High Alkali Content Research Articles

Groundwater Pollution Model and Diffusion Law in Ordovician Limestone Aquifer Owe to Abandoned Red Mud Tailing Pit

Red mud is a strong alkaline solid waste pollutant produced in the process of aluminum smelting, which causes great pollution to the regional groundwater environment due to its high content of fluorine and aluminum and high concentration of strong alkali. In this study, fluoride ion was selected as the model contaminant, and a numerical model of the groundwater flow field and solute transport was developed using GMS software to simulate and analyze the migration patterns of fluoride contaminants caused by the red mud pit for the fractured karst geohydrological conditions. The results demonstrated that the groundwater model and flow pattern were mainly controlled by atmospheric precipitation recharge, given flow boundary conditions and leakage of rivers and drains. When the concentration of fluorine pollutants in the red mud yard was 60.0 mg/L, the maximum migration distance of F− in the groundwater of the ordovician limestone aquifer was 473, 1160, 1595 and 1750 m after 1, 5, 10 and 15 years of bottom leakage, and the additional transport distances were 687, 435 and 155 m every 5 years, respectively. The range of F− pollution plume was 0.37 km2, 1.15 km2, 1.95 km2 and 2.14 km2, respectively and the range of newly added pollution plume was 0.78 km2, 0.80 km2 and 0.19 km2, respectively, every five years. Both indicated that with the extension of time, the migration and diffusion rate of pollutants slow down, and the diffusion volume increased first and then decreased. The F− pollution plume spread from the red mud pit to the northeast, which was consistent with the flow of groundwater. The high-concentration pollution plume was mainly distributed in the Ordovician limestone fractured aquifer in the northeast. This study revealed the migration law of red mud pollutants, and provided a scientific decision-making basis for the prevention and control of red mud groundwater pollution in the future.

Petrogenesis of the quartz diorite from the Lietinggang-Leqingla Pb-Zn-Fe-Cu-(Mo) deposit in southern Tibet: Implications for the genesis of a skarn-type polymetallic deposit in the Tibetan-Himalayan collisional orogen

The Lietinggang-Leqingla deposit is a representative skarn-type polymetallic deposit in the eastern of the central Lhasa subterrane. It comprises Pb-Zn and Fe-Cu-(Mo) mineralization that are part of the same metallogenic system. Garnet-skarn hosting Fe-Cu-(Mo) mineralization distributed in the contact zone between the Jubuzhari complex intrusions and carbonate strata of the Mengla Formation. The Pb-Zn mineralization is hosted in distal garnet-pyroxene and pyroxene-actinolite skarns, which formed in the strata of Mengla Formation. Here, we investigate quartz diorites (61.06 ± 0.93 Ma) that are related to Fe-Cu mineralization in the northern part of the mining area. The quartz diorites are characterized by low SiO2 (61.57–65.88 wt%), low K2O (2.53–3.07 wt%), and high total alkali (Na2O + K2O) contents (5.69–6.35 wt%). They are enriched in large-ion lithophile elements and light rare earth elements, but depleted in high field strength elements and heavy rare earth elements. The quartz diorites yield variably low (La/Yb)N ratios (4.29–7.07, the average value is 6.36) with moderately negative Eu anomalies (Eu/Eu* = 0.49–0.72). Furthermore, they exhibit a narrow range in (87Sr/86Sr)i ratios (0.706355–0.706807) and weakly negative εNd (t) (−2.08 to −1.57), and positive εHf (t) (+0.14 to +3.46) values. Based on the geochemical characteristics presented in this study and previously published data, we propose that the ore-forming rocks related to Fe-Cu and Pb-Zn mineralization were formed at the same time. The intermediate intrusions associated with Fe-Cu mineralization were derived from partial melting of lithospheric mantle mixed with the rejuvenated lower crustal melts, after which the mixed magma underwent minor fractional crystallization during upwelling. The felsic intrusions associated with Pb-Zn mineralization were formed by melting of mantle-derived basaltic magmas with old lower crust component contributions and which underwent extensive fractional crystallization.

Preparation and hydration mechanism of aluminum formate/aluminum sulfate based alkali-free composite accelerator for sprayed concrete

The high alkali content of alkaline accelerators has a negative influence on the late strength and durability of concrete. Further, their corrosive nature is harmful to the skin of construction personnel, posing safety concerns. Therefore, the development of alkali-free accelerators has gained interest, especially in shotcrete-based constructions. The production process of aluminum-sulfate-based alkali-free accelerators is simple and less exothermic, with no negative impact on the later strength of concrete, aspects that are widely recognized and very important in construction. However, their high sulfate content may have a significant impact on the durability of concrete; therefore, reducing the sulfate content plays an important role in enhancing the durability of concrete. In this study, an alkali-free liquid accelerator was synthesized by replacing aluminum sulfate with aluminum formate, which effectively reduced the sulfate content. Experiments were performed on concrete samples in which aluminum sulfate was replaced with aluminum formate at different levels. The results showed that the formate and 3CaO·Al2O3 (C3A) of the alkali-free liquid accelerator prepared from aluminum formate form calcium aluminate, similar to the ettringite phase. The formate promoted the dissolution of Ca3SiO5 (C3S), thus accelerating the hydration of concrete. Meanwhile, aluminum ions hydrolyzed by aluminum formate also participated in the reaction, resulting in the dual participation of cations and anions in hydration, leading to a synergistic effect with aluminum sulfate.

