High SiO2 Contents Research Articles

Physico-Chemical, Mineralogical Properties and Valorization of Bentonite Material from Iboughardain Area (North-Eastern Rif, Morocco): Application in Dyes Removal

This paper focuses on the characterization and valorization of Moroccan bentonite in dye removal. The stratiform Iboughardain deposit is located in Kert basin (Northeast Rif, Morocco), It is accessible via a tarred road connecting Nador-Seghanghan-Dar Kabdani at a distance of approximately 30 km from Nador. Its Lambert coordinates are X = 709.300, Y = 501.000 (topographic sheet Kebdani to 1/100.000). Bentonite outcrops occur as alterations of the lower horizontal layers of trachyandesite tuff and cinerite. This alteration is in contact with greenish Miocene marl. The mineralogy composition of the samples examined indicates the presence of various contents of montmorillonite and associated minerals such as feldspars and quartz. The mineralogy dominated by aluminosilicates is reflected in the chemical composition which shows high contents of SiO2 and Al2O3. The other oxides have moderate proportions. It is Fe2O3 (1.90 wt%), K2O (0.90 wt%), MgO (5.65 wt%), and MnO (0.07 wt%). Geotechnical results show that the sample is very plastic. Importantly, the experimental adsorption results clearly demonstrate that the clay from the Iboughardain region effectively clarifies the dyeing. The removal of methyl orange (CMO = 140 mg/l) was shown to be significant (98%) under activated bentonite compared to doped bentonite (B-TiO2 20%wt). In addition, the removal of methylene blue staining at a high concentration (CMB = 120 mg/l) was able to reach significant removals of 80 and 99.9% using raw and doped bentonite, respectively.

Petrogenesis of the Laoshan Suite in the Jiaodong Peninsula (Eastern China): An Oxidized Low Ba–Sr A1-Type Granite

The Jiaodong Peninsula is closely related to Mesozoic granites in terms of spatial and temporal aspects. However, the specific association between the genesis of gold mineralization and these granites remains unclear. It is also ambiguous why Laoshan-type granites, which are similar to Mesozoic granites, are not gold mineralized. In this study, we analyzed the Laoshan granites and compiled Mesozoic magmatic rock data (Linglong, Guojialing, and Weideshan suites) of the Jiaodong Peninsula. We performed whole-rock major and trace elements, LA–ICP–MS zircon U–Pb geochronology and geochemistry analyses. Our zircon U–Pb data denote that the Laoshan granite was emplaced during the 118 ± 1 Ma. The Laoshan granite is characterized by high SiO2 content (76.03–80.28 wt.%), high TFe2O3/MgO (11.1–27.1) and Ga/Al (3.0–3.5) ratios, high zircon saturation temperature (809–850 °C), and negative Eu (Eu/Eu* = 0.05–0.08) anomalies, showing A-type granite characteristics. Furthermore, the Laoshan granite is identified as an A1-type granite with low Ba (33.1–42.0 ppm) and Sr (14.1–21.0 ppm) contents. It was formed in an extensional tectonic environment induced by the subducting slab roll-back of the Paleo-Pacific Plate, mainly from the partial melting of lower crustal materials, mixed with a small amount of mantle components. Zircon trace elements indicate that the Laoshan suite had relatively high oxygen fugacity and temperature (ΔFMQ = + 2.43 to + 4.22, T-Ti in zircon (mean) = 796 °C) compared to the pre-mineralization and contemporaneous mineralization magma. We propose that oxidized adakitic magma (Weideshan suite) may contribute to the enrichment and mineralization of gold. Although Laoshan-type granite also has a high oxygen fugacity, its location is distant from the ore-controlling faults, which ultimately hinders the formation of gold mineralization. From the Jurassic to the Cretaceous, the tectonic and geochemical properties of magmatic rocks in the Jiaodong Peninsula have changed, and gold deposits are formed in such a transitional process (compression to extension, reduction to oxidation).

Hydrothermally Synthesized Hydroxyapatite-Silica Composites with Enhanced Mechanical Properties for Bone Graft Applications

The demand for synthetic bone grafts has increased in recent years. Hydroxyapatite (HA) is one of the highly suitable candidates as a bone graft material due to its excellent biocompatibility and high osteoconductive properties with low toxicity. HA has disadvantageous mechanical strength showing relatively fragile and brittle behavior due to its high hygroscopic properties. This leads to improper mechanical properties for such grafting applications. Therefore, HA should be combined with another material with similar biocompatibility and high hardness, such as SiO2. In this work, HA/SiO2 (HAS) composite material was prepared via a hydrothermal method to obtain the high purities of HA with a particle size of approximately 35 nm and around 50% crystallinity. It was found that the addition of SiO2 stimulated the composite system by forming an orthosilicic acid complex that can reduce the overall solution’s pH, thus contributing to the integrity and stability of the HAS composite. Therefore, higher SiO2 contents in the HAS composite can enhance its mechanical stability when immersed in simulated body fluid (SBF). Our work demonstrated that HAS can highly improve HA material’s hardness and mechanical stability under immersion of SBF. The Vickers test showed that the 0.05 GPa hardness in 10% SiO2 increased to 0.35 GPa hardness with the addition of 20% SiO2. The crystal structures of HAS were analyzed using X-ray diffraction, and the morphology of the HAS composites was observed under electron microscopy.

