The Paleo-Tethyan arc belt is of enormous scale, but hosts few porphyry Cu-Au deposits. Previous studies suggest that the arc magmas are overall reduced and infertile during Permian-early Triassic. Nevertheless, the tectonic evolution and Cu-Au fertility of early-stage (Late Devonian to Carboniferous) Paleo-Tethyan arc magmatism remain poorly understood. Here, we address these issues by investigating the petrogenesis and fertility of a newly identified Late Devonian granodiorite intrusion (Gucaicun, 362.4 +/- 2.3 Ma) in eastern Tibet. The granodiorite is calc-alkaline to high-K calc-alkaline in composition, and shows enrichment in LILEs but depletion in HFSEs, which are diagnostic of arc magmatism. Whole-rock trace elemental characteristics (e.g., Rb vs. Yb + Nb, Th/Yb vs. Nb/Yb) indicate that this intrusion was formed in a continental arc setting. Depleted whole-rock Sr-Nd and zircon Hf isotopes [(87Sr/86Sr)i = 0.704368-0.704427; epsilon Nd(t) = 3.9-4.4; epsilon Hf(t) = 7.0-13.0] further demonstrate its derivation from subduction-modified asthenosphere mantle wedge. Integrated with coeval arc rocks reported in northern Tibet, this study suggests the possible existence of an early-stage, Late Devonian to Carboniferous Paleo-Tethyan arc belt across the northeastern Tibet, providing important evidence for the early evolution of the Paleo-Tethys Ocean. The intrusion has high magmatic oxygen fugacity (zircon Delta FMQ = 0.44-1.45, mean = 0.95 +/- 0.27) and elevated whole-rock Pd and Pt contents, which are comparable to global Au-rich porphyry Cu deposits. These features are distinct from the reduced and infertile magmas during the middle-late Permian, suggesting significant temporal heterogeneity in porphyry Cu-Au potential of Paleo-Tethyan arc magmas.

Post-collisional Cu-Au fertile porphyries, characterized by high K2O contents, elevated K2O/Na2O ratios, and adakite-like affinity, are widely distributed across the southeastern (SE) Tibetan Plateau. However, the petrogenesis of these economically significant porphyries remains debated. One prominent but not universally accepted model proposes that these fertile porphyries originated from hybrid magmas derived from both juvenile lower crust and metasomatized lithospheric mantle sources. To test this model, we conducted systematic dehydration partial melting experiments on a composite source material comprising juvenile lower crust-derived garnet amphibolite and metasomatized lithospheric mantle-derived lamprophyre. Experiments were performed at 2.0–2.5 GPa and 800–1050 °C, simulating magma generation at the lower crust-upper mantle boundary. The experimental melts span a compositional spectrum from intermediate to granitic. Crucially, melts generated at 2.2 GPa/950 °C and 2.5 GPa/(850–1000 °C) display geochemical signatures in agreement with those of fertile porphyries in the region. These include: (1) elevated SiO2, K2O and total alkalis (Na2O + K2O) contents and K2O/Na2O ratios, (2) enrichment in large-ion lithophile elements (LILEs) and light rare earth elements (LREEs), (3) pronounced negative Nb-Ta-Ti anomalies, and (4) adakite-like geochemical affinity. Moreover, these experimental melts contain high volatile (H2O-Cl-S) contents, consistent with estimates for natural fertile porphyries. Our results demonstrate that mixing of crustal and mantle components represents a viable petrogenetic model that can account for both the geochemical characteristics and volatile-rich nature of post-collisional fertile porphyry magmas in the SE Tibetan Plateau. This model offers important constraints on the origin of fertile porphyries in post-collisional settings.

Although great effort has been put into characterizing the sources of the Cenozoic ultrapotassic volcanic rocks in the southeastern Tibetan Plateau, insufficient attention has been paid to the magmatic processes in the magma plumbing systems of these rocks. We filled this gap by analyzing clinopyroxene (Cpx) phenocrysts of these rocks from the Wozhong area for major and trace elements and Sr isotopes. Based on textural and Mg# variations, Cpx phenocrysts were classified into five subtypes: type 1 has three zones (core, mantle, and rim) with decreasing Mg# outward (normal zoning); type 2 has two zones (core and rim) with normal zoning; type 3 has three zones with reverse zoning; type 4 has a homogeneous core and an oscillatory-zoned rim; and type 5 has fine oscillatory zoning. Estimated crystallization temperatures and pressures for the different types/ zones are variable at grain scale, suggesting that the crystallization of a single crystal took place at various depths. The prevalence of oscillatory and reverse zoning, parallel trace- element patterns, and overlapping chemical- isotopic compositions of the Cpx phenocrysts with relatively high Mg# (87-93) indicate that magma recharge and mixing took place in the magma plumbing system. All of the Cpx data together show two different compositional evolution trends that are consistent with fractional crystallization and melt-mush reactions induced by magma recharge in the magmatic plumbing system. Trace elements and Sr isotopes of the most primitive Cpx (Mg# 87-93) support the interpretation that the parental magma for the Wozhong ultrapotassic volcanic rocks was originally derived from a metasomatized mantle source.