A Late Jurassic A-type granitic-magmatic belt in the westernmost Northeast China and its tectonic implications

The Late Jurassic tectonic environment of the Erguna-Xing'an blocks (in western Northeast China) remains poorly understood due to the complications arising from supposedly superimposed impacts on activities associated with the Mongol-Okhotsk Ocean and the Paleo-Pacific Ocean tectonic regimes. The present work investigated the latest Jurassic A-type granite (Chaganhada granite) in the southwestern Xing'an block. The Chaganhada granite was emplaced at 148 Ma. According to the observations made with the zircon saturation thermometer, the Chaganhada granitic magma has a greater magmatic temperature (>855 °C) than common I-S type granites. In addition, the geochemical characteristics of Chaganhada granite suggest the magmatic affinity of A1-type, which can be supported by high total alkalis contents (8.55%–9.50%), Zr + Nb + Ce + Y values (380–602 ppm), and 10,000*Ga/Al ratios (2.74–3.22), and low Y/Nb ratios. Low CaO + FeO + MgO + TiO2 values, CaO/(FeOt + MgO + TiO2) and K/Rb ratios and initial 87Sr/86Sr ratios (0.7048–0.7055), positive εNd(t) values (0.90–1.22), and zircon εHf(t) values (1.2–5.1) were also observed in the Chaganhada granite. Hence, the study suggests that the latest Jurassic Chaganhada A-type granite might have originated from the crustal quartz-feldspathic igneous sources. Additionally, we approximately restrict a NE-SW trending Late Jurassic A-type granitic magmatic belt in the westernmost part of NE China using data collected by this study as well as publicly available data related to zircon ages, geochemical compositions, and location of the igneous rocks in NE China. Based on the observations above, the current study infers that a Late Jurassic intense extension impacted the westernmost NE China, presumably associated with the orogenic collapse following the closure of the western part of the Mongol-Okhotsk Ocean.

Identification of Potential Pathways of Morella cerifera Seedlings in Response to Alkali Stress via Transcriptomic Analysis.

Alkali stress, a type of abiotic stress, severely inhibits plant growth. Only a few studies have investigated the mechanism underlying the transcriptional-level response of Morella cerifera to saline-alkali stress. Based on RNA-seq technology, gene expression differences in the fibrous roots of M. cerifera seedlings exposed to low- and high-concentration alkali stress (LAS and HAS, respectively) were investigated, and the corresponding 1312 and 1532 alkali stress-responsive genes were identified, respectively. According to gene set enrichment analysis, 65 gene sets were significantly enriched. Of these, 24 gene sets were shared by both treatment groups. LAS and HAS treatment groups exhibited 9 (all downregulated) and 32 (23 downregulated) unique gene sets, respectively. The differential gene sets mainly included those involved in trehalose biosynthesis and metabolism, phospholipid translocation, and lignin catabolism. Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed that M. cerifera seedlings were specifically enriched in stilbenoid, diarylheptanoid, and gingerol biosynthesis; phenylalanine, tyrosine, and tryptophan biosynthesis; and sesquiterpenoid and triterpenoid biosynthesis. Moreover, the related genes involved in hormone signaling pathways and transcription factors were determined through a localization analysis of core abiotic stress pathways. These genes and their molecular mechanisms will be the focus of future research.

Stable zirconium isotopic fractionation during alkaline magma differentiation: Implications for the differentiation of continental crust