Combined operando and ex-situ monitoring of the Zn/electrolyte interface in Zn-ion battery systems

Operando optical microscopy enables imaging at the interface between the Zn electrode and the electrolyte of 1 M ZnSO4(aq) in the symmetrical Zn/Zn cells assembled as the pouch cells with the mechanical load of 0.8 MPa. The imaging was executed during cycling of Zn plating and stripping at the different current densities of 0.5, 1.0, 2.0, and 4.0 mA cm−2, and the areal capacity of 2 mAh·cm−2. When the current densities are below 4.0 mA cm−2, no intense Zn dendrites are observed. However, at 4.0 mA cm−2, the severe Zn dendrites can penetrate through the separator and cause short-circuiting. From the electrochemical perspective, the voltage profile of such system drops to almost zero volt. Both operando optical and ex-situ synchrotron X-ray imaging further prove the appearance of the Zn dendrites. By Raman spectroscopy and X-ray diffraction, the cycled Zn electrode surface contains passivation species of Zn4(OH)6SO4, ZnO, and Zn(OH)2 that could limit the active surface area for the Zn plating/stripping, accelerating the localized current density and favoring the growth of Zn dendrites. With the SiO2 additive of 0.5% w/v in 1 M ZnSO4(aq), the severe Zn dendrites disappear, as well as the cycled Zn/electrolyte interface becomes close to the pristine state; low degree of the Zn electrode roughness and the Zn surface passivation is noticed. The appearance of the claimed Zn surface morphology was also confirmed by Scanning Electron Microscopy (SEM). In turn, too low or too high SiO2 content in the electrolyte does not generate desirable effects. A high level of Zn dendrites and short circuiting are still recognized. Hence, both the operando and ex-situ characterizations can mutually validate the phenomena at the Zn/electrolyte interface.

Petrogenesis of early Cretaceous granites in Mufushan complex, northeastern Hunan Province: Insights on middle-late Mesozoic tectonic evolution of eastern South China

We present new field observations, whole-rock major and trace elements, Sr-Nd-Pb-Hf isotopes and zircon UPb ages for the Mesozoic granites in the Mufushan complex, eastern South China. The age determinations by LA-ICP-MS UPb dating of zircons indicate that the porphyritic biotite granites and two-mica monzogranites have ages of ∼136 Ma and ∼ 130 Ma, respectively. These granites display highly evolved S-type granite geochemical characteristics, with high SiO2 (70–74 wt%) contents, high 10000*Ga/Al ratios (2.3–3.2, average of 2.8) and weakly peraluminous (A/CNK > 1.1). Both types of granites are enriched in large ion lithophile elements (LILEs, e.g., Rb, K, Ba, Sr) and depleted in high field strength elements (HFSEs, e.g., Nb, Ta, Ti), with negative anomalies of Eu and positive anomalies of Pb, which are akin to continental arc rocks. The two-mica monzogranites have high 87Sr/86Sr(i) (0.71355–0.71535), 206Pb/204Pb(i) (18.105–18.157), low εNd(t) (−9.1 to −9.6) and εHf(t) (−4.1 to −10.4), similar to those of the porphyritic biotite granites which are characterized by high 87Sr/86Sr(i) (0.717337–0.71692), 206Pb/204Pb(i) (18.134–18.580), low εNd(t) (−9.1 to −9.7) and zircon εHf(t) (−6.8 to −3.3). The similar emplacement ages and mineral assemblages as well as Sr-Nd-Hf isotopic signatures indicate their derivations were likely derived from a common magma source. These early Cretaceous granites yield two-stage Nd model ages of 1.6–1.7 Ga, similar to the two-stage Hf model ages of 1.3–1.8 Ga. The presence of Neoproterozoic and subordinate Mesoproterozoic zircons within the granitic rocks suggest a significant contribution of ancient crustal materials involved in the genesis of the magmas. In combination with comprehensive studies on the magmatic rocks, the early Cretaceous Mufushan granitic rocks may have experienced an extensive enrichment process, contemporaneously with partial melting of the Neoproterozoic volcanic-sedimentary sequences that produced the arc-like rocks. Almost simultaneously, an extensional event caused by the subduction and slab roll-back of the Paleo-Pacific plate (Izanagi plate) dominates the middle-late Mesozoic tectonics in eastern South China. This extensional regime was accompanied by the underplating of mantle-derived magma and crustal melting, producing the widespread early Cretaceous granites in adjacent regions. The development of coeval basin-and-range structures with the production of contemporaneous magmatic rocks and related polymetallic deposits in eastern South China are all related to slab roll-back tectonics.

