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The North China Craton (NCC), which underwent multiple subduction and lithospheric destruction during the Mesozoic, is well known for hosting some of the world-class gold deposits. In many cases, Mesozoic mafic dykes are associated with the gold deposits, although there has been no systematic studies aimed to integrate the characteristics of these dykes in different regions of the NCC. Here we investigate diabase and lamprophyre dyke suites in the Xiaoqinling region along the southern margin of the NCC, and compile the published geochronological, geochemical and isotopic data for regional mafic dykes and gold deposits from the major gold belts including Jiaodong, Xiaoqinling and central NCC. Zircon U-Pb data show the mafic dykes in Xiaoqinling were emplaced in two episodes at 219–227 Ma and 121–137 Ma, and their εHf(t) values (ranging from −2.1 to 3.8 and −13.6 to 1.6 respectively) suggest increasing input of lithospheric materials in the Early Cretaceous dykes. The compiled geochemical data on the mafic dykes from different regions in the NCC show that the magmatic evolution involved olivine and clinopyroxene fractional crystallization with limited crustal contamination and subduction-related fluid metasomatism. The geochemical and isotopic signature suggests multiple sources for the parent magma of the mafic dykes ranging from convective asthenospheric mantle to ancient lithospheric mantle, with the magma source characterized by enriched mantle (EM2 or EM2+ EM1), and that signatures might be potential for gold mineralization. Further, most dykes are coeval and cospatial with gold deposits in the NCC. The geochronological data show that small amount of both Mesozoic dykes and gold deposits formed in Triassic whereas the peak formed in Cretaceous following slab roll back of the Pacific plate subducting from the east during 145–110 Ma. We envisage that the tectonic extension associated with Pacific slab subduction contributed to the magmatism and gold mineralization in the NCC. [ABSTRACT FROM AUTHOR]

The Shihu quartz vein‐type gold deposit in the central North China Craton occurs within Neoarchean TTG (tonalite‐trondhjemite‐granodiorite) gneisses and shows spatial relationship with quartz diorite porphyry. The occurrence of the ore body is controlled by the N‐S fracture. Primary mineral assemblage of the ore body is composed of quartz, calcite, and base‐metal sulphides, including pyrite, galena, sphalerite, chalcopyrite, and pyrrhotite. Eight pyrite samples from veins of the main mineralization stage yield an isochron age of 129 ± 3 Ma (MSWD = 1.6), coinciding with the major Early Cretaceous magmatic event, and associated lithospheric thinning recognized in the NCC. The (87Sr/86Sr)i values of the pyrite (0.7102 ± 0.0006) are lower than the continental crust mean value (0.719) and higher than that of the mantle initial ratio (0.707), suggesting mixed crust–mantle source for the metallogenic components. Three types of hydrothermal pyrite from the early to major ore‐forming stages were identified in the quartz vein, including Py(I) as disseminated euhedral grains, Py (II) as dense bulks, and Py (III) as intergrowth with base‐metal sulphides. Electron microprobe analysis of the pyrite grains indicates a trend from S‐deficient to S‐enriched and from Fe‐enriched to Fe‐deficient stages, suggesting an increase in sulphur fugacity and reducing conditions. The arsenic in pyrite shows decrease against increasing Au during Stages II and III, implying that As is not the only trigger of gold precipitation, but electrochemical‐geochemical barrier played a major role in the formation of the ore. The Co and Ni concentrations, as well as Co/Ni ratios in pyrite, are relatively high, which provide an additional clue to the link with the regional magmatic event. Combined with the textural features, we propose a wider potential for gold exploration in this region, linking the mineralization with a major transitional tectonic regime. [ABSTRACT FROM AUTHOR]

The Shihu quartz vein‐type gold deposit, the largest gold deposit in the central North China Craton, occurs within wall rocks of Neoarchean TTG (tonalite–trondhjemite–granodiorite) gneiss and shows a close relationship with the early Cretaceous Mapeng granitoid pluton and various intermediate–mafic dykes. The occurrence, morphology, composition, and precipitation mechanism of the Au–Ag minerals are short of research, which is the purpose of this study. The primary mineral assemblage of orebody contains quartz, calcite, and base‐metal sulphides including pyrite, galena, sphalerite, chalcopyrite, and minor pyrrhotite and enargite. The Au–Ag minerals can be classified into three distinct types, namely, (a) quartz‐hosted, (b) pyrite‐hosted, and (c) base‐metal sulphidehosted, corresponding to formation sequence. Electron microprobe analysis indicates that these Au–Ag minerals show fineness (=Au/[Au + Ag] × 1,000) ranging from 976 to 366 with an average of 667 and are rich in Bi, Te, and Hg while deficient of Cu, As, and Se. Bismuth and tellurium in the Au–Ag minerals show a linear relationship with Au, whereas in the coexisted sulphides are almost below detection limits. We suggest that Bi and Te fundamentally influenced the transportation, enrichment, and precipitation of gold as scavengers to concentrate and deposit gold at the location with an "appropriate distance" from magma. Phase analyses of native bismuth and Bi–Te minerals included in pyrite, reported for the first time in Shihu Gold deposit, imply that the gold precipitation witnessed the ore‐forming fluid evolution with log fTe2 decreasing from approximately −11 to approximately −15 and log fS2 increasing from approximately −13 to more than −11. Mineralogical mapping with the fineness of Au–Ag minerals (fineness contours) suggest that the ore‐forming fluids came from the deep earth beneath the north of the mining area with excellent gold potential, which has been verified by later drilling. [ABSTRACT FROM AUTHOR]

