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The study of Carboniferous magmatism in northern West Junggar plays an important role in understanding the tectonic evolution of that part of the Central Asian Orogenic Belt. In this study, we present petrology, zircon U–Pb geochronology, mineral and whole-rock geochemistry, and the Sr–Nd–Hf–Pb isotope compositions of volcanic rocks from the Hamutusi area of northern West Junggar. LA–ICP–MS zircon U–Pb analysis of a representative andesite yielded an early to late Carboniferous age of 324.4 ± 6.9 Ma. The volcanic rocks are calc-alkaline, with high SiO2 (54.2–57.8 wt%), MgO (5.97–8.33 wt%), Mg# (60–69), Cr (147–448 ppm), and Ni (29.1–120 ppm) contents, and are enriched in large ion lithophile elements (LILE) and light rare earth elements (LREE), but depleted in high field strength elements (HFSE), these characteristics are similar to those of typical sanukitoids within the Setouchi volcanic belt in Japan. All samples have radiogenic initial Sr and Pb isotopic compositions, and low eNd(t) and eHf(t) values, indicating the sanukitoids were generated by partial melting of subducting sediments in which the melts interacted with the mantle. Geochemical modeling calculations indicate a proportion of 3–10% sediment melt and slab-derived fluids were mixed with the depleted mantle to produce the bulk of the Hamutusi rocks. We conclude that the studied rocks from north West Junggar record the initiation of ridge subduction related to a transition from normal subduction to subduction of young and hot oceanic lithosphere between the early and late Carboniferous.

Two new homosioflavonoids, ophiopogonanone I (1) and methylophiopogonanone C (2) were isolated from the tuberous roots of Ophiopogon japonicus. Their structures were elucidated on the basis of extensive spectroscopic analyses. The absolute configuration of compounds 1 and 2 were assigned on the basis of CD method. In addition, compounds 1–2 were tested for their cytotoxic activities against HL-60, SMMC-7721, and MCF-7 human cancer cell lines, and compound 2 showed significant cytotoxic activity against HL-60 cell line with IC50 value of 14.42 μM.

To better understand the origin of voluminous silicic rocks in a convergent continental margin, we conducted an integrated study in which we have obtained geochronological, mineralogical, and isotopic (including whole-rock Sr–Nd–Pb, in-situ zircon Hf) data of the Heri batholith in West Qinling on the NE Tibetan Plateau. The batholith is composed of metaluminous to weakly peraluminous granodiorites (235–233 Ma) and porphyritic granodiorites (230–223 Ma) with an I-type affinity. Both lithologies share similar major, trace elemental and Sr Nd isotopic compositions. Detailed elemental data demonstrate that these granodioritic rocks underwent fractional crystallization of hornblende and apatite, with plagioclase (i.e. sieve-textured plagioclase cores) accumulation to some extent. Except for porphyritic granodiorites, the Pb isotopes for other analyzed samples are characterized by high radiogenicity and uniformity ((206Pb/204Pb)t: 17.263–18.472, (206Pb/204Pb)t: 15.571–15.591, and (206Pb/204Pb)t: 38.032–38.304), together with limited variations in initial Sr ((87Sr/86Sr)t: 0.707251–0.708103) and Nd (eNd(t) = −7.1 to −6.3) isotopes with two-stage model ages (TDM2) of 1.58–1.52 Ga. These factors collectively point to a derivation from the Mesoproterozoic basement rocks at the lower crustal level, or a comprehensive mixing of different-age components that generated an average crustal residence age. The Sr Nd isotopic compositions of the porphyritic granodiorites are strikingly similar to those of granodiorites. Compared with the experimental melt compositions of amphibolites, the Heri granitoids are probably derived from an amphibolitic source under fluid-absent conditions due to the incongruent breakdown of amphibole and biotite. Based on the temporal–spatial distribution of granitic intrusions in West Qinling and the regional tectonic evolution, our interpretation is that the Heri batholith was formed during the initial collision between the North China Craton (NCC) and the South China Craton (SCC), which was accompanied by the closure of the Paleotethyan Ocean. Considering both previously published data and our new data, we propose that the Heri granitoids were mainly generated by the partial melting of lower crustal amphibolites, with minor mantle-derived melts.

The mechanism of magma generation during continental collision remains enigmatic. Appinite–granite suites commonly occur within collisional orogenic belts, providing an opportunity to monitor lithospheric evolution and the geodynamic processes involved. This paper presents geochronological, mineralogical, and geochemical data for the Eocene (~50 Ma) Pengcuolin appinite–granite suite, which is the first such suite to have been found in the southern Lhasa Terrane, southern Tibet. Two distinct populations of plagioclase are observed in the appinitic rocks: high-An plagioclases that crystallized as an early phase from H2O-saturated mafic magmas, and low-An plagioclases that formed as a late phase at pressures of ~3 kbar and ~5 kbar, as calculated from equilibrium thermobarometry using low-Al and high-Al amphiboles, respectively. The amphibole-rich appinitic rocks have low SiO2 contents and moderate values of Mg#, and are enriched in large ion lithophile elements and depleted in high field strength elements. They have homogeneous initial 87Sr/86Sr ratios of 0.705174–0.705330, eNd(t) values of 0.85 to 1.47, and zircon eHf(t) values of 3.3 to 7.9. These features suggest the appinites were derived from the melting of mantle peridotites that had been permeated by slab-derived fluids. Whole-rock geochemical data, equilibrium melting calculations, and ABS5 modeling results indicate that the primary melts of the appinitic rocks were generated from garnet-stabilized mantle, and that the melts then ascended with crystallization taking place under H2O-saturated conditions and under variable temperatures and pressures. The associated granites have a high and narrow range of SiO2 contents, and they exhibit a high-K calc-alkaline character, and low A/CNK ratios and Mg# values. These geochemical characteristics, plus their widespread distribution and depleted isotopic compositions (87Sr/86Sri = ~0.705, eNd(t) = 1.12–1.59, and zircon eHf(t) = 6.9–9.2), are comparable to those of Cenozoic granitoids elsewhere in southern Tibet and consistent with the partial melting of juvenile mafic lower-crustal materials. This appinite–granite suite not only attests to a flux of slab fluids through the lithospheric mantle during breakoff of the Neo-Tethyan slab, it also sheds light on the vertical profile of magma evolution from the deep mantle to the shallow crust. The emplacement of the appinite–granite suite was facilitated by regional faults, but the rising hydrous basaltic magmas were often trapped by the thick overlying continental crust, and those underplating magmas provided the heat and water that caused the partial melting of the continental crust, finally leading to the widespread Cenozoic felsic (and rare mafic) magmatic rocks of southern Tibet.

There is considerable controversy over the nature of (strongly) peraluminous granitoids and their relationship with coeval metaluminous granitoids. The origin of peraluminous granitoids is of great importance for an understanding of granite petrogenesis, as well as the formation and evolution of the continental crust. This study reveals the presence of contemporaneous metaluminous granitoids and muscovite-bearing peraluminous granitoids in the Guomaying composite pluton (GCP) at approximately 243–242 Ma in West Qinling in the NE Tibetan Plateau. The Middle Triassic granitoids in the GCP can be petrographically and geochemically divided into two groups. The group I samples are characterized by slightly higher K2O/Na2O ratios and are metaluminous with lower Zr-saturation temperatures (740–756 °C). In contrast, the group II samples have lower K2O/Na2O ratios and mostly strongly peraluminous compositions, with marginally higher Zr-saturation temperatures (762–778 °C). Both groups share similar trace elements and Sr–Nd–Pb–Hf isotopic compositions, pointing to middle to lower crustal origins with an amphibolitic residue. The metaluminous granitoids are interpreted as partial melting of amphibolites in the middle to lower crust beneath West Qinling, and the muscovite-bearing peraluminous granodiorites were also generated by partial melting of an amphibolitic source, with addition of a feldspar-rich component in the source. The hydrous basaltic melts derived from partial melting of a metasomatized mantle wedge source were also incorporated into the magma mush. It is inferred that disparate magma sources, entrained peritectic assemblages, and various degrees of antecryst recycling collectively exerted influence on the granitic magma chemistry of the GCP. Consequently, our data suggest that muscovite-bearing strongly peraluminous granitoids, which are widely regarded as the products of recycled metasedimentary rocks, can also originate from an amphibolite-dominated source with involvement of a feldspar-rich component.

The separation of the Indian Plate from the Australia–Antarctic Plate and its accretion to the Eurasian Plate is the key to understanding the evolutionary history and paleogeographic reconstruction of Eastern Gondwana in the Jurassic–Cretaceous. In this paper, zircon U–Pb dating indicates that the Charong Dolerites (~ 142 Ma) are newly recognized Lower Cretaceous magmatic rocks in the central Tethyan Himalaya in southern Tibet. These dolerites are characterized by moderate contents of SiO2 (49.9–56.9 wt%), high contents of MgO (4.66–9.69 wt%) and TiO2 (2.20–2.81 wt%), high Zr/Y ratios (7.5–13.1), enrichments in Rb and Th, moderately negative Nb–Ta anomalies, and no Zr–Hf anomalies. Taking into account the narrow range of whole-rock initial 87Sr/88Sr ratios (0.7068 to 0.7086), the negative values of eNd(t) (− 2.4 to − 4.1), and the geochemical makeup of the zircons, the Charong Dolerites are akin to continental basalts, indicating that the central Tethyan Himalayan area was in an extensional setting during the Early Cretaceous. Although the Charong Dolerites indicate a relatively high mantle-melting temperature (~ 1469 ± 44 °C), this is still lower than the temperature required for a mantle plume origin. In combination with the Lower Cretaceous mafic rocks in the eastern Himalaya and the coeval volcaniclastic sediments, we suggest that the Charong Dolerites were partial melts of a rising asthenospheric mantle, this process having been triggered by rifting between the Indian Plate and the Australia–Antarctic Plate. This episode of continental lithospheric extension may have led to the opening of a post-Neotethyan oceanic basin that extended between the Indian Craton and the Tethyan Himalaya during the late Early Cretaceous, a feature that is highly significant in paleogeographic reconstructions of Eastern Gondwana.

