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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]

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]

The Xin'gaguo deposit is representative of the skarn Pb–Zn polymetallic zone in the northern Gangdese porphyry metallogenic belt, Tibet. Pb–Zn mineralization is hosted in the Take'na formation skarn. The Xin'gaguo ore‐forming process can be divided into prograde skarn, retrograde skarn and quartz‐sulfides. Skarn minerals include garnet, diopside, and epidote, with minor wollastonite, actinolite, and chlorite. Metallic minerals are mainly sphalerite, galena, chalcopyrite, magnetite, and pyrrhotite, with minor arsenopyrite, marcasite, native bismuth, cosalite, and gersdorffite. The LA–ICP–MS zircon U–Pb age of the diorite is 59.66±0.52 Ma. Diorite samples are characterized by fractioned REE patterns with marked positive Eu anomalies, enriched LILEs (Rb, Ba, Th, U, and K) and depleted HFSEs (Ta, Nb, Zr, Hf, and Ti), belong to the calc‐alkaline series and have metaluminous compositions. Zircon εHf(t) values of the diorite are positive (5.7–11) and lie between the chondrite and mantle values. These geochemical characteristics suggest that the diorite was formed by the partial melting of a young metasomatized asthenospheric mantle wedge deriving basaltic rocks. The δ34S values of sulfides range from −4.7 to 4.5‰ and show a bimodal distribution, indicating interactions of magma‐derived ore fluid with biogenic sulfide minerals from the Take'na formation. The 206Pb/204Pb (18.5–18.629), 207Pb/204Pb (15.599–15.704), and 208Pb/204Pb (38.616–38.975) of sulfides show that ore‐forming metals were derived from mixed sources, in part from the Lhasa Terrane basement. Skarn mineral compositions imply that the ore‐forming environment was variable, and underwent at least three changes in oxidation‐reduction state. The geochemical characteristics of diorite indicate that the Xin'gaguo deposit formed within the Indo‐Asian continental collision tectonic setting. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • First reported of 84–95 Ma high Mg# adakites in the west central Lhasa subterrane. • New geodynamic setting for the 80–95 Ma porphyry-skarn Cu-Mo-Au deposits in the BNMT. • Modified juvenile crust components played key roles in the Cu-Mo-Au mineralization. Abstract The Ga'erqiong-Galale ore district in the Bangong-Nujiang metallogenic belt hosts two large skarn Cu-Au deposits, associated with voluminous Late Cretaceous volcanism and plutonism. In this study, we present new zircon U-Pb age and Hf isotopic data, whole-rock geochemical and Sr-Nd-Pb isotopic data to constrain the geodynamic mechanisms of Late Cretaceous magmatism and metallogenesis within the Ga'erqiong-Galale ore district. The intrusive rocks in the district include diorite, quartz diorite, granodiorite, granite, and dioritic porphyrite. Zircon U-Pb analyses suggest those rocks mainly emplaced at early Late Cretaceous (84–95 Ma), which coincide with the ore-forming age of Ga'erqiong and Galale deposits (87 and 88 Ma, respectively). Geochemically, the granodiorite and dioritic porphyrite are metaluminous with depletion of Nb, Ta, and Ti and characterized by high MgO (2.68–4.16 wt%), Mg# (55–87), Sr (414–616 ppm), Sr/Y (30–56), Cr (22.5–105.0 ppm), and Ni (26.6–59.7 ppm), low Y (10.6–14.0 ppm), and heavy rare earth elements (HREE), showing geochemical signatures of high Mg# adakitic rocks. Four dioritic porphyrite and three granodiorite samples exhibit homologous Sr-Nd-Pb isotope compositions and have positive whole rock ε Nd (t) values of +1.1 to +3.0, (87Sr/86Sr) i values of 0.7045–0.7048, (206Pb/204Pb) t ratios of 18.42–18.73, (207Pb/204Pb) t ratios of 15.58–15.63, and (208Pb/204Pb) t ratios of 38.54–38.88. Besides, 116 analyses from the Ga'erqiong-Galale adakitic rocks give positive zircon ε Hf (t) values (+4.3 to +12.1). The geochemical and isotopic data indicate that the early Late Cretaceous high Mg# adakitic rocks in the Ga'erqiong-Galale ore district originated from the delaminated juvenile lower mafic crust that has been modified by the previously subduction. Partial melting of previously subduction modified, delaminated juvenile lower crust not only formed the hydrous adakitic melts in highly oxidation state, but also provided the ore metals (e.g., Cu, Au, Mo) for the subsequent mineralization. Such melts reacted with surrounding mantle peridotite to elevate the contents of metallic elements again. Then the melts experienced varying degrees of fractional crystallization process in the shallow magma chamber to form the dioritic and granodioritic magmas. Those magmas emplaced into the limestone of Duo'ai and Jiega Formation to form the Ga'erqiong and Galale skarn Cu-Au deposits, respectively. Field observation, together with geochronological and geochemical data, indicate that the early Late Cretaceous mineralization events in the northern and central Lhasa subterranes took place in a transition tectonic setting from collisional orogeny to extension and the input of subduction modified juvenile crust play an important role in the Late Cretaceous ore-forming events. [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]