Mesozoic magmatism and lithospheric destruction in East China exerted significant control on gold metallogeny. Here, we investigate the mineralogy, geochemistry, geochronology, and isotopic systematics of the Dongyang gold deposit in southeast China to constrain its origin and geodynamics. This is a newly discovered epithermal gold deposit along the Circum–Pacific metallogenic belt and is characterized by intense silicification and sericitization. The C–H–O isotope data suggest deep magmatic sources of the ores and indicate that the ore‐forming fluids comprised a mixture of magmatic water and meteoric water. The S–Pb values of the pyrite indicate magmatic origin for the sulfur, and deposit was derived mostly from crustal sources, mixed with mantle materials. The Rb–Sr dating of the pyrite from the ore deposit shows an age of 164.2 ± 9.9 Ma, whereas the zircon U–Pb SHRIMP ages of the rhyolite porphyry is 160.9 ± 0.5 Ma, suggesting that the timing of mineralization is close to that of the crystallization of the dykes. In conjunction with previous studies on similar deposits, we suggest that the gold mineralization was the response of continental lithospheric thinning in southeast China triggered by the subduction of the Palaeo‐Pacific Ocean Plate. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The Diaoquan Ag-Cu deposit formed at about 130 Ma, during the peak stage of the destruction of NCC. • The metallogenic components were sourced from both mantle and crust. • The inner and deeper domains of the intrusions have good potential for future prospecting. Abstract The North China Craton (NCC) has been the focus of investigations on metallogeny in relation to craton destruction. The Diaoquan Ag-Cu polymetallic skarn mineralization is one of the large Ag deposits in central NCC. Here we present new mineralogical, geochronological and geochemical data from this deposit with the objective to gain an insight into the magmatic hydrothermal processes in relation to decratonization. The timing of polymetallic mineralization in this deposit is constrained as ca. 130 Ma by phlogopite Ar-Ar and molybdenite Re-Os dating. The physico-chemical conditions of the magmatic evolution estimated from amphibole, biotite, magnetite-ilmenite mineral thermobarometer indicate that the monzonite and porphyritic granite magma developed in a magma chamber at a palaeoburial depth of 2–3.3 km, and was subsequently emplaced at 1–2 km palaeodepth. The oxygen fugacity conditions were relatively high (>ΔNNO + 1.6 buffer) in the early stage and rapidly dropped (<ΔFMQ buffer). The major and trace element features suggest magma mixing as a possible mechanism that generated the different intrusions. Sr-Nd-Pb and zircon Hf isotope data indicate that lower crust is the major source of the magma and that part of metallogenic elements might have been sourced from mantle-derived components. We constructed the magmatic hydrothermal system as follows: (1) mafic magma formed by the partial melting of thinned mantle lithosphere; (2) the mafic magma underplating resulted in the partial melting of the lower crust, and generated granitic magma; (3) mixing of the mafic and felsic magmas generated the intermediate magma; (4) ore-forming fluids from the magma chamber migrated into the contact zone through fractures, resulting in Ag-Cu mineralization by skarnization; and (5) Mo-bearing fluid separated from the granite magma deposited the molybdenite in the inner contact zone. [ABSTRACT FROM AUTHOR]

The widespread tectonic and magmatic events in Southeast China during the Mesozoic were accompanied by large‐scale metallogenesis. Here, we investigate the petrology, geochemistry, and zircon U–Pb age of the porphyry dykes in relation to the gold mineralization at Dongyang deposit in the Fujian Province. The geochemical data show silica‐rich and Mg‐ and Ca‐poor A‐type granite affinity for the dykes. The rocks have high concentrations of Light Rare Earth Elements (LREE) and Large Ion Lithophile Elements (LILE) and relatively low contents of Heavy Rare Earth Elements (HREE) and High Field Strength Element (HFSE). They display (La/Yb)N and (La/Sm)N values in the range of 5.7 to 31.4 and 6.0 to 8.3, respectively, with negative anomalies of Ba, Nb, Ta, Sr, Zr, Eu, and Ti and positive Ce anomaly. The source magma for the dykes was derived from a mixture of partially melted Al‐rich crustal material, with an input of mantle components. We present sensitive high‐resolution ion microprobe zircon U–Pb data from the dykes, which show emplacement ages in the range of 158 to 162 Ma, coinciding with the onset of the Yanshanian magmatism in Southeast China. Integrating the data obtained from studies on geology, geochronology and petro‐geochemistry, we suggest that the dykes played role in controlling the gold mineralization, and the magmatism and gold mineralization are the response of continental lithosphere thinning in Southeast China triggered by the subduction of the ancient Pacific Ocean Plate. [ABSTRACT FROM AUTHOR]