Continental crustal growth and differentiation in intraoceanic arcs: Insights from plagiogranites in the forearc ophiolite of the southeastern Central Asian Orogenic Belt, China

Oceanic plagiogranites in subduction initiation zones record key information of continental crustal growth and differentiation. However, their petrogenesis remains controversial, due to the lack of complete subduction initiation records in most of ophiolites. In this study, we report a newly recognized plagiogranite suite (including intrusive plagiogranite porphyries and extrusive rhyolites) from the Diyanmiao forearc ophiolite in Inner Mongolia, southeastern section of the Centra Asian Orogenic Belt, where a relatively complete forearc magmatic succession is preserved. In the Diyanmiao suite, the plagiogranite porphyries, occur as small irregular dykes or pods intruding pillowed transitional lavas, and rhyolite lavas within or overlying the upper boninitic lavas, from bottom to top. Zircon UPb dating of two plagiogranite porphyry samples and one rhyolite sample yields mean ages of 322.5 ± 3.6, 319.9 ± 1.9, and 319.6 ± 2.6 Ma respectively. Similar to other oceanic plagiogranites, the plagiogranite porphyries and rhyolites in our study exhibit high SiO2 and Na2O contents and low K2O. They have chondrite-normalized flat to slightly depleted rare earth element patterns, and significantly negative Nb, Ta, and Ti anomalies similar to arc magmatic rocks. They also display high positive εHf(t) values (+12.5 − +18.7) and εNd(t) values (+6.9 − +10.0), comparable to the values of their host rocks. Petrographic characteristics and Rhyolite-MELTS modeling suggest that the plagiogranite porphyries and rhyolites were generated by high degree of crystal fractionation from parent tholeiitic basalt magmas. Our results suggest that melt migration triggered by fractional crystallization of mafic magmas played a vital role in the growth of continental crust in intraoceanic arcs in the southeastern Paleo-Asian Ocean.

Poly‐SiOx Passivating Contacts with Plasma‐Assisted N2O Oxidation of Silicon (PANO‐SiOx)

Passivating contacts are crucial for realizing high‐performance crystalline silicon solar cells. Herein, contact formation by plasma‐enhanced chemical vapor deposition (PECVD) followed by an annealing step is focused on. Poly‐SiOx passivating contacts by combining plasma‐assisted N2O‐based oxidation of silicon (PANO‐SiOx) with a thin film of phosphorus (n+) or boron (p+)‐doped hydrogenated amorphous silicon oxide (a‐SiOx:H) are manufactured. Postannealing is conducted for transitioning a‐SiOx:H into poly‐SiOx. The aim is to achieve a contact with low absorption and high‐quality passivation. It is demonstrated that by tuning the plasma oxidation process time and power, the PANO‐SiOx thickness and its passivation quality can be controlled. A higher SiO2 content is observed in PANO‐SiOx than in the nitric acid oxidation of silicon (NAOS‐SiOx) counterpart. PANO‐SiOx acts as a stronger diffusion barrier for both boron and phosphorus atoms compared to NAOS‐SiOx, affecting the dopant distribution during annealing. Implied open‐circuit voltages up to 751 and 710 mV for n+ and p+ flat symmetric samples, respectively, are demonstrated. With respect to standard thermally grown SiO2 tunneling oxide combined with (in/ex )situ‐doped low‐pressure chemical vapor deposition poly‐Si, this study presents a simple alternative for manufacturing passivating contact fully based on PECVD processes.

Geochronology and Geological Implications of Paleoproterozoic Post-Collisional Monzogranitic Dykes in the Ne Jiao-Liao-Ji Belt, North China Craton

Hardly any previous studies have focused on the granitic dykes which intrude into the Paleoproterozoic Liaohe Group in the Liaodong Peninsula, northeast of the North China Craton. In situ zircon U-Pb dating, Lu-Hf isotopic and geochemical analyses on three representative monzogranite dykes were taken in this study. These dykes have relatively high content of SiO2 (72.20%–74.78%) and K2O (2.83%–6.37%), and have characteristics of high-K calc-alkaline to shoshonite series. Two dyke samples have I-type granite features and have high Sr/Y ratios and positive Eu anomalies, showing an adakitic feature. Another dyke has a high ratio of Ga/Al, but has a low Zr saturation temperature, which differs from the typical A-type granite. Zircon grains from these three dykes have typical magmatic zoning in CL images and yield consistent U-Pb ages of ~1859–1852 Ma, which are interpreted as the crystallization ages of these dykes. Hf isotopic analyses yield mainly negative εHf(t) values and TDM2 ages of 2782–2430 Ma, similar to those of the 2.2–2.1 Ga granitoids and meta-sedimentary rocks (the Liaohe Group), indicating these monzogranitic dykes may have been sourced from melting of Paleoproterozoic granitoids and meta-sedimentary rocks. The monzogranitic dykes were generated under a post-collisional geological setting after the Jiao-Liao-Ji orogeny process.

