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Since the beginning of the 21st century, the geoscience research has been entering a significant transitional period with the establishment of a new knowledge system as the core and with the drive of big data as the means. It is a revolutionary leap in the research of geoscience knowledge discovery from the traditional encyclopedic discipline knowledge system to the computer-understandable and operable knowledge graph. Based on adopting the graph pattern of general knowledge representation, the geoscience knowledge graph expands the unique spatiotemporal features to the Geoscience knowledge, and integrates geoscience knowledge elements, such as map, text, and number, to establish an all-domain geoscience knowledge representation model. A federated, crowd intelligence-based collaborative method of constructing the geoscience knowledge graph is developed here, which realizes the construction of high-quality professional knowledge graph in collaboration with global geo-scientists. We also develop a method for constructing a dynamic knowledge graph of multi-modal geoscience data based on in-depth text analysis, which extracts geoscience knowledge from massive geoscience literature to construct the latest and most complete dynamic geoscience knowledge graph. A comprehensive and systematic geoscience knowledge graph can not only deepen the existing geoscience big data analysis, but also advance the construction of the high-precision geological time scale driven by big data, the compilation of intelligent maps driven by rules and data, and the geoscience knowledge evolution and reasoning analysis, among others. It will further expand the new directions of geoscience research driven by both data and knowledge, break new ground where geoscience, information science, and data science converge, realize the original innovation of the geoscience research and achieve major theoretical breakthroughs in the spatiotemporal big data research.

An intensive study of the geochemical characteristics (including the volatile elements Cl and S) of apatite associated with porphyry deposits was undertaken to address the debate about the crust- or mantle-derivation of their copper and gold and to better understand the controls on the transport of metals in magmatic fluids in post-subduction settings. New geochemical data on apatite reveal parameters to discriminate mineralized porphyry systems across Iran and western China (Tibet and Yunnan), from coeval barren localities across this post-subduction metallogenic belt. Apatites in fertile porphyries have higher Cl and S concentrations (reflecting water-rich crystallization conditions) than those from coeval barren ones. Our new isotopic data also indicate these volatiles are likely derived from pre-enriched sub-continental lithospheric mantle, metasomatized by previous oceanic subduction. This study demonstrates that refertilization of suprasubduction lithospheric mantle during previous collision events is a prerequisite for forming post-subduction fertile porphyries, providing an evidence-based alternative to current ore-enrichment models.

Magnesium isotopic compositions, along with new Sr–Nd–Pb isotopic data and elemental analyses, are reported for 12 Miocene tourmaline-bearing leucogranites, 15 Eocene two-mica granites and 40 metamorphic rocks to investigate magnesium isotopic behaviors during metamorphic processes and associated magmatism and constrain the tectonic-magmatic-metamorphic evolution of the Himalayan orogeny. The gneisses, granulites and amphibolites represent samples of the Indian lower crust and display large range in δ26Mg from −0.44‰ to −0.09‰ in mafic granulites, −0.44‰ to −0.10‰ in amphibolites, and −0.70‰ to −0.03‰ in granitic gneisses. The average Mg isotopic compositions of the granitic gneisses (−0.19 ± 0.34‰), mafic granulites (−0.22 ± 0.17‰) and amphibolites (−0.25 ± 0.24‰) are similar, indicating the limited Mg isotope fractionation during prograde metamorphism from granitic gneisses to mafic granulites and retrograde metamorphism from mafic granulites to amphibolites. The Eocene two-mica granites and Miocene leucogranites are characterized by large variations in elemental and Sr–Nd–Pb isotopic compositions. The leucogranites and two-mica granites have their corresponding (87Sr/86Sr)i varying from 0.7282 to 0.7860 and 0.7163 to 0.7191, (143Nd/144Nd)i from 0.511888 to 0.512040 and 0.511953 to 0.512076, 207Pb/204Pb from 15.7215 to 15.7891 and 15.7031 to 15.7317, 208Pb/204Pb from 38.8521 to 39.5286 and 39.2710 to 39.4035, and 206Pb/204Pb from 18.4748 to 19.0139 and 18.7834 to 18.9339. However, they have similar Mg isotopic compositions (−0.21‰ to +0.06‰ versus −0.24‰ to +0.09‰), which did not originate from fractional crystallization nor source heterogeneity. Based on hornblende/biotite/muscovite dehydration melting reaction and Mg isotopic variations in two-mica granites and leucogranites with the proceeding metamorphism, along with elemental discrimination diagrams, Eocene two-mica granites and Miocene leucogranites could be related to hornblende dehydration melting and muscovite dehydration melting, respectively. Mg isotopic compositions of Eocene two-mica granites become heavier compared to the source because of residues of isotopically light garnet in the source; while those of Miocene leucogranites become lighter because of entrainment of isotopically light garnet from the source region. Thus, a new model for crustal anatexis and Himalayan orogenesis was proposed based on the Mg isotope fractionation in the leucogranites and metamorphic rocks. This model emphasizes a successive process from Indian continental subduction to rapid exhumation of the Higher Himalayan Crystalline Series (HHCS). The former underwent high-temperature (HT) and high-pressure (HP) granulite-facies prograde metamorphism, which resulted in the hornblende dehydration melting and the formation of Eocene two-mica granites; while the latter experienced amphibolite-facies retrogression and decompression, which resulted in the muscovite dehydration melting and the formation of Miocene leucogranites.

The tectonic transition from subduction to collision is a fundamental process during orogenesis, yet the magmatic expression of this transition and related deep geodynamic processes remain unclear. This study focuses on a newly identified volcanic belt within the Moyun–Zaduo–Sulu area of the North Qiangtang Block and presents new zircon U-Pb data that indicate that this belt formed during the Middle Triassic (247–241 Ma), a time characterized by a regional transition from subduction to collisional tectonism. The volcanic belt is located to the south of a Permian to Early Triassic arc and is dominated by high-K calc-alkaline and peraluminous rhyolites. These rhyolites have low Mg#, Nb/Ta, and δEu values, contain low contents of Sr, have high Rb/Sr and whole-rock eNd(t) values, and show positive zircon eHf(t) values, all of which suggest that they formed from magmas generated by the dehydration melting of juvenile crustal material. The migration of Middle Triassic volcanism in this region was most likely caused by rollback of the subducting Longmucuo–Shuanghu Tethyan oceanic slab. Combining our new data with previously published results of numerical modeling of subduction–collisional processes and regional data from north-central Tibet yields insights into the magmatic expressions and related deep geodynamics of the transition from oceanic subduction to continental collision. This combination of data also suggests that variations in oxygen fugacity can be used as a proxy for the discrimination of magmatism related to subduction, the transition from subduction to collision, and collisional tectonism.

The genesis of high-silica igneous rocks is important for understanding the behavior of shallow magmatic systems. However, although many such studies have focused on the eruption of crystal-poor high-SiO2 rhyolites, the origin of high-silica granites (HSGs) has received comparatively little attention. Here, we present a detailed study of HSGs from the Narusongduo volcanic complex, Gangdese arc. Combining zircon U-Pb geochronology with stratigraphic investigations, we show that the Narusongduo magmatic system was constructed over a period of ≥3.7 Myr with or without lulls. On the basis of zircon textures and ages, diverse zircon populations, including antecrysts and autocrysts, are recognized within the HSGs and volcanic rocks. All of the igneous rocks within the Narusongduo volcanic complex have highly radiogenic Sr–Nd isotopic compositions. Our results indicate the presence of an andesitic magma reservoir in the upper crust at a paleodepth of ~8 km. Ubiquitous zircon antecrysts in the HSGs, combined with compositional similarities between the HSGs and evolved melts of the andesitic magma reservoir, indicate that the Narusongduo HSGs represent melts extracted from the shallow magma reservoir. In addition, our results suggest that magma recharge promoted the escape of high-silica melts to form the Narusongduo HSGs. This work presents an excellent case that kilometer-scale high-silica granites are the differentiated products from an upper crustal magma reservoir. It would make a contribution to contemporary debates concerning the efficiency of crystal–melt separation in upper crustal magmatic systems.

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.

Jinding is the third-largest known Mississippi Valley-type (MVT) Zn-Pb deposit. It is hosted by a dome containing a suite of complex breccias and sandstones with abundant gypsum and anhydrite. This study presents the results of new geologic mapping of the Jinding open pit and discusses the geology of the deposit in detail. Our new data support a previously proposed model where the deposit is hosted in an evaporite dome created by the diapiric migration of Late Triassic evaporites during Paleocene thrust loading. Nearly all of the mineralization in the deposit is hosted by evaporite diapir-related rocks, including diapiric breccias and laterally extruded material mixed with fluvial sandy sediments (limestone clast-bearing sandstones) and overlying gypsum-sand diapiric units (mainly clast-free sandstones). The new mapping determined that the currently light gray colored sandstones within the Jinding dome were originally red, with the bleaching being a response to calcite and pyrite alteration as a result of pre-ore interaction with hydrocarbons. The bleached sandstones host sphalerite and galena that replaced calcite, and Zn-Pb sulfides also occur in limestone breccias and gypsum-rich rocks as a result of replacement and open space-filling mineralizing processes. The Jinding deposit demonstrates that MVT Zn-Pb mineralization can be hosted by a variety of evaporite diapir-related rocks and indicates that dome structures and the presence of pre-ore hydrocarbons are both important for the formation of Zn-Pb mineralization.

