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The North China Craton (NCC) hosts some of the world-class gold deposits on the globe, which can be classified into distinct types as the “Jiaodong type”, explosive breccia type and skarn type. The “Jiaodong type” gold deposits were formed at ca. 120–130 Ma both in the margins and interior of the NCC. Two explosive breccia gold deposits formed at ac. 180 Ma and 120 Ma and are located in the southern margin and the interior of the NCC. Important skarn gold deposits of ca. 128 Ma formed within the interior of the NCC. Although the formation and distribution of these gold deposits are temporally and spatially heterogeneous, they are commonly related with the lithospheric destruction of the NCC. The interplay of several factors such as basement architecture, inhomogeneous decratonization, crust-mantle interaction, mantle dynamics, magmatic characteristics, high heat flow and massive flux of deep-derived ore-forming fluids operated in generating the gold endowment. All the three types of gold systems are closely related with granitoid plutons and different types of dykes, the magmas for which were sourced from the lower crust near the Moho discontinuity and involved the mixing and mingling of felsic and mafic magmas. The ore forming fluids display prominent magmatic signature and were largely derived from deep domains, with probable input from the asthenosphere mantle. The heterogeneous distribution of the giant gold systems in the NCC was geodynamically controlled by the destruction of the craton. The regions at the confluence of two or three Precambrian micro-continental-blocks are generally characterized by thinned lithosphere and high heat flow, constituting the potential sites of giant gold deposits. The mantle beneath these regions shows EM2 characteristics implying the involvement of subducted oceanic components. The magmatic intrusions associated with the gold systems crystallized under high oxygen fugacity conditions and were rich in volatiles. [ABSTRACT FROM AUTHOR]

Jiaodong peninsula, located at the southeastern margin of the North China Craton, is well known for its rich endowment of super-large gold deposits. This region is also characterized by hundreds of intermediate – mafic dykes that cluster into several dyke swarms. In this study, we present zircon U-Pb ages which show that the timing of dyke emplacement as ca. 120 Ma, which followed the crystallization of the (quartz-) diorite porphyry at ca. 130 Ma. These ages coincide with the peak ages reported for magmatism and metallogeny in the central North China Craton. The various ages (2450–2570 and 154 Ma) from the inherited zircon crystals in these rocks suggest that substantial lower to middle crustal basement rocks and Jurassic granitoids were involved during dyke emplacement. The dyke swarms, varying between alkaline and subalkaline, are compositionally low-Si low-Ti lamprophyre and low-Si high-Ti dolerite porphyry in the western of the Jiaodong peninsula, whereas those in the eastern part are composed of both high-Si low-Ti and low-Si high-Ti lamprophyres. These features imply multiple sources for the dykes from convective asthenospheric mantle to ancient enriched lithospheric mantle with magma generation at different depths involving mixture of slab-derived hydrous fluids. The source magmas of the dykes were hydrous and enriched in volatiles as well as ore components, and their evolution occurred under high oxygen fugacity conditions. The relatively rapid emplacement and cooling of the dyke systems enabled the migration of fluids into ore-controlling faults or fractures. We envisage that the dyke swarms played an important role in generating the world-class gold mineralization of Jiaodong. [ABSTRACT FROM AUTHOR]

The Jiawula Ag–Pb–Zn deposit is located in the northern part of the Da Hinggan Mountains metallogenic belt in the eastern section of the Central Asian Orogenic Belt. Sphalerite, galena, pyrite, chalcopyrite, and arsenopyrite are the major sulfide minerals occurring in this deposit. Here we report results from electron probe micro-analysis (EPMA), thermoelectricity, and sulfur isotope studies of the constituent silver minerals and sulfide phases of the Jiawula deposit. Petrographic observations and EPMA study reveal abundant silver mineralization in the ore, especially within sphalerite and galena. Discrete grains of silver minerals (including argentite, pyrargyrite, and canfieldite) and isomorphism in silver-bearing sulfides are identified. Silver and tellurium contents in galena are relatively high and show interrelationship. Significant substitution of S by Te in the galena lattice facilitates silver entering the galena structure, which might have been promoted by relatively low lg f S 2 . The thermoelectric coefficient of pyrite shows a marked gradient from N-type to P-type from pre- to post-metallogenic stages. Pyrites in Jiawula are enriched in Co and As and in the absence of Ni, displaying features typical of epithermal deposits. The isotopic data present a close relationship between the sulfur source and magmatism. [ABSTRACT FROM AUTHOR]

