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• Identification of the Suolong Cu-rich porphyry is suggestive of a new mineralization event. • The porphyry was generated from crust-mantle interactions during the roll-back of subducted NTO. • The features of magma promoted the enrichment of Cu, but thinned crust limited the scale of deposit. The Tibetan Plateau hosts the majority of porphyry Cu deposits in China. There are two large metallogenic belts, the Gangdese and Bangong-Nujiang belts, in the Lhasa Terrane, Central Tibet. The Lhasa Terrane experienced multistage magmatic activity from the Mesozoic to Cenozoic, and the subaerial volcanic areas of the western part of the terrane are regarded as favorable targets of porphyry Cu deposits. In this paper, we describe the geology of our newly identified Early Cretaceous Suolong Cu-rich porphyry in the western Lhasa Terrane and present new U–Pb ages, trace element and Hf isotopic compositions of zircon and whole-rock elemental and Sr–Nd isotopic compositions. The Suolong porphyry contains zircon grains with ages ranging from 136 to 135 Ma, ε Hf (t) values ranging from −1.5 ∼ +2.7 and log f O 2 values ranging from −16.27 ∼ −9.92. Geochemically, the porphyry rocks are peraluminous in nature, with whole-rock ε Nd (t) values of −5.7 ∼ −5.4. We infer that the Suolong porphyry originated from a mixture of ∼53 % enriched lithospheric mantle and ∼47 % ancient lower crustal melt, triggered by the roll-back of the northward-subducting Neo-Tethyan Ocean. The conditions of high oxygen fugacity and water content and tectonic transition promoted the formation of the Suolong Cu-rich porphyry, but the condition of a thinned crust may have constrained the mineralization scale of the Cu deposits. This new identification of Early Cretaceous mineralization event provides important clues for identifying new potential exploration targets for porphyry Cu deposits in the western segment of the Lhasa Terrane. [ABSTRACT FROM AUTHOR]

• The first in-situ LA–ICP–MS dating of titanite in the A vein of porphyry deposits has been analyzed in polished thin section. • The titanite dating data (44.4 ± 1.5 Ma) in the A1 vein of the Lancang Laochang polymetallic deposit further delineates the evolutionary timeline from magma to ore-forming fluid in 45–43 Ma. • From magma to the initial ore-forming fluid in the Laochang deposit, a slightly pressure increase (from 93 MPa to 98 MPa) and a minor decrease of temperature (from 697 °C to 680 °C) and log f O 2 (from −16.78 to −17.29) have been revealed. The Laochang polymetallic deposit is the only large deposit in the Changning–Menglian Junction Zone. The deposit features by deep porphyry-skarn Mo–(Cu) and shallow vein Pb–Zn–(Ag) mineralization. Researches on the deposit have yielded extensive data, however, details about the initial evolution from magma to ore-forming fluid remain unclear. This study centers on the in-situ analysis of biotite from the porphyry, as well as phlogopite and titanite from the A vein, leading to the following insights: (1) The biotite geothermobarometer suggests the porphyry intruded in a moderate depth (2.57–4.27 km), with average parameters as P = 93 MPa, T = 697 °C, and log f O 2 = -16.78. (2) The A vein in the deposit can be further subdivided into A1 K-feldspar vein and A2 quartz vein. The phlogopite in the A1 vein formed at P = 98 MPa, T = 681 °C, and log f O 2 = -17.29. The pressure of the A1 vein is slightly higher than the static pressure of wall rock, attributed to pressure increment from the initial exsolved fluid. Conversely, the temperature and oxygen fugacity experience a slight decrease, due to buffering of the adjacent tuff. (3) The in-situ LA–ICP–MS U–Pb dating of the titanite in the A1 vein yields 44.4 ± 1.5 Ma (MSWD = 1.8, n = 48), comparable to the emplacement age of the porphyry (44.6–44.4 Ma). It is slightly older than the main mineralization age (43.78 Ma), further delineated the initial evolution sequence from magma to ore-forming fluid. Our research suggests that the in-situ analysis of titanite is crucial for preciously tracking the magma–fluid system, as titanite records both time and temperature information. [ABSTRACT FROM AUTHOR]

Explanation: From Lakange Mo (Cu) deposit to Jiama Cu polymetallic deposit to Bangpu Mo mineralization to Qulong Cu-Mo deposit to Bangpu Cu mineralization, the Cl contents in apatite gradually increase, but the F contents in apatite gradually decrease, and the S content is similar but variation. It indicates that the Mo-dominated porphyry deposit formed from F-S-rich magma, whereas the Cu-dominated porphyry deposit formed from Cl-S-rich magma. [Display omitted] • There are two different magmatic-hydrothermal systems that formed the Bangpu Mo-Cu deposit. • Cu and Mo mineralization contain zircon and apatite with different geochemical features. • Cu mineralization was related to Cl-rich porphyry system, whereas Mo-mineralization was related to F-rich porphyry system. The Bangpu deposit, located in the eastern part of the Gangdese Porphyry Copper Belt, Tibet, is a porphyry Mo-Cu deposit in a continental collisional orogenic belt. Cu and Mo mineralization occurred separately in the Bangpu deposit. Mo (Cu) mineralization occurred mainly in the monzogranite porphyry (MP), while Cu (Mo) mineralization occurred mainly in the diorite porphyry (DP). The cause of such spatial differences in Cu and Mo mineralization in the Bangpu deposit remains unclear. In this study, the mineral chemistry of apatite and zircon was investigated to reveal the differences in the nature of ore-forming magma between Cu (Mo) and Mo (Cu) mineralization in the Bangpu deposit. The chondrite-normalized REE patterns of the apatite grains from the MP were enriched in LREEs with negative Eu anomalies, whereas those from the DP and biotite monzonitic granite (BM) had strong negative Eu anomalies with no obvious differentiation between LREEs and HREEs. The DP, MP, and BM have a low T TiZ range from 657 °C to 917 °C and a high AST range from 687 °C to 1079 °C. The zircon grains from the DP and MP had different Th/U ratios and T TiZ values, indicating that these porphyry samples probably experienced different magma crystallization or crystal fractionation histories. The zircon Ce4+/Ce3+ and Eu/Eu* ratios indicate that the ore-bearing DP and MP have higher oxygen fugacity than the BM. The F, Cl, and S contents in the apatite showed that the DP magmas were Cl- and S- rich, whereas the MP magmas magmas were F- and S- rich. The Bangpu porphyry Mo-Cu deposit results from two superimposed magmatic-hydrothermal systems. Mo was mainly partitioned into the F-rich magmatic-hydrothermal system released from the MP, and Cu was mainly partitioned into the Cl-rich magmatic-hydrothermal system released from the DP. Our results show that zircon and apatite geochemistry can be used to explain the spatial distribution of Cu and Mo mineralization in porphyry Cu-Mo systems. [ABSTRACT FROM AUTHOR]

To reveal the hydrothermal evolution from porphyry Mo to vein-style Zn-Pb mineralization, the Chalukou deposit in NE China with these two typical mineralization overprinted is selected for detailed research. From early to late hydrothermal veins, the quartz cathodoluminescence intensities change from bright to dark and the textures also evolve. The Ti concentrations of quartz in these veins change from high to moderate and then to low values. The fluid inclusion petrography, microthermometry and stable isotope analyses indicate intermediate-density magma-derived fluids (δ18Owater = +4.7 to + 6.2‰, δD = −132 to −136‰) exsolved at high temperatures (560° to 600 °C) with low to moderate salinity (2.4 to 8.0 wt% NaCl equiv) containing minor CO 2 (<5.7 mol %). Early minor molybdenite occurred under lithostatic conditions at high temperatures (540° to 580 °C) during fluids pH change and early magnetite precipitation. Later main molybdenite precipitation at moderate temperatures (350° to 430 °C), result from fluid cooling and involving of meteoric water under the transition from lithostatic to hydrostatic conditions. The precipitation of pyrite in transitional veins at moderate temperatures (330° to 420 °C), and the late sphalerite-galena from a lower-temperature fluid (180° to 300 °C) is consistent with the cooling of magmatic fluid, and gradually dilution with meteoric water under hydrostatic conditions. It is deduced the transition from porphyry Mo to vein-style Zn-Pb mineralization is likely driven by progressive decrease in temperature of the magmatic fluids and the increasing influx of meteoric water. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cu–Au deposits in the XCAOB are mainly distributed in Altay, Junggar, and Tianshan. • Volcanogenic, porphyry, IOCG, intrusion-related, epithermal, skarn, and orogenic types. • Five mineralization phases, of which Devonian and Carboniferous are the main phases. • Island arc, continental arc, collision, and postcollisional extensional settings. Northern Xinjiang (Altay, Junggar, Tianshan, and Beishan) is an important part of the Central Asian Orogenic Belt (CAOB) and is characterized by multiple episodes and multitype mineralization in the Late Paleozoic. Cu and Au deposits predominantly occur in northern Xinjiang; however, the geological characteristics and spatiotemporal distribution of Cu–Au deposits remain unclear. The Cu–Au deposits are largely distributed in Altay, Junggar, and Tianshan, with minor deposits in Beishan. We recognize seven types of Cu–Au deposits in the Xinjiang Central Asian Orogenic Belt (XCAOB): volcanogenic, porphyry, iron oxide–copper–gold (IOCG), intrusion-related, epithermal, skarn, and orogenic. Of these types, volcanogenic and porphyry deposits are the most common. Ore formation in Cu–Au deposits can be divided into five mineralization episodes: Late Ordovician–Middle Silurian, Devonian, Early Carboniferous, Late Carboniferous–Early Permian, and Middle–Late Permian. Among these episodes, the Devonian and Carboniferous are the main mineralization episodes, during which porphyry, intrusion-related, IOCG, and volcanogenic deposits formed. The Cu–Au deposits in the XCAOB developed in diverse tectonic regimes, including island arc, continental arc, collision, and postcollisional extensional tectonic settings. [ABSTRACT FROM AUTHOR]

• Reporting Mesoproterozoic felsic magmatism in Northern Karbi Hills. • Mesoproterozoic granitoids refer to a U-Pb zircon age of 1644 ± 33–1550 ± 25 Ma. • Magma input from upper mantle in post collision rift basin. Extensive Mesoproterozoic magmatism occurred in the Karbi Hills Massif, NE India, providing a key to understanding the early geodynamic evolution of Karbi Craton during the Columbia (Nuna) supercontinent cycle. We present here LA-ICP-MS zircon U–Pb ages, Lu–Hf isotopic and geochemical data of Panbari-Geleki-Dallamara and Kuthori granitoids in the Kaziranga area in northern Karbi Craton. These granitoids occur as stock like bodies intruded into the Late Archean-Paleoproterozoic Basement Gneissic Complex, supracrustals and previously emplaced mafic magmatics. Due to subsequent tectono-thermal activities, the older magmato-sedimentary sequences suffered variable degrees of metamorphism and deformations. The U/Pb zircon geochronology indicates that these granitoids were emplaced over a span of about 94 m.y., subsequent to the emplacement of mafic dykes, sills and stocks in a post collision rift basin, now represented by the 'Shillong Basin'. The Karbi Hills granitoids are younger (1644 ± 33–1550 ± 25 Ma) than the Meghalaya felsic magmatics (1778 ± 37–1620 ± 9.2). Basin formation and sedimentation began in the Shillong Basin (Shillong Group) as early as 1900 Ma and continued till 1400 Ma, coinciding with the assembly and dismantling of Columbia supercontinent. Early Proterozoic psammopelitic sedimentation prior to and/or after the mafic-felsic intrusions is now represented by the 'Shillong Group'. The mafic magmatics occur in the craton, present a continental flood basalt character. The chemical makes up state that the granitoids bear mostly metaluminous but weakly peraluminous, A-type, within plate characters. The granitoids are highly potassic and silica saturated (up to 74.3 wt% SiO 2), REE deficient, K, Rb and Ba enriched but Nb, Ti and P depleted. The zircon ɛ Hf(t) for granitoids show a variation up to 7 εHf units (+1.5 to +9.9), however, 13% grains possess negative ɛHf(t) values. This is particularly ascribed to minor mixing of magmas sourced from depleted mantle and metasomatised continental crust. There is, however, no record of any vestige of ophiolite preserved in the craton that would support an active subduction mechanism responsible for this part of early Mesoproterozoic magmatic episode. [ABSTRACT FROM AUTHOR]