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.

Amphibole fractionation during the early evolution of arc magmas has been widely inferred on the basis of distinctive geochemical fingerprints of the evolved melts, although amphibole is rarely found as a major mineral phase in arc volcanic rocks, so-called cryptic amphibole fractionation. Here, we present a detailed case study of xenoliths of amphibole-rich cumulate from the Zhazhalong intrusive suite, Gangdese arc, which enables an investigation of this differentiation process using a combination of petrological observations and in situ geochemical constraints. Evidence that the xenoliths represent fragments of igneous cumulates includes: (1) the presence of an amphibole-dominated crystal framework; (2) mineral and whole-rock Fe–Mg exchange coefficients; (3) rare-earth element patterns that are similar in the amphiboles and the xenoliths; (4) the compositions of basaltic to andesitic liquids in equilibrium with amphiboles; and (5) enrichment of the xenoliths in compatible elements and depletion in incompatible elements. The amount of trapped liquid based on La, Ce, and Dy abundances varies from ~12 to ~20%. Actinolitic cores within amphibole grains likely represent reaction between olivine precursor and hydrous melt, as evidenced by their high Cr and Ni contents. Amphibole thermometry and oxybarometry calculations indicate that crystal accumulation occurred over temperatures of 857–1014 °C, at mid-crustal pressures of 312 to 692 MPa and oxygen fugacity between 0.4 and 1.9 log units above the nickel–nickel oxide buffer. Quantification of the major-element compositions of the parent liquids indicates that the Zhazhalong amphibole cumulates crystallized from basaltic to andesitic magmas, probably with a shoshonitic affinity, and with SiO2 contents of 46.4–66.4 wt%. Appropriate partition coefficients, calculated using a parameterized lattice strain model and an empirical partitioning scheme, were employed to calculate the trace-element compositions of the liquids in equilibrium with amphibole. Our results confirm that Dy/Yb and Dy/Dy* ratios, which decrease with increasing degrees of differentiation, can be used as robust signatures of amphibole fractionation. This work presents a direct snapshot of the process of amphibole fractionation and provides a natural example of the hidden amphibole “sponge” in arc crust. In particular, this study also suggests that some appinites likely represent amphibole-rich cumulates, which may help to explain the genesis of other unusual but petrologically significant rocks.

The Tethyan domain from China to Iran hosts many important sediment-hosted Pb–Zn deposits but most have been poorly documented. This study summarizes the salient features of these deposits and discusses the type of ore, tectonic setting, and important ore controls, on the basis of new geological observations and previous publications. The Tethyan domain is characterized by the young and extensive Himalayan–Tibetan and Zagros orogens that formed through collisions between the India/Arabia and Eurasia continents since the Late Cretaceous or early Cenozoic. Abundant Mississippi Valley-type (MVT) and subordinate clastic-dominated (CD, also known as SEDEX) Pb–Zn deposits occur in this domain, including in central and eastern Himalayan–Tibetan orogen in China, the Indian passive margin in southern Pakistan, and various tectonic units of Iran. Economically important deposits contain 0.1–21 Mt Pb + Zn and have total metal resources of ~75 Mt with ~48% being oxidized ores. All major deposits known in this domain are MVTs (i.e., the Jinding, Huoshaoyun, Mehdiabad, and Angouran deposits). Mississippi Valley-type Pb–Zn deposits occur in continental-collision-related fold-and-thrust belts and forelands, where deposits are mostly located on the margin of the Eurasian continent, with some in the Indian and Arabian continental margins. Clastic-dominated Pb–Zn deposits occur in central Iran and southern Pakistan, hosted by deep-water siliciclastic sequences of the early Cambrian rifted continental margin of Gondwana and the Jurassic passive continental margin of India, respectively. The youngest mineralized rocks and ages constrain that some important MVT deposits (e.g., the Jinding, Chaqupacha, and Angouran deposits) were formed after a main phase of regional compression, during a regional, large-scale strike-slip or crustal-extension stage in a continental collision setting. In sense of lithologic structure, important ore controls for MVT deposits include evaporite diapir structure, carbonate/evaporite dissolution–collapse structure, pre-existing barite, and porous dolostone. Much of the primary sulfide ore in this domain has been oxidized by supergene processes. This is particularly pronounced in the newly discovered Huoshaoyun deposit, where almost all sulfides have been oxidized to smithsonite and cerussite. An understanding of tectonic setting, ore controls, and supergene processes is essential in exploring for MVT deposits in this domain.

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 WO3 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 Angouran deposit is the second-largest Zn–Pb deposit in Iran with 4.7 Mt sulfide ore (27.7% Zn, 2.4% Pb, and 110 g/t Ag) and 14.6 Mt nonsulfide ore (28.1% Zn, 4.4% Pb). Various models have been proposed to explain the genesis of sulfide ore in this deposit. Moreover, the mineralization type of its primary sulfide ores remains controversial. The major and trace element concentrations and sulfur isotopic composition of the two stages of sphalerite have been analyzed to constrain mineralization conditions and the genesis. The Angouran deposit, which contains discordant orebodies, is hosted in a Neoproterozoic/Cambrian schist-marble sequence. Two stages of sphalerite have been distinguished: early-stage (S1) red-brown sphalerite and late-stage (S2) honey-yellow sphalerite. Our result shows that, relative to the S2 sphalerite, the S1 sphalerite has higher contents of Fe, Mn, Co, Cu, Ag, Sn, Ga, Sb and In, but lower contents of As and Tl. Time-resolved depth profiles in these sphalerites determined by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analyses indicate that Fe, Cd, Co, Hg, Mn, Ge, and In are mainly present in solid solution and that Ag, Cu, Pb, As, Ni, Ga, Tl, Sb, and Sn are present in both solid solution and mineral inclusions. Correlation analyses reveal the occurrence of direct substitution mechanisms, such as Zn2+ ↔ (Fe2+, Cd2+) and 2Zn2+ ↔ Ge4++□ (vacancy) as well as coupled substitutions, such as 2Zn2+ ↔ Cu+ + Ga3+, 2Zn2+ ↔ (Cu+, Ag+) + Sb3+, 3Zn2+ ↔ Pb2+ + Tl+ + As3+, 4Zn2+ ↔ Pb2+ + 2As3++□(vacancy) or (Zn2+, Pb2+) ↔ Tl+ + As3+, and 4Zn2+ ↔ Cu+ + (Ga3+, In3+) + Sn4++□(vacancy). Geothermometer studies suggest that sphalerite in the Angouran deposit precipitated from a low-temperature (

The world-class Dahutang tungsten deposit is located within the Jiuling mining district of the central Jiangnan orogenic belt, Jiangxi Province, China. The deposit consists of a massive and gently dipping scheelite orebody that contains disseminated and veinlet-hosted mineralization located within a medium- to coarse-grained biotite granodiorite. The No. 1 ore block of the deposit also contains a 1.50–1.75 m thick shell-shaped pegmatoid zone that defines an inner contact zone between the mineralization-related porphyritic-like biotite granite and strongly mineralized biotite granodiorite that hosts the tungsten deposit. This pegmatoid zone contains very low concentrations of tungsten, but records the processes involved in the migration and enrichment of this element within the deposit. The pegmatoid contrasts with typical hydrothermal pegmatite-type ore in that it often contains megacrystic to giant alkali feldspar, quartz, and muscovite, and is spatially zoned in terms of unique texture and composition. The pegmatoid is zoned from a felsic aplite zone with a layered texture proximal to the intrusion through quartz–feldspar pegmatoid and feldspar–quartz pegmatoid zones to a final distal quartz-dominated zone. The quartz–feldspar pegmatoid is striped and contains megacrystic feldspars that have grown nearly perpendicular to the edge of the pegmatoid, indicating the direction of movement of early exsolved magmatic fluids. Cathodoluminescence imaging indicates that there are five types of quartz within the feldspar–quartz pegmatoid: megacrystic, large phenocrystic, small phenocrystic, matrix, and vein-hosted quartz. Each of these generations of quartz crystallized early, with the disseminated metasomatic quartz that crystallized during the middle stages of pegmatoid generation being followed by the uniform crystallization of late-stage, space-filling quartz. In situ oxygen isotopic and trace element analysis indicates that all of the quartz within the pegmatoid records accelerated growth, with the middle-stage disseminated metasomatic quartz associated with an increase in δ18Oquartz values, and the late-stage space-filling quartz associated with a decrease in δ18Oquartz values. All of this quartz contains elevated concentrations of alkali metals and has low Li/Al ratios (generally 10‰, reflecting the fact that the fluids that formed these minerals were of the peraluminous granite water (PGW). The trace element compositions of the samples analyzed during this study also indicate a drop in the pH of the pegmatoid-forming fluids over time. The quartz within the feldspar–quartz pegmatoid also contains melt and gas–liquid fluid inclusions, with the latter containing significant amounts of gas-phase CH4, indicating that the pegmatoid formed from low oxygen fugacity fluids. Our data indicate that the shell-shaped pegmatoid zone within the Dahutang No. 1 ore block formed from primary PGW exsolved from the hosting intrusion, with the pegmatoid recording the transition from magmatic to hydrothermal processes during the continuous but multi-stage evolution of the Dahutang deposit. The late-stage, high-temperature, water-rich, high δ18O, alkali-metal-rich, low oxygen fugacity, and acidic nature of the hydrothermal fluids that formed the deposit promoted the transportation and further deposition of tungsten.

