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The southern margin of the North China Craton (SNCC) contains 8 giant (> 0.5 Mt Mo resources), 4 large (0.1–0.5 Mt Mo resources) and many small (< 0.1 Mt Mo resources) porphyry Mo deposits. Their magmatism ages are concentrated within 150–131 Ma, but it is unclear what determines the size of porphyry Mo systems. Herein, we synthesize new and existing data for the Mo-bearing intrusions in the SNCC to investigate the optimal conditions for giant deposit formation. These intrusions share similar whole-rock geochemistry characteristics and highly differentiated features, with SiO2 and K2O contents ranging from 68.55 to 79.13 wt.% and 2.63 to 11.18 wt.%, respectively. They share similar lower crustal sources with a variable input of mantle materials. Their εNd(t) and εHf(t) values range from -19.1 to -12.7 and -29.5 to -9.3, respectively, and indicate no relationship with metal fertility. The similar ΔFMQ values calculated from zircon geochemistry also suggest that the porphyry Mo deposit size is unrelated to magma redox conditions. High magmatic water contents and high differentiation features (SiO2 > 73 wt.%) exhibit significant positive correlations with the deposit size. Therefore, we propose that magma with a high water content triggered by intensive fractional crystallization is the fundamental requirement to produce large Mo endowment in the SNCC. This conclusion is consistent with the criteria that pulsed release of mineralizing fluids from a large magma chamber through fractional crystallization play an important role in the formation of giant porphyry Mo deposits in other molybdenum belts in the world. [ABSTRACT FROM AUTHOR]

This study, via combined analysis of geophysical and geochemical data, reveals a lithospheric architecture characterized by crust–mantle decoupling and vertical heat-flow conduits that control orogenic gold mineralization in the Ailaoshan gold belt on the southeastern margin of Tibet. The mantle seismic tomography indicates that the crust–mantle decoupled deformation, defined from previous seismic anisotropy analysis, was formed by upwelling and lateral flow of the asthenosphere, driven by deep subduction of the Indian continent. Our magnetotelluric and seismic images show both a vertical conductor across the Moho and high Vp/Vs anomalies both in the uppermost mantle and lowest crust, suggesting that crust–mantle decoupling promotes ponding of mantle-derived basic melts at the base of the crust via a heat-flow conduit. Noble gas isotope and halogen ratios of gold-related ore minerals indicate a mantle source of ore fluid. A rapid decrease in Cl/F ratios of lamprophyres under conditions of 1.2 GPa and 1050°C suggests that the ore fluid was derived from degassing of the basic melts. Similar lithospheric architecture is recognized in other orogenic gold provinces, implying analogous formational controls. [ABSTRACT FROM AUTHOR]

The Beiya porphyry‐skarn Au deposit is one of the largest gold deposits in China, temporally and spatially associated with Eocene intrusions in a post‐collisional setting in western Yunnan, China. In this study, we report new whole‐rock geochemistry, Sr‐Nd isotope, zircon U‐Pb geochronology and in situ zircon Hf‐O isotopes of quartz‐monzonite and biotite‐monzonite porphyries from the Beiya deposit. The porphyry‐skarn mineralization at the Beiya deposit is mainly associated with the quartz monzonite porphyry (35.8 ± 0.6 Ma), while the biotite‐monzonite porphyry (34.3 ± 0.5 Ma) represents a post‐mineralization intrusion crosscutting the main orebodies and the quartz‐monzonite porphyry. Both intrusions have high‐K and adakitic composition and are characterized by high Sr/Y ratios, high SiO2 and Al2O3 concentrations (SiO2 = 69.80–73.86 wt%; Al2O3 = 14.11–15.19 wt%), and low MgO, Cr, and Ni concentrations (MgO = 0.2–1.0 wt%; Cr = 1.76–11.13 ppm; Ni = 2.52–11.72 ppm). Their Sr‐Nd isotope compositions (87Sr/86Sr = 0.7066–0.7077; εNd(t) = –5.3 to –1.5) are consistent with the lower crustal‐derived amphibolite xenoliths (87Sr/86Sr = 0.7060–0.7100; εNd(t) = –10.0 to 0.0), indicating that they might be derived from a thickened juvenile lower crust beneath the Yangtze Craton. The biotite‐monzonite porphyry has lower zircon δ18O values of +5.3‰ to +6.8‰ and higher εHf(t) values of –2.3 to +5.5 than those of the quartz‐monzonite porphyry with δ18O values of +7.1‰ to +8.2‰ and εHf(t) values of –3.8 to +1.5, implying that they were derived from different parts of the lower crust. High Ba/La and Pb/Ce ratios suggest that the quartz‐monzonite porphyry is derived from a volatiles‐rich reservoir. Relatively higher La/Yb, Sm/Yb and Dy/Yb ratios of the biotite‐monzonite porphyry indicate residual garnet in the source, indicating a deeper source than that of the quartz‐monzonite porphyry. The hydrous components should be represented by the amphibole‐rich lithologies, which has relatively shallower depth than that of the garnet‐bearing mafic thickened lower crust. Our data suggest that the mineralized quartz‐monzonite porphyry at the Beiya deposit is derived from partial melting of amphibole‐rich lithologies in the upper part of the thickened juvenile lower crust beneath the Yangtze Craton, while the post‐mineralization biotite‐monzonite porphyry is derived from the basal, and volatiles‐poor, part of the juvenile lower crust. [ABSTRACT FROM AUTHOR]

