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Chlorite is present extensively in many types of deposits. The mechanism underlying the chemical variations in chlorite remains unclear. The Naruo porphyry deposit is a giant copper porphyry deposit in the Duolong ore district of Tibet. Chlorite, which is abundant in this deposit, has yet to be studied systematically; hence, we used principal component analysis (PCA) to assess the correlation between chlorite elements and various types of mineral deposits. We then conducted a preliminary investigation into its mineralogy and geochemistry to better understand its formation process and identify potential prospecting indicators. The PCA method proved effective in discerning two distinctive element signatures within the chlorite and categorising them into four deposit types: orogenic Au deposits, granite-type U deposits, and skarn-type Sn deposits that exhibit high FeOand low MgO distinguishing them from porphyry copper deposits. The chlorite in the Naruo deposit is classified as either early metasomatic (M-type), consisting mainly of clinochlore, or late hydrothermal (H-type), primarily consisting of clinochlore and chamosite. This classification suggests that H-type chlorite formed in a reductive environment conducive to Cu precipitation at medium temperatures (255°C-342°C). Al-Si and Fe-Mg substitutions were found to be the primary processes involved in its generation. Additionally, from the mineralisation centre outwards, there was an observed decrease in Si content as well as the Fe/(Fe+Mg) ratio in H-type chlorite, along with decreases in temperature, sulphur, and oxygen fugacity of allchlorites; conversely, increases were observed for Al content along with Mg and Mn elements in H-type chlorite. Chlorite is useful for exploring porphyry copper systems as an indicator mineral. [ABSTRACT FROM AUTHOR]

The Jiama deposit, a significant porphyry‐skarn‐type copper polymetallic deposit located within the Gangdese metallogenic belt in Tibet, China, exemplifies a typical porphyry metallogenic system. However, the mineral chemistry of its accessory minerals remains under‐examined, posing challenges for resource assessment and ore prospecting. Utilizing electron microprobe analysis and LA‐ICP‐MS analysis, this study investigated the geochemical characteristics of apatite in ore‐bearing granite and monzogranite porphyries, as well as granodiorite, quartz diorite, and dark diorite porphyries in the deposit. It also delved into the diagenetic and metallogenic information from these geochemical signatures. Key findings include: (1) The SiO2 content, rare earth element (REE) contents, and REE partition coefficients of apatite indicate that the dark diorite porphyry possibly does not share a cogenetic magma source with the other four types of porphyries; (2) the volatile F and Cl contents in apatite, along with their ratio, indicate the Jiama deposit, formed in a collisional setting, demonstrates lower Cl/F ratios in apatite than the same type of deposits formed in a subduction environment; (3) compared to non‐ore‐bearing rock bodies in other deposits formed in a collisional setting, apatite in the Jiama deposit exhibits lower Ce and Ga contents. This might indicate that rock bodies in the Jiama deposit have higher oxygen fugacity. Nevertheless, the marginal variation in oxygen fugacity between ore‐bearing and non‐ore‐bearing rock bodies within the deposit suggests oxygen fugacity may not serve as the decisive factor in the ore‐hosting potential of rock bodies in the Jiama deposit. [ABSTRACT FROM AUTHOR]

The Xiongcun Cu–Au ore district is in the southern middle Gangdese Metallogenic Belt, Tibet, and formed during Neo-Tethyan oceanic subduction. The Xiongcun ore district mainly comprises two deposits, the No. I and No. II deposits, which were formed by two individual mineralization events according to deposit geology and Re–Os isotopic dating of molybdenite. The No. I deposit is similar to a reduced porphyry copper–gold deposit, given the widespread occurrence of primary and/or hydrothermal pyrrhotite and common CH4-rich and rare N2-rich fluid inclusions. The No. II deposit, similar to classic oxidized porphyry copper–gold deposits, contains highly oxidized minerals, including magnetite, anhydrite, and hematite. The halogen chemistry of the ore-forming fluid from the No. I and No. II deposits is still unclear. Biotite geochemistry with halogen contents was used to investigate the differences in ore-forming fluid between the No. I and No. II deposits. Hydrothermal biotite from the No. I deposit, usually intergrown with sphalerite, is Mg-rich and classified as phlogopite and Mg-biotite, and hydrothermal biotite from the No. II deposit is classified as Mg-biotite. Hydrothermal biotite from the No. I deposit has significantly higher SiO2, MnO, MgO, F, Li, Sc, Zn, Rb, Tl, and Pb contents and lower Al2O3, FeOtot, Cl, Ba, Cr, V, Co, Ni, Y, Sr, Zr, Th, and Cu contents than the biotite from the No. II deposit. Hydrothermal biotites from the No. I and No. II deposits yield temperatures ranging from 230 °C to 593 °C and 212 °C to 306 °C, respectively. The calculated oxygen fugacity and fugacity ratios indicate that the hydrothermal fluid of the No. I deposit has a higher F content, oxygen fugacity, and log(fHF/fHCl) value and a lower log(fH2O/fHF) value than the hydrothermal fluid from the No. II deposit. The biotite geochemistry shows that the No. I and No. II deposits formed from different hydrothermal fluids. The hydrothermal fluid of the No. I deposit was mixed with meteoric waters containing organic matter, resulting in a decrease in oxygen fugacity and more efficient precipitation of gold. The No. I and No. II deposits were formed by a Cl-rich hydrothermal system conducive to transporting Cu and Au. The decreasing Cl, oxygen fugacity, and temperature may be the key factors in Cu and Au precipitation. Biotite geochemistry allows a more detailed evaluation of the halogen chemistry of hydrothermal fluids and their evolution within porphyry Cu systems. [ABSTRACT FROM AUTHOR]

