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The Chagai belt to the north of the Afghan block and the east of the Iranian block in the western part of Pakistan is known for occurrence of Oligocene to Miocene calc‐alkaline magmatic belt. The present study discusses the characteristics of episodic magmatic activities that contributed to mineralization for the Reko Diq porphyry complex in the western part of the Chagai belt. U–Pb dating of zircons from volcanic rocks of the Reko Diq porphyry complex yielded ages of 25.8 ± 1.8 and 12.29 ± 0.44 Ma for two phases of magmatic crystallization. Geochemical analyses of whole‐rock rhyolite and dacite indicate that the rock units are peraluminous calc‐alkaline, derived from Andean‐type subduction. The magma was formed due to partial melting of the thickened mafic lower crust in a continental arc setting in relation to the subduction of the Neotethys along the Makran subduction zone. The abundance of zircons, Hf, REE, U/Pb and Th indicates high degrees of magmatic evolution. Moreover, the Sr and Nd isotopic data indicate the fractional contribution of depleted N‐MORB mantle to the Reko Diq magmas through bulk mixing with magmas derived from the lower continental crust. Short‐lived magmatic systems repeated magma injection, and various episodes of hydrothermal fluid flow have led to the formation of porphyry mineralization. Emplacement of the Reko Diq porphyry complex and related Cu–Au mineralization is associated with a series of tectonic–magmatic events at different episodes of the Oligocene–Miocene times. [ABSTRACT FROM AUTHOR]

The Shuangyuangou copper deposit is located in the southern segment of the Qinling orogenic belt in central China. The ore‐related intrusions include quartz diorite porphyry, granite porphyry and lamprophyre. In this study, we present whole‐rock geochemistry, zircon U–Pb geochronology, trace elements and Lu–Hf isotope data on the Shuangyuangou intrusions which provide critical constraints on the emplacement age, magma origin, petrogenesis and implications for porphyry Cu mineralization in this newly discovered deposit. Zircon U–Pb dating constrains the emplacement age of quartz diorite porphyry, lamprophyre and granite porphyry at 150–147 Ma. The quartz diorite porphyry and granite porphyry display high‐K calc–alkaline I‐type granite affiliation. The rocks show enrichment of LREE and LILE (Rb, Ba), depletion in HREE and HFSE (Nb, Ta, Ti) and absence of Eu anomaly. Zircon εHf(t) values of quartz diorite porphyry, lamprophyre and granite porphyry range from −7.5 to −1.7 with TDM2 ages of 1.3–1.6 Ga. Our data suggest that the parental magma was derived from partial melting of juvenile lower crust and metasomatic lithospheric mantle, with more involvement of mantle material for the lamprophyre. The zircon Eu/Eu* values of 0.55–0.78 suggest high magmatic water content which suppresses the fractionation of plagioclase. In addition, the ΔFMQ values calculated from zircon trace elements range from −0.90 to 2.96 which is a favourable factor for porphyry Cu mineralization at Shuangyuangou. The Late Jurassic Shuangyuangou intrusion and associated Cu mineralization were formed within an intracontinental setting after the collisional assembly of the Qinling orogenic belt. [ABSTRACT FROM AUTHOR]

The Hongyuan porphyry Mo–Cu deposit (PMCD) is a rare example of a "reduced" deposit, in contrast to classical oxidized porphyry Cu or Mo–Cu deposits. It is characterized by an ilmenite–series I–type felsic granitoid intrusion, reduced ore‐forming fluids with methane‐rich fluid inclusions, and widely distributed primary pyrrhotite. Mo–Cu mineralization in the Hongyuan PMCD occurs as disseminated in porphyry, granular in miarolitic cavity, and vein‐type in the quartz vein. These three types of mineralization are generally produced in the late magmatic period, magmatic‐hydrothermal transition period, and hydrothermal period, respectively. Molybdenite from miarolitic cavities shows a greater contribution from mantle fluid, as evidenced by mantle He proportions of 37.6%–16.8%. Molybdenite in quartz veins has relatively lower mantle He proportions of 1.63%–10.5%, indicating a predominantly crustal fluid source. The 3He/4He variations of these two groups of molybdenite illustrate an increasing input of crustal fluid during the magmatic to hydrothermal transition. Molybdenite samples from miarolitic cavities and quartz veins yield a Re‐Os model age of 300.5 ± 3.7 Ma, which is consistent with the U–Pb ages of zircons in the wallrock porphyries (300–302 Ma). This further indicates simultaneous diagenesis accompanied by mineralization. The Sr–Nd isotopic compositions (initial 87Sr/86Sr: 0.703404–0.703552; initial 143Nd/144Nd: 0.512585–0.512655; εNd[t]: +6.56 to +7.90) and young T2DM model ages (421–531 Ma) of the Hongyuan porphyries suggest that these rocks were derived from partial melting of the basaltic lower crust. We propose that mantle‐derived fluids rose up and mixed with fluids from the lower crust under an extensional tectonic setting, forming mantle‐like Sr–Nd–He–Ar isotopic compositions. The pre‐mineralization stage of the Hongyuan reduced PMCD is marked by quartz‐molybdenite ± K‐feldspar ± pyrite veins or veinlets and miarolitic cavities in the intensively potassic alteration zone. These veins formed at high temperatures (400–476°C) and high salinities (47.5–56.6 wt.%). The syn‐mineralization stage is the main metallogenic stage represented by numerous quartz‐molybdenite ± pyrrhotite veins associated with moderate to high temperatures (248°C–424°C) and low to high salinities (1.57–50.1 wt.%). The post‐mineralization stage is characterized by low temperatures (104–270°C) and low salinities (0.35–8.81 wt.%). Fluid immiscibility, mixing with meteoric water, ore fluid‐wall rock interactions, and decreasing temperature and salinity have played important roles during molybdenum mineralization. [ABSTRACT FROM AUTHOR]

Volatile element abundance is a crucial factor triggering mineralization and controlling the enrichment of molybdenum in porphyry deposits. The Chalukou deposit is the largest porphyry Mo deposit in NE China, with an average grade of 0.087% Mo. In this contribution, we present petrology, bulk geochemistry, zircon U–Pb geochronology and Lu–Hf isotopes, and apatite geochemistry for the Chalukou deposit. The intrusive rocks include pre‐mineralization monzogranite, syn‐mineralization quartz porphyry, fine‐grained porphyry and granite porphyry, and post‐mineralization monzogranite and feldspar porphyry. These granitoids are metaluminous to peraluminous, and belong to alkali‐calcic to calc‐alkalic series. Zircon εHf(t) values of granitoids range from +0.2 to +5.7 with corresponding Hf crustal model ages of 805–1170 Ma, indicating a Mesoproterozoic juvenile crustal source modified by mantle‐derived magma. They are characterized by logf(O2) of −16.1 to −9.4, with an average of −12.5, ΔFMQ of +0.8 to +7.9, with an average of +4.5, showing a relatively high oxidation state for the syn‐mineralization magma. The apatites in quartz porphyry have the highest F contents, ranging from 3.61 to 4.62 wt%. At Chalukou, F‐rich magma is conducive to the convection of magma and promotes the efficient separation of differentiation magma, making the magmatic‐hydrothermal fluid circulate many times, eventually resulting in the accumulation of ore‐forming materials on the top of the magma chamber and gradually aggravating mineral enrichment processes. [ABSTRACT FROM AUTHOR]

The Beiya giant porphyry Au deposit is the largest Cenozoic Au deposit in the Jinshajiang Cu–Mo–Au metallogenic belt. Many granite porphyries of ~36 Ma were exposed in the Beiya deposit, including the Wandongshan (WDS) and Hongnitang monzogranite porphyries (HNT–MPs) with economically important Au metal resources, the uneconomic WDS biotite MP, and Putaishan granite porphyry (GP), and subeconomic MPs at Nandaping (NDP) and Matouwan (MTW) prospects. To reveal the fundamental factors that lead to the different fertility of these granitic porphyries, this study uses the biotite and zircon geochemical compositions to evaluate their petrogenetic and magmatic conditions (e.g., F content, pressure, fO2). The results show that biotites from economic WDS and HNT–MPs exhibit moderate F contents (0.85%–2.16%), low n(FeT)/n(FeT + Mg) ratios (average of 0.36), and shallow emplacement depths of 0.19–1.76 km. In contrast, the uneconomic granite porphyries are characterized by variable F contents (0.17%–2.75%), high n(FeT)/n(FeT + Mg) ratios (average of 0.43), and deep emplacement depths of 2.76 to 5.02 km. Moreover, the economic WDS and HNT–MPs display higher average zircon fO2 (ΔFMQ [fayalite–magnetite–quartz] of +0.88) than uneconomic granite porphyries (ΔFMQ of −0.19), further confirming a higher fO2 of the economic granitic porphyries. These features indicate that magmatic fO2 is a critical factor controlling Cu–Au mineralization at the Beiya Au deposit. In comparison with the economic WDS and HNT–MPs, the subeconomic MPs in the MTW and NDP prospects exhibit higher average biotite n(FeT)/n(FeT + Mg) ratios of 0.47 and 0.45, and lower average zircon ΔFMQ of −0.05 and −0.23, suggesting lower magmatic fO2 and thus have relatively weak potentials to form Cu–Au mineralization. Notably, the economic WDS and HNT–MPs have higher biotite XMg ratios than those of the subeconomic and uneconomic granitic porphyries, indicating that the economic MPs were formed by the partial melting of mixed lower crustal materials with more mantle‐derived materials. Therefore, the addition of mantle‐derived materials played an important role in determining the fO2 of the granitic porphyry, thus primarily controlling its fertility of Cu–Au mineralization. [ABSTRACT FROM AUTHOR]

The Tudigou porphyry Cu deposit is located in the central part of the southern Qinling belt. Copper mineralization is closely associated with monzogranite porphyry. Zircon LA–ICP–MS U–Pb dating of monzogranite porphyry suggests that the ages of magmatism at Tudigou vary between 150 ± 1 and 148 ± 1 Ma and overlap with the molybdenite Re–Os age of 150–148 Ma, indicating that the Tudigou intrusion and associated mineralization formed during the Late Jurassic. The enrichment in large‐ion lithophile elements, depletion in high‐field‐strength elements, high Ba/Th and La/Yb ratios, and negative correlation between Dy/Yb and La/Sm ratios, together with narrow ranges of εHf(t) values (εHf(t) = −4.0 to +1.4) suggest monzogranite porphyry was derived from a metasomatized lithospheric mantle with minor crustal components contribution, which is also evidenced by the lead isotopic result. The La/Yb ratios of 30 Mesozoic plutons in the southern Qinling belt were used to calculate the Moho depth, which suggests that the magmatism and mineralization in the region occurred during lithosphere thinning in response to the tectonic transition from compression to extension transitional regime. The calculated oxygen fugacity of the Late Mesozoic porphyry deposits in the Qinling–Dabie orogen have identical ΔFMQ values (averaging +1.4 to +2.4). However, the V/Sc ratios (the proxy for water content) are distinct among different deposit sizes, indicating that the dissolved water in the magma plays a critical role in porphyry‐type mineralization. [ABSTRACT FROM AUTHOR]