The Tethyan metallogenic domain (TMD), as one of the three major domains in the world, extends over 10000 km from east to west, and has developed several world-class metallogenic belts, such as the Gangdese porphyry Cu belt, the Sanjiang metallogenic belt, the Iran porphyry Cu belt, the Pakistan porphyry Cu belt, the southeastern European epithermal gold deposit belt, and the Southeast Asian Sn belt. The formation and evolution of the TMD is mainly controlled by the multi-stage subduction of Tethys oceanic slabs, the opening and closing of several small ocean basins, and continent-continent collision. The Tethys oceans include the Proto-Tethys (Cambrian-Silurian), Paleo-Tethys (Carbonaceous-Triassic) and Neo-Tethys (Jurassic to Cretaceous), which in turn are formed by rifting from the Gondwana land at different times in different micro-continents. With a series of geological processes such as oceanic opening and closing, continental collision and post-collisional reworking with intraplate deformation, various types of ore deposits are developed in the TMD, including porphyry deposits, epithermal deposits, VMS deposits, chromite deposits, Sn deposits and orogenic gold deposits. The metallogenic processes of the TMD can be categorized into three stages. (1) Oceanic subduction: With the subduction of the oceanic slab and dehydration of basalt and sediments, the asthenospheric mantle was metasomatized with preliminary enrichment in metals under oxidized condition. (2) Continental subduction: Continental collision induced partial melting of the mantle wedge enriched the metals and water in mafic melts, which ascended from subarc depths to the lower crust, locally to the shallow crust for hydrothermal mineralization. (3) Post-collisional reworking: Partial melting of the mafic intrusives in the lower crust produced felsic melts under oxidized and water-rich conditions, which underwent crystal fractionation and transferred water and metals into hydrothermal fluids for mineralization. The large-scale porphyry mineralization in the TMD mainly occurs in the Miocene, which is an important scientific issue worthy of further study in the future. How is the metal enriched in the processes of gradual maturity of the crust, and how does large-scale mineralization occur in a collisional orogen where there is no subduction and dehydration of oceanic slabs anymore to supply S and Cl? These are still important questions in the study of porphyry mineralization in the Tethyan orogen. The application of hyperspectral and mineralogical studies of alteration assemblages is beneficial for prospecting and exploration in the TMD. [ABSTRACT FROM AUTHOR]

Saindak is one of the typical porphyry Cu deposits (PCDs) in the Chagai magmatic arc in Pakistan. Ore-forming porphyries at Saindak PCD are mainly composed of tonalite. Here, we use geochemistry of apatite enclosed in plagioclase phenocrysts from the ore-forming tonalite to constrain the releasing and recharging processes of S and Cl in the underlying parental magma chamber during PCD mineralization. Although apatite inclusions have homogeneous intra-grain S and Cl compositions, there is significant inter-grain S and Cl variations in apatite inclusions located from core to rim in the hosting plagioclase. Such inter-grain S and Cl variation in apatites are coupled with the core-to-rim trends of An, FeO and Mg contents of the hosting plagioclase phenocryst. It indicates that the Saindak PCD likely formed by episodic injection of primitive magmas during the growth of an underlying magma chamber, rather than by one major injection or by addition of mafic melt derived from different source region. Each primitive melt injection introduced essential ore-forming materials such as S and Cl, which were rapidly and effectively released to the coexisting fluids, causing mineralization. Once primitive melt injection stops, signaling the end of growth of underlying magma chamber, mineralization will cease quickly although the hydrothermal system can still survive for a long time. However, the later released fluids are relatively depleted in ore-forming materials, and thus have lower capability to generate mineralization. Accordingly, predominant porphyry-type mineralizations occurred during the growth rather than waning stage of a magmatic system. [ABSTRACT FROM AUTHOR]

Modern collisional orogens represent the natural laboratory for the study of metallogeny in continental collision zones. The Pyrenees, Alps, Zagros and Himalaya are all associated with Neo-Tethyan subduction and represent the youngest collisional orogens on Earth. Here, we compare these four orogens in terms of their composition, architecture, tectonic evolution, and metallogenic systems. The four orogens can be divided into simple and composite types. Simple orogens are represented by the Pyrenees and the Alps, and are characterized by narrow linear shapes in plain view and symmetric structures in cross-section, are free of arc magmatism, and are associated with the Mississippi Valley Valley-type Pb-Zn and orogenic gold deposits. The mineral deposits that form in these simple collisional orogens are generally related to processes that occur in the middle and upper crust. In contrast, composite orogens, as exemplified by the Zagros-Iranian and Himalayan-Tibetan Plateaus, are associated with broad orogenic plateaus in plain view and asymmetrical structures in cross-section, record extensive arc magmatism in continental margins, and are associated with a variety of deposit types including carbonatite-related rare earth element (REE), porphyry Cu-Mo, orogenic Au, Mississippi Valley type Pb-Zn, and detachment-fault-related polymetallic deposits. Although the subduction of Neo-Tethys oceanic crust occurred before the creation of simple collisional orogens in the Pyrenees and the Alps, these areas do not show the record of continental arc magmatism. In contrast, the composite collisional orogens are associated with the development of huge continental margin arcs prior to continental subduction, and the subduction was followed by reactivation of the subduction-modified arc lithospheric material, generating the ore-forming systems in these regions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Four types of tin mineralization in the Shihuiyao deposit formed at 145–150 Ma. • Hydrothermal cassiterite from the shallow epithermal veins can be discriminated from those from magmatic settings due to lower Mn, Nb, Ta, and REE and higher W contents. • The variations in texture and components of cassiterites in Shihuiyao deposits may not only record the processes of enrichment and transportation of rare metals during their magmatic–hydrothermal evolution but also be used as an effective exploration tool. The Shihuiyao giant Rb deposit in association with Nb–Ta–Be–Sn occurs within the Southern Great Xing'an Range tin belt known for its Sn, W, Cu, Ag, and base-metal deposits. The trace element compositions of four types of cassiterites hosted in the granite, greisen, unidirectional solidification texture (UST) quartz layer, and the hydrothermal quartz vein, respectively (abbreviated as Cst-I to Cst-IV) were measured by laser ablation inductively coupled plasma mass spectrometry and electron probe microanalysis to establish chemical criteria for the application of cassiterite as a useful geological tracer mineral. In situ U–Pb dating of Cst-I, Cst-III, and Cst-IV yielded Tera–Wasserburg intercept ages of 150.3±5.2, 145.8±4.6, and 146.9±3.5 Ma, respectively. These ages are consistent with the previously published monazite and columbite U–Pb ages of 150.2–141.0 Ma for the Shihuiyao ore-bearing granites, indicating a genetic relationship between granite magmatism and Ta–Nb–Sn mineralization. The composition of the studied cassiterites within the whole magmatic–hydrothermal evolution process yields some petrographic dissimilarities and geochemical trends from xenothermal to epithermal environments, which can be used to fingerprint the fluid evolution of the Shihuiyao deposit. For example, the magmatic cassiterites (Cst-I and Cst-II) are strongly enriched in Ta and yield low Nb/Ta ratios compared to the Cst-IV cassiterites from shallow hydrothermal veins. The occurrence of wodginite-group minerals and the highest W concentrations in cassiterite from the UST quartz layers suggests that the main enrichment in W is primarily controlled by magmatic fluid exsolution during the magmatic–hydrothermal transition stage. Additionally, hydrothermal cassiterite is generally lighter in color and characterized by complex internal oscillatory zoning with alternate dark (Cst-IVa) and light (Cst-IVb) bands. Cst-IVa cassiterites have similar W, Nb, and Ta contents but much higher Ti contents compared to Cst-IIIb cassiterites related to primary magmatic fluid, whereas Cst-IVb cassiterites exhibit sharply decreasing W but elevated Ti contents, suggesting pulsed exsolution of magmatic ore‑forming fluids and the involvement of external fluid in a distal open-fluid systems during the late mineralization stage. Therefore, the chemical variations of cassiterites are not only robust tracers pointing to magmatic–hydrothermal centers but also effective in discriminating the primary source of alluvial cassiterite and evaluating its metallogenic potential during a natural heavy mineral survey, supporting the use of cassiterite as an indicator mineral for exploration targeting. [ABSTRACT FROM AUTHOR]