Influence of SiO2‐Adding on the Thermophysical Properties and Crystallization Behavior of Ladle Slags

The thermophysical properties (viscosity, density, and surface tension) of the secondary metallurgical slags with various CaO/Al2O3 ratios (0.56–1.99) and SiO2 (1–20 wt%) contents are investigated. The results show that the addition of SiO2 increases the viscosity of the cleanness and desulfurization slags (CaO/Al2O3 ratios ≥1). In slag with a higher Al2O3 content (CaO/Al2O3 < 1) and constant CaO content, the viscosity shows a first decreased and then increased phenomenon with the addition of SiO2. Moreover, the breakpoints of the viscosity are strongly lowered with the addition of SiO2. Both the density and surface tension of slags show a decreasing tendency with the SiO2 addition. Moreover, the single hot thermocouple technique method is applied to investigate the crystallization process of the slags, and the result shows that with high SiO2 contents, glassy layers are formed on the molten slags.

Geochronology, geochemistry, and Sr–Nd isotopes of Permian dike swarms in the Beishan orogenic belt, southernmost Central Asian Orogenic Belt: Petrogenesis and implications for geodynamic setting

ABSTRACT Permian mafic dikes crop out widely within Beishan area in the southernmost Central Asian Orogenic Belt (CAOB). These mantle-derived products provide important clues for elucidating the genesis and geodynamic setting of Permian magmatism. The mafic dikes within the Beishan area display zircons U–Pb ages of 281 ± 4 Ma. Characterized by low SiO2 (44.88–47.73 wt.%) and high Mg# values (62.2–68.6), the type 1 dikes are relatively depleted in light rare earth elements (LREEs; (La/Yb)n = 0.72–1.43) but enriched in large ion lithophile elements (LILEs). They show high positive εNd(t) values (6.6–8.5) with a range of (87Sr/86Sr) i (0.703477–0.705789) ratios. In contrast, the type 2 dikes have higher SiO2 content (47.47–51.13 wt.%) and lower Mg# (40.9–63.0). They are enriched in LREEs ((La/Yb)n = 1.79–5.02) and LILEs, and have lower εNd(t) values (3.8–7.4) with a variable range of (87Sr/86Sr) i (0.702873–0.706949) ratios. Thus, the type 1 dikes resulted from lower degrees of fractional crystallization and contamination than the type 2 dikes. Considering the LILEs and Pb enrichments, high field strength elements depletions, and high Ba/Th (86–460) ratios, the mantle source was metasomatized by subduction-related fluids. These dikes should be derived from high degrees (>20%) of partial melting of a Sr–Nd isotope-depleted, phlogopite-bearing spinel lherzolite lithospheric mantle according to their high Rb/Sr (0.04–0.24), low Ba/Rb (0.9–3.3), low La/Sm, and constant Sm/Yb ratios in addition to Sr–Nd depletion. Combined with the coeval evidence of regional geology and novel tectonic discriminate diagrams, we suggest that the mafic dikes in Beishan area formed in arc-related setting rather than intracontinental setting during the Permian. The metasomatized lithospheric mantle by subduction-related fluids were heated by upwelling asthenosphere mantle triggered by the slab roll-back, resulting in the formation of the parental magma of the mafic dikes.

Waste to concrete material: Potential Study of Chemical Characterization of Coal Fly Ash and Bottom Ash

