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Tellurium-rich (Te) adularia-sericite epithermal Au-Ag deposits are an important current and future source of precious and critical metals. However, the source and evolution of ore-forming fluids in these deposits are masked by traditional bulk analysis of quartz oxygen isotope ratios that homogenize fine-scale textures and growth zones. To advance understanding of the source of Te and precious metals, herein, we use petrographic and cathodoluminescence (CL) images of such textures and growth zones to guide high spatial resolution secondary ion mass spectroscopy (SIMS) oxygen isotope analyses (10 µm spot) and spatially correlated fluid inclusion microthermometric measurements on successive quartz bands in contemporary Te-rich and Te-poor adularia-sericite (-quartz) epithermal Au-Ag vein deposits in northeastern China. The results show that large positive oxygen isotope shifts from –7.1 to +7.7‰ in quartz rims are followed by precipitation of Au-Ag telluride minerals in the Te-rich deposit, whereas small oxygen isotope shifts of only 4‰ (–2.2 to +1.6‰) were detected in quartz associated with Au-Ag minerals in the Te-poor deposits. Moreover, fluid-inclusion homogenization temperatures are higher in comb quartz rims (avg. 266.4 to 277.5 °C) followed by Au-Ag telluride minerals than in previous stages (~250 °C) in the Te-rich deposit. The Te-poor deposit has a consistent temperature (~245 °C) in quartz that pre- and postdates Au-Ag minerals. Together, the coupled increase in oxygen isotope ratios and homogenization temperatures followed by precipitation of Au-Ag tellurides strongly supports that inputs of magmatic fluid containing Au, Ag, and Te into barren meteoric water-dominated flow systems are critical to the formation of Te-rich adularia-sericite epithermal Au-Ag deposits. In contrast, Te-poor adularia-sericite epithermal Au-Ag deposits show little or no oxygen isotope or fluid-inclusion evidence for inputs of magmatic fluid.

High-temperature oxidation is a common failure in high-temperature environments, which widely occur in aircraft engines and aerospace thrusters; as a result, the development of anti-high-temperature oxidation materials has been pursued. Ni-based alloys are a common high-temperature material; however, they are too expensive. High-entropy alloys are alternatives for the anti-oxidation property at high temperatures because of their special structure and properties. The recent achievements of high-temperature oxidation are reviewed in this paper. The high-temperature oxidation environment, temperature, phase structure, alloy elements, and preparation methods of high-entropy alloys are summarized. The reason why high-entropy alloys have anti-oxidation ability at high temperatures is illuminated. Current research, material selection, and application prospects of high-temperature oxidation are introduced.

A Na-montmorillonite (Na-MMT) was activated with HNO3 (20 wt.%) solution at various temperatures and times to obtain acid-activated MMT (Acid-MMT). Zinc (4 wt.%) was supported on Acid-MMT via the impregnation method using Zn(NO3)2⋅6H2O as a precursor. The catalytic performance of the Zn/Acid-MMT for the aromatization of heptane was investigated. The amount and distribution of acidity of Acid-MMT, which could be adjusted by changing the acid activation time and temperature, significantly affected the heptane conversion and aromatics content. As a result, an efficient Zn/Acid-MMT catalyst for the aromatization reaction was obtained by optimizing the acid-treatment conditions of Na-MMT.

The middle Jurassic Zhiluo Formation in the Dongsheng is comprised of a big set of green sandstone/mudstone with most of uranium orebodies occurring in close proximity to its footwall. By synthesizing field observations, region analysis, data collected from previous coal and uranium borehole, a regional north-south geological profile across the entire orefield is conducted. Experiments on sandstone/mudstone including rock mineral identification, clastic micromorphology and element geochemistry were carried out. Information from the geological profile indicates that green sandstone/mudstone is widely present in a stable horizon with clear boundaries to the country rock. Microscopic observations and geochemical data on sandstone/mudstone exhibit similar mineral composition with almost identical slightly flat, minor Eu enriched, Ce depleted chondrite-normalized REE patterns. Furthermore, the green clay membrane of the clasts has a complex composition containing chlorite/smectite, green smectite, chlorite, and green kaolinite, with elements including Fe, Mg, Si, and Al. These above results indicate that the green sandstone/mudstone underwent resemble sedimentary diagenetic processes as the country rock without transformation by large-scale regional fluid, while the existence of Fe2+-rich membrane is the main factor to the green sandstone/mudstone. Further concentration of the pre-enrichment uranium during diagenetic process led to the final formation for uranium deposits. The above studies are conducive to enrich the metallogenic mechanism of sandstone type uranium deposits and could provide certain reference for uranium exploration and deployment.

Garnet-bearing mafic granulites occur as lenses within TTG gneiss or metapelite in the Fuping Complex, middle Palaeoproterozoic Trans-North China Orogen. They are composed mainly of garnet, clinopyroxene, orthopyroxene, hornblende, plagioclase, quartz and accessary zircon and titanite. Four stages of metamorphic mineral assemblages have been found in these mafic granulites: (a) the prograde assemblages (M1) are inclusions preserved in the garnet porphyroblasts, including clinopyroxene, hornblende, plagioclase and quartz; (b) the metamorphic peak assemblages (M2) consist of garnet porphyroblasts plus matrix minerals clinopyroxene + orthopyroxene + hornblende + plagioclase + quartz + zircon + titanite; (c) the first retrograde assemblages (M3) are represented by clinopyroxene + orthopyroxene + plagioclase + quartz symplectites rimming the garnets; and (4) the final retrograde assemblages (M4) are hornblende + plagioclase + quartz symplectites rimming or adjacent to the garnets. The retrieved metamorphic P-T paths pass from 530–600 °C/6.5–7.0 kbar (M1) through 680–820 °C/7.2–11.7 kbar (M2) to 730–760 °C/3.2–3.9 kbar (M3) and finally to 600–640 °C/3.2–3.7 kbar (M4). All the P-T paths of the mafic granulites are clockwise, two of these even contain near isothermal decompression (ITD) and subsequent near isobaric cooling (IBC) segments. SHRIMP U-Pb dating of metamorphic zircons of the mafic granulites yields a mean weighted age of ∼1849 ± 9Ma, which is consistent with the metamorphic time of surrounding TTG gneisses. Therefore, the Fuping Complex records the collision event between the Eastern and Western Blocks of the North China Craton that led to the final assembly of this craton during the late Paleoproterozoic.