Stable Zr isotopes have shown great potential in tracing magma differentiation. However, it remains unclear if different magmatic systems have similar Zr isotopic evolution patterns. Here we report high-precision Zr isotopic compositions of the well-defined Shidao alkaline complex (SAC), eastern China, which show small but important differences from the Hekla tholeiitic volcanic suite, Iceland. The SAC comprises monzodioritic, syenitic, and granitic intrusions with high alkali contents, representing a magmatic suite produced by various degrees of cognate magma differentiation. From mafic to felsic samples, the Zr concentrations and Zr/Hf ratios increase first and then decrease significantly at the inflection of ∼65 wt% SiO2, suggesting zircon saturation started at ∼65 wt% SiO2 during magma differentiation. The δ94Zr values (permil deviation of the 94Zr/90Zr ratio from IPGP-Zr standard) remain nearly constant at ca. +0.01‰ in samples with SiO2 < 65 wt% but then gradually increase with SiO2 in more felsic samples (from +0.05 to +0.63‰), indicating that the Zr isotope fractionation also occurs at ∼65 wt% SiO2. The Shidao alkaline and Hekla tholeiitic suites show zircon saturation at SiO2 ∼ 65 wt%, but their Zr isotopic evolution paths differ. The alkaline suite increases more slowly in δ94Zr compared to the tholeiitic one, with the former reaching the same δ94Zr value at SiO2 higher by ∼5 wt%. Our findings represent the first observation of differences in Zr isotopic evolution from different igneous systems (tholeiitic versus alkaline), which should be considered when interpreting Zr isotopic data of samples out of context, such as detrital zircons or sedimentary samples. Based on the more sluggish Zr isotopic enrichment in the alkaline series than the tholeiitic one, we re-interpret the Zr isotopic composition of the upper continental crust, which may simply be not felsic enough to be isotopically heavier.

Metabolic alkalosis in hemodialysis patients.

Hemodialysis solutions typically contain a high alkali concentration designed to counter interdialytic acidosis, but this could result in persistent alkalosis in some patients. The prevalence and significance of persistent alkalosis were therefore examined at four outpatient centers over a 10-year period. Alkalosis was defined as a pre-dialysis serum [HCO3 ] ≥ 26 meq/L in >6months of a 12-month period and was persistent if present in a majority of months thereafter. Control patients had a serum [HCO3 ] of 19-23 meq/L >6 of every 12 months. Standard, citrate-containing dialysate was used in all patients without adjustment of bicarbonate concentration. 444 of 1271 patients had alkalosis that persisted in 73. Compared to control patients, persistently alkalotic patients were older, but gender, race, starting weight, comorbidities, and mortality did not differ. Dialysis dose was 7% greater, protein catabolic rate was 11% lower, and interdialytic weight gain was 29% lower, all p<0.001. Persistently alkalotic patients had double the incidence of cardiac arrhythmias (p=0.07) and a 20% greater intradialytic blood pressure decrease (p<0.001). Alkalosis is common in hemodialysis patients and can be persistent, likely due to decreased protein catabolic rate and increased dialysis dose, and may have detrimental cardiovascular effects.

Purification of Low-Concentration Carbonyl Sulfide by Red Mud-Based Adsorbent.

Bauxite residue, also known as red mud (RM), is a kind of industrial solid waste with high alkali content, complex composition and difficult utilization. In this study, a new type of RM-based adsorbent was prepared by using polyethylene glycol modified RM and was used to remove low concentration of COS in flue gas. The optimum preparation conditions of adsorbent and the optimum technological parameters of COS adsorption purification were investigated. Under the optimal conditions, the adsorption efficiency of the new adsorbent exceeds 95%, and the COS adsorption capacity reaches 63.56mg/m3. The characterization results showed that the main active components of the adsorbent were active alkali, FeOOH and Fe3O4, and the main products were Na2S2O3, Na2SO4, FeS and FeS2.

Ta-Nb mineralization in the shallow-level highly-evolved P-poor Shihuiyao granite, Northeast China

The Shihuiyao granite district in the southern Great Xing'an Range, Northeast China, is a newly discovered area of rare-metal-bearing granites (RMG). The latest Jurassic Shihuiyao granitic pluton, emplaced into the Lower Permian Linxi Formation, comprises porphyritic granite, leucogranite, and amazonite-bearing pegmatite, all enriched in rare metals (mainly Ta, Nb, Rb). The Shihuiyao granites are peraluminous (A/CNK = 1.02–1.27), characterized by high contents of SiO2 (69.4–78.0 wt%), Al2O3 (12.7–16.9 wt%) and total alkalis (6.8–12.8 wt%), enriched in Ta, Nb, Rb, Cs, and Sn, but depleted in Ba and Sr. They have strong negative Eu anomalies (Eu/Eu⁎ = 0.02–0.42) and show the M-type REE tetrad effect. Low Nb/Ta (<4) and Zr/Hf (<8) values indicate high degree of magmatic fractionation. Whole-rock and mineral compositions variations indicate that the Shihuiyao granites are a typical low pressure and P-poor RMG, which experienced intensive magmatic fractionation followed by intensive hydrothermal reworking. The narrow range of δ7Li values (−0.86‰ to 0.88‰) and Rayleigh distillation modeling suggest that the porphyritic granite and leucogranite represent products of the same magma source, but evolved independently at depth. LA-ICP-MS UPb dating of monazite from the porphyritic granite and leucogranite yield lower-intercept ages of 150.2 ± 0.6 Ma and 147.0 ± 1.7 Ma, respectively. The 40Ar39Ar plateau ages of mica from leucogranite (146.3 ± 1.1 Ma) and an ore-bearing quartz vein (145.6 ± 1.0 Ma), and the UPb age of columbite (146.7 ± 4.7 Ma) further identify this as a latest Jurassic magmatic-hydrothermal mineralization event in NE China. Rapid crystallization and chemical quenching of magma resulted in neutralization of the acid fluoride solution, and a loss of the fluoride ligand during fluid evolution. This further triggered the subsequent crystallization of NbTa oxides. As revealed from geochemical and textural characteristics of the columbite group minerals, the high-degree of fractional crystallization and Ta-rich hydrosilicate fluid metasomatism are the main factors leading to the enrichment of TaNb within Shihuiyao RMG. In general, we conclude that rare metal-hosted magmatism took place in two episodes in NE China, namely, (i) Latest Jurassic to Early Cretaceous (150–130 Ma) peraluminous to metaluminous Ta-Nb-Sn-W RMG, and (ii) Early Cretaceous (130–120 Ma) alkaline Nb-Ta-Be-REE-Zr RMG, which highlight the prospecting fertility for Nb-Ta-REE (SnW) mineralization in NE China.