The subduction history of the Neo-Tethys is critical for understanding the early-stage tectonic evolution of the Qinghai–Tibetan Plateau. Arc volcanics, which usually record the subduction process, thus can help trace the evolution of the Neo-Tethys. In this paper, we report for the first time zircon LA-ICP-MS U-Pb ages, whole-rock major and trace element geochemistry, as well as Sr–Nd–Hf isotopic data for the volcanic rocks from the Danshiting Formation at the southern edge of the Lhasa Terrane. Two samples collected from the Danshiting Formation volcanic rocks yield zircon U-Pb ages of 97.1 ± 0.8 Ma and 90.1 ± 0.7 Ma, respectively. The volcanic rocks of the Danshiting Formation are composed dominantly of basalts and andesites characterized by depletion of high-field-strength elements, low (87Sr/86Sr)i ratios (0.7042–0.7045), high eNd(t) (+2.1 to +2.7) and high eHf(t) values (mean + 11.6). These rocks show geochemical affinity of arc volcanic rocks. The volcanic rocks of the Danshiting Formation may have formed during the northward subduction of the Neo-Tethys. This paper, combined with the previous data, briefly divide the northward subduction of the Neo-Tethys into four periods: the Jurassic (195–150 Ma), when the magmatic activity was controlled by the northward high-angle subduction of the Neo-Tethys that produced volcanics of the Yeba and Bima formations; the Late Jurassic to Early Cretaceous (150–110 Ma), when the Neo-Tethys subducted at low-angles; the Late Cretaceous (110–80 Ma), when subduction was of the Andean-type and produced volcanic rocks of the Danshiting Formation; the Paleogene (70–40 Ma), when there was transition from ocean-to-continent subduction to continent–continent collision that produced volcanic rocks of the Linzizong Group.

The Precambrian origin and evolution of the Lhasa Terrane remain unclear. Here, we present new zircon U–Pb isotopic and whole-rock geochemical data for the RenTso gabbros of the central Lhasa Terrane. These data indicate that these gabbros formed during the early Neoproterozoic (∼925 Ma) and have affinities with high-Fe–Ti basaltic rocks, given that they contain low concentrations of SiO2 (39.8–49.0 wt%) and high concentrations of FeOT (11.3–23.5 wt%), TiO2 (2.19–5.70 wt%), and V (333–1204 ppm). These gabbros also have N-MORB-like trace element features such as low (La/Sm)N ratios (0.50–0.57) and the absence of negative Nb–Ta anomalies. Combining these features with the high whole-rock eNd(t) (+5.04 to +7.55) and zircon eHf(t) (+7.8 to +13.0) values for these samples indicate that the RenTso gabbros formed by the partial melting of depleted asthenospheric mantle. The Fe–Ti enrichment in these gabbros reflects conditions of low oxygen fugacity during magma fractionation. These gabbros are spatially associated with troctolite and peridotite units, indicating that together these units form a typical ophiolitic lithological assemblage. These geochemical and field observations suggest that the study area contains a subduction-unrelated-type ophiolite that most likely represents the embryonic crust of the Mozambique Ocean following continental rifting and breakup. The results therefore indicate that the Lhasa Terrane has a Precambrian affinity with the East African orogen and occupied a different position to the Qiangtang Terrane within the Rodinia supercontinent.

The giant Pulang porphyry Cu–Au deposit in the Yidun arc, eastern Tibet, formed due to westward subduction of the Garze–Litang oceanic plate in the Late Triassic. The deposit is hosted in an intrusive complex comprising primarily coarse-grained quartz diorite and cored quartz monzonite. Here, we investigate a suite of simultaneous (216.6 ± 1.9 Ma) diorite porphyries within the complex. The diorite porphyries are geochemically similar to mafic magmatic enclaves (MME) hosted in coarse-grained quartz diorite, and both are characterized by low SiO2 (59.4–63.0 wt%) and high total alkali (Na2O + K2O = 7.0–9.2 wt%), K2O (3.5–6.4 wt%), MgO (3.2–5.5 wt%), and compatible trace element (e.g., Cr = 72–149 ppm) concentrations. They are enriched in large-ion lithophile and light rare earth elements (LILE and LREE, respectively), but depleted in high field-strength and heavy rare earth elements (HFSE and HREE, respectively), and yield variably high (La/Yb)N ratios (17–126, average 65) with weak to negligible Eu anomalies. Furthermore, they yield low (87Sr/86Sr)i ratios (0.7054–0.7067), weakly negative eNd(t) (−2.8 to −0.8) values, and variable zircon eHf(t) (−5.4 to +0.8) and δ18O (6.0‰–6.7‰) values. These geochemical features indicate that the diorite porphyry and MME formed through crustal assimilation of a magma produced during low-degree partial melting of metasomatized phlogopite-rich subcontinental lithospheric mantle. In contrast, the coarse-grained quartz diorite and quartz monzonite have relatively high concentrations of SiO2 (61.1–65.3 wt%), K2O (4.1–5.4 wt%), and total alkali (Na2O + K2O = 7.1–8.1 wt%), and low concentrations of MgO (generally

The formation of the Shiquanhe–Yunzhug–Namu Tso ophiolite melange zone (SNMZ) within the Lhasa Terrane, Tibetan Plateau, is key to understanding the Mesozoic tectonic evolution of this terrane, which remains controversial. We show that the Yunzhug ophiolite in the central segment of the SNMZ formed at ~ 150 Ma, based on U–Pb dating of zircons from a gabbroic sample in a well-developed sheeted dike complex. Geochemically, these mafic rocks are dominated by E-MORB-type compositions, along with minor amounts of rocks with P-MORB-type compositions. The samples also exhibit high eNd(t) values and lack negative Nb and Ta anomalies. Data for all the samples plot within the MORB array on a Th/Yb–Nb/Yb diagram. Therefore, these mafic rocks most likely formed in either a slow spreading oceanic setting or an embryonic ocean, and not in a back-arc basin as has been previously assumed. Taking into account the regional geology, we propose that the Yunzhug ophiolite is part of a distinct ophiolitic belt and represents material formed in an embryonic ocean within the Lhasa Terrane, which provides new insights into the Jurassic tectonic evolution of the Lhasa Terrane.

Ophiolites within the South Tianshan orogenic belt directly record the nature and tectonic evolution of the South Tianshan Ocean (STO), which is key for understanding the accretionary history of the Central Asian Orogenic Belt. Here we present petrological and Os isotopic data for the Wuwamen mantle peridotites from the South Tianshan orogenic belt, which provide new insights into the tectonic origin of this ophiolite and evolution of the STO. The lherzolites have low spinel Cr# (0.1–0.2), similar to those of fertile oceanic or continental peridotites that have undergone low degrees of melting. However, the extremely high Na2O (1.5–1.8 wt%) and Al2O3 (5.5–6.2 wt%) contents of the clinopyroxenes are atypical of oceanic peridotites, and resemble those of subcontinental peridotites. The harzburgites have more refractory compositions, suggesting higher degrees of melt extraction. Both the lherzolites and harzburgites have low initial 187Os/188Os ratios (

Continental convergent margins are commonly considered as significant sites for understanding crustal reworking and growth, but the geodynamic processes involving crustal growth remain highly debatable. Triassic intermediate–felsic intrusive rocks are widespread in the northwestern segment of the West Qinling orogenic belt on the NE Tibetan Plateau. These rocks well document the evolution of one branch of the Paleo-Tethys oceans (i.e., the A'nyemaqen Ocean) in East Asia. Here we present a comprehensive study of zircon U Pb and Lu Hf isotopic data, along with whole-rock elemental and Sr Nd isotopic data to decipher the origins of intermediate–felsic intrusions and crustal evolution of the West Qinling in the Triassic. Two episodes of magmatism were detected in this study, i.e., the early high-Mg diorite porphyry–granodiorite–granodiorite porphyry assemblage (Episode #1, ~244–230 Ma), followed by a later monzogranite–granodiorite–granite porphyry assemblage (Episode #2, ~228–203 Ma). These two episodes of magmatism are interpreted as products related to oceanic subduction and continental collision, respectively. In Episode #1, the mafic magmatic enclaves were mainly mantle-derived and were indicative of magma mixing. The high-Mg diorite porphyries were likely derived from partial melting of the mantle wedge metasomatized by sediment-derived melts, whereas the coeval granodiorites and granodiorite porphyries mainly originated from partial melting of amphibolites with significant addition of mantle-derived components. By contrast, the granodiorite porphyries in Episode #2 probably originated from the lower crust-sourced melts with insignificant mantle contribution. The contemporaneous granodiorites and monzogranites were generated by partial melting of the crustal amphibolites or metagreywackes. The proportion of positive zircon eHf(t) values decreased from Episode #1 to Episode #2, indicating a decreasing tendency of the mantle or juvenile component contribution. Our study suggests that the addition of mantle-derived magmas to the continental crust during oceanic subduction processes played an important role in crustal growth.