This paper discusses the porphyry copper mineralization in A‐type granitoids from the Precambrian shield of the Karbi Hills (Mikir Hills), NE India. The prospective zone lies in the Kuthori‐Bagori of Kaziranga locality of the north Karbi Hills. The host granitoids are characterized by intermediate to high SiO2 (66.30–72.97 wt.%), Na2O (up to 4.90 wt.%), Ba (up to 1,943 ppm), Zr (up to 410 ppm), Y (up to 70 ppm) and Al2O3 (up to 14.77 wt.%) with low concentrations of CaO (up to 1.53 wt.%), and Cu (up to 32.41 ppm) which suggest a consistent granodiorite‐monzogranite host composition, an intraplate emplacement, A‐type chemistry, shoshonitic to high‐K calc‐alkaline and a predominant metaluminous character. Minerals in the investigated granitoids show hypogene alteration features similar to ideal porphyry style mineralization. Remnants of early chalcopyrite‐bornite‐magnetite (Magnetite‐I) veins have been preserved in the distant propylitic zone. The central core zone of potassic alteration shows the dominance of pyrite‐chalcopyrite‐magnetite (Magnetite‐II) assemblages. Mineral chemistry confirms the presence of two types of magnetites: magmatic (Mag‐I) and hydrothermal (Mag‐II). Mag‐I is octahedral, less commonly cubic, or irregular. It has a porous core with trellis‐type ilmenite exsolution lamellae. Mag‐II is non‐porous, devoid of ilmenite exsolution lamellae, has irregular to distinctly octahedral crystal habit and contains micro‐inclusions of pyrite, chalcopyrite, aluminosilicates, manganite and apatite. The progressive chemical purification of igneous magnetite, exacerbated by hydrothermal re‐equilibration, has resulted in a significant reduction in trace element contents such as Ti, Al, Mg, Zn and Cr, and a significant increase in iron content from 89 to ~94 wt.%. A combination of [Ni/(Cr + Mn) vs. Ti + V], and [(Ca + Al + Mn) vs. Ti + V] variation diagrams and upper threshold concentrations for the Kuthori‐Bagori ore effectively separates Mag‐I and Mag‐II. Our field, petrographic and geochemical data indicate that the Kuthori‐Bagori of Kaziranga granitoid of the Karbi Hills (Mikir Hills) in NE India is an ideal location for porphyry copper mineralization. [ABSTRACT FROM AUTHOR]

New LA‐ICP‐MS zircon U–Pb geochronology, whole‐rock geochemistry and Hf isotopic data have been studied on the Taipingtun granite porphyry to determine its petrogenesis and constrain the tectonic setting of the central Great Xing'an Range, northeastern China, during the Early Cretaceous. The results of zircon U–Pb dating suggest that the Taipingtun granite porphyry was emplaced during the Early Cretaceous (122–123 Ma). Geochemically, the granite porphyries have high contents of SiO2 (75.76–78.66 wt%) and (K2O + Na2O) (7.14–8.29 wt%), and low Al2O3 (11.09–12.81 wt%) and CaO (0.15–0.29 wt%), indicating peraluminous and high‐K calc‐alkaline features. Additionally, these rocks are characterized by strong Th, U, K, and Rb enrichment; Ba, Sr, P and Ti depletion; high Ga/Al ratios (10,000*Ga/Al = 2.60–4.92) and negative Eu anomalies (δEu = 0.02–0.13). According to the zircon saturation thermometer results, zircon saturation temperatures range from 756 to 959°C with an average of 823°C, displaying high magmatic temperature for the parental magma. Based on these geochemical characteristics, it can be reasonably inferred that the initial composition of the Taipingtun granite porphyry melts exhibited an A‐type magmatic affinity. Furthermore, zircon grains within the Taipingtun granite porphyry have εHf(t) values of 7.12 to 10.99 and TDM2 model ages of 476–726 Ma. The Ba/La (average 3.89), Nd/Th (average 2.25), Zr/Hf (average 22.55), Ti/Zr (average 2.96) and Rb/Sr (average 4.21) values display the characteristics of crust‐derived magmas. Moreover, these rocks have obviously negative Eu anomalies (average 0.13) and relatively high Y (average 37.83 ppm) and Yb (average 4.15 ppm) contents, suggesting the magmas are generated in a low‐pressure environment. Thus, we consider the primary magmas of the Taipingtun granite porphyry may have been predominantly derived from the partial melting of juvenile crustal rocks at low pressure. Combined with the regional geological data, we suggest that the Taipingtun granite porphyry was formed in an extensional tectonic environment, and possibly related to the subducted Palaeo‐Pacific Ocean Plate in the Early Cretaceous. [ABSTRACT FROM AUTHOR]

The Chaqiabeishan area of the Quanji Massif in NW China is characterized by extensive Li‐rich pegmatites and granites of various ages. In this study, the major and trace element compositions, U–Pb zircon ages, and zircon Hf isotopic compositions of the granites were investigated, including the Garideng porphyritic monzogranite, the Gongkaxiuma monzogranite, and the Narong granitic porphyry. Precise U–Pb zircon dating revealed that these three granites were emplaced at approximately 468, 444, and 245 Ma, respectively. The geologic and geochemical data indicate that the Garideng porphyritic monzogranite and the Narong granitic porphyry are two I‐type granites, and the Gongkaxiuma monzogranite is an A2‐type granite. Based on the Hf isotopes and geochemical data, the Garideng porphyritic monzogranite and the Narong granitic porphyry were derived from partial melting of the relatively deep and relatively shallow juvenile mantle‐derived mafic lower crust, respectively, while the Gongkaxiuma monzogranite was derived from partial melting of the granulitic metamorphic basement. Moreover, tectonically, the Garideng porphyritic monzogranite represents the northward subduction of the South Qilian oceanic plate from 500 to 440 Ma. The Gongkaxiuma monzogranite represents the closure of the South Qilian Ocean by ~440 Ma, and the Narong granitic porphyry represents the Late Permian to Middle Triassic southward subduction of the Zongwulong oceanic plate under the Quanji Massif. [ABSTRACT FROM AUTHOR]

The Kalatongke deposit is the largest Ni–Cu sulphide deposit in the Central Asian Orogenic Belt (CAOB) in northern Xinjiang. The tectonic setting of the Kalatongke deposit and the collision period of the Altai and East Junggar terranes remain controversial. This study involves petrological, geochemical, and geochronological evaluations of granitic porphyries in the Kalatongke. The granitic porphyries are divided into three types according to the characteristics of petrology and geochemistry, dated at ~339, ~325, and ~310 Ma. Type‐1 granitic porphyry exhibits evident syn‐collisional characteristics, with plagioclase phenocrysts extending in one direction. This type is metaluminous (A/CNK <1.1), characterized by low SiO2 and K2O contents, and depleted in Nb, Ta, P, and Ti. Type‐2 granitic porphyry is strongly peraluminous (A/CNK >1.1) and characterized by high SiO2 and Al2O3 but low Sr contents. Type‐3 granitic porphyry is also metaluminous (A/CNK <1.1) and has high SiO2 and K2O contents. The estimated crustal thickness of the Kalatongke area increased from 40 to 55 km from 339 to 310 Ma, thereby indicating that its existence within the collisional orogeny period. According to the estimated emplacement depth of the granitic and mafic intrusions, the crust had been thickening since then. During the late collision period, lithospheric detachment caused by terrane collision resulted in asthenospheric mantle upwelling and formed regional mafic intrusions along the Irtysh fault. [ABSTRACT FROM AUTHOR]

The Yuku is a large porphyry Mo deposit (1.5 Mt at 0.12% Mo) in the Luanchuan ore district of the East Qinling orogen, central China. The economic Mo ore bodies occur as veins, veinlets, and disseminated ore and are developed mainly within the late Mesozoic Yuku porphyritic granite. Molybdenum mineralization is generally associated with potassic and phyllic alteration. Hydrothermal processes in the Yuku deposit are divided into four stages: (I) a quartz–K‐feldspar–biotite ± pyrite stage, (II) a quartz–molybdenite ± pyrite ± K‐feldspar ± sericite stage, (III) a quartz–polymetallic sulphide stage, and (IV) a calcite ± quartz ± fluorite ± pyrite stage. The fluid evolution during these hydrothermal stages was constrained through systematic investigation of fluid inclusions (FIs) and H−O isotopes. Four types of primary or pseudosecondary FIs were recognized in hydrothermal quartz and calcite: two‐phase liquid‐rich inclusions (L‐type), two‐phase vapour‐rich inclusions (V‐type), halite‐bearing (hypersaline) inclusions (H‐type), and three‐phase CO2‐bearing inclusions (C‐type). FIs within Stages I–IV have homogenization temperatures of 375 to >550, 297–400, 198–298, and 149–188°C, with salinities of 0.53–13.18, 0.35–40.23, 5.11–11.81, and 5.71–9.73 wt% NaCl equiv., respectively. In Stage I, coexisting vapour‐rich (V‐type) and liquid‐rich (L‐type) FIs have similar homogenization temperatures (488 to >550°C) and distinct salinities, indicating fluid boiling during the formation of quartz–K‐feldspar–biotite veins at a pressure of 550–700 bar and a lithostatic depth of 2.3–2.8 km. In Stage II, FIs in quartz were also trapped under boiling conditions, as evidenced by coexisting hypersaline H‐type (34.13–40.23 wt% NaCl equiv.) and low‐salinity V‐type (0.35–2.24 wt% NaCl equiv.) inclusions, which formed at temperatures of 309–361°C and hydrostatic depths of 1.0–2.0 km, equivalent to pressures of 100–200 bar. During Stage III, the ore‐forming fluids were cooler (198–298°C) and more dilute (5.11–11.81 wt% NaCl equiv.) due to the involvement of meteoric water, with minimum trapping pressures estimated at <100–150 bar, corresponding to a hydrostatic depth of <1.0 km. In Stage IV, temperatures decreased further to 149–188°C, with lower salinities (5.71–9.73 wt% NaCl equiv.), indicating a post‐ore fluid stage. These data suggest that the mineralizing fluids forming the Yuku Mo deposit changed from early moderate‐ to low‐salinity CO2‐rich fluids in the H2O–NaCl–CO2 system that formed at high temperature and pressure, to late H2O–NaCl low‐salinity fluids that formed at low temperature and pressure. H−O isotopic compositions indicate that the mineralizing fluids had a dominantly magmatic signature but were diluted by meteoric waters. Combining our integrated analysis of the fluid evolution and deposit geology, we propose that fluid boiling and fluid–rock interaction, including intensive potassic alteration, changed the salinity and triggered CO2 escape, leading to a decrease in fO2 and an increase in the acidity of the ore‐forming fluids, which ultimately controlled the deposition of molybdenite in the Yuku Mo deposit. [ABSTRACT FROM AUTHOR]

The Permian–Triassic plutons along the Chifeng‐Bayan Obo Fault, southeastern Inner Mongolia, help to provide important constraints on the craton–orogenic boundary of the North China Craton (NCC) and the eastern Central Asian Orogenic Belt (CAOB) and the regionally coeval Mo–Cu mineralization environment. New LA‐ICP‐MS zircon U–Pb data indicate that two granites from the Baituyingzi Mo–Cu area in Chifeng city were emplaced at ca. 274 Ma and ca. 242 Ma. They have high SiO2 (73.44–77.82 wt%) and Na2O + K2O (8.49–10.28 wt%) contents and are high‐K calc‐alkaline, with very high differentiation indexes (DI = 97.1–98.3) and low Zr saturation temperatures of whole rocks (703–738°C). They are also characterized by (La/Yb)N ratios of 4.09–9.30 and enrichments in Rb and Th relative to Nb and Ta, with pronounced negative Eu (Eu/Eu* = 0.14–0.50), Ba, Sr, P, and Ti anomalies. Comparatively, the Permian granite has slightly higher zircon εHf(t) values (+1.7 to +4.6) than those of the Triassic granite (εHf(t) = −3.4 to +0.1) and is less alkaline‐rich. These results, combined with petrographic data, indicate that they are highly fractionated I‐type granites. The granites were likely derived from Mesoproterozoic juvenile crust that had experienced subduction‐related fluid metasomatism, and the resulting magmas then underwent extensive fractional crystallization. In combination with regional geology, we propose that: (a) the granites have tectonic affinity with the CAOB and serve as spatial markers for monitoring the juxtaposition of the NCC and the CAOB, and (b) the studied granites and coeval porphyry deposits likely formed in a syn‐ to post‐collisional setting. [ABSTRACT FROM AUTHOR]