• Porphyritic intrusions at Yulong were emplaced over a short period of time, with the mineralized Yulong intrusion being the youngest one. • Magmatic oxidation and hydration states increase as magmas evolve. • All the intrusions are relatively oxidized, hydrous and S-rich, and have the potential to form porphyry deposits. • Magmatic recharge events might be the trigger for extensive fluid exsolution and mineralization at Yulong. The Yulong porphyry Cu-Mo ore district in eastern Tibet features a series of Eocene felsic porphyry intrusions, only one of which is intensively mineralized. In this study, zircon U-Pb ages, and major and trace element compositions of whole rock samples and in-situ accessory minerals (zircon, apatite and titanite) from these various intrusions were analyzed to determine the factors controlling Cu mineralization. New zircon U-Pb dating, together with published zircon U-Pb ages, suggest that these porphyry intrusions were emplaced over a relatively short period of time (43.9 ± 0.6 Ma to 40.9 ± 0.3 Ma), with the mineralized Yulong intrusion emplaced at a late stage of the magmatic activity (41.1 ± 0.3 Ma to 40.9 ± 0.3 Ma). These intrusions have indistinguishable whole-rock major and trace element compositions, but the mineralized Yulong intrusion has higher apatite and titanite La/Yb ratios (average apatite La/Yb = 115.1 ± 28.5, n = 52; average titanite La/Yb = 22.4 ± 4.9, n = 38) than the earlier subeconomic intrusions (average apatite La/Yb = 50.4 ± 12.3, n = 72; average titanite La/Yb = 12.4 ± 3.5, n = 58), suggesting more fractionation of amphibole from the magmas that sourced it. Additionally, a negative relationship between La/Yb and Ce N /Ce N * ratios in apatite and titanite are interpreted to reflect increasing oxidation states through magma evolution. Indistinguishable zircon Eu N /Eu N * values and apatite core SO 3 contents from the mineralized (zircon Eu N /Eu N * = 0.69 ± 0.06, n = 25; apatite SO 3 = 0.65 ± 0.24 wt%, n = 21) and subeconomic intrusions (zircon Eu N /Eu N * = 0.62 ± 0.05, n = 64; apatite SO 3 = 0.61 ± 0.27 wt%, n = 15) suggest that the entire magmatic suite was relatively oxidized, hydrous and sulfur-rich, and was therefore fertile for ore-formation. However, apatite crystals from the mineralized Yulong intrusion have significantly lower Cl contents (0.08 ± 0.03 wt%, n = 72) and higher F/Cl ratios (47.80 ± 21.97, n = 72) than those from the subeconomic intrusions (Cl = 0.29 ± 0.29 wt%; F/Cl = 12.87 ± 5.16; n = 78). These data may reflect more extensive fluid exsolution from the parental magma chamber at the time of emplacement of the mineralizing Yulong magmas. Sudden and voluminous release of volatiles coeval with emplacement of the Yulong intrusion was triggered by an as yet unidentified process, but possibly including magmatic recharge. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Zircon U–Pb dating indicates the emplacement of Ruocuo adakitic porphyries during the Early–Middle Jurassic (182–170 Ma). • Ruocuo adakitic porphyries were generated by the partial melting of the Neo-Tethys oceanic slab. • Formation of Early Mesozoic magmatic rocks in the southern Lhasa subterrane in a magmatic arc setting. • The northern Xigaze forearc basin has a potential for subduction-related porphyry Cu–Au mineralization. Abstract Jurassic adakitic rocks in the southern Lhasa subterrane are relatively rare, poorly documented, and their petrogenesis and geodynamic setting are unclear. To explore these issues, we present zircon U–Pb ages along with Hf isotopic, whole-rock geochemical, and Sr–Nd–Pb isotopic data for hornblende quartz diorite porphyry (HQDP) and quartz diorite porphyry (QDP) in the Ruocuo area, southern margin of the Lhasa terrane, Tibet. Zircon U–Pb dating for these rocks indicates that they were emplaced in the Early–Middle Jurassic (182–170 Ma). Geochemically, HQDP and QDP both show characteristics of adakites, with intermediate SiO 2 (60.62–65.63 wt% and 57.46–60.04 wt%, respectively), relatively high Al 2 O 3 (14.23–18.23 wt% and 18.32–20.14 wt%, respectively) and Sr (344–571 ppm and 514–614 ppm, respectively), and low Y (9.12–13.0 ppm and 11.0–14.9 ppm, respectively) and Yb (0.93–1.31 ppm and 1.08–1.52 ppm, respectively). In addition, they show relatively low ratios of (87Sr/86Sr) i (0.7038–0.7045), (206Pb/204Pb) i (18.31–18.42), (207Pb/204Pb) i (15.56–15.66), and (208Pb/204Pb) i (38.36–38.77) and relatively high values of ε Nd (t) (+5.54 to +6.33) and ε Hf (t) (+11.8 to +17.3). The Sr–Nd–Pb–Hf isotopes of HQDP and QDP are similar to those of the Yarlung Tsangpo ophiolites, indicating that they were predominantly generated by the partial melting of the subducted Neo-Tethys oceanic slab. The subducted Neo-Tethys oceanic slab-derived adakitic rocks that are present in the southern Lhasa subterrane provide strong evidence for proving the presence of oceanic subduction during the Early–Middle Jurassic. By combining our results with the previously reported results, we suggest that the Ruocuo adakitic rocks and Early Mesozoic (Late Triassic to Middle Jurassic) magmatic rocks in the southern Lhasa subterrane formed in a magmatic arc setting related to the northward subduction of the Neo-Tethys oceanic slab, that the initial subduction of the Neo-Tethys oceanic slab occurred prior to the Early Jurassic, and that the upwelling asthenosphere, triggered by the roll-back of the subducted Neo-Tethys oceanic slab, provided the heat that was required for slab melting. However, contrasting these results with the geochemical characteristics of the No. 2 deposit in the Xiongcun Cu–Au district leads us to consider that the Early–Middle Jurassic subducted oceanic slab-derived adakitic porphyries contain a greater potential for porphyry Cu–Au mineralization than the Early Mesozoic normal magmatic rocks in the southern Lhasa subterrane. Furthermore, mineralized Jurassic porphyry has been reported in the Ruocuo area, adjacent to the northern Xigaze forearc basin, indicating that the northern Xigaze forearc basin also has the potential for subduction-related porphyry Cu–Au mineralization. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The Naoniushan deposit is an epithermal-porphyry Cu-polymetallic deposit. • This deposit formed in earliest Cretaceous and is younger than granodiorite porphyry. • Ore-related intrusions were derived from melting of a thickened juvenile lower crust. • The setting was linked to the transition from a compressional to extensional regime. Abstract The Naoniushan Cu-dominated polymetallic deposit in the central Great Xing'an Range is associated locally with Pb-Zn-Ag or Mo mineralization. Mineralization mainly occurs in the Lower Cretaceous continental volcanic rocks. Here, we present new LA-ICP-MS zircon U-Pb ages, whole-rock geochemical data, Sr-Nd-Hf isotopic data, and Re-Os ages for the Naoniushan deposit. The emplacement of the porphyry occurred at 137.8 ± 1.4 Ma and the mineralization at 134.3 ± 0.8 Ma. The granodiorite porphyry has high SiO 2 (67.84–73.70 wt%) and K 2 O + Na 2 O (7.67–8.30 wt%) contents and low contents of MgO (0.60–1.04 wt%, Mg# = 0.44–0.51), TFeO (1.29–2.16 wt%), CaO (1.67–3.66 wt%) and K 2 O/Na 2 O (0.75–0.87). The porphyry is rich in large ion lithophile elements (LILEs, e.g., Rb, Sr, Ba, and K) and light rare earth elements (LREEs), without significant Eu anomalies (δEu = 0.84–1.01), and depleted in heavy REE (HREEs) with LREE/HREE = 12.78–16.57 and (La/Yb) N = 15.37–20.68, high field strength elements (HFSEs, e.g., Nb, Ta, and Ti) and siderophile elements (e.g., Cr, Co, and Ni). These features are similar to those of adakitic rocks derived from thickened lower crust. The Naoniushan porphyry exhibits positive ε Nd (t) values ranging from +1.9 to +2.8 and relatively low initial 87Sr/86Sr ratios, ranging from 0.70458 to 0.70497. Most in-situ zircon Hf isotopic analyses show variable positive ε Hf (t) values ranging from +3.1 to +9.4, corresponding to relatively young two-stage Hf model ages ranging from 994 to 591 Ma (excluding one spot). These isotopic features suggest that the primary magma of the Naoniushan granodiorite porphyry was mainly derived from the partial melting of Neoproterozoic juvenile lower crust (comprising a mixture of 80% juvenile basalt and 20% ancient lower crust). These elemental, isotopic, and geochronologic data, combined with the regional geology, deposit geology and fluid characteristics, suggest that the Naoniushan Cu-dominated polymetallic deposit formed in an evolving environment that decreased in compression over time due to slowing of the subduction of the Paleo-Pacific Plate beneath the Eurasian Plate, and the transition from a compressional to an extensional tectonic regime following the closure of the Mongol-Okhotsk Ocean. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Ore-forming tonalite porphyry has high oxygen fugacity and sulfur contents. • Three hydrothermal alteration stages are recognized. Decreasing of t emperature and pressure result in copper precipitation. • Copper transported by brine at high to low temperature, but also by vapor at high temperature. Abstract The Aktogai Group (more than 12.5Mt of Cu and 80t of Au) is located in the western part of the Central Asian Orogenic Belt (CAOB). The mineralization of the Aktogai deposit is associated with the Early Carboniferous tonalite porphyry which intruded into the Koldar complex. The ore-forming tonalite porphyry has higher oxygen fugacity and sulfur contents than those of wall rocks based on results of mineralogical chemistry analyses. Hydrothermal fluid activities result in the potassic, sericite(-chlorite) and propylitic alteration, and are associated with disseminated and/or vein mineralization. The alteration and mineralization include three stages. Potassic stage is characterized by hydrothermal K-feldspar, biotite, magnetite, "A" veins and disseminated mineralization. Sericite(-chlorite) stage that partly overprinted on potassic stage is characterized by sericite, chlorite, "C" veins and disseminated mineralization. Propylitic stage is characterized by chlorite, epidote and "C" veins, and develops in the tonalite porphyry and wall rocks. Five types of fluid inclusions have been recognized in the Aktogai deposit, including liquid-rich (L-type), vapor-rich (V-type), daughter mineral-bearing (S-type), CO 2 -bearing (C-type) and minor SO 2 -bearing fluid inclusions. In the potassic stage, ore-forming fluid belongs to H 2 O-NaCl-CO 2 system with four types fluid inclusions, homogeneous temperatures and salinities of fluid inclusions are 320 °C to 448 °C and 0.35 wt% to 51.08 wt%, respectively. In the sericite(-chlorite) stage, the fluid belongs to H 2 O-NaCl-CO 2 system with L-type, V-type and C-type fluid inclusions, homogeneous temperatures and salinities of fluid inclusions are 243 °C to 315 °C and 1.22 wt% to 13.27 wt%, respectively. In the propylitic stage, the fluid belongs to H 2 O-NaCl system with L-type and V-type fluid inclusions, homogeneous temperatures and salinities of fluid inclusions are 211 °C to 328 °C and 0.35 wt% to 11.46 wt%, respectively. A relatively negative δ34S‰ values (−4.61‰ to −3.18‰) indicate that the sulfur derived from a high oxygen fugacity magma. Decreases of the temperature, pressure and oxygen fugacity of the ore-forming fluid result in metal precipitation in the Aktogai deposit. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Au-related intrusions crystalized at 269–270 Ma in the Bilihe porphyry gold deposit. • Later molybdenite mineralized at 268 Ma. • Hf–O isotopes trace a mixing source between mantle and continental crust for ore-related magma. Abstract The Bilihe gold deposit in Inner Mongolia is situated in the Central Asian Metallogenic Domain. Its major orebody II is a porphyry-type body, spatially and temporally associated with granodiorite porphyry and granite aplite. In this study, the timing of gold mineralization is precisely constrained by using the zircon U–Pb dating for pre-mineralization intrusions and the molybdenite Re–Os dating for later molybdenite veins. Furthermore, zircon Hf–O isotope analyses have also been carried out to decipher the nature of primary magma. Zircon U–Pb dating shows that the granodiorite porphyry and the granite aplite were emplaced at 269 ± 2 Ma and 270 ± 2 Ma, respectively, indicating the gold mineralization occurring no earlier than 269 Ma. Meanwhile, molybdenite veins are developed within the fractures and commonly cut across the auriferous veins. Thus, combined with a molybdenite Re–Os isochron age of 268 ± 1 Ma, the gold mineralization in the Bilihe deposit can be precisely restricted to ca. 269 Ma. Zircon ε Hf (t) values are mostly positive (1.6–11.3), along with high δ18O values of 6.20–7.63‰, suggesting a mixed source between mantle materials and ancient continental crust (such as the Bainaimiao Group) for the Bilihe magma. It is also supported by the presence of the captured detrital zircons in these intrusions. Given a universally metallogenic environment for porphyry gold deposits, a thicken crustal setting related to the collisional intermission of the Paleo-Asian Ocean is favored to interpret the formation setting of the Bilihe deposit. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Ore-forming fluids are moderate-high temperature and salinity, and relatively oxidized, and they evolved from magmatic to meteoric in origin. • Ore-forming materials were mainly derived from magma. • Temperature, redox, pH, and fluid-rock interaction are important controls on the transportation and precipitation of sulfides. Abstract The Tuwu porphyry copper deposit is located in the Eastern Tianshan Mountains, Xinjiang, China. Lentiform-like ore bodies are hosted in the Early Carboniferous Qi'eshan group, and Cu mineralization shows a close association with tonalite porphyry. Porphyry and country rocks have undergone extensive potassic, chlorite-sericite, phyllic and propylitic alteration. The mineralized veins in the Tuwu deposit can be divided into: earlier quartz–biotite ± magnetite ± chalcopyrite veins (stage I), quartz–chalcopyrite ± bornite ± pyrite veins (stage II) and quartz ± molybdenite ± chalcopyrite ± pyrite ± calcite veins (stage III), and later calcite ± quartz veins (stage IV). The Stage II and III are the main Cu mineralization stages. At the Tuwu deposit, three types of fluid inclusions have been distinguished: liquid-rich (L-type), vapor-rich (V-type) and halite-bearing (S-type), respectively. Laser Raman spectra identified magnetite, hematite, chalcopyrite, and pyrite at S-type inclusions. The quartz veins in stage I and II contain all inclusion types. L-type and V-type inclusions are recognized in stage III quartz minerals, but only L-type inclusions are present in stage IV quartz minerals. Fluid inclusions in quartz of stage I, II, III and IV are characterized by homogenization temperature vary of 275–492 °C, 232–477 °C, 199–287 °C and 133–227 °C, with corresponding NaCl equiv. salinities of 2.2–58.7 wt% NaCl equiv. , 1.4–58.3 wt% NaCl equiv. , 1.1–6.0 wt% NaCl equiv. , and 1.1–4.2 wt% NaCl equiv. , respectively. Initial ore-forming fluids of the Tuwu deposit belong to relatively oxidized H 2 O-NaCl system with moderate-high temperature and salinity. Sulfur isotope data from chalcopyrite and pyrite suggest a magmatic source. Two types of chlorite (type 1 and type 2) are recognized based on the relationship with metal sulfides. Electron microprobe analysis shows that chlorites are plotted in ripidolite and pycnochlorite. Decreasing Fe/(Fe + Mg) ratios of chlorites indicate that the meteoric water was involved in the magmatic water, combined with the positive correlation with AlIV, implying that the chlorite formed in a relatively reduced and acidic environment. The hydrothermal fluids in type 1 chlorite bring large quantities of reduced metallic minerals compared to the barren fluids in type 2 chlorite. The formation temperatures of chlorite are roughly coincident with the results that obtained from fluid inclusion studies, which show a decrease trend. Changes in temperature, redox, pH, and fluid-rock interaction likely play an important role in the transportation and precipitation of metal sulfides of the Tuwu deposit. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The ore-related porphyry shows a mantle source with depleted Sr, Nd, Hf, and O isotopic features. • The Duobaoshan granitoids are derived from melting of a thickened juvenile mafic lower crust. • The Duobaoshan deposit was formed in a subduction-related arc setting. Abstract The Duobaoshan porphyry Cu deposit (2.37 Mt Cu @ 0.47%; 73.4 tons Au @ 0.144 g/t and 80,000 tons Mo @ 0.016%) is located in the eastern part of the Central Asian Orogenic Belt (CAOB). Mineralization mainly occurs in the granodiorite and Ordovician volcanic rocks, and SIMS zircon U-Pb dating indicates that the ore-forming granodiorite porphyry emplaced at around 477 Ma. In addition, whole-rock major and trace element compositions show that the granodiorite porphyry belongs to a high-K to medium-K calc-alkaline series and has an affinity of adakitic rocks with high Sr, and low Y and Yb. Granodiorite porphyry samples are enriched in large ion lithophile elements (LILE) and light rare earth elements (LREE), and are depleted in high field strength elements (HFSE) and heavy rare earth elements (HREE). Their geochemical natures show a high Ni content (average 45.5 ppm) and Mg# value (average 46). The granodiorite porphyry shows very low initial 87Sr/86Sr ratios (from 0.70279 to 0.70414) and low δ18O (mean = +5.38‰), very high ɛ Nd (t) values (mean = +4.7) and ɛ Hf (t) values (mean = +12.11), and very young two-stage Hf and Nd model ages (average 765 Ma and 827 Ma, respectively). Given that the ore-related intrusions are coeval with the high-Mg diorites and andesites in the region, it is proposed that both the ore-related granodiorite porphyry and granodiorite were derived from melting of a thickened juvenile mafic lower crust, which was induced by underplating of melts from a depleted mantle wedge above a subduction zone. A certain proportion of slab melts may also have been involved in the magmas that produced ore-related intrusions. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Granodiorites and MMEs of the Late Devonian Husite intrusion were derived from the mixing of felsic and mafic melts. • The Boluokenu metallogenic belt was in a continental-arc setting due to the slab roll-back of Paleo-Junggar plate. • MMEs within granitic rocks can be used for prospecting porphyry and skarn Cu-dominated polymetallic deposits. Abstract Many porphyry and skarn Cu (Fe, Mo, Au, Zn) deposits have been discovered along the western Tianshan Orogenic Belt within the Central Asian Orogenic Belt. Generally, these Cu polymetallic deposits are considered to be linked to porphyries that formed in an arc setting, e.g., in a continental magmatic arc and island magmatic arc, but an agreement on their source region has not been reached. The Husite granitic complex and associated Kekesala skarn Fe-Cu deposit from the Boluokenu metallogenic belt provide significant insights into a comprehensive study of the ore-forming porphyries in Boluokenu. The ore-forming porphyries are mainly granodiorites and belong to calc-alkaline and high-K calc-alkaline series. LA-ICP-MS zircon U-Pb dating on the granodiorites yields ages of 368 Ma. The trace element compositions of the granodiorites are characterized by enrichment in large ion lithophile elements (LILE) and light rare earth elements (LREE), depletion in high field strength elements (HFSE) and heavy rare earth elements (HREE), and slightly negative Eu anomalies and are similar to rocks that form in a continental arc setting. These rocks also show large variations in their ε Hf (t) (+4.1 to +9.7) and Mg# (38–69) values, alongside low Ba/Th (4–230) and high Th/Yb (3.77–7.41) and Th/La (0.21–0.71) ratios, suggesting that the granodiorite magma originated from the partial melting of mafic lower crust with a mantle wedge component and involved signals of subduction-zone sediments and fluids. The Husite mafic microgranular enclaves (MMEs) exhibit high Mg# (50–62), MgO (3.25–6.93 wt%) and low SiO 2 (48.8–59.5%) contents, with positive ε Hf (t) from +3.3 to +7.4. The zircon LA-ICP-MS U-Pb ages of the MMEs (373 Ma) indicate nearly coeval formation between the MMEs and HMPs during the Late Devonian. These features with the petrological and mineralogical characteristics (such as needle-like apatite and disequilibrium feldspar xenocrysts) suggest that the Husite MMEs formed from the mixing of felsic magma from the partial melting of mafic lower crust and mafic magma that was derived from mantle wedge, rather than restite, xenoliths or fractional crystallization of magma. Thus, the skarn Fe-Cu mineralization were probably related to hybrid intermediate-acid magma that is characterized by high water and oxygen contents and high sulfur fugacity. It can be inferred that the response to ongoing slab roll-back during the Junggar plate's subduction beneath the Yili Block, including the underplating of mantle-derived mafic magmas from the metasomatism of subduction-zone melts, led to the partial melting of the mafic lower crust to form felsic magma. Then, the continuous reaction between the mafic and felsic magmas further increased the Fe-Cu concentrations and was closely related to the subsequent Fe-Cu mineralization. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Vein and porphyry Mo-Cu deposits constitute individual mineralization centers. • The causative intrusion was the ∼248 Ma Baituyingzi monzogranite porphyry. • The two types of deposits are different in vein geometries and Mo/Cu ratios. • The differences were related to stress regimes, wall rock compositions and fluid characteristics. Abstract Although there are important implications for mineral exploration, the genetic links between porphyry Mo and peripheral Mo–Cu vein deposits remain unclear. To constrain their possible relationships, this paper studied hydrothermal veins, Ar–Ar geochronology, and O–H–S–Pb isotopes from three Mo–Cu deposits in the Baituyingzi district, NE China. Mineralization in the Baituyingzi district occurs as quartz stockworks (e.g., the Baituyingzi porphyry Mo deposit) surrounding the Baituyingzi monzogranite porphyry and 0.1–1.5 m wide quartz veins (e.g., the Kulitu and Baimashigou Mo–Cu deposits) along regional faults. Apart from the quartz unidirectional solidification textures (stage 1) observed at Baituyingzi, the sequence of hydrothermal activity at each deposit was similar (although with minor differences) and includes: stage 2, sulfide-barren and Cu-bearing quartz veins related to potassic alteration (e.g., K-feldspar, biotite, hematite); stage 3, Mo-bearing quartz veins with no obvious alteration; stage 4, pyrite-rich quartz veins related to quartz-muscovite-illite alteration; and stage 5, calcite-quartz veins representing late hydrothermal activity. 40Ar/39Ar plateau ages of muscovite from stage 4 demonstrated that hydrothermal activities in Baituyingzi (241.4 ± 1.4 Ma) and Kulitu (239.4 ± 1.2 Ma) were contemporaneous, consistent with earlier Re–Os ages, indicating that the three deposits were co-genetic in the Early Triassic. Moreover, similar fluid inclusion assemblages, homogenization temperature ranges (up to 500 °C) and O–H isotopic ratios (δ18O fluid = 4.14‰ to 7.89‰ and δD = −97‰ to −90‰, indicative of magmatic origin) of stage 2 veins, and δ34S values (0–3‰) and radiogenic lead isotope ratios of sulfide samples were identified from each deposit, further confirming that the three deposits belong to individual mineralized centers. Integrated with previous data, we consider that: (1) the Baituyingzi hydrothermal system formed during the intrusion of the ∼248 Ma Baituyingzi monzogranite porphyry, and (2) the different stress regimes (e.g., regional structures and local fluid pressures), wall rock compositions, and fluid characteristics (e.g., salinity) of initial fluid branches resulted in the formation of three hydrothermal deposits with different vein attitudes and Cu/Mo ratios. Thus, our study reveals that the Mo–Cu vein deposits can constitute individual mineralization centers of a porphyry system as a result of different fluid branches that evolved along individual T–P–wall rock routes. This finding is a novel supplement to the magmatic hydrothermal mineralization model and can provide guidance for the exploration of similar Mo–Cu vein deposits. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The CAMD is one of the most important porphyry-type deposit domains on earth. • CAMD porphyry deposits are associated with the evolution of three Paleo-oceans. • MASH and slab melting models can explain the genesis of some PCDs in the CAMD. • A new model involves 'enriched lower crust and relictic oceanic ridge subduction' • Melting of juvenile lower crust was essential for Mo mineralization. Abstract A series of porphyry-type Cu-(Mo)-(Au) deposits including some giant world-class deposits such as Kounrad, Aktogai, Kal'makyr, Oyu Tolgoi and Chalukou occur in the Central Asian metallogenic domain (CAMD). The outline of the CAMD almost overlaps with that of the Central Asian orogenic belt (CAOB), which is located between the East Europe, Siberia, Tarim and North China cratons. The CAMD comprises sparsely exposed tectonic slices of Precambrian high-grade metamorphic basement rocks that are sandwiched between Phanerozoic accretionary complexes and arc rocks. According to geological, metallogenic, geochronological and tectonic setting characteristics, the CAMD comprises three metallogenic provinces: (1) the Kazakhstan Cu-Au-Mo, (2) the Mongolia Cu-Au and (3) the Northeast China Mo-Cu metallogenic provinces. Early Paleozoic (∼490 to 440 Ma) and Late Paleozoic (∼330 to 295 Ma) large scale porphyry-type mineralization in the Kazakhstan metallogenic province is intimately associated with the evolution of the Central Tianshan–Yili–Northern Tianshan–Kokchetav–Chingiz Paleozoic arc system which was terminated by the late Permian closure of the western segment of the Paleo-Asian Ocean. In contrast, the ∼370 Ma and ∼240 Ma porphyry-type mineralization of the Mongolia metallogenic province is related to the Tuva–Mongolia arc collage system that was formed during the evolution of the Paleo-Asian Ocean in the Paleozoic and the Mongol–Okhotsk Ocean in the early Mesozoic. Furthermore, the Northeast China metallogenic province was affected by three distinct geodynamic processes that were associated with the Paleo-Asian, Mongol–Okhotsk and Paleo-Pacific Oceans during the Paleozoic (>250 Ma), the early Mesozoic (>200 Ma) and the late Mesozoic (200–90 Ma), respectively. Except for the Early Paleozoic Cu mineralization at Duobaoshan (∼480 Ma) and Bainaimiao (440 Ma), the porphyry-type mineralization of this metallogenic province is predominantly characterized by widespread Mesozoic Mo mineralization. In general, porphyry-type deposits of the CAMD have geological, structural, metallogenic, alteration and fluid characteristics, which are consistent either with those related to the oceanic subductional arc settings of the Circum-Pacific metallogenic domain or with those of the continental collisional environment in the Tethyan metallogenic domain. The involvement of highly oxidized intermediate to felsic magmas is fundamental for the formation of porphyry deposits. Even though the prevalent MASH and slab melting models can be employed to interpret the genesis of some porphyry Cu deposits in the CAMD, a here newly suggested model, which is based on 'pre-enriched mafic lower crust and the subduction of a relictic mid-oceanic ridge', is thought to explain the large scale copper mineralization in the Balkhash–West Junggar metallogenic belt of the Kazakhstan metallogenic province. Nevertheless, most of the porphyritic suites associated with the Mo deposits in the Northeast China metallogenic province have relatively depleted mantle-like neodymium and hafnium isotopic compositions, suggesting that the ore-forming granitic magma may have predominantly been derived from juvenile lower crust. Upwelling of asthenosphere may have triggered the melting of the lower crust during post-collisional extension subsequent to the closure of the Paleo-Asian Ocean in the Triassic, the subduction of the Paleo-Pacific ocean in the Jurassic and the thinning of the lithosphere caused by rollback of the Paleo-Pacific plate in the Cretaceous. Ancient crustal components were only locally found to have been involved in the magma source of several medium-large Mo deposits. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The Ce4+/Ce3+ ratios of zircon from ore-related intrusions show a positive correlation with the size of deposits. • The Ce4+/Ce3+ ratios of 300, 200 and 100 separate the intrusions into superlarge, large, medium and small-sized deposits. • ΔFMQ + 2 discriminates the intrusions associated with medium to superlarge-sized deposits from small-sized deposits. Abstract The East Xing'an–Mongolian Orogenic Belt (EXOB) in China hosts numerous porphyry Mo deposits that are associated with calc-alkaline granitic intrusions. Here we report the trace-element compositions of zircon grains from 11 intrusions collected from 8 porphyry Mo deposits in the EXOB: the superlarge-sized Daheishan and Luming deposits; the large-sized Aolunhua deposit; the medium-sized Kulitu and Yangchang deposits; and the small-sized Erbadi, Hashitu, and Longtoushan deposits. The results show a positive correlation between the Mo tonnage of each deposit and the zircon Ce4+/Ce3+ ratio of the ore-related intrusions. In addition, the Ce4+/Ce3+ ratio of zircon in ore-related intrusions is much higher than that of the associated barren rocks. The Ce4+/Ce3+ ratios of 300, 200 and 100 of zircon seem to separate the intrusions into superlarge-sized, large-sized, medium-sized and small-sized porphyry Mo deposits, respectively. Oxygen fugacity values of ΔFMQ +2 of ore-related intrusions discriminate the medium-sized to superlarge-sized Mo deposits from the small-sized deposits. The relationship between the scale of mineralization and oxygen fugacity suggests that the oxidation condition of the source magma played a critical role in the development of large-sized and superlarge-sized Mo porphyry systems in the EXOB. The zircon Ce4+/Ce3+ ratios of ore-related intrusions of the EXOB are similar to those of porphyry Cu deposits in the Central Asian Orogenic Belt and the Yulong copper belt, but much lower than those of the Chuquicamata porphyry Cu deposit in Chile. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The Dongbulage and the Taibudai deposits in the Great Xing'an Range, NE China formed at 164 Ma and 138 Ma, respectively. • Fractional crystallization triggered mineralization of Cu and Mo mineralization. • Water contents of magma played important role in Cu and Mo precipitation. Abstract The Dongbulage porphyry Mo-dominant and Taibudai Cu-(Mo) deposits are located in the central–southern Great Xing'an Range, Inner Mongolia, northeastern China, and are associated with granite porphyry and monzogranite intrusions, respectively. Re–Os isotope data for five molybdenite samples from the Dongbulage Mo deposit give a weighted mean model age of 164.3 ± 1.2 Ma, which is in accordance with a zircon U–Pb age of 164.5 ± 1.7 Ma for the host granite porphyry, indicating that the deposit formed at the end of the Middle Jurassic. The zircon U–Pb age of the Taibudai ore-bearing monzogranite is 137.9 ± 1.7 Ma, indicating that the deposit formed in the Early Cretaceous. Whole-rock geochemical data indicate that the Dongbulage granite porphyry and the Taibudai monzogranite are high-K calc-alkaline, and have REE patterned light rare earth elements (LREEs) enriched and heavy rare earth elements (HREEs) depleted. Both plutons show Ba, Nb, and Ti depletions on normalized trace element diagrams, and the Dongbulage granite porphyry shows strongly negative Eu anomalies which are absent in the Taibudai intrusion. The geochemical differences between the two intrusions suggest that the Dongbulage granite porphyry is the result of more advanced fractional crystallization, which led to the formation of a Mo-dominant deposit, whereas the lesser degree of crystal fractionation in the Taibudai monzogranitic magma resulted in the formation of a Cu deposit. The relatively listric-shaped REE patterns of Taibudai rocks suggest more hydrous parental magmas than that of Dongbulage rocks. Therefore, fractional crystallization and magma water content exert a significant control on the styles of mineralization (Mo- versus Cu-dominant) in the central–southern Great Xing'an Range. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Migration and precipitation of Cu, Mo, and Fe are influenced by Oxygen fugacity, fluid component and temperature variation. • Cu and Mo can be enriched during ductile deformation through the physical and chemical migration. • Ductile deformed units may have great potential for porphyry Cu (-Mo) deposit formation under magmatism involvement. Abstract Porphyry Cu deposits can be strongly deformed during subsequent tectonic evolution. To date, research pertaining to the deformation and the enrichment of mineralization in porphyry deposits has suffered from a paucity of proof. Here, we describe the diagnostic petrologic and geochemical signatures of the Yuleken porphyry Cu deposit from stages of metallogenic overprinting. The rocks studied in this work are from deformation-metallogenic structures that have (1) a distinguished metallogenic and tectonic evolution, (2) a three-layer, spatial, deformation-metallogenic structure, (3) distinguishably different fluid components within protomylonite, mylonite, and ultramylonite zones, and (4) variational geochemical characteristics of coexisting chalcopyrite and magnetite. Integrated sulfide and oxide mineral investigations pertaining to the mineral deformation and the trace element variation of the minerals chalcopyrite and magnetite in the Yuleken porphyry Cu deposit indicated that Cu and Mo can be enriched during ductile deformation through physical (analogous geochemical characteristics of chalcopyrite from different stages) and chemical migrations. The elemental variation of magnetite (magnetites from deformed stages have higher contents of Ti, V, Co, Mn, and Ga than those from other stages) and the variation of the fluid components within the protomylonite, mylonite, and ultramylonite zones reveal that the migration and precipitation of Cu, Mo, and Fe were influenced by oxygen fugacity, fluid components, and temperature variation. In conclusion, the arc-related porphyry deposits were able to become involved in the ductile deformation zone, inducing areas of Cu and Mo enrichment in theory. Units subjected to ductile deformation may have great potential for porphyry Cu (-Mo) deposit formation under the influence of magmatism. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The Beishan monzogranitic pluton was emplaced at 194.75 ± 0.81 Ma. • Molybdenite Re-Os dating defines an isochron age of 194.0 ± 2.0 Ma. • The Beishan monzogranite was derived from partial melting of juvenile lower crust. • Dongfengbeishan porphyry Mo deposit was related to westward subduction of the paleo-Pacific plate. Abstract The Dongfengbeishan porphyry Mo deposit is located to the southeast of the Lesser Xing'an Range–Zhangguangcai Range metallogenic belt in NE China. LA–ICP–MS zircon U–Pb dating of the Beishan monzogranite yields an age of 194.75 ± 0.81 Ma. Five molybdenite samples define a Re–Os isochron age of 194.0 ± 2.0 Ma, suggesting that mineralization was associated with emplacement of the Beishan monzogranitic pluton. Monzogranite samples are classified as high-K calc-alkaline and are relatively enriched in light rare earth elements, depleted in heavy rare earth elements, Nb, Ba, P, Sr, Ti, and Zr, and yield negative Eu anomalies. These characteristics are interpreted to record fractional crystallization of the parental magmas. Zircon ε Hf (t) values for Beishan monzogranite samples range from +8.2 to +15.9, and two-stage model ages (T DM2) range from 217 to 711 Ma, indicating that the parental magma was produced during partial melting of juvenile lower crust. Combined with previous studies, our data suggest that the Dongfengbeishan porphyry Mo deposit was associated with westward subduction of the paleo-Pacific plate in the Early Jurassic. [ABSTRACT FROM AUTHOR]