The Cenozoic Mianning–Dechang (MD) rare earth element (REE) belt in eastern Tibet is an important source of light REE in southwest China. The belt is 270 km long and 15 km wide. The total REE resources are >3 Mt of light rare earth oxides (REO), including 3.17 Mt of REO at Maoniuping (average grade = 2.95 wt.%), 81,556 t at Dalucao (average grade = 5.21 wt.%), 0.1 Mt at Muluozhai (average grade = 3.97 wt.%), and 5764 t of REO at Lizhuang (average grade = 2.38 wt.%). Recent results from detailed geological surveys, and studies of petrographic features, ore-forming ages, ore forming conditions, and wallrock alteration are synthesized in this paper. REE mineralization within this belt is associated with carbonatite–syenite complexes, with syenites occurring as stocks intruded by carbonatitic sills or dikes. The mineralization is present as complex vein systems that contain veinlet, stringer, stockwork, and brecciated pipe type mineralization. Carbonatites in these carbonatite-related REE deposits (CARDs) are extremely rich in light REEs, Sr (>5000 ppm), and Ba (>1000 ppm), and have low Sr/Ba and high Ba/Th ratios, and radiogenic Sr–Nd isotopic compositions. These fertile magmas, which may lead to the formation of REE deposits, were generated by the partial melting of sub-continental lithospheric mantle (SCLM) that was metasomatized by REE- and CO 2 -rich fluids derived from subducted marine sediments. We suggest that this refertilization occurred along cratonic margins and, in particular, at a convergent margin where small-volume carbonatitic melts ascended along trans-lithospheric faults and transported REEs into the overlying crust, leading to the formation of the CARDs. The formation of fertile carbonatites requires a thick lithosphere and/or high pressures (>25 kbar), a metasomatized and enriched mantle source, and favorable pathways for magma to ascend into the overlying crust where REE-rich fluids exsolve from cooling magma. The optimal combination of these three factors only occurs along the margins of a craton with a continental root, rather than in modern subduction zones where the lithosphere is relatively thin. U–Pb zircon dating indicates that the Maoniuping, Lizhuang, and Muluozhai alkali igneous complexes in the northern part of the belt formed at 27–22 Ma, whereas the Dalucao complex in the southern part of the belt formed at 12–11 Ma. Biotite and arfvedsonite in Lizhuang and Maoniuping REE deposit have 40 Ar/ 39 Ar ages of 30.8 ± 0.4 Ma (MSWD = 0.98) and 27.6 ± 2.0 Ma (MSWD = 0.06), respectively. Biotitaion alteration in syenite and fenitization caused by the relatively amount of carbonatite on syenite and host rocks is the main alteration along the whole belt. Initial Sr (0.7059–0.7079), 143 Nd/ 144 Nd (0.5123–0.5127), and 207 Pb/ 204 Pb (15.601–15.628) and 208 Pb/ 204 Pb (38.422–38.604) isotopic compositions of fluorite, barite, celestite, and calcite in the MD belt are similar to those of the associated syenite and carbonatite. Given the relatively high contents of Cl, F, SO 4 2− , and CO 2 in the rocks of the complexes, it is likely that the REEs were transported by these ligands within hydrothermal fluids, and the presence of bastnäsite indicates that the REEs were precipitated as fluorocarbonates. Petrographic, fluid inclusion, and field studies of the ores indicate that bastnäsite and other REE minerals formed during the final stages (<300 °C) of the evolution of magmatic–hydrothermal systems in the belt. The mineralization formed from magmatic and meteoric fluids containing CO 2 derived from the decarbonation of carbonatite, as indicated by C–O isotopic values of hydrothermal calcite and bastnäsite (δ 13 C = −4.8 to −8.7 and δ 18 O = 5.8 to 12.5‰) and O–H isotopic values of quartz (330 °C) and arfvedsonite (260 °C), which correspond to fluid isotope compositions of δ 18 O = 0.3–9.8‰ and δD = −70.0 to −152.8‰ in the belt. This study indicates that formation the largest REE deposits are related to voluminous carbonatite–syenite complexes, compositionally similar ore-forming fluids, extensive alteration, multiple stages of REE mineralization, and tectonic setting. [ABSTRACT FROM AUTHOR]

