Search

The Yugusayi mafic-ultramafic complex, located in the Qimantagh area, East Kunlun orogenic belt, consists of harzburgite, olivine orthopyroxenite, hornblende pyroxenite, and hornblende gabbro, whic...

The ilvaite-bearing skarn associations in the Galinge skarn deposit were studied to determine their physicochemical formation conditions. A thermodynamic model setting pressure of 50 MPa (Pf=Ps=50 MPa) was set up to trace the skarn evolution. Petrographic evidence for replacement of garnet and magnetite by ilvaite in the early retrograde stage (Stage I) combined with thermodynamic modeling suggests that the alteration may have occurred at 400–470 °C under moderately high fO2 with ΔlgfO2(HM) ranges from −4 to −4.2. The model is based on a maximum pressure of 50 MPa calculated from magmatic amphibole geobarometer. The continuous breakdown of ilvaite with quartz to form ferro-actinolite and magnetite occur in the late retrograde stage (Stage II). The reactions occurred at 400-440°C under moderate fO2 (ΔlgfO2(HM): −4 to −4.4). In Stage III, the breakdown of ilvaite to form calcite, pyrite and ferroactinolite depends on XCO2 which can be estimated to be in a range of 0.005 to 0.05, and the reaction would occur at higher temperatures with increasing XCO2. Under these conditions, the breakdown occurs at 270–350 °C and low fO2 (ΔlgfO2(HM): up to −5.2). The thermodynamic model for continuous evolution from Stage I to Stage III completely records the conditions of the retrograde alteration, which is inconsistent with the thermobarometry imprints of fluid inclusions. Therefore, the petrography and phase relations of ilvaite are useful indicators of reaction conditions in various skarn deposit types.

Tin, tungsten, and rare metal are key strategic metals and are regarded as having closely relationship with highly evolved granites. However, excessive U accumulation with magmatic evolution, complex melt-fluid interaction, and late hydrothermal alteration make it difficult to obtain accurate age information from the highly evolved granitic system. The Xianghualing deposit, located in southern Hunan Province, China, is a giant Sn-Nd-Ta-polymetallic deposit with various types of mineralization spatially associated with the Laiziling and Jianfengling highly evolved granite plutons, and is an ideal target to investigate the magmatic-hydrothermal process of highly evolved magmas and related Sn-Nb-Ta-polymetallic mineralization. Previous studies have reported a relatively wide range of intrusion ages and multi-stage mineralization ranging from Triassic to Cretaceous. However, the timing and genetic link between magma emplacement and Sn-Nb-Ta-polymetallic mineralization remain controversial. Here we employ multiple dating methods, including SHRIMP zircon U-Pb analysis, LA-ICP-MS zircon and monazite U-Pb analysis, and molybdenite Re-Os dating analysis with a view to obtain a precise geochronological framework of the Xianghualing deposit. The SHRIMP zircon U-Pb data from the Laiziling protolithonite granite yielded a weighted 206Pb/238U age of 156.4±1.5Ma, whereas the LA-ICP-MS monazite U-Pb age for the Laiziling albite granite and the greisenized granite show 207Pb-corrected lower intercept 206Pb/238U ages of 155.5 ± 0.7 and 155.3 ± 0.5 Ma, respectively, which represent the emplacement ages of the Laiziling granite stock. Compared with the scattered SHRIMP and LA-ICP-MS zircon U-Pb age, monazite from the albite granite and greisenized granite yields more precise age information. Our study shows that monazite can be used as a robust tool for dating highly evolved granites. Molybdenite from the Laiziling pegmatite yields a Re-Os isochron age of 157.8±4.2Ma, which is consistent with the emplacement age of the Laiziling pluton. This result, integrated with previously reported metallogenic age, suggests a temporal and genetic link between the Laiziling granite and Sn-Nb-Ta polymetallic mineralization. Although multi-stage Sn-W metallogenic events have been identified in Nanling Region, it is suggested that the Xianghualing Sn-Nb-Ta mineralization formed during the Late Jurassic within a short duration coeval with the regional large-scale W-Sn mineralization at 160-150Ma.

Mineral inclusions, e.g., apatite, titanite, monazite, K-feldspar, are common in magmatic zircons. Although many studies mention that light rare earth element (LREE) contents of zircons could be compromised by an analytical artefact of the accidental sampling of mineral inclusions, how and to what degree these inclusions influence analysis of zircon composition is still not well constrained. Here we report U–Pb ages and trace element abundances for zircon crystals, where apatite and K-feldspar inclusions are observed, from diorite porphyry in the Weibao deposit, East Kunlun Mountains, Northern Tibetan Plateau. Although zircon morphological and chronological evidence consistently advocates a magmatic origin without undergoing significant hydrothermal alteration, 7 of 15 analytical spots show LREE-enriched patterns and low Ce/Ce* ratios which are comparable to those for published “hydrothermal” zircon. Quantitative modelling in this study manifests that these LREE-enriched patterns and low Ce/Ce* ratios can be achieved with only 0.1 to 2 vol% contamination from sub-micrometer apatite inclusions, which in practice are hard to monitor under the LA–ICP–MS (normally with large pit diameter and depth) and conventional microscopes. Titanite, monazite, xenotime, and allanite have similar roles to apatite, and LREE contents of zircon can be significantly elevated with only 0.05 vol% contamination from these inclusions. We therefore suggest that the widely used geochemical discrimination criteria for magmatic and hydrothermal zircon, e.g., (Sm/La)N vs. La and Ce/Ce* vs. (Sm/La)N diagrams and the degree of Ce anomalies, are ambiguous since they are extremely susceptible to contamination by mineral inclusions, and that within single samples only Ce4+/Ce3+ values calculated from zircons of low LREE values probably represent the oxidation state of magmas.