The Rongna Cu-(Au) deposit is a recently discovered giant low-grade composite porphyry-high sulfidation epithermal system in the Duolong ore district of central Tibet. We present zircon U-Pb ages, bulk-rock geochemical and Sr-Nd isotope data, as well as zircon Hf-O isotope data to constrain the petrogenesis of the Rongna granodioritic porphyry, on which the ore system is centered. Secondary ion mass spectrometry (SIMS) zircon U-Pb data for two samples yielded ages of 118.7 ± 0.9 Ma and 117.1 ± 0.9 Ma, respectively. The granodioritic porphyry is of high-K calc-alkaline and magnetite-series affinity, with enrichment of light rare earth elements (LREEs) and large-ion lithophile elements (e.g., Rb, Pb, and K), and depletion of high-field strength elements (e.g., Ta, Nb, and Ti), typical of the geochemical signature of arc magmas. The Rongna granodioritic porphyry has initial Sr isotopic ratios of 0.7060–0.7099, and ε Nd (t) values of −5.7 to −1.7 with T DM (Nd) of 983–1900 Ma. The zircons have relatively narrow Hf-O isotopic compositions (ε Hf (t) = +3.30– +6.43; δ 18 O = +5.94– +6.96‰), indicating the involvement of old crustal materials. Our data suggest that the Rongna granodioritic porphyry likely evolved by fractional crystallization from a hybrid magma of mantle-derived mafic melts and lower crustal felsic melts during a period of magmatic flare-up following flat-slab subduction. [ABSTRACT FROM AUTHOR]

