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The Laowan super-large (208 t Au) gold deposit is located in the Tongbai orogenic belt, along with a newly-discovered molybdenite deposit at its depth in the northern periphery. The gold deposit is a fault-controlled lode gold deposit featuring sulfide quartz vein-type and altered rock-type mineralization hosted within the metamorphic rocks, whereas the molybdenum deposit is a typical porphyry-type deposit. These two deposits have their respective paragenetic sequences and mineralization types without spatial overlapping in the ore field. Here, we present U–Pb dating of zircon, hydrothermal rutile, and REE phosphates, and Re–Os dating of molybdenite to constrain the relationship between the Au and Mo mineralization, and their relation to Mesozoic granitic magmatism. Textural features indicate that rutiles and associated phosphate minerals are of hydrothermal origin, generated by re-precipitation and dissolution of titanite crystals hosted in the metamorphic host rocks due to hydrothermal alteration during Au and Mo mineralization. LA-ICP-MS U–Pb dating of rutile from the auriferous altered rocks yields a 206Pb/238U age of 120.0 ± 6.7 Ma (MSWD = 1.4), consistent with the ages of the associated monazite (125.0 ± 2.4 Ma) and xenotime (126.3 ± 2.0 Ma), representing the timing of the gold mineralization, coeval with Laowan monzogranite (zircon U–Pb: 128.8 ± 0.7 Ma). Rutile from the molybdenum deposit show an older 206Pb/238U age of 141.0 ± 11 Ma (MSWD = 1.1), consistent with the molybdenite Re–Os age (141.5 ± 1.7 Ma; MSWD = 0.27) and the zircon U-Pb age (141.6 ± 0.8 Ma; MSWD = 1.5) of the Songpa porphyry. Hence, the Au and Mo mineralization in the Laowan district represent two episodic mineralization events related to the late Mesozoic granitic magmatism. Our study also suggested that multiple isotopic dating is helpful to precisely constraint the ages for complex hydrothermal deposits.

The large Hebaoshan gold deposit (41.5 t Au, average grade: 3.5 g/t) is located in a hitherto poorly documented gold province in the northeastern part of the South China Block. It is hosted by Precambrian metasedimentary rocks that experienced Triassic greenschist- to amphibolite-facies metamorphism. Three hydrothermal stages can be distinguished: quartz + sericite + pyrite + pyrrhotite (stage I), quartz + magnetite + sulfide (stage II), and quartz + carbonate + pyrite + hematite (stage III). Auriferous pyrite samples yielded a Rb-Sr isochron age of 234 ± 3 Ma (2σ, MSWD = 0.24), and ore-related hydrothermal sericite yielded a 40Ar-39Ar plateau age of 226.4 ± 2.0 Ma (2σ, MSWD = 1.01), which are distinctly younger than ca. 430 Ma granitic rocks in the mining district and older than 170–130 Ma granites in the region, ruling out any genetic link between granite emplacement and gold mineralization. The mineralizing fluid system can be described as carbonic-aqueous with low to moderate salinity (2.2–10.1 wt% NaCl equiv.) and medium temperature of 290 to 350 °C (stage I) and 230 to 280 °C (stage II). The δ18O quartz ranges from 13.3 to 15.4 ‰, and the δD values for fluid inclusions in quartz range from − 97 to − 60 ‰. The calcite has C-isotopes ranging from − 6.1 to − 3.8 ‰ and O-isotopes from 2.8 to 13.6 ‰. H-O-C isotope data are consistent with a metamorphic fluid derived from devolatilization of Neoproterozoic basement rocks during regional metamorphism in the Late Triassic Indosinian period. The δ34S values of sulfides for stages I, II, and III are 0.1 to 7.8 ‰, − 10.6 to 5.1 ‰, and − 18.9 to − 14.1 ‰, respectively, indicating an increase in oxygen fugacity during fluid ascent which resulted in more negative sulfur isotope values of sulfides and precipitation of gold. Pyrite separates have 206Pb/204Pb ratios of 17.340 to 17.687, 207Pb/204Pb ratios of 15.539 to 15.604, and 208Pb/204Pb ratios of 37.749 to 38.094. The S-Pb isotope data suggest derivation of S and Pb from the Precambrian metasedimentary country rocks. Auriferous pyrite yielded elevated 3He/4He ratios (0.78–1.46 Ra), which suggest a mantle component as can be expected from fluids derived from a subduction setting. It is concluded that Hebaoshan is an orogenic gold deposit that formed during Triassic flat-slab subduction of the paleo-Pacific plate beneath the South China Block and thus constitutes the first Triassic deposit of this type recognized in the coastal area of Southeast China.

The Shuangqishan gold deposit (>20t gold) is located in a hitherto poorly-documented gold province in the southeastern Cathaysia Block, South China. It is hosted by Neoproterozoic amphibolite-facies metamorphic rocks and consists of quartz-sulfide veins with distinct alteration haloes. Three stages of hydrothermal activity have been identified, and gold is mainly associated with veins of Stage II (quartz-pyrite±chalcopyrite). Gold occurs both as refractory gold hosted by pyrite and free gold enclosed in, or filling, microfractures of pyrite and quartz. U-Pb isotope dating of hydrothermal apatite from the Substage IIa veins yielded an age of 436.8 ± 7.6 Ma. The ore fluid was of carbonic-aqueous composition and low oxygen fugacity. Total homogenization temperatures in Substage IIa and IIb range from 270° to 310°C and 250° to 295°C, respectively. Variable CO2/H2O ratios indicate fluid unmixing under fluctuating pressures. Stage I quartz veins show evidence of ductile deformation and have δ18Ofluid and δD values of 10.3 to 11.2‰ and −67to −66‰, respectively, consistent with a metamorphic fluid. Stage II veins have slightly higher δ18O values of 10.9 to 13.7‰, with calculated δ18Ofluid values of 4.8 to 8.0‰. The 3He/4He ratios of pyrite are elevated (0.06–0.23 Ra) relative to crustal He reservoirs (

Several Late Devonian sedimentary successions host pyrite with highly positive sulfur isotope values (δ34Spyrite). These anomalous values have been linked to marine anoxia, low sulfate concentrations in seawater, or aerobic re-oxidation of dissolved sulfide within well-oxygenated bottom waters in a local depositional environment. Implicit to these previous models is the assumption of a biogenic genesis from microbial sulfate reduction (MSR) of these pyrites, which, in turn, can be used to understand the biogeochemical sulfur cycle and reconstruct paleoenvironmental conditions. In South China, the Late-Devonian bulk-rock sulfur isotope excursion occurs in the lower Fammenian Wuzhishan Formation of the Youjiang Basin, in both the sedimentary limestone that corresponds to the Late triangularis conodont zone at the Fuhe section and the sediment-hosted Xialei Mn deposit that lies between the Late triangularis and crepida conodont zones. To further constrain the significance of these 34S-enriched pyrites, we carried out detailed textural and in-situ sulfur isotope examinations of pyrites in the Xialei Mn deposit. We found one type of pyrite in siliceous limestone referred to as the host rocks and three distinct pyrite types in Mn ores: Type I – pyrites with Mn-carbonate inclusion-rich cores; Type II – pyrite overgrowths surrounding an “inclusion-rich” core; and Type III – relatively inclusion-poor and mainly subhedral disseminated pyrite grains. Type I pyrites in Mn ores have negative δ34Spyrite values from −7.8‰ to −2.0‰. Types II and III pyrites, and pyrites in the host rock are characterized by highly positive δ34Spyrite values (+4.2‰ to +37.6‰), with some values being higher than that of contemporaneous seawater sulfate. Type I pyrites with negative δ34S values likely formed via MSR in a closed porewater system, driven by increased sedimentation rates during a sea level lowstand. The other pyrites with highly positive δ34S values appear to have formed during secondary hydrothermal alteration, with their sulfur sourced through thermochemical sulfate reduction (TSR) of sulfate from dissolved barites in the underlying Liujiang Formation. This implies that the positive δ34S values of the Late Devonian pyrites from the Wuzhishan Formation represent a later alteration event caused by post-depositional hydrothermal fluids, and may lack a direct biogeochemical connection to the surface sulfur cycle. These results provide an important perspective on the origin of variability in sulfur isotope records and suggest the need for careful petrographic screening and micrometer-scale analysis of sedimentary units used to reconstruct paleoenvironmental conditions.

Unlike classic skarn-type scheelite deposits directly acquiring sufficient Ca2+ from surrounding limestones, all of the scheelite orebodies of the Shangfang tungsten (W) deposit occur mainly in amphibolite, and this provides a new perspective on the mineralization mechanism of W deposits. The ability of hydrothermal scheelite (CaWO4) to bind REE3+ in their Ca2+ crystal lattices makes it a useful mineral for tracing fluid-rock interactions in hydrothermal mineralization systems. In this study, the REE compositions of scheelite and some silicate minerals were measured systematically in-situ by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to assess the extent of fluid-rock interactions for the Late Mesozoic quartz-vein-type Shangfang W deposits. According to the variations in CaO and REE among scheelite and silicate minerals, the amphibole and actinolite in amphibolite may be able to release large amounts of Ca2+ and REE3+ into the ore-forming fluids during chlorite alteration, which is critical for scheelite precipitation. Furthermore, an improved batch crystallization model was adopted for simulating the process of scheelite precipitation and fluid evolution. The results of both the in-situ measurements and model calculations demonstrate that the precipitation of early-stage scheelite with medium rare-earth elements (MREE)-rich and [Eu/Eu*]N 1. Even though the partition coefficient of REE is constant, the later-stage scheelite will also inherit a certain degree of MREE-depletion and [Eu/Eu*]N future from the residual fluids. As a common mineral, sheelite forms in various types of hydrothermal ore deposits (e.g., tungsten and gold deposits). Hence, the improved batch crystallization model is also possible for obtaining detailed information regarding fluid evolution for other types of hydrothermal deposits. The results from model calculations also illustrate that the Eu anomalies of scheelite are not an effective index correlated to oxygen fugacity of fluids but rather are dominantly controlled by the continuous precipitation of scheelite.