The Fushan iron ores, located in the southern part of the Taihang Mountains (TM) within the Trans-North China Orogen, is among the medium-sized skarn iron deposits in China. In this paper we report U–Pb age data on zircon grains from the magmatic intrusion related with the skarn formation and from the Neoarchean metamorphic basement in the area. The results show that the dioritic intrusion which generated the skarn mineralization was emplaced at 128.8 ± 1.9 Ma. Zircon grains from the basement rocks and xenoliths, as well as inherited zircon in the dioritic intrusion show Neoarchean to Paleoproterozoic ages, corresponding to similar ages reported from elsewhere in the North China Craton. Our results and those from previous studies suggest that the continental lower crust was the major source of Mesozoic magmatism and associated ore mineralization. The Mesozoic magmatism and metallogeny in the Fushan region correlate with the peak of lithospheric destruction of the North China Craton. [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 Wutai-Hengshan region in the northwestern domain of Taihang Mountains (TM) occurs along the Trans-North China Orogen (TNCO) that amalgamates the Western and Eastern Blocks of the North China Craton (NCC). The metamorphic basement in the region is composed of ca. 2.5 Ga granite-greenstone belts within which the Mesozoic magmatic suites are widely emplaced, associated with polymetallic mineralization. The timing, origin and evolution of the magmatic rocks in the Wutai-Hengshan region provide important clues to evaluate the timing, mechanism and process of the destruction of the NCC. In this study, we report new zircon U–Pb and in-situ Hf isotopic data on some of the Mesozoic intrusions associated with Au–Ag–Cu–Mo mineralization from this region. The results show that magmatism and metallogeny in the Yixingzhai and Boqiang-Gengzhuang mining regions occurred during 142–130 Ma, starting with felsic granite porphyry with Mo–Cu mineralization, and intermediate magma associated with gold mineralization. The emplacement of magma and mineralization in Diaoquan mining region occurred about 132–130 Ma, with the intermediate magma emplaced earlier than felsic magma. The in-situ Hf isotopic data indicate that most of the felsic magma was produced by partial melting of the lower crust, and that the intermediate magma witnessed intrusion of mafic magma derived from mantle with magma mixing in different proportion. The process of crystallization differentiation played an important role in the formation of Diaoquan complex intrusion. The magmatism and metallogeny in the Wutai-Hengshan region were coeval with the craton destruction of the NCC. The Mesozoic magmatism and metallogeny in this region during 142–130 Ma contributed to the destruction of the stable cratonic architecture of the NCC. The mafic lower crust was modified by magma derived from mantle during this process. The regional geodynamics associated with these processes are correlated to the subduction of the paleo-Pacific oceanic lithosphere. [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: The link between metallogeny and craton destruction in the North China Craton (NCC) remains poorly understood, particularly the mechanisms within the interior of the craton. In this overview, we summarize the major stages in the history of formation and evolution of the NCC, the spatio-temporal distribution and types of major ore species, as well as mantle contribution to the metallogeny, in an attempt to evaluate the geodynamic settings of metallogeny and the mechanisms of formation of the ore deposits. The early Precambrian history of the NCC witnessed the amalgamation of micro-blocks and construction of the fundamental tectonic architecture of the craton by 2.5Ga. The boundaries of these micro-blocks and the margins of the NCC remained as weak zones and were the principal locales along which inhomogeneous destruction of the craton occurred during later tectonothermal events. These zones record the formation of orogeny related gold, copper, iron and titanium during the early to middle Paleoproterozoic with ages ranging from 2.5 to 1.8Ma. The Early Ordovician kimberlite and diamond mineralization at ca. 480Ma, the Late Carboniferous and Early to middle Permian calc-alkaline, I-type granitoids and gold deposits of 324–300Ma, and the Triassic alkaline rocks and gold–silver-polymetallic deposits occurring along these zones and the margins of the blocks correlate with rising mantle plume, southward subduction of the Siberian plate and northward subduction of the Yangtze plate, respectively. The voluminous Jurassic granitoids and Cretaceous intrusives carrying gold, molybdenum, copper, lead and zinc deposits are also localized along the weak zones and block margins. The concentration of most of these deposits in the eastern part of the NCC invokes correlation with lithosphere thinning associated with the westward subduction of the Pacific plate. Although magmatism and mineralization have been recorded along the margins and few places within the interior of the NCC in the Jurassic, their peak occurred in the Cretaceous in the eastern part of the NCC, marking large scale destruction of the craton at this time. The junctions of the boundaries between the micro-continental blocks are characterized by extensive inhomogeneous thinning. We propose that these junctions are probably for future mineral exploration targeting in the NCC. [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 Jinchang gold deposit is located in the easternmost portion of the Central Asian Orogenic Belt (CAOB), and represents one of the major gold districts in eastern Jilin–Heilongjiang provinces of China. The gold ore bodies are hosted mainly in altered Mesozoic granitoids, breccia pipes and ring and radial faults. Gold mineralization consists of alteration (stockwork in hydrothermally altered granites), breccia, and quartz-sulfide vein-types. Alteration assemblages around the alteration-style ore body show a vertical sequence of potassic, phyllic, and propylitic zones. In this study, we present U–Pb and Lu–Hf isotope data on zircons derived from mineralized granophyric granite, biotite monzogranite, granodiorite, and granite porphyry, and sericite Rb–Sr ages from the Jinchang gold deposit. The results show 206Pb/238U ages of 201±3Ma (MSWD=1.1), 203±4Ma (MSWD=1.4), 201±5Ma (MSWD=2.1), and 110±3Ma (MSWD=1.6), respectively. Sericite from the gold-mineralized phyllic-altered granodiorite and granite porphyry returns Rb–Sr isochron ages of 110±4Ma (MSWD=1.04) and 107±5Ma (MSWD=0.91), respectively. Our new data indicate that the gold mineralization at Jinchang took place at ca. 110Ma and was temporally related to intrusion of the granite porphyry. Zircon ε Hf (200Ma) values of the ca. 200Ma granites vary from −4.8 to +8.1, with TC DM model ages of 727–1535Ma, reflecting their derivation mainly by partial melting of juvenile Proterozoic crust. The gold-bearing 110Ma granite porphyry returns ε Hf (110Ma) values in the range of −1.6 to +9.8, with TC DM model ages of 542–1069Ma, suggesting partial melts of juvenile Proterozoic crust with notable input of mantle components as compared to the ca. 200Ma granites. Compiled oxygen (δ18OSMOW =−0.7–10.1) and hydrogen (δDSMOW =−99 to −70) stable isotopic values of quartz from ores indicate that the ore-forming fluids were predominantly exsolved from magmas with minor amount of meteoric water in quartz-sulfide veins at the late stage. The Hf isotope data from the granite porphyry, integrated with the results from previous data on S and Pb isotopic composition of ores, constrain the source of ore-forming components as lower crust with discernible mantle inputs and wall rock assimilation. Our results have implications bearing on the widespread magmatism and metallogenic event during the Early Cretaceous time in East China, and link them to mantle upwelling that contributed both heat and volatiles for crustal melting and scavenging of metals which in turn were concentrated in upper crustal levels through exsolution for the magmas. [ABSTRACT FROM AUTHOR]