Geothermobarometry and phase equilibria modeling were conducted for garnet-bearing amphibolite of the Inyoni Shear Zone (ISZ), southwestern Barberton Greenstone Belt, South Africa. The prograde (M1), metamorphic peak (M2) and retrograde (M3) metamorphic P-T conditions were estimated to be ∼560 °C/∼8 kbar, 660–730 °C/7–9.5 kbar and 570–630 °C/5–6 kbar, respectively. The amphibolite records clockwise P-T paths, and the metamorphic peak P-T conditions belong to the medium P/T facies series. The retrograde segment of the P-T path documents near isothermal decompression which may reflect relative fast exhumation. The estimated apparent geotherm is 20–30 °C/km. SIMS U-Pb dating of metamorphic zircon suggests that the metamorphism of the ISZ amphibolite have occurred during ∼3.26–3.22 Ga, and the metamorphic peak might occur at ∼3.24 Ga. Furthermore, 40Ar/39Ar dating of hornblende indicates that the cooling stage might occur at ∼3.20 Ga. It is anticipated that the protolith of the amphibolite of the ISZ may have been involved in a subduction-like tectonic process along with the TTG plutons and was metamorphosed during 3.26–3.22 Ga, then uplifted from within the surrounding TTG plutons at ∼3.20 Ga.

A recent study suggests that the deep dolomites in well Xike-1 located more than 1000 m deep have a very low porosity, and no permeability for most of the samples. Given that the largest oil and gas fields in the South China Sea are all composed of biohermal dolomites while the deep dolomites of Xike-1 serve as the caprock formations rather than the reservoirs, this represents the first discovery and is of great theoretical importance. In this paper, core photos of the tight dolomites are presented. Hand specimens description and systematic porosity-permeability reveal a very low porosity, and no permeability for most of the samples. PLM, SEM and XRPD analysis discovered that the dolostones in the deep tight dolomites are quite large in size and euhedral or subhedral in shape. Alizarin red-stained sections are mostly pink in color and have a full coverage, which are considered as evidence for multiple calcite intrusions after the formation of ankerite dolomites. Biological relict textures are developed. The order degree is medium to low. The dolomites could be the product of penecontemporaneous dolomitization.

Iron (Fe) concentration is a crucial parameter for boiler safety. However, as the working fluid circulation circuits cross each other, and the working fluid operational parameters change over a wide range, monitoring the Fe content and evaluating pipeline safety are very difficult. The mass transfer process of Fe in a complex water circulation system was described by constructing a network calculation model of Fe mass transfer in the steam-water circulation system of a supercritical boiler. The distribution of Fe and the corrosion/deposition rate in the system was calculated and analyzed. The influence of a Fe mass disturbance in single or multiple equipment on the mass distribution of Fe in the system is discussed. The results show that model calculation data is close to the operational data. Under the effect of cyclic mass transfer, both the granular and dissolved Fe cannot be ignored. During one cycle, about 36% of Fe was deposited on the system tube; however, the deposition amount in the steam generator and superheater section accounted for 81.2% of the total deposition amount, and the rest was deposited in the low-temperature pipeline. The influence of disturbance on other nodes in the network is quite different, which provides the possibility of discriminating the location of the disturbance node. The research results can provide a theoretical reference for water chemical control and safety during the operation.

The newly discovered Shangmachang epithermal gold (> 11 t Au; Heilongjiang province, NE China) and Beidagou epithermal tellurium-gold (> 5 t Au) deposits are located at the northeastern margin of the Central Asian Orogenic Belt and are hosted in Early Cretaceous volcanic rocks. At the Shangmachang deposit, gold occurs largely as electrum microparticles (5–120 μm) with a fineness of approximately 401–697 in quartz, calcite, and pyrite. Silver-bearing minerals include electrum, polybasite, and minor argentite. The main mineral paragenetic assemblages consist of pyrite-electrum and galena-polybasite, while the hydrothermal alteration minerals include quartz, calcite, sericite, chlorite, and pyrite. Trace elements in the gangue minerals show that the Al contents of gold-bearing quartz veins are lower than those of pure quartz veins (early stage). Fluid inclusions in quartz and calcite mainly comprise liquid-vapor, and the components contain a liquid phase consisting of Na+, Cl−, and SO42− and a gas phase consisting of N2, CO2, and CH4. The Shangmachang fluid inclusions homogenize at 142.8°–303.0 °C and are of low salinity (0.2–8.8 wt% NaCl equiv.), while the Au mineralization formed at 150°–225 °C. The calcite δ18Ofluid values range from − 17.8‰ to − 13.1‰, and the carbon isotope compositions range from − 8.2‰ to − 4.5‰. Zircon U-Pb dating of the Longjiang Formation andesite yields 119.4 ± 1.9 Ma, and the granite yields 118.6 ± 1.2 Ma, suggesting that local magmatism occurred during the Early Cretaceous. Calcite Sm-Nd dating suggests that the Au mineralization has an age of approximately 113.6 ± 4.0 Ma. At the Beidagou deposit, the main mineral paragenetic assemblages consist of sphalerite-galena-hessite and chalcopyrite-altaite-petzite-hessite, while the hydrothermal alteration minerals include quartz, calcite, anhydrite, chlorite, and pyrite. The components of the fluid inclusions in quartz contain a fluid phase consisting of Na+, K+, Cl−, and SO42− and a gas phase consisting of N2, CO2, CH4, and C2H6. The Beidagou fluid inclusions homogenize at 133.8°–370.1 °C and are of low salinity (0.2–8.7 wt% NaCl equiv.), while the Au mineralization formed at 175°–250 °C. The δ18Ofluid and δDSMOW values of the quartz samples from Beidagou range from − 8.2‰ to − 5.0‰ and − 101.6‰ to − 92.8‰, respectively. The Al contents of gold-bearing quartz veins are higher than those of pure quartz veins. Rb-Sr dating of ore-bearing quartz veins suggests that the Te-Au-Ag mineralization has an age of about 115.5 ± 4.4 Ma. In summary, the interpretation of new data from the geological setting, fluid inclusions, O-H-C isotopes, and geochronology, suggests that the ore-forming fluids predominantly comprised meteoric fluids, while the metal content was derived from a mantle source at both the Shangmachang and Beidagou deposits. A geochemical model suggests that the fluids responsible for quartz deposition had a neutral pH and that adiabatic boiling and mixing triggered the gold, silver and tellurium precipitation. Both Shangmachang and Beidagou are interpreted as low-sulfidation epithermal gold deposits.