The Niujuan breccia-type silver deposit forms part of the North Hebei metallogenic belt along the northern margin of the North China Craton. The Hercynian Baiyingou coarse-grained granite and the Yanshanian Er’daogou fine-grained granite are the major Mesozoic intrusions exposed in this region. Here we investigate the salient characteristics of the mineralization and evaluate its genesis through zircon U-Pb and fluorite Sm-Nd age data, and Pb, S, O, H, He and Ar isotope data. The orebodies of the Niujuan silver deposit are hosted in breccias, which contain angular fragments of the Baiyingou and Er’daogou granitoids. The δ 34 S values of pyrite from the silver mineralized veins range from 2.4‰ to 5.3‰. The 206 Pb/ 204 Pb, 207 Pb/ 204 Pb and 208 Pb/ 204 Pb ratios of the sulfide minerals show ranges of 16.837–16.932, 15.420–15.501 and 37.599–37.950, respectively. The 3 He/ 4 He and 40 Ar/ 36 Ar ratios of the fluids trapped in pyrite are 0.921–4.81Ra and 299.34–303.84, respectively. The δ 18 O and δ 18 D w values of the ore-forming fluids range from 0.6‰ to −4.15‰ and from −119.4‰ to −98.7‰, respectively. Our isotopic data suggest that the ore-forming fluids were originally derived from the subvolcanic plutons and evolved into a mixture of magmatic and meteoric water during the main hydrothermal stage. The ore-forming materials were primarily derived from the lower crust with limited incorporation of mantle materials. The emplacement time of the Er’daogou granite is constrained by LA-ICP-MS zircon U-Pb geochronology at 145.5 ± 2.1 Ma. Five fluorite samples from the last hydrothermal stage yielded a Sm-Nd isochron age of 139.2 ± 3.8 Ma, indicating the upper age limit for the silver mineralization. These ages correlate with the formation of the Niujuan deposit in an extensional setting associated with the closure of the Mongol-Okhotsk Ocean and the subduction of the Paleo-Pacific oceanic plate beneath the North China Craton. [ABSTRACT FROM AUTHOR]

The Karakoram Block in North Pakistan formed during the late Permian-Triassic on the southern margin of Asian Plate with a topography characterized by glaciated high mountains. Several rivers and streams draining from these mountain peaks carry detritus with precious and base metals. However, the primary source deposits and their ore genesis remain unknown due to the rugged glaciated topography and inaccessibility for prospecting and in situ sampling. Here, we present a multi-parametric analytical approach including major and trace element characteristics, thermoelectric analysis, EPMA elemental mapping, XRD analysis, and sulfur and lead isotopic studies on the detrital auriferous pyrite from Shimshal Valley placer gold deposits in the Karakoram Block of the north Pakistan to gain insights into the ore genesis, provenance and current erosion or denudation rate of the source primary deposits found in the hinterlands of the Shimshal Valley. The pyrite with varying forms such as {100} + {111} + {210} followed by {210} + {111} and {100} + {210}, which are highly enriched in gold (up to 1700 ppm) as revealed through EPMA analysis. The low to moderate temperature estimated for their formation (100 to 360 °C), pyrite geochemical characteristics, geochemical discrimination diagrams (Fe/S-As, Fe + S-As, As-Co-Ni) and elements contents (Au, Ag, Cu) of the placer gold grains, as well as the high (58.2 %) and low (41.8 %) thermoelectric coefficients of N-type and P-type, suggest that the auriferous pyrite belong to the epithermal type of magmatic-hydrothermal systems. The XnP value (average −48.7 %), γ value (average 62.8 %) in conjunction with the n(S)/n(Fe) values of 1.97–2.11 of pyrite indicate that the placer gold deposits are derived from the middle-upper part of the ore body. The high Mo/Ni (average 5.4) and Co/Ni (average 2.7) ratio combined with detrital zircon U Pb geochronology, zircon fertility indicators such as Eu/Eu*, Ce/Nd, (Ce/Nd)/Y, Dy/Yb, (Eu/Eu*)/Y, texture and REE patterns correlate the ore mineralization with the Hunza Plutonic Unit emplaced on the catchment of the valley. The narrow variations in δ34S values, ranging from −5.3 to 3.8 ‰ with an average of −4.7 ‰, suggest that sulfur has a homogeneous magmatic source. The Pb isotopes values range 18.487 to 18.692, 15.713 to 15.745, and 38.964 to 39.416 for 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb, respectively. Our results suggest that metals for ore-forming fluid involved considerable contribution of crustal-derived materials. [Display omitted] • The studied placer gold deposits are sourced from epithermal type of deposits. • Proximal source with probable mineralization beneath the current level of erosion • Gold is found in pyrite as micro to nano inclusions as Au0 instead of Au+1. • Source deposits are associated with 109 MA plutons of Hunza Plutonic Unit. • Orogenic belts and crustal derived ore forming fluids are suggested. [ABSTRACT FROM AUTHOR]