The investigation of epigenetic carbonate-hosted Pb-Zn deposits from China and Europe in the Eastern and Western orogens of the Tethyan Domain, have provided a new perspective on the range of processes operating in this deposit class globally. However, improved metallogenic models require new constraints on the timing of mineralization throughout the Domain. To address this need, we applied Re-Os pyrite dating to the world class Irankuh Zn-Pb deposit, Iran. The Irankah deposit is located in the thrust belt of the Malayer-Esfahan Pb-Zn Metallogenic Belt (MEMB) in the Zagros Orogen, Iran. Mineralization is hosted by the Goushfil Main Fault and adjacent dolomitized limestones. The hydrothermal mineral assemblage comprises sphalerite, galena, pyrite, minor chalcopyrite and sulfosalt minerals, together with dolomite, barite and abundant quartz. Pyrite associated with main-stage sphalerite mineralization has low concentrations of 3 to 37 ng/g Re and 6 to 49 pg/g Os that are typical of low-level highly radiogenic (LLHR) sulfides. Nonetheless, vein and replacement pyrites from the Goushfil orebody yielded a 5-point isochron age of 66.5 ± 1.6 Ma that is interpreted as the main Zn-Pb mineralization age. The new mineralization age confirms an epigenetic origin for the Irankuh Zn-Pb deposit and supports an early onset for compressional deformation in the Zagros Orogen. The geochronological data support textural evidence that mineralization in veins occurred during regional compression in an active tectonic environment. Therefore the possibility that magmatic fluids and/or heat contributed to the mineralizing system should be incorporated into regional exploration models. Further work is required to test the extent to which epigenetic carbonate-hosted Pb-Zn deposits in the thrust and fold belt settings of the Central and Eastern Tethys differ from those in the Western Tethys and classic Mississippi Valley Type ore deposits.

Cenozoic high–Sr/Y shoshonites in western Yunnan, China, are spatially and temporally associated with porphyry deposits and mafic volcanic rocks that formed at a post–collisional setting. However, the petrogenesis of these rocks and the origins of the associated mineralization remain unclear. Here we present new geochemical data for the high–Sr/Y shoshonites and associated mafic microgranular enclaves (MMEs) in the Jinshajiang–Ailaoshan mineralization belt, which formed as a result of India–Asia collision during the Cenozoic. Both fertile and barren shoshonitic porphyries were emplaced during the Eocene–Oligocene (32–37 Ma) and are characterized by enrichment in large–ion lithophile elements (LILE), depletion in high field strength elements (HFSE), high K2O (4–6 wt%), Sr contents (674–1370 ppm), and low Y contents (7–18 ppm). The barren Zhanhe, Yongsheng, Songgui, and Jianchuan, and fertile Machangqing (Cu–Au–Mo mineralization) porphyry intrusions have variable zircon eHf(t) values of −6 to +9 and old TDM2 ages of 1433 to 900 Ma. However, the barren Shigu porphyry intrusion yields relatively positive zircon eHf(t) values (−4 to +8) and younger TDM2 ages (903–631 Ma). These features indicate that the Shigu intrusion was derived from late Permian juvenile lower crust, and the other high Sr/Y shoshonites were derived mainly from Neoproterozoic juvenile lower crust. Fertile and barren porphyries have variable whole–rock eNd(t) values (−5 to −0.7) and (87Sr/86Sr) i ratios (0.70595–0.70788) that are within the range of coeval mafic magmas in western Yunnan. The MMEs comprise mafic enclaves and andesitic enclaves that formed during the Eocene (34–35 Ma) and have spheroidal shapes, igneous textures and contain acicular apatites. This indicates that the MMEs are globules of coeval mafic magma that was injected into and mixed with the host shoshonitic magma. The enclaves show low TiO2 contents (0.7–0.8 wt%), high MgO (6–9 wt%), Cr (184–450 ppm) and Ni contents (98–157 ppm), positive LILE anomalies, marked negative HFSE anomalies, a narrow range of eNd(t) values (−1.2 to −0.6), and (87Sr/86Sr) i values of 0.70556–0.70635. The andesitic enclaves show adakitic geochemical affinities and have similar zircon eHf(t) values (−2.7 to +2.5) to the host porphyries, whereas, the mafic enclaves have relatively negative zircon eHf(t) values (−8.7 to +1.5), similar to enriched mantle. These evidences suggest the high−Sr/Y shoshonites were produced by partial melting of juvenile lower crust mixed with ultrapotassic or potassic mafic magmas as represented by the andesitic enclaves. The mafic enclave melts were derived from enriched mantle metasomatized by slab–derived fluids, which elevated the Mg#, Cr, Ni contents of the host porphyries at Machangqing, Zhanhe and Yongsheng. Zircon saturation temperatures (TZr) of the high–Sr/Y shoshonitic rocks range from 735 to 777 °C and indicate the shoshonites were derived mainly from water–fluxed melting of lower crust. The Manchangqing fertile intrusion had a high oxidation state (zircon Ce4+/Ce3+ = 38–180, average = 91) and was derived by mixing between juvenile lower–crustal melts and voluminous coeval lamprophyres. In contrast, the barren Jianchuan, Songgui, Shigu, Yongsheng and Zhanhe high–Sr/Y shoshonites formed by partial melting of juvenile lower crust and some mixing with mafic lavas, and are characterized by low oxygen fugacity (zircon Ce4+/Ce3+ = 0.5–77, average = 20). As such, we suggest the mafic magmas triggered water–fluxed, moderate–degree partial melting of the lower crust and caused amphibole breakdown during melting. This process could not provide enough water for the formation of porphyry Cu-Au deposits in western Yunnan, and therefore formed low–fO2, relatively low–H2O, and barren high–Sr/Y magmas. However, ultrapotassic magmas (e.g., lamprophyres) with high H2O are able to trigger intense water–fluxed, partial melting of metal–fertilized lower crust, which generated high–fO2, relatively high–H2O, fertile, high–Sr/Y shoshonitic magmas in this intracontinental setting.

The Mengshan district is located in the eastern segment of the Jiangnan Orogen in South China. Multi-phase intrusions were emplaced in this district, with the medium-grained porphyritic biotite granite and its marginal phase (fine-grained porphyritic biotite granite) genetically related to metal and non-metal mineralization. In this study, zircon U–Pb ages and trace elements, whole-rock geochemistry, and Nd isotopes were systematically analyzed for medium- and fine-grained porphyritic biotite granite in the Mengshan district, with the aim of elucidating the origin, evolutionary process, redox state, and mineralization competency of the studied granites. The Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA–ICP–MS) zircon U–Pb dating provided a weighted mean age of 226.6 ± 0.5 to 225.9 ± 0.5 Ma for the studied Mengshan granites, synchronous with the late-episode Triassic magmatism-mineralization in South China. The studied Mengshan granites are high-Si and -K, low-P, and weakly peraluminous, exhibiting features of highly evolved I-type granites. The detailed whole-rock geochemistry and Nd isotopes, and zircon trace elements and Hf isotopes demonstrated that the studied Mengshan granites were likely derived from disequilibrium melting of Proterozoic metamorphic basements that were composed of meta-igneous and metasediments and underwent fractional crystallization of plagioclase, K-feldspar, biotite, Fe-Ti oxide, zircon, and apatite. Low whole-rock K/Rb (2O3/FeO ratios (mostly < 0.5), zircon Ce4+/Ce3+ ratios (mostly lower than 90), and oxygen fugacity (below ΔFMQ + 1.4). The data in this study indicate that the Mengshan granites, especially the more evolved fine-grained porphyritic biotite granite, are favorable for W, Sn, Mo (

A recently discovered basanite dike in the Zaolin area of Jingdezhen, South China, contains mantle xenocrysts such as kink-banded olivines, olivines + orthopyroxenes assemblage, and chromites. In addition, polymorphic carbonates of the MgCO3–FeCO3 series occur as augens, either independently or interspersed with diopside and spinel in the matrix. The rock is characterized by high Cr and Ni contents, high whole-rock Mg# values (0.66–0.72), and high Ca/Al (0.72–1.03) and TFeO/MgO (1.1–1.3) ratios and is alkali-rich with Na2O > K2O. The trace-element partition patterns are similar to those of other basanites in eastern China as well as ocean island basalts. Whole-rock geochemical analyses show depleted Sr and Nd isotopic compositions (86Sr/87Sr=0.70358–0.703853, εNd=2.52–6.73). These data indicate that the rock has experienced negligible crustal contamination, should be derived from asthenospheric mantle, or mixed by the MORB with EMI/EMII mantle and have been carbonated. The calculated T–P conditions of the melt in equilibrium with xeno-olivine are 1160–1320°C at the mantle depth. The high Cr# values of the spinel xenocrysts indicate that the lithospheric mantle under the Jingdezhen area was probably relict Proterozoic mantle. The Ar–Ar plateau age and the isochron and inverse isochron ages for the matrix of the basanite are all 44 Ma. The basanite, as well as other alkaline basalt or lamprophyre dikes in southeastern China, formed in a rifting regime during the Eocene.