Determination of transition metal ions in fossil fuel associated wastewaters using chelation ion chromatography

This study outlines the development and subsequent validation of a method using chelation ion chromatography (CIC) pretreatment followed by traditional ion chromatography (IC) and post column UV/vis detection to measure transition metals in fossil fuel wastewaters, such as oil & gas (O&G) brines and coal mine drainage (CMD) waters. Measurement of transition metals is often an important characterization step in the research of environmental and energy systems. IC represents one way to measure these metals with the advantages of being versatile, simple and relatively low cost compared to other analytical methods. However, high concentrations of alkali and alkaline earth metals present in fossil fuel wastewaters will decrease IC detectability of transition metals in these waters. In this study, a CIC method was developed for the analysis of transition metal ions (Fe3+, Cu2+, Ni2+, Zn2+, Co2+, Mn2+, and Fe2+) in fossil fuel associated wastewaters such as Appalachian CMD and O&G wastewaters from the Permian and Bakken shale basins in the United States. CIC system incorporated an on-line chelator column (e.g., the MetPac CC-1) with high selectivity for transition metals over alkali and alkaline earth metals for salt matrix removal prior to transition metal separation and detection. Additional method developments also included acidifying all samples to 2% v/v HCl and using gradient elution rather than isocratic. The recoverability of transition metals in simple salt solutions commonly found in CMD and brine samples (e.g. NaCl, Na2SO4, CaCl2) using CIC was evaluated and compared to that using traditional IC. Our results found that the CIC system significantly improved transition metal recoveries for samples in 10,000 mg/L CaCl2 matrix, reaching 87%-108% recovery for all analytes, as opposed to 2–323% recovery in traditional IC. The limits of detection in this study achieved 10.09–161.2 μg/L, comparable to reported values in similar IC studies. The developed method was also verified with certified water samples, resulting in 89%–111% recoveries in samples with higher analyte concentrations (i.e. >4x the LoDs). The developed method achieved 87%–112% recoveries for most analytes in CMD samples and 72%–138% recoveries for Bakken shale samples, relative to ICP-MS values. Overall, the current IC method can be a very good screening tool for fast and cheap analysis for transition metals at mg/L level, to facilitate selection of samples for more detailed ICP-MS analysis.

Petrography and geochemistry of granitoids and related rocks from the pre-Neogene basement of the Slavonia-Srijem Depression (Croatia)

The pre-Neogene basement of the Slavonia-Srijem Depression (eastern Croatia) is composed of various types of igneous, metamorphic and sedimentary rocks. Here we present the petrography and geochemistry of a heterogenous group represented by two types of alkali granite, granite, syenite, rhyolite and orthogneiss. The alkali granite type 1 has an A-type geochemical affinity: a ferroan character, high alkali content, high concentration of rare earth elements (REE3+), Rb, Zr, Nb and Y, and low CaO, MgO, P2O5, Ba, Sr and Eu contents. The syenite has similar characteristics, but displays enrichment in Ba, K, Eu and Zr, which could be a consequence of feldspar and zircon accumulation. The alkali granite type 2 is an A-type granite but differs from the alkali granite type 1 in having lower K2O and Rb, accompanied by higher Na2O and Sr concentrations, possibly resulting from alteration or a different parental magma/evolutionary process. The granite and rhyolite are distinguished from both types of alkali granite by their magnesian character, lower Zr, Nb and Y concentrations, less pronounced Eu negative anomaly, as well as higher Ba, Sr and LREE/HREE. The orthogneiss displays differences in major element chemistry compared to the alkali granite type 1, but has similar trace element and REE patterns. The alkali granites are characterized by Y/Nb&lt;1.2, indicating an ocean island basalt-like source, while the granite originated from melting of a crustal, probably metasedimentary source. The A-type granites could belong to the Late Cretaceous A-type magmatism of the Sava Zone, while the granite is significantly different from the Sava Zone A-type granites as well as the other rocks investigated in this study.