Figures S1–S5 are the X-ray maps and compositional diagrams of whole-rock and clinopyroxene from Wozhong ultrapotassic rocks. Tables S1–S9 show the chemical and isotopic compositions of whole-rock and clinopyroxene from Wozhong ultrapotassic rocks, and the crustal contamination, melt-mush reaction, and metasomatized mantle source modelling results.

Effects of various Sm additions on microstructures and mechanical properties of a hot-extruded Mg-14Gd-0.5Zr alloy were studied in this work. The results indicate that Sm addition firstly clearly improves the strength and then decrease as the Sm content increases at both room temperature and high temperatures. The highest yield strength was obtained to be similar to 495 MPa and similar to 512 MPa under tension and compression, respectively, at room temperature with the Sm concentration of 1 wt% while those were to be 384 MPa and 248 MPa at 250 degrees C and 300 degrees C, respectively, with the Sm content of 0.5 wt%. Electron backscatter diffraction mappings reveal that Sm addition significantly promotes dynamic recrystallization, resulted in much more fine recrystallized grains and lower texture intensity. Furthermore, transmission electron microscopy observations show that Sm addition increases dynamic precipitates particularly in non-recrystallized regions, leading to relatively less aging precipitates during artificial peak-aging. Finally, discussion based on grain boundary strengthening and dispersion strengthening suggests that Sm addition improving the yield strength of the extruded Mg-14Gd-0.5Zr alloy is mainly attributed to more grain boundaries and dynamic precipitates at room temperature and high temperatures, respectively.

The Beiya porphyry‐skarn Au deposit is one of the largest gold deposits in China, temporally and spatially associated with Eocene intrusions in a post‐collisional setting in western Yunnan, China. In this study, we report new whole‐rock geochemistry, Sr‐Nd isotope, zircon U‐Pb geochronology and in situ zircon Hf‐O isotopes of quartz‐monzonite and biotite‐monzonite porphyries from the Beiya deposit. The porphyry‐skarn mineralization at the Beiya deposit is mainly associated with the quartz monzonite porphyry (35.8 ± 0.6 Ma), while the biotite‐monzonite porphyry (34.3 ± 0.5 Ma) represents a post‐mineralization intrusion crosscutting the main orebodies and the quartz‐monzonite porphyry. Both intrusions have high‐K and adakitic composition and are characterized by high Sr/Y ratios, high SiO 2 and Al 2 O 3 concentrations (SiO 2 = 69.80–73.86 wt%; Al 2 O 3 = 14.11–15.19 wt%), and low MgO, Cr, and Ni concentrations (MgO = 0.2–1.0 wt%; Cr = 1.76–11.13 ppm; Ni = 2.52–11.72 ppm). Their Sr‐Nd isotope compositions ( 87 Sr/ 86 Sr = 0.7066–0.7077; ε Nd ( t ) = –5.3 to –1.5) are consistent with the lower crustal‐derived amphibolite xenoliths ( 87 Sr/ 86 Sr = 0.7060–0.7100; ε Nd ( t ) = –10.0 to 0.0), indicating that they might be derived from a thickened juvenile lower crust beneath the Yangtze Craton. The biotite‐monzonite porphyry has lower zircon δ 18 O values of +5.3‰ to +6.8‰ and higher ε Hf ( t ) values of –2.3 to +5.5 than those of the quartz‐monzonite porphyry with δ 18 O values of +7.1‰ to +8.2‰ and ε H f ( t ) values of –3.8 to +1.5, implying that they were derived from different parts of the lower crust. High Ba/La and Pb/Ce ratios suggest that the quartz‐monzonite porphyry is derived from a volatiles‐rich reservoir. Relatively higher La/Yb, Sm/Yb and Dy/Yb ratios of the biotite‐monzonite porphyry indicate residual garnet in the source, indicating a deeper source than that of the quartz‐monzonite porphyry. The hydrous components should be represented by the amphibole‐rich lithologies, which has relatively shallower depth than that of the garnet‐bearing mafic thickened lower crust. Our data suggest that the mineralized quartz‐monzonite porphyry at the Beiya deposit is derived from partial melting of amphibole‐rich lithologies in the upper part of the thickened juvenile lower crust beneath the Yangtze Craton, while the post‐mineralization biotite‐monzonite porphyry is derived from the basal, and volatiles‐poor, part of the juvenile lower crust.