Current barriers hindering data-driven discoveries in deep-time Earth (DE) include: substantial volumes of DE data are not digitized; many DE databases do not adhere to FAIR (findable, accessible, interoperable and reusable) principles; we lack a systematic knowledge graph for DE; existing DE databases are geographically heterogeneous; a significant fraction of DE data is not in open-access formats; tailored tools are needed. These challenges motivate the Deep-Time Digital Earth (DDE) program initiated by the International Union of Geological Sciences and developed in cooperation with national geological surveys, professional associations, academic institutions and scientists around the world. DDE’s mission is to build on previous research to develop a systematic DE knowledge graph, a FAIR data infrastructure that links existing databases and makes dark data visible, and tailored tools for DE data, which are universally accessible. DDE aims to harmonize DE data, share global geoscience knowledge and facilitate data-driven discovery in the understanding of Earth's evolution., Deep-time Digital Earth is to promote data-driven discovery by harmonizing deep-time Earth data and creating ‘Geological Google’.

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.

Phanerozoic adakites typically represent modern analogues of Middle–Late Archean (3.5–2.5 Ga) tonalite–trondhjemite–granodiorite rocks (TTGs) due to their similarities in geochemical compositions. However, no Phanerozoic analogues have been reported for the Early Archean TTGs (>3.5 Ga), which are characterized by low Sr, Y and HREEs contents with low MgO and compatible elements contents, until recent years. The newfound Phanerozoic analogues have been defined as a new adakite subgroup named as “Jamaican–type adakites” (JTAs), and been regarded as the results of partial melting of subducted oceanic plateau crust. JTA–like magmas also occur in the Nuri complex, southern Tibet. We report whole–rock geochemical, Sr Nd isotopic data, zircon U Pb ages and in-situ Hf isotopic data for adakitic quartz diorites, quartz monzonites and JTA–like quartz porphyries in the Nuri complex. Zircon U Pb dating indicates that these rocks were emplaced in the Late Cretaceous at 93.5–92.1 Ma. Combined with the continuous variation trends of major and trace elements, the similarities in terms of whole–rock Sr Nd and zircon Hf isotopic compositions indicate that the three types of rocks are genetically related, while the quartz diorites should represent the relatively primitive melts. High MgO (5.00–5.41 wt%), Cr (138–159 ppm), Ni (65.9–96.8 ppm) contents and Mg# values (66–69), high e Hf (t) values (10.5–11.9), e Nd (t) values (3.7), and low ( 87 Sr/ 86 Sr) i values (0.7046–0.7050) indicate that the quartz diorites were derived from partial melting of subducted Neo–Tethyan oceanic slab, and subsequently underwent metasomatic reaction with the mantle wedge during their ascent. Quartz monzonites and JTA–like quartz porphyries were originated from quartz diorites by two stages of fractional crystallization. Low MgO and compatible elements contents of the quartz porphyries were caused by fractionation of hornblende, biotite, with minor magnetite and allanite, while low Sr contents and Sr/Y ratios were mainly controlled by plagioclase fractionation. This means that the JTA–like geochemical features of the quartz porphyries were generated by fractional crystallization from the adakites derived from partial melting of subducted slab, rather than directly derived from partial melting of subducted oceanic plateau. Therefore, various petrogenetic possibilities of the JTA–like magmas should be considered when using them as modern analogues.

The Neotethyan tectonics of the Zagros orogenic belt, SW Iran remains still hotly debated in comparing with its western counterparts. One major issue concerns the timing and nature of the Sanandaj-Sirjan magmatic-metamorphic belt (SSMB), which is made predominantly of metamorphic rocks and Jurassic to Early Cretaceous large plutonic complexes. The Alvand and Qory are two largest plutonic complexes locating in north-central and southern segments, respectively, of the SSMB. Careful LA-ICP-MS U/Pb analyses of the magmatic zircons from the Alvand plutonic complex reveal a smooth spectra, along which the concordant age increase gradually from 120 to 190 Ma; while that of Qory is step-like consisting of two stages, a Jurassic and a late Early Cretaceous ones, respectively. New geochemical data, combined with zircon Lu/Hf results suggest that (1) the Alvand granitoids mostly resulted from a long-lived, successive injection of juvenile-crust-sourced magma batches without obvious fractionation crystallization (FC); but (2) the two stages granitoids of the Qory complex both generated by FC of juvenile-crust-sourced magmas; and (3) the gabbros of the Alvand complex are geochemically of E-MORB-affinity while those of the Qory complex are typical continental arc mafic rocks. Previously published petrological and 40Ar/39Ar data have identified a broken, Jurassic to Early Cretaceous high-pressure metamorphic belt to the southwest of the SSMB, which likely represents the closed, southeastern equivalent of the northern Neotethyan Ocean, north of the Taurides-Anatolia-Armenia block. Thus, the SSMB in Iran, the Kapan belt in Caucasus, and the Serbo-Macedonian belt in northern Turkey form a huge Jurassic to Early Cretaceous continental margin arc system recording northeastwards subduction of the older Northern Neotethyan Ocean beneath Eurasia. The Albian-Cenomanian ophiolites such as Koy, Kermanshah, and Neyriz in Iran represent the eastern counterpart of the younger Southern Neotethyan Ocean, south of the Taurides-Anatolia-Armenia block. During the subduction of the Old Neotethys, an intraplate transform fault likely opened and generated a slab-window beneath the Alvand region, which provided a constant energy source to steadily heat the low crust. This model satisfactorily interprets the unusual geochronological framework and geochemistry of the Alvand complex.

The 1600 km-long Gangdese magmatic belt features extensive Paleocene–Eocene I-type intrusive rocks and coeval volcanic successions, which can be divided into Group I (~69–53 Ma), Group II (~53–49 Ma), and Group III (~49–43 Ma), corresponding to Neo-Tethyan slab rollback, Neo-Tethyan slab breakoff, and ongoing Indian-Asian collision, respectively. The magmas from these three groups show significant variations in geochemical and isotopic compositions, which provide the information of the growth of continental crust in southern Tibet. The most voluminous magmatism in the Gangdese belt occurred during ~53–49 Ma. High zircon saturation temperature (up to 800 °C) and Ti in zircon temperature (up to 980 °C) estimations suggest there is a period of thermal anomaly during ~53–49 Ma. Starting from ~53 Ma, magmas have increased K2O contents, and their zircons have decreased Th/U ratios, and Y and Yb contents. Zircons from Group II have the most heterogeneous Hf isotopic compositions (eHf(t) = −5.3 to 15.1). These are evident of ingress of asthenosphere mantle in the arc, extensive crustal melting, and magma mixing. Magma underplating during this time is the main mechanism for the growth of continental crust. With the Indian-Asian collision going on, the magmas in Group III show high Th/Y and La/Yb ratios and K2O contents, but significantly low Tzr and T(ti-zr) values (mostly below 750 °C). These features suggest the water-fluxed melting of early arc residues occurred in the late stage of growth of continental crust. The crust has been thickened and nearly mature at this stage. This study has great implication on understanding of growth of continental crust in orogenic belts.

Voluminous Jurassic granitoids within the Sanandaj–Sirjan Zone (SSZ) provide insight into the magmatic arc formed in the active margin of Eurasia. Here, we present new in situ zircon U–Pb, whole-rock major and trace element, and Sr–Nd isotopic data for the Gorveh Plutonic Complex (GPC) of the northwestern SSZ in Iran. Six samples from the plutons within the GPC yielded zircon U–Pb ages that range from 151 to 146 Ma. These plutons can be subdivided into two groups based on their geochemistry. Group 1 rocks (the Mobarak Abad diorites and the Gorveh gabbros and diorites) contain relatively high concentrations of the high field strength elements (HFSE; Nb, Ta, Zr, and Ti) and have low Th/Nb (0.20–0.56) and moderate Sm/Yb ratios (1.51–2.32), low (87Sr/86Sr)i values (0.70354–0.70622), and high eNd(t) values (2.3–5.4). These features indicate that the Group 1 rocks formed from magmas derived from a subduction-modified region of the subcontinental lithospheric mantle. The Group 2 plutons (the Bolban Abad granites and the Gorveh quartz monzonites) have A-type granites affinities, including high K2O + Na2O and Zr + Nb + Ce + Y concentrations, and high FeOtot/MgO and 10,000 × Ga/Al ratios. These A-type rocks are enriched in Rb, Th, and K, and depleted in Ba, U, Nb, Ta, Sr, P, and Ti. The Group 2 plutons have different Sr–Nd isotopic compositions to each other, indicating they were derived from different sources and record different igneous processes. The Gorveh quartz monzonites have high (87Sr/86Sr)i ratios (0.70552–0.70617), negative eNd(t) values (−1.1 to −5.4), and extremely low concentrations of MgO (0.32–0.35 wt%), suggesting they were derived from an igneous quartzo-feldspathic crustal source. In comparison, the Bolban Abad granites have positive eNd(t) values and contain high concentrations of SiO2 and low concentrations of MgO, suggesting that they formed from Group 1 magmas that subsequently underwent assimilation and fractional crystallization processes. Combining these new data with the results of previous research, we conclude that this Jurassic magmatism was the result of the formation of a slab window within the subducting Neo-Tethys slab, a process that caused the partial melting of overlying continental lithospheric material.