Jiama is a giant, high‐grade porphyry copper system in the Gangdese metallogenic belt, Tibet. Multistage intermediate–felsic porphyries intruded in this deposit, some of which are strongly associated with copper‐polymetallic mineralization. These ore‐bearing porphyries include monzogranite, granodiorite, and quartz diorite porphyries. A new granite aplite dyke was found in the south of Jiama. Its age, genesis, and relationship with ore‐related magmatism are obscure. Here, its emplacement age and petrogenesis were determined using mineralogy, zircon U‐Pb dating, geochemistry, and Sr‐Nd‐Pb isotope studies. The zircon LA‐ICP‐MS U‐Pb age of the aplite dyke is 16.66 ± 0.21 Ma (n = 14, MSWD = 0.66), earlier than that of the ore‐bearing porphyries (∼15 Ma) in Jiama. Furthermore, the aplite exhibits high amounts of silicon (SiO2 = 73.39%–74.74%), potassium (K2O = 5.12%–6.61%), aluminum (Al2O3 = 14.25%–14.69%), and light/heavy rare earth elements (LREE/HREE = 12.12–16.19) as well as negative europium (δEu = 0.47–0.72) and weak negative cerium anomalies (δCe = 0.84–0.93). The aplite dyke is characteristic of metaluminous–peraluminous I‐type granite, which is rich in large‐ion lithophile elements (Rb, Ba, Th and U) and depleted in high‐field‐strength elements (Nb, P and Ti). The aplite dyke and ore‐bearing porphyries in the Jiama deposit are the results of a partial melting of the juvenile lower crust, according to whole‐rock geochemistry and Sr‐Nd‐Pb isotope data, but the dyke and ore‐bearing porphyries were emplaced from the same magma chamber at different times. Thus, the aplite dyke shows the composition of the early evolution stage of shallow magma in the Jiama deposit and is the product of rapid condensation and crystallization. [ABSTRACT FROM AUTHOR]

The Bangbule skarn lead‐zinc (Pb‐Zn) deposit (>1 Mt Zn + Pb) is located in the western Nyainqentanglha polymetallic metallogenetic belt, central Tibet. Lenticular orebodies are all hosted in skarn and developed in the contact zone between the quartz porphyry and carbonate strata of the mid Paleozoic Middle to Upper Chaguoluoma Formation as well as in carbonate and sandstone beds of the Upper Paleozoic Laga Formation. As a newly discovered skarn deposit, the geological background and metallogenesis of this deposit remain poorly understood. Detailed petrological, geochemical and geochronological data of the ore‐related quartz porphyry, helps constrain the mineralization age and contributes to discussion on the ore genesis of the Bangbule deposit. Both endoskarn and exoskarn are identified in the Bangbule deposit. From quartz porphyry to carbonate formation, the exoskarn is zoned from proximal garnet skarn to distal pyroxene skarn. Zircon U‐Pb dating results show that the quartz porphyry formed at 73.9 ± 0.8 Ma. Geochemical analysis results show that the quartz porphyry has high contents of SiO2 (71.40–74.94 wt%) and K2O + Na2O (3.76–8.46 wt%) with A/CNK values of 0.69 to 1.06. Besides, the quartz porphyry is enriched in large ion lithophile elements (LILEs) and light rare earth elements (LREEs) and have low εNd(t) (from –8.25 to –8.19) and high initial (87Sr/86Sr)i values (0.713611–0.714478). Major, trace elements and whole‐rock F concentration analysis results from the endoskarn samples show higher TFe2O3, MgO, CaO, Pb + Zn, W, Sn, Mo and F etc., and lower alkalis (K2O, Na2O, Sr and Ba) than those of fresh quartz porphyry, indicating that the early ore‐forming fluids were an Ca‐Fe‐F‐enriched fluid. Massive ore in the proximal skarn might be related to the high F content in the magma, which lowered the solidus temperature of the quartz porphyry magma and caused a lower temperature of the ore‐forming fluids, as well as facilitating the precipitation of sphalerite and galena. Based on the geochemical characteristics presented in this study, we propose that the ore‐related quartz porphyry was formed by partial melting of crust materials with some juvenile crustal component input. The partial melting of the middle‐upper crust after the initial enrichment of lead and zinc elements are important for the formation of Pb‐Zn deposits. The case study of the Bangbule deposit has proven that there is still a crust‐derived magmatic source region in the western segment of the central Lhasa terrane. Therefore, there is still great potential for Pb‐Zn mineralization and Pb‐Zn exploration. [ABSTRACT FROM AUTHOR]

The Mamupu skarn‐type Cu‐Au polymetallic deposit represents the first discovery of a medium deposit in the southern Yulong porphyry copper belt (YPCB), eastern Tibet. The Cu‐Au mineralization mainly occurs as chalcopyrite in breccia, within the plate‐like carbonate interlayer, being closely related to chloritization (e.g., chlorite, magnetite and epidote) and skarnization (e.g., diopside, tremolite and garnet). The ore‐related quartz syenite porphyry (QSP) and granodiorite porphyry (GP) were emplaced at 40.1 ± 0.2 Ma and 39.9 ± 0.3 Ma, respectively. The QSP of Mamupu is an alkaline‐rich intrusion, relatively enriched in LREE, LILE, depleted in HFSE, with no significant negative Eu and Ce anomalies, slightly high (87Sr/86Sr)i, low ∊Nd(t), uniform (206Pb/204Pb)i and ∊Hf(t) values, which indicates that the porphyry magma may be caused by both the mixing of metasomatized EM II enriched mantle and thickened juvenile lower crust. The QSP in the Mamupu deposit shares a similar genesis of petrology to other ore‐related porphyries within the YPCB. High oxygen fugacity and water content of the magmas are essential for the formation of porphyry and skarn Cu deposits. The QSP has similar high magmatic oxidation states and water content to the Yulong deposit, which indicates that the Mamupu has a high prospecting potential. Differences in the geological characteristics and scale of mineralization between the Mamupu and other YPCB deposits may be due to the different emplacement depths of ore‐related intrusions, as well as differences in the surrounding rocks. [ABSTRACT FROM AUTHOR]