Abstract: The large scale Mesozoic magmatism and related metallogeny in the Taihang Mountains (TM) provide important clues for the lithospheric thinning of the North China Craton (NCC). Among the ore deposits, the vein gold mineralization of Shihu in the Fuping region and the skarn ore deposit of Xishimen in the Wu''an region represent typical Mesozoic metallogeny in the TM. In the Shihu gold mine, the Mapeng batholith is dominantly composed of monzogranite and granodiorite, whereas, the Wu''an pluton in the Xishimen iron mine mainly comprises monzonite and diorite. Here we present zircon LA–ICP-MS U–Pb data from 8 samples which reveal the timing of magmatism in the TM as ca. 130Ma, which is contemporaneous with the large-scale metallogeny in the margins of the NCC. The δ34S values recorded in the sulfide minerals from the Shihu gold deposit and the Xishimen skarn iron deposit show a range of 2.2‰–5.0‰, and 11.6‰–18.7‰, respectively. Helium isotopic compositions of fluid inclusions in pyrite from the Shihu gold deposit vary from 0.12 to 1.98Ra (where Ra is the 3He/4He ratio of air=1.39×10−6), with calculated mantle helium values of 1.4%–25%, whereas, those of the Xishimen skarn iron deposit range from 0.06 to 0.19Ra, with calculated mantle helium of 0.7%–2.2%. The S–He–Ar isotopic data suggest a lower crustal origin for the ore-forming components, with variable inputs of mantle source. The large population of inherited zircons in our samples, with 207Pb/206Pb ages ranging between 2500Ma and 1800Ma, also supports crustal participation. Our data reveal that the Shihu gold deposit witnessed greater mantle input than the Xishimen skarn iron deposit, suggesting that the continental lithosphere is markedly thinner under the Fuping region than that under the Wu''an region. Our interpretation is also supported by published data from two ultra-broadband high-precision magnetotelluric sounding profiles across the TM region showing a variation in the lithosphere thickness from 155km to 70km while moving from the south (Wu''an region) to the north (Fuping region). Our study suggests that inhomogeneous lithospheric thinning in the central NCC occurred at least as early as ca. 130Ma ago. [Copyright &y& Elsevier]