The Xisha Block is a minor one in the South China Sea and an important tectonic unit in the northwestern part of the region. Zircon SHRIMP U-Pb ages for three volcanic intrusive core samples from Xike-1, an exploratory well penetrating the bioherms of the Xisha Islands. The core samples are from the Miocene reef carbonate bedrock and are recognized as dark-gray biotite-hornblende gabbro, gray fine-grained biotite diorite, and gray fine-grained granite, respectively. Zircon cathodoluminescence (CL) images and trace Th, U and Pb compositions of the zircons show that these rocks are of volcanic intrusive origin. Zircon SHRIMP U-Pb dating yielded six groups of ages, ranging from 2451-1857 Ma to early Cretaceous, which indicate that the formation and evolution of the Xisha Block was affected by the evolution and closure of Neotethys Ocean, probably within its eastern extension into South China Sea. Both old, deep-sourced material, including fragments from Rodina supercontinent, and recent mantle-derived magma products contributed to the emergence and formation of the Xisha block. The SHRIMP U-Pb results also proved that this process differed from that of the Kontum massif, the Hainan Block, and the South China Block, but is similar to that of the Nansha and Zhongsha blocks. The process was associated with the effects of Yanshanian magmatism induced by subduction mechanisms of the Paleo-Pacific Plate or the reworking of the multiple magmatisms since the Early to mid-Yanshanian, possibly jointly experienced by the Xisha-Zhongsha-Nansha Block.

The newly discovered Daxintun Sb-Au deposit (Heilongjiang province, NE China) is located at the north-eastern margin of the Central Asian Orogenic Belt, and it is hosted by Neoproterozoic to Early-Cambrian two-mica schist and marble. The antimony-bearing minerals include stibnite, famatinite, tetrahedrite, boulangerite, freibergite, and minor andorite. Gold occurs largely as native gold microparticles (0.1–20 μm) with high fineness (974–983) accompanied by quartz, stibnite, calcite and pyrite. Fluid inclusions in ore-bearing quartz and calcite phases mainly comprise liquid–vapor and minor CO2-bearing three-phase types, and the gas phases contain CO2, CH4 and H2S. The Daxintun fluid inclusions homogenize at 111.8–353.4 °C and are of low salinity (0.53–12.51 wt% NaCl equiv.). The δ18OSMOW of the Daxintun quartz falls into a wide range (4.2‰–16.9‰), yet the δDSMOW falls into a narrow range (−108.0‰ to −87.3‰), suggesting that the ore-forming fluids formed from metamorphic fluids that mixed with meteoric water. The stibnite δ34S ranges between −0.9‰ and 5.1‰ (mean = 2.8‰). The stibnite has 206Pb/204Pb of 18.234–18.306, 207Pb/204Pb of 15.537–15.561 and 208Pb/204Pb of 38.103–38.227, implying a metamorphic fluid source. The conditions of gold and antimony precipitation are comprised of neutral pH and fluid mixing, with decreasing fS2 and fO2. Zircon U-Pb dating of the fine-grained Daxintun granite yields a Late-Jurassic age (154.0 ± 2.0 Ma), and the Daxintun diorite dike yields a weighted mean age of 122.1 ± 1.3 Ma. Stibnite Rb-Sr dating suggests that the Sb-Au mineralization has an age of approximately 152.8 ± 2.4 Ma. The observed ore deposit geology, as well as new data on the ore-forming fluids, H-O-S-Pb isotopes, and Rb-Sr geochronology, suggest that the Daxintun Sb-Au deposit is best described as an orogenic type gold deposit that formed during subduction of the Palaeo-Pacific and the Mongolia–Okhotsk Oceans during the Late-Jurassic.

The discrete mafic granulite and amphibolite enclaves within the Pingyang trondhjemitic pluton, Fuping metamorphic terrane, middle Trans-North China Orogen, ubiquitously record three stages of metamorphic assemblages. For the mafic granulite enclaves, the prograde metamorphic assemblage (M1) is represented by mineral inclusions (clinopyroxene + hornblende + plagioclase + quartz ± apatite) preserved in the garnet porphyroblast, the metamorphic peak (M2) assemblage consists of garnet and matrix minerals of clinopyroxene + orthopyroxene + hornblende + plagioclase + quartz ± magnetite ± ilmenite ± zircon, and the retrograde (M3) stage is represented by symplectite assemblage of orthopyroxene + plagioclase ± clinopyroxene ± hornblende ± quartz rimming the garnet porphyroblast. The metamorphic P-T paths of the mafic granulite enclaves are defined to pass from 560–750 °C/6–9 kbar (M1) through 740–880 °C/11–14 kbar (M2) to 720–800 °C/6–8 (M3), indicative of a collisional orogenic process. The metamorphic P-T path of the amphibolite enclave experienced from 670–730 °C/9.3–11.8 kbar to 710–730 °C/3.9–5.5 kbar, further certify such metamorphic feature of an orogenic belt. SIMS U-Pb dating of zircons of the trondhjemitic gneiss yields the magmatic crystallization age of ∼2.52 Ga, and both the trondhjemitic gneiss and the mafic granulite enclaves yield the metamorphic age of ∼1.89–1.86 Ga. Therefore, it can be concluded that the Fuping terrane was involved in the late Palaeoproterozoic subduction-collision-uplifting tectonic process caused by amalgamation of the Eastern and Western Blocks of the North China Craton along the Trans-North China Orogen.