This research focuses on the chemical properties of coal fly ash (CFA) and coal bottom ash (CBA) obtained from Sultan Azlan Shah Power Plant and compares them with the characteristics of ordinary Portland cement (OPC). Coal has been recognised as a significant fuel source in Malaysia, where it is extensively employed in the creation of steel, cement, and power. When coal is burned to create power, several different types of coal ash are created, including fly ash, bottom ash, boiler slag, and clinker. Fly and bottom ash, however, are the main coal ash waste products that have been created. In an effort to create sustainable concrete from waste, a number of studies have been carried out to ascertain the chemical characteristics of fly and bottom ash. These tests include Energy Disperse X-Ray (EDX), Mineralogy (XRD), and X-Ray Fluorescence (XRF). From the SEM result, fly ash has smaller particles and a spherical, uniform shape than bottom ash and cement. Fly and bottom ash from the Sultan Azlan Shah power plant contain a number of elements, including Silicon (Si), Aluminium (Al), Oxygen (O), Calcium (Ca), Titanium (Ti), Iron (Fe), Magnesium (Mg), Potassium (K), Carbon (C), and Sodium, according to Energy Dispersive X-Ray (EDX) test. The fly ash is primarily an amorphous material, with the presence of quartz crystalline phase (SiO2) at 24.3% and bottom ash at 31.1%, according to X-ray Diffraction (XRD) data. For the mullite phase (3AlO3.2SiO2), fly and bottom ash show results of 24.9% and 14.5%, respectively. According to an X-ray fluorescence (XRF) investigation, the main constituents of fly and bottom ash are silica, iron, and alumina. Fly ash is classified as Class F because it has a high concentration of SiO2, Al2O3, and Fe2O3 while OPC has a high CaO value. With the right composition and material preparation, CFA and CBA from the Sultan Azlan Shah Power Plant can be used as a cement replacement in concrete.

Zircon melt inclusion study on the Miocene Miuchi granitoid pluton, SW Japan: A new approach to estimate crystallization pressures of granitic rocks

Granitic rocks (sensu lato) are a major rock type in orogenic belts. The crystallization pressures of granitic rocks can help to unravel the magmatic processes and tectonic evolution of these regions, particularly in areas where metamorphic rocks are not exposed. However, geobarometric techniques that are suitable for granitoids are quite limited. In this study, we propose a new approach to estimate crystallization pressures of granitoid magmas using melt inclusions in zircon, a ubiquitous accessory mineral in these lithologies. Homogenization experiments of polymineralic inclusions hosted in zircon have been conducted from a biotite granite sample in the Miocene Miuchi pluton, southwest Japan arc, using a piston-cylinder high-pressure–high-temperature apparatus. The homogenized compositions of the inclusions have high SiO2 contents (76–80 wt%) implying that they represent fractionated interstitial melts trapped in growing zircon crystals. The rhyolite-MELTS geobarometer for the homogenized melt inclusions in oscillatory-zoned zircon rim yields pressures ranging from 80 to 114 MPa (with error of ±25 MPa), interpreted as the crystallization pressures of the Miuchi pluton. These results are consistent with field and petrographic observations suggestive of a shallow emplacement level. The approach presented here would be applicable to most granitoids, which could provide fundamental data to better understand granite petrogenesis and the tectonic evolution of orogenic belts.

Multiple ridge subduction processes in the southern Altaids: Implications from clinopyroxene chemistry and Sr–Nd–Hf isotopes of late carboniferous Nb-enriched, magnesian diorite-andesites in West Junggar, NW China

Magnesian (Mg# > 45) and/or Nb-rich (Nb > 6 ppm) dioritic-andesitic rocks have been identified in the Mayile area of southern West Junggar, Northwest China. A systematic petrological, geochronological, whole-rock geochemical, Sr–Nd–Hf isotope, and clinopyroxene chemistry study was conducted to constrain the petrogenesis, mantle source, and P–T conditions of magmas as well as the tectonomagmatic processes in the southern Paleo-Asian Ocean subduction zone. Mayile dioritic-andesitic rocks generated in the Late Carboniferous (306–312 Ma) have a high SiO2 content (52.3–63.2 wt%) and high Mg# (46–66) as well as sanukitic-like low LaN/YbN and Sr/Y ratios. They have high Nb contents (6.27–11.6 ppm) and Nb/U (9–18) ratios and are Nb-enriched sanukitic high-Mg andesites (HMAs). Clinopyroxene thermobarometry indicates that the parental magma of the Mayile HMAs experienced a high-temperature (1137–1199 °C) and shallow-level (0.8–0.17 GPa) partial melting in a mantle wedge. They have εNd(t) (+5.14 to +6.42), εHf(t) (+8.8 to +14.4), and zircon εHf(t) (+9.4 to +15.8) values and a slightly high (87Sr/86Sr)t ratio ranging from 0.703214 to 0.704140 relative to normal mid-ocean ridge basalt (N-MORB). The results suggest that West Junggar was dominated by continuous records of sanukitic rocks hinting at multiple ridge subduction processes in the southern Altaids. We reconstructed the subduction history of the Junggar Ocean in the Carboniferous-Permian from these particular observations in West Junggar, and gained insight into the gradual evolution of the tectonic setting, which transitioned from normal intraoceanic subduction to hot subduction of the young oceanic lithosphere from the Early to Late Carboniferous, with subsequent ridge subduction occurring mainly in the Late Carboniferous.