It is generally believed that andesite–dacite–rhyolite suites and contemporary porphyry Cu deposits are related to subduction in active continental margin settings. However, it is still unclear which tectonic events result in the generation of porphyry Cu deposits and whether asthenospheric mantle material is involved in this process. Widespread andesitic–dacitic felsic intrusions associated with porphyry Cu deposits and rarer basalts have been identified in the Late Triassic southern Yidun arc (SYA) of eastern Tibet. However, few geochronological and geochemical data are available for these basalts, thereby hampering the development of geodynamic models for this magmatic event and the formation of related porphyry Cu deposits in the region. Here we present the first geochemical and SIMS (secondary ion mass spectrometry) zircon U–Pb data of Xiaxiaoliu basalts in the SYA. The age of the Late Triassic Xiaxiaoliu basalts (216.1 ± 2.8 Ma) is consistent with the timing of emplacement of voluminous porphyritic intrusions and the formation of Cu deposits within the SYA (peaking at 215–217 Ma). The Xiaxiaoliu basalts have E-MORB-like trace element patterns that are free of negative Nb–Ta anomalies, and have high 143Nd/144Nd(t) values, suggesting they were sourced from asthenospheric mantle without any arc-type influence. These observations, combined with the fact that some Late Triassic mineralized porphyritic intrusions within the SYA have adakitic affinities, suggest that the basalts and other igneous rocks and associated porphyry Cu deposits within the SYA were produced by tearing of a westward-dipping slab, triggering the upwelling of asthenospheric mantle material during subduction of the Garze–Litang Ocean crust.

This contribution presents a new method for Re–Os isotope dating organic-rich sedimentary (ORS) rocks by thermal ionization mass spectrometry using an H 2 O 2 –HNO 3 solution as the digestion medium, rather than CrO 3 –H 2 SO 4 or inverse aqua regia . The main underlying principle of this method is that H 2 O 2 –HNO 3 digestion would preferentially liberate hydrogenous Re and Os, and minimize the dissolution of non-hydrogenous detrital Re and Os, thereby providing more accurate and precise ages. A series of tests were performed, and the experimental data demonstrate the fundamental controls on spike–sample equilibrium and that the amount of detrital Re and Os incorporated into the system are subjected to the volumetric ratio of H 2 O 2 to HNO 3 . The optimum method is a H 2 O 2 :HNO 3 ratio of 5 to complete spike–sample equilibration, and to minimize the amount of detrital Re and Os in the system. A comparison of our new method with inverse aqua regia and CrO 3 –H 2 SO 4 showed that the three techniques yield indistinguishable Re–Os results, suggesting complete spike–sample equilibrium was achieved by all of the digestion techniques. Moreover, the data show that our new technique leaches out the least amount of detrital Re and Os isotopes relative to conventional methods Thus, we propose the H 2 O 2 –HNO 3 method may increase the precision and accuracy of Re–Os depositional ages of organic-rich sedimentary systems.

Subduction of active spreading ridges most likely occurs throughout Earth's history. Interaction or collision between spreading center and trench, with the active spreading ridge downgoing and shallowly being buried in subduction zone, results in low-pressure but high-temperature near-trench magmatism in the forearc and accretionary prism setting. The Central Asian region, a complex orogenic belt created during the evolution and closure of the Paleo-Asian Ocean (PAO) at ~ 1000–300 Ma, provides an ideal place to study the subduction of PAO spreading ridges beneath ancient continental margins. It had been suggested that the low-pressure and high-temperature mafic and intermediate to felsic magmas from the Karamaili ophiolite (KO) in the NE corner of the Junggar basin (NW China) in Central Asia were likely produced by ridge subduction (Liu et al., 2007). In this paper, we combine our new geochemical data with previous results to show that the geochemical characteristics of the bulk of KO mafic rocks range from arc basalt-like to mid-ocean ridge basalt-like and ocean island basalt-like. Their trace element patterns range from depleted to enriched in highly incompatible elements, but depleted in Nb and Ta, indicating a subduction-influenced origin. The KO intermediate to felsic rocks are calc-alkaline and boninitic in composition and have trace element signatures similar to the associated mafic rocks. The low Nb/Ta ratios of some of the mafic rocks and boninitic character of some of the intermediate to felsic rocks reflect a highly depleted source, perhaps due to prior backarc magmatism. Major and trace element models indicate complex fractional crystallization histories of parental KO magmas to generate both the mafic and intermediate to felsic rocks, but in general, crystal fractionation occurred at 1000 to 1200 °C and moderate to low (0.5 kbar to 10 kbar) pressure or

The south Gangdese region is the site of subduction of the Neo-Tethys and subsequent continental collision. Compared with widespread Cretaceous and Cenozoic magmatism, Early–Middle Jurassic magmatic rocks and related deposits are rarely reported. Our work identified a >200 km long felsic rock belt associated with Cu mineralization in the south Gangdese region. We report here zircon U–Pb ages, zircon Ce4+/Ce3+ values, and mineral assemblages of two Cu mineralized intrusions within the belt. A hornblende granite and a diorite porphyry were emplaced at 177.3 Ma and 166.3 Ma, respectively. Geological occurrence and magmatic hematite–magnetite–chalcopyrite intergrowths suggest that Cu mineralization formed coeval with Jurassic intrusions. Mineralized intrusions have high zircon Ce4+/Ce3+ and EuN/EuN∗ ratios, and hematite–magnetite intergrowths, suggesting their parent magmas were highly oxidized. Hornblende is common and primary fluid inclusions are found in titanite and apatite, indicating their parent magmas were water-saturated and exsolved volatile phases at early stage of magmatic evolution. Those magma characters contribute to the formation of porphyry Cu deposits. Given that majority subduction-related porphyry Cu systems have been eroded following uplift and denudation, the well-preserved Early–Middle Jurassic Cu mineralized igneous rocks in south Gangdese are favorable prospecting targets for subduction-related porphyry Cu deposits.

The Shedong W–Mo ore district in the south–central Dayaoshan Uplift of Guangxi, southern China hosts the Baoshan and Pingtoubei deposits, both of which occur in granodioritic plutons. Zircon U–Pb dating of granodiorites and its mafic microgranular enclaves (MMEs) in the Baoshan deposit yielded ages of 439.8 ± 3.2 and 441.1 ± 2.2 Ma, respectively. Granodiorites have moderate SiO 2 (54.5–63.0 wt.%) and high Al 2 O 3 (15.4–17.8 wt.%) contents, wide variations in major element ratios, significant rare earth element fractionation, and small negative Eu anomalies. They are rich in Th, U, Zr, and Hf, and depleted in Ba, Nb, and Ti. Their initial 87Sr/86Sr, e Nd (t), and e Hf (t) values are in the range of 0.7086–0.7091, −5.2 to −6.6 and −6.3 to +1.6, respectively. Rounded or lenticular MMEs have relatively low silica and high mafic components, depletion in Eu, Sr, and Zr, and marked negative Eu anomalies. Rb/Sr and Nb/Ta ratios, and e Nd (t) and e Hf (t) values of the MMEs are higher than those of host granodiorites, indicating a different magmatic source. Zircon U–Pb dating of the unexposed granodiorite porphyry in the Pingtoubei deposit yielded an age of 440.0 ± 1.7 Ma. The granodiorite porphyries have high SiO 2 and low K 2 O, FeO T , and MgO contents, with similar trace element features to the granodiorites at the Baoshan deposit, although the former has small negative Eu anomalies. Its initial 87Sr/86Sr values range from 0.7162 to 0.7173, e Nd (t) values from −8.7 to −12.3, and e Hf (t) values from −7.8 to +1.3, indicative of a crustal source. Nd and Hf two-stage model ages of the granodiorites, MMEs, and granodiorite porphyries have a narrow range between 1.3 and 2.2 Ga. We propose that the granodiorites and MMEs at the Baoshan deposit were produced through re-melting of middle Proterozoic crust as a result of underplating of mantle-derived magmas in a transitional compression-to-extension tectonic setting. Mantle-derived magmas provided the heat and material for the formation of the granodiorites and MMEs.

Late Permian mafic flows and dikes are prominent features in and around the Western Guangxi region in southern China. Based on petrographic, geochemical and Sr-Nd isotopic data, the western Guangxi mafic rocks are geochemically akin to the Emeishan large igneous province (ELIP) high-Ti basalts, except that they possess extremely elevated Ti/Y ratios (750–2000). The Dy/Yb and Ti/Y vs. Dy/Dy ∗ covariations of the mafic rocks indicate a garnet-controlled magmatic differentiation of a mafic melt at relatively great depth. The limited e Nd(t) range from +0.41 to +1.81 also suggests minimal crustal contamination of such a melt. Geochemical modeling using TiO 2 /Yb vs. Nb/Yb and Zr/Y vs. Nb/Y projections indicate that the parental melts of the western Guangxi mafic rocks formed at a low degree (

The Shanhu orefield, located in the northeastern Guangxi province, is an important part of W-Sn polymetallic metallogeny in the Nanling region. The Shanhu W-Sn deposit is spatially associated with the Yantianling granite. LA-ICPMS zircon U-Pb dating of the Yantianling granite yields Late Cretaceous ages of 100.9 ± 2.2 Ma and 100.8 ± 2.3 Ma. Hydrothermal muscovite 40Ar/39Ar dating yields plateau ages of 102.7 ± 1.7 Ma and 100.8 ± 0.7 Ma. This date coincides well with the LA-ICPMS zircon U-Pb age of the Yantianling granite, indicating a spatial-temporal link between the W-Sn mineralization and the granitic magmatism. In combination with regional geological data, it is suggested that a Late Cretaceous mineralization event related to granitic magmatism occurred in the Nanling region, which might have resulted from regional lithospheric extension.