High performance solid electrolytes have been widely used in many devices, such as intermediate temperature (650–850 °C) solid oxide fuel cells, oxygen sensors, super capacitors, etc. In order to solve the problem of phase stability and high grain boundary resistance during the working process, the novel core/shell structure ScSZ nanocomposites were successfully prepared by fractional-precipated method. Non core/shell composites were also prepared by co-precipitation at the same Sc/Zr ratio for comparison. high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Raman characterization were performed to identify the microstructure and phase configuration of the obtained composites. According to HRTEM, clear rich scandia shell layer of 2–4 nm existed at the edge of each core/shell particle. The HRTEM figures of non core/shell composites were homogeneous without the shell structure. XPS element analysis for core/shell composite indicated that scandium ratio increased and zirconium ratio decreased when heat treatment temperature fell. When the heating temperature fell down to 450 °C, scandium ratio reached nearly 35 mol.%. EIS and DC measurement were taken for both kinds of electrolytes to study the electrochemical properties. The ionic conductivity were 178.2 and 154.4 mS/cm at 850 °C for core/shell and non core/shell electrolytes, respectively. The mechanism of conductivity improvement was also studied. It was predicted that the core/shell interface could improve ionic conductivity by modifying the space-charge regions. This result outlines a novel and potential direction for high-end electrolytes to enhance ionic conductivity.

Metamorphic evolution and geochronology of pelitic granulites were reported for the first time in the Taihua metamorphic complex, Mts. Huashan area, southern segment of the trans-North China Orogen (TNCO). Three generations of metamorphic mineral assemblages are recognized: (1) the prograde metamorphic mineral assemblages (M1) are represented by mineral inclusions within the garnet porphyroblasts; (2) the metamorphic peak assemblage (M2) are the garnet porphyroblasts and minerals in the matrix (biotite + orthopyroxene + plagioclase + quartz + K-feldspar + ilmenite + zircon + magnetite); and (3) the retrograde metamorphic mineral assemblages (M3) are represented by the symplectic assemblages around the garnet porphyroblasts, resulted from decomposition reactions between garnet rims and neighboring minerals in the matrix. Calculated by both conventional thermobarometry and pseudosection modeling in the NCKFMASHT system using the Perple_X technique, the P–T conditions of these three metamorphic stages are constrained to be of 4–5 kbar/520–530 °C for the M1 stage, 6.8–8.6 kbar/730–810 °C for the M2 stage and 4.1–6.4 kbar/570–740 °C for the M3 stage, respectively. The derived clockwise P–T paths imply that the Mts. Huashan terrane involved in the subduction and subsequent collision between the Eastern and Western Blocks of the North China Craton (NCC) along the Palaeoproterozoic Trans-North China Orogen (TNCO). High resolution SIMS U–Pb dating of metamorphic zircons reveals the metamorphic ages of 1.85–1.82 Ga. Combined with geochronological data from the literature, it is concluded that the tectonothermal evolution between the Eastern and Western Blocks started as early as ∼1.97 Ga and lasted as late as 1.80 Ga. Furthermore, the eastern Taihua complex records older metamorphic ages and higher peak metamorphic pressures than those of the western Taihua complex, possibly suggesting an eastward subduction model for the TNCO.

Tonalite-trondhjemite-granodiorite (TTG) suite and potassic granite volumetrically expose in the Neoarchean to Paleoproterozoic Taihua complex, Mts. Huashan region, southernmost segment of the Trans-North China Orogen (TNCO). Zircon U–Pb dating on the trondhjemite, granitic gneiss, K-feldspar granite and coarse-grained granite samples show three episodes of magmatism (2.55–2.49 Ga, 2.33–2.25 Ga and 1.87–1.80 Ga) with distinct geochemical features in this area during the Paleoproterozoic. The trondhjemite samples have high SiO2 (67.46–71.73 wt%), Na2O (4.83–5.95 wt%), low Mg# (31–40) and HREE contents, with moderate (La/Yb)N values (16.8 to 35.3) and Sr/Y ratios (15.8 to 34). The potassic granite samples show high SiO2 (65.2–75.43 wt%), K2O (3.9–8.6), low Na2O (1.74–4.17 wt%), Mg# (2–46) and HREE contents, with moderate to high (La/Yb)N values (10.3 to 226) and Sr/Y ratios (12.8 to 208). All these granitoid samples are characterized by high SiO2 and low Mg#, Cr, Ni with moderate to high (La/Yb)N values and Sr/Y ratios. The absence of evidence of any pre-existing high Sr/Y and La/Yb sources in this region led to that the granitoids probably generated from partial melting of hydrous mafic rocks with garnet and amphibole in the residue. Therefore, partial melting of thickened lower curst is the most likely origin. Combined with previous studies, the first episodic magmatism (2.55–2.49 Ga) represented by TTG and granitic gneisses with positive whole rock ƐNd(t) and zircon ƐHf(t) values is interpreted as melts from partial melting of juvenile thickened lower crust. The second episodic magmatism (2.33–2.25 Ga) represented by TTG, granitic gneisses and K-feldspar granite with positive to negative whole rock ƐNd(t) and zircon ƐHf(t) values is suggested as the product of partial melting of both juvenile and pre-existing crustal material. The third episodic magmatism (1.87–1.80 Ga) is represented by these potassic granites, which is synchronism with the metamorphism recorded in this region and probably resulted from partial melting of pre-existing crustal materials in a syn-orogenic or post-orogenic setting during the collision between the Eastern and Western Blocks of the North China Craton. Multistage continental accretion (at 2.84–2.72 Ga, 2.57–2.43 Ga and 2.36–2.25 Ga) and reworking (at 2.36–2.25 Ga, 2.19–2.07 Ga and 1.87–1.80 Ga) occurred in the southern segment of the TNCO from Neoarchean to Paleoproterozoic. Transformation from an Andean-type continental margin arc setting on the western margin of the Eastern Block to continent-arc-continent collision in the southern TNCO during Late Neoarchean to Late Paleoproterozoic is suggested in this paper.