Petrology of Mt. Kıra continental alkali lavas with arc-like signature, Batman, SE Anatolia, Turkey: Evidence for mafic juvenile lower crust assimilated intraplate basalts in the collision- and mantle flow-driven geodynamic setting of Arabian Foreland

Mineral phase variations and compositions of Early Pliocene (40Ar39Ar ages ranges 5.092 ± 0.030–4.892 ± 0.024 Ma) continental alkali basalts cropped out on Mt. Kıra, NE of Batman Province, SE Anatolia, and located approximately 75 km east of well-known Karacadağ Volcanic Complex (KVC) in Diyarbakır Province, record indications of pre-eruptive assimilation of the lower crust by OIB-like basaltic magmas from Arabian Foreland, which are proved by available data of juvenile lower crustal xenoliths in northern Syria Cenozoic basalts. Diopsitic augites with low Mg#’s (0.65–0.73) in Mt. Kıra basalts depict a compositional prone to clinopyroxenes (Mg#, 0.60–0.76) in Syrian lower crustal xenoliths and coexist with Ca- and Mn-rich fayalitic olivines (Fo63–36), Ca-poor (An72–13) plagioclases, and FeTi oxides. Mt. Kıra lavas, classified as hawaiites, are characterized by the narrow ranges of low SiO2 (46.30–47.68 wt%), Al2O3 (13.74–14.41 wt%), MgO (3.48–4.16 wt%), and high total alkali (Na2O + K2O, 5.26–5.89 wt%), Fe2O3 (13.97–15.38 wt%), TiO2 (3.44–3.61 wt%), CaO (7.20–8.99 wt%), and P2O5 (1.54–1.71 wt%) contents, and with low Cr (< 14 ppm) and Ni (< 20 ppm) values. Except for unusual ZrHf depletion, they exhibit typical arc-like (or crust-like) sharp negative anomalies of NbTa and Ti and possess high concentrations of Y (45–51 ppm), Sc (28–33 ppm), and Heavy REE (e.g., Dy, 9.25–10.73 ppm; Er, 4.74–5.27 ppm; Yb, 3.79–4.44 ppm). Two-component mixing model, and radiogenic 87Sr/86Sr (0·7,044,010–0.705396) and 143Nd/144Nd (0.512676–0.512812) isotopic compositions, which overlap with bulk-silicate earth, for Mt. Kıra basalts, provide evidence for the mafic juvenile lower crustal assimilation by OIB-like basaltic magmas derived from a common enriched mantle source. High Ba/La, Ba/Ta, Ba/Nb, Zr/Nb, and low Nb/La, La/Sm, Nb/Th, La/Yb, and Dy/Yb ratios, which coincide with those of Syrian lower crustal xenoliths, appears as geochemical hallmarks for decoupling of juvenile lower crust assimilated Mt. Kıra, NW Syria and some of KVC basalts from least contaminated ones in Arabian Foreland. The enrichments in Y, Fe, and Ti and depletions in Al and Sr in Mt. Kıra lavas, however, are attributed to post-eruptive chemical weathering processes. Based on petrological and tectonic data, it is proposed that the northern Arabian Foreland Cenozoic volcanism was triggered by the combined effect of both collision- and mantle flow-driven forces with a kinematic linkage. Asthenospheric mantle flow and upwelling, which supply a thermal source, caused the deep mantle processes and interaction between asthenosphere and lithosphere, which was formed the amphibole-bearing garnet lherzolitic (asthenospherized) metasomes (mantle flow-induced metasomatism) at the base of the SCLM accreted from the ductile asthenosphere, prior to partial melting. Partial melting of such re-fertilized metasomes and surrounding wall rock was most likely produced hybrid parental magmas via mixing variable proportions of melt fractions from a garnet lherzolite source with melt fractions from an amphibole-bearing garnet lherzolite source. On the other hand, concurrently running of collision-induced temporarily changing regional stress -compressional or extensional- regimes caused i) the development of surface tectonic structures in a dynamic topography that reactivated the pre-Neogene deep tectonic structures, ii) multiphase rapid uplifts, and iii) prominent deep channeling for the upwelling enriched mantle-derived hybrid magmas to penetrate. The shallow level lower crustal assimilation of this OIB-like hybrid mantle melts, generated the Mt. Kıra, NW Syria, and some of KVC basalts in the Arabian Foreland, during magmas en route to the surface.