Located in the eastern section of the Central Asian Orogenic Belt, the Jiawula Ag-Pb-Zn deposit is classified as a volcanic to subvolcanic related vein-type ore deposit. New U-Pb zircon geochronology, whole-rock geochemistry, mineral chemistry, and Sr-Nd isotope data are presented for the intrusions in the Jiawula deposit in order to evaluate the timing, petrogenetic type of the granitoid rocks, origin and evolution of magmatism, geodynamics, and to establish its relationship with lead-zinc mineralization. Zircon SHRIMP U-Pb analyses yield weighted mean ages of 150.1 ± 1.8 Ma for quartz porphyry, 148.8 ± 2.2 Ma for syenite porphyry, and 145.3 ± 1.9 Ma for monzonite porphyry, indicating a Late Jurassic (Yanshanian) magmatic event. An earlier magmatic event (Indosinian) occurred during the Late Permian to Early Triassic from ca. 254 Ma to ca. 247 Ma and is represented by granodiorite (254 ± 2 Ma), dacite porphyry (252.9 ± 4.8 Ma), and diorite porphyry (278 ± 4.1 Ma). Both the Indosinian and Yanshanian igneous rocks are classified as I-type granitoids. The late Jurassic intrusions are highly fractionated and characterized by negative anomalies of Eu, Sr, P, and Ti. The hypabyssal intrusions have initial 87 Sr/ 86 Sr values between 0.70458 and 0.70522, and ε Nd (t) values of −3.4 to −0.2, indicating relatively older crust in Jiawula among more juvenile crust in this area. Magma generation in Jiawula is linked to juvenile lower crustal and slightly enriched mantle sources. The ∼250 Ma magmatic episode in Jiawula might be related to the subduction of the Mongol-Okhotsk oceanic plate towards the south beneath the Erguna massif. The ∼150 Ma magmatic event occurred after the closure of the Mongol-Okhotsk Ocean followed by the change in subduction direction of the Paleo-Pacific plate. Varying temperature, stronger fractionation and higher oxygen fugacity related to the magmatic-hydrothermal transition caused Pb-Zn mineralization. [ABSTRACT FROM AUTHOR]

The Early Cretaceous gold deposits of the Jiaodong Peninsula, eastern China, define China’s largest gold province with an overall endowment estimated more than 3000 t Au. The Wang’ershan gold deposit at the northern margin of the Jiaolai Basin in Jiaodong Peninsula of eastern China is located in the central-southern segment of the Wang’ershan fault zone. The major Mesozoic intrusions exposed in this region are the Linglong granite and the Guojialing granodiorite to the northeast of the deposit. Both these intrusions show high-K and alkaline signature. The Linglong granite displays peraluminous feature whereas the Guojialing granodiorite is metaluminous. Zircon U–Pb dating of the Linglong granite yields 206 Pb/ 238 U weighted mean age of 149.0 ± 1.3 Ma. The muscovite from the alteration zones associated with mineralization in the Linglong granite yields a plateau age of 130.35 ± 0.96 Ma, representing the initial phase of the hydrothermal activity. The δ 34 S values of pyrite from the gold mineralized veins range from 6‰ to 8.3‰ with the mean value of 7.66‰. The 3 He/ 4 He ratios of pyrite are in the range 1.58–2.71 Ra with a mean value at 2.168 Ra. The 40 Ar/ 36 Ar ratios show variation from 1220.3 to 1625.7 with an average of 1483.8. The δ 18 O values of the mineralizing fluids show a range of −2.13‰ to 7.5‰, with an average of 2.4‰. The δ 18 D w values are in the range of −97.5‰ to −61.4‰, with a mean at −82.6‰. Detailed elemental and isotopic data suggest that the hydrothermal fluids in early stage were mainly magmatic and derived from the Guojialing granodiorite, and the ore-forming fluids in the main ore-forming stages evolved into a mixture of magmatic and meteoric water. The ore-forming materials were primarily derived from crust, with minor input of mantle components. The ore-forming fluids might be related to the subduction of the paleo-Pacific slab beneath the North China Craton and the associated asthenosphere upwelling and consequent lithospheric thinning. [ABSTRACT FROM AUTHOR]

The Han-Xing region is located in the south Taihang Mountains (TM) in the central part of the North China Craton, and is an important iron producing area. The iron deposits in this region are of skarn type, related to an Early Cretaceous high-Mg diorite complex, including gabbro diorite, hornblende diorite, diorite, diorite porphyrite, and monzonite. In this study we report the detailed mineral chemistry of the high-Mg diorites and skarn rocks. The olivine in the gabbro diorite shows chemical composition similar to that in mantle peridotite xenoliths. Clinopyroxene in the gabbro diorite is dominantly augite, with only minor diopside, whereas the clinopyroxenes in the diorite and monzonite are diopside. Amphiboles in the high-Mg diorites show compositional range from magnesiohornblende to magnesiohastingsite, with minor pargasite and tschermakite. Most plagioclase in the high-Mg diorite is andesine and oligoclase. The magnesio-biotite in gabbro diorites shows chemical characteristics of re-equilibrated primary biotites and those in calc-alkaline rocks. In the diorite and diorite porphyrite, plagioclase shows complex chemical zoning. Clinopyroxene and garnet in skarn rocks show varying FeO contents, the former containing low FeO (< 9 wt.%) and occurring as the major skarn mineral in large-scale iron deposits, and the latter within small-scale iron deposits with high FeO (mostly > 25 wt.%) content. We computed the pressure, temperature, oxygen fugacity and water contents based on the mineral chemistry of amphibole and biotite. Based on the results, the magma crystallization can be divided into two stages, one within the deep magma chamber, forming clinopyroxene, amphibole and plagioclase phenocrysts; the other after emplacement, forming the rim of phenocrysts and matrix minerals. The magma during the early stage shows high temperature (~ 900 °C–950 °C), pressure (~ 300 MPa–500 MPa), relatively high logfO 2 (NNO–NNO + 2), and H 2 O content in melt (4%–8%). During the late stage, the magma temperature dropped to about 750 °C, and pressure came down to less than 100 MPa, with the logfO 2 rising to NNO + 1–NNO + 2. The zoning of amphibole and plagioclase records the process of magma mixing and crystallization, with injection of mafic magma into the felsic magma chamber. The relatively high logfO 2 and H 2 O content inhibited partitioning of iron into mafic minerals and favored concentration of Fe in the melt. Iron ore precipitation occurred when the magma was emplaced at shallow level, and was principally controlled by the chemical composition of carbonate wall rocks. The high logfO 2 , Fe 3 + rich ore-forming fluid generated andradite and clinopyroxene when it reacted with limestone and dolomitic limestone respectively. [ABSTRACT FROM AUTHOR]