The Dongping gold deposit hosted in syenites is one of the largest hydrothermal gold deposits in China and composed of ore veins in the upper parts and altered zones in the lower parts of the ore bodies. Pervasive potassic alteration and silicification overprint the wall rocks of the ore deposit. The alteration minerals include orthoclase, microcline, perthite, quartz, sericite, epidote, calcite, hematite and pyrite, with the quartz, pyrite and hematite assemblages closely associated with gold mineralization. The phases of hydrothermal alteration include: (i) potassic alteration, (ii) potassic alteration - silicification, (iii) silicification - epidotization - hematitization, (iv) silicification - sericitization - pyritization and (v) carbonation. Mass-balance calculations in potassic altered and silicified rocks reveal the gain of K2O, Na2O, SiO2, HFSEs and transition elements (TEs) and the loss of REEs. Most major elements were affected by intense mineral reactions, and the REE patterns of the ore are consistent with those of the syenites. Gold, silver and tellurium show positive correlation and close association with silicification. Fluid inclusion homogenization temperatures in quartz veins range from 154 °C to 382 °C (peak at 275 °C–325 °C), with salinities of 4–9 wt.% NaCl equiv. At temperatures of 325 °C the fluid is estimated to have pH = 3.70–5.86, log fO2 = − 32.4 to − 28.1, with Au and Te transported as Au (HS)2− and Te22 − complexes. The ore forming fluids evolved from high pH and fO2 at moderate temperatures into moderate-low pH, low fO2 and low temperature conditions. The fineness of the precipitated native gold and the contents of the oxide minerals (e.g., magnetite and hematite) decreased, followed by precipitation of Au- and Ag-bearing tellurides. The hydrothermal system was derived from an alkaline magma and the deposit is defined as an alkaline rock-hosted hydrothermal gold deposit.

The Taihua metamorphic complex exposes in the southern Trans-North China Orogen (TNCO) and records at least three episodes of magmatism. The Shanxian TTG gneisses obtained at 2.54–2.48 Ga have high SiO 2 , variable Mg# with high (La/Yb) N and Sr/Y ratios (15.08–93.26 with average of 37.31 and 7.33–115.05 with average of 49.59, respectively). They show negative Nb and Ta but positive Zr and Hf anomalies with low Nb/Ta and Gd/Yb, and high Zr/Hf and Zr/Sm ratios (4.97–18.8, 1.92–6.37, 23.71–50.26, and 29.18–75.23, respectively), and have positive e Hf (t) values (+1.7 to +7.9) and e Nd (t) values (+0.72 to +2.55), indicating that they were possibly produced by partial melting of lower crust derived from metasomatized lithospheric mantle with the residue of minor garnet. The Sihe granitic gneisses recorded at 2.35–2.30 Ga are enriched in silica, Al 2 O 3 contents (13.59–15.33), K 2 O/Na 2 O ratios (1.13–1.7), defined as high-Al TTG. They exhibit high Sr/Y, Zr/Sm and Zr/Hf ratios and low Nb/Ta and Gd/Yb ratios (44.71–83.09, 47.79–62.58, 36.05–37.43, 12.04–16.36, and 2.95–3.68, respectively) with negative Eu anomaly. Combined with Hf and Nd isotopes (−2.5 to +4.7 and −0.74 to +0.36), the Sihe granitic gneiss was possibly generated from partial melting of lower crust with minor ancient material contributions, leaving residual amphibole and minor garnet in the source. The Muce monzonitic gneisses emplaced at 2.17–2.16 Ga have high Mg#, Ni and Cr contents, constant Sr/Y and (La/Yb) N (42.39–50.33, 19.8–41.4, 33.6–74.2, 31.32–34.14, and 15.32–16.7, respectively), with relatively low and constant Dy/Yb ratio (1.82–1.85). Together with Hf and Nd isotopes (−6.5 to −0.9 and −2.07 to −2.86), the Muce monzonitic gneisses might be derived from partial melting of Neoarchean pre-existing crustal materials, possibly in an arc setting. It is therefore found that four episodes of crustal growth and/or reworking in the southern segment of the TNCO have occurred at 2.85–2.72 Ga, 2.57–2.48 Ga, 2.35–2.30 Ga and 2.2–2.0 Ga, respectively, likely to connect with the subduction–collision between the Eastern and Western Blocks along the TNCO in the North China Craton.