Abstract: Neoarchean potassic meta-granites occurring in the Huai''an Complex within the north central part of the North China Craton (NCC) comprise leucocratic syenogranites, biotite monzogranites, and garnet-bearing syenogranites. High-pressure garnet–granulites occur as lenses, sheets or dismembered dikes with the granitoids. Here we present SHRIMP zircon U–Pb data from the leucocratic syenogranites which show an age of 2493±6Ma (MSWD=1), and LA-ICP-MS U–Pb data from the biotite-monzogranites and garnet–syenogranites, revealing their formation ages of 2437±10Ma (MSWD=2.0) and 1977–2003Ma, respectively. We also report metamorphic ages of ca. 1800Ma from zircons in the garnet–syenogranites. Geochemical studies show low MgO (0.5–0.06wt.%), Cr (6.19–0.53ppm) and Ni (27.66–2.01ppm) with varying SiO2 (62.3 to 76.8wt.%) contents, indicating their derivation from a crustal source. The leucosyenogranites exhibit elevated positive Eu anomalies with decreasing Sr, Th, U, and bulk REE concentrations, and Th/U ratio, whereas Rb and Ba values increase with decreasing Th/U ratio, indicating fluid–melt interaction. The leucosyenogranites have high Sr and Ba contents and Sr/Y and (La/Yb)N ratios and low Y and HREEs, with zircon εHf(t) values ranging from +1.7 to +5.8 and Hf model ages of 2.60–2.73Ga, reflecting their derivation by partial melting of overthickened juvenile lower crust of eclogitic composition, or an eclogitic mineral assemblage in the residue. Geochemical compositions of the biotite–monzogranites, with positive εNd(t) values (+2.3 to +2.5) and model ages <2.60Ga, indicate that they are evolved partial melts from a thickened juvenile crust of garnet amphibolite composition, or with garnet and amphiboles in the residue, followed by fractionation dominated by plagioclase precipitation. The garnet–syenogranites display variable contents of SiO2 (62.3–72.3wt.%), and relatively high Zr (491–1096ppm), Ga (23.5–31.2ppm), Zn (38–124ppm), Y (34.1–85.6ppm) and Nb (9.4–90.0ppm) abundances with 104 ×Ga/Al ratios of 3.1–4.2. They also possess low Sr (50–161ppm) concentrations and strong negative Eu anomalies. These features, integrated with Nd model ages of 2.46–2.50Ga and relatively constant negative εNd(t) values (−2.5 to −2.9) with increasing SiO2 contents, suggest A-type granitic affinities of intraplate extensional or rift setting with evolution of the magma from partial melts derived from Neoarchean tonalitic rocks. The distinct geochemical features and zircon saturation temperatures of the granitoids are indicative of high melting temperatures (900–1000°C) at relatively low pressures (6–10kbar). Based on previous works and our new data, we link the ca. 2500–2450Ma and 2000Ma magmatic events to a Neoarchean amalgamation of microblocks and Paleoproterozoic mobile belts. The metamorphic ages of 1800–1820Ma might reflect an amphibolite facies retrograde event. [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]

The Jiaodong type comprises a unique class of gold mineralisation which includes the Linglong type quartz-vein hosted and the Jiaojia type fracture-disseminated style deposits. Although the type area is in the Jiaodong Peninsula in NE China, where some of the world's richest gold reserves occur, we identify similar occurrences in other parts of China and elsewhere in the world under this category. The ore fluids migrated upwards forming quartz vein type of gold ore (Linglong type) wherever the ore-controlling fractures are at high angles. Fluid infiltration into the surrounding wall rocks and generation of the Jiaojia type disseminated style deposits resulted where the ore-bearing fluids encountered low angle fractures. On a regional scale, the Jiaodong type gold mineralisation occurs along the margins of reactivated cratons, within the interior of cratons along paleosuture zones, or along the junctions of micro-blocks, and is distinctly different from the classic orogenic gold in terms of their tectonic setting, ore characteristics and genetic history. Unlike skarn and porphyry type of deposits, the Jiaodong type gold deposits do not always show close spatial relationship with magmatic intrusives and some of the deposits occur distal to plutons (> 10 km). In this paper, we evaluate the salient geological, geochronological, geochemical and isotopic features of the Jiaodong type gold deposits and propose some general guidelines for gold prospecting. Based on case studies, we predict that the gold lodes in the Jiaodong type mineralised zones might extent vertically up to 3000 m with only minor mineralogical and geochemical variations. [ABSTRACT FROM AUTHOR]