The concentrations and isotopic geochemistry of Li are potentially useful geochemical tracers of geological processes. To fully utilize Li isotopes as geochemical tracers, it is necessary to characterize the Li isotopic compositions of the various geological reservoirs. However, the Li isotopic composition of the juvenile lower crust is currently poorly constrained. Given that lithospheric architecture of the Tibetan Plateau includes Indian upper/lower crust, Tibetan upper/lower crust and juvenile lower crust, it is necessary to determine the Li isotopic composition for each geological endmember underneath southern Tibet. Among them, the juvenile lower crust was formed directly by underplating of mantle-derived basaltic magma, which is likely to be the critical factor to control the Cu-Au mineralization in southern Tibet and is responsible for crustal thickening beneath southern Tibet. Here, we report the Li concentration and isotopic composition of the juvenile lower crust in southern Tibet. Based on whole-rock major element, trace element, and Sr–Nd–Pb isotopic data, we infer that the Yeba basalts and Gangdese gabbros were derived from partial melting of metasomatized lithospheric mantle, and have compositions similar to the juvenile lower crust. In contrast, the Dianzhong andesites and Gangdese diorites originated from partial melting of the juvenile lower crust. Therefore, these units may be considered representative of the juvenile lower crust. The juvenile lower crust has Li concentrations of 7.1–37.2 ppm (mean = 15.4 ppm), consistent with the Li concentration for the lower crust (13 ppm). Li isotopic compositions (δ7Li) vary from +0.8‰ to +6.6‰ (mean = 3.0‰), similar to values for the EMI/EMII mantle. The Li isotopic compositions of the analyzed samples were not significantly affected by alteration, metamorphism, crustal assimilation, or magmatic differentiation, and therefore represent the isotopic compositions of the juvenile lower crust. The Li systematics of the juvenile lower crust may be attributed to partial melting of subcontinental lithospheric mantle that has undergone metasomatism by Li-rich fluids derived from subducted oceanic crust and marine sediments. Our study also demonstrates near-identical Li isotopic compositions for juvenile lower crust and metasomatized lithospheric mantle, resulting from the lack of Li isotope fractionation during basalt generation and differentiation.

Rare-earth deposits associated with intrusive carbonatite complexes are the world’s most important source of these elements (REE). One of the largest deposits of this type is Maoniuping in the Mianning-Dechang metallogenic belt of eastern Tibet (Sichuan, China). In the currently mined central part of the deposit (Dagudao section), REE mineralization is hosted by a structurally and mineralogically complex Late Oligocene (26.4 ± 1.2 Ma, 40Ar/39Ar age of fluorphlogopite associated with bastnasite) hydrothermal vein system developed in a coeval syenite intrusion. Low-grade stockworks of multiple veinlets and breccias in the lower part of the orebody grade upwards into progressively thicker veins (up to 12 m in width) that are typically zoned and comprise ferromagnesian micas (biotite to fluorphlogopite), sodium clinopyroxenes (aegirine to aegirine-augite), sodium amphiboles (magnesio-arfvedsonite to fluororichterite), K-feldspar, fluorite, barite, calcite, and bastnasite. The latter four minerals are most common in the uppermost 80 m of the Dagudao section and represent the climax of hydrothermal activity. Systematic variations in the fluid inclusion data indicate a continuous hydrothermal evolution from about 230–400 °C (fluid inclusions in feldspar, clinopyroxene, and amphibole) to 140–240 °C (fluid inclusions in bastnasite, fluorite, calcite). Hydrothermal REE transport was probably controlled by F−, (SO4)2−, Cl−, and (CO3)2− as complexing ligands. We propose that at Dagudao, silicate magmas produced orthomagmatic fluids that explored and expanded a fissure system generated by strike-slip faulting. Initially, the fluids had appreciable capacity to transport REE and, consequently, no major mineralization developed. The earliest minerals to precipitate were alkali- and Fe-rich silicates containing low levels of F, which caused progressive enrichment of the fluid in Ca, Mg, F, Cl, REE, (SO4)2−, and (CO3)2−, leading to the crystallization of aegirine-augite, fluororichterite, fluorphlogopite, fluorite, barite, calcite, and bastnasite gradually. Barite, fluorite, calcite, and bastnasite are the most common minerals in typical ores, and bastnasite generally postdates these gangue minerals. Thus, it is very probable that fluid cooling and formation of large amount of fluorite, barite, and calcite triggered bastnasite precipitation in the waning stage of hydrothermal activity.

The giant Zhuxi tungsten deposit is located in the Taqian-Fuchun Ore Belt in northeastern Jiangxi province, and genetically associated with the Zhuxi granitic stocks and dykes. Three mineralization-related granites including granite porphyry dykes (GP), biotite granitic stocks (BG), and white granitic dykes (WG), were identified in the Zhuxi deposit. SHRIMP zircon U–Pb analysis for the three granitic rocks present ages ranging from 153.5 ± 1.0 Ma to 150.4 ± 1.0 Ma. The BG mainly contains quartz, microcline, albite, biotite and muscovite with minor accessory minerals including zircon, apatite, monazite, Ti/Fe oxides, and dolerite. However, the WG is mainly composed of quartz, microcline and albite with minor muscovite and accessory minerals. The GP is a medium-grained porphyritic granite and its phenocrysts include quartz, alkali feldspar, muscovite and plagioclase. All the Zhuxi granites have high SiO2 content (71.97 wt%–81.19 wt%) and total alkali (3.25 wt%–9.42 wt%), and their valid aluminum saturation index (ASI) values show a wide range of 1.03 to 2.49. High Rb/Sr ratios, low Sr content (

Late Mesozoic magmatism is extensively developed in the eastern Jiangnan Orogen and is closely related to W, Mo, Cu, Au, and Sn mineralization. Late Mesozoic granitoids show various petrological and mineralizing features that vary spatially (northern Jiangxi Province and southern Anhui Province) and temporally (early stage: 154 to 136 Ma, late stage: 136 to 126 Ma). In this study, we analyzed zircon trace element data from four Late Mesozoic granitoids. Together with published zircon trace element data and biotite compositions from granitoids in the eastern Jiangnan Orogen and W–Sn, Mo and Cu deposits, we use these data to determine the magmatic redox state of the Late Mesozoic granitoids, which is useful in determining mineralization competency and is instructive during exploration. The results show that early stage granitoids of southern Anhui Province are oxidized, characterized by high zircon Ce4+/Ce3+ (median = 278), Ce/Nd (median = 17.1), and EuN/EuN* (median = 0.42) ratios, and high biotite Fe3+/Fe2+ ratios (median = 0.23) and XMg values (median = 0.48). The late stage granitoids of southern Anhui Province are relatively reduced, showing lower zircon Ce4+/Ce3+ (median = 49.7), Ce/Nd (median = 12.7), and EuN/EuN* (median = 0.16) ratios, and lower biotite Fe3+/Fe2+ ratios (median = 0.11) and XMg values (median = 0.38). The early stage granitoids of northern Jiangxi Province show a somewhat reduced redox state. They have comparatively low zircon Ce4+/Ce3+ (median = 17.28), Ce/Nd (median = 4.50), and EuN/EuN* (median = 0.17) ratios, and comparatively low biotite Fe3+/Fe2+ ratios (median = 0.07, N = 160) and XMg values (median = 0.35). The late stage granitoids of northern Jiangxi Province are strongly reduced, characterized by low zircon Ce4+/Ce3+ (median = 17.03), Ce/Nd (median = 0.72), and EuN/EuN* (median = 0.02) ratios, and low biotite Fe3+/Fe2+ ratios (median = 0.06) and XMg values (median = 0.25). Geochemical and isotopic data reveal that early stage granitoids in northern Jiangxi Province were sourced from Neoproterozoic metasedimentary rocks, whereas those in southern Anhui Province originated from Neoproterozoic volcanic–sedimentary sequences. The late stage granitoids in the eastern Jiangnan Orogen formed under an extensional regime and were generated by anatexis with various mantle inputs. The results suggest that early stage granitoids of southern Anhui Province have the potential for Cu (>1 Mt) and Mo (>0.3 Mt) mineralization, whereas late stage granitoids are related to W, Cu (

The giant Dahutang W–Cu–Mo ore field is one of the largest tungsten ore fields worldwide. Three main types of mineralization are developed at Dahutang, comprising veinlet-disseminated, hydrothermal breccia, and coarse quartz vein-type mineralization. In this study, precise muscovite 40Ar/39Ar ages and systematic in situ sulfur isotope compositions of sulfides from the Shimensi and Shiweidong deposits were presented to determine the ore-forming ages and mineralizing intrusions of the hydrothermal breccia type and coarse quartz vein-type mineralization, sources of sulfur in the mineralization, and tectonic setting of the Dahutang ore field. The precise muscovite 40Ar/39Ar dating suggested that the hydrothermal breccia in the Shimensi deposit formed at 142.0 ± 0.6 Ma and was triggered by the biotite granite porphyry (BGP), while the coarse quartz vein-type mineralization in the Shiweidong deposit formed at 136.1 ± 0.5 Ma and was caused by an early episode of coarse-grained porphyritic two-mica granite (CPTG; 144.2–137.5 Ma) and destroyed by the late episode of CPTG (130–128 Ma). The in situ sulfur isotope compositions of sulfides showed that the hydrothermal breccia type and the coarse quartz vein-type mineralization had a narrow range of sulfur isotope compositions (−3.38–+0.39‰), implying a magmatic origin for sulfur. The increased sulfur isotopes in the sulfides from early to late stages were probably caused by a reduction in the oxygen fugacity of ore-forming fluids in the hydrothermal breccia mineral system. The main W–Cu–Mo mineralization event at Dahutang occurred in the 146–136 Ma interval and was only associated with the early episode of magmatism (149–138 Ma), which coincided well with the Cu–Au–Mo–Fe mineral system in the neighboring Middle–Lower Yangtze River Metallogenic Belt (148–135 Ma). The late episode of magmatism (138–128 Ma), however, was commonly emplaced after the tungsten polymetallic mineralization and even destroyed early formed orebodies as ore-barren intrusions. Combined with the regional tectonic evolution, we proposed that the W–Cu–Mo mineralization and ore-related granites in the Dahutang ore field formed in a transitional setting from a compressional regime to an extensional regime.