The timing of closing of the A'nyemaqen Ocean—the north branch of the Palaeo‐Tethys Ocean—and the subsequent continental collision remain controversial. In this study, detailed geochronological and geochemical analyses of the Baishiya granodiorite porphyries in the Dulan area [eastern segment of the East Kunlun Orogen Belt (EKOB)] were conducted. The LA–ICP–MS zircon U–Pb dating analysis revealed that the Baishiya granodiorite porphyries were emplaced during the Late Triassic (~223 Ma) and possess adakitic features, including relatively high SiO2 (67.2–69.0 wt%), Al2O3 (15.2–15.9 wt%), and Sr (416–540 ppm) contents, low Y (10.5–12.3 ppm) and Yb (1.03–1.38 ppm) contents, and high Sr/Y and La/Yb ratios. They belong to the high‐K calc‐alkaline series and show significant light rare‐earth element enrichment, minor Eu anomalies, HFSE depletion, and LILE enrichment. The porphyries record a narrow range of (87Sr/86Sr)i ratios (0.709067–0.709920) and ɛNd(t) values (−6.84 to −5.27) with two‐stage model ages (TDM2) ranging from 1,426 to 1,554 Ma. These geochemical features imply that the Baishiya granodiorite porphyries originated from the partial melting of the thickened Mesoproterozoic lower crust by mixing with minor mantle‐derived material. Late Triassic adakitic magmatism in the eastern segment of the EKOB formed in a post‐collisional extension setting due to the closing of the A'nyemaqen Ocean since Early Triassic. [ABSTRACT FROM AUTHOR]

Porphyry Cu–Au ores areamong the important types of porphyry deposits. Some of these are enriched in Pd and Pt, which in some cases have economic potential for PGE (platinum group element) recovery. The behaviour of PGE and S‐saturation in mafic intrusions associated with porphyry deposits are, however, poorly constrained. Here we investigate the PGE concentrations of gabbroic intrusions from Akcha, Beleuti, and Kalmakyr in the Almalyk porphyry Cu–Au ore field in Uzbekistan through Ni–S analyses employing fire assay‐isotope dilution method. The results reveal extremely high Pd/Ir ratio and a negative Ru anomaly for the Beleuti and Akcha gabbro which we attribute to fractional crystallization of olivine and Ru–Os–Ir alloys. The extremely high Cu/Pd ratio (2.56 × 105–2.98 × 106) and depleted PGE contents of the Kalmakyr gabbro possibly represent immiscible separation of sulphide. During the emplacement of the parental magma of Kalmakyr gabbro, crustal contamination might have resulted in S‐saturation and sulphide segregation. Sulphide‐bearing crust was remobilized during the increasing maturity of the island and long‐lived arc magmatism, which released the sulphide into the hydrothermal system of the porphyry deposit. We propose that this process favoured the enrichment of Pt–Pd and sulphide in the Kalmakyr porphyry Cu–Au deposit. [ABSTRACT FROM AUTHOR]

The research site includes part of the East Asian region within areas of South‐East Russia and the boundary part of North‐East China. The region has abundant precious metal deposits: gold and platinum group elements. The spatial distribution of these deposits is controlled by details of crustal and mantle geodynamics including the presence of faults of different types and kinematics, active plume, as well as by the position of the region above a stagnant oceanic slab. Spatial analysis of position, geodynamics, and synchronous formation of the largest East Asian gold districts (e.g., Aldan, Baley, and Jiaodong) and platinum‐bearing massifs provide insights to their connection with mantle plumes and permeable zones at stagnant slabmargins. The occurrence of ore deposits and mineralization of precious metals inside the slab area is related to disjunctive structures of lower crust and upper mantle, such that their resources are considerably lower. This article considers numerical modeling of permeable tectonic structures exposed into mantle upwelling along active continental margins inside the slab area. Small‐scale structures of this type potentially hold two‐phase alkaline massifs, which control the positions of intra‐slab ore deposits, like the Lazurnoe Au–Mo–Cu porphyry deposit, situated in the southern part of the Sikhote–Alin belt. The small sizes of similar massifs impede their discovery, emphasizing the importance of the proposed prospective model for precious metal‐bearing porphyry deposits in Western Pacific mobile belts. [ABSTRACT FROM AUTHOR]

Zhuno is the only large porphyry copper deposit that preserves the complete magmatic system in the western part of Gangdese porphyry copper belt. Intrusions in the Zhunuo deposit include pre‐ore porphyritic monzogranite, syn‐ore monzogranite porphyry, and post‐ore quartz syenite‐normal granite porphyry, high‐Cr granite porphyry, normal diorite porphyry, high‐Mg diorite porphyry (diorite enclave), potassic lamprophyre, and ultrapotassic lamprophyre. Enriched Sr–Nd isotopic composition and high MgO, LILE, HFSE, LREE, and compatible element (Cr, Ni) contents of the ultrapotassic lamprophyre indicate that the magma derived from the enriched Lhasa lithospheric mantle, which had been metasomatized by fluids and sediment‐derived melts associated with Neo‐Tethyan oceanic subduction and subsequent Indian continental lithosphere subduction. The depletion of the Sr–Nd isotopic composition and MgO (or Mg#), Cr, and Ni content of the normal diorite porphyry manifest that the magma source is juvenile Lhasa lower crust instead of Indian mantle. Geochemical characteristics indicate that the magma sources of the quartz syenite‐normal granite porphyry, high‐Mg diorite porphyry‐diorite enclave, and potassic lamprophyre was derived from ancient Lhasa middle‐upper crust, crust‐mantle transition zone, and enriched Lhasa mantle without Indian lithosphere contribution, respectively. Their similar Sr–Nd isotopic compositions demonstrate a uniform Sr–Nd isotopic reservoir from crust to mantle in Zhunuo area. The major and trace element compositions suggest that the high‐Cr granite porphyry was formed by mixing of quartz syenite‐normal granite porphyry and ultrapotassic lamprophyre magmas. High Sr/Y values and low Y contents of the monzogranite and monzogranite porphyry display adakitic properties. The major and trace element contents and Sr–Nd isotopic composition indicate the monzogranite‐monzogranite porphyry are likely from mixing of the normal diorite porphyry magma with the quartz syenite‐normal granite porphyry magma, rather than with the high‐Mg dioritic (high‐Mg diorite porphyry‐diorite enclave) and/or potassic‐ultrapotassic magmas. According to the spatial and temporal consistency of the adakitic and potassic‐ultrapotassic rocks with the N–S‐trending rifts, Indo‐Asian convergence rate reduction, and uplifting model of Tibetan Plateau, we infer that the magma genesis of the Zhuno intrusions is attributed to decompressional partial melting of Lhasa crust‐mantle triggered by the tearing of the subducting Indian Plate. [ABSTRACT FROM AUTHOR]

The Jiudingshan Cu–Mo deposit is spatially and temporally associated with potassic granitic intrusions (monzogranitic porphyry and porphyritic‐like granite) in a post‐collisional intracontinental setting in Western Yangtze Craton, Western Yunnan, China. Zircon U–Pb dating for granitoids yields the crystallization age of 34.2–35.1 Ma, and that of lamprophyre and diabase is ca. 35 Ma as well. Whole‐rock geochemical data suggest that the granitoids belong to high‐K calc‐alkaline or shoshonite series, and are characterized by enrichment of K, Rb, U, and Th, and depletion ofSr, Ba, Nb, Ta, Ti, and P. The lamprophyre is characterized by high‐K (K2O/Na2O = 3–5), belonging to shoshonite series, and the diabase contains lower K (K2O/Na2O < 0.5), belonging to calc‐alkaline series. A few mafic rock samples have significantly higher REE contents than the granite counterparts. Geochemistry results indicate that the mafic intrusions are not the source of granitic intrusions. Combined with published isotope data, we conclude that the granitic intrusions were most likely originated from partial melting of a Neoproterozoic intra‐crustal amphibolitic source, but mixed with a mantle‐derived component; while the mafic intrusions were originated from partial melting of an EM II mantle source. Felsic magmas from dual sources of crust and mantle could provide Mo and Cu for mineralization, respectively. Trace element analysis of zircons shows that the initial magmas had high oxygen fugacity, which is favourable for the migration of Cu and Mo. Moreover, it can be recognized from the whole‐rock major and trace element data that a relatively weak fractionation occurred during magmatic evolution, which made Mo enriched to a certain extent and at the same time, part of Cu remained in the melt, eventually forming the Jiudingshan Cu–Mo system. [ABSTRACT FROM AUTHOR]

The Bondar Hanza porphyry Cu deposit, hosted by a granitoid stock, is located 120 km south of Kerman city in the elongated NW–SE trending Urumieh‐Dokhtar magmatic arc (UDMA), Iran. The granitoid stock is a multiphase intrusive body, 2 km2 in surface area, which comprises microdiorite–microquartz diorite and granite–granodiorite. Petrological and geochemical analyses show that granitoids are peraluminous, magnesian, calcic to alkali‐calcic, and non‐adakitic intrusions characterized by negative Eu* anomalies. Thermobarometric and oxygen fugacity calculations indicate that magma emplacement occurred at 719–784°C, <100 MPa, and at a log fO2 of NNO +1.6 to +3.2. Sulphur isotopic composition of sulphide minerals (δ34S = 5.0–6.8 ‰) are similar to other porphyry Cu deposits worldwide. Molybdenite separates yield Re–Os ages of 28.22–28.03 Ma, indicating that the Cu mineralization and associated magmatism occurred during the Oligocene. The Bondar Hanza is one of the several granitoids from small porphyry Cu deposits in the UDMA that is related to island arc sub‐productive granitoids. It seems that the largest ore‐hosting porphyry systems within the UDMA are generally restricted to Miocene intrusions with adakitic affinity (e.g., Sarcheshmeh granitoids) and that the temporally discrete non‐adakitic magmatic systems are sub‐productive to barren. These data are interpreted to show that magmatism in the Bondar Hanza region was likely associated with partial melting of juvenile lower crust induced by north‐eastward subduction of the Neo‐Tethys oceanic lithosphere. [ABSTRACT FROM AUTHOR]

Porphyry deposits occur not only in subduction zones, but also in collisional belts worldwide. The magmatic oxygen fugacity (ƒo2) is an important element for the formation of porphyry, and influences the processes in source, migration, and precipitation of Cu and other chalcophile elements. Magmatic sulphur exists mainly as sulphate (SO42−) at higher oxygen fugacity, which combines with chalcophile elements (e.g., Cu, Au) as ion complexes then formed the ore‐bearing magma. In contrast, magmatic sulphur exists mainly as sulphide (S2−), sulphide will precipitate easily. A magmatic event usually involves multiple intrusive activities. These porphyries have various ƒo2 evolutions, implying that they are formed in different formation environments or dynamic mechanisms. In a subduction setting, plates begin to dehydrate and then partial melting occurs in the early stage of subduction. Following the extensive dehydration, partial melting occurs as the plate diving deeper. As a result, the later magma is more oxidative than the earlier one. While under the collisional setting, porphyritic magma is likely related to the previous arc magmatism of subduction or juvenile mantle components in the thickened lower crust. The hydrous and metalliferous fertile magma formed. Then, reduction of water supply is the possible factor that leads to the gradually decrease of ƒo2. As a result of this study, metallogenic elements are usually developed in later porphyritic magma at a subduction environment, but in the early porphyritic magma at a collisional environment. This can provide guidance for prospecting of porphyry deposits in multi‐phases of porphyritic magma districts. [ABSTRACT FROM AUTHOR]