In the East Qinling orogenic belt, central China, there are numerous Mo deposits with over 6 Mt Mo metal. The giant Nannihu, Shangfanggou and Yuchiling porphyry Mo deposits are hosted in porphyry stocks associated with the Heyu batholith, whereas the giant Donggou porphyry Mo deposit is hosted in a stock associated with the Taishanmiao batholith. Zircon grains from the Heyu batholith have concordant 238 U/ 206 Pb ages scattered from 150 ± 3 to 130 ± 2 Ma with an age interval of nearly 20 m.y., whereas ore-hosting granitic porphyry stocks from the Nannihu, Shangfanggou and Yuchiling deposits have 206 Pb/ 238 U ages ranging from 151 ± 1 to 135 ± 1 Ma, 143 ± 1 to 132 ± 1 Ma, and 143 ± 5 to 131 ± 5 Ma, respectively. It is likely that the Heyu batholith has a prolonged history of incremental assembly and the ore-bearing granitic porphyry stocks may have originated from the same magma reservoir and emplaced in different stages. Likewise, zircon grains from the Taishanmiao batholith have concordant 238 U/ 206 Pb ages spanning in a period from 130 ± 2 to 111 ± 3 Ma, whereas those from the Donggou granitic porphyry stock have 238 U/ 206 Pb ages ranging from 125 ± 2 to 110 ± 3 Ma, nearly coeval with the Taishanmiao batholith. The molybdenite Re-Os model ages for each deposit are coincident with relatively young zircon 238 U/ 206 Pb ages of the host stock, indicating that Mo mineralization is likely related to late-stage magmatism. Zircon grains from the batholiths and granitic porphyry stocks have ε Hf (t) ranging from −10 to −30, T DM 2 ages from 1.6 to 2.5 Ga and δ 18 O from +5.0 to +8.7‰, which are taken to suggest the involvement of the subducted continental crust of the Yangtze Block in the source. We thus propose that the extensive Mo mineralization in the East Qinling porphyry Mo belt is genetically related to the prolonged granitic magmatism in the Late Mesozoic and a Mo-rich source that was related to the subducted continental crust of the Yangtze Block stagnating beneath the southern margin of the North China Craton. [ABSTRACT FROM AUTHOR]