The Trans-North China Orogen (TNCO) along the central part of the North China Craton (NCC) is considered as a Paleoproterozoic suture along which the Eastern and Western Blocks of the NCC were amalgamated. Here we investigate the Precambrian crustal evolution history in the Fuping segment of the TNCO and the subsequent reactivation associated with extensive craton destruction during Mesozoic. We present zircon LA-ICP-MS U–Pb and Lu–Hf data on TTG (tonalite–trondhjemite–granodiorite) gneiss, felsic orthogneiss, amphibolite and granite from the Paleoproterozoic suite which show magmatic ages in the range of 2450–1900 Ma suggesting a long-lived convergent margin. The ε Hf ( t ) values of these zircons range from −11.9 to 12 and their model ages suggest magma derivation from both juvenile components and reworked Archean crust. The Mesozoic magmatic units in the Fuping area includes granite, diorite and mafic microgranular enclaves, the zircons from which define a tight range of 120–130 Ma ages suggesting a prominent Early Cretaceous magmatic event. However, the ε Hf ( t ) values of these zircons show wide a range from −30.3 to 0.2, indicating that the magmatic activity involved extensive rejuvenation of the older continental crust. [ABSTRACT FROM AUTHOR]

The Luxi area in the central part of Eastern North China Craton (NCC) is located in a relatively stable intraplate environment and preserves some of the large granite–greenstone belts in the North China Craton (NCC). The intensity and extent of multiple magmatic pluses associated with the destruction of the NCC during Mesozoic were comparatively less in this region. However, the nature and timing of the magmatic pulses in the Luxi area are critical to the evaluation of the differential destruction of the NCC's lithosphere as well as in understanding the origin and extent of the associated gold mineralization. In this study, we report new zircon U−Pb data on the basement rocks in the Luxi area which show that the protoliths of the TTG (tonalite–trondhjemite–granodiorite) gneisses, granitoids and amphibolites formed at 2572.2±8.8Ma, 2531±12Ma, and 2572±32Ma respectively. The Luxi area experienced two major crust accretions at 2.7−2.75Ga and ca. 2.5Ga. The Mesozoic Tongshi complex formed at 175.6±1.7−178.4±2.1Ma associated with fluid modification at the later stage of magma crystallization. The alteration age (162.2±3.2−165.4±2.8Ma) may represent the mineralization age of the Guilaizhuang gold deposit. The diorite porphyry of Tongjing complex was emplaced at 128.0±5.4Ma. The inherited zircon and Lu−Hf isotope data suggest extensive recycling of basement rocks in the Luxi area. The sequence of Mesozoic magmatic intrusions shows a clear variation from intermediate (alkaline) through intermediate (cal-alkaline), and felsic–mafic, and the main intrusive ages can be divided into distinct phases at 170–200Ma, 100–150Ma (with peak at 120–130Ma), and 80–90Ma respectively. The Tongshi complex formed during the compression–extension stage after the collision of the Yangtze Craton and North China Craton, whereas the Tongjing complex and other alkaline, felsic and mafic complexes in the Luxi area formed within the geodynamic setting of Pacific subduction. The early Cretaceous magmatism also simultaneously occurred in the Taihang Mountain area (far from the plate margin) in the central part of the North China Craton, with related gold mineralization. The Mesozoic gold mineralization in Jiaodong and Luxi in the eastern, and those in the central parts of the North China Craton appear to be linked to extensive crustal recycling in an extensional tectonic regime. [ABSTRACT FROM AUTHOR]