陆内环境斑岩型矿床的成矿金属与硫等物质主要来源于富原生硫化物且呈相对还原状态的角闪岩相下地壳的部分熔融,岩浆的高氧逸度和富水是成矿的关键,但还原性下地壳的熔融产物如何变成高氧逸度岩浆尚不十分明确.为此,本文对哀牢山-红河富碱斑岩带内与陆内成矿斑岩同时代的莴莊粗面玄武岩与谷装箐云煌岩开展了成岩物理化学条件研究.结果 显示,这类钾质-超钾质岩的岩浆具有较高的△FMQ值(+0.8～+4.3),这一特征很可能继承于经历古大洋俯冲改造的岩石圈地幔.幔源高氧逸度岩浆具备调节与改造下地壳熔融产物氧逸度的潜力.因此,源于古俯冲改造的岩石圈地幔且具有较高△FMQ(+2.7～ +4.3)的钾质-超钾质岩浆,可能是导致陆内斑岩成矿系统中斑岩岩浆具较高氧逸度的原因,这类钾质-超钾质岩浆与富硫化物的新生的下地壳来源的熔体的混合,可能是导致陆内斑岩成矿的关键.

A common perception is that oxidized magma is critical for the formation of a porphyry Cu +/- Mo +/- Au ore deposit We have used an ore-beating pluton (Tongchang) and an ore-barren pluton (Shilicun) in the western rim of the South China block to test this idea and to determine other important controls on ore genesis. Zircon U-Pb ages indicate that the Tongchang and Shilicun plutons were emplaced at 36.3 +/- 0.2 Ma and 35.2 +/- 0.4 Ma, respectively, broadly coinciding with strike-slip faulting in the region and continental collision that occurred similar to 300 km to the west. These two plutons are all characterized by significant light REE enrichments and pronounced negative Nb-Ta anomalies, similar to the bulk crust. Apatite separates from these two plutons all have elevated initial Sr-87/Sr-86 (Tongchang, 0.70690 to 0.70796; Shilicun, 0.70703 to 0.70726) and negative epsilon(Nd) (t) (Tongchang, -6.2 to -7.3; Shilicun, -4.5 to -5.8). The mean epsilon(Hf)(t) and delta O-18 of zircon from these plutons are -1.4 and 6.8 parts per thousand for Tongchang, and -0.3 and 6.5 parts per thousand for Shilicun. The Sr-Nd-Hf isotope compositions are all within the ranges of the Neoproterozoic mafic arc lower crust in the region. Whole-rock U-Nb-Ta systematics indicate that the Tongchang and Shilicun plutons originated from an amphibole-bearing source and a garnet-bearing source, respectively, implying a shallower and more H2O-rich mafic source for the former than the latter. Quartz trace element data indicate that the Tongchang pluton was emplaced at a shallower depth than the Shilicun pluton. Zircon Ce4+/Ce3+ and whole-rock V/Sc ratios, and apatite SO3 and MnO contents indicate that the parental magmas of both plutons are as oxidized as those of some porphyry Cu deposits in northern Chile, but the parental magma of the Tongchang pluton is less oxidized than that of the Shilicun pluton. Apatite Cl-F-OH systematics and higher abundant hydrous silicate minerals such as amphibole and biotite in the Tongchang pluton than the Shilicun pluton indicate that the parental magma of the Tongchang pluton has higher Cl and H2O content than that of the Shilicun pluton. Our results show that oxidized magma is important but this alone cannot make a porphyry Cu +/- Mo +/- Au ore deposit. High contents of H2O-Cl in magma and shallow depth of emplacement are also important. (C) 2019 Elsevier B.V. All rights reserved.