The Weibao Cu-Pb-Zn deposit is typical of skarn deposits in the Qimantagh metallogenic belt (QMB), East Kunlun Mountains, northern Tibetan Plateau. It comprises three ore blocks from west to east, known as Weixi, Main and Weidong. Mineralization in the Weibao deposit is intimately related to Late Triassic intrusions occurring at Weixi and Weidong, and orebodies are predominantly hosted by the Langyashan Formation (marine carbonate rocks), and to a lesser extent the Devonian volcanic rocks. Skarns from Weixi and Weidong are characterized by a high garnet/pyroxene ratio and diopside- and andradite-rich composition of pyroxenes and garnets, indicating a proximal, oxidized type. In contrast, skarn mineralogy of Main indicates a slightly reduced condition, typical of Pb-Zn skarn deposits. At least five hydrothermal mineralization stages can be identified and the microthermometric study indicates a general trend of cooling and dilution of the magmatic-hydrothermal fluids. Significant precipitation of Cu-Fe sulfides commenced from the fluid with the temperature of 340–448 °C and the salinity of 2.1–15.0 wt% NaCl equiv. Pb-Zn sulfides however mainly precipitated when the temperatures declined to

The Yemaquan polymetallic skarn deposit is located in the Qimantagh metallogenic belt (QMB), northern Qinghai-Tibet Plateau, China, with total ore resources of 82.7 million metric tons at 29.46 percent Fe, 0.40% Cu, 2.08% Pb and 1.77% Zn. In this study, new trace element composition of zircon in tandem with LA-ICP-MS U-Pb geochronology are provided for mineralized and barren intrusive rocks occurring within two magnetic anomaly areas (M1 and M13) at the Yemaquan deposit. These data, combined with whole rock major and trace element compositions, allow to constrain the geochronological framework and magmatic processes for different types of intrusive rocks within the district. The zircon U-Pb ages reveal that the polymetallic mineralization in the M1 and M13 anomaly areas results from two temporally distinct intrusive centers. Different to the M13 area where only the mineralized Devonian intrusions are recorded, both mineralized and barren intrusive rocks in the M1 area were emplaced in the Late Triassic. Whole rock major and trace elements indicate that both Triassic mineralized and barren rocks underwent significant fractional crystallization, with the Triassic barren rocks displaying much stronger plagioclase fractionation. In contrast, the limited whole rock silica range and high Eu/Eu* of Devonian mineralized intrusions indicate that they did not experience evident fractionation. Zircon trace elements show that the two mineralized groups at Yemaquan display similar, high zircon Ce/Ce* but distinguishable Eu/Eu* ratios, which suggest a consistent, high magmatic oxidation state but different water content. The magmatic water content of Devonian mineralized rocks higher than that of their Triassic counterparts probably suggests that the former are more Cu-fertile. This study confirms that both Devonian and Triassic intrusive activities are responsible for skarn Fe-Cu-Pb-Zn mineralization at the Yemaquan deposit. Meanwhile, in view of the general feature of Yemaquan in the context of skarn deposits from the QMB, we thus suggest that in future mineral exploration great attention should be paid to both the Triassic and Devonian intrusive rocks.

The Weibao copper–lead–zinc skarn deposit is located in the northern East Kunlun terrane, NW China. Igneous intrusions in this deposit consist of barren diorite porphyry (U–Pb zircon age of 232.0 ± 2.0 Ma) and ore-bearing quartz diorite and pyroxene diorite (U–Pb zircon ages of 223.3 ± 1.5 and 224.6 ± 2.9 Ma, respectively). Whole-rock major and trace element and accessory mineral (zircon and apatite) composition from these intrusions are studied to examine the different geochemical characteristics of ore-bearing and barren intrusions. Compared to the barren diorite porphyry, the ore-bearing intrusions have higher Ce4+/Ce3+ ratios of zircon and lower Mn contents of apatite, indicating higher oxidation state. Besides, apatite from the ore-bearing intrusions shows higher Cl contents and lower F/Cl ratios. These characteristics collectively suggest the higher productivity of ore-bearing quartz diorite and pyroxene diorite. When compared with ore-bearing intrusions from global porphyry Cu deposits, those from Cu–Pb–Zn skarn deposits display lower Ce4+/Ce3+ and EuN/EuN* ratios of zircon and lower Cl and higher F/Cl ratios of apatite. We conclude that these differences reflect a general geochemical feature, and that zircon and apatite composition is a sensitive tool to infer economic potential of magmas and the resulting mineralization types in intrusion-related exploration targets.