This article reports new zircon laser ablation-multicollector-inductively coupled plasma-mass spectrometry U-Pb and Hf isotope, whole-rock major and trace element, and Sr-Nd isotope data for mineralized and barren intrusions associated with the Duolong porphyry-epithermal copper-(gold) deposit (DPCD, a mining camp containing several individual deposits) in the western Qiangtang Terrane (QT), central Tibet. These data are used to further our understanding of the geological evolution of this region. The mineralized and barren DPCD intrusions are typical I-type granitoids that were synchronously emplaced at ca. 112.6-125.9 Ma. These igneous rocks show arc affinities that are characterized by enrichments in the light rare earth elements (LaN/YbN = 4.08-15.23) and the light ion lithophile elements (Rb, Th, U, K, and Pb), and depletions in the high field strength elements (Nb, Ta, and Ti). They have 87Sr/86Sr(i) values of 0.7046-0.7079, Nd(t) values of -6.0 to +1.1, and two-stage Nd model ages of ca. 823-1410 Ma. Zircons from these intrusive rocks have variable but generally positive εHf(t) values (-2.7 to +13.7) and relatively young zircon Hf crustal model ages of 335-1351 Ma. Combining these data with geochemical data reported in recent studies, we infer that the mineralized and barren DPCD intrusions formed in a continental marginal arc setting and likely originated from a common parental magma that was result of magma mixing of juvenile crust-derived basaltic melts and old lower crust-derived melts. The formation of the DPCD intrusions indicates that the Bangongco-Nujiang oceanic lithosphere was still undergoing northward subduction beneath the western QT at ca. 112.6-125.9 Ma, suggesting in turn that the oceanic basin have not closed completely during the Early Cretaceous. These new data also indicate that the processes that occur during the subduction of oceanic crust in continental marginal arc settings produce and preserve juvenile crustal material, leading to net continental crust vertical growth and thickening. [ABSTRACT FROM AUTHOR]

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 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]

The Leqingla and Xin'gaguo deposits are two representative skarn Pb–Zn polymetallic deposits of the Gangdese Pb–Zn polymetallic belt, Tibet, China. LA-ICP-MS zircon U–Pb dating of the mineralization-related biotite granites from both the Leqingla and Xin'gaguo deposits yielded weighted mean ages of 60.8 Ma and 56.5 Ma, respectively, which can be inferred as their mineralization ages. The Leqingla biotite granite is characterized by high Al 2 O 3 , total Fe, Na 2 O, and low K 2 O. In comparison, the Xin'gaguo biotite granite is characterized by relative higher K 2 O but lower Al 2 O 3 , total Fe, and Na 2 O. Geochemical and mineralogical characteristics indicate that the Leqingla and Xin'gaguo biotite granites are calc-alkaline I-type granite and High K calc-alkaline I-type granite, respectively. Both the Leqingla and Xin'gaguo biotite granites are enrichment in LREE and LILEs and depletion in HFSEs, and they were formed at the India–Asia collision stage. δ 18 O and δD values for the Leqingla and Xin'gaguo deposits are −8.8‰ to 5.3‰ and −140.4‰ to −90.1‰, −4.5‰ to 7.0‰ and −117.3‰ to −81.0‰, respectively, indicating magma fluids mixed with meteoric water in ore-forming fluids. δ 34 S values (−11.6‰ to −0.3‰) of ore sulfides from the Leqingla deposit show characteristics of biogenetic sulfur isotope compositions, suggesting sulfur for the Leqingla deposit were sourced from wall rocks of the Mengla and Luobadui Formation, which are rich in organic materials. δ 34 S values of ore sulfides from the Xin'gaguo deposits show bimodal distribution (−5.0‰ to −1.6‰ and 1.6–2.1‰), indicating sulfur in the Xin'gaguo deposit were derived from both wall rocks and magma. In the Leqingla deposit, most ore sulfides have the similar Pb isotopic compositions with that of the mineralization-related biotite granite, suggesting the biotite granite supplied most of the ore-forming metals. Pb isotopic compositions of ore sulfides and Hf isotopic compositions of biotite granite show that the majority of ore-forming metals are derived from mantle components of partial melting of the Neo-Tethys Ocean slab, with some upper crust materials of the Lhasa terrane. Pb isotopic compositions of ore sulfides from the Xin'gaguo deposit are similar to that of the Leqingla deposit, indicating they have the similar sources of ore-forming metals. [ABSTRACT FROM AUTHOR]