Petrogenesis, tectonic setting and geodynamic implications of keziergayin granites in the kelan basin (Chinese Altai): constraints from geochemistry, zircon U-Pb geochronology and Nd‒Hf‒Pb‒O isotopes

The Chinese Altai is characterized by abundant granitoids, which not only are indicators of the interaction between crust and mantle but also provide critical constraints on the tectonic evolution of the orogen. This study presents zircon U‒Pb‒O isotopes, whole-rock major and trace element and Nd‒Hf‒Pb isotopes data for granite porphyries from the Keziergayin region in the Kelan Basin. The granite porphyries intrude in the Kangbutiebao Formation with zircon U‒Pb dating of 394 ± 3 Ma. They have the characteristics of subalkaline and metaluminous to weakly peraluminous and show geochemical affinity with I-type granite. The granite porphyry samples display negative εNd(t) (−1.9 to −1.4), positive εHf(t) (+4.3 to +11.4) values, with Nd–Hf decoupling; low Pb isotope compositions; δ18OV-SMOW (6.38‰–8.45‰) is less than 10‰, within the range of O isotopes of medium-basic igneous rocks. These geochemical signatures indicate that the granite porphyries originated from lower crust medium−basic igneous rocks extracted from the lithospheric mantle metasomatized by subducted melt. They are characterized by high SiO2 contents and Rb/Sr ratios; low CaO contents and K/Rb ratios, hinting that they were formed by highly evolved magmas, with fractionation crystallization of feldspar, apatite, garnet, allanite and/or monazite. The granite porphyries possess positive Rb, Th, U, Nd, Zr, Pb and light rare Earth elements (LREEs) anomalies with strong negative Ba, Nb, Ta, Sr, P, Ti and Eu anomalies, implying that their formation were related to an island arc. Combined with previous studies, it is suggested that the existence of the Early Devonian arc-basin system associated with subducting slab rollback in the Chinese Altai, which belongs to the Siberian active continental margin system.

Effect of curing temperatures on geopolymerization and heavy metal solidification in alkali-activated zeolite/MSWI fly ash specimens

Admixtures of pozzolanic materials or solid wastes with municipal solid waste incineration fly ash (MSWIFA) can improve heavy metal stabilization/solidification (S/S) properties in alkali-activated MSWIFA specimens. In this work, the compressive strength of MSWIFA admixes with zeolite activated by Na2O·1.7SiO2·nH2O (FZNS) specimens with different curing times (3, 7, 14, and 28 d) and temperatures (20, 50, and 80 ℃) is investigated. The results reveal that a 40 wt% zeolite replacement of MSWIFA in FZNS specimens (FZNS40) not only increases the early compressive strength by 129% but also reduces strength loss during continuous high-temperature (50 or 80 ℃) curing. Moreover, zeolite addition promotes the creation of geopolymers at 28.5°–30.5°in X-ray diffraction (XRD) curves. During 50 or 80 ℃ curing, the NaCl peak disappears and a marginal Friedel's salt peak can be detected at 11.4°. The gel contents are more concentrated on C-S-H in FZNS0 and C-(A)-S-H/N-A-S-H in FZNS40, as demonstrated by differential thermogravimetry (DTG) and magic angle spinning nuclear magnetic resonance (MAS NMR) analysis. With zeolite addition, long-time and high-temperature curing can improve the heavy metal solidification ratio in FZNS specimens. After high-temperature curing, the honeycomb or cluster morphologies of the gel products, visible by scanning electron microscopy (SEM) in the FZNS specimens, reveal high heavy metal stabilization properties. It is easier to form the fibrous C-(A)-S-H/N-A-S-H gel near zeolite owing to the high content of SiO2 and Al2O3. Zeolite modifies the compressive strength, high-temperature stability, and heavy-metal S/S efficiency in FZNS specimens, which promotes the utilization of MSWIFA as an ecologicalresource in the future.

Zircon Hf-O and apatite Sr-O isotopes jointly reveal the origin and mineralization of the Miocene adakitic porphyries in the Gangdese belt