Generally, porphyry Cu deposits are associated with the comagmatic porphyry (or subvolcanic)-volcanic systems of high magmatic H2O-fO(2) conditions. The volcanic rocks, as the counterpart of the porphyries, thus can provide some significant insights into the fertility of the porphyries to some extent. For this reason, we have used the Lawu volcanic rocks and spatial-temporal closely-related porphyries in the newly discovered porphyry Cu prospects (e.g., Seli, Zongguo, Mamupu) in the southern segment of the Yulong intracontinental porphyry Cu belt to illustrate the relationship between the porphyries and volcanic rocks, petrogenesis of the volcanic rocks, and then to evaluate the ore potential of the porphyries based on the magmatic H2O-fO(2) conditions. Both the Lawu volcanic rocks and Seli-Zonguo-Mamupu porphyries are shoshonitic and metaluminous, and have similar REE patterns, and Sr-Nd-Hf isotopic compositions, which suggest a comagmatic relation between the volcanic rocks and porphyries. An episodic magmatism model is proposed to explain the slightly younger age (similar to 36-35 Ma) and less evolved nature of volcanic rocks than the porphyries. The Lawu volcanic rocks of mainly intermediate composition (SiO2 = 54.25-64.68 wt%) have high K2O (4.75-5.94 wt%) and high K2O/Na2O ratios (1.69-2.00), broadly similar to the coeval Yulong fertile granitic porphyries and the Nangqian mafic lavas. The (Sr-87/Sr-86)(i) and epsilon(Nd)(t) values, uniform zircon epsilon H-f(t) and delta O-18 values, and lack of inherited zircons of the Lawu volcanic rocks don't support their formation by mixing between the mantle-derived Nangqian mafic lavas and crustderived Yulong felsic porphyries or assimilation and fractional crystallization (AFC) of mafic magmas. They are characterized by high Ba/Th, Ba/La and listric-shaped normalized rare earth element profile with significantly negative Nb-Ta-Ti anomalies, and have high initial Sr-87/Sr-86 ratios (0.7071-0.7079) and low epsilon(Nd)(t) values (- 5.71 to - 3.05), and low zircon epsilon(Hf)(t) (-1.53 to 4.09) and clearly high delta O-18 values (6.67-8.42 parts per thousand), suggesting that, they were probably formed by fractional crystallization (FC) of mantle-derived mafic magmas and originated from mantle domains modified by significant amount of H2O-rich marine sediments of the Paleo-Tethyan oceanic slab. Magmatic H2O contents calculated from deepest-crystallized amphiboles indicate that, the Lawu volcanic rocks and Zongguo porphyries have initial magmatic H2O contents as high as the Yulong fertile porphyries and typical porphyry Cu systems worldwide (commonly > 4 wt% H2O). Magmatic fO(2) (Delta FMQ) of the Lawu volcanic rocks (0.6-1.3, ave. 0.9 +/- 0.1) and the Zongguo porphyries (0.9-1.7, ave. 1.4 +/- 0.2) are clearly lower than the fertile porphyries in the giant Yulong deposit (Delta FMQ = 1.6-3.3, ave. 2.3 +/- 0.5) and typical porphyry Cu deposits in the world (commonly Delta FMQ > 2). The slightly lower magmatic H2O contents and slightly higher magmatic fO(2) of the Zongguo porphyries than the Lawu volcanic rocks were ascribed to variable degassing during magmatic evolution. These suggest that, in spite of the high magmatic H2O contents, the comagmatic porphyries (at least the Zongguo porphyries) of the Lawu volcanic rocks in the southern segment of the Yulong porphyry Cu belt are unlikely to produce large-scale porphyry Cu mineralization like the giant Yulong deposit, due to the low magmatic fO(2) conditions.

S and Te-doped Cu2SnSe3 samples with chemical formula of Cu2SnSe3-xSx and Cu2SnSe3-xTex (x = 0.05, 0.10, 0.15, 0.20) are prepared, and the effect of S and Te-doping on thermoelectric properties is investigated. In all the samples, the Cu2SnSe3 phase is synthesized as the major product, and its lattice parameters decrease with S-doping but increase with Te-doping. EDS analysis confirms the incorporation of S and Te dopants in the Cu2SnSe3 phase, and reveals an element segregation in the Te-doped samples. S- and Te-doping decreases the electrical conductivity, enhance the Seebeck coefficient, and reduce the thermal conductivity. S-doping is effective to improve the ZT of Cu2SnSe3, and the Cu2SnSe3-xSx sample with x = 0.05 shows a ZT of 0.66 at 773 K, which is improved by more than 50% compared with that of the undoped sample. On the contrary, Te-doping leads to decreased ZT values owing to the significant reduction in electrical conductivity.