The Qiubudong silver deposit is a breccia-type silver deposit in the Fuping ore cluster region within the Taihang Mountain region of the central North China Craton (NCC). The cylindrical breccia pipe occurs at the conjunction of a NE trending fracture and a NW trending fracture and along the latter a number of quartz porphyry and felsite dikes are emplaced. The breccia clasts include quartz porphyry, leptite, and felsites, cemented mainly by felsic magmatic and hydrothermal components. The ore formation process can be divided into five stages: magnetite–quartz stage (I), biotite–quartz stage (II), quartz–pyrite stage (III), quartz-polymetallic sulfide stage (IV), and quartz–carbonate stage (V). Hydrothermal alteration is characterized by pyritization, sericitization, silicification, carbonatization, potash feldspathization, epidotization and chloritization with a systematic zoning from the ore body to the margin with transitional contact boundaries. We present S, Pb, He, and Ar isotope compositions of the ore minerals and evaluate the source of the ore-forming materials and fluids. The δ34S values of the pyrite range from 0.5‰ to 3.4‰, with an average of 1.6‰, consistent with a mantle input. The Pb isotope compositions from the sulfide minerals range from 15.799 to 16.049 for 206Pb/204Pb, 15.143 to 15.241 for 207Pb/204Pb, and 36.999 to 37.590 for 208Pb/204Pb, suggesting a lower crustal origin. Helium isotopic compositions of the fluid inclusions trapped in pyrite vary from 0.45Ra to 1.65Ra with an average of 0.98Ra (Ra is the 3He/4He ratio of air equal to 1.4×10−6), tending to crustal contribution with calculated mantle helium proportions ranging between 5% and 20% (average at 12%). Six pyrite samples from the silver deposit yield a Rb–Sr isochron age of 102.04±0.61Ma, whereas crystallization of the quartz porphyry dike is dated by zircon U–Pb LA-ICP-MS chronology at 107.95±0.87Ma. These ages suggest a close link between the silver mineralization and magmatism that generated the quartz porphyry. Combined with previous age data, we infer that the magmatism and metallogenesis in the central NCC took place during 140–100Ma with a duration of 40Ma, accompanied by mantle upwelling and lithospheric thinning. [ABSTRACT FROM AUTHOR]

Abstract: The Beiyingxigou quartz vein and alteration type Pb–Zn–Ag deposit forms part of the metallogenic region southwest of the Mapeng batholith in the Central North China Craton. The quartz vein-type polymetallic deposit is associated with intermediate-felsic intrusives emplaced with Mesoarchean metamorphic basement. The mineralization is dominantly controlled by N–S and NW–SE trending faults. We identify four distinct stages of mineralization associated with the hydrothermal activity: pyrite phyllic stage, quartz–pyrite stage, quartz–polymetallic sulfide stage, and quartz–carbonate stage. Among these, the first two stages and the quartz–polymetallic sulfide stage represent the early and main metallogenic stages, respectively. Here we present results from integrated stable isotope studies (S, Pb, He–Ar and H–O) to deduce the possible sources of the mineralizing fluids and metals. The δ34S values recorded in the sulfide minerals of the early and main metallogenic stages show ranges of +0.4‰ to +2.2‰, and −11.4‰ to −6.8‰, respectively. The data illustrate two distinct pulses of hydrothermal fluids with δ34S mean values of 1.1‰ and −8.7‰. The S isotopes of pyrite and galena, sphalerite from the early and main metallogenic stages suggest a mixed source from the Mesozoic magmatism and the Precambrian basement. We infer that the slow cooling magma at the main metallogenic stage led to a larger interaction with the country rocks and resultant contamination, as compared to the early–middle metallogenic stage. The lead isotopic composition of pyrite, galena and sphalerite from the early to main stages shows restricted ranges with 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios of 15.720–16.275, 15.068–15.140 and 38.688–41.316, respectively. The data are all characterized by lower crustal nature, suggesting the contribution of Pb from both the Mesozoic intrusions and the basement rocks in the region. The 3He/4He and 40Ar/36Ar ratios of fluid inclusions from the Beiyinxigou Pb–Zn–Ag deposit show a range of 0.01–0.23 Ra and 270.2–298.1, respectively. The 4He and 40Ar concentrations vary from 26.6 to 340.6 (10−7 cm3 STP/g) and 165.6 to 357.9 (10−7 cm3 STP/g), respectively, suggesting dominantly crustal contribution. The δ18OQ values of quartz and the δ18Dw values show ranges of 10.9‰ to 13.6‰ and −85.2‰ to −57.8‰, respectively. The calculated δ18OW values of the mineralizing fluids show a range of 3.7‰ to 7.5‰. Our data suggest that the hydrothermal fluids were a mixture of both magmatic and meteoric water. The results presented in this study link the Beiyinxigou Pb–Zn–Ag deposit to metallogeny associated with Mesozoic magmatism in the North China Craton. [Copyright &y& Elsevier]