In order to understand how the metallogenic process of porphyry deposit specifically and directly respond to regional uplifting and exhumation, we compiled previous fluid inclusion data of 32 porphyry deposits in China by recalculating the fluid trapping depths and trapping depth reduction magnitude from early to late mineralization stage veins. The data reveal that the average trapping pressure ratio (Ave TPE/TPL) between early‐ and late‐stage veins of the these deposits are 1.2–18.4, mainly in the range of 1.35–5.83, with average trapping pressure reduction (1–Ave TPL/TPE) from early‐ to late‐ stage veins are 17%–95%, and mainly in the range of 25%–83%. The fluid trapping pressure based mineralization depths most of the porphyry deposits in China had decreased from early to late vein stages by at least 450 m (900–5800 m predominant), or greater than 950 m when take the average depth reduction value, which is greater than the current gap between early‐ and late‐ stage veins of each deposit. We propose that the apparently greater mineralization depth reduction magnitude than the current elevation gaps between early and late veins are likely a consequence of syn‐mineralization uplifting and exhumation process that often occurs in porphyry systems. [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]

The Tiegelongnan deposit is a newly discovered super-large porphyry-epithermal Cu-(Au) deposit in the western part of the Bangong Co-Nujiang metallogenic belt, Tibet (China). Field geology and geochronology indicate that the porphyry mineralization was closely related to the Early Cretaceous intermediate-felsic intrusions (ca. 123-120 Ma). Various epithermal ore and gangue mineral types were discovered in the middle-shallow part of the orebody, indicating the presence of epithermal mineralization at Tiegelongnan. Potassic, propylitic, phyllic and advanced argillic alteration zones were identified. 40Ar/39Ar dating of hydrothermal biotite (potassic zone), sericite (phyllic zone), and alunite (advanced argillic zone) in/around the ore-bearing granodiorite porphyry yielded 121.1±0.6 Ma (1σ), 120.8±0.7 Ma (1σ) and 117.9±1.6 Ma (1σ), respectively. Five hydrothermal mineralization stages were identified, of which the Stage IV pyrite was Rb-Sr dated to be 117.5±1.8 Ma (2σ), representing the end of epithermal mineralization. Field geology and geochronology suggest that both the epithermal and porphyry mineralization belong to the same magmatic-hydrothermal system. The Tiegelongnan super-large Cu-(Au) deposit may have undergone a prolonged magmatic-hydrothermal evolution, with the major mineralization event occurring at ca.120-117Ma. [ABSTRACT FROM AUTHOR]

The Duolong area is the most important part of the Western Bangong-Nujiang Suture Zone porphyry Cu(Au) metallogenic belt, in Tibet, China. Here new detailed data are presented from LA-ICP-MS zircon U-Pb, whole-rock geochemical, and in-situ zircon Hf isotope analyses for igneous rocks in the large Naruo deposit (2.51 Mt of Cu and 82 t of Au) which is located ∼2 km NE of the Duolong (Duobuza and Bolong) super-large gold-rich porphyry copper deposit. We integrated our results with previous research of other porphyry deposits in the Duolong area and have identified the timing, geodynamic setting, and petrogenesis of the mineralization-associated magmatic events. Based on the measurements, the Duolong area porphyry Cu(Au) deposit formations are associated with Early Cretaceous intermediate-felsic magmatism, which is consistent with U-Pb zircon ages of 120 Ma. All the main intrusive rocks in the ore-concentrated area have similar lithogeochemical characteristics; they show a relative enrichment in both light rare earth elements (LREEs) and large-ion lithophile elements (LILEs: Rb, Ba, K, etc.) and relative depletion in both heavy rare earth elements (HREEs) and high field strength elements (HFSEs: Nb, Ta, Zr, Hf, etc.). Moreover, the granite porphyry shows positive εHf( t) values between 1.38-7.37 suggesting that magmas were potentially derived from the partial melting of a depleted mantle wedge that had been metasomatized by subducted slab-derived fluids or melts. This paper points out that the formation of the porphyry-epithermal Cu(Au) deposit in the Duolong area was dominated by northward subduction of the Bangongco Tethys Plate beneath the Qiangtang block in the Early Cretaceous (124-114 Ma), when the subducted oceanic crust reached 50-70 km underground and generated different degrees of phase transformation, which lead to a melt produced by dehydration of amphibole minerals, a metasomatized mantle wedge, and induced mantle partial melting that produced the magma. Those deposits occurred in a continental arc tectonic setting, which is similar to the continental margin arc environment of the ocean-continent subduction setting of the Andes metallogenic belt in South America. [ABSTRACT FROM AUTHOR]

The article offers information on the research "Construction of the Three-dimensional Model for Jiama Deposit, Tibet, and its Significance in Geological Study" by Tang Pan and colleagues. Topics discussed include copper-polymetallic porphyry deposit, the rock forming and ore-forming chronology, and the construction of a 3D deposit model by Micromine software. Also mentioned are the geological and mineralized model of the Jiama deposit, the porphyry orebody output, and dikes and apophysis.