The Xingluokeng deposit is the largest tungsten deposit discovered in the Wuyi metallogenic belt, with 30.43 Mt WO3 reserves averaging at 0.23%. The main orebody mainly occurs in an altered granitic stock, comprising veinlet-disseminated and vein-type scheelite and wolframite mineralization. A comprehensive study of field investigations with whole-rock and in-situ geochemical and isotopic compositions was conducted on different intrusive phases of the Xingluokeng ore-bearing granitic stock, aiming to constrain the petrogenesis and its genetic link to W mineralization. The Xingluokeng stock is mainly composed of the porphyritic biotite granite (G1) as the upper part of the stock, intruded by the medium- to fine-grained biotite granite (G2) in the deep. Petrographic observations suggest that the stock experienced intense fractional crystallization as well as assimilation of country rocks close to stock margins. Zircon U − Pb geochronology and trace element analyses indicate that G1 and G2 were emplaced coevally at ~152 Ma at a relatively lower oxygen fugacity condition (Ce4+/Ce3+ = 44 ± 18 for G1, and 104 ± 41 for G2). Ti-in-zircon thermometer and AlT-in-biotite geobarometer reveal average crystallization temperature and depth at 762 ℃−740 ℃ and 7.3–7.0 km, respectively. Geochemically, obvious negative correlation between SiO2 and P2O5 and low A/CNK values (mostly

The Baiganhu W–Sn orefield in the southeastern Xinjiang Uygur Autonomous Region is associated with Caledonian S-type syenogranites and metasediments of the Paleoproterozoic Jinshuikou Group. Four types of garnets have been identified in the orefield using petrographic and major and trace element data. Grt-I garnets are generally present as inclusions within magmatic quartz in the syenogranites, with end-member formulas of Sps45–53Alm46–53Adr0–1Grs0–1Prp0–1 and rare earth element (REE) patterns that are enriched in heavy REE (HREE) and contain strong negative Eu anomalies. Grt-II garnets are associated with tourmaline and quartz and occur in interstices between feldspars within the syenogranites. In general, the Grt-II garnets have end-member formulae (Sps64–70Alm29–34Adr0–1Grs0–2Prp0) and REE patterns that are similar to the Grt-I garnets although they are more spessartine-rich and contain higher concentrations of HREE. Grt-III garnets coexist with clinopyroxenes and Mo-rich scheelites within skarns developed along the syenogranite and marble contact. Their compositions are Adr62–88Grs1–18Sps3–12Alm0–8Pyr0 and they have relatively flat REE patterns with no negative Eu anomalies. Grt-IV garnets are present as massive aggregates that are often cross-cut by Mo-poor scheelite-bearing calcite veins. Their end-member formulas are Adr4–22Grs62–73Sps5–16Alm2–10Pyr0 and they have slightly domed REE patterns without negative Eu anomalies. Both Grt-III and Grt-IV garnets contain lower concentrations of the HREE (2–3 and 4–32 ppm, respectively) than Grt-I and Grt-II garnets (682–1352 ppm with Y = 1558–2159 ppm, and 6051–12831 ppm with Y = 9663–13333 ppm, respectively). The occurrences, mineral assemblages, major element compositions, and REE patterns of the Grt-I and Grt-II garnets suggest they have magmatic origin and crystallized at relatively low temperatures and pressures, whereas the Grt-III and Grt-IV garnets have hydrothermal origin. The association of magmatic garnet (Grt-II) with tourmaline suggests that boron in S-type magmas has an important role in the formation of W–Sn mineralization during magmatic and subsequent hydrothermal processes. All four types of garnets contain low concentrations of W (⩽1.64 ppm) and Mo (

The Weibao copper–lead–zinc deposit, located in the eastern part of the Qimantagh area, East Kunlun Orogenic Belt (EKOB), consists of three skarn ore blocks known as Weixi, Main and Weidong from west to east. The mineralization within the Weibao Cu–Pb–Zn deposit is hosted by the Mesoproterozoic Langyashan Formation. In this study, we describe for the first time basaltic lavas that intruded into this host sequence and chronological, isotopic, major and trace element data of these volcanic rocks are presented here to constrain their eruption age as well as the tectonic setting. Two basaltic lava samples yield sensitive, high-resolution ion-microprobe (SHRIMP) U–Pb zircon ages of 393.0 ± 5.5 Ma–392.0 ± 5.0 Ma, indicating that volcanic rocks in the Weibao deposit erupted in Middle Devonian. The majority of the volcanic rocks have compositions characterized by high potassium, light rare earth element (LREE)-enriched patterns in chondrite-normalized rare earth elements (REE) diagrams, and evident enrichment of Rb, Ba and K and depletion of Th, U, Nb and Ta contents in primitive mantle-normalized patterns, although the degrees of enrichment and depletion are variable. These characteristics of major and trace element data highlight a hornblende-dominated fractionation during ascent of magmas. The eHf(T) values of zircons are relatively scattered and slightly enriched, ranging from −2.6 to +7.5. Modelling the features of the major, trace and isotopic element data indicates a hybrid origin involving combined depleted mantle (and hence asthenospheric mantle) and melts and/or fluids inherited from an early subduction event. Besides, these geochronological and geochemical data, together with previously published data in the EKOB, suggest that the Weibao basaltic lavas formed in a post-collisional setting, and that the Qimantagh area underwent strong interactions between mantle and crust in Early Paleozoic–Middle Devonian.

