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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]

The Longmala deposit is a representative of the skarn Pb-Zn-Cu deposits found in the Nyainqêntanglha area of Tibet, China. The mineralization is hosted by skarn and marble of the Permian Wululong Formation intruded by an early Eocene biotite monzogranite, which is associated with the Pb-Zn-Cu mineralization. The genesis of the deposit is related to a four-stage progression involving: Stage I involves the development of prograde skarn; Stage II is a pre-ore retrograde skarn; Stage III is the emplacement of quartz-sulfides ore; and Stage IV is the emplacement of post-ore carbonate. The biotite monzogranite is a high-K calc-alkaline highly fractionated I-type granite characterized by its elevated SiO 2 (68.38–72.62 wt%), Fe T (4.09–6.19 wt%), and K 2 O + Na 2 O (7.82–8.33 wt%) contents. Its aluminum saturation index of 0.97–0.99 and a high differentiation index of 79–86 are indicative of a last-stage fractionation of the magma. The monzogranite is relatively enriched in light rare-earth elements, Th, U, and Rb, depleted in Sr, Ba, K, Nb, P, and Ti, and has a negative Eu anomaly. The εHf (t) values (−6.2 to +1.5), two-stage Hf model ages (average T DM2 = 1224 Ma) for zircons, and whole rock Pb isotopic compositions ( 206 Pb/ 204 Pb = 18.806–18.938, 207 Pb/ 204 Pb = 15.676–15.697, and 208 Pb/ 204 Pb = 39.234–39.376) indicate that the source of the magma is the crust of Lhasa Terrane. The study of fluid inclusions from each of the four stages mentioned above show that garnet and diopside from the prograde skarn (Stage I) are characterized by high temperatures and high oxygen fugacity indicative of magmatic fluids. The succeeding mineralization (Stage III) is characterized by moderate to high temperature and a reducing fluid, and final carbonate veining (Stage IV) with a decreased fluid temperature and salinity. The δ 18 O w values range from 1.3 to 10.8‰, and the δD w values are −123.5 to −93.4‰, indicating that the ore-forming fluids were derived from mixture magmatic and meteoric fluids, and the δ 34 S values of sulfides have a relatively narrow range of 0.3–3.6‰, suggestive of a magmatic source. The 206 Pb/ 204 Pb (18.571–18.722), 207 Pb/ 204 Pb (15.707–15.796), and 208 Pb/ 204 Pb (39.116–39.448) values of sulfides show that ore-forming metals were derived from the crust in the Lhasa Terrane. Major and trace elements characteristics of the ore-associated biotite monzogranite, combined with the dating results, suggest that the Longmala deposit were formed within the India-Asia continental-collision tectonic setting. [ABSTRACT FROM AUTHOR]