Implications for Metallogenesis and Tectonic Evolution of Ore-Hosting Granodiorite Porphyry in the Tongkuangyu Cu Deposit, North China Craton: Evidence from Geochemistry, Zircon U-Pb Chronology, and Hf Isotopes

The Tongkuangyu copper deposit in Zhongtiaoshan at the southern margin of the North China Craton is one of the oldest porphyry Cu deposits in the world and its metallogenesis and tectonic evolution have been debated. Here, porphyritic intrusion geochemical and geochronological data are reported to identify the diagenetic age, mineralization, tectonic setting, and evolution of the deposit. Geochemical data show that granodiorite porphyry is a peraluminous rock, with low concentrations of Fe (~3.99%) and Ti (~0.29%) and high concentrations of alkali (~6.13%) and high Al (~15.42%) and Mg numbers (~51). The rocks show comparative enrichment of Na, K, and Mg; higher La/Yb ratios, no significant Eu anomaly, and obvious Nb–Ta–Ti negative anomaly, showing similar geochemical characteristics to Archean TTG and sanukitoid. ΣREE vary greatly, ranging from 33.47 × 10−6 to 277.81 × 10−6 (average 137.09 × 10−6). The characteristics of REE show obvious fractionation of LREE and HREE, enrichment of LREE, and depletion of HREE. Some of the LREE (La and Ce) and LILE (K, Rb, and Ba) are enriched, but some of the LILE (Th and U) are depleted. In addition, some of the HFSE (Nb, Ta, P, and Ti) are depleted while some (Zr and Hf) are enriched. High precision LA–MC–ICP MS zircon U–Pb dating yield concordant ages of 2159 ± 19 Ma, which is broadly coeval with ore formation (~2.1 Ga) in the area. Zircon εHf(t) values range from −3.8 to 1.13, with a model age of 2778 to 2959 Ma, indicating that the formation of porphyry is related to the partial melting of Archean crust (~2.7 Ga) with a minor amount of mantle material added. Tongkuangyu granodiorite porphyry formed in the tectonic setting of the post-orogenic extension in the Paleoproterozoic, and Tongkuangyu Cu deposit may be related to the extension of the North China Craton in the Paleoproterozoic.

Alkali-Induced In Situ Formation of Amorphous NixFe1-x(OH)2 from a Linear [M3(COO)6]-Based MOF Template for Overall Electrochemical Water Splitting.

Amorphous and bifunctional electrocatalysts based on 3d transition metals tend to exhibit better performance than their crystalline counterparts and are a promising choice for efficient overall water splitting yet far from being well explored. A 3,6-net metal-organic framework (MOF) of [Ni3(bpt)2(DMF)2(H2O)2]·1.5DMF (Ni-MOF), based on linear [Ni3(COO)6] as a node and [1,1'-biphenyl]-3,4',5-tricarboxylic acid (H3bpt) as a linker, was conveniently prepared via a hydrothermal reaction. Benefitting from the wide compatibility of the octahedral coordination geometry in Ni-MOF for different 3d metal ions, the molecular level and controllable metal doping facilitates the production of the desired Ni/Fe bimetallic MOF. A high-concentration alkali solution of 1 M KOH induced the in situ transformation of the MOF as a precursor to new amorphous electrocatalysts of [Ni(OH)2(H2O)0.6]·H2O [a-Ni(OH)2] and its metal-doped derivatives of a-Ni0.77Fe0.23(OH)2 and a-Ni0.65Fe0.35(OH)2. In particular, the costly organic ligand H3bpt was fully dissolved in the alkaline solution and can be recovered for cyclic utilization by subsequent acidification. The obtained amorphous hydroxide was deduced to be loose and defective layers containing both coordinated and lattice water based on combined characterizations of TG, IR, Raman, XPS, and sorption analysis. As opposed to the crystalline counterpart of Ni(OH)2 with stacked packing layers and an absent lattice water, the abundant catalytic active sites of the amorphous electrocatalyst endow good performance in both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The bifunctional a-Ni0.65Fe0.35(OH)2 coated on nickel foam realizes small overpotentials of 247 and 99 mV for OER and HER, respectively, under a current density of 10 mA cm-2, which can work with a cell voltage of merely 1.60 V for overall water splitting. This study provides an efficient strategy for widely screening and preparing new functional amorphous materials for electrocatalytic application.

Ecological geopolymer produced with a ternary system of red mud, glass waste, and Portland cement

In this study, the use of residues from the processing of bauxite and glass powder as precursors for the preparation of geopolymers was evaluated. The route used was an alkaline solution of NaOH with three different molarities. Nine compositions of the percussion (waste) and the activator used were verified. XRF, XRD, laser granulometry, SEM, FTIR, BET, DTG, and compressive strength tests were used to verify the physical and chemical characteristics of the residues used and the geopolymers obtained. Some geopolymers developed efflorescence on their surfaces, indicating a higher alkali content. The compressive strength increased with the addition of small amounts of Portland cement (5%). The composition with the best performance exhibited a compressive strength of 11.35 ± 1.23 MPa after 28 days. The results of the chemical analysis showed the formation of the characteristic gel of the geopolymers. However, the primary finding was that the amount of activator (sodium hydroxide) proved to be inefficient because of the intrinsic alkaline properties of the red mud, which were already effective in the alkaline activation process.