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

The southern Myanmar tin ore district is an important part of the well-known Southeast Asia tin belt (SATB), and hosts numerous economically important primary tin-tungsten ore deposits. However, the timing of formation of these deposits is unclear due to the scarcity of robust age data. The tectonic setting of tin mineralization in this area also needs to be further constrained. Most of the primary tin-tungsten ore deposits in southern Myanmar are typical hydrothermal quartz vein–type, with cassiterite and wolframite as the main ore minerals. Here, we present in situ U–Pb ages of cassiterite and wolframite from nine granite-related hydrothermal Sn–W deposits in southern Myanmar. Cassiterite samples from the Hermyingyi, Thitkhatoe, Thaling Taung, Kalonta, Taungphila, Pagaye, Bawapin, Kanbauk, and Letha Taung deposits yield common lead-corrected weighted mean 206Pb/ 238U ages of 61.6 ± 0.8 Ma, 61.9 ± 0.6 Ma, 60.4 ± 0.9 Ma, 63.0 ± 0.6 Ma, 62.9 ± 0.6 Ma, 69.5 ± 0.5 Ma, 63.6 ± 0.6 Ma, 61.3 ± 0.6 Ma, and 84.9 ± 0.5 Ma, respectively. Wolframite samples collected from these deposits also yield consistent ages with the cassiterite samples. These ages, combined with available tin mineralization ages from other deposits in the western part of the SATB, define three epochs of Sn metallogeny related to three contrasting geodynamic settings: (1) Early Cretaceous (~ 125–110 Ma) mineralization is related to post-collision slab break-off after collision between the West Burma terrane and the Sibumasu-Tengchong terrane; (2) Late Cretaceous to Paleocene (~ 90–60 Ma) mineralization developed in an Andean-type accretionary setting during subduction of the Neo-Tethys oceanic lithosphere; (3) Early Eocene (~ 50–40 Ma) mineralization may have formed in a post-collision setting after the India-Asia collision.

Gypsum often occurs in marine sediments as an authigenic mineral, but it may also be produced artificially through oxidation of sulfide during sample storage and preparation. Therefore, the origin of the gypsum should be carefully checked, especially for those DSDP, ODP and IODP samples that have stored for a long time. It is nearly impossible to distinguish between gypsum formed by these two processes based on the mineral morphology or the sulfur and oxygen isotope methods currently used. In this study, we proposed a simple, quantitative scheme based on chemical extractions of iron and sulfur to distinguish whether the gypsum in marine sediment samples is an authigenic mineral or an artificial product formed after sample collection. The new method was tested on two suites of deep-water sediment cores sampled from Hydrate Ridge and Kaoping Slope, in which the origins of gypsum were known beforehand, and was successfully validated. Finally, the potential influence of artificial productions of elemental sulfur and jarosite on the application of this new method was evaluated and the corresponding solutions were given.

The large-scale, high-grade Sn ores and the Cu-Sn metal association in the volcanic massive sulfide (VMS) ores in Neves Corvo are unique among VMS deposits, not only in the Iberian Pyrite Belt but also worldwide. Thus, the exceptional nature of the Neves Corvo deposit calls for unusual metallogenic processes. Previous efforts to constrain these processes have been hampered by a lack of high precision ages for the mineralization. This has led to a debate as to whether tin mineralization occurred at the same time as the associated volcanism and VMS-style mineralization, or is the result of later processes events associated with the Hercynian orogeny. We report in-situ U-Pb dating results of hydrothermal cassiterite and sulfur isotopic compositions of sulfides in the Neves Corvo deposit that place tight constraints on the timing of mineralization and on the origin of the hydrothermal ore-forming fluids. The cassiterite samples yield U-Pb ages of the Sn mineralization of 363–366 Ma; identical to the age of the host volcanic rocks. δ34S values range from −32.3‰ to +17.4‰ among the different VMS ore types and are largely consistent with microbiological reduction of seawater sulfate, but with some positive values resulting from thermochemical sulfate reduction. In contrast, the Sn-rich ores have a limited range in δ34S that clusters near 0‰, which suggests derivation from magmatic fluids. Hence, the unusually high Sn grades at the Neves Corvo deposit are interpreted to be derived from fluids exsolved from a hidden granitic source essentially synchronous with formation of the volcanic rocks and VMS mineralization.

The Qiyugou district is one of the most important gold deposit distribution areas in the Xiong’ershan region, North China Craton. These deposits are hosted in Archean Taihua Supergroup rocks as gold-bearing breccia pipes. Here, we report a detailed in situ analysis of trace elements and S-Pb isotopes in sulfides from different ore stages, in combination with electron probe microanalysis of ore minerals from the gold-bearing J4 breccia pipe in the Qiyugou district, to unravel the gold distribution and their textural relationships to pyrite, the metal sources and S-Pb isotopic composition variations during the ore-forming processes. The Qiyugou breccia pipes hosted gold ore (over 70 t Au, average grade of 2–5 g/t) that formed in four mineralization stages, i.e., an early K-feldspar-biotite-magnetite-quartz-pyrite (Py-1) stage (I) that can be further divided into two substages, namely the Ia K-feldspar-biotite-magnetite stage and the Ib quartz-pyrite stage; a gold-pyrite (Py-2)-quartz stage (II); a gold-quartz-polymetallic sulfide (Py-3) stage (III); and a late quartz-carbonate stage (IV). The visible native gold and electrum grains occur as small inclusions and disseminations in the fractures within Py-2 and Py-3. Tellurides and Bi-Pb-minerals are widespread in the stage II stockworks and veins, as is intergrowth with visible native gold and Py-2. In situ LA-ICP-MS trace element analysis reveals the presence of invisible gold hosted in three types of pyrite with extremely low Au content (Py-1 ≤ 0.05 ppm; Py-2 ≤ 0.03 ppm; Py-3 ≤ 0.02 ppm). Concentrations of Te, Bi, and Pb in pyrite are high and correlate well with Au concentrations, but As content is low. Therefore, the Te, Bi and Pb played a significant role in gold mineralization in As-deficient ore fluids in the J4 gold-bearing breccia pipe from the Qiyugou district. High-precision in situ laser ablation multiple collector inductively coupled mass spectrometry (LA-MC-ICP-MS) lead isotope analyses indicate that the sulfides have 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios from 17.250 to 17.629, from 15.401 to 15.621, and from 37.649 to 38.290, respectively, which are similar to the granite porphyry in the district and indicative of their similar lead sources. High-precision in situ LA-MC-ICP-MS sulfur isotope analyses of pyrite show a large δ34S variation (e.g., from −18.1 to −11.1 per mil for Py-1, from −12.2 to − 6.6 per mil for Py-2, and from −4.9 to −1.6 per mil for Py-3) with a remarkable increasing trend from stage I, stage IIto stage III. This trend may record a decreasing oxygen fugacity of the ore-forming fluids during mineralization.

Abundant tourmaline occurs in Late Triassic biotite-muscovite granites of Mashhad (NE Iran), with several distinct morphologies including tourmaline nodules in granite, pegmatitic tourmalines, aplitic tourmalines, and vein-related tourmalines (quartz-tourmaline vein, tourmaline-rich vein and radial tourmalines). Pegmatitic and aplitic tourmalines are compositionally Fe-rich schorl and the nodule, radial and vein tourmalines are Mg-rich schorl. The tourmalines have generally low abundances for most trace elements except for Sr, Ga, Li, Be, Sn, Pb and some transition elements. Tourmalines have low REE abundances and are enriched in LREE and depleted in HREE (mostly below detection limits) with positive Eu anomalies. The concentration of several trace elements (e.g., Pb, Be, Sn, Ga, Sr, Pb, and REE) correlates well with the major element composition of the tourmalines (e.g. Mg# (Mg/Mg + Fe), vacancy/)X-site vacancy + Na(and Na/)Na + Ca. Trace element data of coexisting minerals with tourmaline indicate that the oligoclase and albite show the most preference in Sr, Pb and Eu and LREEs, biotite readily incorporates Rb, Ba, Zn, Li, Cs and Nb; K-feldspar has high contents of Rb, Ba, Sr and Pb; and garnet incorporates HREEs and Y during magma differentiation. The B-O-H isotopic compositions for all tourmalines are consistent with an S-type granite source, that was derived from partial melting of the continental crust. The pegmatitic and aplitic tourmalines with Fe-rich schorl composition indicate magmatic conditions and the radial, vein, and nodule tourmalines with Mg-rich schorl composition formed during the transition from magmatic to hydrothermal conditions due to the internal evolution of the granitic magma.

The Zhaiping Ag-Pb-Zn deposit (204 t Ag, average grade: 221.8 g/t) is located in the coastal area of the Cathaysia Block, Southeast China. Vein-type Ag-Pb-Zn orebodies are mainly hosted in the early Cretaceous volcanic and subvolcanic rocks, and structurally controlled by a group of NW-trending extensional faults. Ore-related hydrothermal alteration is well developed on both sides of the veins, dominated by silicic, phyllic, propylitic, and carbonate alteration. Mineralization can be divided into three stages: (1) the pre-ore quartz-pyrite stage, (2) syn-ore quartz-Ag-base metal stage, and (3) post-ore quartz-calcite stage. Microthermometric measurements of fluid inclusion assemblages in quartz, fluorite, sphalerite, and calcite from various hydrothermal stages reveal that from the pre-ore, syn-ore to post-ore stages, the homogenization temperatures range from 365 to 319 °C, from 317 to 222 °C, and from 233 to 172 °C, respectively. Fluid salinities range from 1.7 to 10.8 wt% NaCl equivalent. The microthermometric data indicate that the fluid cooling and fluid-rock interaction are two important mechanisms for ore precipitation. The δ34SV-CDT values of sulfide minerals (pyrite, sphalerite, galena, pyrrhotite and tetrahedrite) range from −1.9 to 6.2‰, and mostly between 1.0 and 4.5‰, consistent with a deep-seated magmatic sulfur source. Hydrogen and oxygen isotopic compositions of quartz indicate a primarily magmatic origin for the ore-forming fluids, and the proportion of meteoric water increased during the ore-forming processes. Post-ore stage calcite has δ13CV-PDB values of −2.8 to −0.8‰ and δ18OV-SMOW values of 4.2–6.4‰, corresponding to calculated values of fluids of −3.2 to −1.1‰, and −4.9 to −2.8‰, respectively. The carbon isotopes indicate a magmatic source for carbon but the oxygen isotopes indicate a significant contribution of meteoric water during calcite precipitation. We therefore proposed that the Zhaiping deposit is a typical mesothermal deposit that formed in an extensional environment related to the early Cretaceous subduction of the paleo-Pacific plate.

