural evolution of alloys. The combined alloying of Sc and Zr with the two-stage solution promoted the increase of the cubic texture {001} <100>. The microstructural evolutions including the Al3(Sc,Zr) precipitates, the precipitation free zone (PFZ) width, the textures and the recrystallizations were the main factors affecting the corrosion resistance of the Al-Zn-Mg alloys containing Sc and Zr. Alloy C after the two-stage solution treatment followed by the two-stage aging had the best stress corrosion cracking (SCC) resistance and the highest electrochemical corrosion resistant properties.

Genesis of the oxidized Sn ores in the Gejiu district, Yunnan Province, SW China

The Gejiu Sn ore district, one of the largest Sn producing area (300Mt @1 wt% Sn) in the world, is located in the western margin of the Cathaysia Block, SW China. There are five types of Sn ores in the Gejiu district, including greisen, skarn, veined tourmaline, massive sulfide and oxidized. Among these types of Sn ores, the genesis of the oxidized Sn ores is most controversial, such as magmatic hydrothermal origin and sedimentary exhalative (SEDEX) or hot water deposition (Red Sea type). This paper reports U-Pb ages, fluid inclusions, trace elements and H-O isotopes of cassiterite from the oxidized Sn ores, aiming to solve this issue. LA-MC-ICPMS cassiterite U-Pb dating yielded an age of 86.7 ± 2.8 Ma, which is accordant with the formation ages (~86 Ma) of granitic intrusions in the Gejiu district. Two types of fluid inclusions in cassiterite from the oxidized Sn ores were observed, one type is CO2-rich inclusions (Type 1) and the other type is aqueous inclusions (Type 2). The homogenization temperatures range from 220 to 366 °C and the salinities range from 10.9 to 21 wt% NaCl equiv. for the two types of fluid inclusions. Furthermore, fluid inclusions in cassiterite from the oxidized Sn ores located at 300 m far away from granitic intrusions have higher temperatures (357–366 °C) than those located at 500 m (273–330 °C). Hence, the ore-forming temperatures tend to decrease with the distance far away from the magmatic hydrothermal center. The vapor components for the two types of fluid inclusions are CO2 and H2O, respectively, and the liquid phase compositions of them are all H2O. The CO2 in the ore-forming fluids may source from marble by decarbonization. This indicates that the precipitation of cassiterite is resulted from fluid immiscible. The δ18O values of fluid inclusions in cassiterite range from +6.1 to +7.7‰, and the δD values range from −135 to −153‰, indicating a mixture of magmatic and meteoric waters. Trace elements show that cassiterite is rich in In, Rb and U, but Ba, Nb and Ti are depleted. In addition, the lower Sr (0.4–2.1 ppm) and higher Sc (35.9–53.7 ppm) contents reflect that the formation of cassiterite is related to F-rich intermediate-acid magma. Cassiterite has a relatively low total REE contents (2.7–9.2 ppm) with negative Eu (δEu = 0.14–0.76) and Ce (δCe = 0.1–0.6) anomalies, indicating that the ore-forming environment is oxidized. This is consistent with the cassiterite precipitation conditions. Hence, all the evidence supports that the oxidized Sn ores are genetically associated with the Gejiu granitic magmatism.

Petrogenesis of Secondary Diatexites and the Melt Budget for Crustal Reworking

Abstract This study investigates the petrogenesis of diatexite migmatites and leucogranites in a granulite facies terrain and quantifies the melt budget for it. The anatectic rock types in the Ashuanipi Subprovince are: (1) melt-depleted orthopyroxene metatexite migmatite, (2) secondary diatexite migmatite formed where anatectic melt intruded, entrained and accumulated in the metatexite, and (3) leucogranite. The FeO, MgO, TiO2, Cr, Co and Sc contents of the diatexites are controlled by the fraction of entrained metatextite. However, most diatexites and many leucogranites are richer in (Na2O+CaO) but depleted in K2O relative to an anatectic melt + metatexite mixture. This, and the predominance of plagioclase + orthopyroxene frameworks in the diatexites, indicates loss of fractionated melt. Mass-balance models using the metatexite and compositions of fractionated melts and crystallised solids obtained from simulated crystallisation of the anatectic melt indicate that ‘typical’ diatexite formed by mixing ∼40% metatexite with ∼60% anatectic melt, and then when 8 to 30% crystallised, most (&amp;gt;73%) of the remaining melt was expelled, likely by shear-enhanced compaction. The processes making the diatexites and leucogranites expelled ∼50% of the initial amount of melt; some formed the K2O-rich leucodiatexites and leucogranites in the terrain, but most escaped. A melt budget for the present Ashuanipi surface made by combining mass-balance calculations and the area of each rock type reveals that it once held 3.05 times more melt than was generated there. The adjacent Opinaca Subprovince contains 10 times more leucogranite than partial melting there produced; moreover, its leucogranites are compositionally similar to fractionated melts expelled from the Ashuanipi. Combining these crustal levels and assuming a gradient of 30oC km-1, then ∼400 000 km3 of melt representing &amp;gt;68% of the total generated during crustal reworking in the Ashuanipi remained in the middle crust where temperatures were above the solidus.