• Wulonggou porphyries include granodiorite and coeval quartz diorite. • Post-collisional magmas derived from subducted slab and overlying sediments. • Lower to upper crustal magmatic differentiation process demonstrated. • Sulfide saturation and subsequent volatile exsolution at the upper crust are crucial. Major controls on the generation of ore-forming magmas for porphyry Cu systems remain controversial. This study provides a comprehensive dataset for the Wulonggou porphyries, which host intrusion-related gold deposits without any porphyry-skarn Cu mineralization, in the eastern Kunlun Orogen to investigate the influence of magmatic sources and differentiation processes on ore-forming magmas. The Wulonggou porphyries have a parental magma of basaltic andesite in composition derived from the oceanic crust in a post-collisional setting, which supplied sufficient Cu to the transcrustal magma plumbing system. The first-type amphibole crystallized after spinel, olivine and clinopyroxene at the lower crust. Spinel crystallization resulted in a decreased oxygen fugacity responsible for the formation of monosulfide solid solution that locked some Cu at the lower crust. At the upper crust, crystallization of calcic plagioclase cores and clinopyroxene was followed by magnetite, biotite, the second-type amphibole, and the mantles of normally zoned plagioclase. Magnetite and sulfide inclusions in the second-, third-type amphiboles and in patchy zoned plagioclase indicate reduced oxygen fugacities as well as the magnetite crystallization and sulfide saturation. Volatile exsolution was suggested by Cl and F variations in the second-type amphibole. The copper contents of corresponding melts calculated from amphibole phenocrysts are similar to those of normal arc magmas. Copper-rich sulfide saturation and subsequent volatile exsolution at the upper crust favor Cu-Au mineralization whereas the countryrocks and structures prefer intrusion-related gold deposits. Upper crustal magmatic differentiation processes are important for the generation of ore-forming magmas in post-collisional and subduction settings where a thick crust exists. [ABSTRACT FROM AUTHOR]

The Paleocene-Eocene ore deposits in the Gangdese Metallogenic Belt, Tibet, are thought to have been formed during the main period of India-Asia continental collision. This paper reports the whole-rock major element, trace element, and Sr-Nd-Hf isotopic compositions and zircon trace element contents of volcanic and intrusive rocks from the Paleocene Yaguila skarn Pb-Zn-Ag deposit and adjacent Eocene Sharang porphyry Mo deposit in the central Lhasa terrane, Tibet. Geochemical signatures and Nd-Hf isotopic compositions indicate that the Yaguila Cretaceous rhyolitic rocks were formed by the melting of ancient continental crust, whereas the Paleocene causative granite porphyry may have resulted from the interaction between mantle-derived and crustal-derived materials when continental collision was initiated. The dramatic increase of ε Nd (t) values between emplacement of the granite porphyry and later porphyritic biotite granite suggests a greater involvement of mantle materials during the crystallization of the barren biotite granite stock. The post-ore Miocene granodiorite porphyry has a similar geochemical signature to the Sharang Miocene dykes, suggesting they were both generated from melting of enriched lithospheric mantle. Nd-Hf mixing calculations indicate an increasing contribution of mantle materials in Paleocene to Eocene intrusions, consistent with the regional tectonic model of Neo-Tethyan oceanic slab roll-back and break-off. Zircons from both the Yaguila and Sharang ore-related porphyries have higher Ce anomalies than those from the barren granitoids, suggesting that Mo mineralization was closely related to highly oxidized and differentiated magma. The fertile intrusions in the Yaguila-Sharang district contain Eu N /Eu N ∗ values from 0.3 to 0.6, higher than the non-mineralized intrusions. The processes of early crystallization of plagioclase and/or SO 2 -degassing from underlying magma can explain the observed negative Eu anomalies in zircon. [ABSTRACT FROM AUTHOR]

The Caosiyao giant porphyry Mo deposit is located in the Wulanchabu area of Inner Mongolia, within the northern North China Craton (NCC). It contains more than 2385 Mt of ore with an average grade of 0.075% Mo. In the Caosiyao mining district, Mo mineralization occurs mainly in a Mesozoic granite porphyry as disseminations and stockworks, with some Mo distributed in Archean metamorphic rocks and diabase as stockworks and veins. The host granite porphyry is composed of two different phases that can be distinguished based on mineral assemblages and textures: one phase contains large and abundant phenocrysts (coarse-grained), while the other phase is characterized by fewer and smaller phenocrysts (medium-grained). Zircon U–Pb–Hf analyses of the former phase yielded a concordant 206 Pb/ 238 U age of 149.8 ± 2.4 Ma with a 206 Pb/ 238 U weighted mean age of 149.9 ± 2.4 Ma and ε Hf ( t ) values ranging from −12.2 to 18.3, while the latter phase gave a concordant 206 Pb/ 238 U age of 149.0 ± 2.2 Ma with a 206 Pb/ 238 U weighted mean age of 149.0 ± 2.1 Ma and ε Hf ( t ) values ranging from −13.1 to 17.7. Five samples of disseminated molybdenite have a 187 Re– 187 Os isochron age of 149.5 ± 5.3 Ma with a weighted average age of 149.0 ± 1.8 Ma, whereas six veinlet-type molybdenite samples have a well-constrained 187 Re– 187 Os isochron age of 146.9 ± 3.1 Ma and a weighted average age of 146.5 ± 0.8 Ma. Thus, it is suggested that the Mo mineralization of the Caosiyao deposit occurred during the Late Jurassic (ca. 147–149 Ma), almost coeval with the emplacement of the host granite porphyry (ca. 149–150 Ma). The host granite porphyry is characterized by high silica (SiO 2 = 71.52–74.10 wt%), relatively high levels of oxidation (Fe 2 O 3 /FeO = 0.32–0.94 wt%) and high alkali element concentrations (Na 2 O + K 2 O = 8.21–8.76 wt%). The host granite porphyry also shows enrichments in U and K, and depletion in Ba, Sr, P, Eu, and Ti, suggesting strong fractional crystallization of plagioclase, biotite, and accessory minerals. These observations, together with high SiO 2 contents and a high differentiation index (DI = 89.04–92.44), indicate a strong differentiation of the granite magma. Based on geological, geochronological, isotope systematics, and geochemical studies, we propose, for the first time, a genetic model for the Caosiyao porphyry Mo deposit. Under a regional extensional setting caused by far-field tectonics related to the Paleo-Pacific subduction during the Late Jurassic, a series of geodynamic, magmatic, and ore-forming processes took place, including formation of multi-directional and multi-phase faults, emplacement of the granitic host rocks, and Mo mineralization. Highly silicic, highly oxidized, and alkali-rich granitic magma, derived from partial melting of old lower crust, intruded into the country rocks. This highly differentiated granitic magma and the exsolved ore-forming fluids, enriched in Mo, migrated upward and interacted with the wall rocks. Eventually, ore minerals precipitated in fractures, resulting in the extensive deposition of molybdenite. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Mikengshan-Qingxixiang-Yanbei igneous rocks were formed at 145–134 Ma. • The Yanbei Sn-bearing granite porphyries were derived from ancient crustal rocks. • Reduced redox state and ancient crustal sources benefit for Sn mineralization. A world-class Sn province in South China contains granite- and porphyry-related Sn deposits. In this paper, we investigate the source of Sn, based on a study of Early Cretaceous (145–134 Ma) ore-barren granites and granite porphyries, ore-barren rhyolites, and Sn-bearing granite porphyries in the Mikengshan (MKS)–Qingxixiang (QXX)–Yanbei (YB) area of South China. The ore-barren rhyolites have enriched whole-rock Nd and zircon Hf isotopic compositions [ε Nd (t) = − 9.1 to − 10.5; ε Hf (t) = − 5.9 to − 13.8]. The ore-barren granites and granite porphyries have A-type granite characteristics and less enriched Nd–Hf isotopic compositions [ε Nd (t) = − 4.9 to − 3.2; ε Hf (t) = − 6.0 to + 1.7] than the ore-barren rhyolites. The Sn-bearing granite porphyries have similar rare earth element and trace element patterns to the ore-barren rhyolites. In addition, they have similar Nd but less enriched Hf isotopic compositions [ε Nd (t) = − 8.9; ε Hf (t) = − 3.3 to + 0.4] compared with the ore-barren rhyolites. The average ΔFMQ values of the studied volcanic (–0.50) and intrusive (–0.21) rocks indicate reduced condition during magma evolution. We suggest that the ore-barren rhyolites were likely derived by partial melting of Paleoproterozoic to Mesoproterozoic crustal metasedimentary rocks and that the Sn-bearing granite porphyries were possibly formed by partial melting of Paleoproterozoic metasomatized mantle-derived crustal rocks. Whereas, the ore-barren granites and granite porphyries were likely generated by partial melting of a hybridized source consisting of ancient and late Mesozoic juvenile crustal rocks. We propose that the reduced redox state and ancient crustal sources played an important role for Sn mineralization in the MKS–QXX–YB area. [ABSTRACT FROM AUTHOR]

• Eocene-Oligocene (36–33 Ma) potassic felsic rocks occur in the Sanjiang Region. • Eocene potassic felsic rocks produced by partial melting of mafic rocks in a thickened lower crust. • Eocene magmatic activities caused by post-orogenic delamination of lithospheric mantle and asthenosphere upwelling in the Eocene. This study presents zircon U-Pb dating and Hf isotope, whole-rock geochemistry and Sr-Nd isotopes of the potassic felsic porphyries from western Yunnan in the Sanjiang Region. Zircon U-Pb dating reveals that quartz-monzonite porphyry, granite porphyry, and adakitic granite porphyry were emplaced during 36–33 Ma. Geochemical data show that quartz-monzonite and granite porphyries have enriched LREE ((La/Yb) N = 39–67)and depleted HFSEs (e.g. Nb, Ta, P and Ti), with weak Eu anomalies. Moreover, they display similar 87Sr/86Sr ratios of 0.7068–0.7070 and negative εNd(t) values of −6.7 to −5.4, with zircon εHf(t) values of −5.65 to 3.06. The adakitic granite porphyries have high Sr (1273–1377 ppm), low Y (9.2–10.7 ppm), and low Yb (0.9–1.0 ppm) contents and high Sr/Y (128–138) and (La/Yb) N (17.7–19.8) values, typical of adakite rocks. In addition, these adakitic granite porphyries possess negative whole-rock εNd(t) values −0.2 to −0.3 and positive zircon εHf(t) values 2.7–6.0, associated with low Mg#, MgO, Ni and Cr contents. These geochemical features suggest that three kinds of potassic felsic porphyries could be produced by partial melting of mafic rocks (e.g., amphibolite) in a thickened lower crust. Our data, combined with previous studies and regional geology, suggest that delamination of lithospheric mantle and asthenosphere upwelling beneath the Sanjiang Region, both contributed to Cenozoic magmatic activities. [ABSTRACT FROM AUTHOR]

The NWW-striking North Qilian Orogenic Belt records the Paleozoic accretion–collision processes in NW China, and hosts Paleozoic Cu–Pb–Zn mineralization that was temporally and spatially related to the closure of the Paleo Qilian-Qinling Ocean. The Wangdian Cu deposit is located in the eastern part of the North Qilian Orogenic Belt, NW China. Copper mineralization is spatially associated with an altered early Paleozoic porphyritic granodiorite, which intruded tonalites and volcaniclastic rocks. Alteration zones surrounding the mineralization progress outward from a potassic to a feldspar-destructive phyllic assemblage. Mineralization consists mainly of quartz-sulfide stockworks and disseminated sulfides, with ore minerals chalcopyrite, pyrite, molybdenite, and minor galena and sphalerite. Gangue minerals include quartz, orthoclase, biotite, sericite, and K-feldspar. Zircon LA-ICPMS U–Pb dating of the ore-bearing porphyritic granodiorite yielded a mean 206 Pb/ 238 U age of 444.6 ± 7.8 Ma, with a group of inherited zircons yielding a mean U–Pb age of 485 ± 12 Ma, consistent with the emplacement age (485.3 ± 6.2 Ma) of the barren precursor tonalite. Rhenium and osmium analyses of molybdenite grains returned model ages of 442.9 ± 6.8 Ma and 443.3 ± 6.2 Ma, indicating mineralization was coeval with the emplacement of the host porphyritic granodiorite. Rhenium concentrations in molybdenite (208.9–213.2 ppm) suggest a mantle Re source. The tonalities are medium-K calc-alkaline. They are characterized by enrichment of light rare-earth elements (LREEs) and large-ion lithophile elements (LILEs), depletion of heavy rare-earth elements (HREEs) and high-field-strength elements (HFSEs), and minor negative Eu anomalies. They have ε Hf ( t ) values in the range of +3.6 to +11.1, with two-stage Hf model ages of 0.67–1.13 Ga, suggesting that the ca. 485 Ma barren tonalites were products of arc magmatism incorporating melts from the mantle wedge and the lithosphere. In contrast, the 40-m.y.-younger ore-bearing porphyritic granodiorite is sub-alkaline and peraluminous. They are enriched in LREEs and LILEs, depleted in HFSEs, and show weak negative Eu anomalies. They display ε Hf ( t ) values of captured or inherited zircons in the range of +8.5 to +10.0, and younger two-stage Hf model ages of 0.78 Ga and 0.86 Ga, similar to those of ca. 485 Ma tonalite. The ca. 445 Ma zircons have ε Hf ( t ) values of −2.1 to +9.9, with two-stage Hf model ages of 0.75–1.27 Ga. Moreover, they have relatively high oxygen fugacity than that of the precursor barren tonalite. The ca. 445 Ma magmas at Wangdian thus formed in a subduction setting, and incorporated melts from the subduction-modified lithosphere that had previously been enriched by additions of chalcophile and siderophile element-rich materials by the earlier magmatism and metasomatism during the Paleo Qilian-Qinling Ocean subduction event. [ABSTRACT FROM AUTHOR]