The Tethyside orogen, a direct consequence of the separation of the Gondwanaland and the accretion of Eurasia, is a huge composite orogenic system that was generated during Paleozoic–Mesozoic Tethyan accretionary and Cenozoic continent–continent collisional orogenesis within the Tethyan domain. The Tethyside orogenic system consists of a group of diverse Tethyan blocks, including the Istanbul, Sakarya, Anatolide–Taurides, Central Iran, Afghanistan, Songpan–Ganzi, Eastern Qiangtang, Western Qiangtang, Lhasa, Indochina, Sibumasu, and Western Burma blocks, which were separated from Gondwana, drifted northwards, and accreted to the Eurasian continent by opening and closing of two successive Tethyan oceanic basins (Paleo-Tethyan and Neo-Tethyan), and subsequent continental collision. The Tethyan domain represents a metallogenic amalgamation across diverse geodynamic settings, and is the best endowed of all large orogenic systems, such as those associated with the Cordilleran and Variscan orogenies. The ore deposits within the Tethyan domain include porphyry Cu–Mo–Au, granite-related Sn–W, podiform chromite, sediment-hosted Pb–Zn deposits, volcanogenic massive sulfide (VMS) Cu–Pb–Zn deposits, epithermal and orogenic Au polymetallic deposits, as well as skarn Fe polymetallic deposits. At least two metallogenic supergroups have been identified within the eastern Tethyan metallogenic domain (ETMD): (1) metallogenesis related to the accretionary orogen, including the Zhongdian, Bangonghu, and Pontides porphyry Cu belts, the Pontides, Sanandaj–Sirjan, and Sanjiang VMS belts, the Lasbela–Khuzdar sedimentary exhalative-type (SEDEX) Pb–Zn deposits, and podiform chromite deposits along the Tethyan ophiolite zone; and (2) metallogenesis related to continental collision, including the Gangdese, Yulong, Arasbaran–Kerman and Chagai porphyry Cu belts, the Taurus, Sanandaj–Sirjan, and Sanjiang Mississippi Valley-type (MVT) Pb–Zn belts, the Southeast Asia and Tengchong–Lianghe Sn–W belts or districts, the Himalayan epithermal Sb–Au–Pb–Zn belt, the Piranshahr–Saqez–Sardasht and Ailaoshan orogenic Au belts, and the northwest Iran and northeastern Gangdese skarn Fe polymetallic belts. Mineral deposits that are generated with tectonic evolution of the Tethys form in specific settings, such as accretionary wedges, magmatic arcs, backarcs, and passive continental margins within accretionary orogens, and the foreland basins, foreland thrust zones, collisional sutures, collisional magmatic zones, and collisional deformation zones within collisional orogens. Synthesizing the architecture and tectonic evolution of collisional orogens within the ETMD and comparisons with other collisional orogenic systems have led to the identification of four basic types of collision: orthogonal and asymmetric (e.g., the Tibetan collision), orthogonal and symmetric (Pyrenees), oblique and symmetric (Alpine), and oblique and asymmetric (Zagros). The tectonic evolution of collisional orogens typically includes three major processes: (1) syn-collisional continental convergence, (2) late-collisional tectonic transform, and (3) post-collisional crustal extension, each forming distinct types of ore deposits in specific settings. The resulting synthesis leads us to propose a new conceptual framework for the collision-related metallogenic systems, which may aid in deciphering relationships among ore types in other comparable collisional orogens. Three significant processes, such as breaking-off of subducted Tethyan slab, large-scale strike-slip faulting, shearing and thrusting, and delamination (or broken-off) of lithosphere, developed in syn-, late- and post-collisional periods, repsectively, were proposed to act as major driving forces, resulting in the formation of the collision-related metallogenic systems. Widespread appearance of juvenile cr [ABSTRACT FROM AUTHOR]

[Display omitted] • Two fundamental types of collisional orogens have been proposed. • Cold orogens are characterized by brittle fault systems and limited magmatism. • Hot orogens are characterized by ductile flow and widespread partial melting. • MVT Pb–Zn and orogenic gold deposits can occur in both cold and hot orogens. • Porphyry Cu deposits are only associated with hot orogens. It is commonly believed that the thermal regime of collisional orogens evolves from cold to hot with time. Here, we compare the Alpine and Himalayan-Tibetan orogens in terms of their thermal regimes recorded in metamorphic rocks, volcanic suites and related xenoliths, and main mineralization types. The results highlight the fact that the Alpine orogen mostly remained in a relatively cold regime from oceanic subduction to post collision stages. In contrast, most of the Himalayan-Tibetan Plateau rapidly reached and was maintained in a relatively hot regime during the whole course of the collision, except for narrow plate boundary domains. We therefore propose that the thermal regime of collision is inherent to a given geodynamic setting, and that the Alpine and Himalayan-Tibetan orogens represent two fundamental types of collisional orogens, cold and hot, respectively. The main mineral deposit types within collisional orogen include Mississippi Valley type Pb–Zn, orogenic gold, and porphyry Cu deposits. The Mississippi Valley type Pb–Zn and orogenic gold deposits can occur in both cold and hot orogens but porphyry Cu deposits are only associated with hot orogens. Major factors that influence the thermal regime of collisional systems include the rate of continental subduction, the rheology of the underlying lithospheric mantle, the thickness of the overlying lithosphere and radiogenic heat production. Here we propose the removal of suborogenic mantle lithosphere and upwelling of asthenosphere also plays an important role on the thermal structure of collision zones. These processes disturbe the thermal balance of the orogens and cause widespread partial melting of the crust, resulting in the formation of magma-related deposits (i.e., granite-related W-Sn deposits and porphyry Cu deposits). We further give a brief overview of other examples around the globe, such as Pyrenees and Caledonides that reperesent cold orogens versus Variscan and Zagros-Iranian Plateau exemplifying hot orogens. [ABSTRACT FROM AUTHOR]