Sixty-six passive continental margin basins around the world were compared comprehensively from the aspect of seismogeology on the basis of plate tectonics. According to their textural and structural differences, passive continental margin basins were classified into seven subdivisions, i.e., rifted basin, non-saline faulted depression basin, saline faulted depression basin, non-saline depression basin, saline depression basin, delta reformed basin and positive reverse deformed basin. The passive continental margin basins around the world have been generated with the formation of Mesozoic and Cenozoic Atlantic and Indian Oceans and they have experienced superimposition of three prototypes, including intra-continental rift in rifting period, intercontinental rift in transitional period and passive continental margin in drifting period. In rifted basins, the petroleum systems are mainly located in the lower lacustrine/marine rift series of strata and the thinner depression series of strata at the upper part are only regional cap-rocks. Large oil and gas fields are mainly concentrated in structural traps of rift series of strata. In non-saline faulted depression basins, hydrocarbon generation and expulsion peaks occur in both upper thicker marine depression series of strata and lower rift series of strata. Reservoirs are formed in the structures of rift series of strata, and oil and gas are highly concentrated at slope fans in depression series of strata. In saline faulted depression basins, large oil and gas fields are mainly distributed in the lagoon carbonate rocks of subsalt series of strata and the deepwater slope fans of suprasalt depression series of strata. In saline depression basins, only petroleum systems in depression series of strata are active, and various traps are developed, such as slope fan, salt structure and bioherm. In non-saline depression basins, large oil and gas fields are mainly located in submarine fan groups of depression series of strata because this type of basins are of narrow continental shelf and steep continental slope. In delta reformed basins, four major ring-like structure belts (i.e., growth faulting-mud diapir-thrust nappe-foredeep gentle slope) are formed from the shore to the deepwater and large oil and gas fields can be formed in each belt. Positive reverse reformed basins are the passive continental margin basins which are influenced by global orogenesis since the Miocene. In this type of basins, oil and gas are concentrated in compressional anticlines of reverse series of strata. Key words: passive continental margin, prototype basin, basin structure, basin classification, large oil and gas field, distribution rules

Ultrafine powders of scandia-stabilized zirconia (ScSZ) were prepared by the co-precipitation method, using ZrOCl2 and ScO2 as raw materials and NH3·H2O as a precipitant. In this paper, the optimum process parameters were investigated. The pH of the reaction solution directly impacted the precursor structure, which further affected the obtained crystal forming. Many experiment methods of thermogravimetric analysis and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy (Raman), and nitrogen adsorption were employed to characterize the ScSZ powder. The structure transition mechanism from cubic to rhombohedral was discussed. In addition, the electrical conductivity of the powders was also studied after dry-pressing and calcining. The results showed that the structure of ScSZ with complete crystal surface belonged to the cubic phase. The crystallite sizes of the powders prepared are about 60-80 nm, meet the conditions of (D90-D10)/2D50≤1, and exhibited the good flow properties. The electrical conductivity was more than 190 mS/cm in air measured at 850 °C.

To understand how black carbon (BC) might affect the nature of polycyclic aromatic hydrocarbons (PAHs) diffusion at the water–sediment interface and how their diffusion process and ecological risks vary in different functional areas due to strong heterogeneity of urban system. 24 pairs of samples (water and sediment) were collected across the watery landscape of Wuhu, China in four functional areas. The results suggested that PAHs concentrations ranged between 6.95 and 43.2 ng/L, with a mean value of 19.8 ng/L in water, and were from 32.8 to 3790 ng/g averaging 690 ng/g in sediment. The primary sources of the PAHs might be coal combustion and biomass combustion as was revealed by Positive Matrix Factorization model. BC can absorb PAHs, especially high-molecular-weight (HMW) PAHs with strong lipophilic properties, into sediment and affect their diffusion trend at water-sediment interface in different functional areas. The coexistence of BC and PAHs will affect the associated risks in aquatic environments. The water has a higher risk in the education and residential area, which was polluted by low-molecular-weight (LMW) PAHs. The sediment risk was mainly manifested in industrial areas, which are contaminated by HMW PAHs that was caused by the presence of BC. These results indicate that it is very significant for ecological risk assessment to understand the pollution status of PAHs in different functional areas and their relationship with BC.

As a key accessory mineral in metapelite, monazite forms in the metamorphic event and therefore, places important direct constraint on the timing of the tectono-metamorphic event. In this study, we investigate four representative metapelites from different metamorphic terranes in the central-south Trans-North China Orogen (TNCO), applying secondary ion mass spectrometry (SIMS) U–Th–Pb dating on monazite. The dating results reveal that monazite collected from the Huashan, Luoning, Zanhuang and Wutai metamorphic complexes record the metamorphic ages of ~1.83 Ga, ~1.95 Ga, ~1.85 Ga and ~1.91 to 1.83 Ga, respectively. Combined with the literature data of metamorphic geochronology on the discrete terranes within the TNCO, it is suggested that the amalgamation between the Western and Eastern Blocks of the North China Craton along the nearly NS-trending TNCO stared as earlier as ~1.97 Ga and continued to as late as ~1.80 Ga, which was in fact a long-lived tectono-metamorphic event.

Garnet-bearing amphibolites and metapelites of the Luoning metamorphic terrane, Taihua metamorphic complex, southern terminal of the Palaeoproterozoic Trans-North China Orogen (TNCO), preserve different metamorphic mineral assemblages formed at three metamorphic stages in the Palaeoproterozoic. The prograde mineral assemblages (M1) comprise of hornblende + plagioclase + quartz ± biotite inclusions preserved in the garnet porphyroblasts in the amphibolites or quartz + biotite + plagioclase inclusions preserved in the garnet porphyroblasts in the metapelites. The metamorphic peak mineral assemblages (M2) are represented by the garnet porphyroblasts as well as the matrix minerals plagioclase + hornblende ± biotite + quartz in the amphibolites or quartz + biotite + plagioclase ± hornblende in the metapelites, respectively. The retrograde mineral assemblages (M3) are the worm-like, fine-grained “white-eye socket” symplectitic assemblages formed between the relict garnet porphyroblasts and the matrix minerals, consisting of plagioclase + hornblende ± biotite intergrowths in the amphibolites or plagioclase + biotite + quartz intergrowths in the metapelites, respectively. Geothermobarometric computation shows that the Luoning terrane records clockwise P – T trajectories including near isothermal decompression (ITD) processes, from 630–790 °C/5.3–8.9 kbar through 720–820 °C/8.9–10.7 kbar to 690–740 °C/7.1–7.7 kbar. SIMS U–Pb dating of zircons separated from the amphibolites and metapelites presents that the age of the protolith of the amphibolites is ∼2.32 Ga and the metamorphism occurred during 1.97–1.94 Ga, suggesting that the subduction–collision and the subsequent exhumation occurred in the late Palaeoproterozoic. Combined with the literature data of the different discrete terranes within the Trans-North China Orogen, it is further deciphered that the tectono-metamorphic event of the Trans-North China Orogen started as early as 1.97 Ga and lasted as late as 1.80 Ga, suggesting that the tectono-metamorphic event of the orogen is a long and complex history.