The high mobility of boron during fluid-rock interaction makes it an effective tracer for the sources of magmatic and metamorphic fluids, as recorded in minerals such as tourmaline and muscovite. Although advances have been made in quantifying the fractionation of boron isotopes among different phases, boron isotope fractionation in complex silicate melts remains poorly understood. Here, we propose appropriate models for the BO 3 and BO 4 units in silicate melts covering a wide range of chemical compositions and boron coordination structures in silicate magmas, and report the results of a theoretical investigation of boron isotope fractionation among silicate melt, minerals and fluids using a first principles theoretical approach. A comparison of measured and calculated α factors in mineral-melt and fluid-melt systems shows good agreement, suggesting the applicability of a simplified treatment of boron coordination structures in silicate melt. The results of this study show that the proportion of trigonal/tetrahedral coordinated boron and the B/Si ordering in silicate tetrahedral layers control the boron isotope fractionation among different phases, and that the effect of chemical composition is minor (less than 2‰ at 600 K). The temperature-dependent boron isotope fractionations are described as 1000lnα mica-basic fluid = 0.8–2.4 × (1000/T) - 0.8 × (1000/T) 2, 1000lnα mica-acidic fluid = 7.0–14.0 × (1000/T) - 1.2 × (1000/T) 2 and 1000lnα mica-tur = 1.9–5.4 × (1000/T) -3.4 × (1000/T) 2 (T is temperature in Kelvins). At magmatic temperatures, ∆ 11B values between mineral/fluid and melt also vary with the proportion of the BO 4 unit in the melt. This study underpins the applicability of the white mica-tourmaline geothermometers and boron isotopes for fluid source identification, and also offers an explanation of boron isotope fractionation in systems that contain complex silicate melts.

Qinzhou-Hangzhou metallogenic belt is an important polymetallic (Cu, Mo, W, Sn, Pb, Zn, Au, and Ag) belt in South China. The Xinmin polymetallic deposit is located in the southwestern segment of this belt, which ore bodies hosted in the contact zone of granite and Lower Devonian sedimentary strata and in the structure fractured zone within the strata. Three hydrothermal stages can be distinguished: quartz+tourmaline+pyrite (early stage), tourmaline+pyrite+galena+bismuthinite+sphalerite+chalcopyrite+pyrrhotite (main stage), and quartz+calcite+dolomite (late stage). The mineralizing fluid system can be described as aqueous with medium-high salinity (2.7-50.7 wt.‰ NaCl equiv. in the main stage and 0.18-8.81 wt.‰ NaCl equiv. in the late stage) and medium-high temperature of 485°C to 205°C (main stage) and 300°C to 116°C (late stage). The trapping pressures varied from 2 MPa to 30 MPa (main stage) and 0.4 MPa to 9 MPa (late stage). The δ 18 O values of quartz range from 6.7‰ to 8.5‰, and the δ D values for fluid inclusions in quartz range from -45‰ to -52‰. The calcite has C-isotopes ranging from -5.8‰ to +0.7‰ and O-isotopes from +12.7‰ to 21.4‰. H-O-C isotope data are consistent with a hydrothermal fluid derived from the Cretaceous granitoid magma. The δ 34 S values of sulfides are -3.3‰ to +1.9‰. Sulfides have 206Pb/204Pb ratios of 18.377 to 18.473, 207Pb/204Pb ratios of 15.606 to 16.684, and 208Pb/204Pb ratios of 38.613 to 38.902. The S-Pb isotope data suggest derivation of S and Pb mainly from the Cretaceous granitic magma. It is concluded that the Xinmin deposit is a medium-high temperature, medium-high salinity hydrothermal polymetallic deposit, related to the granitic magmatism and strictly controlled by the fault and shattered zones.

As the core major of “Internet + Industrial Intelligence”, robotics engineering is an upgrade and reconstruction of traditional engineering major. The industrial robot course is the professional core course of the Robotics Engineering. It is also a comprehensive course of multi-discipline integration, which involved mechanical engineering, automatic control, computer, sensor, electronic technology, artificial intelligence and other multi-disciplinary content. Robotics Engineering is characterized by broad foundation, great difficulty, emphasis on practice, rapid development and application of new knowledge. In the process of implementation of the teaching innovation, the new concept of engineering education was applied to propose a new form of curriculum system. Taking the projects of engineering as the study objects, disassemble the knowledge points involved in industrial robots, break the course boundaries, reshape the knowledge system, draw knowledge maps and then design teaching activities. In teaching innovation, teachers extend classroom through formation of subject competition teams, promote teaching and promote learning by competition, realize the integration of “teaching, class and competition”, build a bridge between theory and practice, then complete the transformation from knowledge learning to ability training. Besides, they also keep contact with intelligent manufacturing enterprises in Zhuhai and the Bay Area to obtain real-time new developments in enterprises. Thus, the latest information was introduced into classroom. Therefore, the meaning of “production, teaching, research and application” has been deepened. According to the characteristics of the knowledge points of the course, experts were invited to make special lectures for students which can bring them with international perspective and frontier knowledge.

The Xiwang uranium ore deposit is one large-scale granite-hosted U deposit in the Xiazhuang U orefield in South China. Uranium orebodies occur as thin veins along the fracture zones within the Maofeng granitic pluton. Pyrite is the main sulfide mineral in the ores. Textural observation suggested that formation of hydrothermal pyrite can be divided into three stages: pre-mineralization stage pyrite (Py I), mineralization stage pyrite (Py II) accompanying with U-minerals, post-mineralization stage pyrite (Py III). In this study, in-situ sulfur isotopic compositions and trace element contents of pyrite from different stages were analyzed by laser ablation (MC-) ICP-MS methods. The δ34S values of Py I vary from −28.5‰ to −12.0‰ with an average value of −18.4‰, Py II from −15.9‰ to −10.2‰ with an average value of −12.5‰ and Py III from −22.3‰ to −14.8‰ with an average value of −19.4‰. The variations of sulfur isotopic compositions of pyrites were caused by the changes of oxygen fugacity of hydrothermal fluids. The hydrothermal fluids at the pre-mineralization stage had relatively higher oxygen fugacity (ƒO2 > 10−34). The decreasing of oxygen fugacity (to 10−36–10−35) at the mineralization stage might promote the precipitation of uraninite. The mineralization was terminated as the increasing of oxygen fugacity of hydrothermal fluids back to 10−35. Pyrite from the Xiwang deposit generally contains high U contents (up to ten thousand ppm) and very low Th contents (mostly

An investigation on the interface reactions and boron isotope fractionation in a steady-state carbonate-seawater system was performed to better understand boron incorporation into CaCO3 in a natural environment. In seawater, inorganic carbonate crystals did not precipitate even when the solution reached saturation and the presence of carbonic anhydrase enzyme promotes the process, indicating the precipitation kinetics of inorganic carbonates from natural seawater is fairly slow. Both theoretical and experimental evidence proved that boron incorporation into calcite might be defined as an adsorption-precipitation process rather than a substitution of CO32− by HBO32− in the crystal lattice, where the charged B(OH)4- ions adsorb preferentially over H3BO3 onto positively charged calcite crystal surfaces and finally co-precipitate into occlusions or inclusions after new layers of calcites formed. The Langmuir isotherm well describes the adsorption process, yielding a maximum adsorption capacity [B]solid-max of 0.33 ± 0.04 mg⋅g−1 and an equilibrium constant K of 0.0053 ± 0.0003. Langmuir kinetics also describes previous studies with [B]solid-max of 71.4–418 μg⋅g−1 for calcite and aragonite, covering the variation of boron contents in a variety of biogenic carbonates. The boron isotope fractionations in ulexite-seawater and calcite-seawater systems are distinct. In the former one the fractionation factor (αulexite-seawater = 0.995 ± 0.001) suggests that both trigonal and tetrahedral species of boron enter into ulexite crystals via rapid precipitation, and in the latter one (α4-3 = 0.9736 ± 0.004) confirms that only the charged B(OH)4- species interacts with the crystal surface in calcite.