Dating of bitumen can potentially constrain both the timing of mineralization and hydrocarbon deposition in hydrocarbon-bearing hydrothermal deposits. Here we report for the first time direct Sm-Nd dating on bitumen from the Erdaokan Ag-Pb-Zn deposit, a newly discovered, large, hydrocarbon-bearing hydrothermal deposit with 2964 kt of ore and 1535 t Ag with an average grade of 517 g/t Ag, 0.6 wt% Pb and 0.41 wt% Zn in the Back-Arc basin of NE Great Xing’an Range, NE China. Dating results show that Sm-Nd isochron age of four bitumen samples is 234.6 ± 1.2 Ma and an isochron age that includes three galena and four bitumen samples is 234.9 ± 1.4 Ma. In order to verify these ages, we performed Rb-Sr dating on pyrite and galena from the same deposit and U-Pb dating of zircon from the adjacent diorite porphyrite dike, which yielded ages of 232.9 ± 2.3 Ma and 234.2 ± 2.8 Ma, respectively. The highly concordant ages from multiple techniques confirms that bitumen Sm-Nd isotopic dating is reliable, and that the ages obtained in our study represent the hydrocarbon deposition as well as mineralization timing in the deposit. We conclude that, in the Duobaoshan metallogenic belt, the Erdaokan Ag-Pb-Zn deposit is the first identified large, Middle Triassic, hydrocarbon-bearing silver-lead–zinc deposit and is of great significance to the regional metallogenesis research and prospecting work in the Great Xing’an Range.

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.

In addition to well-known subduction processes, the collision of two continents also generates abundant ore deposits, as in the case of the Tibetan Plateau, which is the youngest and most spectacular collisional belt on Earth. During the building history of the Gangdese magmatic belt, several magmatic flare-up events developed, however, significant magmatic-hydrothermal lead–zinc mineralization dominantly accompanied the magmatism during the syncollisional period (~ 65–41 Ma). Based on integrated geochemical and isotopic data, we provide insights into the genesis and evolution of syncollisional magmas, and their implications for significant magmatic-hydrothermal lead–zinc mineralization. The Sr–Nd isotopic compositions of most syncollisional igneous rocks (87Sr/86Sr = 0.7034–0.7123; eNd(t) = − 9.0 to + 1.8) indicate a mixing origin between mantle-derived basaltic magmas and ancient crustal melts, and fractional crystallization is a fundamental mechanism by which syncollisional magmas evolve towards intermediate to silicic compositions. Most lead–zinc mineralization-related plutons are high silica (76.14% wt.% SiO2 on average), high oxygen fugacity (average ΔFMQ + 2.5) granites with highly evolved chemical signatures [average Eun/Eun* = 0.33, high Rb/Sr (average = 3.9)], and they represent the final products from primary magmas. Due to the contribution of ancient crustal melts to the genesis of mineralization-related parent magmas, the spatial distribution of Pb–Zn deposits within the northern Gangdese magmatic belt is controlled by the lithospheric architecture. In compressional environments, magmas have low evacuation efficiency and long magma chamber lifespan, which is favorable for basaltic parents evolved to high silica granites through sufficient fractional crystallization. This scenario contributes to our understanding of the significant magmatic-hydrothermal lead–zinc mineralization that occurred in the syncollisional period.

The Paleo-Tethyan tectonic evolution of north-central Tibet remains controversial, particularly regarding the nature and extension of associated sutures. The Yushu melange, located in the junction part of the western Jinshajiang, the southern Jinshajiang and the Ganzi–Litang sutures, is a key area to reveal the Paleo-Tethyan tectonics of this area. This study presents new geochronological and geochemical data for the Zhimenda volcanic suite of the Yushu Melange. These rocks preserve a record of back-arc magmatism along the northern margin of the North Qiangtang Block. The Zhimenda volcanics are composed of ignimbrite, basalt, and porphyritic tuff intercalated with terrigenous clastic rocks. Zircon 206 Pb/ 238 U ages of the ignimbrites indicate they formed at ~ 254 Ma. The basalts are relatively enriched in large-ion lithophile elements and depleted in high field strength elements. Their high MgO, Ni, and Cr contents, relatively high Sm/Yb and Rb/Nb values, and positive zircon e Hf (t) and bulk e Nd (t) values suggest they were derived from the partial melting of a depleted subcontinental lithospheric mantle source metasomatized by hydrous fluids. The Zhimenda basalts are geochemically similar to back-arc basin basalts in the Okinawa Trough. They were erupted related to subduction of the Longmuco–Shuanghu Paleo-Tethyan oceanic plate beneath the North Qiangtang Block. We propose that the Yushu Melange converges with the Ganzi–Litang Suture Zone to the east, rather than with the Jinshajiang Suture Zone to the southeast, and that a huge Permian trench–arc–back-arc system developed in north-central Tibet.

The lithium isotopic compositions of adakitic rocks and K-rich volcanic rocks in southern Tibet range from + 1.3‰ to + 7.5‰ and − 4.9‰ to + 3.5‰, respectively. The subduction of the Indian Plate beneath the Lhasa Terrane means that traditional lithium isotopic compositions of various reservoirs are unable to explain the aforementioned δ7Li data. Therefore, it is necessary to determine the Li isotopic compositions of the different geological endmembers underneath southern Tibet. Here, we report the lithium isotopic composition and concentration of Indian upper and lower continental crust. On the basis of whole-rock major and trace element data and Sr–Nd–Pb isotope data, leucogranites from Luozha and Longzi are considered as representative of Indian upper crust, whereas two-mica granites from Quedang and Dala and granulites and gneisses from Nyalam are considered as representative of Indian lower crust. The Li concentration of Indian upper crust varies from 23 to 45 ppm with a mean of 34 ppm, consistent with a weighted mean Li concentration for the upper crust of 35 ± 11 ppm. In contrast, the Li abundance of Indian lower crust is estimated to be 33–84 ppm with a mean of 58 ppm, much higher than the average Li concentration for the lower crust of ~ 8 ppm because of the high modal abundance of biotite and muscovite. The Li isotopic compositions (+ 0.9‰ to + 5.6‰) of Indian upper continental crust are relatively heavy compared with the average Li isotopic composition of upper continental crust. On the other hand, the Li isotopic compositions of Indian lower continental crust (− 4.4‰ to − 0.1‰) are lighter than those of Indian upper continental crust. The isotopically heavy signature of Indian upper crust is produced by high-δ7Li fluids released from the Indian lower crust slab, whereas the lighter signature of Indian lower crust is generated by the partial melting of residual Indian lower crust slab during metamorphic dehydration of Indian lower crust.

The Xiadan gold deposit from Jiaodong Peninsula contains more than 200 t of gold, and is one of the representative largest deposits within south part of the Zhaoping Fault zone. The gold orebodies consist of auriferous altered rocks that show disseminated and stockwork mineralization. Mineralization and alteration are structurally controlled by the NE- to NNE-striking Linglong detachment fault. Mineralization can be divided into three stages: (K-feldspar)–sericite–quartz–pyrite, quartz–gold–polymetallic sulfide, and quartz–carbonate, with the majority of the gold being produced during the middle stage. Based on a combination of petrography, microthermometry, and laser Raman spectroscopy, three types of fluid inclusion were identified in the vein mineral assemblages: NaCl–H2O (A-type), CO2–H2O–NaCl (AC-type), and pure CO2 (PC-type). Quartz crystals in veins that formed during the early stage contain mainly AC-type primary fluid inclusions, with rare PC-type inclusions. These fluid inclusions homogenize completely at temperatures of 253°C–408°C and have medium–low salinities (1.62–11.89 wt.% NaCl equivalent). Quartz crystals that formed during the middle stage contain all three types of fluid inclusion, and these fluid inclusions homogenize completely at temperatures of 176°C–335°C and have salinities of 0.70–14.73 wt.% NaCl equivalent. In contrast, quartz that formed during the last stage contains only A-type fluid inclusions; these inclusions have homogenization temperatures of 108°C–253°C and salinities of 1.73–11.60 wt.% NaCl equivalent. The above data indicate that the ore-forming system evolved from a CO2-rich mesothermal fluid into a CO2-poor fluid as a result of an influx of meteoric water. Fluid immiscibility is an essential prerequisite for metals precipitation in Xiadian. The characteristics of fluid inclusions, combined with H–O–S isotopes suggest that the ore-forming fluids might be of metamorphic origin. Based on the immiscibility of AC-type fluid inclusions, trapping pressures have been estimated at 88–339 MPa during ore formation, with a depth of metallogenesis of 8.8–12.6 km. The depth of erosion of study area has been calculated as about 10.3 km between 130 Ma and the present. Considering the gold mineralization occurred at around 130 Ma, the space with deep gold exploration is expectable at Xiadian.