The recent discovery of numerous large porphyry Cu deposits in the southern Qinghai-Tibet Plateau shows that porphyry Cu deposits can be hosted in magmatic suites in collisional settings. However, in contrast, only a few small porphyry Cu deposits have so far been discovered in association with collision-related granitoids in the northern Qinghai-Tibet Plateau. This raises questions about the origin of collision-related magmas and their mineralization potential. In this contribution, we comprehensively synthesize whole-rock geochemical and isotopic data on collision-related intrusions from the Qimantagh Metallogenic Belt in the northern Qinghai-Tibet Plateau, which hosts many skarn polymetallic deposits but only a few, small porphyry Cu-Mo deposits. This, combined with newly obtained zircon trace element data, provides a high-quality database that can yield insights on the nature and origin of the magmatic suites as well as their fertility in terms of Cu mineralization. Two volumetrically dominant intrusive suites are identified in the Qimantagh Metallogenic Belt: 435-370 Ma granitoids (Suite I) and 245-196 Ma granitoids (Suite II). They formed during syn- to post-collisional stages of the Caledonian and Hercynian-Indosinian Orogenies, respectively. In contrast, arc magmatic rocks are relatively scarce. Both Suites I and II are characterized by low zircon Ce/Ce* and Eu/Eu* values, low whole-rock Sr/Y and Eu/Eu* values with arc-like features (e.g., depletion of Nb and Ta). Furthermore, both suites display some evolved Sr-Nd-Hf isotopic values (e.g., eNdi = -8.1 to 0.1), with the majority of samples characterized by Paleo- to Meso-Proterozoic two-stage Nd and Hf model ages. These features suggest that the parental magmas of the two suites were probably derived from subduction fluid-modified mantle sources which underwent significant crustal AFC processes during magma ascent. The relative scarcity of arc magmatic rocks and the prevalence of collisional magmatism during the Caledonian and Hercynian-Indosinian Orogenies in the Qimantagh Metallogenic Belt can be explained by pre-collisional, flat-slab subduction and subsequent slab breakoff during collision, the later triggering asthenosphere upwelling and extensive magmatism in collisional settings. Compared to fertile plutons in some large porphyry Cu deposits worldwide, especially those in the Gangdese Metallogenic Belt, the two suites in the Qimantagh Metallogenic Belt have low magmatic oxidation states and low water content which inhibited the formation of large porphyry Cu deposits. Thus, skarn polymetallic deposits (probably as well as small porphyry Cu-Mo deposits) rather than large porphyry Cu deposits should be targeted during future mineral exploration in the northern Qinghai-Tibet Plateau, since such deposits do not necessarily need a parental magma with high oxidation state and water content.

A granite-related scheelite deposit has been recently discovered in the Wuyi metallogenic belt of southeast China. The veinlet–disseminated scheelite occurs mainly in the inner and outer contact zones of the porphyritic biotite granite, spatially associated with potassic feldspathization and silicification. Re–Os dating of molybdenite intergrowths with scheelite yield a well-constrained isochron age of 170.4 ± 1.2 Ma, coeval with the LA–MC–ICP–MS concordant zircon age of porphyritic biotite granite (167.6 ± 2.2 Ma), indicating that the Lunwei W deposit was formed in the Middle Jurassic (~170 Ma). We identify three stages of ore formation (from early to late): (I) the quartz–K-feldspar–scheelite stage; (II) the quartz–polymetallic sulfide stage; and (III) the quartz–carbonate stage. Based on petrographic observations and microthermometric criteria, the fluid inclusions in the scheelite and quartz are determined to be mainly aqueous two-phase (liquid-rich and gas-rich) fluid inclusions, with minor gas-pure and CO2-bearing fluid inclusions. Ore-forming fluids in the Lunwei W deposit show a successive decrease in temperature and salinity from Stage I to Stage III. The homogenization temperature decreases from an average of 299 °C in Stage I, through 251 °C in Stage II, to 212 °C in Stage III, with a corresponding change in salinity from an average of 5.8 wt.%, through 5.2 wt.%, to 3.4 wt.%. The ore-forming fluids have intermediate to low temperatures and low salinities, belonging to the H2O–NaCl ± CO2 system. The δ18OH2O values vary from 1.8‰ to 3.3‰, and the δDV-SMOW values vary from –66‰ to –76‰, suggesting that the ore-forming fluid was primarily of magmatic water mixed with various amounts of meteoric water. Sulfur isotope compositions of sulfides (δ34S ranging from –1.1‰ to +2.4‰) and Re contents in molybdenite (1.45–19.25 µg/g, mean of 8.97 µg/g) indicate that the ore-forming materials originated mainly in the crust. The primary mechanism for mineral deposition in the Lunwei W deposit was a decrease in temperature and the mixing of magmatic and meteoric water. The Lunwei deposit can be classified as a porphyry-type scheelite deposit and is a product of widespread tungsten mineralization in South China. We summarize the geological characteristics of typical W deposits (the Xingluokeng, Shangfang, and Lunwei deposits) in the Wuyi metallogenic belt and suggest that porphyry and skarn scheelite deposits should be considered the principal exploration targets in this area.