The Shirenzhang tungsten deposit is a classic wolframite-quartz vein-type deposit located in northern Guangdong Province, eastern segment of the Nanling W-Sn polymetallic belt. The ore veins, controlled by the NW-striking fault system, are mainly hosted in the Ordovician metasedimentary rocks and can also be found with less amount in the cupola of the concealed granitic stock, displaying a typical five-floor vertical zonation proposed by the Chinese geologists. The concealed granitic stock mainly comprises two intrusive facies, the porphyritic biotite granite (G1) in the outer zone and the medium- to fine-grained monzogranite (G2) in the inner zone. In this paper, we report new cassiterite U-Pb ages and Pb isotopes of sulfides for the Shirenzhang tungsten deposit, combined with new zircon U-Pb ages and Hf isotopes, elemental geochemistry and Sr-Nd-Pb isotopes of the concealed granitic rocks, with aims to elucidate the origin of the ore-related granites and the link between the tungsten mineralization and granitic magmatism. LA-ICP-MS zircon U-Pb dating gives the weighted mean ages of 164 ± 2 Ma for G1 and 162 ± 4 Ma for G2, respectively. Cassiterite from the wolframite-bearing quartz vein and the drusy quartz vein yield the weighted mean ages of 164 ± 2 Ma and 160 ± 2 Ma, respectively. These ages suggest that both the granitic intrusion and related W-(Sn) mineralization in the Shirenzhang deposit were initiated during the late Jurassic (ca. 160 Ma). The Shirenzhang granitic rocks are weakly peraluminous highly fractionated I-type granites. Detailed elemental and isotopic data demonstrate that the granitic rocks were derived from partial melting of the Paleoproterozoic basement rocks at a relatively shallow depth of ~30 km triggered by underplating of basaltic magma, and underwent extensive fractional crystallization of hornblende, biotite, feldspar, and monazite and/or allanite. A continental arc setting induced by northwesterly subduction of the paleo-Pacific plate is suggested for the genesis of the Shirenzhang I-type granites. The comparable Pb isotopic compositions of feldspar and sulfides imply that the lead in the ore veins was of magmatic origin. Integrating the spatial-temporal relationship between the ore veins and the concealed granitic rocks with the Pb isotopes from the sulfides and granites, we suggest that the tungsten mineralization is genetically linked with the concealed granitic rocks in the Shirenzhang deposit. Fractional crystallization and melt-fluid interaction may play an important role on the formation of the granite-related tungsten mineralization.

Mafic dykes are abundant and widely distributed in many granite-hosted uranium ore deposits in South China. However, their geochronology, petrogenesis and relationship with uranium mineralization were poorly constrained. In this study, apatite U-Pb dating, whole-rock major and trace element and Sr-Nd-Pb isotope analysis were conducted for the dolerite dykes from the Aigao uranium ore deposit. Apatite U-Pb isotopic data indicate that the mafic dykes were emplaced at Early Jurassic (189 ± 4 Ma), which provides new evidence for the rarely identified Early Jurassic magmatism in South China. Pyroxene from the dykes is mainly augite, and plagioclase belongs to albite. The dolerite samples have relatively low SiO2 contents (45.33–46.79 wt%), relatively high total alkali contents (K2O + Na2O = 4.11–4.58 wt%) and Al2O3 contents (13.39–13.80 wt%), and medium MgO contents (4.29–5.16 wt%). They are enriched in Nb, Ta, Ti, rare earth elements and depleted in Rb, K, Sr, Th, showing the typical OIB-like geochemical affinity. All the dolerite samples show homogeneous Sr-Nd-Pb isotopic compositions, with (87Sr/86Sr)i varying from 0.706049 to 0.707137, eNd(t) from +4.6 to +5.2, 206Pb/204Pb from 19.032 to 19.126 and 207Pb/204Pb from 15.641 to 15.653. The mafic dykes in the Aigao deposit should be derived from the partial melting of the asthenospheric mantle and formed in a within-plate extensional environment. The emplacement age of the mafic dykes is older than the uranium mineralization age. Therefore, CO2 in ore-forming fluids couldn't originate from the basaltic magma as suggested by previous studies. The dolerite dykes might only provide a favorable reducing environment to promote the precipitation of uraninite from oxidize hydrothermal fluids.

The Dalingshang W-Cu deposit is located in the North section of the Dahutang ore field, northern Jiangxi Province, South China. Vein- and breccia-style tungsten-copper mineralization is genetically associated with Mesozoic S-type granitic rocks. Infrared and conventional microthermometric studies of both gangue and ore minerals show that the homogenization temperatures for primary fluid inclusions in wolframite (~ 340 °C) are similar to those in scheelite (~ 330 °C), but about 40 °C higher than those of apatite (~ 300 °C) and generally 70 °C higher than those in coexisting quartz (~ 270 °C). Laser Raman analysis identifies CH4 and N2 without CO2 in fluid inclusions in scheelite and coexisting quartz, while fluid inclusions in quartz of the sulfide stage have variable CO2 content. The ore-forming fluids overall are characterized by high- to medium-temperature, low-salinity, CH4, N2, and/or CO2-bearing aqueous fluids. Chalcopyrite, muscovite, and sphalerite are the most abundant solids recognized in fluid inclusions from different ores. The H-O-S-Pb isotope compositions favor a dominantly magmatic origin for ores and fluids, while some depleted δ34S values (− 14.4 to − 0.9‰) of sulfides from the sulfide stage are most likely produced by an increase of oxygen fugacity, possibly caused by inflow of oxidized meteoric waters. The microthermometric data also indicate that a simple cooling process formed early scheelite and wolframite. However, increasing involvement of meteoric waters and fluid mixing may trigger a successive deposition of base metal sulfides. Fluid-rock interaction was critical for scheelite mineralization as indicated by in-situ LA-ICP-MS analysis of trace elements in scheelite.

Mechanisms for Fe isotope fractionation in hydrothermal mineral deposits and in zones of associated K-feldspar alteration remain poorly constrained. We have analyzed a suite of bulk samples consisting of granite displaying K-feldspar alteration, Precambrian metamorphic rocks, and pyrite from gold deposits of the Jiaodong Peninsula, East China, by multi-collector inductively-coupled plasma mass spectrometry. Pyrites from disseminated (J-type) ores show a δ56Fe variation from +0.01 to +0.64‰, overlapping with the signature of the host granites (+0.08 to +0.39‰). In contrast, pyrites from quartz veins (L-type ores) show a wide range of Fe-isotopic composition from −0.78 to +0.79‰. Negative values are never seen in the J-type pyrites. The Fe isotope signature of the host granite with K-feldspar alteration is significantly heavier than that of the bulk silicate Earth. The Fe isotopic compositions of Precambrian metamorphic rocks across the district display a narrow range between −0.16‰ and +0.19‰, which is similar to most terrestrial rocks. Concentrations of major and trace elements in bulk samples were also determined, so as to evaluate any correlation between Fe isotope composition and degree of alteration. We note that during progressive K-feldspar alteration to rocks containing >70 wt% SiO2, >75 ppm Rb, and This work demonstrates that the Fe isotope composition of pyrite displays a significant response to the process of pyrite precipitation in hydrothermal systems, and that systematic fractionation of iron isotopes occurs during fluid/rock reaction in the K-feldspar alteration zone of the Linglong granite. The implications of the results are that processes of mineralization and associated fluid-rock interaction, which are ubiquitously observed in porphyry-style Cu-Au-Mo and other hydrothermal deposits, may be readily traceable using Fe isotopes.

The Wusihe carbonate-hosted Zn-Pb deposit (3.7 Mt. Zn + Pb at a grade of 8.6% Zn and 2.0% Pb) is the largest deposit in the Dadu River Valley district of the Sichuan-Yunnan-Guizhou metallogenic province of southwest China. Three types of orebodies occur: (1) stratiform, banded and lamellar, within dolomite of the Neoproterozoic Dengying Formation; (2) vein type; and (3) breccia type. Four stages of mineralization are distinguished: (i) pyrite stage, (ii) pyrite-pyrrhotite-galena-sphalerite-bitumen stage, (iii) sphalerite-galena stage, and (iv) bitumen-calcite stage. Sphalerite and galena from stages II and III show δ34S ranges from +7.1 to +9.7‰ and +9.1 to +13.1‰, respectively. High-precision in situ lead isotope analyses of sulfides show 208Pb/204Pb, 207Pb/204Pb, and 206Pb/204Pb ratios of 37.938 to 38.336, 15.579 to 15.682, and 17.951 to 18.195, respectively, which suggest a mixing of lead from the basement and the host rocks. Rb-Sr isotope analyses for six sphalerite samples of stage II yielded an isochron age of 411 ± 10 Ma (MSWD = 1.4). Combining all available ore geology and geochemical data, together with fluid inclusion data reported previously, we suggest that the Wusihe deposit is a Mississippi Valley-type (MVT) deposit.

The Liyuan lode gold deposit is located in the Shanxi province, central North China Craton. Gold orebodies are mainly hosted in Archean metamorphic rocks and structurally controlled by the NNE-trending faults. Gold occurs in disseminated and auriferous quartz-sulfide veins and veinlets within hydrothermally altered rocks. Mineralization can be divided into three intervals: (1) quartz-pyrite stage, (2) quartz-polymetallic sulfides stage, and (3) quartz-carbonate stage. Gold formed mainly in the middle stage. Sericite sample associated with the middle stage pyrite from phyllic alteration zones yields an well-defined 40Ar/39Ar plateau age of 133.3 ± 1.2 Ma, which is remarkably consistent with zircon U-Pb age (133.4 ± 1.1 Ma) of the quartz porphyry dikes in the Liyuan mine, indicating a close relationship between gold mineralization and granitic magmatism in the area. The sulfur isotopic compositions of pyrite (Py1-2) from the early stage have a narrow range from −0.3 to 4.1‰, indicating a deep-seated magmatic source. However, the sulfides (Py3-5, sphalerite, galena) from the middle stage have lower δ34SV-CDT values of −7.2 to 3.0‰, which is thought to be a result of fluid oxidation during gold mineralization. The Pb isotopic compositions of sulfides from Liyuan ores have 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios of 16.671–16.860, 15.236–15.255, and 41.452–44.159, respectively, indicting a high-thorium lower continental crust source of ore-forming materials. The δ13CVPDB and δ18OVSMOW values of late stage calcite ranging from −7.1 to −5.8‰ and 12.2 to 13.7‰, respectively, illustrating a deep-seated magmatic source of carbon-bearing portion. Given the absence of granite bodies at the present mining levels, we speculate that the ore-forming fluids may have been exsolved from a concealed granite pluton at greater depth. Based on the regional tectono-magmatic events, ore geology, geochronologic and isotopic data obtained in this study together with the previous published fluid inclusion data, we suggest that the Liyuan deposit is an orogenic gold deposit that is probably related to the early Cretaceous granite magmatism in the interior of the North China Craton.