Abstract: Mineral deposits associated with continental collision are abundant in many orogenic systems. However, the metallogenesis of collisional orogens is often poorly understood, due to the lack of systematic studies on the genetic links between collisional processes and ore formation in collisional orogenic belts. This paper reviews the key metallogenic settings and resultant collision-related ore deposits in the Tibetan Orogen, created by Indo-Asian collision starting in the early Cenozoic. The resulting synthesis leads us to propose a new conceptual framework for Tibetan metallogenic systems, which may aid in deciphering relationships among ore types in other comparable collisional belts. This framework includes three principal metallogenic epochs in the Tibetan orogen, and metallogenesis in: (1) a main-collisional convergent setting (∼65–41 Ma); (2) a late-collisional transform structural setting (∼40–26 Ma); and (3) a post-collisional crustal extension setting (∼25–0 Ma), each forming more than three distinct types of ore deposits in the Tibetan orogen. The main-collisional metaollognesis took place in a convergent setting, i.e., a collisional zone, characterized by collision-related crustal shortening and thickening, associated syn-peak metamorphism and two distinct magmatic series (Paleocene–Eocene crust-derived low-fO2 granitoids generated by crustal anatexis and Eocene high-fO2 granitoids formed by MASH processes at the base of the Tibetan crust). Metallogenesis during this period formed Sn–W–rare metal deposits related to the low-fO2 granitoids, skarn-hosted Cu–Au polymetallic deposits related to high-fO2 granitoids, and orogenic-type Au deposits formed by CO2-dominant metamorphic fluids. Late-collisional metallogenesis occurred mainly in a transform structural setting dominated by Cenozoic strike-slip faulting, shearing, thrust systems, and associated potassic magmatism in eastern Tibet, and formed the most economically-significant metallogenic province in the orogen. Four significant ore-forming systems are recognized in the transform zone: porphyry Cu–Mo–Au systems associated with potassic adakitic melts and controlled by Cenozoic strike-slip faults; orogenic-type Au systems related to large-scale left-slip ductile shearing; REE-bearing systems associated with lithospheric mantle-derived carbonatite–alkalic complexes; and Zn–Pb–Cu–Ag systems related to basinal brines and controlled by Cenozoic thrust structures and subsequent strike-slip faults developed in the Tertiary foreland basin. Post-collisional metallogenesis occurred in a crustal extension setting, characterized by lithospheric mantle thinning or delamination at depth, crustal shortening at a lower structural level and synchronal extension at shallower levels. The resulting ore-forming systems include: (1) porphyry Cu–Mo ore systems related to high-K adakitic stocks derived from the newly-formed thickened mafic lower-crust; (2) vein-type Sb–Au ore systems controlled by the south Tibetan detachment system (STDs) and the metamorphic core complex or thermal dome intruded by lecuogranite intrusions; (3) hydrothermal Pb–Zn–Ag ore systems controlled by the intersections of N–S-striking normal faults with E–W-trending thrust faults; and (4) spring-type Cs–Au ore systems related to geothermal activity driven by partial melting of the upper crust. Associated ore deposits lie mostly within the mid-Miocene Gangdese tectono-magmatic belt, in which the scavenging role of fluids derived from evolved magma systems or dewatering of rift basins, and finally discharging at intersections of the orogen-transverse and -parallel faults are extremely important for formation of the low-temperature hydrothermal deposits. Based on the synthesis of deposits in the Tibetan orogen and comparison with the metallogenesis of other orogenic systems, a more complete classification for these collision-related deposits can be proposed. [Copyright &y& Elsevier]

Abstract: Tectonically, the Sanjiang Tethyan Metallogenic Domain (STMD) is located within the eastern Himalayan–Tibetan Orogen in the Sanjiang Tethys, southwestern China. Although this metallogenic domain was initiated in the Early Palaeozoic, extensive metallogenesis occurred in the Late Palaeozoic, Late Triassic and Himalayan (Tertiary) epochs. Corresponding tectonic settings and environments in the domain are: an arc-basin system related to the subduction of the Palaeo-Tethyan oceanic slabs; a post-collision crustal extension setting caused by the lithospheric delamination or slab breakoff underneath the Sanjiang Tethys during the Late Triassic; large-scale strike-slip faulting and thrusting systems due to the Indo-Asian continent collision since the Palaeocene. In this metallogenic domain important gold, copper, base metals, rare metals and tin ore belts, incorporating a large number of giant deposits, were developed. The main types of deposits include: (1) porphyry copper deposits, controlled by a large-scale strike-slip fault system, (2) VHMS deposits, mainly occurring in intra-arc rift basins and post-collision crustal extensional basins, (3) shear-zone type gold deposits in the ophiolitic mélange zone along the thrusting–shearing system, (4) hydrothermal silver-polymetallic deposits in the Triassic intra-continental rift basins and Tertiary strike-slip pull-apart basins, and (5) Himalayan granite-related greisen-type tin and rare-metallic deposits. Within the metallogenic epochs of the Late Palaeozoic to Cenozoic, the styles and types of the ore deposits changed from VHMS types in the Late Palaeozoic through exhalative-sedimentary type deposits in the Late Triassic, to porphyry-type copper deposits, shear-zone type gold deposits, hydrothermal vein-type silver-polymetallic deposits, greisen-type tin and rare-metal deposits in the Cenozoic. Correspondingly, ore-forming metals also changed from a Pb–Zn–Cu–Ag association through Ag–Cu–Pb–Zn, Fe–Ag–Pb and Ag–Au–Hg associations, to Ag–Cu–Pb–Zn, Cu–Mo, Au, Sn, and Li–Rb–Cs–Nb–Zr–Hf–Y–Ce–Sc associations. [Copyright &y& Elsevier]