The fabrication of bulk thermoelectric materials usually involves multi-step processes with considerable time and energy consumption. Here we applied a direct and rapid way of gas pressure assisted combustion synthesis to produce thermoelectric materials. As an example, bulk samples of Cu2SnSe3 had been prepared and their thermoelectric properties were investigated. Thermal analysis indicated that the Cu2SnSe3 samples kept stable up to 850 K. The un-doped Cu2SnSe3 showed ZT of 0.51 at 773 K, and by doping with Ag and In the ZT could be much increased to 1.42 at 823 K. The gas pressure assisted combustion synthesis method might provide a rapid way to directly produce bulk thermoelectric materials.

Cu2SnSe3 is a kind of new thermoelectric material with low or no poisonous elements. It has low thermal conductivity and high conductivity. The doping of Cu2SnSe3 can greatly improve the thermoelectricity of Cu2SnSe3, which is expected to be applied near the middle temperature region. The relative density of Cu2SnSe3 bulk material prepared by direct combustion synthesis is over 96％, and the maximum thermoelectricity is 0.48. It is equivalent to the sample prepared by the traditional sintering process. The whole reaction process is completed in a few minutes, thus greatly simplifying the synthesis process. In order to further improve the thermoelectric properties of Cu2SnSe3 materials, the polycrystalline bulk materials were prepared by combustion synthesis method. The effects of doping on the thermoelectric properties were investigated by doping Cu2SnSe3 with S and Te. The results show that the Se doping of S and Te increases the Seebeck coefficient, decreases the thermal conductivity and electrical conductivity, and improves the thermoelectricity value. S doped Cu2SnSxSe3-x samples, when x=0.15 at 773 K temperature to obtain the maximum ZT value of 0.66. Te-doped Cu2SnTexSe3-x samples, the maximum ZT value was 0.40 at a temperature of 773 K at x = 0.05.

Cu2SnSe3 samples with different secondary phases are prepared from compositions of CuxSnSe3 (x=1.8–2.2) and Cu2SnySe3 (y=0.8–1.2), and their thermoelectric properties are investigated. For CuxSnSe3 samples, the secondary phase is SnSe2 for x=1.8 and 1.9 and SnSe for x=2.2, and nearly single-phase Cu2SnSe3 is obtained for x=2.0 and 2.1. For Cu2SnySe3 samples, the secondary phase is CuSe for y=0.8 and SnSe for x=1.1 and 1.2, and single-phase Cu2SnSe3 is produced for y=0.9 and 1.0. The lattice structure of synthesized Cu2SnSe3 depends on the x and y values, which is cubic for x≤2.0 or y≤1.0 and monoclinic for x>2.0 or y>1.0. Compared with the single-phase Cu2SnSe3 sample (ZT=0.42 at 773K), the samples with SnSe2 secondary phase show a greatly-enhanced ZT of 0.84 at 773K, which is likely the best result for un-doped Cu2SnSe3 up to now. The samples with SnSe secondary phase exhibit poor thermoelectric properties.

The influence of spark plasma sintering and high-pressure sintering technique on microstructure and magnetic properties of bulk alloys of MA Fe_~73.5 Cu_1Nb_3Si_~13.5 B_9 nanocrystalline powder were investigated. The results show that after milling for 70h, the single phase α-Fe nanocrystalline supersaturate solid solution powder with average grain size 9.5nm and bcc structure can be obtained. In DSC heating-up curve of MA powder, four exothermal peaks with different strength appear, which are corresponding to the structure relaxing process of distorted nanocrystalline supersaturate solid solution, crystallization process of trace amorphous phases and phase precipitation of supersaturate solid solution, respectively. The precipitation process of supersaturate solid solution is decided into two stages. Under the SPS sintering conditions at p=30MPa, t=5min, when sintering temperature is 1050℃, nanocrystalline (100nm) bulk alloy with relative density of 99% and main phase of α-Fe can be obtained, the magnetic properties of bulk alloy are: B_s=1.34T, H_c=7.34kA/m. Under the high-pressure sintering conditions of p=5.5GPa, t=5min, when P_w=1150W, single phase α-Fe nanocrystalline (21.4nm) bulk alloy with relative density of 99.1% can be obtained, the magnetic properties of which are: B_s=1.14T, H_c=8.22kA/m.