Novel one-part alkali-activated binder produced with coffee husk ash

New alkaline activators to generate alkali-activated binders (AAB) are being studied to reduce common use of sodium hydroxide and sodium silicate due to environmental and safety problems. In this context, a new alkaline activator is proposed from coffee wastes: coffee husk ash (CHA). Coffee husk was calcined at different temperatures (600, 700 and 800 °C) and times (1–10 h) to determine the CHA with best properties for alkaline activator: high alkali content, low organic matter content, and high solubility/pH in water. Results showed that optimum calcination time and temperature were 6 h at 700 °C. Produced CHA presented high K2O content in the form of K2CO3, and CHA generated at 700 °C presented highest solubility/pH in water. This high activity was confirmed in mixtures of CHA with blast-furnace slag (BFS) in one-part AAB, in which hydrated products were detected in pastes through microstructural tests; and compressive strength of mortars yielded 16.4 MPa after 1 day at 60 °C.

Geochemistry and geochronology of quartz monzogabbro – monzodiorite – granodiorites of the Potudan pluton (Volga-Don orogen)

This article presents new and summaries of previously published geochemical and geochronological data on rocks of the Potudan pluton and host granitoids of the Kholhol-Repyevka batholith in the central part of the Don Terrane (DT) of Volga-Don orogen. The host granitoids of the Khokhol-Repyevka batholith are assigned to the Pavlovsk granitoid complex, which is widespread in the southern part of the DT. The studied Potudan pluton rocks are differentiated from quartz monzogabbro to granodiorites. They are ferroan, meta-aluminous, and the K2O content displays their relationship to the shoshonite series. For the intrusive complexes of the Don terrane, it is assumed that an enriched heterogeneous source with high contents of alkalis, LILE (large-scale lithophile elements) and LREE (light rare earth elements) is involved, the mantle component is confirmed by increased of MgO, Cr, Ni, Ti, as well as high Sr/Y ratios, (La/Yb)n, (Dy/Yb)n, indicating the deep origin of magmas. The source heterogeneity could have been provided by subduction events about 2.1 Ga. The U-Pb zircon age of crystallization of the Potudan pluton rocks (using the SHRIMP II instrument) is 2061 ± 5.4 Ma and corresponds to the postcollision event in the junction zone of the Sarmatian and Volga-Ural segments of the East European Craton. Association of Potudan rocks with Pavlovsk granitoids in time and space and also morphological features of zircon from various types of rock suites prove the effect of hybridization process during crystallization of the composite batholith. The new data make it possible to expand our understanding of the evolution of crust of the Don Terrane and geodynamic regims of its formation.

Provenance and tectonic setting of the Gudongjing Group in Beishan Orogen

增生造山带中陆源碎屑岩物源区特征的研究可为解剖造山带结构甚至大陆地壳的形成和演化提供关键证据。北山造山带中部的古硐井群被认为是前寒武纪稳定沉积盖层，是北山造山带存在微陆块的重要依据。本文围绕古硐井群的物源区特征，进行了碎屑颗粒和重矿物统计、全岩主微量元素地球化学分析、碎屑锆石U-Pb年代学和Hf同位素测试。古硐井群碎屑岩的碎屑颗粒多呈棱角状，主要为石英、长石，同时含大量硅质岩碎屑和一定数量的火山岩碎屑；重矿物组成以褐铁矿、锆石、白钛石、尖晶石为主，角闪石、电气石、辉石次之，暗示物源区可能存在蛇绿岩、增生杂岩。全岩主量元素以高硅、高铝、富碱、低锰为特征，结合REE、Cr、Co、Sc和Th等惰性元素含量特征共同指示了长英质的物源区。最年轻的碎屑锆石年龄为443.9±13Ma，表明古硐井群最大沉积时限为晚奥陶世。碎屑锆石的年龄高度集中于470Ma附近，且该区间锆石ε_Hf（t）值多为正值，指示物源区存在大量新生地壳物质。本文推测古硐井群可能形成于增生楔楔顶盆地；研究结果支持北山造山带是古生代持续增生造山的产物这一认识。;The clastic sedimentary rocks in an accretionary orogenic belt may preserve key evidence for understanding the architecture of orogenic belts and even the crustal evolution. The clastic sedimentary rocks of the Gudongjing Group in the middle of the Beishan Orogen is considered to be a set of stable sedimentary caprocks of the Precambrian, and it is also an important basis for the existence of micro-continents in the Beishan Orogen. In this paper, statistics on clastic particle grain sizes and heavy mineral compositions, the whole rock geochemical composition analyses, detrital zircon U-Pb dating, and Hf isotope testing are carried out on the clastic rocks of the Gudongjing Group to reveal their prevenances and tectonic settings. The clastic components of the rocks are mainly composed of quartz, feldspar and rock fragments which are mainly siliceous rock fragments together with a certain amount of volcanic ones. Heavy mineral analysis reveals they mainly consist of limonite, zircon, ilmenite and spinel, followed by hornblende, tourmaline and pyroxene, which indicates the contribution of the accretionary complex materials and ophiolites to their provenance. The whole rock major element compositions are characterized by high contents of silicon, aluminum and alkali, while low in manganese. The contents of the inert elements, such as REE, Cr, Co, Sc, Th, etc., show characteristics of a felsic source area. The youngest detrital zircon age obtained in this study is 443.9±13Ma, indicating that the maximum deposition age of the Gudongjing Group is Late Ordovician. The age of detrital zircons is highly concentrated around 470Ma, and the corresponding zircon ε_Hf(t) values are mostly positive, indicating a large number of new crustal materials have developed in their provenance area. Based on the comparative analysis, it is suggested that these clastic rocks are possiblely formed in a slope basin on the top of an accretionary wedge. The results support the point that the Beishan orogenic belt is the product of a continuous accretion of a Paleozoic orogenic belt.