The Gangdese belt is a significant belt for exploring the dynamic processes of continental collision orogeny and mineralization. The impact of petrogenesis and chemical heterogeneity of the E-trending Miocene adakitic rocks in Gangdese porphyry deposit belt on mineralization mechanisms has always been controversial. New whole-rock Sr-Nd isotope, zircon U-Pb dating and Hf-O isotope data, especially integrating apatite volatile (Cl and S) and Sr-O isotope compositions, of the Miocene mineralized porphyries from Lakange deposit can provide the development of metallogenic system origin, as well as magmatic and volatile process. The Lakange granites show adakitic geochemical composition affinity with high potassic calc-alkaline. They have high SiO2 content, low MgO and Ni contents, positive εNd(t) value (0.1 ∼ 0.8), and high (87Sr/86Sr)i ratios (0.705088 ∼ 0.705269), positive zircon εHf(t) (7.6 ∼ 11.2), medium δ18O (4.33‰∼7.27‰) values, combining with apatite Sr-O isotopes (87Sr/86Sr = 0.7040 ∼ 0.7169; δ18O = 7.0‰∼8.2‰), implying that the granites are originated from the partial melting of the juvenile lower crust beneath the southern Lhasa subterrane. The Miocene adakitic rocks of the Gangdese metallogenic belt exhibit spatially isotopically heterogeneity in a west to east direction (87°E-93°E). These variations are attributed to the lower crust modification by the oxidized mantle-derived melts/fluids from metasomatic subcontinental lithospheric mantle in Miocene, resulting in the formation of juvenile lower crust, that thickened the crust and shortened the lithospheric mantle. In-situ Sr-O isotope of apatites identified the oceanic components in the volatile sources, indicating that volatiles existed beneath the Lhasa terrane during Neo-Tethyan oceanic slab subduction prior to the Miocene partial melting of the lower crust. The high volatile concentrations (Cl and S) aid in the transport of metals that produce the Gangdese Miocene porphyry deposits.

Petrogenesis and tectonic implications of the early Paleozoic granites in the Lincang granitic batholith, southwestern China: Constraints from geochronology, geochemistry and Hf isotopes

This study presents the recently discovered Wulao Shan Ordovician granite within the Lincang granitic batholith, discusses its geochemical affinity, genesis, and tectonic significance, and interprets the proto-Tethys orogenic model in southwest Yunnan. LA-ICP-MS zircon U-Pb analyses indicate a crystalline age of 473.0 ± 2.9 Ma for the Wulaoshan gneissic granite. Geochemical analyses show that the Wulaoshan granite exhibits relatively high SiO2 concentrations (73.4–77.3 wt.%), strong peraluminous properties (ASI > 1.1), strongly Eu-negative anomalies, light and heavy rare earth fractionation, and relative Ba, Nb, Ta, Sr, P, and Ti depletion. SiO2 and P2O5 exhibit a strong negative correlation, whereas Rb and Y-Th with a positive correlation. The magmatic zircons have negative εHf(t) values of -5.47∼2.74. Petrographic observations and whole-rock geochemical and isotopic analyses imply no aluminum-rich minerals such as cordierite, indicating that the Wulaoshan granite is a highly fractionated, high-temperature I-type granite, which may have formed via partial melting of the magnesian-iron igneous crust. Additionally, K-feldspar, plagioclase, and biotite within the granite samples may have undergone intense fractional crystallization. The Wulao Shan gneissic granite is an arc granite associated with subduction, indicating that the Lincang Block underwent proto-Tethys subduction. This finding provides evidence for proto-Tethys subduction down to the Lincang-Simao block and further supports the bidirectional subduction model of the proto-Tethys.

Chronolgy and Geochemistry of the Sijiaying Iron Deposit in Eastern Hebei Province, North China Craton: Implications for the Genesis of High-Grade Iron Ores

The Sijiaying iron deposit is located in the Eastern Hebei area of the southern section of the northern margin of the North China Craton (NCC) and is the largest single iron deposit in China. The deposit contains many banded iron formations (BIFs) and was proven to have more than 3 million tons of high-grade iron ore resources. This study carried out geochemistry and zircon U–Pb analysis of normal-grade iron ore, high-grade iron ore, and wall rock (biotite–leptynite, chlorite–sericite schist) in the Sijiaying deposit and discussed the genesis and metallogenic age of high-grade iron ore. BIFs have low concentrations of Al2O3 and TiO2 and high field strength element (HFSE) depletion, indicating almost no contamination via terrestrial debris. The standardized post-Archean Australian shale (PAAS) rare earth element (REE) distribution pattern indicates that the iron formation exhibits positive Eu, Y, and heavy rare earth element (HREE) anomalies and lacks negative Ce anomalies, indicating that the Sijiaying BIF was enriched with iron sources via high-temperature hydrothermal fluids from the seabed and deposited in an anoxic ancient marine environment. In addition, geological field work identified two types of high-grade iron ore in the mining area: primitive sedimentary and hydrothermally altered high-grade iron ore. Further ore geochemical research showed that the primitive sedimentary-type iron ore is similar in geochemistry to the BIF. In addition to low Eu/Eu* values, the hydrothermally altered high-grade iron ore shows geochemical characteristics similar to those of the BIF, suggesting that they share the same iron source but did not form at the same time. The total large ion lithophile element (LILE) (Sr, Ba, Pb) contents in primitive sedimentary-type high-grade iron ore are higher than those in hydrothermally altered high-grade iron ore, indicating that LILEs are carried away via fluids during the hydrothermal alteration process in normal-grade iron ore. The geochemical characteristics of biotite–leptynite and chlorite–sericite schist include high contents of SiO2 and Al2O3, light rare earth elements (LREEs), LILE enrichment (Rb, Ba, Sr, Zr), and HFSE depletion (Nb, Ta, P, Ti), characteristics that are similar to island arc volcanic rocks. The reconstruction of the original rock indicates that the wall rock is a product of volcanic sedimentary cycles in an island arc setting. Zircon cathodoluminescence images and LA–ICP–MS zircon U–Pb dating can be divided into four age groups (3283 Ma, 2547 Ma, 2500 Ma, and 2407 Ma), which correspond to the earliest volcanic activity in eastern Hebei, the main mineralization age of the Sijiaying BIF (the mineralization age of primitive sedimentary high-grade iron ore), a regional tectonic–metamorphic event, and the occurrence of migmatization (the mineralization age of hydrothermally altered high-grade iron ore), respectively. Therefore, the Sijiaying BIF and primitive sedimentary high-grade iron ores were deposited and mineralized at 2547 Ma, and the iron orebody was later altered via the hydrothermal solution at 2407 Ma, forming large-scale high-grade iron ores.