The Tibetan Plateau is characterized by the largest crustal thickness on Earth, although the timing of formation of the plateau remains debated. In this study, we present in situ laser ablation‐inductively coupled plasma‐mass spectrometry zircon U–Pb ages and Hf isotopes, and whole‐rock geochemical data on porphyritic granitoids of Sebuta in the central Lhasa block. Our zircon U–Pb data indicate that these rocks emplaced at ca. 89 Ma, in the early Late Cretaceous. Geochemically, the Sebuta biotite granite porphyry can be broadly divided into two subtypes, namely metaluminous porphyry and peraluminous porphyry. The metaluminous porphyry has high SiO2, Al2O3, Sr, low Y and Yb contents, and high Sr/Y and LaN/YbN ratios, showing adakitic features. These rocks have high K2O and Th contents, low Ti/Eu and Nd/Sm ratios, indicative of a continental crust affinity. Positive zircon εHf(t) values, along with high Mg#, Cr and Ni, imply that the Sebuta adakitic porphyry was most likely derived from partial melting of a delaminated thickened juvenile lower crust, and that the initial melts interacted with mantle peridotite during ascent. The field features, petrographic characteristics, formation age, ore‐bearing potential, and Hf isotope of the peraluminous porphyry are similar to those of the Sebuta adakitic porphyry, indicating that the peraluminous porphyry was likely formed by contamination with ancient crustal material and fractional crystallization from the same primary adakitic magmas which generated the Sebuta adakitic porphyry. Residual phases of amphibole + plagioclase + garnet + rutile in the source region, together with previous studies, suggest that the crust beneath the central‐northern Lhasa block experienced thickening during the early Late Cretaceous, and had already been thickened to more than 50 km by the Late Cretaceous (ca. 89 Ma). [ABSTRACT FROM AUTHOR]

Xuejiping porphyry Cu deposit is located in the south of Yidun island arc, northwest Yunnan. Tectonically, it lies in the middle part of the "Sanjiang Rivers" metallogenic belts. There are ore‐barren quartz diorite, quartz diorite porphyrite (QDP), and ore‐bearing quartz monzonite porphyry (QMP) intruded into clastic‐volcanic rocks of the late Triassic Tumugou Formation. This study focused on determining why the ore‐bearing porphyry is the QMP. It analyzed the correlation between chronology, geochemistry, magmatic oxygen fugacity, and mineralization. Results show that the crystallization age of QDP is 228.7 Ma and that of QMP is 215.0 Ma, which is relatively younger. The molybdenite Re‐Os age is 219.9 Ma. The oxygen fugacity of QDP and QMP magma are higher than Fayalite‐Magnetite‐Quartz buffer, but the oxygen fugacity value of QDP magma is relatively dispersed, with high and low values. While the QMP falls in the high oxygen fugacity range. The δ18O value of QDP (from 5.66 to 6.27 with an average of 6.02) is higher than that of QMP (from 5.53 to 6.42 with average 5.76). It indicates that the QMP contains more components from the mantle than QDP. It is suggested in this paper that QMP have more potential of ore‐formation in the later stage. The QDP caused ore‐forming elements pre‐enrichment in the region. Millions of years later, the QMP intruded in QDP, the pre‐enriched elements were activated and superimposed with the ore‐forming elements of QMP, then the ore‐forming elements were carried and integrated into the ore deposit, and enriched once again. [ABSTRACT FROM AUTHOR]

A set of granite porphyry (grnt‐porphyry) and sub‐rhyolite porphyry (rhy‐porphyry) with specific blue quartz phenocrysts was disintegrated in the northern Kongling terrane, China. Geochemical and isotopic analyses were performed on samples from Kongziqiao (KZQ) and Baizhuping (BZP). In terms of major elements, both are rich in silicon and alkalis, but depleted in calcium and magnesium. Their trace element contents are also similar, exhibiting negative anomalies for large‐ion lithophile elements (LILEs) such as K, Rb and Sr but positive anomalies for high‐field‐strength elements (HFSEs) such as Hf, Ce and Lu. Other elements such as Nb, Ti, P, Sm, Ho, Y and Yb show negative anomalies; however, the KZQ grnt‐porphyry is characterized by positive Ba and negative Zr anomalies; whereas the BZP sub rhy‐porphyry has negative Ba, U and Ta anomalies. The overall geochemistry is characteristic of A‐type granite formed in an extensional environment (A2‐type). Yield ages of the KZQ grnt‐porphyry are (2,239 Ma) and that of the BZP (1,895 Ma) sub rhy‐porphyry are Paleoproterozoic. Analysis of Hf isotopes shows that both have negative ε Hf (t) values, but the εHf (t) value of the KZQ grnt‐porphyry is slightly more positive (minimum −12.4; mean − 8.8) and its depleted mantle model age (TDM1 = 2.85–3.06 Ga, mean 2.92 Ga) is slightly older than the BZP sub rhy‐porphyry (minimum ε Hf (t) = −17.1, mean − 14.9; TDM1 = 2.79–2.92 Ga, mean 2.85 Ga). This suggests that they are derived from partial melting of different generations of ancient crustal material, which implies significant stratification in the Archean crust. The ε Nd (t) values of two samples of each rock type also indicate that both were derived from Ca. 2.9 Ga ancient crust (εNd (t) KZQ = −5.58, −4.74; εNd (t)BZP = −8.55, −8.22). The petrogenesis of both rock types is related to deep crustal extensional collapse caused by post‐orogenic extension before 2.2 Ga and after 1.9 Ga. The formation of two porphyries represents the changes in tectonic system of the Yangtze Block, and this tectonic evolution may have contributed to the reconstruction of the Columbia supercontinent. [ABSTRACT FROM AUTHOR]

Baogutu is a large gold deposit (4 Mt @ 5.5 g/t Au) in West Junggar, NW China. We conducted a Re‐Os geochronological study on seven pyrite samples from auriferous quartz‐pyrite veins, which yielded a Re‐Os isochron age of 312 ± 11 Ma (2σ). This age defines the timing of gold mineralization, and overlaps the emplacement age of diorite to granodiorite porphyry stocks (319–310 Ma) in the Baogutu district. The Os initial ratio of 0.46 ± 0.21 (2σ) suggests a mix of components from both mantle and continental crust in the ore‐forming system, which is similar to the proposed magma source of porphyry stocks. The δ34S values of sulphide minerals vary in a narrow range from +0.1 to −3.3‰, indicating that the sulphur is likely of igneous origin. Our data suggest that the Baogutu gold mineralization is probably genetically linked to the regional diorite to granodiorite magmatism. The new data provide important constraints for an evolving genetic model of the Baogutu gold deposit. [ABSTRACT FROM AUTHOR]

The Xietongmen large deposit is the only known subduction‐related porphyry Cu deposit in the Gangdese Belt, Tibet, which is composed of the No. I and No. II deposits. Previous work suggests that the No. I deposit is reduced while the No. II deposit is oxidized. However, it is ambiguous that both oxidized and reduced porphyry Cu deposits occur in close proximity, in the same tectonic setting, and within a short time period. Detailed examination of the ages, whole‐rock geochemistry, zircon and apatite compositions of the Xietongmen No. I and No. II ore‐bearing porphyries are conducted to investigate their magma characteristics and the genetic types of the Xietongmen No. I and No. II deposits. Zircon U–Pb dating results show that the Xietongmen No. I and No. II ore‐bearing porphyries formed at 166.3 ± 2.6 Ma and 175.5 ± 1.0 Ma, respectively. The Xietongmen No. I and No. II ore‐bearing porphyries have similar mineral assemblage (containing amphibole phenocryst), high Sr/Y ratios and negligible negative Eu anomalies, low Ti‐in‐zircon temperatures (633−749 and 633−763°C, respectively), which indicate that their magmas are water‐rich. In addition, the Xietongmen No. I and No. II ore‐bearing porphyries have: (a) high whole‐rock V/Sc ratios (10−15 and 8−16, respectively); (b) high zircon Ce4+/Ce3+ and EuN/EuN* ratios, falling into the field of the ore‐bearing intrusions in northern Chile; (c) low apatite CeN/CeN* ratios (0.97−1.02 and 0.99−1.02, respectively), which suggest that their magmas are oxidized. The estimated magmatic S contents, based on the magmatic apatite SO3 contents, yield 0.0113−0.0507 wt% and 0.0012−0.0118 wt%, respectively for the Xietongmen No. I and No. II ore‐bearing porphyries, which suggest their magma are sulfur‐rich. Hydrous, oxidized and sulfur‐rich magmas are the parent magma of oxidized porphyry Cu deposits, together with the oxidized minerals of hematite and magnetite, therefore, both Xietongmen No. I and No. II deposit are oxidized porphyry Cu deposits, rather than that the Xietongmen No. I deposit is a reduced porphyry Cu deposit. [ABSTRACT FROM AUTHOR]

Demingding is a poorly studied post‐collisional porphyry Cu‐Mo deposit, located in the eastern part of the Gangdese porphyry copper belt. In this study, we present LA‐ICP‐MS zircon U‐Pb dating, whole‐rock geochemistry, and zircon trace elemental data for the mineralization related biotite monzogranite porphyry in Demingding. Zircon U‐Pb dating shows that the weighted mean 206Pb/238U ages of the Miocene biotite monzogranite porphyry is 20.36 ± 0.46 Ma (MSWD = 2.6, n = 21). The Miocene biotite monzogranite porphyry is characterized by high SiO2, K2O, and Al2O3 contents and shows adakite‐like signatures. These rocks have high Sr/Y ratios, fractionated REE patterns with low HREE abundances, enrichment in LILE compared with HFSE, and have (87Sr/86Sr)i values of 0.7059 to 0.7062, εNd(t) values of −2.35 to −1.67 and (206Pb/204Pb)i ratios of 18.50–18.55. These features are similar to other Miocene adakite‐like intrusions in the Gangdese belt. We propose that the biotite monzogranite porphyry shares the same petrogenesis with other Miocene ore‐bearing adakite‐like intrusions in the Eastern Gangdese belt and was derived from remelting of the subduction‐modified, eclogitized Tibetan lower crust and mixing with hydrous mafic magmas from metasomatized Tibetan mantle. The zircons from biotite monzogranite porphyry have only minimal negative Eu anomalies (EuN/EuN* > 0.3), and exhibit large ratios of Ce4+/Ce3+(average value of 113), 10,000*(EuN/EuN*)/Y (3.94–8.14, >1), Ce/Nd (9–58, Average value of 30), (Ce/Nd)/Y (0.008–0.127, >0.003), and low value of Dy/Yb (0.15–0.24, <0.3), indicating that the biotite monzogranite porphyry is relatively hydrous and oxidized. The biotite monzogranite porphyry, therefore, is believed to be a relatively fertile intrusion with certain exploration potential. [ABSTRACT FROM AUTHOR]