The Jilongshan Au-Cu deposit is located in the Jiurui district of the Middle-Lower Yangtze River Metallogenic Belt in the south-eastern part of Hubei Province and close to the northern border of Jiangxi Province. This study focuses on mineral chemistry of biotite, amphibole and plagioclase in the ore-related granodiorite porphyry at the Jilongshan deposit and similar porphyry rock from the nearby Baiguoshu prospect, in an attempt to investigate the mineralization potential in the Baiguoshu area. The biotites from the Jilongshan and Baiguoshu granodiorite porphyries all belong to magnesian-biotite but the Jilongshan contains higher Mg. The calculation of Fe3 + and Fe2 + of the biotites indicated that the Jilongshan pluton shows higher oxygen fugacity that is favorable for Cu-Au mineralization, whereas the Baiguoshu pluton shows lower fO2. The Jilongshan amphiboles show higher Mg / (Mg + Fe) and lower Si which mainly belong to magnesiohornblende, whereas the Baiguoshu accommodates mainly the tschermakite. The plagioclases of the Jilongshan and Baiguoshu plutons show no compositional difference and both belong to andesine. The calculated temperatures and pressures by the coexisting amphibole-plagioclase pairs indicate that average crystallization temperature of the Jilongshan pluton is 624–736 °C and the pressure is low at 0.5–0.9 kbar, in contrast the Baiguoshu pluton shows higher temperature of 724–832 °C and higher pressure of 3.2–6.3 kbar. These data suggest that the Baiguoshu pluton has less mineralization potential than the Jilongshan pluton, therefore the Baiguoshu prospect shows less economic importance and further exploration should be carried out at depth in the Jilongshan area.

Carbonatite intrusive complexes are important hosts for Rare Earth Elements (REE) deposits and are commonly affected by surficial weathering processes. Mount Weld REE deposit of Western Australia is one of the world’s richest REE deposits and here we present whole-rock and REE mineral geochemical data on compositions of primary and weathered carbonatites. The REE concentrations in magmatic carbonatites at Mount Weld vary by two orders of magnitude, suggesting a significant role of magmatic processes in REE enrichment in the carbonatite complex. The Th-Pb age 2056±67 (2σ) Ma of monazite-(Ce) from the carbonatite obtained by in situ LA-ICP-MS analyses confirm Paleoproterozoic age of the mineralization. The regolith samples preserve a detailed record of evolution from carbonatite to products of intensive weathering. The silica-cemented regolith (silcrete) contains monazite-(Ce) and apatite chemically identical to their carbonatite-hosted equivalents. The high-REE regolith containing 51.8 wt% ∑REE2O3 has some of the highest REE concentrations found to date, negative Ce anomaly and contains lithogenic monazite within matrix of florencite-(Ce) and rhabdophane-(Nd) and rhabdophane-(Nd) tubes resembling casts of plant material. The pronounced negative Ce anomalies in the ferruginous cap rock (ferricrete) and the high-REE regolith indicate intensive weathering, where Ce4+ was preferential removed relative to the REE3+. The presence of paleo-plants in the high-REE regolith implicates bio-assisted processes involved in the extreme REE fractionation. The diverse REE enrichment processes, which occurred in supergene environment of Mount Weld, have implications for the understanding of the genesis of REE deposits worldwide.

The North Wuyi area occurs a number of important Cu-Pb-Zn polymetallic deposits in southeastern China, but most of them are of Jurrasic-Cretaceous ages (Yanshanian). Here we report that the Chenfang skarn Fe-Cu-Sn polymetallic deposit is a new Triassic (Indosinian) deposit firstly confirmed by direct age dating of ore mineral cassiterite in this area. Zircon U-Pb dating of the biotite granite yielded an age of 226.4 ± 1.5 Ma. The U-Pb ages of cassiterite from massive magnetite (230.3 ± 3.6 Ma) and banded magnetite (222.5 ± 2.5 Ma) are consistent with the U-Pb age of biotite granite, suggesting the mineralization has a close genetic relationship with the biotite granite. The biotite granite is characterized by highly siliceous (SiO2 = 75.02–77.33 wt%), high alkali (Na2O + K2O = 7.93–9.24 wt%) and strongly perlauminous (A/CNK = 1.31–1.33). The zircons from the biotite granite characterized by low eHf(t) values between −10.3 and −5.6, with Hf model ages between 1884 Ma and 1591 Ma, indicating that the magma derived mainly from partial melting of Proterozoic crustal source. The Indosinian magmatic–hydrothermal metallogenic event reported in this study, together with previous studies, suggest in the North Wuyi area occurs at least three main magmatic-hydrothermal events, namely, the Middle-Late Triassic (230 Ma to 226 Ma), Late Jurassic (160–154 Ma), and Early Cretaceous (139–136 Ma). Therefore, mineralization in the North Wuyi area has experienced a long evolution, and more attention for future exploration should put in the early Indosinian magmatic–hydrothermal ore deposits.

The Shihuiyao deposit is a recently discovered giant Rb deposit in association with other rare metals (Nb-Ta-Be-Li) in Inner Mongolia of northeastern China. Six ore-bearing plutons were emplaced at the Late Jurassic (ca. 145 Ma) in the Shihuiyao mining area and composed of siderophyllite monzogranite, muscovite granite, muscovite–albite granite, zinnwaldite–albite granite, and zinnwaldite–amazonite granite. Micas in these granites include siderophyllite, muscovite and zinnwaldite, and they show an increase of Rb2O and F contents and decrease of K2O/Rb2O ratios, reflecting the magmatic fractionation evolution trend. Field relationships, whole-rock data, and mineralogical features do not show a continuous progression of these granites in the Shihuiyao deposit, which can be interpreted as that they experienced different fractional processes in the magma source. Hence, combined with field evidence and Nd isotopic composition, a model was established for the petrogenesis of these granites. The oceanic slab tear led to rapid asthenosphere upwelling, which causes the partial melting of a Neoproterozoic juvenile crust, i.e., a mixed lithology composed of a major mantle-derived component with less amount of ancient crust component. Initial magmas ascended and accumulated to form a magma chamber in the upper crust. Magmas in the chamber underwent a series of fractional processes and were then discharged by a series of intrusive magmatic activities, thus forming the ore-bearing granites in the Shihuiyao mining area. In the late stages of magmatic fractionation, co-existing aqueous hydrothermal fluids most likely controlled the trace element distribution in these ore-bearing granites. In the Shihuiyao deposit, not only the fractional crystallization of magma, but also the hydrothermal fluids, exsolved from the magma and extracting elements from the wall rocks or primary granite phases, played an important role in Rb mineralization. Also, the content of F in the melt may affect the enrichment of Rb. The presence of a deep magma chamber suggests that the Shihuiyao and its surrounding areas have good prospecting potentials for rare metals mineralization.

In order to trace chlorine and sulfur evolution during magma evolution, detailed petrographic observation, major- and trace-element analysis of amphibole and apatite were carried out on the ore-related pluton in the Tonglvshan Cu-Fe (Au) skarn deposit, Hubei Province, South China. Several generations of apatite and amphibole are identified, from early to late including: (1) apatite in euhedral amphibole; (2) euhedral amphibole; (3) apatite in subhedral-anhedral amphibole/plagioclase; (4) subhedral-anhedral amphibole + plagioclase; (5) apatite in K-feldspar or quartz; and (6) K-feldspar + quartz. Most apatites show homogeneous textures, but a few apatite grains enclosed in amphibole and plagioclase (1 and 3) display oscillatory zoning. These zoned apatites crystallized in semi-closed environments created as growth of amphibole or plagioclase removed components of the melt. The magmatic Cl and S evolution can be divided into three stages: (I) In the deep magma chamber, at ∼ 5 km below the surface, magma underwent ∼ 39% fractional crystallization, and its Cl and S contents increased simultaneously; (II) In a shallow magma chamber at ∼ 2.5 km depth, fractional crystallization elevates Cl and S contents in the residual melt, but fluid exsolution depletes them; (III) At near-solidus stage, when fluid exsolution becomes weak, crystallization elevates Cl and S contents in the residual melt simultaneously. This study suggests that the silicate mineral (fractional) crystallization can elevate Cl content in residual melt, and fluid exsolution can efficiently remove Cl from the magma. Bulk sulfur in magma may be transported not only as dissolved sulfur, but also as sulfates like anhydrite. The sulfur content of apatite is controlled by the sulfur composition in melt from which the apatite crystallizes, but Cl in apatite may represent re-equilibration between the apatite and the last melt in contact with the apatite, because of rapid diffusion of Cl in apatite. These characteristics along with complex apatite generations imply that in-situ study is necessary when using apatite to trace volatile composition in magma.