The mechanisms triggering the emplacement of Cretaceous magmatic rocks related to Neo-Tethyan subduction in the southern Lhasa subterrane (SLT) remain controversial because geochronological, geochemical, and isotopic data from the Cretaceous magmatic rocks in the western portion of the SLT are lacking. This paper provides the first report indicating that the Dazhuqu hornblende gabbro and Xietongmen granite porphyry were generated in the Late Cretaceous (ca. 100 Ma and ca. 68 Ma, respectively) in the western portion of the SLT. The Dazhuqu hornblende gabbro is characterized by high MgO, Na2O, Cr, Co, and Mg# values, enrichment in light rare earth elements (LREEs) and large ion lithophile elements (LILEs), and depletion in high field strength elements with no Eu anomalies. The Xietongmen granite porphyry displays high SiO2, low MgO, Mg#, Cr, Co, and Ni, enrichment in LREEs and LILEs, flat heavy rare earth element (HREE) patterns and negative Eu anomalies. Zircons from the Dazhuqu hornblende gabbro and Xietongmen granite porphyry display high positive εHf(t) ranges from 11.79 to 14.91 and from 9.05 to 12.38, respectively. The Dazhuqu hornblende gabbro was produced by the partial melting of 12–15% garnet peridotite in the depleted mantle that was metasomatized by fluids released from the dehydrating subducted Neo-Tethyan oceanic slab. This magma was then emplaced at an upper crustal depth of 5.3–7.0 km. The Xietongmen granite porphyry was generated by the partial melting of underplated basaltic crust during the subduction of the Neo-Tethyan oceanic crust and formed in the presence of pyroxene, plagioclase, and minor hornblende in its magmatic source. In combination with previously published data from Cretaceous magmatic rocks in the SLT, our data suggest that the petrogenesis of the Dazhuqu hornblende gabbro was related to flat or low-angle slab subduction of the Neo-Tethyan oceanic crust during 109–97 Ma and that the formation of the Xietongmen granite porphyry was related to lithospheric delamination in the western portion of the SLT after ca. 68 Ma. [ABSTRACT FROM AUTHOR]

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

The Xiongcun district, a unique area where oxidized porphyry copper-gold deposits (OPCD) and reduced porphyry copper-gold deposits (RPCD) coexist, is located in the central part of the Gangdese porphyry copper belt (GPCB) in Tibet, China, and hosts the only known mineralization related to the Neo-Tethyan oceanic subduction. Apatite and zircon major and trace elements, in situ oxygen isotopes in zircon from fertile quartz diorite porphyry (QDP) of the No. I deposit, fertile hornblende quartz diorite porphyry (HQDP) of the No. II deposit, and barren hornblende quartz diorite porphyry with coarse quartz eyes (QQDP) in the Xiongcun district were determined by EPMA, LA-ICP-MS, and SHRIMP II ion microprobe to investigate the petrogenesis, magma oxidation state, and mineralization differences between the No. I and No. II deposits, as well as the potential of apatite as a metallogenic indicator. The results from this study show that a combination of REE, Ti, oxygen isotopes, and the Th/U ratios in zircon and REE as well as Sr in apatite can be used to track the magma compositions and crystallization histories in porphyry systems. Multiple indicators, including the apatite SO 3 content, apatite Mn oxybarometer, and zircon Ce 4+ /Ce 3+ ratio, indicate that (1) the parental magmas of fertile QDP and HQDP containing Cu and Au mineralization were more reduced than that of barren QQDP; (2) despite barren QQDP having higher oxygen fugacity than QDP and HQDP, the lower Cu and water contents in the magma result in a lower potential for ore formation; and (3) the similar oxidation states of QDP and HQDP show that the mineralization differences between RPCD (No. I deposit) and OPCD (No. II deposit) were not caused by the oxidation states of the magmas but were likely caused by the different processes of hydrothermal fluid evolution. Apatite grains from fertile porphyries (QDP and HQDP) have much higher Cl/F ratios than those from barren porphyry (QQDP), indicating that the Cl/F ratio of apatite can be used as a proxy for porphyry Cu-Au mineralization related to the Jurassic porphyry intrusions in the Gangdese porphyry copper belt. [ABSTRACT FROM AUTHOR]

The Zegulangbei deposit develops a complete porphyry metallogenetic system, whose magmatic emplacement and mineralization was similarly related to an isolated apophysis derived from a uniform shallow magmatic chamber as the Main deposit. Jiama is a complex porphyry metallogenetic system composed of several isolated magmatic-hydrothermal centers. Multi-types of mineralization and alteration coexist among these metallogenetic centers, partially overlapped, developed with complicated and various metallogenic elements. [Display omitted] • Geological features of Zegulangbei deposit were identified in the Jiama ore district. • Precise geochronology redefine the magmatism, alteration and mineralization age. • Main deposit and Zegulangei deposit have originated from the same magma source. • Jiama is a polycentric, complex porphyry mineralization system. Jiama is a typical giant-scale collisional-type porphyry mineralization system of in the Gangdese metallogenic belt, Tibet. The Zegulangbei deposit is located in the northern part of the ore district, which was a recent discovery. In the Zegulangbei deposit, intrusions have developed in multiple stages and led to the formation of complex porphyry intrusions (2# porphyries), of which granodiorite porphyry and Ⅱ-quartz diorite porphyry occurred related to mineralization. Hydrothermal alteration surrounding the 2# porphyries is characterized by potassic, phyllic, and chlorite–sericite alteration, with minor propylitization, argillization and tourmalinization. Furthermore, veinlet-disseminated copper and molybdenum mineralization mainly occurred within the potassic and phyllic alteration zones. Partial copper mineralization developed within the chlorite–sericite alteration zone. The mineralization is comprised of porphyry Cu–Mo, hornfels Cu–Mo and skarn Cu–polymetallic ore bodies. Hydrothermal vein system developed well, including 5-staged veins (M-, A-, B-, C-, and D-type vein). The similar ages of intrusive rocks (15.8–14.5 Ma, U–Pb), biotite and sericite alteration minerals (15.04–15.02 Ma, 40Ar–39Ar), and molybdenite (14.9 Ma, Re–Os) indicate that the intermediate–felsic magmatic rock emplacement triggered the hydrothermal alteration and mineralization in the Zegulangbei deposit. Geochemistry and Sr–Nd–Pb isotopes of the intrusions in Zegulangbei are consistent with those of the intrusions in the Main deposit (1# porphyries) and the Miocene adakites that developed in the eastern Gangdese belt, implying they were generated from the partial melting of the thickened phlogopite-bearing juvenile crust that had been reworked by diapirs of the arc magma during subduction. The evidence presented in this study suggests that Zegulangbei developed a complete porphyry Cu–polymetallic mineralization system, which was related to the same magma chamber in the upper crust that caused the mineralization in the Main deposit. [ABSTRACT FROM AUTHOR]