The Zhibula Cu skarn deposit (19.5 Mt ore @ 1.64%), near the Qulong porphyry Cu–Mo deposit, is located in the Gangdese porphyry copper belt in southern Tibet. The deposit is a typical metasomatic skarn that is related to the interaction of magmatic-hydrothermal fluids and calcareous host rocks. Stratiform skarn orebodies are mainly distributed in the contact between tuff and marble in the lower part of the Jurassic Yeba Formation. Endoskarn zonations for an outward trend are observed in the granodiorite, which grade from a fresh granodiorite to a weakly chlorite-altered granodiorite, a green diopside-bearing granodiorite, and a dark red-brown garnet-bearing granodiorite. The Zhibula granodiorite and monzogranite have similar secondary ion mass spectrometry (SIMS) zircon U–Pb ages of 16.9 ± 0.3 Ma and 17.0 ± 0.2 Ma, respectively. They exhibit different fractional crystallization from granodiorite (SiO 2 = 64.8–69.3 wt.%) to monzogranite (SiO 2 = 72.3–76.8 wt.%). Both the granodiorite and monzogranite are characterized by high Al 2 O 3 (12.6–16.7 wt.%) and K 2 O (1.5–5.5 wt.%) contents, high Sr/Y (35–151) and La/Yb (19–48) ratios, and variable MgO (0.16–3.91) and Mg# (31–61) values. They display features of enrichment in large ion lithophile elements (LILEs, e.g., Rb, Ba, Sr, and K), depletion in high field strength elements (HFSEs, e.g., Nb, Ta, Ti, and P), and moderate negative Eu anomalies (δEu = 0.58–0.98). They show restricted in situ zircon Hf isotopic compositions (+6.7 to +8.8; only one sample is +4.5) and consistent δ 18 O values (+6.0‰ to +6.6‰). The geochemical data indicated that the Miocene Zhibula granitic intrusions formed by the magma that were characterized by high Sr/Y ratios and were derived from the partial melting of the thickened juvenile lower crust, which may have been metasomatized by the slab melts during subduction of the Neo-Tethyan oceanic crust and were induced by the convective removal of the thickened lithosphere. In addition, the Zhibula Cu skarn deposit and the Qulong Cu–Mo deposit form a significant porphyry–skarn ore system. [ABSTRACT FROM AUTHOR]

The Wunugetushan porphyry Cu–Mo deposit is located in the southeastern margin of the Mongol–Okhotsk Orogenic Belt and in the northwestern segment of the Great Xing’an Range, NE China. The orebodies of this deposit are mainly hosted in the monzogranitic porphyry stock and in contact with the granitic porphyry dyke and biotite granite batholith. The SHRIMP zircon U–Pb dating of the granitic porphyry dyke yielded ages of 201.4 ± 3.1 Ma (2 σ , MSWD = 1.5). These results indicate that the magmatism in the Wunugetushan area might have occurred at ca. 201 Ma in the early Jurassic, and that the mineralization age (ca. 181 Ma) of this deposit is later than the age of intrusive granitic porphyry in the area. Geochemically, the Wunugetushan granitoids belong to high-K calc-alkaline and shoshonitic series, enriched in K, Rb, Nd, and Pb, and depleted in Sr, Nb, Ti and P, with negative Eu anomalies. In situ Hf isotopic analyses of zircons using LA-MC-ICP-MS indicate that the ε Hf ( t ) values for zircons from a granitic porphyry sample vary from +2.4 to +11.8 and that the corresponding crustal model ages ( T DM C ) vary from 483 to 1088 Ma. The least-altered monzogranitic porphyry, granitic porphyry and biotite granite yielded relatively uniform ε Nd ( t ) values from −1.0 to +0.6 and low ( 87 Sr/ 86 Sr) i ratios ranging from 0.704387 to 0.708385. The geochemical and Sr–Nd–Hf isotopic data for the granitoids indicate that the source magma for these rocks could be derived from a juvenile lower crust. The δ 34 S values of sulfides show a narrow range (+0.76‰ to +3.20‰) similar to those of magmatic sulfur, further implying a lower crust origin. Based on the results of this study and the regional geodynamic evolution, it is proposed that the formation of the Wunugetushan deposit and associated granitoids should be linked to the southeastward subduction of the Mongol–Okhotsk oceanic plate beneath the Erguna Massif during the early Jurassic, and that the monzogranitic porphyry intrusions in Wunugetushan area probably provided important ore metals responsible for the large-scale Cu–Mo mineralization. [ABSTRACT FROM AUTHOR]

The Baishan molybdenum deposit is located in the eastern section of the Jueluotage tectonic belt, Eastern Tianshan. There is a granite porphyry intrusion beneath the Baishan Mo ore bodies discovered by recent exploration drilling, and the Cu–Mo minerals are widely distributed in the porphyry. The zircon LA-ICPMS U–Pb age of the granite porphyry intrusion is 228.1 ± 8.0 Ma, which is in coincidence with the age of Mo mineralization (227.7 ± 4.3 Ma). The granite porphyry intrusion is calc-alkaline and peraluminous. The magma was derived from a lower crustal source, it experienced distinct crystal fraction during its evolution, and the magma intruded in a Triassic compressional background, and was probably influenced by far-field effects of the Tethys system to the south. Based on the geological, geochemical and geochronological characteristics of the granite porphyry intrusion, we propose that there is probably a porphyry Cu deposit beneath the Baishan high-Re Mo deposit. [ABSTRACT FROM AUTHOR]

The Miocene Dalli porphyry Cu–Au deposit in the central part of Urumieh–Dokhtar magmatic arc is the first reported Au-rich porphyry Cu deposit in the Zagros orogenic belt. The Cu–Au mineralization is mainly hosted in diorite and quartz diorite intrusions, presenting as numerous veinlets in the altered wall rocks, with potassic, phyllic, and propylitic alteration developed. Based on the mineral assemblages and crosscutting relations of veinlets, hydrothermal mineralization–alteration occurred in at least three stages, characterized by veinlets of (1) Qtz + Kfs + Mag ± Ccp, (2) Qtz + Py + Ccp ± Bn ± Cv ± Cc and, (3) Qtz + Chl + Bt. The ore-bearing intrusions exhibit typical geochemical characteristics of subduction zone magmas, including LREE fractionated pattern, strong enrichment in LILE (Cs, Rb, Ba, Pb, and U), and depletion of HFSE, with marked negative Ti and Nb anomalies. The adakite-like ore-hosting porphyry intrusions are characterized by a systematic gradual decreasing and increasing of Y and Eu/Eu ∗ with increasing SiO 2 content, respectively. Moreover, they exhibit a significant increasing trend of Sr/Y with decreasing of Y, which indicates progressive hornblende fractionation and suppression of plagioclase fractionation during the evolution toward high water content of parental magma. A relatively flat HREE pattern with low Dy n /Yb n and Nb/Ta values may represent that amphibole played a more important role than garnet in the generation of the adakitic melts in the thickened lower crust. Based on the phase assemblages confirmed by detailed laser Raman spectroscopy analyses and proportion of solid, liquid, and gaseous components, five types of fluid inclusions were recognized, which are categorized as; (1) liquid-rich two phase (liquid H2O + vapor H2O ) (IIA), (2) vapor-rich two phase (vapor H2O/CO2 + liquid H2O ) (IIB), (3) high saline simple fluids (IIIA; liquid H2O + vapor H2O + Hl), (4) high saline opaque mineral-bearing fluids (IIIB; liquid H2O + vapor H2O + Hl + Hem + Ccp + Py) and (5) multi-phase type (IIIAB; liquid H2O + vapor H2O + Hl + Anh + Hem + Mag + Ccp). In early stage veins, the homogenization temperature of multiphase inclusions as high as 620 °C, with corresponding salinities of up to 75 wt.% NaCl equivalent represent the initial ore-forming fluids. From early to late stage veins, the gradual decrease of homogenization temperature of saline inclusions (IIIAB, IIIA, and IIIB) from 620 to 340 °C (corresponding salinities of 75–35 wt.% NaCl equivalent) may reflect fluid boiling and mixing of the early magmatic fluids with circulating groundwater. The common association of hematite and anhydrite daughter phases with the most primitive inclusions (IIIAB) in early-stage veins and the lack of CO 2 -bearing inclusions in the middle to late stage veins reveal CO 2 content and oxygen fugacity of the fluids was significantly decreased from early to main stage of sulfide mineralization (second generation of veins). It seems that magnetite crystallization and CO 2 -escape have a decisive role in oversaturation of S 2− and subsequent rapid and large-scale precipitation of sulfides in second generation of veins at the Dalli deposit. [ABSTRACT FROM AUTHOR]

The petrogenesis and tectonic setting of Early Cretaceous granitoids and their enclaves emplaced in the Gan-Hang Tectonic Belt are still controversial. Here, we investigate mafic microgranular enclaves (MMEs) and their host granite porphyry from the Furongshan caldera to elucidate magma mixing and crust–mantle interaction in the Gan-Hang Tectonic Belt. The Furongshan granite porphyry is characterized by enrichments of alkalis, REE, Zr + Nb + Ce + Y contents (averaging 377 ppm), and high zircon saturation temperatures (793–843 °C), suggesting A-type granitic affinities. The granite porphyry can be further classified as an A 2 subtype granite based on high Y/Nb ratios (averaging 1.37). Zircon cores from the Furongshan MMEs exhibit the same ε Hf ( t ) values (−10.0 to −3.0) and U–Pb ages (127–129 Ma) as zircons form the granite porphyry, implying that they were captured from the felsic magma as xenocrysts. Petrological and mineralogical characteristics (such as needle-like apatite and disequilibrium feldspar xenocryst) suggest that the Furongshan MMEs and host granite porphyry were formed by magma mixing rather than restite, xenolith or fractional crystallization of mafic magma. The Furongshan granite porphyry samples have initial 87 Sr/ 86 Sr ratios of 0.7073–0.7099 and ε Nd ( t ) values of −3.7 to −3.3, which are similar to those of the MMEs (0.7068–0.7077 and −3.2 to −2.9, respectively). Similar trace element and Sr–Nd isotopic compositions imply a high degree of geochemical equilibration between the granite porphyry and its MMEs, and hence intense magma mixing, although some element contents and zircons ε Hf ( t ) values differ due to high zircon closure temperature and rapid cooling of commingled magmas. A binary mixing model based on Sr–Nd isotopes indicates a contribution of ∼50% basaltic melt to the hybrid magma of the Furongshan granite porphyry. A compilation of Sr–Nd–Hf isotopic data of the granitoids and MMEs from the Xiangshan, Furongshan and Muchen areas suggest that the basaltic components in the hybrid felsic magma increased from 0–20% at ∼135 Ma to 50–60% during 127–112 Ma in the Gan-Hang Tectonic Belt. This is consistent with the observation that zircon ε Hf ( t ) values of these granitoids simultaneously increased from −10.0 to 0. This increased input of mantle-derived magma through time suggested progressively intensified crust–mantle interaction during the Early Cretaceous in Southeast China, which may have been a response to ongoing slab roll-back during paleo-Pacific plate subduction. [ABSTRACT FROM AUTHOR]