The newly discovered large-scale Baiganhu W–Sn orefield, consisting of the Kekekaerde, Baiganhu, Bashierxi, and Awaer deposits, is located in Ruoqiang County, southeastern Xinjiang, China. These deposits comprise mainly three types of W–Sn mineralization: early-stage skarn-type, middle-stage greisen-type, and late-stage quartz-vein-type. In this study, we classified seven major vertical zones on the basis of petrographic characteristics, roughly from the bottom of the parental granitic intrusions upward, as (A) fresh syenogranite, (B) argillic alteration, (C) muscovite-dominated greisenization, (D) tourmaline-dominated greisenization, (E) marginal facies (including K-feldspar pegmatite and fine-grained granite), (F) aplitic apophysis, and (G1) skarn or (G2) infilled silification zones. According to the alteration–mineralization assemblages and cross-cutting relationships, five stages of mineralization are recognized in the orefield (I, skarn stage; II, greisen stage; III, quartz vein stage; IV, argillic alteration stage; and V, supergene stage), and reverse alteration zonation in the altered intrusion is also observed. The W–Sn deposits are spatially associated with syenogranite, which is part of the Caledonian Bashierxi magmatic series. Laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) zircon U–Pb dating of the syenogranite yields a weighted mean 206 Pb/ 238 U age of 413.6 ± 2.4 Ma (MSWD = 0.36, n = 30). Hydrothermal muscovite from three samples associated with W–Sn mineralization yields plateau 40 Ar/ 39 Ar ages of 411.7 ± 2.6 Ma (MSWD = 0.21), 412.8 ± 2.4 Ma (MSWD = 0.22), and 413.8 ± 2.6 Ma (MSWD = 0.22), which is consistent with the zircon U–Pb age, thus indicating a temporal link between the emplacement of the syenogranite and the W–Sn mineralization. Our age data and previously published ages, along with geochemical data, for the granitoids in the Bashierxi magmatic series show a nearly contemporaneous evolution of A- and S-type granites, which were emplaced in a post-orogenic setting at ca. 432–413 Ma. As compared with the A-type granites, the syenogranites with S-type affinities probably resulted from a lower degree of partial melting of metagreywackes, which was more likely to be enriched in the ore-forming elements W and Sn, as well as volatiles such as B and H 2 O. In addition, the syenogranites exhibit low oxidation states and underwent high degrees of factional crystallization, both of which favor post-magmatic W–Sn mineralization. We suggest that more attention should be given to buried syenogranites of S-type affinities during mineral exploration in this area, and that the proposed model of a vertical alteration zoning can act as a guide to the targeting of similar ore systems.

The Saishitang Cu deposit, located on the eastern area of the Eastern Kunlun Orogenic Belt (EKOB), and on the northern margin of the Tibetan Plateau, is one of the most important copper deposits in Qinghai Province, China. Skarn and Cu orebodies mainly occur as stratoids or lenses along the contact zone between the quartz diorite and Lower to Middle Triassic metamorphosed tuff and marble. In this study, we use new zircon U–Pb ages, molybdenite Re–Os ages, granitoid geochemical compositions, and zircon Hf isotope data to constrain the ore genesis and the tectonic setting of the Saishitang Cu deposit. The quartz diorite is composed of inner medium- to fine-grained quartz diorite phase and an outer porphyritic quartz diorite phase. U–Pb dating of zircons by laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) yield ages of 222.7 ± 2.3 Ma and 222.6 ± 2.4 Ma for the inner and outer phase of quartz diorite, respectively. Molybdenite separated from ore-bearing quartz veins yields a Re–Os isochron age of 223.4 ± 1.5 Ma, indicating a close temporal link between magmatism and mineralization. Geochemically, the quartz diorite shows high contents of SiO 2 (59.63–68.21 wt.%), Al 2 O 3 (15.57–18.13 wt.%) and Na 2 O (3.07–3.56 wt.%), with A/CNK values between 0.90 and 1.01 and Mg# between 46 and 52, classified as the calc-alkaline I-type granite. The trace element patterns are characterized by high LREE (LREE/HREE = 7.36–13.03), weak negative Eu anomalies (δEu = 0.69–0.86), relative enrichment of Rb, Th, K, and Pb, and depletion of Nb, Ta, P, and Ti. The quartz diorite has variable e Hf (t) values (− 2.5 to 4.87) and Mesoproterozoic two-stage model ages (997 to 1387 Ma). Based on petrological and geochemical features, we infer that the quartz diorite is derived from the partial melting of thickened lower crust with an additional input of mantle components. According to the geological, geochemical, and mineralogical features, we propose that the Saishitang Cu deposit is a skarn deposit with minor porphyry-type mineralization and the porphyry–skarn mineral system is related to the crust–mantle interaction. Based on the tectonic evolution of the Paleo-Tethys Ocean during the Late Triassic, we infer that the intrusions and associated Cu mineralization were related to regional extension of the EKOB in a post-collision environment. The results also show that most porphyry–skarn Cu deposits in the EKOB have similar mineralization ages (240–220 Ma) and the Late Triassic granitoids in the EKOB present significant potential for the prospecting of porphyry–skarn Cu deposits.

The post-collisional magmatism of Qiman Tagh is characterized by the intrusion of voluminous intermediate to felsic granitoids, including syenogranite, monzogranite, granodiorite, tonalite and diorite. The granitoids can be divided into two magmatic suites: Calc-alkaline (CA) and alkaline (Alk), which were emplaced from ~ 236 Ma to ~ 204 Ma. The CA suite contains metaluminous granodiorites and monzogranites. Typical Qiman Tagh CA granodiorites show moderately fractionated REE patterns ((La/Yb)N = 4.35–25.11) with significant negative Eu anomalies (Eu/Eu* = 0.54–1.34), and the primitive mantle-normalized spidergrams show strong depletion of Nb and Sr. The Qiman Tagh CA monzogranites show similar fractionated REE patterns ((La/Yb)N = 2.70–13.5) with less prominent negative Eu anomalies, and the chondrite-normalized spidergrams show strongly depleted Ba, Nb and Sr. The Alk suite, including syenogranite, is highly potassic (K2O/Na2O = 1.09–3.56) and peraluminous (A/CNK = 0.91–1.06). Compared to typical Qiman Tagh CA granodiorites, the Qiman Tagh Alk granitoids can be distinguished by their higher Rb, Nb, Ga/Al, FeO*/MgO, Y/Sr and Rb/Sr, as well as their lower Mg#, MgO, CaO, Al2O3, Sr, Co, V, Eu/Eu*, Ba/Nb, La/Nb, Ba/La and Ce/Nb. The Qiman Tagh CA rocks were most likely to be derived from the partial melting of garnet-amphibolite-facies rocks in the lower crust, leaving behind anhydrous granulite-facies rocks with plagioclase and garnet in the residue. The Alk rocks may have formed by the continued partial melting of granulite-facies rocks at elevated temperatures (> 830 °C).