We report the copper isotopic composition of Cu sulfides in the Tiegelongnan high-sulfidation (HS) copper deposit, Tibet, and investigate the possible application of Cu isotopes to mineral exploration. The copper isotopic values of samples from four drill holes display consistent progressive increase with depth to 400 m below surface, with an overall variation of δCu of up to 7.60‰ (−4.76 to 2.84‰). Such a large range is very different from that observed in Cu porphyry deposits which commonly exhibit a small δCu range (<1‰), with decreasing values with depth. The large δCu variation is likely of supergene origin and reflects strong leaching under oxidized conditions. The systematic increase of δCu with depth can be explained by the release of isotopically heavy Cu at the top and its transport downward, which is supported by the coupling of positive δCu values with high Cu grade and the occurrence of both negative and positive δCu values in two drill holes. Mass-balance consideration on the basis of Cu isotopes can indicate mineralized zones which have been eroded or have not been found yet. Such mineralized targets, if buried at depth, could be located using Cu isotopes. [ABSTRACT FROM AUTHOR]

The Jiama deposit, located in the eastern part of the well-known Gangdese Metallogenic Belt on the Tibetan Plateau, is the largest porphyry Cu–polymetallic system in the region, with the largest exploration budget, and is economically viable in the Gangdese Belt to undergo large-scale development. The deposit is well preserved and has experienced little erosion. The proven resources of the deposit are 7.4 Mt Cu, 0.6 Mt Mo, 1.8 Mt Pb + Zn, 6.65 Moz Au, and 360.32 Moz Ag. The results presented in this paper are based on geological and tectonic mapping, geological logging, and other exploration work performed by members of the Jiama Exploration Project Team over a period of 6 years. We propose that the Jiama porphyry Cu–polymetallic system is composed of skarn Cu–polymetallic, hornfels Cu–Mo, porphyry Mo ± Cu, and distal Au mineralization. The development of skarn Cu–polymetallic orebodies at the Jiama deposit was controlled mainly by the contact zone between porphyries and marbles, an interlayer detachment zone, and the front zone of a gliding nappe structure. The hornfels Cu–Mo and porphyry Mo ± Cu orebodies were controlled mainly by a fracture system related to intrusions, and the distal Au mineralization resulted from late-stage hydrothermal alteration. On the basis of field geological logging, optical microscopy, and chemical analysis, we verify that the alteration zones in the Jiama deposit include potassic, phyllic, propylitic, and argillic alteration, with a local lithocap, as well as endoskarn and exoskarn zones. The endoskarn occurs mainly as epidote alteration in quartz diorite porphyry and granite porphyry, and is cut by massive andradite veins. The exoskarn includes garnet–pyroxene and wollastonite skarn, in which the mineralogy and mineral chemical compositions display an outward zonation with respect to the source porphyry. From the proximal skarn to the intermediate skarn to the distal skarn, the garnet/pyroxene ratio varies from > 20:1 to ~ 10:1 to ~ 5:1, the garnet color varies from red-brown to brown-green to green-yellow, and the average composition of garnet varies from Ad 80.1 Gr 18.9 (Sp + Py) 1.0 to Ad 76.3 Gr 23 (Sp + Py) 0.7 to Ad 59.5 Gr 39.5 (Sp + Py) 1.0 , respectively. The pyroxene is not as variable in composition as the garnet, and is primarily light green to white diopside with a maximum hedenbergite content of ~ 20% and an average composition of Di 88.6 Hd 8.9 Jo 2.5 . From the proximal skarn to the intermediate skarn to the distal skarn, the mineralization changes from Cu–Mo to Cu ± Mo to Pb–Zn ± Cu ± Au ores, respectively. The wollastonite skarn displays no zonation and hosts mainly bornite mineralization. The Cu and Mo mineralization is closely related to the potassic and phyllic zones in the porphyry–hornfels. Zircons from four mineralized porphyries yield U–Pb ages of 15.96 ± 0.5 Ma, 15.72 ± 0.14 Ma, 15.59 ± 0.09 Ma, and 15.48 ± 0.08 Ma. The Re–Os ages of molybdenite from the skarn, hornfels, and porphyry are 15.37 ± 0.15 Ma, 14.67 ± 0.37 Ma, and 14.66 ± 0.27 Ma, respectively. The present results are consistent with the findings of previous research on fluid inclusions, isotopes, and other such aspects. On the basis of the combined evidence, we propose a porphyry Cu–polymetallic system model for the Jiama deposit and suggest a regional exploration strategy that can be applied to prospecting for porphyry-skarn mineralization in the Lhasa area. [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]

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]

Highlights: [•] The Xiongcun district present two middle Jurassic mineralizing episodes separated by 10m.y. [•] The porphyry mineralization in the Xiongcun district formed in island arc setting. [•] Four major metallogenic events existed in the Gangdese porphyry copper belt. [ABSTRACT FROM AUTHOR]

The article discusses the research study conducted to examine the genesis and main differences of Jiama and Qulong Super-Large Deposit in Gangdese metallogenic belt in Tibet, China and providing a necessary reference for regional deposit prospecting. It mentions that rocks including skarn, porphyry, and hornfels serve as main ore hosts in the Jiama deposit. It further mentions the difference in the mineral resource composition and useful element series and have a regional denudation.