On the basis of their mineral chemistry, podiform chromitites are divided into high-Al (Cr# = 20–60) (Cr# = 100 ∗ Cr/(Cr + Al)) and high-Cr (Cr# = 60–80) varieties. Typically, only one type occurs in a given peridotite massif, although some ophiolites contain several massifs that can have different chromitite compositions. We report here the occurrence of both high-Cr and high-Al chromitite in a single massif in China, the Dongbo mafic-ultramafic body in the western Yarlung-Zangbo suture zone of Tibet. This massif consists mainly of mantle peridotites, with lesser pyroxenite and gabbro. The mantle peridotites are mainly composed of harzburgites and minor lherzolites; a few dike-like bodies of dunite are also present. Seven small, lenticular bodies of chromitite ores have been found in the harzburgites, with ore textures ranging from massive through disseminated to sparsely disseminated; no nodular ore has been observed. Individual chromitite pods are 1–3 m long, 0.2–2 m wide and strike NW, parallel to the main trend of the peridotites. Chromitite pods 3, 4, and 5 consist of high-Al chromitite (Cr# = 12–47), whereas pods 1 and 2 are high-Cr varieties (Cr# = 73 to 77). In addition to chromian spinel, all of the pods contain minor olivine, amphibole and serpentine. Mineral structures show that the peridotites experienced plastic deformation and partial melting. The mineralogy and geochemistry of the Dongbo peridotites suggest that they formed originally at a mid-ocean ridge (MOR), and were later modified by suprasubduction zone (SSZ) melts/fluids. We interpret the high-Al chromitites as the products of early mid-ocean ridge basalt (MORB) or arc tholeiite magmas, whereas the high-Cr varieties are thought to have been generated by later SSZ melts.

The behavior of molybdenum isotopes in magmatic–hydrothermal systems is poorly known. Late Triassic andesitic rocks from the Disuga and Lannitang areas, and contemporaneous porphyry–skarn Cu polymetallic deposits (e.g., Pulang, Xuejiping, Yaza, Hongshan, and Langdu), from the Zhongdian region, southeastern Tibetan Plateau, China, present an ideal opportunity to study Mo isotope fractionation in magmatic–hydrothermal systems. In this study, we report Mo isotopic compositions, analyzed by multi-collector–inductively coupled plasma–mass spectrometry, of ore-forming porphyries and hydrothermal chalcopyrite, pyrite, and molybdenite from the Pulang deposit, and coeval barren andesites from the Disuga and Lannitang areas. The δ98Mo values of the Pulang porphyries (−0.59‰ to −0.05‰) are lower than those of the Disuga and Lannitang andesites (−0.29‰ to −0.03‰). In the Pulang deposit, whole-rock δ98Mo values are lower (−0.59‰ to −0.05‰) than those of pyrite (+0.73‰ to +2.09‰). Chalcopyrite has lower δ98Mo values (−0.16‰ to +1.06‰), than pyrite, but similar δ98Mo values to molybdenite (−0.18‰ to +0.06‰). We infer, tentatively, that fractional crystallization was not a major control on the Mo isotopic composition of the Pulang magmatic–hydrothermal system. Heavy Mo isotopes partitioned into pyrite relative to molybdenite, and 98Mo is thought to partition into Mo6+-bearing species relative to Mo4+-bearing species. Therefore, if MoO 4 2 − was the predominant Mo species in exsolved hydrothermal fluids, then formation of pyrite from these fluids explains the high δ98Mo values of pyrite. We infer that the chalcopyrite from the Pulang deposit contains micron-scale molybdenite inclusions, which partially explains the comparable δ98Mo values of chalcopyrite and molybdenite. Pyrite has a strong influence on Mo isotope fractionation, at least in the magmatic–hydrothermal system described here.

Common understanding of pluton-related W-polymetallic mineralization is mainly based on studies in areas with exposed granitic plutons or plutons buried at shallow levels. However, there exist a large number of ore deposits that are considered to be associated with deeply hidden granitic plutons (deeper than 500 m). Their metallogenesis is not well documented due to lack of deep drilling and sampling. In this paper, we present a deeply hidden granitic pluton recently discovered by a kilometer-scale drilling project in the Xidamingshan Mountains area in western South China. The pluton, here refereed to Xidamingshan granitic pluton, underlies the Xidamingshan W-Zn-Pb-Ag-mineralized district. Petrographic examinations reveal that the hidden granite is biotite granite with partly hydrothermal alteration and that the upper part of the pluton is subjected to greisenization. Geochronological analyses indicate that the granite pluton was emplaced at the Late Cretaceous time with zircon U-Pb ages of 98.0 ± 1.0 Ma and 99.8 ± 0.9 Ma. The emplacement was subsequently followed by hydrothermal activity as indicated by muscovite 40Ar-39Ar ages of 93 ± 3 Ma and 92 ± 3 Ma. Re-Os dating of molybdenite yields an isochronal age of 95.9 ± 1.7 Ma (MSWD = 2.2). These ages indicate that the Xidamingshan mineralization is temporally related to the hidden granite. The granite is strongly peraluminous (A/CNK = 1.50 – 1.61) with high-K calc-alkaline affinity (ASI = 1.46 – 1.61) and shows enrichment in Rb, Ta, U, and K and depletion in Nb, P, and Ti. It contains muscovite and biotite but is lack of hornblende. It shows a steady correlation between P2O5 and increasing SiO2, high Rb/Sr ratios (1.33 – 3.12), and high zirconium saturation temperature (average of 767 °C). The Xidamingshan granite is thus a typical S-type granite. Geochemical signature and negative eHf(t) values (-4.9 – −12.6) indicate that the hidden granite might have been generated by melting of crustal materials of argillaceous-depleted sedimentary rocks. Granites with such geochemical characteristics are known as having W-polymetallic mineralization specialization based on comparison with other ore-forming granites in South China. Significant W-polymetallic mineralization has been found within the thick Cambrian strata overlying the hidden granite pluton. Distribution of the related deposits demonstrates a typical zoning pattern from skarn-type W deposits, through vein-type Pb-Zn deposits, to vein-type Ag deposits. Given the combined evidences of metallogenic specialization of the source rocks for granitic magmas, geochronological coupling of the magmatism and hydrothermal activity, and the hydrothermal alteration and mineralization zoning, it is suggested that there exists a hydrothermal W-Zn-Pb-Ag mineralization system driven by the emplacement of the Late Cretaceous S-type hidden granite pluton. The findings of this study provide insights into future deep drilling and related ore exploration in regions with hidden granite in South China and the world.

Subduction of the Paleo-Pacific and Mongol–Okhotsk oceanic plates is widely believed to have caused extensive Mesozoic magmatism and lithospheric deformation in East Asia. However, it remains unclear how the two tectonic domains affected NE China, and whether a boundary exists between them, because the Songnen Block in central NE China is covered by sedimentary rocks and the related mafic magmatism has been rarely discovered. Here we report a suite of Early Jurassic (ca. 175 Ma) mafic volcanic rocks (including basalt and basaltic andesite) from the Sk2 Borehole, Songliao Basin, NE China. The Sk2 mafic rocks are characterized by high Th/U, Zr/Y and Ti/Y ratios, and their geochemical signatures are consistent with formation in a back-arc extensional setting, rather than an arc setting. The rocks show depleted zircon eHf(t) and whole-rock eNd(t) values, which are comparable to mafic rocks located on the east of the Songliao Basin. This suggests that they both have a depleted mantle source, unlike the mafic rocks on the west of the Songliao Basin with relatively enriched Nd and Hf isotopes. Early–Middle Jurassic mafic rocks are distributed in the Erguna Block, >500 km to the west from the Sk2 Borehole, whereas coeval mafic rocks are widely distributed in the nearby eastern Heilongjiang and Jilin provinces. These intraplate-like mafic rocks and the Early Jurassic bimodal rocks within the Lesser Xing'an and Zhangguangcai ranges likely formed in response to lithospheric extension that was triggered by subduction of the Paleo-Pacific Plate. The Early Jurassic mafic rocks directly underlie the oldest sedimentary rocks (the Huoshiling Formation) in the Songliao Basin, which suggests that basin formation was probably initiated by lithospheric extension.

The Lhasa-Qiangtang collision prior to the Cenozoic collision of India and Asia is a key process for the early stage of tectonic history of the Tibetan Plateau; however, when and how the Lhasa-Qiangtang collision is less well known. In this paper, we present an analysis of petrological, geochemical, Sr–Nd–Hf isotopic data, and zircon LA-ICP-MS U Pb data for the volcanic rocks from the Yunzhug area, northern Lhasa. Our new data reveal an important, previously unrecognized stage of tectono-magmatic event in northern Lhasa subterrane. Zircons from the andesites and rhyolites yield concordant ages of 120.24 ± 0.79 Ma (mean square of weighted deviates (MSWD) = 0.35) and 120.1 ± 1.1 Ma (MSWD = 1.18), respectively, which are younger than the age of Jurassic intra-oceanic magmatism and older than the 112–110 Ma Lhasa-Qiangtang collision. The Yunzhug volcanic rocks are composed of andesites and A-type rhyolites of high-K affinity. The andesites originated mainly from a mixed mantle source with variable degrees of contribution of continental crust, and the rhyolites were derived mainly from melting of lower continental crust. Addition of subducted flysch or oceanic sediments resulted in the high-K affinity. Fractional crystallization of plagioclase, K-feldspar, amphibole, and minor microlitic apatite and Fe Ti oxides minerals in the shallow level is mainly responsible for variable major and trace element contents of the andesites and rhyolites. Our results show that the early Cretaceous Yunzhug volcanic rocks can represent the early stage magmatism recording the entrance of subducted continental crust into the subduction zone, agreement with processes of arc-continent collision from intra-oceanic subduction to continental collision. The presence of oceanic sediments or monazite residual in magma source under the arc-continent zone can cause LREE enrichment to exceed the continental crust, making arc magmatic compositions close to average continental values.