The large Huamei'ao tungsten deposit, with total WO 3 reserves of 67,400 tons at an average grade of 1.334% WO 3 , is located in the convergent zone of the eastern Nanling E–W-trending tectono-magmatic belt and the western Wuyishan NNE–SSW-trending tectono-magmatic belt in southern Jiangxi Province, China. The tungsten mineralization in this deposit is mainly found in quartz–wolframite veins, with most orebodies distributed at the outer contact zone between concealed Late Jurassic granitic stocks and Sinian weakly metamorphosed sandstones and phyllites. Zircons collected from medium- to fine-grained biotite granite in a diamond drill hole at a sea level of ca. − 10 m yield a crystallization age of 159.9 (± 1.2) Ma through laser ablation–multicollector–inductively coupled plasma–mass spectrometry (LA–MC–ICP–MS) U–Pb dating. Molybdenite and muscovite that were both separated from quartz–wolframite veins yield a Re–Os isochron age of 158.5 (± 3.3) Ma and an 40 Ar– 39 Ar weighted plateau age of 157.9 (± 1.1) Ma, respectively. These dates, obtained via three independent geochronological techniques, constrain the ore-forming age of the Huamei'ao deposit and link the genesis of the ore and the underlying granite. Analyses of available high-precision zircon U–Pb, molybdenite Re–Os and muscovite 40 Ar– 39 Ar radiometric ages of major W–Sn deposits in southern Jiangxi Province indicate that there is no significant time interval between W–Sn mineralization and its intimately associated parent granite emplacement (interval of 0–6 Ma). These deposits formed over three intervals during the Mesozoic (240–210, 170–150, and 130–90 Ma), with large-scale W–Sn mineralization occurring mainly between 160 and 150 Ma. The majority of W–Sn deposits in this region are located in southern Jiangxi and southern Hunan provinces.

The metamorphosed sedimentary type of iron deposits (BIF) is the most important type of iron deposits in the world, and super-large iron ore clusters of this type include the Quadrilatero Ferrifero district and Carajas in Brazil, Hamersley in Australia, Kursk in Russia, Central Province of India and Anshan-Benxi in China. Subordinated types of iron deposits are magmatic, volcanic-hosted and sedimentary ones. This paper briefly introduces the geological characteristics of major super-large iron ore clusters in the world. The proven reserves of iron ores in China are relatively abundant, but they are mainly low-grade ores. Moreover, a considerate part of iron ores are difficult to utilize for their difficult ore dressing, deep burial or other reasons. Iron ore deposits are relatively concentrated in 11 metallogenic provinces (belts), such as the Anshan-Benxi, eastern Hebei, Xichang-Central Yunnan Province and middle-lower reaches of Yangtze River. The main minerogenetic epoches vary widely from the Archean to Quaternary, and are mainly the Late Archean to Middle Proterozoic, Variscan, and Yanshanian periods. The main 7 genetic types of iron deposits in China are metamorphosed sedimentary type (BIF), magmatic type, volcanic-hosted type, skarn type, hydrothermal type, sedimentary type and weathered leaching type. The iron-rich ores occur predominantly in the skarn and marine volcanic-hosted iron deposits, locally in the metamorphosed sedimentary type (BIF) as hydrothermal reformation products. The theory of minerogenetic series of mineral deposits and minerogenic models has applied in investigation and prospecting of iron ore deposits. A combination of deep analyses of aeromagnetic anomalies and geomagnetic anomalies, with gravity anomalies are an effective method to seeking large and deep-buried iron deposits. China has a relatively great ore-searching potential of iron ores, especially for metamorphosed sedimentary, skarn, and marine volcanic-hosted iron deposits. For the lower guarantee degree of iron and steel industry, China should give a trading and open the foreign mining markets.