Abstract: Magmatism and associated metallogeny provide important constraints on geodynamic processes. The Hengshan terrain of northern Taihang Mountains located within the central North China Craton is well-known for several Mesozoic gold deposits. Here we investigate the Yixingzhai quartz vein-hosted gold deposit associated with the Sunzhuang quartz monzodiorite intrusive complex. We present U–Pb data on zircon grains from the monzodiorite which constrain the timing of emplacement of the pluton as ca.134Ma, coeval with the formation of Yixingzhai quartz vein gold deposit (at ca. 131Ma). The magmatism and metallogenesis during early Cretaceous in the Hengshan terrain are part of a major regional magmatic and metallogenic event in the Taihang Mountains and elsewhere in the North China Craton at ca. 130Ma ago. We characterize the zircon grains from the Sunzhuang quartz monzodiorite through morphology, internal structures and chemistry, and also present data from analyses of the chemistry (Co and Ni), and S–Pb–D–O isotopes of the minerals from the Yixingzhai gold deposit and Sunzhuang quartz monzodiorite. Our results reveal a lower crustal signature with mantle input for the source magma of the Sunzhuang Pluton. The magma was enriched in water and alkalis and shows a wide range of crystallization temperature (850–550°C, and mainly 650 to 700°C) under high oxygen fugacity. The ore minerals and the mineralizing fluids in the Yixingzhai gold deposit were derived from magma generated in the lower crust with additional input of mantle components. Our study links the gold metallogenesis with magmatism in the Hengshan terrain. Based on the new results reported in this study, and in conjunction with our interpretation of the ultra-broadband high-precision magnetotelluric sounding profile from the region, we suggest that the lithosphere beneath the Hengshan terrain was strongly thinned and decoupled between the crust and mantle in the early Cretaceous, and that the partly destructed lithosphere was largely preserved through the Cenozoic to present. The metallogenesis in the Hengshan terrain was closely related to the lithosphere thinning and crust–mantle decoupling in the North China Craton. [Copyright &y& Elsevier]

The Trans-North China Orogen (TNCO), a Paleoproterozoic suture that amalgamates the Western and Eastern Blocks of the North China Craton (NCC), witnessed extensive magmatism and metallogeny during Mesozoic, associated with intraplate tectonics and differential destruction of the cratonic lithosphere. Here we investigate a suite of porphyry dykes surrounding the Mapeng batholith in the Fuping Complex within the TNCO in relation to the Mesozoic gold and molybdenum mineralization. The major element chemistry of these dykes show a range of SiO 2 (57.92 to 69.47 wt.%), Na 2 O (3.20 to 4.77 wt.%), K 2 O (3.12 to 4.60 wt.%) and MgO (0.51 to 3.67 wt.%), together with high concentration of LREE and LILE, and relatively low contents of HREE and HFSE. The rocks display (La/Yb) N = 13.53–48.11, negative Nb, Ta, Th, U and Zr anomalies, and distinctly positive Ba, K and Sm anomalies. The mineralogy and geochemistry of the porphyry dykes indicate the rocks to be high-K calc-alkaline, and I-type, with adakitic features similar to those of the adjacent Mapeng batholith. The source magma for these rocks was derived from a mixture of reworked ancient continent crust and juvenile mantle materials. The zircon U–Pb data from these rocks show ages in the range of 124 to 129 Ma, broadly coinciding with the emplacement age of the Mapeng intrusion. The inherited zircons of ca. 2.5, 2.0 and 1.8 Ga in the dykes represent capture from the basement rocks during melting. The zircon Lu–Hf isotopic compositions show negative ε Hf ( t ) values varying from − 27.8 to − 11.3, with Hf depleted model ages ( t DM ) ranging from 1228 Ma to 1918 Ma and Hf crustal model ages ( t DM C ) of 1905 Ma to 2938 Ma, suggesting that the Mesozoic magmatism and associated metallogeny involved substantial recycling of ancient basement rocks of the NCC. We present an integrated model to evaluate the genesis of the porphyry systems and their relation to mineralization. We envisage that these dykes probably acted as stoppers (impermeable barriers) that prevented the leakage and run-off of the ore-bearing fluids, and played a key role in concentrating the gold and molybdenum mineralization. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zircon U-Pb ages of 101–148 Ma reflecting prolonged hydrothermal alteration. • Three groups of hydrothermal zircons are recognized from decratonic gold deposits. • Ore-forming fluid of decratonic gold deposits is relatively oxidized than those of orogenic and porphyry gold deposits. Decratonic gold deposits constitute the most important type of gold endowment in the North China Craton (NCC), although the nature and evolution of ore-related fluids in these deposits remain controversial. Here we investigate geochemistry of hydrothermal zircon grains from the Dahu gold deposit in the Xiaoqinling region in the southern margin of the NCC. We also compile the published information on trace elements in hydrothermal zircon from deposits in the other major gold districts of the NCC. The zircon U-Pb data show ages in the range of 101–148 Ma reflecting prolonged hydrothermal alteration that occurred within an extensional tectonic setting. Based on the trace elements, three distinct groups of hydrothermal zircons are recognized. Group 1 shows low La contents (<1 ppm), high Ce/Ce* (>10), and steep positive LREE patterns ((Sm/La) N > 20); Group 2 possesses high La contents (<10 ppm), low Ce/Ce* (<10), and weak positive LREE patterns ((Sm/La) N < 20); Group 3 displays ultra-high La contents (>10 ppm), low Ce/Ce* (<10), and flat LREE patterns ((Sm/La) N < 20). This classification is also applicable to orogenic and porphyry gold deposits. Group 1 grains initially crystallized from magma and underwent subsequent modification by post-magmatic fluids, whereas Group 2 and Group 3 directly crystallized and regrew from zirconium-saturated aqueous fluids. The La-enriched signature in hydrothermal zircons may mainly originate from undetected REE-bearing phases within zircon that formed during the hydrothermal alteration events. The fluid flow has a significant effect on the redox state of gold metallogenic system. The hydrothermal zircons from decratonic gold deposits display higher Ce/Ce* ratios (1–258) and Ce/Nd ratios (0.7–32.2) than those from orogenic and porphyry gold deposits, indicating that the zircon grains formed from a relatively oxidized fluid. [ABSTRACT FROM AUTHOR]

