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Multistage tungsten mineralization was recently discovered in the Mamupu copper‐polymetallic deposit in the southern Yulong porphyry copper belt (YPCB), Tibet. This study reports the results of cathodoluminescence, trace element and Sr isotope analyses of Mamupu scheelite samples, undertaken in order to better constrain the mechanism of W mineralization and the sources of the ore‐forming fluids. Three different types of scheelite are identified in the Mamupu deposit: scheelite A (Sch A) mainly occurs in breccias during the prograde stage, scheelite B (Sch B) forms in the chlorite‐epidote alteration zone in the retrograde stage, while scheelite C (Sch C) occurs in distal quartz sulfide veins. The extremely high Mo content and negative Eu anomaly in Sch A represent high oxygen fugacity in the prograde stage. Compared with ore‐related porphyries, Sch A has a similar REE pattern, but with higher ΣREE, more depleted HREE and slightly lower (87Sr/86Sr)i ratios. These features suggest that Sch A is genetically related to ore‐related porphyries, but extensive interaction with carbonate surrounding rocks affects the final REE and Sr isotopic composition. Sch B shows dark (Sch B‐I) and light (Sch B‐II) domains under CL imaging. From Sch B‐I to Sch B‐II, LREEs are gradually depleted, with MREEs being gradually enriched. Sch C has the highest LREE/HREE ratio, which indicates that it inherited the geochemical characteristics of fluids after the precipitation of HREE‐rich minerals, such as diopside and garnet, in the early prograde stage. The Mo content in Sch B and Sch C gradually decreased, indicating that the oxygen fugacity of the fluids changed from oxidative in the early stages to reductive in the later, the turbulent Eu anomaly in Sch B and Sch C indicating that the Eu anomaly in the Mamupu scheelite is not solely controlled by oxygen fugacity. The extensive interaction of magmatic‐hydrothermal fluids and carbonate provides the necessary Ca2+ for the precipitation of scheelite in the Mamupu deposit. [ABSTRACT FROM AUTHOR]

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]

Rubidium (Rb) deposits mostly occur in the South China and Central Asia orogenic belts and are often closely associated with highly differentiated granites. This study investigates a newly‐discovered giant Rb deposit at Gariatong in the Central Lhasa terrane in Tibet. Detailed field studies and logging data revealed that the Rb mineralization mainly occurs in monzogranite and is related to greisenization. LA‐ICP‐MS U‐Pb dating of zircon yielded ages of 19.1 ± 0.2 Ma and 19.0 ± 0.2 Ma for greisenized monzogranite and fresh monzogranite, respectively. The monzogranites are characterized as strongly peraluminous, with high contents of SiO2, Al2O3, K2O and Na2O as well as a high differentiation index. They are enriched in light rare earth and large ion lithophile elements with significant negative Eu anomalies and depleted high field‐strength elements. Petrological and geochemical features of these ore‐related monzogranites suggest that they are highly fractionated S‐type granites, derived from remelting of crustal materials in a post‐collisional setting. The geochemistry of zircon and apatite points to a low oxygen fugacity of the ore‐related monzogranite during the magma's evolution. The discovery of the Gariatong Rb deposit suggests that the Central Lhasa terrane may be an important region for rare metal mineralization. [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]

The Sinongduo mining region includes two types of mineralizations: the epithermal and the carbonate‐hosted Pb‐Zn‐Ag deposits. Despite being studied for many years, the ore formation process and genesis of the carbonate‐hosted Pb‐Zn‐Ag deposits remain poorly understood. The Pb‐Zn‐Ag ore bodies occur as veins and are hosted by limestone and dolostone of the Permian Xiala Formation. Three sulfide mineralization substages have been identified at the Sinongduo carbonate‐hosted deposit. Indium coupled with Cu, Co and Sn was incorporated into sphalerite as substitutions: 2Zn2+ ↔ Cu+ + In3+, (3n/2 + 1)Zn2+ ↔ Co2+ + nIn3+ or (2n + 1)Zn2+ ↔ Co2+ + n(Cu+ + In3+) (n > 1) and 4Zn2+ ↔ Sn2+ + 2In3+. Sphalerite and pyrite in the mineralization stage display δ34S values in a narrow range of +5.7‰ to +11.3‰, which are similar to those of Palaeocene igneous rocks, indicative of a magmatic source of sulfur. We present systematic carbon‐hydrogen‐oxygen isotope results that further support a magmatic source for the ore‐forming fluids that were influenced by meteoric water. Furthermore, the Pb isotope compositions of sulfide minerals in the Sinongduo carbonate‐hosted deposit overlap with the values of coeval Linzizong volcanic rocks and are similar to those of Indian Ocean sediments, indicating upper crustal sources of metals. We conclude that the Sinongduo carbonate‐hosted Pb‐Zn‐Ag deposit is a medium‐ to low‐temperature magmatic‐hydrothermal deposit related to Linzizong magmatism. [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]