Because of the large-scale recycling of volatile chlorine from the interior to the surface of the Earth, it is possible to use the isotopic composition of this element (δ37Cl) in serpentinite to study mantle-crust interactions in subduction zones. It is also possible to use chlorine isotopes to track the evolution of fluids (through fluid inclusions/minerals) in hydrothermal ore-forming systems. Here, we report the results of a study of equilibrium chlorine isotope fractionation during serpentinization and hydrothermal mineralization based on density functional theory (DFT) and ab initio molecular dynamics simulations (AIMD). The chlorine isotope fractionation between lizardite and brine under variable thermodynamic conditions is described by the relationship 1000lnαlizardite-fluid = 0.4170 × (1000/T)2–0.0281 × (1000/T) + 0.0582, which yielded Δ37Cllizardite-fluid values of +0.49 to +4.46‰, +0.41 to +0.59‰ and + 0.49 to +3.57‰ for conditions at the seafloor, in the mantle wedge and in subduction zones. As a proxy for the diversity of metal-chloride complexes in hydrothermal fluids, the stable configurations of ferrous chloride complexes were acquired from long trajectories of AIMD simulation. Using this information, the chlorine isotope fractionation between minerals (i.e., apatite-group minerals, muscovite, phlogopite, tremolite, lizardite, marialite and metal halides) and ore-forming fluid was estimated. The relatively large chlorine isotope fractionation (Δ37Cl minerals-hydrothermal fluid values from −1.99 to +2.18‰) might partly explain the large variation of δ37Cl in individual fluid inclusions observed in hydrothermal ore deposits. Because of the limited chlorine isotope fractionation between apatite and hydrothermal fluid (i.e., Δ37Cl apatite-ore-forming fluid of 0.06‰–0.69‰), apatite-group minerals might be an alternative to fluid inclusions for constraining the origin and evolution of hydrothermal fluids using δ37Cl values. The theoretical constraints provided in this paper will facilitate the use of chlorine isotopes in tracking the sources of chloride in subduction zones and the origin of mineralizing fluids in ore deposits.

Triassic magmatism in Thailand provides the critical geological record for understanding the evolution of the Paleo-Tethys Ocean. This paper presents zircon U-Pb dating, zircon trace element compositions, elemental geochemistry and Sr-Nd-Hf isotopes for the newly identified Late Triassic granite intrusions in the Upper Peninsula of Thailand where voluminous Late Cretaceous-Paleogene granite intrusions occur. Zircon U-Pb dating results indicate that the two-mica granites were emplaced at ca. 217–216 Ma. The unaltered two-mica granite samples are high silicic (SiO2 = 74.03–75.06 wt%) and display strongly peraluminous characteristics, with A/CNK ratios of 1.21–1.33 and CIPW normative corundum contents of 2.86–3.88 wt%. They have fractionated REE patterns ((La/Yb)N = 5.64–7.34) and notable negative Eu anomalies (Eu/Eu* = 0.35–0.49), with enrichment of Rb, Th, U, Ta and Pb and depletion of Ba, Nb, Sr and Ti. The two-mica granites can be assigned as the highly fractionated S-type granites. They have negative whole-rock eNd(t) (−13.2 to −12.3) and zircon eHf(t) (−11.5 to −7.4) values with corresponding two-stage Nd and Hf model ages ranging from 1.99 to 2.06 Ga and from 1.72 to 1.98 Ga, respectively, indicating a Paleoproterozoic crustal source. The combined geochemical and isotopic data reveal that these rocks were derived by fluid-absent muscovite melting of metapelite at the middle-upper crustal depths and modified by fractional crystallization. In combination of the results in this study with regional geological data, it can be concluded that the two-mica granites were more likely formed during the post-collisional stage of the Sibumasu-Indochina collision, induced by slab break-off of the Paleo-Tethys Ocean. Based on the integrated consideration of a set of factors, including temporal and spatial proximity, source lithology and source enrichment, redox state, and fractional crystallization coupled with melt-fluid interaction, it is suggested that the ca. 216 Ma two-mica granites exhibit high Sn mineralization potential and could be helpful for exploring the primary Sn deposit of Late Triassic age nearby.

Although quartz vein-type deposits are extremely common worldwide, their formation age is difficult to determine due to the lack of suitable minerals for precise isotope dating. In this article, we report a case study from the large Qipangou quartz vein-type tungsten deposit (57,400 t@ 1.08–1.09 wt% WO3) in the South Qinling polymetallic ore belt, Shaanxi Province, Central China, in which the mineralization event was precisely dated using hydrothermal titanites that are co-genetic with ore minerals. Our results show that although granite is absent in the Qipangou mining district, the titanite U–Pb ages of 194.2 ± 3.6 Ma (sample 18QPG-29) and 198.6 ± 2.1 Ma (sample 18QPG-31) corresponded with that of regional granites and other W–Mo deposits (approximately 200–190 Ma) in the ore field, suggesting a temporal link between this quartz vein-type deposit and granitic magmatism in the region. This study represents the first hydrothermal quartz-vein tungsten deposit analysis using in situ U–Pb isotope dating of titanite, and the results indicate that titanite U–Pb dating can be a potential method for constraining the age of this type of deposits. Based on petrography and mineral assemblage, titanite can be classified as two types. Compositional differences between these two types likely indicate different fluid sources, the release of elements into the local fluid system during alteration such as the decomposition of rutile and hydrous mineral phases like phlogopite, and the addition of components from host sedimentary strata.

Except for extensive studies in core formation and volatile-element depletion processes using radiogenic Ag isotopes (i.e. the Pd-Ag chronometer), recent research has revealed that the mass fractionation of silver isotopes is in principle controlled by physico-chemical processes (e.g. evaporation, diffusion, chemical exchange etc.) during magmatic emplacement and hydrothermal alteration. As these geologic processes only produce very minor variations of δ109Ag from -0.5 ‰ to +1.1‰, more accurate and precise measurements are required. In this work, a robust linear relationship between instrumental mass discrimination of Ag and Pd isotopes was obtained at the Ag/Pd molar ratio of 1:20. In Au-Ag ore-deposits, silver minerals have complex paragenetic relationships with other minerals (e.g. chalcopyrite, sphalerite, galena, and pyrite etc.). It is difficult to remove such abundant impurities completely because the other metals are tens to thousands of times richer than silver. Both quantitative evaluation of ma...

The Baiguoyuan Ag-V ore deposit in Xingshan County, Hubei Province, is hosted in Neoproterozoic black shale, containing approximately 1860 tons Ag at average grade of 116 g/t and 21.8 Mt. V at average grade of 1.5%. The occurrence, source and enrichment mechanism of silver in this deposit are still a topic of debate. In this study, we applied high-resolution electron microprobe analysis (EMPA) and LA-ICP-MS technique to determine the occurrence of silver and to infer its source and enrichment mechanism. Mineralography observation revealed that pyrite is the main metallic mineral in the ores, which shows three-stage formation histories: (1) sedimentation, (2) diagenesis, and (3) deformation. BSE imaging detected tiny naumannite inclusions in pyrite. EMPA showed high contents of Ag in sedimentary pyrite. LA-ICP-MS analysis displayed both solid solution and tiny naumannite inclusion of Ag in pyrite. A mass balance calculation suggested that Ag occurred mainly as solid solution and minor as tiny naumannite inclusions in pyrite. The high contents of Co and Se, and high ratios of Co/Ni and Se/S in sedimentary pyrite indicated that Ag was probably supplied by submarine hydrothermal venting. The correlation between Ag and Fe or Se in sedimentary pyrite indicated that Ag was enriched through Ag and Se replacing Fe and S in pyrite, respectively.

Wide bandwidth, wide tunable phase range, and a compact circuit size are always desired for the tunable phase shifter utilized in the modern wireless communication system. However, the existing reflection-type phase shifter configurations cannot satisfy all these requirements simultaneously. To resolve these problems, the reflection load consisting of two tunable capacitors and a quarter wavelength transmission line is utilized on a vertically installed planar structure to implement a new reflection-type phase shifter. For demonstration, a reflection-type phase shifter is designed, fabricated, and measured. A wide bandwidth of 66.7% defined by 10-dB return loss had been achieved. Over the same band, a wide phase shift range up to 407° can be observed. Meanwhile, the fabricated circuit occupies a compact circuit size of ${0.26\lambda _{g} *0.37\lambda _{g}}$ .

The Miaoya carbonatite complex in the South Qinling orogenic belt hosts one of the largest rare earth element (REE)-Nb deposits in China that is composed of carbonatite and syenite. The emplacement age of the complex and the geochronological relationship between the carbonatite and syenite have long been debated. In this study, in situ U–Th–Pb ages have been obtained for the constituent minerals zircon, monazite and columbite from carbonatite and syenite of the Miaoya complex, together with their chemical and isotopic compositions. In situ trace element compositions for zircon from carbonatite and syenite are highly variable. The zircon displays slightly heavy REE (HREE)-enriched chondrite-normalized patterns with no Eu anomaly and various light REE (LREE) contents. In situ Th–Pb dating for zircon from the Miaoya complex by laser ablation ICP-MS yields ages of 442.6 ± 4.0 Ma (n = 53) for syenite and 426.5 ± 8.0 Ma (n = 23) for carbonatite. Monazite from carbonatite and syenite shows similar chondrite-normalized REE patterns and yields a consistent Th–Pb age of ~ 240 Ma. Based on petrographic and chemical composition, columbite from the carbonatite can be identified into two groups. The columbite dispersed within carbonatite is characterized by slightly LREE-enriched chondrite-normalized REE patterns, whereas columbite associated with apatite is characterized by LREE-depleted trends. Columbite has been further determined to have a weighted mean 206 Pb/ 238 U age of 232.8 ± 4.5 Ma (n = 9) using LA-ICP-MS. Detailed geochronological and chemical investigations suggest that there were two major episodes of magmatic/metasomatic activities in the formational history of the Miaoya carbonatite complex. The early alkaline magmatism emplaced in the Silurian was related to the opening of the Mianlue Ocean, whereas the late metasomatism or hydrothermal overprint occurred during the Triassic South Qinling orogeny. The latter serves as the major ore formation period for both REE (e.g., monazite) and Nb (e.g., columbite).

The existing tunable circuits mainly concentrate on the control of frequency and amplitude. The control of phase characteristics becomes more and more important in the modern system for further performance enhancement. But none of existing coupler configurations can achieve this tunability. A novel hybrid coupler with simultaneous phase- and frequency-tunable characteristics is presented for the first time. Varying the difference between the capacitances for two rows of tunable capacitors loaded on the branch lines can provide different phase differences between two output ports with equal magnitude. Based on the same circuit, a tunable operating frequency can be realized while maintaining the equal power division and desired phase characteristics. This is achieved by simply changing the capacitances for two rows of tunable capacitors in unison. The high flexibility to achieve tunability in phase and frequency simultaneously is implemented. For demonstration purposes, a hybrid coupler operating at 1 GHz is designed and measured to validate the concept. It exhibits a variable phase difference from 45° to 135° while maintaining equal power division. Meanwhile, the same circuit gives a tunable operating frequency extending from 0.8 to 1.1 GHz while maintaining good performance for a 3 dB coupler with a tunable phase difference from 50° to 130°.