The Mesozoic lithospheric destruction of the North China Craton (NCC) in eastern China with a concomitant large-scale crustal exhumation has been widely accepted. However the specific timing, magnitude and rate of exhumation remain elusive. The widely outcropping episodes of Mesozoic granitoids in the Jiaodong Peninsula provide an excellent natural case for crustal exhumation research. Application and comparison of two Al-in-hornblende barometers and experimental Qz-Ab-Or phase diagram indicate that oxygen fugacity could affect pressure estimation of granitoids and the Al-in-hornblende barometers derived from the AS95 (referring to Anderson and Smith, 1995) has the potential to estimate pressures of granitoids emplaced at 1–2 kbar. The Qz-Ab-Or phase diagram can be used to constrain the emplacement pressures of granitoids on the premise of selecting suitable geochemical data. Our results demonstrate a rapid crustal exhumation event between ∼160 and 115 Ma, i.e., approximately 10 km for the Jiaobei terrane and 7 km for the ultra-high pressure metamorphic terrane, reflecting heterogeneous exhumation possibly in response to the lithospheric destruction of the NCC. [ABSTRACT FROM AUTHOR]

The North China Craton (NCC) hosts the world's most typical example of "decratonic" gold deposits including lode, porphyry, cryptoexplosive breccia, and skarn subtypes. The lithospheric structure in the ore fields show "triple-junctions" of basement microblocks, zones of lithospheric thinning, and "hotspots" with abnormal crustal heat flow. The basement rocks are dominantly composed of trondhjemite-tonalite-granodiorite (TTG) suite and amphibolites. The intermediate-felsic calc-alkaline plutons with crust-mantle mixed origin and formed under high oxygen fugacity, volatile-rich and moderately fractionated conditions, together with dyke swarms of diverse compositions are indicators for the gold mineralization. The mantle under the gold field shows metasomatic or juvenile "EM2" or "EM2 + EM1" characteristics. The gold deposits are closely associated with craton destruction, heterogenous reactivation, large-scale magmatic intrusion and eruption, and upwelling of voluminous ore-bearing fluids within a transitional tectonic regime. The presence of mantle-derived mafic rocks, mafic microgranular enclaves (MME) and amygdaloidal bodies, minerals rich in Te, Ni, Cr, Mg, C and N, He and stable isotopes with mantle signature, among other features, indicate that the ore-forming metals and fluids have mixed mantle and deep crustal origin. Gold deposits coexisting or closely associated with mafic dykes and crust-mantle-derived stocks indicate that the upwelling of ore-forming fluid and localization of the ore-materials were facilitated at least partly by the intrusion of deep magma. The spatial distributions of altered rocks with alkali-feldspar-hematite zone distal to the orebody (barren) and pyrite-phyllite (sericite) zone proximal to the ore (ore-bearing zone) indicate a marked physico-chemical interface at the final stage of evolution of the ore-forming fluid. The presence of wide alteration zone indicates that the ore-controlling faults were in a compressive stress state, whereas narrow alteration zone is generally associated with a tensile stress state. The cataclastic, poikilitic, interstitial and zonal textures displayed by the various stages of ore minerals are related to the impact of alternating local tectonic stress fields in the faults, as well as fault-valve mechanism. Intense gold mineralization is typically associated with the development of polymetallic sulfide minerals and complex mineral assemblages. The major gold mineralization is also commonly related with pyrite with xenomorphic or complex forms, rich in As, Se, and Te, with large unit cells, wide X-ray diffraction peaks, and high P/(P + N) values corresponding to thermoelectric conductive type. Quartz grains formed in the main gold mineralization stage are generally fine grained and irregular, occasionally occurring as grain clusters, and showing complex thermoluminescence patterns with both high and low temperature peaks. Multiple rhythmic zones in quartz, pyrite or other ore minerals with various impurities in between the different zones indicate the pulses of ore fluid flow toward the upper part of the orebody. In contrast, minerals with few or no zones may indicate an ore-fluid reservoir typically in the middle to lower parts of orebody. • Indicators of decratonic gold mineralization include geodynamic background and mineralizing processes. • Five subcategories of indicators for geodynamic background are discussed. • Mineralizing processes are indicated by six subcategories of evidences. • Indicators are summarized as references for prospecting similar gold deposits elsewhere. [ABSTRACT FROM AUTHOR]

Highlights: [•] Two distinct categories of fluid inclusions were recognized in terms of temperature and salinity. [•] Unmixing of saline fluids and vapor-rich fluids directly exsolved from magmas as immiscible fluids. [•] Cu–Au metallogenic temperatures vary in range of 480–200°C. [•] It is an oxidized intrusion-related Cu–Au deposit. [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]