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Located in the eastern section of the Indus‐Yarlung Tsangbo Suture Zone, the Triassic Langjiexue Group is also very important for the distribution of the orogenic gold deposits, such as Bangbu and Zhemulang. Two regional profiles (Jiacha profile and Lang County profile) in the Langjiexue Group have been chosen for systematic mapping. Combing with the method of Ar–Ar dating for mica, this paper provides a detailed analysis of the structural movements and stress periods of the Langjiexue Group, and the relationship between them with the orogenic gold deposits distributed within it, and finally, establish the structural control model for orogenic gold deposits in the Langjiexue Group. The structural deformation of the Langjiexue Group can be divided into 4 stages. In the D1 stage, shallow ductile shear played a dominant role with the principal stress of the reaction in a nearly E–W direction. The main stress of D2 stage was in an obviously S–N direction whose foliation of the axial surface was a ubiquitous phyllitic foliation and foliation. The structures of the D3 stage were superimposed on those of the D2 stage with the main stress of S–N direction. In the D4 stage, the principal stress of the structural movements was in a nearly E–W direction. According to the morphology and spatial positions of the profile folds, the main body of the Songre Formation in the southern parts of the tectonic profiles can be restored into a large reverse antiform, whereas the main body of the Tectonic mélange zone in the northern parts can be restored into a continuous large antiform and synform. Judging by the Ar–Ar plateau ages (56.04 ± 0.72 Ma, 47.98 ± 0.46 Ma) of the sericite in the two quartz veins that were arranged along the axial plane cleavage of the folders in D3 stage, the widely distributed quartz veins in the Langjiexue Group were mainly the outcome of fluid action accompanied by the structural deformation that occurred in the main Indo‐Asian collision orogenesis period, which were in consistent with the mineralogenetic epoch of the orogenic gold deposits in this region. [ABSTRACT FROM AUTHOR]

Abstract: The Zhaxikang Pb‐Zn‐Ag‐Sb deposit, the largest polymetallic deposit known in the Himalayan Orogen of southern Tibet, is characterized by vein‐type mineralization that hosts multiple mineral assemblages and complicated metal associations. The deposit consists of at least six steeply dipping vein‐type orebodies that are hosted by Early Jurassic black carbonaceous slates and are controlled by a Cenozoic N–S‐striking normal fault system. This deposit records multiple stages of mineralization that include an early period (A) of massive coarse‐grained galena–sphalerite deposition and a later period (B) of Sb‐bearing vein‐type mineralization. Period A is only associated with galena–sphalerite mineralization, whereas period B can be subdivided into ferrous rhodochrosite–sphalerite–pyrite, quartz–sulfosalt–sphalerite, calcite–pyrite, quartz–stibnite, and quartz‐only stages of mineralization. The formation of brecciated galena and sphalerite ores during period A implies reworking of pre‐existing Pb–Zn sulfides by Cenozoic tectonic deformation, whereas period B mineralization records extensive open‐space filling during ore formation. Fluid inclusion microthermometric data indicate that both periods A and B were associated with low–medium temperature (187–267°C) and low salinity (4.00–10.18% wt. NaCl equivalent) ore‐forming fluids, although variations in the physical–chemical nature of the period B fluids suggest that this phase of mineralization was characterized by variable water/rock ratios. Microprobe analyses indicate that Fe concentrations in sphalerite decrease from period A to period B, and can be divided into three groups with FeS concentrations of 8.999–9.577, 7.125–9.109, 5.438–1.460 mol.%. The concentrations of Zn, Sb, Pb, and Ag within orebodies in the study area are normally distributed in both lateral and vertical directions, and Pb, Sb, and/or Ag concentrations are positive correlation within the central part of these orebodies, but negatively correlate in the margins. Sulfide S isotope compositions are highly variable (4‰–13‰), varying from 4‰ to 11‰ in period A and 10‰ to 13‰ in period B. The Pb isotope within these samples is highly radiogenic and defines linear trends in 206Pb/204Pb vs. 207Pb/204Pb and 206Pb/204Pb vs. 208Pb/204Pb diagrams, respectively. The S and Pb isotopic characteristics indicate that the period B orebodies formed by mixing of Pb–Zn sulfides and regional Sb‐bearing fluids. These features are indicative of overprinting and remobilization of pre‐existing Pb–Zn sulfides by Sb‐bearing ore‐forming fluids during a post‐collisional period of the Himalayan Orogeny. The presence of similar ore types in the north Rhenish Massif that formed after the Variscan Orogeny suggests that Zhaxikang‐style mineralization may be present in other orogenic belts, suggesting that this deposit may guide Pb–Zn exploration in these areas. [ABSTRACT FROM AUTHOR]