Geochemical and remote sensing integrated with satellite gravity data of Darhib and Atshan talc deposits, South Eastern Desert, Egypt

The current contribution conducted new geochemical, remote sensing integrated with gravity detailed studies of talc deposits to identify the talc protolith as well as its extension, depth, and structures. There are two examined areas, distributed from north to south, Atshan and Darhib and both belong to the southern sector of the Egyptian Eastern Desert. They occur as individual lenses or pocket bodies in ultramafic-metavolcanics following NNW-SSE and E-W shear zones. Geochemically, among the investigated talc, Atshan samples have high contents of SiO2 (av. 60.73 wt.%), and higher concentrations of transition elements such as Co (av. 53.92 ppm), Cr (781 ppm), Ni (av. 1303.6 ppm), V (av. 16.67 ppm), and Zn (av. 55.7 ppm). Notably, the examined talc deposits contain low contents of CaO (av. 0.32 wt.%), TiO2 (av. 0.04 wt.%), SiO2/MgO (av. 2.15), and Al2O3 (av. 0.72 wt.%), which is comparable with ophiolitic peridotite and forearc setting. False color composite (FCC), principal component analysis (PCA), minimum noise fraction (MNF), and band ratio (BR) have been used to distinguish talc deposits in the investigated areas. Two new proposed band ratios were created to separate talc deposits. FCC band ratios (2/4, 4/7, 6/5) and (4 + 3/5, 5/7, 2 + 1/3) have been derived to focus on talc deposits in two case studies, Atshan and Darhib areas. The application of regional, residual, horizontal gradient (HG), and analytical signal (AS) techniques to gravity data are used in interpreting the structural directions of the study area. The analysis of this technique displays several notable faults trending in NW–SE, NE–SW, NNW–SSE, and E–W directions. Two techniques of gravity depth calculation were applied in the study areas, namely source parameter image (SPI), and Euler deconvolution (EU). The analysis of these techniques reflects that the depth of subsurface sources ranges between 383 and 3560 m. Talc deposits may be attributed to greenschist facies metamorphism or to a magmatic solution that is (associated with granitic intrusions) interacted with the surrounding volcanic rocks forming metasomatic minerals.

Muscovite 40Ar-39Ar and cassiterite U-Pb dating of the Indosinian Aotou quartz-vein type tin deposit, southern China and its geological significance

The determination of deposit age is fundamental in economic geology, while the result is often disappointing because of the difficulties in selection of suitable minerals. In this study, on the base of detailed field investigation, we successfully combined the muscovite 40Ar-39Ar dating and cassiterite LA-ICP-MS U-Pb dating in the Aotou tin deposit, Jiangxi province, South China. The result of the muscovite 40Ar–39Ar plateau ages (228.7 ± 1.5 Ma) and the cassiterite U-Pb lower intercept ages (227.4 ± 6.9 Ma) are consistent, accurately defined that the Aotou tin deposit was formed during late Indosinian. With the gradual discovery of another Indosinian W-Sn deposit, we have taken this opportunity to discuss the prospecting index of the Indosinian granite by compiling data of relevant plutons. The result reflects that the Indosinian metallogenic plutons are mainly acidic rocks and produced in the form of small rock mass, with index minerals of muscovite and volatile-rich minerals such as tourmaline and fluorite. Geochemically, they show that the higher SiO2 content (71.51–78.14%), A/CNK (1.13–1.66), Rb/Sr (21.94 in average), but lower Nb/Ta (4.03 in average) and ΣREE (85 ppm in average), which could be useful indexes for identifying the metallogenic pluton. Furthermore, the negative correlation between SiO2 and ΣREE, K2O and Na2O can be used as important ore-prospecting indexes, as a result of they indicate the differentiation of ore-bearing hydrothermal fluids.