It is intriguing to investigate the generation of the magmatic system and the geochemical signatures that distinguish the ore-bearing ones from barren ones, especially by examining the oxygen isotopic and trace element compositions of zircon. The oxygen isotopic composition and trace element abundances of zircons from the mineralized Pulang porphyries and the coeval Disuga and Lannitang andesites of the Yidun Terrane, eastern Tibetan Plateau, have been determined by secondary ion mass spectrometry (SIMS) and laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) in this study, respectively. Analyzed zircons have relatively high but invariant δ18O values (~ 5.8‰–6.9‰) that are indicative of derivation from homogeneous mantle or mantle-derived magmas together with contribution of mature crustal materials. We propose a model for the Late Triassic magmatism in the Yidun Terrane involving magmas derived from partial melting of subduction-metasomatized mantle peridotites that subsequently experienced melting–assimilation–storage–homogenization (MASH) processes. The low calculated Ti-in-zircon temperatures (644 °C–863 °C, generally between 640 °C and 690 °C) for these zircons may be caused by the lower solidus temperature for zircon in hydrous magmas, and partly controlled by the crystallization of amphibole. Zircon grains from porphyry copper system display small negative europium anomalies (mostly Eu/Eu* > 0.5), contrasting with pronounced negative Eu anomalies in zircons (mostly Eu/Eu* magmato-hydrothermal quartz-vein Cu-Mo-W deposit > magmato-hydrothermal quartz-vein Mo-W deposit. This study suggests that zircon trace element geochemistry probably bears significant implications for elucidating the origin of the arc magmatism and guiding exploration strategies for porphyry copper deposits.

An eclogite has been recently identified within ophiolitic melange in the western segment of the Bangong Co–Nujiang suture zone, at Shemalagou in the Gaize area of central Tibet. The eclogite consists of garnet, omphacite, phengite, rutile, quartz, diopside, and amphibole. The omphacite, which has not been recognized in the suture zone until this study, occurs as rare relics within diopside grains in the eclogite. Phase equilibria modeling shows that the eclogite formed under P–T conditions of 22–28 kbar and 600–650 °C with a low geothermal gradient of ca. 8 °C/km, suggesting that it formed during the subduction of oceanic crust. The protoliths of the eclogite and coexisting garnet amphibolites have geochemical characteristics similar to those of normal mid-ocean ridge basalt (N-MORB), confirming that the eclogites formed from oceanic crust. The presence of high-pressure (HP) eclogite indicates that the ophiolitic melange in the Bangong Co–Nujiang suture zone underwent oceanic subduction and was subsequently exhumed. We conclude that this ophiolitic belt represents a newly identified HP metamorphic belt in the Tibetan Plateau, adding to the previously recognized Songduo and Longmucuo–Shuanghu eclogite belts. This discovery will result in an improved understanding of the tectonic evolution of the Bangong Co–Nujiang suture zone and the Tibetan Plateau as a whole.

Cenozoic active structures in the Tibetan Plateau are mainly regional N–S trending extensional faults and grabens, and E–W trending extensional tracks that are related to the transition from syn- to post-collision between India and Asia. E–W trending tracks are parallel to the direction of Neo-Tethyan oceanic convergence and consist of extensional volcanic–sedimentary basins and magmatic dykes in the southern Lhasa Terrane, Tibet. N–S trending tracks comprise faults and grabens, which are widely developed in Tibet. It remains unknown how and when the geodynamic transition from E–W to N–S trending tectonic tracks occurred. This study describes both E–W and N–S trending tectonic tracks identified at Dazi area of southern Lhasa Terrane, where E–W trending mafic dykes intruded a granitoid and late-stage N–S trending felsic dykes cut across E–W trending mafic dykes. Zircons from four granitoid samples yield consistent crystallization ages of ca. 60 Ma and positive e Hf (t) values (~+ 9). An altered dioritic vein, which cuts the mafic dykes, yields an age of ca. 53 Ma. These new dating results indicate that E–W trending dykes, which formed due to regional N–S extension, were emplaced between 60 and 53 Ma. In addition, two N–S trending monzonitic porphyritic dykes, which cut the mafic dykes, yield U–Pb zircon ages of ca. 17 Ma with moderate positive e Hf (t) values (+ 3 to + 9.6), as well as a NNE–SSW trending quartz monzonitic dyke, which cuts all other types of dykes, yields U–Pb ages of ca. 13 Ma. This suggests that E–W extension took place between 17 and 13 Ma. These results, in combination with existing age data for Gangdese granitoids and mafic magmatism, indicate the occurrence of two major extensional events at 60–53 Ma and 17–13 Ma. In turn, this implies that the transition from E–W to N–S trending tectonic and the onset of E–W extension occurred at ca. 17 Ma or slightly earlier. Paleocene granitoids have geochemical characteristics that are indicative of both subduction and collision. Miocene felsic dykes show adakitic affinities, which hints the transition from syn-collision to post-collision setting. Break-off of the Neo-Tethyan slab is assumed to have been responsible for the formation of E–W trending dykes and volcanic–sedimentary basins. The N–S trending felsic dykes probably formed in response to the tearing or delamination of lithosphere subducted beneath southern Tibet.

U–Pb ages and Hf isotopes of zircons in Late Triassic and Cretaceous intrusive rocks from the Zhongdian arc, SW China, are used to decipher the tectonic, magmatic, and metallogenic processes that occurred during this period. New U–Pb dating of zircons from Late Triassic porphyries yielded ages of ca. 216 Ma and eHf(t) values of −2.1 to +6.1. Combined with previous results, the data indicate that these Late Triassic rocks were most likely derived from a juvenile mafic lower-crust with minor old crust material. However, the Cretaceous granites (∼80 Ma) have lower eHf(t) values (−7.6 to −2.4) than the Late Triassic rocks, indicating that the former originated from old crust. Based on the new data and previous studies of Mesozoic magmatic activity, a plausible model for the tectono-magmatism and metallogenesis of the Zhongdian arc is proposed. The westwards subduction of the Ganzi–Litang oceanic crust began before ∼230 Ma, resulting in the formation of a juvenile lower crust beneath the Zhongdian arc due to the underplating of mafic arc magmas during ca. 230–216 Ma. At ca. 216 Ma, break-off or slab-tearing of the west-dipping Ganzi–Litang oceanic slab led to partial melting of the juvenile lower crust, which gave rise to Cu-bearing porphyries. In the Late Cretaceous, the Zhongdian arc probably underwent post-collision extension, triggering the partial melting of the old middle–upper crustal materials and producing various granites and related Mo–Cu deposits. According to this model, the crust beneath the Zhongdian arc probably has a double-layer structure, with older crust at shallow levels and juvenile crust at deeper levels.

The Yangtze Block plays a crucial role in the revelation of the Precambrian geology of the South China Block (SCB). A series of Neoproterozoic igneous rocks have been reported along the north, west and east Yangtze Block over the past two decades. In this study, gabbros and granodiorites in the south Yangtze Block are investigated with the aim of constraining the timing and tectonic background of the SCB during the Neoproterozoic. Representative samples for the gabbro and granodiorite yielded similar zircon U Pb ages of ca. 780 Ma. The gabbros have low Nb/U ratios, Nb, Ta, and light rare earth element (LREE) content, and have eNd(t) values of +2.10 to +6.15. The granodiorites exhibit enrichments in Th, U, Zr, Hf, and LREE; depletions in high field–strength elements (HFSEs, e.g., Nb, Ta and Eu); and eNd(t) values of −3.01 to −11.85. Petrogenetic analysis of the gabbros suggests that two different mantle sources (i.e., E–MORB and N–MORB) existed in the region, and the granodiorites originated from partial melting of lower continental crust with the input of mantle materials. Our data, combined with the available geological observations, show that the gabbros and granodiorites in the Ailaoshan tectonic belt were generated in an active continental margin. The SCB was an isolated continent and continuous oceanic crust subduction occurred around it during the Neoproterozoic (ca. 876–706 Ma).

A detailed comparison of the tectonic features of Central Asian Orogenic belt (CAOB) and Tethyan Tectonic domain (TTD) is of great significance to our understanding of the origin of global orogenic systems. Currently, there are many uncertainties in the general framework to fully define the tectonic properties of the CAOB and TTD. The Pb isotope data from Paleo-Asian Ocean (PAO) ophiolites in the CAOB and Tethyan ophiolites in the TTD allow us to conduct a detailed comparative study between these two global orogenic systems. Results of the study show the presence of an isotopic boundary between the different mantle domains and tectonic properties of the CAOB and TTD, with the Xinjiang region in the former representing the transition between the two systems. The distinctive 208Pb/204Pb isotope compositions of the PAO and Tethyan mantles suggest the existence of a long time-integrated lower Th/U reservoir beneath the CAOB compared to that beneath the TTD throughout the Paleozoic. Results thus suggest the distinct Pb isotope compositions of the PAO and Tethyan mantles are intimately related to the different magma–tectonic processes that formed the CAOB and TTD. Based on plate tectonic reconstruction, the Neoproterozoic to Paleozoic evolution of the accretionary margins of the CAOB mimics the modern circum-Pacific Ocean rim. In this scenario, the PAO had a low Th/U mantle isotopic signature and the subduction of PAO crust gave rise to the circum-Pacific type accretionary orogen. On the other hand, the Tethys oceans produced the high Th/U mantle isotopic signatures in an evolving collisional orogen. Significantly, the generally radiogenic and juvenile Hf isotopic signature of the CAOB is consistent with an accretionary orogenic setting for PAO whereas the relatively more unradiogenic Hf isotopic signature of TTD is consistent with a collisional orogenic setting for Tethys oceans. Thus, our study sheds some light on the PAO evolution as well as the plate tectonic reconstruction of Central Asian and Tethyan orogens.