A significant belt of carbonate-hosted Pb–Zn mineralization occurs in the Himalayan–Zagros collisional orogenic system. Three differing types of these Pb–Zn deposits within this belt have been identified based on variations in gangue mineral assemblages, leading to the classification of carbonate-, quartz- and fluorite-rich classes of Pb–Zn deposits. The third Pb–Zn mineralization (fluorite-rich) type is common in this orogenic system, but little research has been undertaken on it. Here, we focus on the Mohailaheng deposit, a large-sized fluorite-rich carbonate-hosted Pb–Zn deposit (> 100 Mt Pb + Zn ores with average grade of 2.18%–4.23%); the deposit is located in the Sanjiang Cenozoic thrust-fold belt, an important part of the Himalayan–Zagros collisional orogenic system and an area that formed during the early Tertiary India–Eurasia collision. The main orebodies in this deposit are stratabound and are hosted by Carboniferous limestones that are located along secondary faults associated with a regional thrust fault. The main assemblage is a sphalerite + galena + pyrite sulfide assemblage associated with a calcite + fluorite + barite + quartz + dolomite gangue assemblage. Detailed field and experimental work indicates that the deposit formed during three distinct phases of hydrothermal activity. Studies on fluid inclusion and stable isotopes of gangue minerals indicate that two dominant distinct fluids involving the deposit formation. They include (1) a low-temperature (130–140 °C), high-salinity (23–24 wt.% NaCl equivalent) basinal brine containing Na + –K + –Mg 2 + –Ca 2 + –Cl − ions and abnormally high SO 4 2 − concentrations, which probably derived from Tertiary basins in the regional district, and (2) a low- to moderate-temperature (170–180 °C) and moderate- to high-salinity (19–20 wt.% NaCl equivalent) metamorphic fluid containing Na + –K + –Mg 2 + –Cl – –SO 4 2 − ions and abnormally high F − and organic matter concentrations, that probably formed during regional metamorphism. Some evaporated seawaters and meteoric fluids were also identified in mixtures with these two dominant fluids. The Pb–Zn mineralization at Mohailaheng formed during three distinct stages, consistent with the regional tectonic history. The first stage involved the formation of favorable lithological and structural traps at Mohailaheng during regional thrusting, leading to the migration of compressed metamorphic waters at depth along a detachment zone, sequestering metals from sediments within the region. Basinal brines at the surface also began to infiltrate down along the secondary faults, dissolving gypsum from the underlying sediments. The second stage was associated with the cessation of thrusting and the onset of strike-slip movements along these thrust faults. Metamorphic fluids containing high concentrations of halogen ions, organic gases, and metals ascended into the structural traps at Mohailaheng along the reactivated thrust faults, causing fluorite, calcite, and some sulfide precipitation. Then, basinal brines rich in SO 4 2 − quickly descended into the structural traps along the reactivated faults, causing reduction of SO 4 2 − by organic matter, and producing significant amounts of H 2 S. The reduced sulfur then reacted with the metals in the fluids, causing significant sulfide precipitation. The third stage was associated with metal-depleted fluids, which only resulted in the precipitation of calcite from the diluted basinal brines. Combining these findings with research results on other fluorite-rich carbonate-hosted Pb–Zn deposits in the Himalayan–Zagros orogenic system suggests that this type of carbonate-hosted Pb–Zn deposits can also be classified as Mississippi Valley-type (MVT) deposits, and that the origin of the fluorite in [ABSTRACT FROM AUTHOR]