The Lakang'e porphyry Mo (Cu) deposit, intermediate to large in size, is located in the eastern part of the southern Gangdese metallogenic belt. It is associated with a Miocene granodiorite porphyry (GDP). The alteration styles are mainly potassic and phyllic alteration, with minor argillic, chlorite, and carbonation alteration. In this study, we present whole-rock geochemical compositions, zircon LA-ICP-MS U-Pb data, zircon Hf isotope analyses, and zircon and apatite major and trace element compositions for the ore-bearing GDP and postmineralization quartz diorite porphyry (QDP) to constrain the formation of the Lakang'e Mo (Cu) deposit. The ore-bearing GDP, with a zircon U-Pb age of 13.83 ± 0.20 Ma, was intruded after mineralization by the QDP, which was emplaced at 13.00 ± 0.16 Ma. The GDP and QDP are high-K calc-alkaline series rocks with adakite-like features characterized by high contents of K 2 O and Al 2 O 3 , high Sr/Y ratios, strongly fractionated REE patterns, LILE enrichment, and HFSE depletion. The GDP and QDP have relatively low (87Sr/86Sr) i values (0.7051–0.7054) and high εNd(t) values (−0.87 to 0.59). Zircon grains from the QDP have high εHf(t) values (7.0–9.6), while zircon grains from the GDP show large εHf(t) variations ranging from −4 to 9.6, indicating that the magma source of the ore-bearing GDP included more continental crust than that of the postmineralization QDP. The zircon Ce4+/Ce3+ and Eu/Eu* ratios and apatite Mn and SO 3 contents indicate that the postmineralization QDP had higher oxygen fugacity than the ore-bearing GDP. The oxygen fugacity of the ore-bearing magma present during apatite crystallization (generally below the Ni-Ni-O (NNO) buffer), was lower than that present during zircon crystallization (above the hematite-magnetite (HM) buffer). The F, Cl, and S contents in apatite show that the GDP and QDP were F and S rich and that the GDP had a higher F content than the QDP. A high oxygen fugacity, a F- and S-rich magma and a Mo-rich crustal source were the key factors for the formation of the Lakang'e porphyry Mo (Cu) deposit. From Lakange Mo (Cu) deposit to Jiama Cu polymetallic deposit to Qulong Cu-Mo deposit to Xiongcun Cu-Au deposits, 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. Unlabelled Image • Geological features were identified in the Lakange porphyry Mo (Cu) deposit. • Precise geochronology redefines the magmatism and mineralization age. • High f O 2 , F- and S-rich and Mo-rich crustal source are favorable for mineralization. [ABSTRACT FROM AUTHOR]

The article offers information on the geological features of the porphyry deposit of Jiama in Tibet, China. Topics discussed include scientific and economic significance of Jiama porphyry at Gangdese metallogenic belt due to the presence of copper metal reserves, molybdenum, and silver reserves, Copper-Molybdenum ore found in bathy-hidden porphyry, and disseminated ore and veinlet ore as the main types of ores found in the porphyry.

The article discusses the zircon U-Pb LA-ICP-MS dating of ore-bearing biotite granite with an aim of understanding ore-related magmatism and its relation with the Bangongco-Nujiang metallogenic belt (BNMB). It states that zircons were separated from ore-bearing porphyry using heavy liquidand magnetic techniques. It is noted that the deposition of the Kuga copper was found in the eastern of the BNMB.

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]

Electron probe micro‐analysis (EPMA) and scanning electron microscopy (SEM) equipped with energy dispersive spectrometry (EDS) have been used to investigate the principal ore minerals and coexisting metallic mineral inclusions in polished thin sections from the Tiegelongnan deposit, which consists of a high‐sulfidation epithermal system (HSES) and a porphyry system (PS). Molybdenite, chalcopyrite, bornite, tennantite, enargite, digenite, anilite, covellite, and tetrahedrite have been identified by EPMA. Intergrowth, cross‐cutting and replacement relationships between the metallic minerals suggest that molybdenite formed first (stage 1), followed by chalcopyrite ± bornite ± hematite (stage 2), then bornite ± Cu‐sulfides ± Cu‐Fe‐sulfoarsenides (stage 3), and lastly Cu‐Fe‐ sulfoarsenides ± Cu‐ sulfides (stage 4). Pyrite is developed throughout all the stages. Droplet‐like inclusions of Au‐Te minerals commonly occur in tennantite but not in the other major sulfides (molybdenite, chalcopyrite and bornite), implying that tennantite is the most important Au telluride carrier. The pervasive binary equilibrium phases of calaverite and altaite constrain fTe2 in the range from ∼−6.5 to ∼−8 and fS2 < −11. The intergrowth of bornite and chalcopyrite and the conversion from bornite to digenite suggest fluctuated and relatively low precipitation temperature conditions in the HSES relative to the PS. Contrastingly, the dominance of chalcopyrite in the PS, with minor bornite, suggests relatively high temperature conditions. These new results are important for further understanding the mineral formation processes superimposed by HSES and PS systems. [ABSTRACT FROM AUTHOR]

The Baomai porphyry Cu-Mo deposit is a newly discovered deposit located in the northern section of the Yulong porphyry Cu belt, eastern Tibet. It is associated with Eocene biotite monzogranite intrusions that were emplaced into Paleoproterozoic Ningduo Group and Middle-Upper Triassic sedimentary rocks. A biotite monzogranite porphyry with a zircon U-Pb age of 42.7 Ma was intruded by several post-ore diorite porphyry dikes (ca. 37.8 Ma). Alteration mineral assemblages consistent with argillic, phyllic, and hornfels were identified in ore-bearing porphyries and host rocks at Baomai. Argillic and phyllic alteration assemblages are spatially related to high-grade Cu and Mo mineralization, whereas hornfels alteration is accompanied by weak Cu mineralization. Molybdenite from the mineralized porphyry returned a Re-Os isochron age of 42.6 Ma, and is considered to represent the age of porphyry-style mineralization at the deposit. Ore-bearing porphyries in Baomai are high-K (K 2 O/Na 2 O >1), alkaline-rich intrusions rich in LREE, LILE (e.g., Rb, U, K), depleted in HFSE (e.g., Nb, Ta, P and Ti) and contain absent or slightly negative Eu anomalies and no significant Ce anomalies. Slightly high 87 Sr/ 86 Sr ratios (0.7064–0.7076), low ε Nd(t) values (−2.5 to −4.6), uniform ( 206 Pb/ 204 Pb) i ratios (18.70–18.75) and positive ε Hf(t) values (0–5.3) of ore-bearing porphyries at Baomai indicate that they share the same or similar petrogenesis to other mineralized porphyries within the Yulong porphyry Cu belt. The porphyries were likely generated from partial melting of phlogopite-bearing amphibolite or amphibolite eclogite with a low degree of crystal fractionation, and related to enrichment mantle (EMII) transformed or mixed by older subducted slab-derived fluid. Actually, there are no significant three stages of ore-bearing magmatic activities in Yulong porphyry Copper belt (Hou et al., 2003b), Eocene intrusions (37–43 Ma) and regional strike slip faulting were all important factors in controlling the formation of these Cu-polymetallic deposits during the Eocene India-Tibetan collision. [ABSTRACT FROM AUTHOR]