The article focuses on a research paper discussing the geodynamics and metallogeny of the Eastern Tethyan metallogenic domain (ETMD) in China. It mentions that the ore deposits within ETMD include porphyry copper?molybdenum?gold, granite-related tin?tungsten and podiform chromite. It also suggests that breaking-off of subducted Tethyan slab, strike-slip faulting, shearing and thrusting and delamination of lithosphere resulted in the formation of the collision-related metallogenic systems.

The Shimensi tungsten polymetallic deposit, situated in the Dahutang ore field, South China, is one of the largest tungsten deposits in the world, with an estimated WO 3 reserve of 0.74 million tons. Coarse-grained porphyritic biotite granite (CPBG), fine-grained porphyritic biotite granite (FPBG), fine-grained biotite granite (FBG) and biotite granite porphyry (BGP) are all ore-related, but their diagenetic relationships and contributions to W-Cu-Mo mineralization are still in dispute. LA-ICP-MS monazite U-Pb dating of the CPBG, FPBG, FBG and BGP yield emplacement ages of 147.9 ± 1.1 Ma, 146.4 ± 1.1 Ma, 138.6 ± 0.98 Ma and 142.8 ± 1.7 Ma, respectively. Whole-rock geochemical results indicate that the four granites should be classified as S-type granites, but BGP has distinct features transitional between S- and I-type granites. They were possibly generated by partial melting of upper crustal pelites and basic volcanic rocks with different proportion from the Neoproterozoic Shuangqiaoshan Group in the source. Proportional variation in the magmatic source (clay and basic basalts) induces the change of geochemical compositions of the Shimensi granites. Geochemical characteristics suggest that they were derived from two magma chambers (the CPBG, FPBG and FBG vs. the BGP) and experienced different evolutionary processes and different degree of magmatic differentiation during magmatic evolution. Chondrite-normalized REE patterns for the four granites display low total REE contents, variable and strongly enriched LREE relative to HREE and medium-strong negative Eu anomalies. They are enriched in Rb, Th, U, Ta and depleted in Ba, Nb, Sr, P, Ti. Biotites are iron-rich and aluminum-poor, and can be classified as ferro-biotite (CPBG, FPBG and FBG) and siderophyllite (BGP). The partial melting of tungsten-rich metasediments of the Shuangqiaoshan Group and high degree of fractional crystallization led to enrichment in tungsten in the magma suites. Oxygen fugacities of the CPBG and FPBG declined from early (most above the NNO buffers) to late stages of fractional crystallization (between the NNO and QFM buffers) because of the higher degree of magmatic differentiation in the late stages. In the early stages of fractionation, tungsten accumulated in the residual melts rather than partitioning into accessory minerals. In the late stages, lower oxygen fugacities and high fluorine contents promoted the removal of tungsten from the residual magma into reduced hydrothermal fluids. On the other hand, the FBG and BGP remained constant (above the NNO buffers) over the entire process of crystallization owning to the stable degree of magmatic differentiation, promoting retention of tungsten in the melt and resulting in low grade tungsten mineralization. Tungsten mineralization in the Shimensi deposit is greatly controlled by the redox states of the associated magma. The two porphyritic granites (the CPBG and FPBG) are most likely the main contributors of tungsten, while the FBG and BGP are mainly responsible for copper and molybdenum in the Shimensi deposit. Prolonged multiphase magmatism and prolonged W-Cu-Mo mineralization play important roles in the formation of Shimensi large tungsten polymetallic deposit. • The four ore-related granites in the Shimensi deposit formed at 138.6–147.9 Ma. • The four granites were derived from two magma chambers. • The CPBG and FPBG are responsible for tungsten, while the FBG and BGP are responsible for copper and molybdenum. [ABSTRACT FROM AUTHOR]