Alkali-silica reaction resistance versus susceptibility of geopolymer binders

Alkali–silica reaction (ASR) is a deterioration chemical process that causes expansion along with cracking of cement paste and aggregate particles, resulting in concrete degradation. Numerous factors influence ASR including aggregate reactivity, cement alkali content and moisture availability. Due to the high alkali content of the activator, the risk of ASR could be anticipated to be greater in geopolymer concrete than in Portland cement concrete. This article reviewed the susceptibility or resistance of geopolymer binders to ASR deterioration, based on published data in the literature. Generally, the vulnerability of geopolymer binders to ASR expansion is influenced by two factors comprising, the chemical composition of the aluminosilicate precursor and the alkaline activator solution characteristics. It is evident that low-calcium geopolymer binder systems exhibit very much lower ASR expansion than high-calcium geopolymer binders. Moreover, ASR expansion increases with increase in the alkali (M2O with M = Na, K) concentration of the geopolymer binder mixture and declines as the silicate modulus rises SiO2/M2O. Calcium-rich geopolymer binders have a higher risk that may exhibit ASR attack, owing to the formation of the more expansive sodium-calcium-ASR gel.

Campanian transformation from post-collisional to intraplate tectonic regime: Evidence from ferroan granites in the Southern Qiangtang, central Tibet

Ferroan granitoids are typically generated in the extensional tectonic settings, and thus record important geodynamic processes related to crustal and mantle evolution. However, their petrogenesis remains controversial. In this study, we investigated newly identified ferroan granites in the Lake Cona region of the southern Qiangtang subterrane (SQT), central Tibet. We present zircon U–Pb age and Hf–O isotope, whole-rock major and trace element and Sr–Nd isotope, and mineral major element data for these rocks. The Lake Cona granites consist of biotite monzogranite and granite porphyry. Zircon U–Pb dating indicates these rocks were generated in the late Late Cretaceous (ca. 75 Ma). The biotite monzogranites are metaluminous to weakly peraluminous, and characterized by relatively high SiO2 (67.1–68.6 wt%), total alkali (10.4–10.8 wt%), Th (31–46 ppm), light rare earth element (LREE), and Zr + Nb + Ce + Y (421–730 ppm) contents, and high Fe-numbers (0.83–0.91; FeOt/[FeOt + MgO]). These rocks can be classified as alkalic ferroan granites. However, compared with the typical ferroan granitoids generated under relatively anhydrous conditions, the biotite monzogranites have higher Al2O3 (15.9–17.0 wt%) contents, lower 10000 × Ga/Al (2.1–2.5) ratios, and small negative Eu anomalies, suggesting that they were generated by brine-assisted (a fluid with low water activity) crustal anatexis. The biotite monzogranites have (87Sr/86Sr)i = 0.7065–0.7069, εNd(t) = −2.3 to −1.9, δ18O = 6.0–6.6‰, and εHf(t) = +2.1 to +9.3, indicative of a magma source that was a mixture of juvenile and ancient crustal components. The granite porphyries also have high contents of total alkalis (9.9–10.2 wt%) and Fe-numbers (0.87–0.90), and similar Sr–Nd–Hf–O isotopic compositions as the biotite monzogranites, but have higher SiO2 and lower TiO2, MgO, TFe2O3, P2O5, CaO, and REE contents, and larger negative Eu anomalies. These features suggest that the granite porphyries represent the highly evolved biotite monzogranitic magmas that underwent differentiation in the shallow crust. The Lake Cona ferroan granites formed in a post-collisional extensional setting that had additional heat input from the deep mantle. Unlike the early Late Cretaceous that was dominated by calc-alkaline magmatism in the SQT, the occurrence of alkali ferroan granites in the late Late Cretaceous may record the transformation from a post-collisional to an intraplate tectonic regime in the central Tibet.