Bangpu deposit in Tibet is a large but poorly studied Mo-rich (~ 0.089 wt.%), and Cu-poor (~ 0.32 wt.%) porphyry deposit that formed in a post-collisional tectonic setting. The deposit is located in the Gangdese porphyry copper belt (GPCB), and formed at the same time (~ 15.32 Ma) as other deposits within the belt (12 ~ 18 Ma), although it is located further to the north and has a different ore assemblage (Mo–Pb–Zn–Cu) compared to other porphyry deposits (Cu–Mo) in this belt. Two distinct mineralization events have been identified in the Bangpu deposit which are porphyry Mo–(Cu) and skarn Pb–Zn mineralization. Porphyry Mo–(Cu) mineralization in the deposit is generally associated with a mid-Miocene porphyritic monzogranite rock, whereas skarn Pb–Zn mineralization is hosted by lower Permian limestone–clastic sequences. Coprecipitated pyrite and sphalerite from the Bangpu skarn yield a Rb–Sr isochron age of 13.9 ± 0.9 Ma. In addition, the account of garnet decreases and the account of both calcite and other carbonate minerals increases with distance from the porphyritic monzogranite, suggesting that the two distinct phases of mineralization in this deposit are part of the same metallogenic event. Four main magmatic units are associated with the Bangpu deposit, namely a Paleogene biotite monzogranite, and Miocene porphyritic monzogranite, diabase, and fine-grained diorite units. These units have zircon U–Pb ages of 62.24 ± 0.32, 14.63 ± 0.25, 14.46 ± 0.38, and 13.24 ± 0.04 Ma, respectively. Zircons from porphyritic monzogranite yield ε Hf (t) values of 2.2–8.7, with an average of 5.4, whereas the associated diabase has a similar ε Hf (t) value averaging at 4.7. The geochemistry of the Miocene intrusions at Bangpu suggests that they were derived from different sources. The porphyritic monzogranite has relatively higher heavy rare earth element (HREE) concentrations than do other ore-bearing porphyries in the GPCB and plots closer to the amphibolite lithofacies field in Y–Zr/Sm and Y–Sm/Yb diagrams. The Bangpu diabase contains high contents of MgO (> 7.92 wt.%), FeOt (> 8.03 wt.%) but low K 2 O (< 0.22 wt.%) contents and with little fractionation of the rare earth elements (REEs), yielding shallow slopes on chondrite-normalized variation diagrams. These data indicate that the mineralized porphyritic monzogranite was generated by partial melting of a thickened ancient lower crust with some mantle components, whereas the diabase intrusion was directly derived from melting of upwelling asthenospheric mantle. An ancient lower crustal source for ore-forming porphyritic monzogranite explains why the Bangpu deposit is Mo-rich and Cu-poor rather than the Cu–Mo association in other porphyry deposits in the GPCB because Mo is dominantly from the ancient crust. The Bangpu deposit has alteration zonation, ranging from an inner zone of biotite alteration through silicified and phyllic alteration zones to an outer propylitic alteration zone, similar to typical porphyry deposits. Some distinct differences are also present, for example, K-feldspar alteration at Bangpu is so dispersed that a distinct zone of K-feldspar alteration has not been identified. Hypogene mineralization at Bangpu is characterized by the early-stage precipitation of chalcopyrite during biotite alteration and the late-stage deposition of molybdenite during silicification. Fluid inclusion microthermometry indicates a change in ore-forming fluids from high-temperature (320 °C–550 °C) and high-salinity (17 wt.%–67.2 wt.%) fluids to low-temperature (213 °C–450 °C) and low-salinity (7.3 wt.%–11.6 wt.%) fluids. The deposit has lower δD V-SMOW (− 107.1‰ to − 185.8‰) values compared with other porphyry deposits in the GPCB, suggesting that the Bangpu deposit formed in a shallow [ABSTRACT FROM AUTHOR]

Located on the northeast margin of the Qiangtang terrane between the Jinshajiang suture zone and Bangonghu-Nujiang suture zone, the Dongmozhazhua and Mohailaheng Pb-Zn deposits in the Yushu area of Qinghai Province are representative Pb-Zn deposits of the Pb-Zn-Cu polymetallic mineralization belt in the northern part of the Nujiang-Lancangjiang-Jinshajiang area, which are in the front belt of the Yushu thrust nappe system. The formed environments of these two deposits are different from those of sediment-hosted base metal deposits elsewhere in the world. The authors hold that they were formed during the Indian-Asian continental collision and developed within the fold-thrust belt combined with thrust and strike-slip-related Cenozoic basins in the interior of the collisional zone. Studying on the metallogenic epochs of these two deposits is helpful to the understanding of ore-forming regularity of the regional Pb-Zn-Cu mineralization belt and also to the search for new deposits in this region. The age of the Dongmozhazhua deposit