[Display omitted] • The adakite-like ore-forming tonalites in Saindak were derived from partial melting of a thickened juvenile lower crust. • The input of mantle-derived K-rich melts into the juvenile lower crust drove the formation of the Saindak porphyry deposit. • The large porphyry deposits in the Chagai belt developed in a thickened crustal setting. The subduction-related Saindak porphyry Cu-Au deposit lies in the western segment of the Chagai belt, Pakistan. This deposit consists of three orebodies (south, east, and north), and each orebody is centered around ore-forming tonalite and crosscut by diorite porphyry dikes and andesite dikes. The three orebodies show similarities in the alteration zones, mineralization styles, and metallic associations. K-silicate, sericite-chlorite, quartz-sericite, and chlorite-epidote alteration assemblages are zoned around the porphyry intrusions. Laser ablation-inductively coupled plasma–mass spectrometry (LA-ICP–MS) U-Pb zircon geochronology yields ages between 22.2 ± 0.2 and 21.8 ± 0.3 Ma for the ore-forming tonalite, 22.1 ± 0.2 Ma for the diorite porphyry, and 22.2 ± 0.4 Ma for the andesite. Molybdenite re-Os dating yields an age of 22.2 ± 0.2 Ma for mineralization. The new geochemical compositions of magmatic rocks indicate that the andesite and K-rich diorite porphyry originated from partial melting of the asthenospheric mantle and metasomatized lithospheric mantle underneath the Chagai belt, respectively. The adakite-like ore-forming tonalites were derived from partial melting of a thickened juvenile lower crust, implying that the ore-forming materials in the Saindak deposit may be closely related to the lower crust. The injection of melts represented by the K-rich diorite porphyry would have increased the oxygen fugacity and water content of melts derived from the juvenile lower crust, making them favorable for the formation of the Saindak deposit. Combined with previously published data, we suggest that large porphyry Cu-Au deposits in the Chagai belt all developed in the thickened crust. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zircon U-Pb analyses yield ages of 400.2–377.1 Ma for the Xiaotuergen granitoids. • The Xiaotuergen granitoids are I-type granitoids, generated in a continental arc setting. • The Xiaotuergen granitoids were most likely generated by the partial melting of the juvenile lower crust with some interaction of lithospheric mantle-derived materials. • The parental magma of the fertile granodiorite porphyry was more oxidized and had a higher water content than those of the barren intrusions. The Xiaotuergen Cu deposit is the first Cu deposit described in the Northern Chinese Altai Orogen, Xinjiang, NW China. The multiple phases of granitic intrusions occur in the Xiaotuergen region, including the intrusions of granodiorite porphyry, granite porphyry, and biotite monzogranite. Among these types of intrusions, Cu mineralization is considered to be closely related to the early Hercynian granodiorite porphyry. However, the precise emplacement ages, petrogenesis, redox states, and tectonic setting of the three Xiaotuergen granitoids and the relationship between these granitoids and mineralization was unclear. To resolve these issues, zircon U–Pb dates, zircon in situ trace element concentrations, Hf isotopic compositions, apatite in situ major element concentrations, and whole-rock geochemistry were determined in this study. Three different intrusive phases are recognized within the district; in order of deceasing age, these phases are biotite monzogranite, granodiorite porphyry, and granite porphyry, which have the ages of 400.2 ± 1.6 Ma to 399.6 ± 2.4 Ma, 390.3 ± 1.6 Ma to 377.1 ± 1.6 Ma, 381.0 ± 2.0 Ma to 378.7 ± 1.2 Ma, respectively, suggesting that they were emplaced during the Early-Middle Devonian. Geochemical data show that these intrusions are metaluminous to weakly peraluminous (A/CNK = 0.91–1.28), calc-alkalic to shoshonitic I-type granitoids. The two Harker plot trends reveal derivation from two magma sources (biotite monzogranite vs granodiorite porphyry and granite porphyry) that experienced different evolutionary processes. Multiple indicators, including the zircon Ce4+/Ce3+ ratio and oxygen fugacity (log f O 2) values, apatite Mn oxybarometer, and whole-rock Fe 2 O 3 /FeO ratio, consistently indicate that the parental magma of the fertile granodiorite porphyry was more oxidized than that of the two barren intrusions (biotite monzogranite and granite porphyry). Furthermore, apatite grains from the fertile granodiorite porphyry have higher Cl contents and Cl/F ratios than those of the ore-barren biotite monzogranite and granite porphyry, which may have resulted from the higher water content of the parental magma and increased lithospheric mantle-derived fluid involvement in their generation. Thus, higher Cl/F ratios of apatite can be used to discriminate fertile granitoid intrusions that host Cu mineralization in the Northern Altai orogen. Zircon Hf isotopic compositions show widely ranging and mostly positive ε Hf (t) values (−4.2 to +11.4, mainly concentrated between +2 and +8). These isotope characteristics in combination with young zircon T DM C (Hf) ages (655–1,659 Ma; mainly concentrated between 850 Ma and 1250 Ma) indicate that the Xiaotuergen granitoids were most likely derived from the partial melting of juvenile lower crust, with some interaction of mantle materials from the underlying mantle wedge. The three Xiaotuergen granitoids were enriched in light rare earth elements and large ion lithophile elements, depleted in heavy rare earth elements, and showed negative Nb, Ta, Sr, P, and Ti anomalies, displaying typical arc geochemical affinities. Combined with the regional tectonic evolution, we propose that the Xiaotuergen granitoids were generated in a continental arc setting associated with subduction processes, which were the products of syn -accretion orogenic processes. [ABSTRACT FROM AUTHOR]

The northeastern Gangdese Pb–Zn–Ag–Fe–Mo–W polymetallic belt (NGPB), characterized by skarn and porphyry deposits, is one of the most important metallogenic belts in the Himalaya–Tibetan continental orogenic system. This belt extends for nearly four hundred kilometers along the Luobadui–Milashan Fault in the central Lhasa subterrane, and contains more than 10 large ore deposits with high potential for development. Three major types of mineralization system have been identified: skarn Fe systems, skarn/breccia Pb–Zn–Ag systems, and porphyry/skarn Mo–Cu–W systems. In this study, we conducted a whole-rock geochemical, U–Pb zircon geochronological, and in situ zircon Hf isotopic study of ore-forming rocks in the NGPB, specifically the Jiangga, Jiaduopule, and Rema skarn Fe deposits, and the Yaguila Pb–Zn–Ag deposit. Although some of these deposits (porphyry Mo systems) formed during the post-collisional stage (21–14 Ma), the majority (these three systems) developed during the main (‘soft collision’) stage of the India–Asia continental collision (65–50 Ma). The skarn Fe deposits are commonly associated with granodiorites, monzogranites, and granites, and formed between 65 and 50 Ma. The ore-forming intrusions of the Pb–Zn–Ag deposits are characterized by granite, quartz porphyry, and granite porphyry, which developed in the interval of 65–55 Ma. The ore-forming porphyries in the Sharang Mo deposit, formed at 53 Ma. The rocks from Fe deposits are metaluminous, and have relatively lower SiO 2 , and higher CaO, MgO, FeO contents than the intrusions associated with Mo and Pb–Zn–Ag mineralization, while the Pb–Zn–Ag deposits are peraluminous, and have high SiO 2 and high total alkali concentrations. They all exhibit moderately fractionated REE patterns characterized by lower contents of heavy REE relative to light REE, and they are enriched in large-ion lithophile elements and relatively depleted in high-field-strength elements. Ore-forming granites from Fe deposits display 87 Sr/ 86 Sr (i) = 0.7054–0.7074 and ε Nd(t) = − 4.7 to + 1.3, whereas rocks from the Yaguila Pb–Zn–Ag deposit have 87 Sr/ 86 Sr (i) = 0.7266–0.7281 and ε Nd(t) = − 13.5 to − 13.3. In situ Lu–Hf isotopic analyses of zircons from Fe deposits show that ε Hf(t) values range from − 7.3 to + 6.6, with T DM (Hf) C model ages of 712 to 1589 Ma, and Yaguila Pb–Zn–Ag deposit has ε Hf(t) values from − 13.9 to − 1.3 with T DM (Hf) C model ages of 1216 to 2016 Ma. Combined with existing data from the Sharang Mo deposit, we conclude that the ore-forming intrusions associated with the skarn Fe and porphyry Mo deposits were derived from partial melting of metasomatized lithospheric mantle and rejuvenated lower crust beneath the central Lhasa subterrane, respectively. Melting of the ancient continental material was critical for the development of the Pb–Zn–Ag system. Therefore, it is likely that the source rocks play an important role in determining the metal endowment of intrusions formed during the initial stage of the India–Asia continental collision. [ABSTRACT FROM AUTHOR]