Stable Zn isotopes may be applied to trace the source of ore-forming metals in various types of Pb Zn deposits. To test this application, Zn and Pb isotope systematics for sulfides and associated basement rocks as well as Fe Mn carbonates (gangue) from the Zhaxikang Pb Zn deposit in South Tibet have been analyzed. The basement in this region includes metamorphosed mafic to felsic rocks (dolerite, quartz diorite, rhyolite porphyry, pyroclastics and porphyritic monzogranite). These rocks have similar δ 66 Zn values of 0.33 to 0.37‰, with an average value of 0.36 ± 0.03‰ (2σ), except for the more evolved porphyritic monzogranite that has a heavier value of 0.49‰. Fe Mn carbonates are present as hydrothermal veins and were probably precipitated from magmatic fluids. They have an average δ 66 Zn value of 0.27 ± 0.05‰, which is slightly lighter than the basement rocks, possibly representing δ 66 Zn isotopic compositions of the hydrothermal fluids. Sphalerite and galena have similar Zn isotopic compositions with δ 66 Zn ranging from 0.03 to 0.26‰ and 0.21 to 0.28‰, respectively. Considering the Zn isotope fractionation factor between sphalerite and fluids of − 0.2‰ at ~ 300 °C as reported in literature, hydrothermal fluids from which these sulfides precipitated will have δ 66 Zn values of ca. 0.39 ± 0.10‰, which are consistent with the values of basement rocks and the Fe Mn carbonates. This similarity supports a magmatic-hydrothermal origin of the Zhaxikang Pb Zn deposit. Both Pb and S isotopes in these sphalerite and galena show large variations and are consistent with being derived from a mixture of basement and sedimentary rocks in various proportions. Zn isotopic compositions of the sulfides significantly extend the range of regional basement rocks, suggesting that sedimentary rocks (e.g., shales) are also a significant source of Zn. However, the Zn isotopic compositions of sphalerite and galena differ from those of marine carbonates and those of typical SEDEX-type deposits (e.g. Kelley et al., 2009), confirming a magmatic-hydrothermal model. Combined with regional geological observations and the age constraints of ~ 20 Ma (Zheng et al., 2012, 2014), the results of our investigation indicate that the Zhaxikang Pb Zn deposit is most likely a magmatic-hydrothermal 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 Jiama copper deposit is one of the largest deposits recently found in Tibet and is composed of three types of mineralization including skarn, hornfels and porphyry. To investigate the relationship between mineralization, structure and alteration, we report new zircon U-Pb age and present field observations on the deformation characteritics associated with the copper mineralization in Jiama. Two main periods of deformation were identified, represented by D1 and D2 in Jiama. The first deformation ( D1) occurred around 50 Ma, whereas the second deformation ( D2) that was closely related to mineralization occurred later. Previous zircon U-Pb and molybnite Re-Os dating results indicate that the mineralizatoin occurred at ∼15 Ma and thus the D1 regional deformation significantly occurred before the mineralization time, although the D1 deformation probably provided important space for the development of significant copper deposition. Our new mapping and observations on the D2 deformation demonstrate that the mineralization was closely coeval with or slightly later than the time of D2 deformation. The new U-Pb zircon age further indicates that the aplite formed in ∼17.0 Ma and thus the D2 deformation happened later than this time because the D2 deformation cut across the aplite, which is proposed to be the key control for copper mineralization. Altered laminated hornfels including three types of alteration ( A-, K- and S-type) were found spatially associated with the D2 deformation. The type- A is mainly silicification, with fine sericite or chlorite, as well as abundant disseminated sulphides on fracture surfaces; the type- S is mainly fine-grained silicification with patches of chlorite, epidote and common sulphides; the type- K (potassic alteration) appears to be fine-grained biotite. Such types of alteration indicate the presence of skarns at depth where ore shoots are located. Taken together, the multiple structural-magmatic-mineralization events contributed to the formation of the supergiant Jiama porphyry copper deposit in Tibet. The results have general implication for regional exploration. [ABSTRACT FROM AUTHOR]

The article discusses a study that focuses on the minerals, geological alteration and fluid basics of the first high sulfidation epithermal-porphyry copper-gold deposits in Tibet, China. Topics discussed include discovery of some new copper-sulfur and copper-iron-sulfur minerals; role of temperature and salinity in fluid inclusions and mixing of meteoricwater and porphyry fluid to form deposits in low temperature and salinity.

The article discusses the petrogeochemistral features of the acid intrusive rocks in Zhaxikang Deposit, Xizang Region. Topics discussed include geochemical analysis of granite porphyry samples that revealed high alumina, high silica and low magnesium oxide; rare earth element geochemistry of granite porphyry samples; and positive Europium (Eu) anomalies in which concentration of Eu increases in the mineral.

The article offers information on the geochemical features and prospecting development of Southern Tiegelong Giant Epithermal Copper Deposit in Tibet, China. Topics discussed include types of metallic sulphides ores detected by energy spectroscopy scanning; metallogenic stages of mineralization such as sedimentary diagenesis and hydrothermal mineralization; and formation of deposits in Early Cretaceous era.