has been determined by the Rb-Sr isochron method for sphalerite residues, whereas the age of the Mohailaheng deposit has been determined by the Rb-Sr isochron method for sphalerite residues and the Sm-Nd isochron method for fluorite. The age of the Dongmozhazhua deposit is 35.0±0.0 Ma ((87Sr/86Sr)0=0.708807) for sphalerite residues. The age of the Mohailaheng deposit is 32.2±0.4 Ma ((87Sr/86Sr)0=0.708514) for sphalerite residues and 31.8±0.3 Ma ((143Nd/144Nd)0=0.512362) for fluorite with an average of 32.0 Ma. Together with the regional geological setting during mineralization, a possible tectonic model for metallogeny of the Dongmozhazhua and Mohailaheng Pb-Zn deposits has been established. These two ages are close to the ages of the Pb-Zn deposits in the Lanping and Tuotuohe basins, indicating that it is possible that the narrow 1000-kilometer-long belt controlled by a thrust nappe system on the eastern and northern margins of the Tibetan plateau could be a giant Pb-Zn mineralized 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 discusses the fluid inclusion and isotopic characteristics of Dongleiwan Skarn Deposit in Jiangxi Province. Topics discussed include tectonic positions of Dongleiwan deposits; main metal mineral ores of deposits such as chalcopyrite, pyrite and bornite; and classification of main mineralization stage into four categories.

The northeastern Gangdese polymetallic belt is one of the most important metallogenic belts in the Tibetan collisional orogen. In this belt, three types of mineralization including skarn type Fe, skarn and breccia type Pb–Zn–Ag, porphyry and skarn type Mo–Cu–W have been recognized. Some deposits are polymetallic deposits with complex metal paragenetic assemblage which needs to be explained. The Lietinggang–Leqingla skarn deposit is the most typical one which have developed Pb–Zn–Fe–Cu–Mo five kinds of metals in the same deposit. Geological field mapping indicates that the ore district is characterized by a regular spatial zoned alteration and mineralization. Garnet skarns with Fe–Cu–Mo mineralization are developed near the intrusion, while the garnet–hedenbergite skarns and the more distal hedenbergite–ferroactinolite skarns with Pb–Zn–Cu mineralization are developed in the carbonate strata. According to the dating date, the Fe–Cu–Mo and Pb–Zn–Cu mineralization formed in the same metallogenic system. Mineralogical studies suggest that from the prograde skarn alteration stage, during the retrograde alteration stage to the oxide stage, and to the quartz–sulfide stage, the fluid conditions for skarns near the intrusion were moderately acidic and weakly oxidizing, relatively oxygenated and alkaline, and weakly oxidizing and alkaline, respectively. However, for the skarns in the carbonate strata, they were lower acidities and weakly reducing, relatively low acidities and reducing, and reducing with a low pH, respectively. Geochemical analyses give information about the elements for the skarnization and mineralization. About the element sources, the host carbonate rocks were mainly responsible for Ca and the magmatic fluids were responsible for Si, Fe and Mg. About the element migration, during the hydrothermal alteration the grossularite skarns and garnet–epidote skarns gained Fe, Mg, Mn, Ca and Sr, but lost Si and K; the andradite skarns, garnet–hedenbergite skarns and hedenbergite–ferroactinolite skarns gained Si, Fe, Mn and Mg, but lost in Ca, K and Sr; and all the skarns gained Co, V, Y, Pb, Zn and Cu, but lost Rb and Ba. The REE migrated mainly in magmatic fluids and enriched in the skarns during the prograde skarn alteration stage. However, they reacted by the ore-forming fluids and migrated out of the system, which process led to the decreasing of these elements in skarns at last. By summarizing studies here and previously published data, a genetic description for the Lietinggang–Leqingla Pb–Zn–Fe–Cu–Mo skarn deposit can be given as follows. The Fe–Cu–Mo mineralization within the garnet-rich zone formed by the interaction between fluids derived from the Jubuzhari composite intrusion and the neighboring carbonate units under a condition of oxidizing and higher temperature. The Pb–Zn–Cu mineralization within the hedenbergite and ferroactinolite-rich zone formed by the interaction between fluids also derived from the Jubuzhari composite intrusion but migrated relative long distance and distal carbonate units under a condition of reducing and lower temperature. [ABSTRACT FROM AUTHOR]