Abstract: The South China Region is rich in mineral resources and has a wide diversity of deposit types. The region has undergone multiple tectonic and magmatic events and related metallogenic processes throughout the earth history. These tectonic and metallogenic processes were responsible for the formation of the diverse styles of base and precious metal deposits in South China making it one of the resource-rich regions in the world. During the Proterozoic, the South China Craton was characterised by rifting of continental margin before eruption of submarine volcanics and development of platform carbonate rocks, and the formation of VHMS, stratabound copper and MVT deposits. The Phanerozoic metallogeny of South China was related to opening and closing of the Tethyan Ocean involving multiple orogenies by subduction, back-arc rifting, arc–continent collision and post-collisional extension during the Indosinian (Triassic), Yanshanian (Jurassic to Cretaceous) and Himalayan (Tertiary) Orogenies. The Late Palaeozoic was a productive metallogenic period for South China resulting from break-up and rifting of Gondwana. Significant stratabound base and precious metal deposits were formed during the Devonian and Carboniferous (e.g., Fankou and Dabaoshan deposits). These Late Palaeozoic SEDEX-style deposits have been often overprinted by skarn systems associated with Yanshanian magmatism (e.g., Chengmenshan, Dongguashan and Qixiashan). A number of Late Palaeozoic to Early Mesozoic VHMS deposits also developed in the Sanjiang fold belt in the western part of South China (e.g., Laochang and Gacun). South China has significant sedimentary rock-hosted Carlin-like deposits, which occur in the Devonian- to Triassic-aged accretionary wedge or rift basins at the margin of the South China Craton. They are present in a region at the junction of Yunnan, Guizhou, and Guangxi Provinces called the ‘Southern Golden Triangle’, and are also present in NW Sichuan, Gansu and Shaanxi, in an area known as the ‘Northern Golden Triangle’ of China. These deposits are mostly epigenetic hydrothermal micron-disseminated gold deposits with associated As, Hg, Sb+Tl mineralisation similar to Carlin-type deposits in USA. The important deposits in the Southern Golden Triangle are Jinfeng (Lannigou), Zimudang, Getang, Yata and Banqi in Guizhou Province, and the Jinya and Gaolong deposits in Guangxi District. The most important deposits in the Northern Golden Triangle are the Dongbeizhai and Qiaoqiaoshang deposits. Many porphyry-related polymetallic copper–lead–zinc and gold skarn deposits occur in South China. These deposits are related to Indosinian (Triassic) and Yanshanian (Jurassic to Cretaceous) magmatism associated with collision of the South China and North China Cratons and westward subduction of the Palaeo-Pacific Plate. Most of these deposits are distributed along the Lower to Middle Yangtze River metallogenic belt. The most significant deposits are Tonglushan, Jilongshan, Fengshandong, Shitouzui and Jiguanzui. Au–(Ag–Mo)-rich porphyry-related Cu–Fe skarn deposits are also present (Chengmenshan and Wushan in Jiangxi Province and Xinqiao, Mashan-Tianmashan, Shizishan and Huangshilaoshan in Anhui Province). The South China fold belt extending from Fujian to Zhejiang Provinces is characterised by well-developed Yanshanian intrusive to subvolcanic rocks associated with porphyry to epithermal type mineralisation and mesothermal vein deposits. The largest porphyry copper deposit in China, Dexing, occurs in Jiangxi Province and is hosted by Yanshanian granodiorite. The high-sulphidation epithermal system occurs at the Zijinshan district in Fujian Province and epithermal to mesothermal vein-type deposits are also found in the Zhejiang Province (e.g., Zhilingtou). Part of Shandong Province is located at the northern margin of the South China Craton and the province has unique world class granite-hosted orogenic gold deposits. Occurrences of Pt–Pd–Ni–Cu–Co are found in Permian-aged Emeishan continental flood basalt (ECFB) in South China (Jinbaoshan and Baimazhai in Yunnan Province and Yangliuping in Sichuan Province). South China also has major vein-type tungsten–tin–bismuth–beryllium–sulphide and REE deposits associated with Yanshanian magmatism (e.g., Shizhuyuan and Xihuashan), important world class stratabound base metal–tin deposits (Dachang deposit), and the large antimony deposits (Xikuangshan and Woxi). During the Himalayan Orogeny, many giant deposits were formed in South China including the recently emerging Yulong and Gangdese porphyry copper belts in Tibet and the Ailaoshan orogenic gold deposits in Yunnan. [Copyright &y& Elsevier]