The Dongbo peridotite massif in the western part of the Yarlung Zangbo Suture Zone (YZSZ) in southern Tibet represents a mantle thrust sheet of more than 400 km 2 , tectonically overlying a Cretaceous melange. Spinel-harzburgite with a porphyroclastic texture is the main rock type, accompanied by subordinate dunite. Olivine (Fo 90.3–91.3 ), orthopyroxene (En 87–90 ), clinopyroxene (En 49–51 Wo 46–51 Fs 0–4 ) and spinel [Mg# = 100Mg/(Mg + Fe)] = 41.1–73.1; Cr# = (100Cr/(Cr + Al) = 23.6–87.3] are the major minerals. The peridotites are characterized by “spoon-shaped”, chondrite-normalized REE patterns with (La/Yb) CN = 0.09–0.40, and (Gd/Yb) CN = 0.23–0.95. The patterns show relative uniform depletion from Lu to Nd, followed by slight enrichment from Nd to La. These rocks represent residues of mantle rocks after variable degrees of basaltic magma extraction beneath a seafloor spreading environment, followed by modification by percolating, suprasubduction-related melts. The Dongbo peridotites have variable, unradiogenic Os isotopic compositions with 187 Os/ 188 Os = 0.1235–0.1282 and rhenium-depletion ages ( T RD ) = 0.22–0.96 Ga, implying heterogeneity of Os isotopes in the mantle beneath Neotethys. A corollary to this interpretation is that the convecting upper mantle is heterogeneous in Os isotopes.

Porphyry Cu (–Mo–Au) deposits occur not only in continental margin–arc settings (subduction-related porphyry Cu deposits, such as those along the eastern Pacific Rim (EPRIM)), but also in continent–continent collisional orogenic belts (collision-related porphyry Cu deposits, such as those in southern Tibet). These Cu-mineralized porphyries, which develop in contrasting tectonic settings, are characterized by some different trace element (e.g., Th, and Y) concentrations and their ratios (e.g., Sr/Y, and La/Yb), suggesting that their source magmas probably developed by different processes. Subduction-related porphyry Cu mineralization on the EPRIM is associated with intermediate to felsic calc-alkaline magmas derived from primitive basaltic magmas that pooled beneath the lower crust and underwent melting, assimilation, storage, and homogenization (MASH), whereas K-enriched collision-related porphyry Cu mineralization was associated with underplating of subduction-modified basaltic materials beneath the lower crust (with subsequent transformation into amphibolites and eclogite amphibolites), and resulted from partial melting of the newly formed thickened lower crust. These different processes led to the collision-related porphyry Cu deposits associated with adakitic magmas enriched by the addition of melts, and the subduction-related porphyry Cu deposits associated with magmas comprising all compositions between normal arc rocks and adakitic rocks, all of which were associated with fluid-dominated enrichment process. In subduction-related Cu porphyry magmas, the oxidation state (fO2), the concentrations of chalcophile metals, and other volatiles (e.g., S and Cl), and the abundance of water were directly controlled by the composition of the primary arc basaltic magma. In contrast, the high Cu concentrations and fO2 values of collision-related Cu porphyry magmas were indirectly derived from subduction modified magmas, and the large amount of water and other volatiles in these magmas were controlled in part by partial melting of amphibolite derived from arc basalts that were underplated beneath the lower crust, and in part by the contribution from the rising potassic and ultrapotassic magmas. Both subduction- and collision-related porphyries are enriched in potassium, and were associated with crustal thickening. Their high K2O contents were primarily as a result of the inheritance of enriched mantle components and/or mixing with contemporaneous ultrapotassic magmas.

The Yuerya gold deposit in eastern Hebei Province, China, is located on the eastern margin of the North China Craton and is hosted by Mesozoic Yanshanian granitoid rocks and adjacent Mesoproterozoic Gaoyuzhuang Formation carbonates. The auriferous quartz veins in this deposit are dominated by pyrite, with subordinate sphalerite, chalcopyrite, and galena in a quartz-dominated gangue that also contains calcite, dolomite, barite, apatite, and fluorite. Gold is present as native gold and electrum, which are generally present as micron-size infillings in microfissures within pyrite and less commonly as tiny inclusions within pyrite, quartz, and tellurobismuthite. The pyrite in this deposit has high Co/Ni ratios and contains elevated concentrations of both of these elements, suggesting that the Yuerya gold deposit has a magmato-hydrothermal origin and that the ore-forming fluids that formed the deposit leached trace elements such as Co, Ni, As, and Au during passage through Archean metamorphic rocks, Mesoproterozoic carbonates, and the Yanshanian Yuerya granitoid. Pyrite in the study area has S/Se ratios and S isotopic compositions that suggest that the sulfur (and by inference the gold) within the deposit was sourced from magmato-hydrothermal fluids that were probably originally derived from Archean metamorphic rocks and Yanshanian granitoids. Tellurobismuthite in the study area is closely intergrown with gold and was the single telluride phase identified during this study. The fineness of gold associated with tellurobismuthite is greater than the fineness of gold associated with pyrite, although the fine particle size of the gold surrounded by tellurobismuthite means that the recovery of this gold is difficult, in turn meaning that the tellurobismuthite has little significance to the economics of the Yuerya gold deposit. Only trace amounts of sulfides are associated with the tellurobismuthite within the Yuerya gold deposit, suggesting that this mineral was deposited under conditions of low fS2 and/or high fTe2. In addition, the presence of tellurides within the Yuerya gold deposit reflects a genetic relationship between the deposit and magmatism. Quartz from mineralized veins in the study area has δ18O values of 11.2‰–12.9‰ and the fluids that formed these veins have δD values of − 78.3‰ to − 72.1‰. The δ34S values of pyrite within the deposit are rather restricted (2.3‰–3.5‰). These data, combined with the trace element geochemistry of sulfides within the deposit, suggest that the formation of the Yuerya gold deposit was closely related to both Archean metamorphic rocks and the Yanshanian Yuerya granitoid.

This study presents new major and trace element, plus Sr–Nd and zircon U–Pb isotope data for the Zhongcang granitic plutons, which are located to the south of the Yongzhu–Asuo ophiolite belt within the northwestern part of the central Lhasa subterrane, Tibetan Plateau. These data provide new insights into the Late Cretaceous tectonic evolution of southern Tibet. The Zhongcang plutons are dominated by granodiorites and granites that yield zircon U–Pb emplacement ages of 94–88 Ma. They can be further divided into metaluminous and peraluminous subtypes. The metaluminous rocks have adakite-like geochemical signatures, including high SiO 2 , Al 2 O 3 , and Sr concentrations, and low Yb and Y concentrations, and high Sr/Y and (La/Yb) N ratios. These rocks also have negative eNd (t) values (− 3.17 to − 0.17), variable initial 87 Sr/ 86 Sr (i) ratios (0.705927–0.707668), and high K 2 O and Th concentrations, suggesting that they were not derived from the partial melting of subducted oceanic crust in an arc setting. The Zhongcang adakitic rocks have higher MgO and Cr concentrations and Mg# values than do contemporaneous intrusive rocks derived from a region of thickened lower crust within the central Lhasa subterrane. These data suggest that the Zhongcang adakitic rocks were generated by the partial melting of a delaminated thickened lower crust within a Late Cretaceous continental setting. In comparison with the Zhongcang adakitic rocks, the peraluminous rocks have significant negative Eu and Sr anomalies and lower eNd (t) values (− 4.06 to − 6.64). This, combined with their high Mg# values, and Cr concentrations, suggests that the peraluminous units formed from primitive magmas similar to those that formed the Zhongcang adakitic rocks, but modified by contamination with ancient crustal material and by fractional crystallization of plagioclase and apatite during uprising and/or emplacement. The Zhongcang high-Mg# granitoids provide robust evidence for Late Cretaceous crustal thickening prior to India–Asia collision.

Miocene post-collisional ultrapotassic rocks in the southern and central parts of the Lhasa Terrane of southern Tibet provide an opportunity to explore the deep processes and lithospheric evolution of the Tibetan Plateau. The magmatic source of the ultrapotassic rocks is still debated. However, the source can be identified using the Re–Os isotopic system. In this paper, we provide comprehensive data on the Re–Os isotopic compositions of ultrapotassic rocks from Mibale and Maiga areas in southern Tibet, and we refine the age of the Mibale ultrapotassic rocks to 12.5 Ma. The Os isotopic data demonstrate that crustal assimilation affected the Os isotopic compositions of some ultrapotassic rocks with low Os contents, but samples with high Os contents have little or no evidence of crustal contamination. The initial 187 Os/ 188 Os ratios of the least-contaminated ultrapotassic rocks are higher than those of primitive upper mantle (PUM). The ultrapotassic rocks show a weak correlation between initial 187 Os/ 188 Os ratios and Mg# values, a negative correlation between e Nd (t) and Mg# values, and high Ni contents and FeO/MnO ratios. These observations indicate that the ultrapotassic rocks were derived from a pyroxenite-bearing lithospheric mantle. Simple calculations indicate

The Re–Os isotopic heterogeneity of mantle-derived rocks has been well documented. However, it is unclear whether and how the Os isotopic heterogeneity of a mantle source can influence Re–Os isotopic dating and source tracing of mantle-derived melts. Here we report that replicate analyses of gram aliquots of single basaltic powders (one of reference material BHVO-2 and three of the Hatu basalts from the western Junggar region, China) show large variations in both Os concentrations and isotopic ratios. More importantly, these replicate data define good apparent Re–Os isochron correlations, yielding ages significantly older than their formation ages, and display remarkable correlations between the 187 Os/ 188 Os ratio and the reciprocal of the common Os concentration (i.e., 1/ 192 Os). This indicates that the initial Os isotopic composition in a basaltic magmatic system may be heterogeneous and cannot be homogenized by pulverizing. Theoretical and mathematical deduction demonstrates that the observed apparent Re–Os isochron correlations are the result of binary mixing without complete isotopic equilibrium at the time of formation, primarily due to limited diffusional exchange of Os isotopes between refractory Os-bearing inclusions and host minerals under mantle conditions. The regressed initial Os isotopic composition may bias the true value of the mantle source. Pulsed mantle melting and magma mixing during ascent are potential processes responsible for such initial Os isotopic heterogeneity in basaltic rock systems. Thus, when using the Re–Os isotopic system to date and to trace the source of basaltic rocks or other rocks with relatively low Os concentrations, it is necessary to consider whether the initial Os isotopic composition was heterogeneous or whether it had reached complete isotopic equilibrium.