The Yinkeng orefield in Yudu County, Jiangxi Province, SE China, is a zone of concentrated Au-Ag-Pb-Zn-Cu-Mn polymetallic ores. Based on summing up basic geology and ore geology of the orefield, the polymetallic deposits in the orefield have been divided into seven major substyles according to their occurring positions and control factors. The ore-forming fluid inclusion styles in the orefield include those of two-phase fluid, liquid CO2-bearing three-phase and daughter mineral-bearing multi-phase. The homogenization temperatures range from 382° to 122°C, falling into five clusters of 370° to 390°, 300° to 360°, 230° to 300°, 210° to 290° and 120° to 200°, and the clusters of 300° to 360°, 230° to 300° and 120° to 200° are three major mineralization stages, with fluid salinity peaks from 4.14% to 7.31%, 2.07% to 7.31% and 0.53% to 3.90%, respectively. The ore-forming fluids are mainly type of NaCl-H2O with medium to high density (0.74–1.02 g/cm3), or CO2-bearing NaCl-H2O with medium to low density (0.18–0.79 g/cm3). The fluid salinity and density both show a decline tendency with decreasing temperature. According to the measurement and calculation of H- and O-isotopic compositions in the quartz of the quartz-sulfide veins, δDV-SMOW of the ore-forming fluid is from –84‰ to –54‰, and δ18OV-SMOW of that is from 6.75‰ to 9.21‰, indicating a magmatic fluid. The δ34SV-SDT of sulfides in the ores fall into two groups, one is from –4.4‰ to 2.2‰ with average of –1.42‰, and the other from 18.8‰ to 21.6‰ with average of 19.8‰. The S-isotopic data shows one peak at –4.4‰ to 2.2‰ (meaning –1.42‰) suggesting a simple magmatic sulfur source. The ore Pb-isotopic ratios are 206Pb/204Pb from 17.817 to 17.983, 207Pb/204Pb from 15.470 to 15.620 and 208Pb/204Pb from 38.072 to 38.481, indicating characteristics of mantle-derived lead. The data show that the major ore deposits in the orefield have a magmatic-hydrothermal genesis and that the SHRIMP zircon age of the granodiorite porphyry, closely related to the mineralization, is 151.2±4.2 Ma (MSWD = 1.3), which can represent the formation ages of the ores and intrusion rocks. The study aids understanding of the ore-forming processes of the major metallic ore deposits in the orefield.

The title compounds (III) are conveniently obtained by tandem conjugate addition-cyclization reaction of acetylenic ketones and hydroxylamine hydrochloride.

The southern Jiangxi Province is a major part of the Nanling W–Sn metallogenic province of southern China, where all W–Sn ore deposits are temporally and spatially related to Mesozoic granitic intrusions. The Tianmenshan–Hongtaoling orefield is a recently explored territory endowed by several styles of W–Sn mineralization. The orefield comprises three composite granitic plutons: Tianmenshan, Hongtaoling and Zhangtiantang associated with several tens of W–Sn-polymetallic ore deposits (Maoping, Baxiannao, Niuling, Zhangdou, Yaolanzhai and others) along their contacts. In this study, four new SHRIMP zircon U–Pb ages were determined for three composite granitic plutons, and 33 molybdenite samples from five W–Sn deposits were analysed by ICP-MS Re–Os isotopic method. SHRIMP zircon U–Pb ages for both medium to coarse-gained biotite granite and porphyritic biotite monzogranite from the Tianmenshan composite pluton are 157.2 ± 2.2 Ma and 151.8 ± 2.9 Ma, respectively. Molybdenite Re–Os isochron ages for the related Baxiannao fracture-controlled tungsten deposits are 157.9 ± 1.5 Ma. Maoping greisens-type tungsten deposits were emplaced at 155.3 ± 2.8 Ma and the Maoping wolframite–quartz veins at 150.2 ± 2.8 Ma, respectively. The SHRIMP U–Pb age of zircons from the Hongtaoling biotite granite is 151.4 ± 3.1 Ma whereas the molybdenite Re–Os isochron ages of the genetically related Niuling endocontact tungsten quartz veins and Zhangdou exocontact tungsten quartz veins are 154.9 ± 4.1 to 154.6 ± 9.7 Ma and 149.1 ± 7.1 Ma, respectively. The SHRIMP zircon U–Pb age of the Zhangtiantang fine-grained muscovite granite is 156.9 ± 1.7 Ma, whereas the molybdenite Re–Os isochron age for the related Yaolanzhai greisens-type tungsten deposit is 155.8 ± 2.8 Ma. These new age data, combined with those available from the literature, indicate that the ages of W–Sn ores and related granites are Late Jurassic with a peak at 150 to 160 Ma, which corresponds to the widespread Mesozoic metallogenic event in southern China. Molybdenites from this group of tungsten deposits have quite low Re contents (29.1 to 2608 ppb), suggesting continental crustal provenance of the ore metals.

Highly functionalized tetrasubstituted allylic alcohols were prepared conveniently by CuI-catalyzed tandem carbomagnesiation/carbonyl addition of Grignard reagents with acetylenic ketones. The obtained allylic alcohols can be further transformed to polysubstituted indenes by intramolecular cyclization.

(Z)-Tetrasubstituted allylic alcohols bearing sulfonyl group were synthesized regio- and stereoselectively by alkylzincation of acetylenic sulfone followed by addition to aldehyde.

The Tuolugou cobalt–(gold) deposit, in the northeastern margin of the Qinghai–Tibetan plateau and central part of the eastern Kunlun orogenic belt, is the most recently discovered, large, cobalt–(gold) discovery in Qinghai Province, NW China. Exploration to date has identified a cobalt resource of greater than 20,000 t Co, with significant potential for expansion. Mineralization is largely confined to an E-W-striking volcano-sedimentary sequence consisting of four lithological units that underwent extensive greenschist-facies metamorphism and deformation. All orebodies occur in stratiform or lenticular bodies within quartz–albitite and sericite–quartz schists, and are concordant with lithological contacts. The ores contain various amounts of pyrite, the dominant ore mineral, and display massive (> 80% pyrite), banded (30 to 50% pyrite), and disseminated ( Re–Os dating shows that pyrite from different ore types has very low Re and Os concentrations in the range of 0.122–8.988 ppb and 0.003–0.054 ppb, respectively. Isotope data on seven pyrite samples yield an isochron age of 429 ± 29 Ma (2σ) with an initial 187Os/188Os ratio of 0 ± 2 (mean square weighted deviates = 7.9) on the 187Re/188Os-187Os/188Os plot, which are close to the age of the host strata, suggesting that primary cobalt mineralization in the Tuolugou deposit may have formed from syngenetic–exhalative processes. In addition, our results not only provide new evidence for plate rifting and mineralization taking place during the Early Silurian in the eastern Kunlun orogenic belt, but also suggest that the age of the regionally widespread Nachitai Group is early Paleozoic.