Scandia stabilized zirconia powder (ScSZ) was first synthesized by a microwave-hydrothermal method. The crystalline and aggregated particle sizes were investigated by means of X-ray diffraction (XRD), Raman, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Weakly agglomerated and well crystallized ScSZ powder was prepared by microwave-heating to 150 °C and 2.5 h. The structure of the ScSZ powder changed from a tetragonal to a cubic phase, and accordingly, the powder conductivity was increased from 90.55 to 120.56 ms/cm by the introduction of the mineralizer solutions (KOH+K 2 CO 3 ) during the microwave-hydrothermal processing.

The Dongping gold deposit is a mesothermal lode gold deposit hosted in syenite. The ore petrography and chemistry of the tellurides from the alteration zone of the deposit have been studied in detail using optical microscopy, scanning electron microscopy, electron probe micro-beam and X-ray diffraction facilities. The tellurides, consisting mostly of calaverite, altaite, petzite tellurobismuthite and tetradymite, are hosted irregularly in pyrite fractures and voids. In the ore bodies, the species and quantity of tellurides decrease from the top downwards, accompanied with lowering of gold fineness, and the existence of tellurides exhibits a positive correlation with gold enrichment. Mineral paragenesis and chemical variations suggest that during evolution of the ore-forming fluids Te preferably incorporated with Pb to form altaite, followed in sequence by precipitation of petzite, and calaverite when Ag has been exhausted, and the residue fluids were enriched in Au, giving rise to formation of native gold. Calculation with reference of the fineness of native gold coexisting with the tellurides indicates that at 300 °C, log f (Te 2 ) varied between − 8.650 and − 7.625. Taking account of the Au–Ag–Te mineral paragenesis, it is inferred that log ƒ (Te 2 ) varies from − 9.12 to − 6.43, log ƒ (S 2 ) − 11.47 to − 8.86. In consideration of the physicochemical conditions for formation of tellurides, with comparison to some known telluride deposits, it is suggested that high log ƒ (Te 2 ) is a key factor for high fineness of native gold as well as precipitation of abundant tellurides.

The Ti-in-muscovite geothermometer was empirically calibrated as ln[T(oC)] = 7.258 + 0.289 ln(Ti) + 0.158[Mg/(Fe + Mg)] + 0.031 ln[P(kbar)] using ilmenite- and Al2SiO5-bearing assemblages in metapelites under P–T conditions of 450–800 °C and 0.1–1.4 GPa. The calibration was conducted for muscovites containing Ti = 0.01–0.07, Fe = 0.03–0.16, Mg = 0.01–0.32 and Mg/(Fe + Mg) = 0.05–0.73, respectively, on the basis of 11 oxygen per formula unit. Such compositional range covers more than 90% natural muscovites, and the random error of this thermometer is estimated to be of ± 65 °C. The geothermometer was validated against a set of independently determined temperature conditions between different degrees in samples from different prograde, inverted and contact metamorphic terranes. Application of this thermometer beyond the calibration conditions is not encouraged.

At Qianliyan Island, about 80 km East of Qingdao in the northern part of the South Yellow Sea of China, lenses and layers of eclogite and two-mica epidote–plagioclase gneiss occur within granitic gneiss. From the eclogite, peak metamorphic conditions of 775°C, 2.6 GPa were defined using compositions of garnet mantle zones, omphacite inclusions, and homogeneous phengite cores with high Si contents. During exhumation, the eclogite underwent different stages of retrogression, i.e . at amphibolite-facies (740–790°C, 1.60–1.75 GPa,), epidote-amphibolite-facies (640–690°C, 0.8–1.0 GPa), and, finally, at greenschist-facies conditions. Relics of omphacite and garnet in pyrite of the two-mica epidote–plagioclase gneiss, although obliterated in the rock matrix, prove this rock also to have experienced high-pressure (HP) metamorphic conditions. Similar HP metamorphic rocks occur at Sulu and Dabie in the west and at the Hongseong complex of South Korea in the east, enhancing the probability of a coherent HP/(UHP) belt ranging from Qinlin in the west towards the Korean peninsula in the east.

Exposed in the southernmost terminal of the Palaeoproterozoic Trans-North China Orogen (TNCO), the garnet-bearing amphibolites in the Mts. Huashan metamorphic complex preserve three generations of mineral assemblages including the prograde, peak and retrograde metamorphic stages. The prograde metamorphic stage (M1) is recognized as inclusion-type mineral assemblages (hornblende + plagioclase + quartz ± biotite ± ilmenite) preserved in the garnet porphyroblasts. The peak metamorphic assemblages (M2) are represented by the garnet porphyroblasts and matrix minerals (hornblende + plagioclase + quartz ± biotite ± ilmenite). The retrograde metamorphic assemblages (M3) are characterized by the symplectitic intergrowth minerals (hornblende + plagioclase + quartz ± orthopyroxene ± biotite ± ilmenite) rimming decomposed, relict garnet porphyroblasts, known as the “white-eye socket” reaction textures. Calculated by geothermometers and geobarometers, the P–T conditions of these three metamorphic stages are estimated to be of 5.7–6.0 kbar/660–760 °C for the prograde stage (M1), 6.6–7.7 kbar/700–820 °C for the peak stage (M2) and 4.5–6.7 kbar/720–760 °C for the retrograde stage (M3), respectively. Therefore, these three metamorphic stages define clockwise P–T paths including nearly isothermal decompression (ITD) processes. Geochronological studies of zircons from the amphibolites indicate that the protolith of the amphibolites formed at ∼2.3 Ga, and the metamorphism occurred at ∼1.87–1.85 Ga, and the metamorphic period was further deciphered to be of 1.96–1.80 Ga when considering our previous reports. It is therefore proposed that the southernmost terminal of the TNCO was also involved in the subduction and collision processes between the Eastern and Western Blocks of the North China Craton at least as early as 1.96 Ga and continued as late as 1.80 Ga, followed by rapid uplift and exhumation. The available data suggest that the Palaeoproterozoic tectono-metamorphic event of the southernmost terminal of the Trans-North China Orogen not only started earlier but also continued longer than the other terranes in the middle and northern sections elsewhere in the orogen.