The Sanjiang metallogenic belt includes a variety of economically important carbonate-hosted Pb-Zn deposits that share some similarities with classic Mississippi Valley-type (MVT) ore deposits but are hosted within a thrust belt rather than an orogenic foreland. This study aims to clarify the origin of mineralizing fluids responsible for this style of mineralization. Fluid inclusions trapped in ore-stage carbonate and fluorite from these deposits have salinities of ~6 to 28 wt % NaCl equiv and homogenization temperatures of 70° to 370°C that extend to much higher values than are typical of MVT deposits. The majority of ore-stage samples have fluid inclusion molar Br/Cl ratios of between seawater (1.5 × 10 −3 ) and (2.86 ± 0.04) × 10 −3 , but low-salinity fluid inclusions in late calcite have lower Br/Cl of less than (0.55 ± 0.01) × 10 −3 . In contrast, fluid inclusion molar I/Cl ratios are uniformly greater than the seawater value of ~0.8 × 10 −6 and extend from (2.1 ± 1.1) × 10 −6 to (506 ± 12) × 10 −6 . This range of Br/Cl and I/Cl values is similar to what has been reported for fluid inclusions in other MVT districts and together with the fluid salinity implies the ore-forming fluids had a dominant origin from basinal brines (e.g., sedimentary formation waters) formed by the subaerial evaporation of seawater; all the fluids were influenced by addition of organic Br and I derived from the sedimentary host rocks and some fluids were locally modified by interaction with evaporites producing low Br/Cl ratios. The fluid inclusions have 40 Ar/ 36 Ar ratios of up to 441 that are higher than the atmospheric value of 296 and typical of carbonate sedimentary rocks. The fluid inclusions have high concentrations of atmospheric 36 Ar and variable 129 Xe/ 36 Ar and 84 Kr/ 36 Ar ratios that are outside the range expected from mixing air and air-saturated water. These data are likely to reflect a complex fluid history involving acquisition of atmospheric ( 36 Ar, 84 Kr, 129 Xe) and radiogenic (e.g., 40 Ar ✼ ) noble gases trapped in sedimentary rocks and fractionation of these gases between water and hydrocarbons. The 3 He/ 4 He ratios of fluorite fluid inclusions range from a typical crustal value of 0.061 ± 0.004 to values of >0.7 Ra, indicating a minor component of mantle-derived 3 He. The fluids with the highest 3 He/ 4 He also have 4 He/ 40 Ar ✼ close to the mantle value, suggesting the 3 He could have been introduced by a volumetrically minor fluid of either magmatic or deep metamorphic origin ( 40 Ar ✼ = radiogenic 40 Ar). The new halogen and noble gas data are consistent with a model in which regional Pb-Zn mineralization formed by mixing two modified basinal brines that were transported through independent aquifers and fluid pathways to the sites of mineralization. A low-temperature brine contained organic Br, I, and H 2 S, and a high-temperature metal-rich brine (>370°C) that included a volumetrically minor magmato-metamorphic component was channeled up deeply penetrating thrust structures.

The recently discovered Zhuxi W–Cu ore deposit is located within the Taqian–Fuchun Ore Belt in the southeastern edge of the Yangtze Block, South China. Its inferred tungsten resources, based on new exploration data, are more than 280 Mt by 2016. At least three paragenetic stages of skarn formation and ore deposition have been recognized: prograde skarn stage; retrograde stage; and hydrothermal sulfide stage. Secondly, greisenization, marmorization and hornfels formation are also observed. Scheelite and chalcopyrite are the dominant metal minerals in the Zhuxi deposit and their formation was associated with the emplacement of granite stocks and porphyry dykes intruded into the surrounding Carboniferous carbonate sediments (Huanglong and Chuanshan formations) and the Neoproterozoic slate and phyllites. The scheelite was mostly precipitated during the retrograde stage, whereas the chalcopyrite was widely precipitated during the hydrothermal sulfide stage. A muscovite 40Ar/39Ar plateau age of about 150 Ma is interpreted as the time of tungsten mineralization and molybdenite Re–Os model ages ranging from 145.9 ± 2.0 Ma to 148.7 ± 2.2 Ma (for the subsequent hydrothermal sulfide stage of activity) as the time of the copper mineralization. Our new molybdenite Re–Os and muscovite 40Ar/39Ar dating results, along with previous zircon U–Pb age data, indicate that the hydrothermal activity from the retrograde stage to the last hydrothermal sulfide stage lasted up to 5 Myr, from 150.6 ± 1.5 to 145.9 ± 1 Ma, and is approximately coeval or slightly later than the emplacement of the associated granite porphyry and biotite granite. The new ages reported here confirm that the Zhuxi tungsten deposit represents one of the Mesozoic magmatic–hydrothermal mineralization events that took place in South China in a setting of lithospheric extension during the Late Jurassic (160–150 Ma). It is suggested that mantle material played a role in producing the Zhuxi W–Cu mineralization and associated magmatism.

Understanding the geological history of the Lhasa Terrane prior to the India–Asia collision (~ 55 ± 10 Ma) is essential for improved models of syn-collisional and post-collisional processes in the southern Lhasa Terrane. The Miocene (~ 18–10 Ma) adakitic magmatism with economically significant porphyry-type mineralization has been interpreted as resulting from partial melting of the Jurassic juvenile crust, but how this juvenile crust was accreted remains poorly known. For this reason, we carried out a detailed study on the volcanic rocks of the Yeba Formation (YF) with the results offering insights into the ways in which the juvenile crust may be accreted in the southern Lhasa Terrane in the Jurassic. The YF volcanic rocks are compositionally bimodal, comprising basalt/basaltic andesite and dacite/rhyolite dated at 183–174 Ma. All these rocks have an arc-like signature with enriched large ion lithophile elements (LILEs; e.g., Rb, Ba and U) and light rare earth elements (LREEs) and depleted high field strength elements (HFSEs; e.g., Nb, Ta, Ti). They also have depleted whole-rock Sr–Nd and zircon Hf isotopic compositions, pointing to significant mantle isotopic contributions. Modeling results of trace elements and isotopes are most consistent with the basalts being derived from a mantle source metasomatized by varying enrichment of subduction components. The silicic volcanic rocks show the characteristics of transitional I–S type granites, and are best interpreted as resulting from re-melting of a mixed source of juvenile amphibole-rich lower crust with reworked crustal materials resembling metagraywackes. Importantly, our results indicate northward Neo-Tethyan seafloor subduction beneath the Lhasa Terrane with the YF volcanism being caused by the initiation of back-arc rifting. The back-arc setting is a likely site for juvenile crustal accretion in the southern Lhasa Terrane.

The deep crustal continental components and architecture of the western Central Asian Orogenic Belt (CAOB) have long been a matter of debate. This article presents an integrated study of published geochronological and Hf-in-zircon isotopic data for inherited zircons from the Palaeozoic granitoid rocks and associated felsic volcanic rocks of the Chinese Altai, East Junggar, and nearby regions. The aim is to trace the age spatial distribution of deep old crustal components. Our data set comprises 463 published age data obtained by SHRIMP and LA-ICP-MS from felsic igneous rocks in these areas. Among these samples, zircon xenocrysts were observed in 69 granitic rocks and 15 felsic volcanic rocks from the Chinese Altai and 30 granitoid rocks and five felsic volcanic rocks in the East Junggar, respectively.Three major zircon xenocrysts provinces are defined based on the distribution of these inherited zircon ages, combined with Hf-in-zircon isotopes. Province I, mainly situated in the eastern part of th...

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 CO2-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 40Ar/39Ar 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), 143Nd/144Nd (0.5123–0.5127), and 207Pb/204Pb (15.601–15.628) and 208Pb/204Pb (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, SO42−, and CO2 in the rocks of the complexes, it is likely that the REEs were transported by these ligands within hydrothermal fluids, and the presence of bastnasite indicates that the REEs were precipitated as fluorocarbonates. Petrographic, fluid inclusion, and field studies of the ores indicate that bastnasite and other REE minerals formed during the final stages ( The mineralization formed from magmatic and meteoric fluids containing CO2 derived from the decarbonation of carbonatite, as indicated by C–O isotopic values of hydrothermal calcite and bastnasite (δ13C = −4.8 to −8.7 and δ18O = 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 δ18O = 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.