Abstract: The Beiminghe (BMH) iron ore in the southern part of the Taihang Mountain (TM), Hebei province, is one of the largest skarn iron deposits in China. Here we report phlogopite 40Ar–39Ar and zircon U–Pb age data, as well as sulfur, lead, and He–Ar isotope geochemistry of pyrite from the ores and skarnitized rocks in the deposit in an attempt to constrain the timing and mechanism of formation of the mineralization. The phlogopite 40Ar–39Ar and LA-ICP-MS zircon U–Pb data show markedly consistent ages constraining the timing of ore formation as 136–137Ma. The presence of several inherited zircons with late Archean or Paleoproterozoic ages indicates the participation of the basement rocks during the ore-forming process. The δ34S values of pyrite from the ores range from 12.2 to 16.5‰, with 206Pb/204Pb=17.84–18.79, 207Pb/204Pb=15.46–15.62, and 208Pb/204Pb=37.93–39.75, suggesting that continental crust is the major contributor. This is further confirmed by the He–Ar isotope data (3He/4He=0.0648–0.1886 Ra, mean 0.1237Ra; 40Ar/36Ar=311.7–22909.4; and 40Ar⁎/4He=0.036–0.421). The Mesozoic magmatism and metallogeny in the BMH correlate well with the peak event of lithospheric thinning and destruction of the North China Craton during this process, the early Precambrian lower crustal rocks in the region were re-melted through underplating of mantle magmas, leading to the formation of the Beiminghe monzodioritic pluton. Minor mantle input occurred during the evolution of the monzodiorite magma, which scavenged the ore-forming materials from the lower crust. Interaction of the magmas and fluids with the surrounding rocks resulted in the formation of the Beiminghe skarn iron deposits. The magmatism and metallogeny in the Taihang Mountain are signatures of the extensive craton destruction and lithospheric thinning in the eastern part of the North China Craton during Mesozoic, probably associated with Pacific slab subduction. [Copyright &y& Elsevier]

• The majority of mafic-intermediate dykes formed at 1.84–1.80 Ga. • Multiple magma sources for the 1.84–1.80 Ga dykes. • The tectonic setting dominated by craton-scale post-collisional extension for the dykes. • Correlation with adjacent continental fragments in the Columbia supercontinent. Dyke swarms formed in extensional settings and are important proxies to track mantle source characteristics as well as continent and supercontinent break-up. The late Paleoproterozoic mafic-intermediate dykes in the Xiaoqinling region, southern margin of the North China Craton (NCC), provide a window to investigate the late Paleoproterozoic magma sources and tectonic evolution. Although many studies have been conducted on this region, the timing of late Paleoproterozoic extension and tectonic setting remain debated. Here we present results from LA-ICP-MS zircon U-Pb geochronology, Lu-Hf isotopic analyses and geochemistry of these dykes, together with an evaluation of the published geochronological and geochemical data for the regional dyke activity. The zircon U-Pb data show emplacement ages of 1751–1841 Ma for the dykes and compiled age data indicate widespread late Paleoproterozoic dyke emplacement during 1.85–1.75 Ga, with the majority of formed at 1.84–1.80 Ga. The geochemical characteristics, along with zircon εHf(t) values (showing two distinct ranges: 0.7–7.4 and −5.1–0), indicate multiple magma sources for the 1.84–1.80 Ga dykes from asthenosphere and depleted subcontinental lithosphere sources followed by interaction and mixing with continental crust. Geochemically, the dykes are enriched in Ba, K and P and depleted in Nb, Ta and Sr. The geological and geochemical features of these dykes are consistent with their formation within a post-collisional extension setting. We also evaluate the significance of these dykes in terms of paleogeographic correlations within the Columbia supercontinent through correlations with the North China Craton, Indian Shield and West Australia Craton. [ABSTRACT FROM AUTHOR]