Fault zones control the locations of many ore deposits, but the ore-forming processes in such fault zones are poorly understood. We have studied the deformation and ore textures associated with fault zones that controlled the lead–zinc mineralization of the Dongmozhazhua deposit, central Tibet, ∼100 km southwest of Yushu City. Geological mapping shows that the structural framework of the Dongmozhazhua area is defined by NW–SE-trending reverse faults and superposed folds that indicate at least two stages of deformation. The first stage is characterized by tight nearly E–W-striking folds that formed during the closure of the Jinshajiang Paleo-Tethyan Ocean in the Triassic. The second stage of deformation produced NW–SE-trending reverse faults and related structures of the Fenghuoshan–Nangqian fold-and-thrust belt associated with India–Asia collision in the late Eocene to Oligocene. Scanline surveys along the ore-controlling fault zones show an internal structure that comprises a damage zone, a breccia zone with clasts that have become rounded, and a breccia zone with lenticular clasts, and this complex architecture was formed during at least two compressional substages of deformation. The Pb–Zn mineralization in the Dongmozhazhua area occurs exclusively close to NW–SE-trending reverse fault zones. Microtextural observations reveal that mineralization occurred as veinlets and disseminated blebs in limestone clasts, and as continuous bands and cements in fractured rocks. Cataclastic sulfide grains also can be seen in the matrix of some fault zones. The types of mineralization differ with structural position. The fillings of the ore-bearing veinlets typify the products of hydraulic fracture and both types of mineralization took place concurrently with regional contraction. We consider, therefore, that the ore-bearing fluids in the Dongmozhazhua deposit were concentrated in fault zones during regional compression and that the ore minerals were precipitated during hydraulic fracturing of host rocks. Subsequent fault activity pulverized some pre-existing sulfide material into cataclastic grains in the matrix of a tectonic breccia that developed in the same faults. [ABSTRACT FROM AUTHOR]

Mengya’a is a typical Pb–Zn–(Ag) deposit in the Lhasa terrane, which is located in the eastern part of the central Lhasa subterrane, Tibet. Two different types of Pb–Zn–(Ag) mineralization (skarn and porphyry-like styles) have been identified in the Mengya’a mining district. The skarn-type mineralization occurs as layered or lenticular units in the Laigu Formation and contains nearly all the Pb–Zn ore resources, whereas the porphyry-like mineralization exists mainly as veins in granite porphyry. 40 Ar/ 39 Ar dating of muscovite suggests that the skarn orebodies formed at 54.8 ± 0.4 Ma, whereas zircon U–Pb dating of granite porphyry (13.2 ± 0.2 Ma) indicates that the porphyry-like mineralization formed in the Miocene. As such, the primary mineralization event (skarn type) took place during the main Indo-Asia collision. The ore-forming mineralization and alteration characteristics of the Mengya’a deposit are consistent with other examples of regional Pb–Zn–(Ag) mineralization in the Lhasa terrane. The present results, combined with previous studies, indicate that multiple Pb–Zn–(Ag) mineralization events occurred in the Lhasa terrane, including during the Cretaceous, Paleocene, and Miocene, all of which were associated with felsic intrusions. Sulfur and lead isotopes suggest that the Pb–Zn–(Ag) mineralization events were mainly magmatic in origin, and were closely associated with the ancient basement of the central Lhasa subterrane. Whole rock major and trace elements, and zircon Hf isotope data of the ore-forming intrusions indicate that these intrusions are S-type granites, produced mainly by partial melting of the ancient crust, which underwent extensive fractionation. Therefore, the presence of moderately to strongly fractionated S-types granites, along with the ancient crustal magma source, were the key factors in generating the Pb–Zn–(Ag) mineralization in the central Lhasa subterrane. Crustal melting in the central Lhasa subterrane peaked in the Paleocene, and resulted in the most intense Pb–Zn–(Ag) mineralization during the initial stages of Indo-Asia continental collision (65–50 Ma). During the Cretaceous, the scale of crust melting was considerable, creating large Pb–Zn–(Ag) deposits. Limited Miocene crustal melting and magmatism in the central Lhasa subterrane resulted in the Miocene Pb–Zn–(Ag) mineralization being smaller in scale than that in the Paleocene and Cretaceous. [ABSTRACT FROM AUTHOR]