The magnitude of crustal contamination in intra-continental OIB-like basalts is commonly difficult to assess in terms of major, trace-element and Pb–Sr–Nd isotopes. However, the Re–Os isotope system is a very sensitive tracer of the crustal component during formation of basaltic rocks. Here we report new Sr–Nd–Pb–Os geochemical and isotopic data from the Cretaceous Duofutun Volcanic Rocks (DVRs) of West Qinling, central China. The DVRs exhibit low Os abundances (4.46–42.02 ppt) with Re abundances ranging from 45.58 to 812.98 ppt, variably high Re/Os (3–126), and high initial 187Os/188Os ratios (0.2112–0.6784). We propose that the degree of partial melting is responsible for the first-order control on the variation of Os concentrations. Even the least radiogenic sample still possesses a higher initial 187Os/188Os ratio than the primitive upper mantle, implying a non-negligible contribution from high Re/Os and 187Os/188Os reservoir(s). Both the crust and pyroxenite-rich mantle are reliable candidates, but the latter cannot be reconciled with the Os mass balance between pyroxenite and ambient peridotite. Hence, we contend that these rocks were contaminated by crustal materials en route to the surface. Assimilation/fractional crystallization modeling manifests the observed isotopic variations can be produced by minor assimilation of the Proterozoic mafic lower crust. In addition, the intra-continental OIB-like basalts show a relatively wider range of 187Os/188Os ratios in comparison with MORB and OIB, confirming the continental crust can have a higher concentration of radioactive Os, which is induced by time-integrated growth.

Idiopathic scoliosis is the most common pediatric spinal deformity affecting 1% to 3% of the population, and adolescent idiopathic scoliosis (AIS) accounts for approximately 80% of these cases; however, the etiology and pathogenesis of AIS are still uncertain. The current study aims to identify the relationship between G protein-coupled receptor 126 (GPR126) gene and AIS predisposition, to identify the relationship between the genotypes of the GPR126 SNPs and the clinical phenotypes of AIS. We conducted a case-control study and genotyped twenty SNPs of GPR126 gene including ten exonic SNPs and ten intronic polymorphisms in 352 Chinese sporadic AIS patients and 149 healthy controls. We provided evidence for strong association of three intronic SNPs of the GPR126 gene with AIS susceptibility: rs6570507 A > G (p =0 .0035, OR = 1.729), rs7774095 A > C (p = 0.0078, OR = 1.687), and rs7755109 A > G (p = 0.0078, OR = 1.687). However, we did not identify any significant association between ten exonic SNPs of GPR126 and AIS. Linkage disequilibrium analysis indicated that rs7774095 A > C and rs7755109 A > G could be parsed into one block. The association between the intronic haplotype and AIS was further confirmed in an independent population with 110 AIS individuals and 130 healthy controls (p = 0.046, OR = 1.680). Furthermore, molecular mechanisms underlying intronic SNP regulation of GPR126 gene were studied. Although intronic SNPs associated with AIS didn't influence GPR126 mRNA alternative splicing, there was a strong association of rs7755109 A > G with decreased GPR126 mRNA level and protein levels. Our findings indicate that genetic variants of GPR126 gene are associated with AIS susceptibility in Chinese populations. The genetic association of GPR126 gene and AIS might provide valuable insights into the pathogenesis of adolescent idiopathic scoliosis.

Ultrapotassic lavas are widespread throughout southern Tibet and are generally thought to have formed from magmas generated by partial melting of an enriched mantle source that was metasomatized during earlier subduction events. Here, we report new geochemical and Sr–Nd–Pb–Os isotope data for Miocene ultrapotassic rocks within the Sailipu area of the western Lhasa terrane, southern Tibet. The Sailipu ultrapotassic rocks are enriched in the large ion lithophile elements relative to the high field strength elements, and have extremely radiogenic Sr (87Sr/86Sr(i) = 0.714480–0.727323), Pb (206Pb/204Pb = 18.414–18.787, 207Pb/204Pb = 15.693–15.749, 208Pb/204Pb = 39.439–39.765), and Os isotopic signatures (187Os/188Os(i) = 0.1095–0.37454), and unradiogenic Nd (eNd(t) = − 11.5 to − 15.2) isotopic compositions. These geochemical and isotopic characteristics, coupled with high K2O (> 5 wt.%) and MgO (5.20–13.70 wt.%) concentrations, Mg# values of 68–76, high Rb/Sr (0.13–0.95) and low Ba/Rb (3.33–12.3) ratios, and the relatively low Os contents and radiogenic Os isotopic compositions of the Sailipu ultrapotassic rocks, do not support any significant crustal contamination. Instead, we consider these rocks to be analogous to the Cenozoic ultrapotassic rocks from Italy and the Balkans, suggesting that they were produced by interaction between melts derived from phlogopite-rich clinopyroxene veins and surrounding peridotitic mantle material. The Sailipu ultrapotassic rocks can be divided into type-1 and type-2 suites based on differences in major and trace element concentrations, and isotopic compositions. Type-1 ultrapotassic rocks are relatively enriched in the heavy rare earth elements, most likely as a result of interaction between melts derived from phlogopite-rich clinopyroxene veins and the surrounding spinel-bearing peridotite material, whereas the type-2 rocks are enriched in rare earth elements and have high (Gd/Yb)N values (8.3–12.2), both of which are indicative of interaction between melts derived from phlogopite-rich clinopyroxene veins and surrounding garnet-bearing peridotite material that also contained carbonates. Although both the existing convective removal and oblique subduction models can explain some of the geological observations associated with the formation of the Tibetan Plateau, we suggest that the former more accurately explains the spatial and temporal distributions of ultrapotassic rocks and other Cenozoic lavas in this area and the associated topographic uplift recorded in southern Tibet.

Narigongma is a poorly studied Mo-rich (similar to 0.06 wt.%) post-collisional porphyry Cu deposit located in southern Qinghai Province, Tibet, 400 km northwest of the Yulong porphyry Cu-Mo-Au belt. The Narigongma deposit has a similar age (43-40 Ma) to porphyry deposits in the Yulong belt, but different ore assemblages. The Narigongma deposit is associated with Eocene granodiorite and granite intrusions that were emplaced into a Permian volcanic-sedimentary rock sequence. An similar to 43.3 Ma biotite granite stock (P1 porphyry) is the earliest Eocene intrusion, and this was itself intruded by a number of smaller, similar to 43.6 Ma fine-grained granite porphyry stocks (P2 porphyry) and several post-ore quartz diorite porphyry dikes (similar to 41.7 Ma). The main Cu-Mo mineralization at Narigongma is associated with the P1 porphyry. Hydrothermal alteration surrounding the deposits is generally characterized by concentric zones that range from an inner potassic zone outward to phyllic and argillic alteration zones, and an outer propylitic zone. Hypogene mineralization at Narigongrna was characterized by early-stage precipitation of molybdenite during potassic alteration and late-stage deposition of chalcopyrite during phyllic alteration. Deposition of both the Mo and Cu mineralization stages was caused by decreasing temperature. A high degree of crystallization of the P1 porphyry occurred prior to fluid saturation that produced Mo enrichment in the residual melt due to the incompatible behavior of Mo. However, compatible Cu was sequestered by the crystallizing phases and resulted in the generation of a high-Mo/Cu magmatic-hydrothermal fluid and the final Mo +/- Cu mineralization assemblage. Zircon epsilon(Hf)(t) values of +4.1 to +7.9 are indicative of magma derivation from a depleted source. These isotopic data, coupled with other geochemical characteristics of the Narigongma porphyry, such as high SiO2 and K2O contents, low MgO contents and compatible element abundances, and highly fractionated rare earth element patterns, indicate a mixing model for the origin of the porphyry bodies. Generation of the post-collisional ore-forming porphyries occurred in two stages: (1) partial melting of metasomatized phlogopite-bearing lithospheric mantle that generated potassic to ultra-potassic mafic melts, and (2) underplating of such melts beneath thickened juvenile lower crust, which triggered partial melting of the lower crust to produce the ore-forming, high-K adakitic magma. (C) 2013 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