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Highlights: [•] Chalcopyrite, bornite, pyrite and pyrrhotite are not low-level highly radiogenic. [•] No Re–Os isochron age of these sulfides is geologically meaningful. [•] Re–Os isotope system is sensitive and disturbed due to hydrothermal alteration. [ABSTRACT FROM AUTHOR]

The article focuses on the presence of Methane rich fluids in the No.1 porphyry copper-gold deposit in the Xiongcun district, and Gangdese porphyry copper belt in Tibet, China. Topics discussed include diamond drilling in Xiongcun completed by firm Tianyuan Minerals Exploration Ltd., the link between copper-gold mineralization and potassic alteration, and Raman spectroscopy used to detect gaseous composition of fluid inclusion in quartz.

The newly discovered Zhunuo porphyry Cu-Mo-Au deposit is located in the western part of the Gangdese porphyry copper belt in southern Tibet, SW China. The granitoid plutons in the Zhunuo region are composed of quartz diorite porphyry, diorite porphyry, granodiorite porphyry, biotite monzogranite and quartz porphyry. The quartz diorite porphyry yielded zircon U-Pb ages of 51.9±0.7 Ma (Eocene) using LA-ICP-MS, whereas the diorite porphyry, granodiorite porphyry, biotite monzogranite and quartz porphyry yielded ages ranging from 16.2±0.2 to 14.0±0.2 Ma (Miocene). Cu-Mo-Au mineralization is mainly hosted in the Miocene granodiorite porphyry. Samples from all granitoid plutons have geochemical compositions consistent with high-K calc-alkaline series magmatism. The samples display highly fractionated light rare-earth element (REE) distributions and heavy REE distributions with weakly negative Eu anomalies on chondrite-normalized REE patterns. The trace element distributions exhibit positive anomalies for large-ion lithophile elements (Rb, K, U, Th and Pb) and negative anomalies for high-field-strength elements (Nb and Ti) relative to primitive mantle-normalized values. The Eocene quartz diorite porphyry yielded ∊Nd( t) values ranging from -3.6 to -5.2, (87Sr/86Sr)i values in the range 0.7046-0.7063 and initial radiogenic Pb isotopic compositions with ranges of 18.599-18.657 206Pb/204Pb, 15.642-15.673 207Pb/204Pb and 38.956-39.199 208Pb/204Pb. In contrast, the Miocene granitoid plutons yielded ∊Nd( t) values ranging from -6.1 to -7.3 and (87Sr/86Sr)i values in the range 0.7071-0.7078 with similar Pb isotopic compositions to the Eocene quart diorite. The Sr-Nd-Pb isotopic compositions of the rocks are consistent with formation from magma containing a component of remelted ancient crust. Zircon grains from the Eocene quartz diorite have ∊Hf( t) values ranging from −5.2 to +0.9 and two-stage Hf model ages ranging from 1.07 to 1.46 Ga, while zircon grains from the Miocene granitoid plutons have ∊Hf( t) values from −9.9 to +4.2 and two-stage Hf model ages ranging from 1.05−1.73 Ga, indicating that the ancient crustal component likely derives from Paleo- to Mesoproterozoic basement. This source is distinct from that of most porphyry Cu-Mo-Au deposits in the eastern part of the Gangdese porphyry copper belt, which likely originated from juvenile crust. We therefore consider melting of ancient crustal basement to have contributed significantly to the formation Miocene porphyry Cu-Mo-Au deposits in the western part of the Gangdese porphyry copper belt. [ABSTRACT FROM AUTHOR]

The article reports on geological study of Pb-Zn deposits located in Narusonghuo, China. Topics discussed include several Pb-Zn mineralization formed by various physical processes chloritization, silicification and carbonation, found in the region, associated with quartz syenite porphyry, geochemical analysis on the same and role of Neo Tethys oceanic crust and wedge mantle in formation of Narusongduo porphyry magma, with characteristic chemical geology.

The article presents a study focusing on several tectonomagmatic events and mineralization process taking place in the Zhunuo Porphyry Copper (Cu)-Molybdenum (Mo)-Gold (Au) Deposit in South Tibet. Topics discussed include subduction of the Neo-Tethys oceanic crust leading to formation of magmatic arcs, association of continental magmatic plates with Porphyry molybdenum deposit and skarn deposit, and association of Miocene magmatism mineralization event with extension of Gangdese magmatic arc.