The postmatching topology is an effective approach for broadening the bandwidth of a Doherty power amplifier (DPA). Its efficiency can be enhanced using a second-harmonic short-circuit network (SHSN), but at the expense of bandwidth. In this paper, the SHSNs with mutual coupling are proposed to achieve efficiency enhancement without sacrificing bandwidth. A broadband Doherty amplifier was designed and fabricated based on commercially available gallium nitride HEMT (Cree CGH 40006P) devices to validate the proposed technique. Under continuous-wave excitation, the measured results of the proposed DPA demonstrated that a wide bandwidth of 40% (1.8–2.7 GHz) can be maintained, with the 6-dB back-off drain efficiency between 47.5% and 54%. Using a wideband code-division multiple access 3GPP test signal with the peak-to-average power ratio of 6.6 dB, the adjacent channel power ratio over the entire frequency band is below −30 and −25 dBc at a 6-dB back-off and saturation, respectively.

The several-hundred-m-thick Eocene-Oligocene volcanic units in the Urmia-Dokhtar magmatic arc in northwestern Central Iran host stratabound and fault-controlled copper mineralization. The Kuh-Pang deposit (2.8 Mt at 1.65 wt% Cu, 0.52 g/t Au, 34 g/t Ag) has vein-style copper mineralization, with primary Cu-sulfides of chalcopyrite, bornite, chalcocite and digenite, and supergene Cu-sulfides of chalcocite, covellite, malachite and azurite, in a tectonic–hydrothermal breccia zone within rhyodacite and andesite flows. The mineralization is accompanied by a variety of alterations including silicic, carbonate, argillic and advanced argillic within a broad-scale propylitic halo. The main ore formation is related to hydrothermal breccias, and has a close association with silicic and argillic alterations. Sulfides formed during hydrothermal alteration, as indicated by: 1) the occurrence of disseminated sulfides in the groundmass of hydrothermally altered rocks, 2) the co-precipitation of sulfides and alteration minerals (e.g., kaolinite, alunite) in the cement of hydrothermal breccias, and 3) the occurrence of sulfides filling fissures and voids of hydrothermally altered rocks (vuggy quartz). The main mineralization stages include: (i) pre-ore stage with pyrite and arsenopyrite, (ii) main ore-stage with chalcopyrite, bornite, chalcocite I and digenite, and (iii) late-ore and supergene enrichment stage with chalcocite II and covellite. Electron microprobe analyses of pyrite show that As, Cu and Co are the most abundant minor elements. Back-scatter electron imaging of pyrite shows zoning features that closely reflect variations in the As/S ratio. High Cu concentration in pyrite is probably related to the presence of sub-micrometer particles and aggregates of chalcopyrite or other Cu-bearing sulfide minerals. Silver is preferentially enriched in supergene chalcocite and covellite. The mineral assemblage indicates a trend from intermediate to high sulfidation state, and arsenopyrite geothermometry defines temperatures for the pre-ore sulfides ranging from 250 to 370°C. The sulfur isotope composition of pre-ore pyrite and arsenopyrite shows a δ34S range of −1 to 3‰, indicating a magmatic sulfur-source. The copper sulfides have lower δ34S values (−9 to −3‰), indicating that the ore-forming fluids gradually became SO42−-enriched and relatively oxidized during Cu mineralization. The tectono-magmatic setting, mineral assemblage and hydrothermal alteration, including advanced argillic and silicic zones, suggest that the Kuh-Pang copper deposit is a high sulfidation epithermal deposit in a volcanic arc terrain.

This study reports a detailed evaluation of how key parameters of operation influence the measurement of sulfur isotopes using laser ablation multiple collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS). Sulfur isotopes are observed to display a fractionation up to 2‰ δ34S during analysis of pyrite with different laser parameters using a 193 nm ArF excimer laser. In order to understand why the laser parameters affect S isotope fractionation when measuring S isotopes in pyrite, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) techniques were used to characterize debris formed during the ablation of pyrite, i.e., morphology and speciation of phases. The results show that pyrite decomposes to two phases: ball-like troilite (FeS) and a sulfur-rich floc-like agglomeration surrounding the troilite. The measured δ34S values vary due to the different proportions of troilite balls and the floc-like material generated under different laser parameters. The proportion of troilite and S was evaluated with a LA-(Quadrupole)-ICP-MS through direct comparison of the counts per second (CPS) ratio of 56Fe to 32S. In contrast to pyrite, natural pyrrhotite shows no decomposition process and the particle size of the debris from pyrrhotite is nearly 10 times larger than that of pyrite (~ 5 μm for pyrrhotite compared to

The conventional differential phase shifter configurations usually require different reference lines to provide constant phase shifts over a certain bandwidth. This results in high design complexity, especially for the multiway and poly-phase applications. To solve this problem effectively, a new differential phase shifter configuration based on the parallel stubs loaded transmission line is proposed. The phase of different main lines in the proposed structure can be easily aligned with that of the same reference line by simply changing the position of the loading stubs, which has a linear relationship with the desired phase shift. The new phase aligning approach and the universal reference line bring about simplicity in design and implementation. For demonstration purposes, a group of differential phase shifters is designed, fabricated, and measured. The corresponding constant phase shifts (from 45° to 135° with a step of 15°) are obtained between the main lines and the reference line, over a bandwidth of 55.6% with small insertion loss and phase deviation.

In a conventional differential phase shifter (DPS), to realize arbitrary phase shifts, the reference and main microstrip lines are of different lengths. This difference results in suboptimal integration density, which renders the wireless communication system implementation complex and bulky. This paper presents an equal-length multiway DPS based on metamaterials. The reference lines have identical dimensions and are of equal lengths with the main lines. The proposed structure covers a wide bandwidth by aligning the main line phase slope without degradation in return and insertion losses. A design optimization methodology is presented for wideband DPSs in the 0°-90° range. For demonstration, a six-way DPS has been designed and fabricated. The measurements show that the phase shifters have less than 5° differential phase stability and better than a 10-dB return loss, with an insertion loss less than 1.24 dB from 1.6 to 3.2 GHz.

The biotite pegmatites in the Shangdan domain of the North Qinling orogenic belt contain economic concentrations of U, constituting a low-grade, large-tonnage pegmatite-hosted uraniferous province. Uraninite is predominant and ubiquitous ore mineral and coffinite is common alteration mineral after initial deposit formation. A comprehensive survey of the uraninite and coffinite assemblage of the Chenjiazhuang, Xiaohuacha, and Guangshigou biotite pegmatites in this uraniferous province reveal the primary magmatic U mineralization and its response during subsequent hydrothermal events. Integrating the ID-TIMS (Isotope Dilution Thermal Ionization Mass Spectrometry) 206Pb/238U ages and U-Th-Pb chemical ages for the uraninites with those reported from previous studies suggests that the timing of U mineralization in the uraniferous province was constrained at 407&ndash, 415 Ma, confirming an Early Devonian magmatic ore-forming event. Based on microtextural relationships and compositional variation, three generations of uranium minerals can be identified: uaninite-A (high Th-low U-variable Y group), uranite-B (low Th-high U, Y group), and coffinite (high Si, Ca-low U, Pb group). Petrographic and microanalytical observations support a three-stage evolution model of uranium minerals from primary to subsequent generations as follows: (1) during the Early Devonian (stage 1), U derived from the hydrous silicate melt was mainly concentrated in primary magmatic uaninite-A by high-T (450&ndash, 607 &deg, C) precipitation, (2) during the Late Devonian (stage 2), U was mobilized and dissolved from pre-existing uraninite-A by U-bearing fluids and in situ reprecipitated as uraninite-B under reduced conditions. The in situ transformation of primary uraninite-A to second uraninite-B represent a local medium-T (250&ndash, 450 &deg, C) hydrothermal U-event, and (3) during the later low-T (100&ndash, 140 &deg, C) hydrothermal alteration (stage 3), U was remobilized and derived from the dissolution of pre-existing uraninite by CO2- and SiO2-rich fluids and interacted with reducing agent (e.g., pyrite) leading to reprecipitation of coffinite. This process represents a regional and extensive low-T hydrothermal U-event. In view of this, U minerals evolved from magmatic uraninite-A though fluid-induced recrystallized uraninite-B to coffinite, revealing three episodes of U circulation in the magmatic-hydrothermal system.

The processes that caused the heterogeneity of δ37Cl in the Earth's mantle are unclear. Here we report theoretical estimates of equilibrium chlorine isotope fractionation among common chlorine-bearing minerals, namely apatite-group minerals (Cl-Ap, F-Cl-Ap, OH-Cl-Ap), muscovite, phlogopite, tremolite, lizardite, marialite and metal halides, based on first-principles calculations, and use them to provide an explanation for this heterogeneity. Our results show that at ambient P-T conditions, the reduced isotopic partition function ratio (β-factor) is strongly correlated with the metal-Cl bond length/bond strength of the above minerals and that phlogopite and muscovite are more enriched in 37Cl than other minerals. As a result of a number of factors, including the adjacent atomic environment, the sites occupied by chlorine atoms in crystals, the Cl-metal coordination and the crystal density, the sensitivity of 103lnβ to pressure follows the sequence: halite > fluoro-chlorapatite > chlorapatite > marialite > hydroxyl-chlorapatite > lizardite > tremolite > muscovite > phlogopite. Estimates of the chlorine isotope fractionation between chlorine-bearing minerals and aqueous fluid at the pressure and temperature prevailing during subduction indicate that the δ37Cl values of mantle minerals could vary between −6‰ and + 3‰, assuming equilibrium. In contrast, the average δ37Cl value of the bulk mantle is −0.53 ± 0.16‰. Thus, large-scale recycling of volatile Cl from the deep mantle to the continental/oceanic crust and ocean, and the isotopic fractionation of chlorine with increasing metamorphic grade during subduction, could explain the heterogeneity of δ37Cl values observed in mantle materials.