Holocene volcanoes in the Jingpohu region are situated in the “Crater Forest” and “Frog Pool” areas along the northwest side of Jingpohu Lake, northeastern China. Dating of three charcoal samples from the first and second volcanic cycles shows that the ages of the first and second cycles are 3430~3490 and 2470 years respectively. The lavas from the Jingpohu area consist of basanites (BSN), alkali olivine basalts (AOB) and tephrites (TP). Crystal fractionation models are consistent with the generation of AOB and TP from a basanitic parent. Minor fractionation of olivine, augite, magnetite and Cr-spinel is required to produce AOB compositions whereas the generation of TP requires extensive fractionation of kaersutite, phlogopite and anorthoclase with minor olivine, augite, magnetite and leucite. The presence of kaersutite, phlogopite and anorthoclase megacrysts and mantle xenoliths suggest a fractionation history occurring at high pressure in the mantle. Although all basaltic rocks contain many granitic xenoliths, their geochemical characteristics show that they have not undergone any contamination of upper crust en route to the surface, but some alkali basalts were suffered from the contamination of lower crust. Relatively unradiogenic isotope ratio (compared with Bulk Earth), steep chondrite-normalized REE patterns and strong incompatible element enriched patterns suggest that the magmas are derived from a mixture of an incompatible element depleted anhydrous lherzolite asthenospheric mantle source and an enriched, amphibole-phologite(apatite-)bearing lherzolite continental lithospheric mantle source. We propose that the basanites are the products of very low degree partial melts (

Being a part of the Paleo-Tethys Ocean, closing of the Buqingshan-Anyemaqen oceanic basin left a rich geologic record in the East Kunlun Orogenic Belt. The genesis and tectonic setting of the granites including quartz monzodiorite, granodiorite and mozogranite is discussed in light of the geochemical and U–Pb chronological data obtained. U–Pb dating studies on zircon from the quartz monzodiorite and monzogranite of the research area yielded ages of 220.11 ± 0.49 Ma ((Mean Square Weighted Deviates) MSWD = 0.046) and 223.33 ± 0.54 Ma (MSWD = 0.14), respectively, by Laser Ablation Multiple Collector Inductively Coupled Plasma Mass Spectrometry (LA–MC–ICP–MS) method. According to sedimentological and structural investigations, the Paleo-Tethys Ocean in the Qimantag region began to close at about 235 Ma, and completely disapperared at about 220 Ma. The three types of granites in this study are considered to intrude the syn- to post-collisional stages. The quartz monzodiorite and granodiorite belong to the I-type granite whereas the monzogranite is of the S-type granite. These two types of granites were formed by different ways of partial melting: first, partial melting of the lower crust took place as a result of asthenosphere upwelling triggered by break-up of the leading edge or tearing of the descending oceanic slab. Subsequently partial melting of the middle–lower crust was caused by the underplating of basaltic magma formed by partial melting of the mantle wedge fluxed by fluids liberated by the oceanic slab dehydration. The magma responsible for the formation of S-type granites appears to have originated from partial melting of the upper crustal material at a shallower level with a clear signature of continental crust.

Through studying geo-geochemical characteristics and determining Sm-Nd and Rb-Sr isotopical ages in the Kanggur magnetite-chlorite formation gold deposit, some conclusions can be achieved: Sm-Nd isochron age is (290.4 ± 7)Ma, Rb-Sr isochron age is (282.3 ± 5)Ma, mineralization is Late Hercynian and the formation of this gold deposit is related to the macroscopic Huangshan-Qiugemingtashi ductile shear zone which is produced as a result of collision between the Tarim plate and the Junggar plate.

The title compounds (III) are conveniently obtained by tandem conjugate addition-cyclization reaction of acetylenic ketones and hydroxylamine hydrochloride.

A variety of polyfunctionalized allylic alcohols (III), (VII) is obtained by the title reaction.

Acetylenic sulfones (I) undergo a CuI-catalyzed carbozincation reaction with dimethyl- or diethylzinc to give alkenylzinc intermediates.

Xenoliths within augite diorite at the Chaihalanzi gold deposit are grouped into mafic and amphibolite compositions; the mafic ones have experienced granulite metamorphism. Geochemistry, P-T conditions and isotopes of the mafic xenoliths indicate that they were derived from the lower continental crust and resulted from magmatic underplating during the early Mesozoic. The similarity in geochemistry and isotopic composition between host rock and mafic granulite xenoliths indicate that both were products that evolved from the same magmatic sources. Underplating is considered to have played an important role in the formation and migration of ore-forming fluids as well as the precipitation and enrichment of in Chaihulanzi gold deposit. H2O and CO2 are key constituents that controlled the formation and evolution of oreforming fluids.