The Tulasu pluton is located in the northeast of the Tulasu Basin, North Tianshan, which is composed of three rock types including quartz diorite porphyry, pyroxene diorite porphyry, and granite. Zircon U‐Pb dating indicates that the quartz diorite porphyry and pyroxene diorite porphyry were crystallized in the Late Devonian (with ages at 360.3 ± 7.8 and 375.4 ± 6.2 Ma, respectively), while the granitic rocks was formed in the Late Carboniferous (at 305.9 ± 5.9 Ma), suggesting that the Tulasu pluton was the product of two magmatic episodes. The Late Devonian quartz diorite and pyroxene diorite porphyry are metaluminous and belong to calc‐alkaline to high‐K calc‐alkaline series. Quartz diorite porphyry and pyroxene diorite porphyry are characterized by the prominent enrichment in LILEs, such as Rb, Th, U, and K, and depletion in HFSEs, such as Nb, Ta, P, and Ti, which is similar to typical subduction‐related arc magma. The εHf(t) values of quartz diorite porphyry and pyroxene diorite porphyry are +4.5–+8.8 and +2.0–+6.4, respectively, indicating that they are derived from depleted mantle wedge. Their TDM2 ages are 814–1,087 Ma and 955–1,227 Ma, respectively, which shows that the Mesoproterozoic to the Neoproterozoic crustal materials were involved. Their high Ba/La (10.26–17.92), low Th/Yb (1.96–5.80), and relatively low Ce/Th (3.16–7.34) and Ba/Th (18.29–38.92) ratios indicate that they were probably produced by partial melting of depleted mantle wedge metasomatized by slab‐derived aqueous fluids, with involvement of subducted sediment. Geochemical characteristics indicate that the Late Devonian dioritic magma was generated in an arc‐related tectonic setting. The Late Carboniferous granitic rocks were composed of granodiorite porphyry and granite porphyry. The granodiorite porphyry samples are high‐K calc‐alkaline and peraluminous, while the granite porphyry samples are in the boundary zones of shoshonite and high‐K calc‐alkaline, as well as metaluminous and weakly peraluminous. Granodiorite porphyry shows features of I‐type granite, while granite porphyry has the characteristics of A‐type granite. High 176Hf/177Hf ratios (0.282600–0.282833) and εHf(t) values (+0.4–+8.7) indicate that granitic rocks have affinities with both depleted mantle and crust. Geochemical characteristics suggest that the Late Carboniferous granitic magma was formed in post‐collisional setting. [ABSTRACT FROM AUTHOR]

The Baishan Mo deposit in the eastern Tianshan Mountains is representative of the local metallogenic Triassic Mo belt. In this study, the geological characteristics, petrography, and geochemistry of the granite porphyry and the Mo deposit were examined using zircon U–Pb dating, molybdenite Re–Os isotope dating, whole‐rock geochemistry, and fluid inclusions. Results show that the crystallisation age of the Baishan granite porphyry is 229.8 ± 1.4 Ma and the Re–Os age of molybdenite in the ore body quartz vein is 225.0 ± 1.2 Ma. Therefore, the ore formed basically at the same time as diagenesis in the Late Triassic. The Baishan granite porphyry has high levels of Si, Al, and alkalis (K2O + Na2O = 5.72–8.88%) and low levels of Mg. The differentiation index is high (81.68–91.20), while the aluminium saturation index is low, indicating that the pluton belongs to metaluminous–weak peraluminous highly fractionated I‐type granite. The rock is also enriched in light rare earth elements (LREE) and large‐ion lithophile elements but depleted in heavy rare earth elements (HREE) and high‐field‐strength elements, with a distinct differentiation between LREEs and HREEs. δEu is weakly negative. The high Sr/Y and La/Yb ratios indicate geochemical characteristics similar to adakite rocks. The formation of the deposit is closely related to Mo‐rich, low‐salinity (1.23‐ to 9.73‐wt.% NaCl eqv.), and medium‐ to low‐temperature (91–280°C) magmatic fluid in the plate extension setting. The magma was derived from partial melting of thickened lower crust and possibly mixed with intrusive mantle‐derived magma. The ore‐forming fluids were uplifted, transported, mixed with meteoric water, and precipitated to form the Mo ore. [ABSTRACT FROM AUTHOR]

Miocene postcollisional potassic and adakitic rocks are widely distributed in the southern Lhasa terrane and western central Lhasa terrane. However, coeval potassic and adakitic rocks in eastern central Lhasa terrane were rarely recognized, and their origins and formation mechanism remain controversial. In this paper, we provide new geochronological and geochemical data for the Miocene postcollisional potassic and adakitic intrusions exposed in the Qingdu area, eastern central Lhasa terrane, southern Tibet. The Qingdu Miocene intrusions consist of quartz monzonite porphyry and biotite granite with coeval zircon U–Pb ages of 14.1 Ma and 14.0 Ma, respectively. They have high SiO2 (67.98–75.32 wt.%), Al2O3 (14.13–14.78 wt.%), and K2O (4.06–6.18 wt.%) and low MgO (0.25–1.46 wt.%) contents. They are both enriched in light rare earth elements (LREEs) and depleted in heavy rare earth elements (HREEs), with high (La/Yb)N (25.37–42.32) ratios. The biotite granite samples have low Y (7.10–9.96 ppm) and Yb (0.61–0.85 ppm) contents, and high Sr (229–384 ppm) contents and high Sr/Y (30–41) ratios, which show adakitic geochemical characteristics, whereas the quartz monzonite porphyry samples show potassic geochemical characteristics. They display initial (87Sr/86Sr)i ratios of 0.7083–0.7103, εHf(t) values of −6.7 to −0.1, εNd(t) values of −8.96 to −7.44, (208Pb/204Pb)i ratios of 39.028–39.110, (207Pb/204Pb)i ratios of 15.662–15.684, and (206Pb/204Pb)i ratios of 18.541–18.577. These signatures indicate that both the potassic and adakitic intrusions are more likely to originate from partial melting of a thickened lower crust, which were mainly the products of the binary mixing between the juvenile and ancient crust components. Based on the spatial distributions and isotopic features of the postcollisional potassic and adakitic rocks in the Lhasa terrane, we suggest that the differences of the lower crustal composition played a crucial role in causing the geochemical variations of the Miocene postcollisional adakitic and potassic rocks in Lhasa terrane. [ABSTRACT FROM AUTHOR]

The Huangshaping world‐class W–Mo–Cu–Pb–Zn deposit formed during Jurassic intra‐continental extension in the central Nanling region (South Hunan), South China. In order to assess the role of fluids in ore genesis and the origin of polymetallic mineralization, three types of mineralized porphyries (quartz porphyry, granophyre, and granite porphyry) were studied. The multi‐method approach included whole‐rock Sr–Nd isotopic geochemistry and determination of the trace element content and gaseous and aqueous composition of ore minerals from the three stages of intrusion and ore emplacement. Geochemical results show that the Sr–Nd isotopes in these altered porphyries were strongly affected by fluid metasomatism. The 87Sr/86Sr and 147Sm/144Nd ratios for the quartz porphyry and granophyre range from 0.72894 to 0.83093 and 0.1524 to 0.2080, respectively, whereas higher and considerably more variable ratios were determined for the granite porphyry (0.90396 to 1.51943 and 0.2391 to 0.2914). These observations imply that granite porphyry‐associated W–Mo mineralization underwent more intensive fluid–rock interaction. The relatively low REE concentrations and high abundances of CH4 and H2 in the Cu ores associated with the quartz porphyry unambiguously suggest a deep‐sourced magmatic fluid for the Cu mineralization. The high REE concentrations, pronounced negative Eu anomalies, M‐type tetrad effects, and high CO2, H2O, and Ca2+ contents of the W–Mo ores associated with the granite porphyry imply that the W–Mo polymetallic mineralization was formed in a relatively oxidizing, high‐temperature environment with strong metasomatism. In contrast, the slightly negative Eu anomalies, W‐type tetrad effects, low CH4, and high F− and Cl− concentrations of the Pb–Zn ores indicate involvement of a sediment‐derived basinal brine and reducing mineralization conditions. Collectively, a three‐stage genetic model is proposed for the Huangshaping polymetallic deposit. Corresponding to initiation, development, and cessation of Jurassic intra‐continental extension, magmatic water, metasomatized fluids, and basinal brines played key sequential roles in Cu, W–Mo, and Pb–Zn mineralization. [ABSTRACT FROM AUTHOR]

The Tuwu deposit is one of the largest porphyry copper deposits in the Eastern Tianshan, Northwest China. Ore bodies of the deposit are associated with the tonalite porphyry, which intruded the Early Carboniferous Qi´eshan Group. The hydrothermal ore‐forming processes include the porphyry mineralization episode with potassic, chlorite‐sericite/albite, phyllic, and propylitic alteration and the overprinting mineralization episode. These hydrothermal alteration episodes were studied on the basis of mass transfer and element mobility. The mass balance data and isocon diagrams reveal that Cu is highly associated with the chlorite‐sericite (albite) stage and followed by phyllic and potassic stages. On the basis of electron probe analysis, the SO3 contents of the igneous apatite from the tonalite porphyries range from 0.016 to 0.288 wt.%, which are higher than those from the diorite porphyries (SO3 = 0.088–0.179 wt.%). Similarly, the apatite saturation temperature (861–926°C) and magmatic S content (mean = 52.16 ppm) from the tonalite porphyries are also higher that from the diorite porphyries (T = 813–877°C; S = 28.25 ppm). These results suggest that the S content of the apatite is related to the temperature and S content of the melt. In the hydrothermal alteration zones, the F favours partitioning into apatite under lower temperature, the F contents of hydrothermal apatite increase from the potassic zones to the propylitic zones accompanying with the decrease of temperature. Cl element is much more sensitive to the pH, pressure, and fluid composition than F element. The Cl contents of the apatite increase from the potassic zones (0.18–0.46 wt.%) to the chorite‐sericite (albite) zones (0.28–0.58 wt.%), resulting from the decrease of fluid pH and pressure. The lower Cl contents of apatite (0.07–0.48 wt.%) in the phyllic zones were due to the lower Cl content of hydrothermal fluids. The highest Cl contents (0.09–0.69 wt.%) of apatite in the propylitic zones were caused by the decrease of pressure. The δ18Owater values of quartz in chlorite‐sericite (albite) zones and phyllic zones range from −0.8‰ to −0.4‰ and from −5.3‰ to 4.8‰, and the δD values vary from −57‰ to −47‰ and from −52‰ to −44‰, respectively. Gaseous compositions of the fluid inclusions in quartz are dominated by H2O with minor CO2, and the liquid compositions mainly consist of Na+ and Cl−. These data imply that the ore‐forming fluids belong to the H2O‐NaCl system and evolved from magmatic water to meteoric water in origin. [ABSTRACT FROM AUTHOR]

Relatively little attention has been given to variations in ore‐forming metal sources of Pb–Zn polymetallic deposits hosted in or near the Linzizong volcanic rocks from the eastern to western Gangdese belt. Based on the S and Pb isotopic data of typical Pb–Zn polymetallic deposits from the eastern to western Gangdese, the ore‐forming sources are discerned. The δ34SV‐CDT values of the typical Pb–Zn polymetallic deposits in the Gangdese metallogenic belt have a relatively large range of −11.6‰ to 6.0‰, different from those of the porphyry Cu ± Mo ± Au deposits (mainly vary from −2.0‰ to 1.0‰) in the Gangdese metallogenic belt, indicating that the sulphur in the ore‐forming fluid of Pb–Zn polymetallic deposits was dominantly of magmatic origin, but also influenced by strata nearby. The Nuocang and Beina deposits in the western Gangdese have a predominantly upper crustal source of Pb (average values: 207Pb/204Pb = 15.705, 208Pb/204Pb = 39.102), while the Narusongduo and Dexin deposits in the central Gangdese and the Leqingla and Xingaguo deposits in the eastern Gangdese are characterized by a mixed source in which Pb was derived from both the subducted slab and the ancient Lhasa basement. From the eastern to western Gangdese, Pb isotopic data show a gradually increasing scale of crustal materials from the Lhasa terrane basement. Combined with the geochemical data of the ore‐related intrusions and Linzizong volcanic rocks from the six deposits, or nearby, we proposed that the heterogeneity of Lhasa terrane crust resulted in more ancient Lhasa basement components contributing to ore‐forming sources from the eastern to western Gangdese. Moreover, relatively higher contents of Au, Ag elements could be identified in the Linzizong volcanic rocks of the western Gangdese than those of in the central and eastern Gangdese. Therefore, in addition to finding the cryptoexplosive breccia, epithermal, skarn, hydrothermal vein‐type Pb–Zn polymetallic deposits, there is exploration potential for epithermal Au–Ag deposits associated with the Linzizong volcanic rocks, western Gangdese. [ABSTRACT FROM AUTHOR]