The Late Cretaceous Hongniu–Hongshan porphyry–skarn copper deposit is located in the Zhongdian area of northwestern Yunnan Province, China. Garnets from the deposit have compositions that range from Adr 14 Grs 86 to almost pure andradite (Adr 98 Grs 2 ) and display two different styles of zoning. The garnets are predominantly of magmatic-hydrothermal origin, as is evidenced by their 18 O fluid (5.4–6.9‰) and low D fluid (−142‰ to −100‰) values, both of which likely result from late-stage magmatic open-system degassing. Three generations of garnet have been identified in this deposit: (1) Al-rich garnets (Grt I; Adr 22–57 Grs 78–43 ) are anisotropic, have sector dodecahedral twinning, are slightly enriched in light rare earth elements (LREEs) compared with the heavy rare earth elements (HREEs), have negative or negligible Eu anomalies, and contain high concentrations of F. Fluid inclusions within these Al-rich garnets generally have salinities of 12–39 wt.% NaCl eq. and have liquid–vapor homogenization temperatures (Th) of 272–331 °C. The Grt I are most likely associated with low- to medium-salinity fluids that were generated by the contraction of an ascending vapor phase and that formed during diffusive metasomatism caused by pore fluids equilibrating with the host rocks at low W/R (water/rock) ratios. These garnets formed as a result of the high F activity of the system, which increased the solubility of Al within the magmato-hydrothermal fluids in the system. (2) Fe-rich garnets (Adr 75–98 Grs 25–2 ) have trapezohedral faces, and are both anisotropic with oscillatory zoning and isotropic. These second-generation Fe-rich garnets (Grt II) have high ΣREE concentrations, are LREE-enriched and HREE-depleted, and generally have positive but variable Eu anomalies. All of the Fe-rich garnets contain high-salinity fluid inclusions with multiple daughter minerals with salinities of 33–80 wt.% NaCl eq. Some of them show higher temperatures of halite dissolution (465–591 °C) than liquid–vapor homogenization temperatures (319–473 °C), and several Fe-rich garnets contain inclusion groups indicative of boiling. The Grt II are associated with high-temperature, hypersaline fluids that were segregated from magma at a depth of at least 5.6 km and reacted with carbonates at depths shallower than 2.0 km. (3) Al-rich garnet veins (Adr 14–60 Grs 86–40 ) contain allotriomorphic crystals, have lower HFSE (high field strength element) and REE concentrations than the other garnets, and have HREE-enriched and LREE-depleted patterns with small Eu anomalies that are typical of the majority of garnets. The Grt III most likely formed from residual metasomatic fluids. [ABSTRACT FROM AUTHOR]

The newly discovered porphyry Cu deposits in the South Qinling Belt (SQB) have not been well researched as compared with the large porphyry Mo province in the southern North China Block (S-NCB), and the origin of granitoids associated with porphyry Cu mineralization in the Zha-Shan district, SQB is poorly constrained. Here, we present detailed zircon U–Pb geochronological, whole rock elemental and Sr–Nd isotopic data for important Late Mesozoic granitoid stocks associated with porphyry Cu deposits in the Zha-Shan district; these data are used to constrain the age and the source of magmas that formed these granitoids, and implication of regional metallogeny. The new zircon LA-ICPMS U–Pb ages presented here indicate that the granitoids related to porphyry Cu system at Chigou, Beishagou, Shuangyuangou and Yuanjiagou developed at 148–144 Ma, 144 Ma, 145–144 Ma and 146 Ma, respectively. These rocks are high-K calc-alkaline I-type granitoids, which are enriched in large ion lithophile elements (e.g., Th, U, and Pb) and light rare earth elements, are depleted in Nb, Ta and Ti, characterizing by wide variations in initial εNd ( t ) (−3.8 to −9.5), and moderate radiogenic Sr isotopes (( 87 Sr/ 86 Sr) i = 0.7046 to 0.7093). These features indicate that the magmas that formed the granitoids related to porphyry Cu system in the Zha-Shan district formed as a result of variable degrees of mixing between crustal and metasomatic lithospheric mantle. The new zircon LA-ICPMS U–Pb ages in this study, combined with previous published data, suggest that regional-scale Late Jurassic to Early Cretaceous granitoid stocks, and associated porphyry Cu and Mo systems in both the S-NCB and SQB formed almost contemporaneously, with 147–139 Ma porphyry Mo deposits in the S-NCB and 148–145 Ma porphyry Cu deposits in the SQB. The Cu-related intrusions contained a greater contribution of lithospheric mantle component than the Mo-related intrusions in the East Qinling Orogeny. [ABSTRACT FROM AUTHOR]

Existing geochronological and geochemical data for the Early Carboniferous magmatic rocks in the eastern Tianshan, Xinjiang, have been interpreted in a variety of theories regarding petrogenesis and geodynamic setting. The proposed settings include rift, back-arc basin, passive continental margin, island arc, ridge subduction, and post-collisional environment. To evaluate these possibilities, we present new SHRIMP zircon U–Pb geochronology and geochemical data, whole-rock geochemical, Hf isotope, and S isotope data for tonalitic rocks and ores associated with the Tuwu porphyry copper deposit located in the center of the late Paleozoic Dananhu–Tousuquan arc, eastern Tianshan. SHRIMP zircon U–Pb dating indicates that the magmatic activity and thus associated copper mineralization occurred ca.332 Ma. The tonalitic rocks are calc-alkaline granites with A/CNK values ranging from 1.16 to 1.58; are enriched in K, Rb, Sr, and Ba; and are markedly depleted in Nb, Ta, Ti, and Th. They show geochemical affinities similar to adakites, with high Sr, Al 2 O 3 , and Na 2 O contents and La/Yb ratios; low Y and Yb contents; and slight positive Eu anomalies. In situ Hf isotopic analyses of zircons yielded positive initial ε Hf ( t ) values ranging from 6.9 to 17.2. The δ 34 S values of the ore sulfides range from −3.0‰ to +1.7‰, reflecting a deep sulfur source. Our results indicate that the paleo-Tianshan oceanic slab was being simultaneously subducted northward beneath the Dananhu–Tousuquan arc, and southward beneath the Aqishan–Yamansu arc during the Early Carboniferous. The Tuwu adakitic tonalitic rocks were derived from the partial melting of the subducted paleo-Tianshan oceanic slab, which was subsequently hybridized by mantle wedge peridotites. The slab-derived magmas have considerably high copper contents and are highly oxidized, thus leading to porphyry copper mineralization. Such Early Carboniferous tonalitic rocks that are widespread in the eastern Tianshan define a province with high potential for copper mineralization. [ABSTRACT FROM AUTHOR]

The Bangpu porphyry Mo–Cu deposit is a representative Mo-dominated deposit besides the Sharang porphyry Mo deposit in the Gangdese metallogenic belt. The Mo–Cu mineralization has a close relationship with the monzogranite porphyry and diorite porphyrite. We identify three stages during the ore formation: a pre-ore stage, a main-ore stage with Mo–Cu deposited dominantly, and a post-ore stage. In this study, He–Ar, H–O, S and Pb isotopic compositions of the Bangpu deposit were determined. Based on these determinations, integrated isotope geochemistry studies were performed to constrain the possible sources of the ore-forming fluids and metals. The 3 He/ 4 He and 40 Ar/ 36 Ar ratios of fluid inclusions exhibit a range of 0.12209–0.36370 Ra and 275.6–346.1, respectively. The 4 He and 40 Ar concentrations vary from 1.51 to 3.57 (10 −7 cm 3 STP g −1 ) and 0.49 to 9.31 (10 −7 cm 3 STP g −1 ), respectively. He–Ar isotopic compositions suggest dominantly crustal-derived fluid with minor amount of meteoric water in the main ore stage. The δ 18 O fluid and δD fluid values vary from −1.3‰ to 3.9‰ and −140.5‰ to −73.7‰, respectively, indicating that magma fluids mixed with meteoric water. The average δ 34 S value of the sulfides (0.3‰) in the main-ore stage is close to the ore-forming porphyries, indicating a magmatic source. The lead isotopic components of ore sulfides exhibit restricted ranges with 206 Pb/ 204 Pb, 207 Pb/ 204 Pb, and 208 Pb/ 204 Pb ratios of 18.450–18.728, 15.602–5.672, and 38.715–39.211, respectively and μ values in the range of and 9.46–9.58, indicating ore-forming metals of primarily an upper crust source with a small amount of mantle materials. Compared to the Bangpu deposit, the ore metals derived from mantle are even greater in the Jiama and Qulong deposits, which leads to Cu being the dominant mineralization in the Jiama and Qulong deposit. [ABSTRACT FROM AUTHOR]

Most porphyry deposits in the world occur in magmatic arc settings and are related to subduction of oceanic plates. A small proportion of porphyry deposits occur in intracontinental settings, however they are still poorly understood. Shujiadian, a newly-discovered porphyry Cu deposit, is located in the Middle–Lower Yangtze River Valley metallogenic belt and belongs to the intracontinental class. The deposit has classic alteration zones defined by a core of potassic alteration and local Ca-silicate alteration, which is overprinted by a feldspar-destructive alteration zone and cut by veins containing epidote and chlorite. Wallrocks of the deposit are unreactive quartz-rich sedimentary rocks. Three main paragenetic stages have been recognized based on petrographic observations; silicate stage, quartz-sulfide stage, and sulfide-carbonate stage. Quartz + pyrite + chalcopyrite ± molybdenite veins, and quartz + chalcopyrite + pyrite veins of the quartz-sulfide stage contribute most of the copper, and chalcopyrite + chlorite ± pyrite ± pyrrhotite ± quartz ± illite veins of the sulfide-carbonate stage also contribute part of the copper; all the mineralized veins are associated with feldspar-destructive alteration. Investigations on the fluid inclusions in Shujiadian indicate that the ore-forming fluids had four evolutionary episodes: immiscibility and overpressure in the silicate stage, boiling in the quartz-sulfide stage and mixing with meteoric water in the sulfide-carbonate stage. Sulfur and strontium isotope studies suggest that ore metals were mainly derived from magmatic–hydrothermal fluids, and combined with our study of fluid inclusions, we infer that decompression, changes in oxygen fugacity and sulfur content were the main factors that caused Cu precipitation. Compared with porphyry deposits in magmatic arc settings, there are some differences in the ore-bearing rock, alteration, and the composition of ore-forming fluids. [ABSTRACT FROM AUTHOR]

The Gangdese is a newly explored porphyry Cu ore belt in China. In fact, except for the porphyry Cu deposits there are a lot of other deposits, forming a polymetallic copper belt in the southern Gangdese (SG, i.e., southern Lhasa terrane) and Gangdese back–arc fault uplift belt (GBAFUB, also called Lungar–Nyainqêntanglha arc). The Gangdese polymetallic copper belt contains porphyry Cu(–Mo–Au), Cu–Au and Mo(–Cu), skarn Cu(–Mo–Au–W), Pb–Zn(–Ag), Fe(–Cu) and Mo–W, breccia-type and hydrothermal vein-type Pb–Zn(–Ag) deposits. The porphyry Cu–Au mineralization occurred at the Xiongcun area of SG during the Middle Jurassic (175–160 Ma) and was associated with island arc magmatism related to the northward subduction of the Neo–Tethyan oceanic slab. The Cretaceous (ca. 112 Ma) skarn Fe(–Cu) mineralization appeared at the Nixiong area of GBAFUB and was generated in a back arc extensional setting related to the Neo–Tethyan oceanic subduction beneath the Lhasa terrane. The Paleocene–Eocene (65–51 Ma) porphyry Mo(–Cu), skarn Mo–W, and skarn Pb–Zn(–Ag) deposits are located in the eastern part of GBAFUB and related to granitoids originating from the partial melting of the old crust with contributions from the mantle. In contrast, the Paleocene–Eocene (60–45 Ma) porphyry Cu, skarn-, breccia-, and hydrothermal-vein-type Pb–Zn(–Ag), and skarn Fe–Cu deposits at the Namling area were associated with granitoids derived from the partial melting of the mantle with some input of the old crust. The Oligocene (30–23 Ma) porphyry–skarn Cu–Mo–W–Au mineralization occurred at the Zedong area adjacent to north of the Indus–Yarlung–Zangbo suture zone in a post collisional setting. The intensified Miocene (21–13 Ma) porphyry–skarn Cu(–Mo–Au), and skarn–hydrothermal-vein-type Pb–Zn(–Ag) deposits formed in the SG, whereas the porphyry Mo(–Cu) and skarn–hydrothermal-vein-type Pb–Zn(–Ag) deposits formed in the GBAFUB. The porphyry Mo(–Cu) mineralization have more substantial contributions from the old crust, in addition to the mantle, than those with porphyry Cu(–Mo–Au) mineralization. The source region of the high Sr/Y intrusions associated with post collisional porphyry Cu(–Mo–Au) mineralization is probably the arc magmas that were generated at the subduction stage and have remained stalled at the boundary between the crust and mantle since the Neo–Tethyan Ocean closed. The early subduction of the Neo–Tethyan oceanic lithosphere played a crucial role in the generation of ore deposits formed in collisional and post collisional settings. Six minerogenic series (or groups) can be recognized in the Gangdese polymetallic copper belt: (1) Jurassic porphyry Cu–Au minerogenic series related to island arc magmatism, (2) Cretaceous skarn Fe(–Cu) minerogenic series in back arc extensional setting, (3) Paleocene–Eocene granitoids-related polymetallic minerogenic series in collisional setting, (4) Oligocene porphyry–skarn Cu–W–Mo–Au minerogenic series in post collisional setting, (5) Miocene Cu–Mo–Au–Pb–Zn–Ag minerogenic series related to granitoids with substantial contributions from the mantle in post collisional setting, and (6) Miocene Mo–Cu–Pb–Zn minerogenic series related to granitoids with significant contributions from the old crust in post collisional setting. During mineralization, some deposits underwent superimposed mineralization, such as the Jiru porphyry Cu deposit where the Eocene and Miocene porphyry-type Cu mineralization occurred. The minerogenic series can be applied to ore prospecting. For example, when either Pb–Zn(–A [ABSTRACT FROM AUTHOR]