The effect of injection pressure, piston velocity, and the forming temperature of semisolid slurry on the filling behavior of the semi-solid A356 aluminum alloy was investigated by simulation methods. The simulation results show that these processing parameters have an important effect on the filling behavior of the semi-solid A356 aluminum alloy. The slurry flows steadily in the cavity when the injection pressure, the piston velocity, and the forming temperature are low, but it is prone to turbulent flow when the injection pressure, the piston velocity, and the forming temperature are much higher. Therefore it is necessary to determine the appropriate processing parameters to get a steady flow of the slurry in the cavity.

An apparent viscosity model of semi-solid A356 aluminum alloy has been developed and the software Castsoft6.0 coupled with the model has been used to simulate the mould filling of an automobile master brake cylinder with the semi-solid A356 alumi-num alloy slurry. The simulation results are in agreement with the practical filling process, indicating that the apparent viscosity model is feasible and can be used to simulate the mould filling of the semisolid A356 aluminum alloy slurry and can be used to optimize the filling process and the design of dies. A higher injection pressure, a higher ingate flow velocity of the semi-solid slurry, and a higher slurry temperature are advantageous to the mould filling of the automobile master brake cylinder.

Signatures of the North Atlantic Oscillation (NAO) are widely detected in climatic variability, particularly in the extratropical latitudes surrounding the North Atlantic Ocean. However, it is still controversial whether the NAO is the most important pattern of nonseasonal variability of atmospheric circulation related to precipitation over Europe. This paper is an attempt to contribute to this issue. The spatial modes of nonseasonal variability of monthly fields of mean sea level pressure (MSLP) over the northeastern Atlantic and western Europe and precipitation over Europe are investigated mainly by using principal component analysis. The relationships between the two fields are studied via canonical correlation analysis (CCA). The data sets used refer to the period from 1911 to 1990. The most important spatial mode of MSLP is the NAO pattern, its corresponding principal component being closely related to the NAO index. Interestingly however, the NAO pattern seems to be responsible only for the second empirical orthogonal function in precipitation, while the most important spatial mode of precipitation corresponds to the third EOF of MSLP (North Sea pattern). Furthermore, the second EOF of MSLP (Scandinavian pattern) is highly associated with the third EOF of precipitation. Significant pairs of canonical patterns between the MSLP and precipitation fields obtained from canonical correlation analysis are coherent with the conclusions above. These results can potentially be used to assess possible changes of precipitation over Europe due to increasing greenhouse gases based on the variability of MSLP simulated by general circulation models.

[1] Changes of vegetation phenology in response to climate change in the temperate forests have been well documented recently and have important implications on the regional and global carbon and water cycles. Predicting the impact of changing phenology on terrestrial ecosystems requires an accurate phenology model. Although species-level phenology models have been tested using a small number of vegetation species, they are rarely examined at the regional level. In this study, we used remotely sensed phenology and meteorological data to parameterize the species-level phenology models. We used a remotely sensed vegetation index (Two-band Enhanced Vegetation Index, EVI2) derived from the Moderate Resolution Spectroradiometer (MODIS) 8-day reflectance product from 2000 to 2010 of New England, United States to calculate remotely sensed vegetation phenology (start/end of season, or SOS/EOS). The SOS/EOS and the daily mean air temperature data from weather stations were used to parameterize three budburst models and one senescence model. We compared the relative strengths of the models to predict vegetation phenology and selected the best model to reconstruct the “landscape phenology” in New England from year 1960 to 2010. Of the three budburst models tested, the spring warming model showed the best performance with an averaged Root Mean Square Deviation (RMSD) of 4.59 days. The Akaike Information Criterion supported the spring warming model in all the weather stations. For senescence modeling, the Delpierre model was better than a null model (the averaged phenology of each weather station, averaged model efficiency = 0.33) and has a RMSD of 8.05 days. A retrospective analysis using the spring warming model suggests a statistically significant advance of SOS in New England from 1960 to 2010 averaged as 0.143 days per year (p = 0.015). EOS calculated using the Delpierre model and growing season length showed no statistically significant advance or delay between 1960 and 2010 in this region. These results suggest the applicability of species-level phenology models at the regional level (and potentially terrestrial biosphere models) and the feasibility of using these models in reconstructing and predicting vegetation phenology.

Garnetiferous amphibolites preserving prograde inclusion assemblages (M1) within garnet porphyroblasts, metamorphic peak assemblages (M2) and post-peak symplectitic assemblages (M3) have been found in the Lushan terrane, Henan Province, Taihua Metamorphic Complex, southernmost section of the NS-striking Palaeoproterozoic Trans-North China Orogen (TNCO). Geothermobarometric computation shows that the M1, M2 and M3 assemblages were formed under the P–T conditions of 650–730 °C/4.9–8.1 kbar, 740–810 °C/9–10.8 kbar and 750–760 °C/5.0–7.7 kbar, respectively, suggesting that these amphibolites record clockwise P–T paths including nearly isothermal decompression (ITD) segments similar to the west-Alpine type P–T paths, indicative of being resulted from an orogenic process. High resolution SIMS U–Pb dating of metamorphic zircons suggests that the metamorphism took place at ca. 1.95–1.75 Ga. These data imply that the Palaeoproterozoic collision between the Eastern and Western Blocks of the North China Craton along the southernmost terminal of the TNCO not only started earlier, but also continued longer, than the middle and north sections of the TNCO.