• CH 4 was generated by the thermal decomposition of the carbonaceous wall-rocks. • CH 4 added, which contributed to the system from oxidized to reduced conditions. • Ore elements were deposited via fluid boiling process. High f O 2 conditions characterize the majority of global porphyry copper deposits and contain highly oxidized minerals, such as magnetite and anhydrite. In contrast, the No. 1 porphyry Cu–Au deposit in the Xiongcun district (Tibet, China) has abundant pyrrhotite, reduced fluids (CH 4 ≫ CO 2), and a relative lack of highly oxidized minerals, which are indicative of low f O 2 conditions. Scanning electron microscopy, fluid inclusion, C–H–O–He–Ar isotopes, and whole-rock organic carbon contents and isotope analysis were used to constrain the evolution of ore-forming fluid, the origin of CH 4 and metal deposition mechanisms for the No. 1 deposit. The He–Ar isotopic compositions (3He/4He = 0.11–0.96 Ra, 40Ar/36Ar = 418.7–2920.2) suggest that the ore-forming fluids predominantly derived from crust source with minor mantle input. The H–O isotopic analysis results (δ18O H2O = −1.8 to +5.2‰, δD = −106 to −89.9‰) indicate that the ore-forming fluids were derived from a magmatic source that mixed with some meteoric waters. The element compositions of zircons and fluid/melt inclusions from the mineralized Middle Jurassic quartz diorite porphyry reveal that the primary magma was characterized by high log f O 2 (>NNO) conditions. The quartz diorite porphyry intruded into the carbon-bearing wall rocks produced abundant CH 4 by thermal decomposition of organic matter (δ13C CH4 = −26.3 to −28.5‰), which changed the redox state of the porphyry copper system from oxidized to reduced condition. Ore elements were deposited via fluid boiling as a consequence of the rapid decrease in temperature and pressure. [ABSTRACT FROM AUTHOR]

• Initial ore-forming fluids were low-salinity, CO 2 -rich, single-phase fluids. • The fluids evolved from magmatic in origin to meteoric water-dominated. • Fluid immiscibility was the prime factor resulting in chalcopyrite precipitation. • Fluid-cooling was probably responsible for molybdenite precipitation. The No. 2 porphyry Cu–Au deposit in the Xiongcun district forms part of the Gangdese porphyry copper belt of Tibet. This study clarifies the fluid evolution and ore precipitation mechanisms of the magmatic-hydrothermal system that formed the deposit by combining the results of fluid inclusion petrography, microthermometry, scanning electron microscope-cathodoluminescence imaging, and stable isotope analyses of multiple quartz-dominated veins. Four distinct sets of quartz-dominated veins and eight generations of quartz (Q1–Q8) within the veins were identified, namely from early to late, early barren quartz veins (V1) comprised of equigranular CL-bright Q1 quartz, quartz–pyrite–chalcopyrite ± magnetite veins (V2) containing early equigranular CL-bright Q1 quartz and later CL-gray or CL-dark Q2–3 (Q2 + Q3) quartz grains intergrown with Cu–Fe sulfides, quartz–molybdenite ± pyrite ± chalcopyrite veins (V3) comprised of quartz grains (Q4–Q6) characterized by subhedral comb-like textures with well-developed oscillatory growth zoning, and late quartz veins (V4) containing CL-gray Q7 quartz with euhedral growth zones and later CL-dark Q8 quartz. Fluid inclusions in these veins can be classified into six types: B40, B40H, B80, B15H, B15H+, and B15. The B40 and B40H inclusions; B80 inclusions; and B15, B15H, and B15H+ inclusions contain vapor bubbles occupying 30–60 vol%, >70 vol%, and 5–25 vol%, respectively; in addition, B15H, B15H+, and B40H inclusions contain transparent daughter minerals (halite, and in some cases, sylvite). Raman spectra showed that CO 2 is only present in B40 and B80 inclusions. In the Q1 quartz in V1 and V2 veins, the dominant type of inclusions is B40, which have homogenization temperatures (Th) of 278 °C–389 °C (peaking at 310 °C–330 °C) and salinities of 2.0–12.8 wt% NaCl equiv. In Q2–3 quartz in V2 veins, all inclusion types were observed. These were trapped at temperatures of approximately 325 °C–340 °C and had salinities of 1.8–69.7 wt% NaCl equiv. In V3 veins, only B15H and B15 inclusions were observed, which had Th values of 171 °C–320 °C (peaking at 240 °C–260 °C) and 173 °C–317 °C (peaking at 210 °C–230 °C) and salinities of 28.7–33.9 wt% NaCl equiv and 5.6–23.1 wt% NaCl equiv, respectively. In V4 veins, only B15 inclusions were observed. Primary B15 inclusions in V4 veins yielded Th values of 166 °C–229 °C (peaking at 170 °C–200 °C) and salinities of 5.1–17.1 wt% NaCl equiv. The 3He/4He and 40Ar/36Ar ratios of the fluid inclusions exhibited the ranges of 0.08–0.84 Ra and 451.3–1567.8, respectively, and the δ18O fluid and δD fluid values varied from −3.2‰ to 5.8‰ and −92.8‰ to −80.3‰, respectively. By integrating all results from the fluid inclusion, cathodoluminescence, and isotopic analyses, we conclude that the initial ore-forming fluids of the No. 2 deposit were low-salinity, CO 2 -rich single-phase fluids of magmatic origin. Subsequently, fluid immiscibility developed in the initial ore-forming fluids, generating hypersaline liquid and low-salinity vapor phases and leading to the separation of a CO 2 phase plus chalcopyrite precipitation from the fluids. As meteoric water was injected into the hydrothermal system, the ore-forming fluids gradually evolved to become meteoric water-dominated, low temperature, low-salinity, and CO 2 -poor; in addition, fluid-cooling due to the meteoric water input resulted in molybdenite precipitation. [ABSTRACT FROM AUTHOR]

The article presents a study that highlights mineralogical and petrographic characteristics of the Mengyaa lead (Pb)- Zinc (Zn) deposit in Tibet. The study shows that magmatic rocks in the deposit comprise granite porphyry, quartz porphyry and diabase porphyrite. Also the study reveals several minerals in the deposit including gangue minerals such as quartz and calcite, primary ore minerals such as pyrite and galena, and secondary minerals such as anglesite and goethite.

The article offers information on the research "The Curves of Seven REE and Their Geological Significances of Porphyry Mo (Cu) Deposit of Chengba, Tibet, China" by Song Xuebing and colleagues. It concludes that the curve types of seven rare earth elements (REE) which significance is clearly useful in determining the successions of intrusive, interpreting the genesis and evolution of magma as well as analyzing the process of mineralization.