The coexistence of aqueous fluid inclusions and silicate melt inclusions in quartz phenocrysts from porphyrites at the Bangpu porphyry Mo–Cu deposit, Tibet, China were examined to characterize the immiscibility processes during the magmatic to hydrothermal transition. The physical and chemical environment during crystallization of the magmas has been reconstructed on the basis of microthermometric experiments and trace element microanalysis. Compositions of melt and brine fluid phases are determined using Synchrotron radiation X-ray fluorescence analysis, SEM–EDS and Laser Raman spectroscopy analyses. Brine fluids were directly exsolved by a crystallizing melt, and the simultaneous entrapment of volatile-rich (brine fluid) and volatile-poor immiscible phases (silicate melt) occurred at 670–700 °C and 1.6–1.95 kbar when the magma had H 2 O contents between 5 and 6 wt% and crystal contents of 60–80%. A later low-density fluid with a higher Mo concentration exsolved after about 80–90% crystallization had occurred. This fluid contained significant concentrations of Cl, Na, K, Ca, Fe, Cu, Zn, Rb, and small amounts of Mn, Br and Pb. Immiscibility of magmatic fluids can lead to different metal partitioning behaviors between residual melt and volatile phases, which generate variable metal ratios. Copper was partitioned preferentially into the brine phase, in contrast to the behavior observed in other porphyry Cu deposits. Ore deposition by a dense brine could explain the partially deep Cu mineralization. Condensation of brine from a later low-density parental fluid could be an efficient mechanism to concentrate shallow Cu mineralization and broadly distributed Mo mineralization. The source of the Mo mineralizing fluids probably was a particularly large magma chamber that crystallized and fractionated at depth greater than upper continental crust level. [ABSTRACT FROM AUTHOR]

The southern Great Xing’an Range (SGXR), located in the southeastern part of Inner Mongolia, China, shows intense Mesozoic tectono-magmatic activity and hosts economically important polymetallic (Cu–Pb–Zn–Sn–Fe–Ag–Au–Mo) mineralization. Here, we present new zircon U–Pb ages, whole-rock geochemical data, Nd–Sr–Hf isotopic data and Re–Os ages for the Taibudai deposit in the SGXR. The Taibudai granitoids show high SiO 2 (70.62–72.13 wt.%) and alkali (Na 2 O + K 2 O = 7.04–8.60 wt.%) concentrations, low MgO (0.89–1.37 wt.%) and Al 2 O 3 (∼14 wt.%), ASI ratios <1.1 (0.94–0.97), LILEs (e.g., Rb) enriched, HFSEs (e.g., Nb, Ta, Ti, and P) depleted, and have low Sr and Yb concentrations, classifying these rocks as fractionated I-type granites. The Taibudai granitoids have negative ε Nd ( t ) values ranging from −2.2 to −1.6 and relatively low initial 87 Sr/ 86 Sr ratios from 0.70536 to 0.70581. In situ Hf isotopic analyses on zircons using LA–MC–ICP–MS show variable positive ε Hf ( t ) values ranging from +0.80 to +13.55, corresponding to relatively young two-stage Hf model ages from 801 to 942 Ma (excluding one spot). These mineralogical, geochemical, and isotopic features strongly suggest that the primary magmas of the Taibudai granitoids were derived mainly from the partial remelting of Neoproterozoic juvenile crustal material, with no remarkable modification through incorporation of continental or subduction-related material. Re–Os isotope analyses of molybdenite from the deposit yield an ore-forming age of 137.1 ± 1.4 Ma. Re contents range from 4.37 to 41.77 ppm, implying ore material components have a mixed crust–mantle origin. SHRIMP analysis of zircons show that the monzogranitic porphyry and biotite granite in the Taibudai deposit were formed at 137.0 ± 0.9 Ma and 138.3 ± 0.9 Ma, respectively, indicating a temporal link between granitic magmatism and Cu mineralization. This result, combined with the regional geology, tectonic evolution, and age data from the literature, suggests that the Early Cretaceous (∼140 Ma) was the peak metallogenic epoch for the Great Xing’an Range, and the mineralization in this period generally takes the form of porphyry, skarn, or hydrothermal polymetallic ore deposits in an active extensional continental margin environment. The Taibudai porphyry and associated mineralization provides a typical example of magmatism and metallogeny associated with a Paleo-Pacific plate subduction, continental margin, back-arc extensional setting. [ABSTRACT FROM AUTHOR]

Most large to huge porphyry Cu deposits (PCDs) are oxidized, making the Baogutu reduced porphyry Cu deposit (RPCD) a relative rarity. CH 4 -bearing ore-forming fluids formed at several hydrothermal stages, however, their source is still unclear. To address this issue, isotopic investigations of sulfide He–Ar–S and calcite C were conducted. Fluid inclusions hosted in sulfides (arsenopyrite, chalcopyrite and pyrite) showed 3 He/ 4 He ratios of 0.06–0.30 Ra (Ra is the 3 He/ 4 He ratio of air = 1.39 × 10 −6 ), 40 Ar/ 36 Ar of 311–405, 40 Ar ∗ / 4 He of 0.06–1.01, and F 4 He ratios of 902–11,074 (sample BGT-Py 2 yielded a ratio of 100), indicating a predominantly crustal source for the fluids with minor mantle input (less than 5%). The δ 13 C values of carbonate yielded a value of −7.8‰ ( n = 3), implying that CO 2 was probably sourced from mantle or juvenile lower crust. According to the restricted sulfide δ 34 S values, the total S isotopic composition of the hydrothermal system was estimated to be 0.0–0.5‰, suggesting that the sulfur was derived from mantle or lower crust magmatic source. According to the published granitoids Nd isotopic compositions at the Baogutu RPCD, fairly young T DM model ages (450–650 Ma) suggest that the granitoids were derived from partial melting of a juvenile basaltic lower crust. Thus, we propose that small proportion of mantle-derived fluids (less than 5%), probably rise up and then mix with the fluids of juvenile lower crust under an extensional tectonic setting, forming the mantle-derived Sr–Nd–Pb–S–C but crustal He–Ar isotopic compositions. [ABSTRACT FROM AUTHOR]

The Dongshanwan porphyry Mo–W deposit is located in the southern segment of the Da Hinggan Mountains of the eastern segment of the Central Asia Orogenic Belt. More than 95% of the mineralization occurs within the Dongshanwan granite porphyry, with a small part being hosted within quartz veins that crosscut the Late Permian strata. Zircon U–Pb age measurements indicate that the Dongshanwan granite porphyry has a 206 Pb/ 238 U age of 151.4 ± 0.8 Ma. Three molybdenite samples from the Dongshanwan deposit were selected for Re–Os isotope measurement to define the mineralization age of the deposit. These yielded Re–Os model ages of 149.3 ± 2.3 to 155.4 ± 3.3 Ma. Based on analyses of major and trace elements and Hf isotopes, the Dongshanwan porphyry is characterized by low Sr and high Y values, exhibiting strong negative Eu anomalies ( δ Eu = 0.01–0.04), indicating post-collisional (A-type) geochemical characteristics. The Hf isotopic composition of the Dongshanwan porphyry ( ε Hf( t ) = +5.5 to +9.2) indicates that both juvenile crustal sources and depleted mantle contributed to their origin. The regional geological setting, when combined with the geochemistry of the Dongshanwan porphyry, probably indicates that the granite porphyry derives from crustal root melting during lithospheric delamination in northeast China caused by the rollback of the paleo-Pacific plate. [ABSTRACT FROM AUTHOR]

The Daheishan giant porphyry Mo deposit is located at the eastern segment of the CAOB, NE China. The ore-bearing intrusion of Daheishan deposit is a Jurassic granitic complex that includes Changgangling biotite granodiorite, Qiancuoluo seriate granodiorite, and Qiancuoluo granodioritic porphyry. Mineralization consists of disseminated, breccia and veined types. The hydrothermal fluids show significant magmatic signatures, as evidenced by the hydrogen and oxygen isotopic compositions of quartz and sulfur isotopic characteristics of ores. Consistence of lead isotopic compositions of the sulfides and the Daheishan intrusive complex further indicate a close relationship between the mineralization and magma. The fluid inclusions in quartz comprise of predominant aqueous two-phase as well as gas-rich fluid inclusions and a small number of daughter mineral-bearing inclusions. The gas species in the fluid inclusions are H 2 O, CO 2 , N 2 , CH 4 , C 2 H 6 , Ar ∗ and minor H 2 S; the liquid compositions are SO 4 2 − , Cl − , Na + , K + , Ca 2+ and Mg 2+ . Raman spectroscopy on individual fluid inclusions reveals a main gaseous composition of H 2 O, minor H 2 S and CO 2 . The fluid system in Daheishan Mo deposit can be described as NaCl–KCl–H 2 O type. Fluid inclusion microthermometry reveals subsolidus homogenization temperatures for fluid inclusions in the magmatic quartz phenocrysts ( T h = 400–450 °C, salinities = ∼21 eq. wt.%), suggesting an obliteration of higher temperature history of the porphyry system by the superimposed processes. Most of the mineralization occurred at temperature range of 220–360 °C, or higher. The temperature and salinity decreased to 100–170 °C and 0–15 eq. wt.%, respectively, when the hydrothermal fluid activities were gradually ending. No distinct evolution pattern based on the homogenization temperature or stable isotopic analyses is observed among the different mineralization stages. Mineralization was supposed to be related to the multi-phased boiling of fluids, instead of the gradual cooling of fluids. Pressure may be more critical than temperature in controlling the precipitation of molybdenite. [ABSTRACT FROM AUTHOR]

The Duobaoshan ore field, a major center of metal production in Northeast China, is located in the northeast of the Xing’an–Mongolia Orogenic Belt (the eastern part of the Central Asian Orogenic Belt) and within the northern Greater Xing’an Mountains. Several types of ore deposits are mined in the Duobaoshan region, including the Duobaoshan and Tongshan porphyry copper–molybdenum deposits, the Sankuanggou skarn iron–copper deposit, and the Zhengguang epithermal gold deposit. Zircon grains from the Tongshan granodiorite and porphyritic granite yield laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) U–Pb weighted mean ages of 475.9 ± 0.8 Ma and 230.9 ± 0.9 Ma to 240.7 ± 0.8 Ma, respectively. The Re–Os isochron age of molybdenites from the Tongshan deposit is 473 ± 4 Ma. Because both field observations and petrographic analysis identified disseminated chalcopyrite, pyrite, and malachite in the porphyritic granite, the isotope dating indicates that the Tongshan deposit underwent at least two magmatic–mineralization events, during the Ordovician and the Triassic. Zircon grains from the metallogenic granodiorite of the Sankuanggou skarn deposit yield an age of 176.1 ± 0.3 Ma, and Re–Os dating of molybdenite gives an age of 173 ± 6 Ma, indicating a Jurassic event. Based on previous research and the new geochemical analysis presented in this study, it is inferred that the magmatism and mineralization of the Sankuanggou deposit were associated with the subduction of the Paleo-Pacific Plate. The Duobaoshan region has therefore experienced at least three major magmatic and mineralization events, during the Ordovician (470–480 Ma), the Triassic (230–240 Ma), and the Early Jurassic (170–180 Ma). [ABSTRACT FROM AUTHOR]

Highlights: [•] The Luming and Xulaojiugou deposits form a porphyry-skarn metallogenic system. [•] Early Jurassic is an important mineralization epoch in the Lesser Xing’an Range. [•] The primary magmas were derived from melting of a metasomatized depleted mantle. [•] The early Jurassic magmatism were related to subduction of the Paleo-Pacific Plate. [Copyright &y& Elsevier]

Highlights: [•] Sulfide-mineralized enclaves were found in andesite of the Tulasu epithermal gold ore cluster. [•] Both andesite and enclaves were generated from the same island-arc magma. [•] There is potential to find porphyry Cu–Au deposits at depth of the Tulasu basin. [ABSTRACT FROM AUTHOR]

Highlights: [•] The magmatism and mineralization in the deposit took place during ∼130–128Ma. [•] The source regions are not the NCC lower crust but might be the YC lower crust. [•] The source rocks were UHP eclogites with some Paleoproterozoic–Archean YC rocks. [•] The delamination had not taken place beneath the Qian’echong deposit when it formed. [ABSTRACT FROM AUTHOR]

Highlights: [•] Few studies have discussed the evidence of magma recharge at porphyry Cu deposit. [•] Elemental and Sr isotopic compositions of plagioclases indicate magma recharge. [•] A maximum crystal residence time of ∼300years is estimated by tracer diffusion. [•] Injection of more mafic magma may add Cu to the Baogutu magma chamber. [ABSTRACT FROM AUTHOR]