Discrete Jurassic and Cretaceous Mineralization Events at the Xiangdong W(-Sn) Deposit, Nanling Range, South China

Abstract The Xiangdong W(-Sn) deposit is hosted in the Dengfuxian multiphase granites (biotite, two-mica, and muscovite granites) within the Nanling Range metallogenic belt in south China. Previous studies suggested that the W(-Sn) mineralization in the Xiangdong deposit is related to the Late Jurassic two-mica granite, whereas recently W-Sn–bearing quartz veins have also been identified in muscovite granite. We present new cassiterite and zircon U-Pb ages to constrain the timing of W-Sn mineralization and related granitic magmatism. Our laser ablation-inductively coupled plasma-mass spectrometry U-Pb dating of zircon grains, combined with previous zircon ages, in addition to the trace element composition of the muscovite granite, suggest the muscovite granite in the Dengfuxian pluton was emplaced at 145 to 142 Ma and shows highly evolved features. Cassiterite grains from the ore-bearing veins in two-mica granite yielded U-Pb ages of 151.6 ± 3.7 and 141 to 138 Ma, whereas cassiterite grains from quartz veins occurring in muscovite granite yielded a U-Pb age of 136.8 ± 3.3 Ma. The new ages and detailed geologic evidence indicate that the Early Cretaceous muscovite granite is also genetically related to W-Sn mineralization. Combining this with previously published data from the Late Jurassic two-mica granites and related mineralization, we suggest that there were two stages of W-Sn mineralization at Xiangdong. Arsenopyrite geothermometry from the two stages suggests temperatures of 300° to 491° and 308° to 450°C in stage I and stage II, respectively. Wolframite grains from the two stages also show different characteristics and patterns for their major and trace elements. The enrichment in Sc in wolframite suggests low-pH and low-Eh conditions for a fluid containing F– and/or PO43− complexes during stage I, whereas higher contents of Nb and Ta and lower contents of Sc in wolframite from stage II indicate relatively lower pH and higher Eh conditions. In combination with data from other recent studies, we propose that the 145 to 130 Ma interval represents a newly recognized W-Sn metallogenic period linked with highly evolved granites in the Nanling Range metallogenic belt. The Early Cretaceous muscovite granite is an important new target for W and Sn resources in south China.

Oxygen Incorporation in the Molecular Beam Epitaxy Growth of ScxGa1−xN and ScxAl1−xN

Secondary‐ion mass spectrometry (SIMS) is used to determine impurity concentrations of carbon and oxygen in two scandium‐containing nitride semiconductor multilayer heterostructures: ScxGa1−xN/GaN and ScxAl1−xN/AlN grown by molecular beam epitaxy (MBE). In the ScxGa1−xN/GaN heterostructure grown in metal‐rich conditions on GaN–SiC template substrates with Sc contents up to 28 at%, the oxygen concentration is found to be below 1 × 1019 cm−3, with an increase directly correlated with the scandium content. In the ScxAl1−xN–AlN heterostructure grown in nitrogen‐rich conditions on AlN–Al2O3 template substrates with Sc contents up to 26 at%, the oxygen concentration is found to be between 1019 and 1021 cm−3, again directly correlated with the Sc content. The increase in oxygen and carbon takes place during the deposition of scandium‐alloyed layers.

Determination of Scandium in mafic and ultramafic rocks of ophiolites from Luk Ulo Complex, Karangsambung, Central Java, Indonesia

Scandium (Sc) is important element for its utilization in modern industry. Initial Sc content in the parent rocks primary importance controlling the Sc concentrations in its weathered derivatives. This contribution examines the Sc concentrations in parent rocks of mafic and ultramafic rocks related to the ophiolite series in Luk Ulo Complex, Karangsambung, Central Java, Indonesia. The ophiolite series in this area are basalt, microgabbronorite, gabbronorite, websterite, and serpentinite from 5 locations of Medana, Lokidang, Parakansubah, Selogiri, and Pucangan areas. The general trend from the distribution of Sc in the ophiolite sequence of Medana and Parakansubah-Lokidang Rivers suggests the Sc contents increase from shallow to deeper levels of the sequence. The lowest concentrations of Sc in the ophiolite sequence of Medana and Parakansubah-Lokidang Rivers are in basalt, which are 24–29 ppm. In the middle sequence, the Sc concentrations are 27–34 ppm and 24–43 ppm, respectively in microgabbronorite and gabbronorite. The highest Sc concentrations are in websterite, which are 51–54 ppm, as the deepest sequence of the ophiolite in this area. Meanwhile, Sc contents in serpentinite from Selogiri and Pucangan areas are 5–11 ppm, which are considered the lowest Sc contents. It suggests that the pre-serpentinization mineral composition rather than the process of serpentinization determine the elemental abundance of Sc in serpentinite. The results are used to be an analog for Sc identification in the ophiolite belts in central Indonesia. This also considering that Luk Ulo Complex been established as National Geopark of Karangsambung-Karangbolong, so that mining activities are prohibited in this area.