The newly discovered Zhunsujihua porphyry Mo deposit is located in the south‐western part of the Great Hingan Range, north‐east China. Molybdenum mineralization generally presents as veins or disseminations hosted in granitic intrusions, and multiple‐stage hydrothermal activity has resulted in potassic, phyllic, and sericitic alteration. The mineralization process can be divided into four stages, that is, quartz–K‐feldspar ± pyrite veinlets in stage I, quartz–molybdenite veinlets in stage II, quartz–polymetallic sulfide veinlets in stage III, and barren quartz–calcite veins in stage IV. Four types of fluid inclusions can be distinguished by petrography in hydrothermal quartz, including liquid‐rich two‐phase, vapour‐rich two‐phase, pure gaseous, and pure liquid inclusions, but quartz in stage I contains all types of fluid inclusions. The homogenization temperatures in quartz of stages I, II, III, and IV vary from 300°C to 520°C, 230°C to 410°C, 170°C to 260°C, and 136°C to 227°C, with salinities of 4.18–13.30 wt.% NaCl equiv., 2.07–11.10 wt.% NaCl equiv., 1.74–8.95 wt.% NaCl equiv., and 0.70–5.71 wt.% NaCl equiv., respectively. The ore‐forming fluids in this deposit are characterized by high temperature and intermediate to low salinity belonging to an H2O–NaCl system. δ18Oquartz values of quartz from stages I to IV range from +5.5‰ to +10.1‰, with the calculated δ18Ofluid values ranging from –6.7‰ to +6.3‰, and the δD values of fluid inclusion waters in quartz ranging from –118‰ to –102‰. The δ34S values of pyrite and molybdenite from different ore stages range from 3.8‰ to 6.8‰ with an average of 5.1‰. Pyrite and molybdenite samples in the deposit have 206Pb/204Pb ratios of 18.394 to 18.766, 207Pb/204Pb ratios of 15.580 to 15.694, and 208Pb/204Pb ratios of 38.309 to 38.942. All these observations reveal that the hydrothermal fluids of the Zhunsujihua porphyry Mo deposit have a dominantly magmatic signature with an input of meteoric water during the carbonate stage, and the ore‐forming components (metal and sulfur) were sourced from a greater magmatic source and some upper crustal materials. [ABSTRACT FROM AUTHOR]

The Tiantangshan tin‐polymetallic deposit, located in the Nanling Range of South China, is a medium‐sized polymetallic deposit found in the region in recent years. The deposit is hosted within volcanic rocks, and the orebodies occur in the cupola and outer contact zone of the concealed quartz porphyry, as well as the altered fracture zone of the volcanic rocks close to the intrusive contact. In light of field evidence and petrographic observations, the mineralization can be divided into four stages: greisenization stage (stage I), quartz–cassiterite–wolframite stage (stage II), quartz–fluorite–cassiterite–sulfides stage (stage III), and post‐ore stage (stage IV). Three types of fluid inclusions are present in the hydrothermal topaz, quartz, and fluorite, including H2O‐rich (W‐type, WL‐ and WV‐ subtypes), CO2‐bearing (C‐type), and solid‐bearing (S‐type). Four stages of fluid evolution are observed by detailed fluid inclusion studies: (a) Stage I fluids are trapped under two‐phase immiscible condition, as evidenced by the coexistence of primary aqueous (W‐type) and aqueous‐carbonic (C‐type) fluid inclusions preserved in topaz and quartz; the fluid inclusions display homogenization temperatures of 378–448°C and salinities of 6.0–17.5 wt.% NaCl equiv. (b) Similarly, fluid inclusions in stage II quartz also record immiscible condition, as identified by the coexistence of W‐type and C‐type fluid inclusions with lower homogenization temperatures (308–400°C) and salinities (1.8–14.5 wt.% NaCl equiv.). (c) Stage III fluids are characterized by the coexistence of widespread WL‐subtype, minor S‐type, and rare WV‐subtype fluid inclusions, with similar homogenization temperatures (230–369°C) but contrasting salinities (0.5–39.5 wt.% NaCl equiv.), which indicates an episode of fluid boiling occurred in this stage. (d) Stage IV marks the end of the hydrothermal system characterized by the lower temperatures (175–298°C) and salinities (0.2–3.9 wt.% NaCl equiv.) W‐type fluid inclusions trapped. Microthermometry and H–O isotopes indicate that the early ore‐forming fluids (in stage I) exsolved from the granitic magma and underwent progressive mixing with meteoric water during subsequent ore‐forming process (in stages III and IV). The water–CO2 fluid immiscibility is the main mechanism of cassiterite and wolframite precipitation, while fluid boiling and mixing are probably thought to be the dominant mechanisms for the deposition of sulfide at Tiantangshan. 40Ar/39Ar dating of hydrothermal biotite intergrown with cassiterite shows that tin‐polymetallic mineralization occurred at ~133 Ma which is coeval with the hidden intrusions. Taken together, these lines of evidence confirm that the Tiantangshan deposit is a magmatic hydrothermal greisen–quartz–vein type tin‐polymetallic deposit that formed in the lithospheric extension and thinning setting associated with the postsubduction Paleo‐Pacific Plate tectonic regime that influenced South China. [ABSTRACT FROM AUTHOR]

The newly discovered Yongxin Au deposit in the Lesser Xing'an Range of north‐eastern Heilongjiang Province, NE China, has a resource of ~20 t with a grade of 4.1 g/t Au. The deposit is hosted by Carboniferous syenogranite and mylonite, and Cretaceous diorite porphyry and granite porphyry. The syenogranite has a LA‐ICP‐MS 206Pb/238U zircon age of 316 ± 2 Ma, and both the granite porphyry and diorite porphyry yield an age of 119 ± 1 Ma. The Rb–Sr isochron age of Au‐bearing pyrite from hydrothermal breccia‐type ore is 107 ± 4 Ma, and this is interpreted as the mineralization age of the Yongxin deposit. In combination with published geochronological data, we argue that epithermal Au mineralization in NE China formed during the period ca. 124 to 107 Ma and was produced during rollback of Palaeo‐Pacific oceanic slab. The Cretaceous epithermal Au deposits are distributed in the Erguna Massif, Lesser Xing'an Range, Zhangguangcai Range, and Jiamusi and Nadanhada terranes. In combination with the coeval porphyry Mo deposits present in these areas, we propose that the Erguna Massif, Lesser Xing'an Range, north‐eastern Great Xing'an Range, and eastern Jiamusi and Nadanhada terranes, where only epithermal gold deposits were discovered up to date, might be prospective for concealed porphyry Cu or Mo deposits. [ABSTRACT FROM AUTHOR]

The Lhasa terrane is one of the major segments of the Tibetan Plateau, with widespread Mesozoic to Cenozoic magmatic and metallogenic records. Here, we investigate timing and characteristics of magmatism associated with the Lunggar Fe skarn deposit in Central Lhasa. We also present Sr–Nd–Pb and Hf (zircon) isotopic data on three associated intrusions to gain insights on the tectonic and metallogenic evolution of the region. Our data reveal at least two magmatic pulses in Lunggar represented by Early Cretaceous I‐type granodiorite (112.9 ± 1.5 Ma) and granite porphyry (112.6 ± 1.3 Ma) with magma generation related to slab break‐off associated with the Bangong–Nujiang Ocean during closure of the Meso‐Tethyan ocean at ~113 Ma. Iron skarn mineralization at Lunggar was contemporaneous with local Early Cretaceous intrusive activity. Following this, Late Cretaceous adakitic diorite (90.5 ± 1.5 Ma) formed from delaminated thickened crust at ~91 Ma related to the northern subduction of the Yarlung‐Zangbo oceanic plate. We also provide a comprehensive review of the Cretaceous tectonic evolution of Central Lhasa, which trace the tectonic evolution as follows: (a) 145–120 Ma: southward subduction of the Bangong–Nujiang oceanic plate under the Lhasa terrane; (b) 120–115 Ma: Lhasa‐Qiangtang continental collision; (c) 115–110 Ma: slab break‐off of the Bangong–Nujiang Ocean; (d) 110–95 Ma: crustal thickening of the Central Lhasa lower crust; (e) 95–80 Ma: delamination of lithospheric mantle; and (f) 80–65 Ma: northward subduction of the Yarlung‐Zangbo oceanic plate and subsequent slab rollback. The related metallogenic events in Central Lhasa include (a) ~115–110 Ma skarn Fe mineralization associated with slab break‐off; (b) ~90–80 Ma porphyry Cu–Au mineralization formed in delaminated thickened crust of Central Lhasa; and (c) ~65 Ma skarn Pb–Zn mineralization produced from slab rollback of the Yarlung‐Zangbo Ocean. [ABSTRACT FROM AUTHOR]

The Caosiyao giant porphyry Mo deposit (1.76 Mt), which is the third largest such deposit in China, is located on the northern margin of the North China Craton and associated with the Caosiyao intrusive complex that was emplaced in Archaean metamorphic rocks. The intrusive complex consists of monzogranite and coarse‐, medium‐, and fine‐grained granite porphyries that yield U―Pb ages of 148.5 ± 1.2, 146.4 ± 1.0, 144.6 ± 1.0, and 142.8 ± 3.2 Ma, respectively. Four molybdenite Re―Os model ages range from 143.1 ± 2.4 to 145.3 ± 2.1 Ma, which are consistent with the U―Pb ages for the igneous complex. The geochronological data indicate that the multistage magmatic‐hydrothermal processes were important in the formation of the Caosiyao giant deposit. The rocks of the Caosiyao granitic complex have high contents of silica (SiO2 = 71.7–75.6 wt.%) and total alkalis (mostly K2O + Na2O > 8 wt.%), low contents of CaO and MgO, and exhibit peraluminous high‐K calc‐alkaline to shoshonitic affinities. They are enriched in large‐ion lithophile elements (e.g., K, Rb, U, and Th) and light REEs and depleted in Eu, Ba, Sr, Nb, P, and Ti. The geochemical characteristics indicate advanced fractional crystallization and that the rocks are strongly fractionated I‐type granites. The negative Hf isotopic compositions of the granitic rocks, combined with old two‐stage Hf model ages, indicate the magmas were derived from partial melting of the ancient lower crust of the North China Craton. All the intrusive rocks in the complex have relatively high Ce4+/Ce3+ ratios and oxygen fugacity, which would have facilitated Mo extraction into the melts owing to the much higher solubility of S as sulphate (SO42−) than sulphide (S2−). The magma crystallization temperatures decreased from 882°C to 770°C as the magma evolved. The multistage magmatic‐hydrothermal processes, and the prolonged fractional crystallization, combined with high magma oxygen fugacity are the key factors to form the Caosiyao giant Mo deposit. The tectonic setting of deposit formation was one of extension related to rollback of the subducting Palaeo‐Pacific Plate during the Late Jurassic to Early Cretaceous. [ABSTRACT FROM AUTHOR]

SHRIMP and LA–ICP–MS zircon U–Pb dating, Nd and Hf isotope analyses, 40Ar/39Ar geochronology, and whole‐rock geochemistry indicate three episodes of magmatism in the Dabaoshan ore district, South China: (1) Caledonian dacites (ca. 438 Ma); (2) Indosinian dolerites (ca. 210 Ma); and (3) Yanshanian granodiorites/porphyries (ca. 165 Ma) and basalts (ca. 147 Ma). Episode 1 dacites and episode 3 granodiorites/porphyries are enriched in Rb, Th, U, and LREEs and depleted in Nb, Ta, Sr, P, and Ti. The dacites may have been derived from partial melting of Mesoproterozoic–Paleoproterozoic crustal material, whereas the granodiorites/porphyries were derived mainly from partial melting of a late Mesoproterozoic crustal source with minor inputs of mantle material, according to whole‐rock εNd(t) and zircon εHf(t) values. The geochemical characteristics of episode 2 dolerites and episode 3 basalts, as well as their positive εNd(t) values (3.3–5.9 and 3.5–4.0, respectively), suggest a depleted mantle source. Taking into account the tectonic evolution of the South China Block, we suggest episode 1 dacites and episode 2 dolerites formed in an extensional setting that resulted from lithospheric delamination during the Caledonian intraplate orogeny and orogenic collapse during the Indosinian intraplate orogeny. Episode 3 granodiorites/porphyries and basalts formed in a back‐arc extensional setting in response to the westwards subduction of the Palaeo‐Pacific Plate beneath the South China Block. The timing of the three episodes of magmatism coincides roughly with the published ages of mineralization in the Dabaoshan ore district, suggesting a genetic relationship. [ABSTRACT FROM AUTHOR]