Ore-bearing porphyritic rocks are widely distributed in the Zhongdian arc in the southern part of the Yidun arc, eastern Tibet. New U–Pb zircon dates, and previous results, show that the porphyritic rocks formed mainly between 221 and 211 Ma, with a peak at 217–215 Ma. These Late Triassic porphyritic rocks and associated volcanic rocks are primarily calc-alkaline igneous rocks, some of which have geochemical affinities with adakite, such as high SiO2 (≥ 56 wt.%), Al2O3 (≥ 14 wt.%), and Sr, and low Y and heavy rare earth element contents. However, moderate Sr/Y and La/Yb ratios of these rocks compared with typical adakites characterize them as being transitional between adakites and normal arc rocks. Those rocks that do not have adakitic affinities are typical normal arc volcanic rocks. The porphyritic and associated volcanic rocks occur in the eastern and western parts of the Zhongdian arc, and both have the same geochemical characteristics and ages. The new dates, geochemical data, and Sr–Nd isotopic ratios, combined with previous data on the Zhongdian arc (particularly the Xiaxiaoliu basalt that has enriched mid-ocean ridge basalt characteristics), suggest that these rocks are probably related to slab break-off or slab-tearing of the westward subducting Garze–Litang oceanic crust in the Late Triassic. The enriched mantle wedge metasomatized by subducted fluids and sediments was heated by ascending asthenosphere and underwent partial melting. These magmas then probably interacted with underplated mafic material and experienced a melting–assimilation–storage–homogenization process (MASH) in the lower crust and/or with slab-derived melts, resulting in formation of the porphyritic rocks and associated porphyry deposits in the Late Triassic Zhongdian arc.

article i nfo Sulfide globules in mid-ocean ridge basalts (MORBs) from the ultra-slow spreading Southwest Indian Ridge (SWIR) are present in olivine crystals and in the matrix glass, indicating S-saturated fractionation during mag- matic evolution. Most of the sulfides were in equilibrium with the magmas based on the Ni contents of the sul- fides. The major element trends of MORBs from Zone C (48-51°E) of the SWIR define two distinct liquid lines of descent (LLD), including one which is composed of MORBs depleted in HREE. The MORBs have variable PGE con- centrations with Pd contents ranging from 0.056 to 1.572 ppb. They are PGE-depleted relative to Ni and Cu with high Cu/Pd ratios (55,000-1,785,000). Quantitative modeling using Pd vs. Ni correlations yields relatively low amounts of segregated sulfides for both groups assuming complete equilibration between the sulfides and the melt. However, the correlation of calculated sulfur contents with MgO suggests much higher amounts of segre- gated sulfides, indicating that the segregated sulfides are incompletely equilibrated with the magma. There are no obvious correlations between PGE concentrations and spreading rates for MORBs globally. MORBs from the SWIR show slowly decreasing PGE contents during magmatic evolution but exhibit higher sulfide seg- regation rates compared to MORBs from faster-spreading ridges, largely due to the poor equilibration between the segregated sulfides and the magma. Such incomplete equilibration could result from thicker lithosphere and an absence of steady magma chambers and conduits beneath ultra-slow spreading ridges.

The Sangri Group volcanic rocks are distributed along the southern margin of the Lhasa Terrane on the northern side of the Indus-Yarlung Zangbo suture zone. This Group consists of the Mamuxia and Bima formations and has long been considered to be Late Jurassic to Early Cretaceous in age. In this paper, we report for the first time zircon LA-ICPMS U-Pb ages, whole-rock major and trace element geochemistry, as well as Sr-Nd isotope data of the Bima Formation volcanic rocks in the Sangri County, Tibet. Two samples collected from the Bima Formation volcanic rocks yield zircon U-Pb ages of 195 ± 3 Ma and 189 ± 3 Ma, respectively. These data suggest that the Bima Formation volcanic rocks formed during the Early Jurassic rather than the Late Jurassic-Early Cretaceous as previously reported. The volcanic rocks of the Bima Formation are dominantly composed of basalt and andesite that are enriched in LILEs and LREEs, but depleted in HFSEs, showing typical characteristics of arc volcanic rocks. They also show positive e Nd (t) (+ 4.09 to + 7.02) values and low initial 87 Sr/ 86 Sr (0.7032 to 0.7050) ratios, similar to the MORB of the Indus-Yarlung Zangbo ophiolites, indicating that the Bima Formation volcanic rocks were derived from a depleted mantle wedge. The magmas subsequently experienced juvenile crust contamination and fractional crystallization during ascent. Geochemical features of magmas of the Bima Formation volcanic rocks are interpreted to be generated by the northward subduction of Neo-Tethys beneath the southern Lhasa Terrane as early as ~ 195 Ma. Coeval with a large volume of Late Triassic-Early Jurassic felsic intrusions within the Gangdese arc, the Gangdese magmatic arc is interpreted to be initiated at a juvenile continental margin during the Late Triassic-Early Jurassic, although a possible intra-oceanic arc setting cannot be excluded.

It has been suggested that the Dupal isotopic anomaly in the mantle can be traced in the Paleozoic ophiolites from the Neo- and Paleo-Tethyan Ocean (275–350 Ma). The Karamaili ophiolite (KO) and Dalabute ophiolite (DO) in the eastern and western corners, respectively, of the Junggar basin in NW China represent remnants of the relatively older (> 350 Ma) Paleo-Asian Ocean (PAO) crust. Thus, these ophiolites can provide additional constraints on the long-term composition and evolution of the Paleozoic suboceanic mantle. We present new major-trace element and Sr, Nd and high-precision Pb isotope data for the basalts, gabbros and a plagioclase separate from the KO and DO. Our results indicate that the PAO crust indeed has a Dupal-like isotopic signature. In detail, all samples have relatively low e Nd( t ) and high 208 Pb/ 204 Pb ( t ) for given 206 Pb/ 204 Pb ( t ) ratios (i.e., positive Δ8/4 values), similar to the Dupal isotopic characteristics of Indian Ocean mid-ocean ridge basalts (MORB). The trace element signature of DO mafic rocks is similar to that of normal- and enriched-MORB whereas that of the KO is transitional between MORB and arc basalt. Therefore, the DO mantle domain reflects the PAO asthenosphere and the KO domain additionally shows the influence of the subduction process. Geochemical modeling using Th/Nd as well as Nd and Pb isotopic ratios indicates that up to 2% subduction component had been added to a depleted Indian MORB-type mantle to produce the bulk of KO rocks. The subduction component in the KO rocks consisted of variable proportions of ≤ 1% partial melt of unradiogenic sediment similar to modern Izu–Bonin trench sediment and hydrous fluid dehydrated from the subducted altered oceanic crust. The Devonian asthenospheric mantle beneath the southern PAO is isotopically heterogeneous, but lends support to the idea that the Dupal isotopic anomaly existed prior to the opening of the Indian Ocean. Finally, plate tectonic reconstruction indicates that the anomaly was present in the Neo- and Paleo-Tethyan oceans in the southern hemisphere and in the southern part of PAO in the northern hemisphere during the late Paleozoic.

Highly magnesian lavas or picrites have the potential to preserve important information about the origin and thermochemical state of the mantle source(s) of large igneous provinces. We have conducted a comprehensive study of highly siderophile element (HSE) concentrations in picrites from the ca. 260 Ma Emeishan large igneous province. We show that HSE abundances in the Emeishan picrites are greater than those in mid-ocean ridge basalts (MORBs) and parental melts of Hawaiian picrites, but are similar to those in komatiites. The picrites have two types of C1-normalized HSE patterns: (a) type 1, as represented by the Muli picrites is similar to that of the primitive upper mantle; (b) type 2, as represented by the Dali picrites resembles East Greenland and Iceland picrites. Pt/Ir and Pd/Ir ratios in the type 2 picrites are higher than those in type 1 picrites. The primary melt compositions of the studied samples have been estimated by back-addition of equilibrium olivine. The calculated HSE abundances of the parental liquids of the Dali and Muli picrites are higher than those of the parental melts to Hawaiian picrites. Along with previously published isotopic data, our study provides further evidence for chemical heterogeneity of the Emeishan mantle plume.

The Dongshangen polymetallic ore district is located in east section of the Eastern Kunlun Mountains, the south eastern margin of the Qaidam Basin, and is one of the most important polymetallic mining regions. However, there is a relatively lower research degree on the district, especially lack of thermochronology data. Using zircon and apatite fission track thermochronology, this article reveals the tectonic activities experienced in Dongshangen polymetallic ore district. It is shown that the 6 age groups of geological thermal events, i.e., 197 Ma, 182–170 Ma, 160–110 Ma, 110–80 Ma, 80–23 Ma and 23–0 Ma. Combining with the geological characteristics, we consider that the 6 age groups belong to 6 periods of tectonic activities in the Dongshangen ore district. The first age group of 197 Ma mainly resulted from the South Kunlun fault strike-slip and the Qiangtang block collided with the Kunlun block; the second age group of 182–170 Ma was related to the Songpan-Ganzi-Bayan Har Basin closure; the third age group of 160–110 Ma was bound up with the left-lateral strike-slip took place in the North Kunlun fault, and the squeezing and collaging activities of both the Qiangtang block and the Lhasa block toward the Eurasian plate; the event during the 110–80 Ma responded to northward subduction of the Neo-Tethys Ocean and strong strike-slip in the Altyn Tagh fault zone; the Late Cretaceous to Miocene (80–23 Ma) was affected by the northward napping of the Central Kunlun terrane and the northward subduction of Neo-Tethys Ocean continued; from 23 Ma to present, the collision of the Indian plate toward the Eurasian plate occurred, leading to the Qinghai-Tibet Plateau uplifting as a whole. Synthesizing the geological characteristics and the tectonothermal events, we discriminate 4 metallogenic periods of 197 Ma, 182–170 Ma, 155–112 Ma and 109–88 Ma in the district, better reflecting the characteristics of multi-stage metallogenic events.