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 research study conducted that examines the genetic types of mineral deposits of Xiongcun District in Gangdese porphyry copper belt in Tibet, People's Republic of China (PRC). It mentions the genesis of the Gangdese deposit as epithermal, porphyry, and porphyry-epithermal deposit. It further mentions that the deposit is characterized by developed pyrrhotite and ilmenite, that have similar mineral assemblages to the reduced porphyry copper-gold deposit (RPCDs).

The Tiegelongnan is the first discovered porphyry–epithermal Cu (Au) deposit of the Duolong ore district in Tibet, China. In order to constrain the thermal history of this economically valuable deposit and the rocks that host it, eight samples were collected to perform a low‐temperature thermochronology analysis including apatite fission track, apatite, and zircon (U‐Th)/He. Apatite fission track ages of all samples are between 34 ± 3 and 67 ± 5 Ma. Mean apatite (U‐Th)/He ages show wide distribution, ranging from 29.3 ± 2.5 to 56.4 ± 9.1 Ma. Mean zircon (U‐Th)/He ages range from 79.5 ± 12.0 to 97.9 ± 4.4 Ma. The exhumation rate of the Tiegelongnan deposit was 0.086 km m.y.−1 between 98 and 47 Ma and decreased to 0.039 km m.y.−1 since 47 Ma. The mineralized intrusion was emplaced at a depth of about 1400 m in the Tiegelongnan deposit. Six cooling stages were determined through HeFTy software according to low‐temperature thermochronology and geochronology data: (i) fast cooling stage between 120 and 117 Ma, (ii) fast cooling stage between 117 and 100 Ma, (iii) slow cooling stage between100 and 80 Ma, (iv) fast cooling stage between 80 and 45 Ma, (v) slow cooling stage between 45 and 30 Ma, and (vi) slow cooling stage (<30 Ma). Cooling stages between 120 and 100 Ma are mainly caused by magmatic–hydrothermal evolution, whereas cooling stages after 100 Ma are mainly caused by low‐temperature thermal–tectonic evolution. The Bangong–Nujiang Ocean subduction led to the formation of the Tiegelongnan ore deposit, which was buried by the Meiriqiecuo Formation andesite lava and thrust nappe structure; then, the Tiegelongnan deposit experienced uplift and exhumation caused by the India–Asia collision. [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 article presents a study to determine geological importance of rhenium (Re)-osmium (Os) isotopic dating of molybdenites in the Galale skarn copper (Cu)-gold (Au) deposit in Tibet, China. Topics discussed include determination of the age of granodiorite by using the laser ablation-inductively coupled plasma-mass spectrometry, isochron ages of Re-Os testing, and galale deposit and gaerqiong deposit resulting from magma-mineralization.

Copper resources in China are rich, but imported copper products are still required. Researches on metallogenic regularity of major types of copper deposits by geologists have involved in worldwide classification, significant copper belts, representative copper deposits, etc. Studies on metallogenic regularity of copper deposits in China also have made achievements with a long-term work. Combined with latest exploration advances obtained in recent ten years, this review aims to conclude the achievements of researches on copper metallogenic regularity in China. Based on data of 814 copper deposits and other ore (mineralized) occurrences, ten prediction types of copper deposits have been suggested. Porphyry and skarn copper ores are taken as the key targets. Porphyry copper deposits are the most important one which concentrate in Gangdese, Changdu-Sanjiang, Dexing and East Tianshan. The Cenozoic and Mesozoic are the major metallogenic epochs. Four main metallogenic epochs are been studied based on the copper ore geochronological data including Precambrian Era (Archean and Proterozoic), Paleozoic Era, Mesozoic Era and Cenozoic Era. Based on the study of metallogenic series of ore deposits in China, twenty-seven metallogenic series of copper deposits are proposed. This is suggested to deepen the study of metallogenic regularity of copper ore and provide the theory guide for copper resources prediction in China. [ABSTRACT FROM AUTHOR]