The subduction–collision processes associated with the Indo‐Eurasian plates resulted in the formation of a major belt of porphyry copper deposits in the eastern Tibetan Plateau. Identifying the emplacement depths of the ore‐hosting porphyry intrusions and quantifying their denudation degree, which in turn is a function of the uplift and structural history, are fundamental to formulate guidelines for ore prospecting. In this study, we investigate three important porphyry deposits located adjacent to the Diancangshan–Ailaoshan Suture. From SW to NE, these are the Bijiashan, Xiaolongtan, and Fenshuiling deposits. Our study focuses on the relationship among uplift, denudation, and mineral preservation through the application of mineral thermobarometry, integrated with published zircon U–Pb dates. Application of amphibole–plagioclase thermobarometry yields emplacement temperature–pressure (T–P) conditions of 833.99°C and 284.18 MPa for Bijiashan, 804.72°C and 163.88 MPa for Xiaolongtan, and 748.67°C and 116.70 MPa for Fenshuiling. Our data show a progressive decrease in the emplacement depth from southwest to northeast, with average depths of 9.80 km in the Bijiashan deposit, 5.65 km in the Xiaolongtan deposit, and 4.02 km in the Fenshuiling deposit, providing important clues on the exhumation history since the Eocene in the eastern Tibetan Plateau. Higher degree of denudation and faster uplift are noticed close to the Diancangshan–Ailaoshan Suture, with all the deposits belonging to the shallow denudation category and large prospecting potential. We integrate these results with geochronological data, alteration characteristics, and exhumation parameters to trace the tectonic history and to provide guidelines for exploration. [ABSTRACT FROM AUTHOR]

The Tulasu Basin is an important epithermal gold ore cluster situated in the Boluokenu Polymetallic Belt, Western Tianshan, China. The Axi Au, Tabei Pb–Zn, and Tawuerbieke Au deposits in this basin represent different types of epithermal mineralization. These are products of the same tectonic‐magmatic‐hydrothermal event, related to the southward subduction of the North Tianshan Ocean beneath the Yili‐Central Tianshan Plate during the Late Devonian to Early Carboniferous. The spatial relationships, preservation levels, and evolution of the three deposits are still debated. Hence, systematic geological field investigations, ore microscopy, and isotopic analyses were carried out on these three deposits. The S–Pb–C–H–O isotopic compositions indicate that the ore‐forming components were derived from the volcanic‐subvolcanic rocks, as well as from circulating meteoric waters. The occurrence of adularia, silicified platy carbonates, and quartz characterized by crustiform/colloform/colloidal textures at Axi indicate that boiling was the main precipitation mechanism for the Au mineralization. The Pb–Zn ores from Tabei are characterized by abundant banded coarse‐grained quartz crystals with dog tooth and comb textures, suggesting that the sulphides precipitated slowly due to conductive cooling. The Tawuerbieke Au deposit is characterized by pervasive silicification and phyllic alteration accompanying veinlet and disseminated ore, which formed via metasomatic water–rock interaction. According to the ore textures, intrusion sizes, and mineral assemblages, it can be inferred that all three deposits experienced different extents of erosion (Axi < Tabei < Tawuerbieke) and that there is exploration potential for concealed porphyry Cu–Au mineralization. Exploration should focus on deep targets beneath the Tawuerbieke Au deposit. [ABSTRACT FROM AUTHOR]

The Changfagou copper deposit, a newly discovered porphyry deposit in the southern Jilin Province, NE China, is tectonically located on the northeastern margin of the North China Block. We recognized four types of sulfide‐quartz veins at Changfagou, including quartz–K‐feldspar–magnetite veins (Stage I), quartz–molybdenite–pyrite–chalcopyrite veins (Stage II), quartz–chalcopyrite–pyrite–galena–sphalerite veins (Stage III), and quartz–carbonate veins (Stage IV). Three types of fluid inclusions, including liquid‐rich two‐phase (L‐type), vapour‐rich two‐phase (V‐type), and daughter mineral‐bearing multi–phase (S‐type) inclusions, have been distinguished. The fluid inclusions in the quartz phenocrysts of the ore‐hosting granite porphyry contain liquid‐rich two‐phase, gas‐rich two‐phase, and daughter mineral‐bearing multi‐phase fluid inclusions. Stages I, II, and III quartz contain all types of fluid inclusions, whereas only L‐type inclusions can be observed in Stage IV quartz. The fluid inclusions in the quartz phenocrysts of the granite porphyry yield homogenization temperatures ranging from 282 to 586 °C and salinities ranging from 3.55% to 58.41% NaCl equiv. The fluid inclusions in the quartz of Stages I, II, III, and IV mainly homogenized at temperatures of 290 to 492 °C, 270 to 424 °C, 248 to 398 °C, and 119 to 219 °C, respectively, with salinities of 9.98–50.85 wt.% NaCl equiv, 6.30–46.37 wt.% NaCl equiv, 6.45–35.99 wt.% NaCl equiv, and 6.59–18.04 wt.% NaCl equiv, respectively. The ore–forming fluids of the Changfagou Cu deposit are therefore characterized by their high temperature and high salinity, and they belong to the H2O–NaCl–CO2 system. The δ18Ofluid values of quartz phenocrysts and vein quartz range from −9.97‰ to +6.91‰, and their δDfluid values range from −142‰ to −93‰, indicating that the early‐stage ore‐forming fluids mainly consisted of magmatic water that experienced the input of magmatic and meteoric water during the last stage. The δ34S values of chalcopyrite and molybdenite range from +2.2‰ to +4.3‰, with an average value of +3.17. The 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios of granite porphyry, arsenopyrite, and pyrite range from 16.672–17.567, 15.516–15.658, and 37.210–38.733, respectively. Both the S and Pb isotopic systems indicate that the ore‐forming materials were derived from mixed mantle and crustal sources. We thus proposed that multiple stages of the boiling of ore‐forming fluid represented the dominant mechanism of the formation of the Changfagou Cu deposit. [ABSTRACT FROM AUTHOR]

Central Jilin is tectonically subordinate to the Lesser Xing'an Range–Zhangguangcai Range polymetallic metallogenic belt, an important region for Cu–Mo prospecting in NE China. Dozens of large‐scale molybdenum deposits, including Fu'anbu, Chang'anbu, Jide, and Dashihe, have been recently discovered in Central Jilin, whereas porphyry Cu or Cu–Mo deposits have not been found to date. One such example of an intracontinental porphyry Cu–Mo deposit is the Chang'anbu Cu–Mo deposit in Shulan, Jilin Province, hosted in early Yanshanian rocks. Here in this contribution, we described detailed geology based on our field observation and conducted a comparative study on the metallogenic epoch and the ore‐forming sources of the Chang'anbu Cu–Mo deposit by using zircon U–Pb dating and H–O–S–Pb stable isotopes. We propose that the Chang'anbu deposit is rare in the Lesser Xing'an Range–Zhangguangcail Range metallogenic belt and differs from other porphyry deposits that consist solely of Mo, indicating a unique mechanism of metallogenesis. Zircon U–Pb ages indicate emplacement of a granite pluton which is the main metallogenetic rock body during the Early Jurassic (182.10 ± 1.20 Ma). The pluton is spatially and temporally associated with Cu–Mo mineralization and led to large‐scale porphyry Cu–Mo mineralization during the early Yanshanian. Sulphur, Pb, H, and O isotope data suggest that magma generated by subduction of the Paleo‐Pacific oceanic crust was the main ore‐forming source of this deposit (206Pb/204Pb = 18.046–18.734; Pb207/Pb204 = 15.502–15.655; δ34S = 0.3–2‰; δDV–SMOW = −102.2–93.4‰; δ18OV–SMOW = 9.1–11.6‰). The Chang'anbu porphyry Cu–Mo deposit is representative of large‐scale polymetallic metallogenic events in Central Jilin that resulted from magmatism related to crust and mantle melting during the early Yanshanian. [ABSTRACT FROM AUTHOR]

Diabase dikes are extensively distributed in the Xiongcun porphyry copper–gold district in the southern margin of the Lhasa terrane. Here, we report zircon U–Pb ages determined by laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) along with Hf isotopic, whole‐rock elemental, and Sr–Nd–Pb isotopic data for these diabase dikes. Zircons from one of the Xiongcun diabase dikes yielded an emplacement age of 165.3 ± 1.0 Ma. The Xiongcun diabase dikes display subalkaline features and tholeiite compositions. They are enriched in large‐ion lithophile elements (e.g., Rb, Ba, and K) and light rare earth elements and are depleted in high‐field‐strength elements (e.g., Nb, Ta, and Ti). The Xiongcun diabase dikes exhibit relatively low ratios of (87Sr/86Sr)i (0.70386–0.70501), (206Pb/204Pb)i (18.15–18.40), (207Pb/204P)i (15.52–15.57), and (208Pb/204Pb)i (38.06–39.46) and relatively high values of εNd(t) (5.85–6.92) and εHf(t) (+12.58 to +14.03). Combined with previous research results, these findings suggest that the Xiongcun diabase dikes and Early Mesozoic magmatic rocks in the southern margin of the Lhasa terrane formed in an active continental margin magmatic arc setting related to the northward subduction of the Neo‐Tethys oceanic slab; however, the possibility that the Xiongcun diabase dikes were formed in an intra‐oceanic arc setting cannot be excluded. Their parental magmas were formed by the partial melting of the depleted mantle source that was modified by fluids released from the Neo‐Tethys oceanic slab. The magmas experienced fractional crystallization of olivine and clinopyroxene and underwent limited crustal contamination during magma emplacement. The ~165 Ma Xiongcun diabase dikes, which probably originated under an extensional stress condition in a magmatic arc setting, correspond to the timing of Middle Jurassic subduction‐related porphyry copper mineralization (161–172 Ma) in the southern margin of the Lhasa terrane, likely suggesting that this episode of mineralization occurred during a period of changing stress from compression to extension. [ABSTRACT FROM AUTHOR]

Late Carboniferous to Early Permian granitic rocks are widely distributed in the Western Junggar (Xinjiang, NW China), but their petrogenesis and tectonic contexts remain controversial. In this paper, we present new zircon U–Pb age, major element, trace element data for the Huangliangzi pluton from the southern West Junggar. The pluton mainly consists of granodiorite porphyry, biotite monzonitic granite porphyry, and quartz monzonite diorite porphyry. Laser‐ablation inductively‐coupled mass‐spectrometry (LA‐ICP‐MS) zircon U–Pb obtained the age of 321.7 ± 1.3 Ma, indicating the granodiorite porphyry was emplaced in the early Late Carboniferous, coeval with abundant magmatic rocks in the region. Geochemically, these rocks are moderately peraluminous high‐K calc‐alkalic and characterized by relatively high SiO2 (64.31–66.69 wt.%), Al2O3 (15.82–16.73 wt.%), and Sr (379–489 ppm) contents and low MgO (1.08–2.46 wt.%; Mg# = 39–55), Y (7.61–9.64 ppm), and Yb (0.95–1.23 ppm) contents, along with positive Eu anomalies (Eu/Eu* = 1.01–1.34) and high Sr/Y (47.7–57.1) ratios. These are compositional features of adakites that are commonly assumed to have been produced through partial melting of subducted oceanic crust. In addition, the adakitic rocks are relatively enriched in light rare‐earth elements (LREEs), large ion lithophile elements (LILEs: e.g., Rb, Ba, Sr, and K), and depleted in high‐field‐strength elements (HFSEs: e.g., Nb, Ta, and Ti) and are also characterized by high εNd(t) value and low initial (87Sr/86Sr)i ratio. The most plausible mechanism for the Huangliangzi adakitic porphyries is the partial melting of subducted oceanic crust interacting with a mantle wedge. Combined with the geological setting and previous studies, therefore, we suggest that the southern West Junggar was in a subduction‐dominated island‐arc setting in the early Late Carboniferous, and multistage subduction–accretionary orogeny may be the main mechanism for the difference between the north and the south subduction duration in the Western Junggar. [ABSTRACT FROM AUTHOR]