The Qingyunshan Cu-Au deposit, located in the Dehua-Youxi area (Fujian Province, southeastern China), is a vein-type deposit that occurs along fractured zones in the Late Jurassic volcanic-sedimentary rocks and Early Silurian intrusions. Three mineral paragenetic stages are identified, including the pyrite-quartz veins (stage I), polymetallic sulfide-quartz-calcite veins (stage II), and calcite (±siderite)-chalcedony-comb quartz veins (stage III). The stage II is the main mineralization stage, dominated by pyrite, chalcopyrite, and galena as well as two generations of Fe-poor sphalerite with average Fe content of 0.84 wt% in the early sub-stage and 0.31 wt% in the late sub-stage. Fluid inclusion studies indicate that the stage I has a temperature of 220–240 °C and salinity of 3.00–3.50 wt% NaCleq., whereas the stage II has lower temperature (140–160 °C), but similarly low salinity (2.50–3.00 wt% NaCleq.), suggesting it is an intermediate-low temperature epithermal deposit. Hydrogen and oxygen isotope data indicate the fluids of stage I has a δD value of −72.5 to −69.5‰ and δ18Ow value of −2.96 to −0.46‰, whereas the stage II fluids show similar or slightly higher δD value (−68.0 to −66.5‰), but significantly lower δ18Ow value from −6.96 to −6.26‰, which suggest meteoric water predominated in the ore-forming fluid and shows an increasing trend from stage I to II. The δ34S values of sulfide minerals are between −3.7 and −2.3‰, consistent with a major magmatic sulfur source. The lead isotope data show a relatively narrow range with 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb values of 18.392–18.513, 15.642–15.758, and 38.497–39.043, respectively. These Pb-isotope data are similar to those of the Late Jurassic intrusions, but quite different from those of the surrounding rocks of Early Silurian quartz diorite. Pyrite from the ores yielded a Re-Os isochron age of 158.1 ± 9.3 Ma, which is similar to the zircon U-Pb age (162.0 ± 1.0 Ma) of the host dacite crystal tuff in the Nanyuan Formation. Therefore, we concluded that the Late Jurassic magmatic activity (ca. 160 Ma) has a genetic relation with formation of the Qingyunshan vein-type Cu-Au deposit, for which the ore metals were mainly derived from the magma, but ore-forming fluids evolved from a mixing of magmatic fluids and meteoric water with the later playing a major role in the main stage of ore formation.

Although it is well known that many peralkaline granite plutons show enrichment of the rare earth elements (REE) and other high field strength elements (HFSE), the magmatic-hydrothermal processes that concentrate these elements are still poorly understood. The Early Cretaceous Baerzhe pluton in northeastern China provides an ideal example of super-enrichment in REE, Zr, Nb and Be in peralkaline granites. Three kinds of granites are identified, namely, the barren, the moderately-mineralized and highly-mineralized granites. The barren granite includes hypersolvus porphyritic arfvedsonite granite, transsolvus fine-grained granite, as well as transsolvus pegmatite and aplite; the moderately-mineralized granite includes transsolvus spherulitic granite and coarse-grained granite; and the highly-mineralized granite is subsovlus and contains spherulitic granite and medium-grained granite. Replacements of arfvedsonite by aegirine and alkaline feldspar by albite occurred in the moderately-mineralized granite, whereas an extensive alteration assemblage of Fe-Ti oxides and albite laths developed in the highly-mineralized granite. The barren porphyritic arfvedsonite granite samples show moderate SiO2 (63.20–68.00 wt%), high total alkali (Na2O + K2O = 9.94–10.23 wt%), and variable and high total FeO contents (7.56–13.45 wt%). The barren fine-grained granite, as well as moderately-mineralized spherulitic granite and coarse-grained granite, are characterized by high SiO2 (73.21–75.92 wt%), high total FeO (1.04–5.44 wt%) and total alkali (Na2O + K2O = 8.72–9.85 wt%) concentrations with A/CNK = 0.80–0.99 and NK/A = 1.00–1.24, indicative of peralkaline affinity. In comparison, the highly-mineralized spherulitic granite and medium-grained granite have more variable SiO2 (72.10–79.50 wt%) and lower total alkali (K2O + Na2O = 4.40–8.70 wt%) contents. All these samples have positive and uniform eNd(t) varying from + 2.25 to + 3.28, along with restricted 206Pb/204Pb (18.107–18.464) and 207Pb/204Pb ratios (15.497–15.549), showing that they were probably derived from a common juvenile melt. When compared with the barren fine-grained granite, the spherulitic granite contains more microcline and albite but less perthite, suggesting the spherulitic granite formed in a more evolved magma. The amounts of spherulites are in direct proportion to the intensity of hydrothermal alteration and mineralization. It is suggested that the spherulite structure was a product of low nucleation rates due to the high volatile content of the late-stage evolved magma. Extensive magma differentiation leads to the exsolution of F- and Cl-rich hydrothermal fluids which are enriched in large amount of REE and HFSE elements. Furthermore, intense fluid-rock interaction occurred in the most advantage stage of magmatic-hydrothermal evolution and led to extensive alteration as well as the formation of associated REE-Zr-Nb-Be mineralization in the large Baerzhe deposit.

The Zhaojinggou rare-metal deposit is located in the Wulashan-Daqingshan region, central north margin of the North China Craton. Nb-Ta mineralizations are mainly hosted in the biotite alkali-feldspar granite (BAG) and albite granite (AG), with subordinate mineralization in the alkali-feldspar aplite dyke (AFA), the amazonite granitic pegmatite dyke (AGP), and the greisen (black + white colored greisen). In this paper, we present a systematic work of geochronology (CGM U-Pb combined with cassiterite U-Pb, monazite U-Th-Pb, and muscovite 40Ar-39Ar dating), whole-rock geochemistry, and Sr-Nd isotopes to understanding the timing of mineralization, petrogenesis, geodynamic setting, and ore-forming processes. Our geochronological data reveal two episodic Nb-Ta mineralization events in the Zhaojinggou deposit during the Early Cretaceous. The first and major ore-forming episode occurred at ~130 Ma, forming a sequence of ore-bearing rocks of the BAG-AG-greisen-AFA. The second but subordinate ore-forming episode occurred at ~114 Ma, forming the ore-bearing AGP. The whole-rock geochemistry indicates the granitic rocks (the BAG-AG-AFA and AGP) from the two episodes are highly evolved with analogous trace element and REE patterns, and have A-type affinity. The whole-rock eNd(t) values of these granitic rocks are relative similar, ranging from −9.6 to −7.6, with corresponding T2DM ages of 1490–1713 Ma. These features suggest that these A-type granites from the two discrete episodes are derived from the same magma reservoir by high-temperature partial melting of the Middle Proterozoic basement in an infracrustal extensional environment. These A-type granites experienced extremely fractional crystallization during emplacement. The whole-rock REE tetrad effects, element ratios (Nb/Ta, Zr/Hf and K/Rb), and Nb-Ta fractionation modeling indicate that both magmatic and hydrothermal processes are involved to form the two episodic Nb-Ta mineralizations. High degree of factional crystallization and magmatic-hydrothermal processes after high-temperature anataxis are crucial to form the Zhaojinggou rare-metal deposit. Moreover, these highly-evolved A-type granites (the BAG-AG-AFA and AGP) formed during the Early Cretaceous (at ~ 130 Ma and ~ 114 Ma respectively) are the important targets for rare-metals prospecting in the central north margin of the NCC.

Apatite is a ubiquitous mineral in granites and crystallizes from the beginning of magma evolution to the latest magma-fluids transitional stage, and thus, is able to record petrogenetic-metallogenic information. In order to figure out the role of granites in the formation of the Zhuxi deposit, textures and compositions of apatites in the Zhuxi granites were investigated. Granites related to the Zhuxi W-Cu deposit include biotite granite, muscovite granite, and granite porphyry. Apatites in these granites are named Group A, Group B (core – Group B1; rim – Group B2), and Group C, respectively. Along this sequence, geochemical characteristics of apatites show gradual enrichment of total rare earth elements (ΣREE), high-field strength elements (HFSE; Th, U, Nb, Ta, Zr, and Hf), as well as ore-forming element W, and depletion of Sr. Meanwhile, Ga content in these apatites consecutively increased, indicating the reduction of oxygen fugacity in the Zhuxi magmatic system. Non-chondritic Y/Ho (mostly > 34) and Zr/Hf (broadly

Engineering education professional certification is an internationally accepted engineering education quality assurance system and an important basis for realizing international mutual recognition of engineering education and engineer qualification. The purpose is to ensure that engineering graduates have the comprehensive ability to adapt to social engineering work. The evaluation is oriented by training objectives and graduation requirements. There are seven aspects of engineering education professional certification, of which the most core is students. The ultimate goal is to meet the graduation requirements, and the specific guarantee is the training goal. Passing the engineering education certification has become an important work of undergraduate education and training. Based on engineering certification and under the guidance of the goal of software engineering major of Software College of Beijing University of technology, this paper compares the syllabus of software process and project management in 2015 and 2020. This paper makes a detailed comparative analysis from the aspects of teaching objectives, teaching contents, teaching methods and assessment methods. The comparison results show that the revision of the curriculum according to the engineering certification has brought more positive changes. It is hoped that the results of the reform can provide some inspiration to relevant teaching personnel.