We evaluate the controlling factors of hydrothermal wolframite and scheelite precipitation in the quartz vein-type Jiaoxi tungsten deposit situated in the western part of the Lhasa terrane (Tibet, China) using texture, major and trace element mineral geochemistry, and sulfur stable isotope geochemistry. Pyrite and chalcopyrite that are intergrown with Fe-enriched wolframite and siderite, have distinct in situ S isotope compositions (δ34SV-CDT) of −31.38 to +1.77‰, and +2.07 to +2.30‰, respectively. Major and trace element contents and in situ S isotope compositions of pyrite and chalcopyrite indicate that the hydrothermal evolution involved fluid-fluid mixing and greisenization. We report evidence for an early magmatic fluid, which is characterized by the enrichment of W, Mn, Zr, Ti, Sc, and Sn and depletion of Fe. This magmatic fluid was diluted by meteoric water and interacted with biotite monzogranite porphyry to leach Fe, Mg, and Zn into the system to form wolframites with variable Fe/(Fe+Mn) ratios ranging between 0.06–0.84. The late Fe-enriched magmatic fluid released from the muscovite granite mixed with meteoric water that leached minor Fe and S from shale to form late shale-hosted wolframite with a Fe/(Fe+Mn) mass ratio of >0.75 and coeval siderite and sulfides. This study highlights that multiple Fe sources were present in the system, including muscovite granite-released Fe through fluid exsolution, biotite monzogranite porphyry-released Fe during greisenization, and minor Fe released from the shale as a result of meteoric water leaching. [ABSTRACT FROM AUTHOR]

The subduction of the Bangong–Nujiang Ocean is important in the geological evolution of the Tibetan Plateau. In this paper, we report new zircon U-Pb age and Lu-Hf isotopic data and whole-rock elemental and Sr-Nd-Pb isotopic data for Early Cretaceous dacites from the Rena-Co area (RCA) in the southern Qiangtang Terrane (QT), central Tibet and use these data to better understand the tectonic evolution of the Bangong–Nujiang suture. LA–ICP-MS dating of zircons yields ages of 109.5 ± 0.6 Ma to 109.6 ± 0.8 Ma for the dacites from the RCA. Geochemically, these dacites are medium-K calc-alkaline and show high SiO2 contents of 64.79–70.37 wt.%, high Sr contents of 517–598 ppm and low Y contents of 8.45–10.7 ppm, similar to those of typical adakites. Additionally, all the rocks are strongly enriched in light rare earth elements and some large ion lithophile elements (e.g. Rb, U, K and Cs) but significantly depleted in high-field-strength elements (e.g. Nb, Ta and Ti), consistent with the geochemical characteristics of arc-type magmas formed in the subduction zone. Moreover, these adakite-like dacites show whole-rock initial (87Sr/86Sr)i ratios of 0.705119 to 0.705491, (206Pb/204Pb)i ratios of 18.489 to 18.508, (207Pb/204Pb)i ratios of 15.591 to 15.612, (208Pb/204Pb)i ratios of 38.599 to 38.686, ϵ Nd (t) values of −0.28 to +1.25 and single-stage Nd model ages of 642 to 818 Ma, as well as significantly positive zircon ϵ Hf(t) values of 3.9–13.1, with young Hf-depleted mantle ages of 331 to 923 Ma. These geochemical and isotopic data indicate that they are most likely derived from the juvenile thickened mafic lower continental crust, which contains partial melts of metasomatized peridotite and subduction-related fluids in the magma source region. Based on previous studies and our new data, we propose that the RCA adakite-like dacites are most likely a result of the northwards subduction of the Bangong–Nujiang Ocean lithosphere beneath the southern QT during the Early Cretaceous and that a slab rollback model could explain the formation of the RCA adakite-like dacites. [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]

Abstract: The Jiama deposit is a large copper deposit in Tibet. Mineralization occurs in three different host rocks: skarn, hornfels and porphyry. A detailed fluid inclusion study was conducted for veins in the different host rocks to investigate the relationship between fluid evolution and ore‐forming processes. Based on examination of cores from 36 drill holes, three types of veins (A, B and D) were identified in the porphyries, four types (I, II, III and IV) in the skarn, and three (a, b and c) in the hornfels. The crosscutting relationships of the veins and that of the host rocks suggest two hydrothermal stages, one early and one late stage. Fluid inclusions indicate that the Jiama hydrothermal fluid system underwent at least two episodes of fluid boiling. The first boiling event occurred during the early hydrothermal stage, as recorded by fluid inclusions hosted in type A veins in the porphyries, type a veins in the hornfels, and wollastonite in the skarns. This fluid boiling event was associated with relatively weak mineralization. The second boiling event occurred in the late hydrothermal stage, as determined from fluid inclusions hosted in type B and D veins in the porphyries, type I to IV veins in the skarns, and type b and c veins in the hornfels. This late boiling event, together with mixing with meteoric water, was responsible for more than 90% of the metal accumulation in the deposit. The first boiling only occurred in the central part of the deposit and the second boiling event took place across an entire interlayered structural zone between hornfels and marble. A spatial zoning of ore‐elements is evident, and appears to be related to different migration pathways and precipitation temperatures of Cu, Mo, Pb, Zn, Au and Ag. [ABSTRACT FROM AUTHOR]