• Silver occurs as argentite, pyrargyrite and invisible silver in tetrahedrite. • The ore-forming fluids were mainly of magmatic origin. • Mixing of hydrocarbon and ore-forming fluids resulted in the precipitation of Ag. The recently discovered Erdaokan Ag-Pb-Zn deposit is located in the Duobaoshan gold-copper metallogenic belt in the eastern part of the Central Asian Orogenic Belt. The ore-bodies occur mainly as veins hosted in the breccia. Three stages of mineralization, including early magnetite-quartz-pyrite, middle silver-sulfide-bitumen-quartz and late carbonate stages, were recognized. Here we report results from electron microprobe analysis (EPMA), S-Pb-H-O isotopes and fluid inclusions studies to gain insights into the salient characteristics of the ore mineralization and mechanism of silver precipitation. The silver occurs mainly as argentite, pyrargyrite and invisible silver in the tetrahedrite grains, in which Ag, Fe and As isomorphically substituted Cu, Zn and Sb, respectively. The homogenization temperatures of fluid inclusions in the early, middle and late stage mineralisation range from 96 to 179 °C, 78 to 178 °C, and 98 to 191 °C, respectively. The fluid salinities vary from 0.35 to 5.54 wt.%NaCl equiv. The δ34S values of the pyrite and galena show a range from −0.97‰ to +9.31‰. 206Pb/204Pb vary from 18.0125 to 18.1864, 207Pb/204Pb, from 15.561 to 15.081, and 208Pb/204Pb, from 38.0445 to 37.6979, with a mean of 18.0298, 15.5125 and 37.7281 respectively. The δD and δ18O water values of the quartz from the ore body range from −119.1‰ to −109.7‰ and −4.64‰ to 1.98‰, respectively. Based on these results, we argue that the ore-forming fluids were derived from a magmatic source, with fluid mixing as the dominant mechanism for silver precipitation, involving hydrocarbon fluid interaction as inferred from the presence of bitumen in the ore. [ABSTRACT FROM AUTHOR]

The Hewan granite porphyry is a newly discovered, highly evolved Au deposit in north China. Two types magmatic zircon are found in the porphyry. Type I is CL-dark and only occurs in the core of some zircons. Type II is CL-bright and mantles Type I zircon or occurs as individual grains. The two Types are close in age, i.e. 138.0 ± 2.2 Ma for Type I and 135.9 ± 2.1 Ma for Type II. Type I zircon is enriched in Y, U, Th, Nb, Ta, P, REE, while Type II zircon is relatively depleted in these elements, which reflects a reverse in the magma evolution. Whole-rock geochemistry and the presence of xenocrystic zircons (2522 ± 18 Ma), combined with ε Hf (t) (−20.2 to −22.3) and δ18O (5.3 to 6.6 ‰) for Type I zircons, suggests that the Hewan granite porphyry was mainly derived from the melting of the surrounding older, country rock gneiss. The higher ε Hf (t) (−16.5 to −19.4) and lower δ18O (5.0 to 6.0‰) of Type II zircon indicates that Type II zircon formed during infiltration of a later fluid. This later fluid also had a higher oxygen fugacity (Ce/Ce* Z = 248 to 3663) and a higher H 2 O activity. We propose that the Hewan granite porphyry originated from the shallow melting of regional gneisses due to heat from underplating mafic magmas related to a subduction event. Type I zircons, which formed during this event where later mantled or totally replaced by Type II zircon due to an influx of Cl-, S-, and Au-bearing fluids from these crystallizing underplating mafic magmas. The high F and pH in this shallow magma promoted decoupling of AuCl− in the upwelling fluids, which allowed for the deposition of elemental Au. • Proposed potential genesis of the Hewan granite porphyry. • Based on changes in zircon composition, we propose the genesis of Hewan granite porphyry and potential mechanism for Au enrichment. • Give insight into finding Au deposits in high-silica granites. [ABSTRACT FROM AUTHOR]

Abstract: Voluminous tonalite–trondhjemite–granodiorite (TTG) magmas were emplaced in the Huai’an Complex of North China Craton (NCC) during the Neoarchean. Here we present the geochemical characteristics of these rocks and identify low-Al (LAl) and high-Al (HAl) types of trondhjemites within the TTG suite. The LAl group displays high silica (SiO2 =77–80wt.%), and low Al2O3 contents (11.06–11.89wt.%), a strongly peraluminous (A/CNK=1.16 and 1.19) composition and enrichment in HREE (LaN/YbN =4 and 5, GdN/YbN =0.35 and 0.9). Their low Rb (13 and 28ppm), Th (0.3 and 7.0ppm), relatively high Na2O/K2O values (3.6 and 4.1) and MgO (0.63 and 0.68wt.%) with moderately high Mg# (36 and 53), suggest crystallization from a primitive source. The HAl group is characterized by relatively low SiO2 (67.22–71.57wt.%) and high Al2O3 contents (16.35–16.41wt.%) with trace element contents and distribution patterns closely comparable to those of Archean high-Al TTGs. Our geochemical data do not favor a direct genetic link between the LAl and HAl trondhjemite groups. The zircon U–Pb data reveal that the LAl and HAl groups represent coeval intrusions at ca. 2.55–2.5Ga. In situ analysis of Hf isotopes in the zircons (εHf=+5.6 to +10, and TDM =2462–2595Ma), together with the geochemical features of the low-Al trondhjemites suggest that they were generated under relatively low pressure (<8kbar), through low degree partial melting of a newly accreted amphibolitic crust. Taking into consideration the contemporaneous (2.55–2.50Ga) high-Al TTGs widely exposed in the Huai’an Complex, we suggest that the low-Al trondhjemites were formed by intraplating of mantle-derived magmas, and the coeval high-Al TTGs were produced by partial melting of a thickened lower crust, triggered by underplating. Our study attests to a major episode of Neoarchean crustal growth in the NCC, and remelting induced by underplating and intraplating of mantle-derived magmas. [Copyright &y& Elsevier]