Petrography and Geochemical Characterization of Dolerites from Figuil (Northern Cameroon) and L&amp;#233;r&amp;#233; (Southwestern Chad)

This work presents the petrographic and geochemical data of the dolerite dykes crosscutting the Pan-African basement of Figuil (North-Cameroon) and Lere (South-West Chad) in order to approach their petrogenesis and their emplacement context. Two groups of dolerites have been highlighted by petrographic and geochemical studies. These groups were discriminated by their TiO2, Fe2O3, REE, Ba, Nb, Zr, La and Hf contents which are relatively higher in group I; group II, on the other hand, has higher MgO, Mg#, Sc, Ni and Cr contents. The mineralogical assemblage of these dolerites is made up by plagioclases, pyroxenes, olivine, oxides, amphibole, biotite and sometimes pyrite, calcite, apatite, epidote and chlorite. The behaviour of the major and trace elements suggest that studied dolerites have an evolution dominated by fractional crystallization. Most dolerite samples show higher REE concentrations and (La/Yb)N > 8.7, (Tb/Yb)N > 1.9 and Dy/Yb > 2 ratios characterizing a garnet-bearing mantle. The difference in incompatible elements between the two groups is explained by the degree of partial melting of the same source which becomes more important over time. Low (Ce/Yb)N values (3.3 - 11.58) also suggest relatively low partial melting degree of the source. Fractional crystallization process was possibly combined with minor crustal contamination as shown by enrichment of Th/Yb from group II to Group I that might be due to turbulent magma emplacement. The chemical compositions of these dolerites are similar to that of continental tholeiites with slightly moderate negative Nb-Ta anomalies which are attributed to crustal contamination of magmas. As other dolerites of Cameroon, continental tholeiitic signature of the studied dolerites is evidenced in geotectonic discrimination diagrams with Group II dolerite compositions falling within the field of tholeiitic basalts and group I within the field of alkali basalts.

Genesis of karst bauxite-bearing sequences in Baofeng, Henan (China), and the distribution of critical metals

Bauxite-bearing sequences are not only the main economic sources of Aluminum, but also of many critical metals. The distribution of critical metals was determined from six bauxite profiles in Baofeng, and an evolution model was proposed for the formation of bauxite-bearing sequences. Following a terrestrial deposition of the lower pisolitic bauxite horizon and the underlying clayey layer, transportation and redeposition of bauxitic materials during submergence led to the formation of the upper bauxite horizon presenting finely-clastic and oolitic textures, as well as the intercalated clayey layers. Both bauxite ores and clay samples contain highly elevated contents of Li, B, Sc, V, Ga, Zr, Nb, W and total REEs. Li contents are extremely low in high-grade bauxite ores (10.92–44.77 ppm), compared to highly elevated values in low-grade bauxite ores (35.81–1601 ppm) and clay samples (38.54–1965 ppm), enlightening a new potential resource for Li, the bauxite-bearing sequences resting on karstified carbonate. The distribution pattern of Ga is similar to that of Li, and the correlation analysis indicates that Ga is primarily associated with silicates, i.e. clay minerals. The vertical distribution of Li, B, V, Cr and Ga shares the same pattern, similar to that of K2O and SiO2, being highly enriched in clayey layers relative to bauxite horizons. Both Sc and total REEs are also highly enriched in Baofeng bauxite profiles, highlighting a potential Sc and REEs resource.

Effect of Al and Sc on deformation behavior of FeCoNi multi-element alloys

Abstract The effects of Al and Sc on mechanical properties of FeCoNi multi-element alloys (MEAs) were investigated by compressive tests. The microstructures of FeCoNi MEAs with different contents of Al and Sc were characterized and the strengthening mechanisms were discussed. The results show that FeCoNi MEA with a low content of Al has a face-centered cubic (FCC) structure. The yield strength increases linearly with the increase of Al content, which is largely caused by solid solution hardening. Further addition of Sc can promote the formation of a new phase in (FeCoNi)1−xAlx MEAs. A minor addition of Sc can significantly increase the yield strengths of (FeCoNi)1−xAlx MEAs with a low Al content and improve the compressive plasticity of (FeCoNi)1−xAlx MEAs with a high Al content.