The Darbut tectono‐magmatic zone in the West Junggar terrane (NW China) is an important component of the famous Circum‐Balkhash‐West Junggar metallogenic province. In this region, the discovery of some small but high‐quality Cu–Au deposits/prospects indicate substantial exploration potential for large porphyry Cu–Au deposits, for example, those in the neighbouring Kazakhstan. In this contribution, we concluded that the Dulunhe granite and small ore‐bearing granitoids in Baogutu are adakitic petrogenesis, and the Buerkesitai and Tasikuola granites (formed by magma mixing) are well comparable with the Xiaerpu granite. In summary, granitoids with similar petrogenesis and mineralization are distributed on both sides of the Darbut fault zone and show good correlations with the sinistral movement of the latter. We propose that the porphyry Cu–Mo–Au mineralization potential of the small calc‐alkaline I‐type granitic stocks in southern West Junggar region is significantly higher than that of alkaline A‐type large granitic batholiths. Besides, the magma mixing‐derived and adakitic granites have great prospecting potentialities. We argue that the Cu–Mo–Au mineralization in the Darbut tectono‐magmatic zone was originally E‐W trending, and then displaced by the Darbut sinistral strike‐slip faulting, instead of being controlled by NE‐NNE trending faults. The main regional mineralization pattern comprises a northern magmatic‐hydrothermal Au belt (~318 Ma), a middle porphyry Mo belt (~296 Ma), and a southern adakite and magma mixing granite‐related Cu–Au belt (~313 Ma). We infer that the Bieluagaxi Au belt may continue eastward to east of Sartohay. [ABSTRACT FROM AUTHOR]

The Mengxi porphyry copper deposit, situated in the eastern Junggar, Central Asian Orogenic Belt, is not a typical porphyry copper deposit, and the origin of the deposit has been a topical debate for a decade. The ore bodies of the Mengxi porphyry copper deposit mainly developed in the volcanic‐sedimentary terrane (Huangcaopo Group) near a granite porphyry, with strong wall‐rock alteration as well as vertical zonation and fracture‐related vein fillings. The result of zircon U–Pb dating indicates that the granite porphyry was emplaced at 432.6 ± 6.7 Ma. The granite porphyry has relatively low initial 87Sr/86Sr ratios (0.70465–0.70537), high whole‐rock ƐNd(t) values (−2.2 to 6.6), and similar geochemical affinities of adakites and Andean island arc volcanic rocks, indicating that the Mengxi granite porphyry was derived from the partial melting of the upper mantle modified by slab‐derived fluids, with negligible assimilation of crust. Pyrites from the porphyry and volcanic‐sedimentary terrane have a similar δ34S and Pb isotopic compositions, indicating that different pyrites may have similar source. Based on the detailed field investigation, observed mineral assemblages, and crosscutting relationships, massive fine anhedral chalcopyrite and bornite disseminated in the Huangcaopo Formation, chalcopyrite as inclusion in pyrite veins in the contact zone, and the amount of Cu‐bearing minerals increased from terrane to veins have been recognized. All these observations reveal that the ore‐forming materials of the Mengxi copper deposit were mainly derived from the metasomatic alteration of the Huangcaopo Group triggered by the extensive Early Devonian tectonic‐magmatic events. [ABSTRACT FROM AUTHOR]

The newly discovered Xingwen porphyry Mo deposit is located in the most southern segment of the Xiaoxing'an Range–Zhangguangcai Range metallogenic belt (XZMB), NE China. The Mo deposit occurs with a granitic complex consisting of monzogranite, porphyritic granite and felsite porphyry. The Zircon U–Pb ages of monzogranite, porphyritic granite and felsite porphyry are 170.3 ± 2.1, 168.5 ± 2.5, and 166.7 ± 1.6 Ma, respectively. The inherited zircons from the monzogranite and porphyritic granite yield U–Pb ages of 239.8 ± 5.8 and 249.4 ± 6.2 Ma, respectively. These ages reveal that the Mo mineralization in the most southern segment of the XZMB took place in the Middle Jurassic, and is consistent with the epoch of the largest Daheishan Mo district in the XZMB. In contrast, Triassic ages of the inherited zircons are consistent with the ages of the Triassic magmatic activities along the E–W trending tectono‐magmatic belt in the northern margin of the North China Craton. The εHf(t) of the monzogranite, porphyritic granite and felsite porphyry change from −17.1 to +6.7 , −16.9 to +2.9, −5.94 to −0.90, respectively. The Hf isotopic compositions indicate that old crustal source, juvenile crustal source or depleted mantle contributed to their origin. When compared with the granite in Daheishan Mo district in XZMB, the εHf(t) probably indicates that the granitic complex in the margin of the Central Asia Orogenic Belt may have more old crustal materials than the granitic complex in the inner region of the Central Asia Orogenic Belt. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The age, petrogenesis and geodynamic implication of Xiaomiaogou granite porphyry dykes in the northern margin of the North China Craton were investigated using geochronology, geochemistry and Sr-Nd-Pb-Hf isotopic data. LA-MC-ICP-MS zircon U-Pb dating yielded the concordant 206Pb/238U weighted mean age of 350.4 ± 1.4 Ma for the dykes, suggesting they were the productions of the Early Carboniferous magmatism in the northern margin of the North China Craton. The granite porphyries display the pronounced A-type affinities: apart from higher zircon saturation temperature, they are high-K calc-alkaline and metaluminous, with high concentrations of K2O + Na2O varying from 7.93 to 8.55 wt.%, incompatible elements (e.g. Zr, Y, Nb and Ce), REEs and 10 000 Ga/Al ratios but less obvious LREE and HREE fractionation. With the lower initial 87Sr/86Sr ratios (0.7055 to 0.7070), negative values of εNd( t) (−7.1 to −4.9) and εHf( t) (−11.2 to −8.0) and old Nd (1505 to 1681 Ma) and Hf (1861 to 2061 Ma) model ages, all the rocks exhibit the similar geochemical compositions to the melts obtained in experimental studies by dehydration melting of meta-basalts, implying a lower continental crust origin. However, the high Mg# values (47.53 to 53.60) and subcontinental lithospheric mantle-like εNd( t), εHf( t) and Pb isotopic compositions ((206Pb/204Pb)i = 17.296-17.766, (207Pb/204Pb)i = 15.460-15.490 and (208Pb/204Pb)i = 37.097-37.568) indicate the involvement of melts from subcontinental lithospheric mantle. Combined with the special features of mafic microgranular enclaves occurring within the granite porphyries, mixing of the lower crust and subcontinental lithospheric mantle of the North China Craton is proposed for the genesis of granite porphyry dykes in this study. During the hybrid magma ascending, pronounced fractional crystallization and crustal assimilation may have also occurred. Based on geochemical criteria, the Xiaomiaogou granite porphyries can be classified into A1 group. Characterized by the compositional features of anorogenic granites, an intraplate setting is envisaged for the formation of Xiaomiaogou granite porphyry dykes. Such a tectonic environment may be related to the northward drift of the North China Craton during rifting away from East Gondwana. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abundant Cu and Mo deposits are spatially related to granitic complexes in the Nuomin area, eastern Da Hinggan Mountains, China. The petrogenesis of these deposits is investigated using data from zircon U-Pb dating, whole-rock major and trace element geochemistry, and Sr-Nd-Pb isotopic compositions. The results show that the fine-grained biotite monzogranite and medium-grained biotite syenogranite formed in a Late Jurassic (155.7 ± 3.6 Ma) collision environment, characterized by fluid-melt interaction and plagioclase differentiation. These rocks belong to the high-K calc-alkaline, K-peraluminous series, indicating that the parent magma evolved from the low-temperature partial melting of lower crust, with geochemistry consistent with Neoproterozoic oceanic crust. The monzonitic diorite porphyrite, monzonite porphyry (with a crystallization age of 130.64 ± 0.74 Ma) and quartz monzonite porphyry belong to the high-K calc-alkaline, sodic, quasi-aluminous series. The results indicate petrogenesis in a post-collisional or late-orogenic tectonic environment, characterized by interactions with CO2-rich fluid and the fractional crystallization of amphibole, biotite and apatite. The parent magma formed from the partial melting of residual Neoproterozoic oceanic crust. The circulation of mineralized fluids was related to the petrogenesis of the monzonitic diorite porphyrite, monzonite porphyry and quartz monzonite porphyry. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The Hongshan quartz monzonite porphyry is one of the Yanshanian intrusions in the southern part of the Yudun Arc. Detailed zircon U-Pb data of four samples yielded ages of 78.8-80.7 Ma, indicating that the Hongshan intrusion was emplaced during the late stage of Late Cretaceous. The Hongshan intrusion shows shoshonitic and high-K calc-alkaline, with A/CNK = 0.64-1.14. The rocks show an obvious fractionation between light and heavy rare-earth elements (average [La/Yb]N = 38.85), with negative Eu anomalies (Eu/Eu* = 0.60-0.87), enrichment in large-ion lithophile elements (Rb, Th, U and K) and depletion in high field-strength elements (Nb, Ta and P). Rocks have high Sr and low Y content which are characteristics of adakitic rocks, suggesting magma derivation from thickened lower crust. In order to evaluate the nature of the source region, Hf isotope data of zircons were acquired through LA-MC-ICPMS. The negative and variable εHf(t) values demonstrate that the Hongshan intrusion was derived from ancient crust, without mantle-derived components and is significantly different from the Triassic intrusions in the southern part of the Yudun Arc. The three Yanshanian intrusions in Hongshan, Relin and Tongchangou are remarkably similar in terms of geochronology, geochemistry and Hf isotopes. We therefore infer that these intrusions had the same magmatic source and we correlate the tectonics with northward subduction of Tethys underneath the Asian continent. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The Dashui porphyry granitoids in the western Qinling Orogen are spatially associated with the Dashui gold deposit, but their ages and tectonic setting have not been well defined yet in previous studies. This paper reports the results and understandings obtained from our original study in geochronology and isotope and element geochemistry. SHRIMP zircon U-Pb dating yielded ages of 213.7 ± 2.7 Ma for granitic stock and 215.1 ± 2.5 and 210.2 ± 1.6 Ma for granitic dikes. The granitoids are characterized by high LREE but low HREE and HFSE. They have (87Sr/86Sr) i ratios of 0.706 to 0.709 and εNd(t) values of −5.3 to −7.6. The majority of zircons in the Dashui granitoids have εHf(t) values ranging from −6.2 to 6.7 and TDM2(Hf) ages from 743 to 1464 Ma. The isotope signatures, together with La/Y and Mg# values, show that the magmas are mainly sourced from partial melting of a subducted slab, and possibly assimilated immature sediments during upward migration. Thus, the Dashui granitoids most likely formed in a volcanic arc where supra-subduction zone melts assimilated lower crustal material no later than 215 Ma. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]