Recent studies argue that subduction-modified, Cu-fertilized lithosphere controls the formation of porphyry Cu deposits in orogenic belts. However, it is unclear if and how this fertilization process operates at cratonic edges, where numerous large non-arc Au-rich deposits form. Here we report data from lower crustal amphibolite and garnet amphibolite xenoliths hosted by Cenozoic stocks that are genetically related to the Beiya Au-rich porphyry deposits along the western margin of the Yangtze craton, China. These xenoliths are thought to represent cumulates or residuals of Neoproterozoic arc magmas ponding at the base of arc at the edge of the craton that subsequently underwent high-pressure metamorphism ca. 738 Ma. The amphibolite xenoliths are enriched in Cu (383–445 ppm) and Au (7–12 ppb), and a few garnet amphibolite xenoliths contain higher Au (6–16 ppb) with higher Au/Cu ratios (2 × 10 −4 to 8 × 10 −4 ) than normal continental crust. These data suggest that metal fertilization of the base of an old arc at the edge of the craton occurred in the Neoproterozoic via subduction modification, and has since been preserved. The whole-rock geochemical and zircon Hf isotopic data indicate that melting of the Neoproterozoic Cu-Au–fertilized low-crustal cumulates at 40–30 Ma provided the metal endowment for the Au-rich porphyry system at the cratonic edge. We therefore suggest that the reactivated cratonic edges, triggered by upwelling of asthenosphere, have the potential to host significant Au ore-forming systems, especially non-arc Au-rich porphyry deposits.

There is a long-standing controversy regarding the tectonic division, composition and structure of the continental crust in the Da Hinggan Mountains and adjacent areas, which are mainly part of the southeastern Central Asian Orogenic Belt (CAOB). This paper approaches these issues via neodymium isotopic mapping of Paleozoic–Mesozoic (480 to 100 Ma) granitoids. On the basis of 943 published and 8 new whole-rock Nd isotopic data, the study area can be divided into four Nd isotopic provinces (I, II, III and IV). Province I (the youngest crust, Nd model ages (TDM) = 0.8–0.2 Ga) is a remarkable region of Phanerozoic crustal growth, which may reflect a major zone for closures of the Paleo-Asian Ocean. Province II (slightly juvenile crust, TDM = 1.0–0.8 Ga), the largest Nd isotopic province in the southeastern CAOB, is considered to reflect the recycling of the initial crustal material produced during the early stage (Early Neoproterozoic) evolution of the Paleo-Asian Ocean. Province III (slightly old crust, TDM = 1.6–1.1 Ga) is characterized by ancient crustal blocks, such as the central Mongolian, Erguna, Dariganga and Hutag Uul–Xilinhot blocks, which represent micro-continents and Precambrian basements in the southeastern CAOB. Several parts of Province III are located along the northern margin of the North China Craton (NCC), which is interpreted as a destroyed cratonic margin during the Paleozoic and Mesozoic. Province IV (the oldest crust, TDM = 2.9–1.6 Ga) mainly occurs within the NCC and reflects its typical Precambrian nature. These mapping results indicate that the boundary between Provinces II and III (the northern margin of the NCC) along the Solonker–Xar Moron Fault can be regarded as the lithospheric boundary between the CAOB and NCC. Provinces I and II account for 20% and 44% of the area of the southeastern CAOB, respectively, and therefore the ratio of continental growth is 64% from the Neoproterozoic to the Mesozoic, which is typical for this part of the CAOB and distinguishes the CAOB from other Phanerozoic orogens in the world.

New major and trace elemental, Sr–Nd–Pb isotope, and zircon U–Pb geochronological and Hf–O isotope data of post-collisional potassic and ultrapotassic volcanic rocks (PVRs and UPVs, respectively) along with geochemical data of PVRs, UPVs, and Mg-rich potassic rocks (MPRs) in the literature are used to constrain their mantle source and genesis. The PVRs, UPVs, and MPRs share similar geochemical features but with some discrepancies, suggesting that they were derived from subcontinental lithospheric mantle (SCLM) with isotopic heterogeneity resulting from the varying contributions of subducted Indian lower crust into the mantle source (ca. 6–20%, ca. 8–30%, and ca. 9–30%, respectively). The zircon Hf–O isotopic compositions of these rocks can be classified into two groups, including Group I rocks with high δ18O (6.7–11.3‰), low eHf(t) (− 17.0 to − 12.0), and old Hf crustal model ages (1.87–2.19 Ga) that indicate an ancient SCLM source, and Group II rocks with δ18O values of 6.8–10.7‰, eHf(t) values of − 11.8 to − 6.3, and younger Hf crustal model ages (1.50–1.86 Ga). The negative correlation defined by δ18O and eHf(t) of Group II samples suggests a two-component mixing between mantle- and crust-derived melts, in which the latter would be the subducted Indian lower crust as indicated by the similar negative eHf(t) values between Group II samples (− 11.8 to − 6.3) and the High Himalayan gneiss (− 14.2 to + 0.3). Thus we propose two enrichment events to account for the Hf–O isotopic compositions of the PVRs and UPVs/MPRs: the first involves the enrichment of the overlying SCLM that was metasomatized by fluids derived from dehydration of the subducted Indian lower crust, and the second invokes the enrichment of the overlying SCLM metasomatized by melts of the already dehydrated different proportions of the Indian lower crust. We argue that break-off of the northwards subducted Indian Plate in the early Miocene caused the asthenospheric upwelling under the Indian plate through slab window, resulting in varying degrees of partial melting of the overlying metasomatized heterogeneous SCLM to produce the primitive magmas of the PVRs, UPVs, and MPRs in an extensional setting. These observations and interpretations imply that the Indian lower crust was subducted beneath the Lhasa terrane in the Early–Middle Miocene.

The Shimensi W–Cu–Mo deposit is one of the largest tungsten deposits in the world. Despite numerous geochemical studies conducted on ore-related granites in the district, few studies have concerned magma chambers processes. In this study, systematic in-situ major- and trace-element studies across plagioclase crystals from the ore-related Mesozoic granites as well as whole-rock Sr–Nd isotopic compositions of such granites in the Shimensi deposit were used to constrain the sources of calcium, the dynamics of the magmatic system and the metallogenic geodynamic setting. In-situ analyses of plagioclase showed no obvious positive correlations between An and FeO, while Sr was positively correlated with Ba, indicating that the magma chambers in the Shimensi deposit may have experienced chemically-closed evolution affected only by thermal mixing and/or decompression, without chemical mixing with mafic magma from the mantle. This conclusion was also supported by whole-rock Sr–Nd isotopic characteristics of high (87Sr/86Sr)i (0.71664–0.73689) and negative eNd(t) values (−9.81 to −5.07). It was found that the calcium needed for scheelite mineralization may have been predominantly provided by biotite granodiorite (BG) because of its high calcium content and large size, while ore-forming metals should mainly have been derived from the magma sources of pelites and basic volcanic rocks in the Shuangqiaoshan Group instead of the recharging of mafic magma. Moreover, change of the stress environment likely facilitated the formation of long-term stable, large-volume, highly evolved felsic magma chambers in the shallow crust, which would have been critical to the formation of the giant Shimensi W–Cu–Mo deposit.

The Miocene Sungun porphyry Cu–Mo systems, located in Azerbaijan belt, NW Iran, is associated with the high-Sr/Y magmas, which were engendered in a post-collisional setting. However, the petrogenesis of these fertile magmas and their mineralisation are still unknown. In this study, we present whole-rock major-trace elements, zircon U–Pb dating and the Lu–Hf isotopes in the ore-forming porphyries of the Sungun porphyry systems. The corresponding results showed that the samples were rich in large-ion lithophile elements and poor in high-field-strength elements; moreover, they presented both high K2O (2.4–3.5 wt%) and Sr (727–770 ppm) and low Y (11–14 ppm) contents. The zircon U–Pb age of the Sungun porphyry was ~19 Ma, with positive eHf(t) ratios (5.5–11.8) and young TDM2 ages between 322 and 705 Ma. Additionally, the Sungun high-Sr/Y porphyries contained anhydrites (CaSO4); and had high zircon Ce4+/Ce3+ ratios (33–728), relatively low zircon saturation temperatures (620–804 °C), and plagioclases with excess Al content. Overall, these evidences suggest that a water-fluxed melting of the subduction-modified juvenile lower crust might have generated a high oxygen fugacity, leading to the formation of the hydrous and S-rich Sungun fertile magmas in the NW Urumieh–Dokhtar magmatic Arc.

Ore systems are located in zones of enhanced and focused heat and fluids flux within the lithosphere. In order to target deep ore deposits under cover, a better understanding of lithospheric architecture is essential, especially in relation to magmatism and fluids. Here we attempt an integrated approach using zircon Lu Hf isotopic mapping (455 samples with 5049 zircon analyses, including 1021 new data), combined with whole-rock geochemistry and isotopes of mantle-derived mafic rocks, high-resolution seismic tomography from 325 seismic stations and new thermochemical modelling, to establish the lithosphere architecture in southeastern Tibet. The integrated data suggest lithospheric refertilisation accompanied by heat flux from the asthenosphere, and also reveal the evolutionary pathway of the volatile components. The approach adopted in our study can be used in exploration for porphyry Cu Au, orogenic-Au and rare earth element deposits in Southeastern Tibet, and illustrate the usefulness of lithosphere-architecture mapping as a useful tool for mineral exploration.