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Quartz cathodoluminescence (CL) images are commonly combined with trace element concentrations to decipher complex histories of hydrothermal systems. However, the correlations between aluminum content and CL zoning of low-temperature hydrothermal quartz and their genesis remain controversial. In this contribution, a multiparametric study was carried out on CL-aluminum zoning of low-temperature hydrothermal quartz (<350 °C) from the Shihu and Rushan quartz-vein type Au deposits in the North China Craton. The results show that aluminum concentration correlates negatively with CL intensity in quartz from the Shihu Au deposit. CL-dark quartz zoning has significant Al concentrations as well as detectable Al-H bonds. However, in the Rushan Au deposit, the correlation is positive, and aluminum is enriched in the CL-bright quartz zoning. The Al content is positively correlated with K content with r2 = 0.769. Combined with the electron backscatter diffraction (EBSD), X-ray single crystal diffraction (XRD), and transmission electron microscope (TEM) data, we infer that the genesis of CL zoning in the low-temperature hydrothermal quartz is closely related to Al3+-H+ and Al3+-K+ concentrations. The Al3+-K+ may act as the CL-activator, while the Al3+-H+ may act as the CL-dampener. Where Al3+-Si4+ substitution is charge balanced by hydrogen, the intensity of CL response decreases; where Al3+-Si4+ substitution is charge balanced by potassium, the intensity of CL response increases. The correlations between CL intensity and aluminum concentration in the low-temperature hydrothermal quartz reflect pH fluctuations of hydrothermal system. [ABSTRACT FROM AUTHOR]

The Handan–Xingtai region in the southern Taihang Mountains in central North China Craton hosts several skarn‐type iron deposits. Here we investigate an ore‐forming intrusion associated with a typical iron skarn deposit to explore the magmatic evolution from mineral zoning textures, and to constrain the ore genesis. We report results of X‐ray mapping of the composition of amphibole and plagioclase. The amphibole thermobarometers suggest: (a) magma chamber at a depth of 17 km; (b) two types of magma with different physical and chemical properties, one representing the main magma chamber with high water content, and the other characterized by more mafic composition and higher oxygen fugacity. The final emplacement depth of magma is estimated as ca. 1.5 km. The oxygen fugacity shows an obvious increase from the primary magma chamber to its emplacement depth. The zoning texture of plagioclase and amphibole suggest that the mafic magma was injected into felsic magma chamber many times, leading to magma mixing. We construct a petrogenetic and metallogenic model which envisages the following processes: (a) during 135–120 Ma, mantle‐derived magma and crust‐derived magma underwent mixing and homogenization at the crust–mantle boundary; (b) the hybrid magma rose to the middle crust and formed a magma chamber; (c) multiple injection of mafic magma into the felsic magma chamber resulted in oscillatory zoning; (d) the magma with high water content and higher modal content of plagioclase and amphibole formed through multiple magmatic injection‐mixing‐crystallization processes; and (f) the high water content and higher oxygen fugacity enabled the hybrid magma to rise to the shallow crust, where it released iron‐rich melt and fluids, which reacted with the surrounding limestones to generate the skarn‐ type iron deposit. [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]

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]

Tellurium–gold deposits differ from normal gold mineralization in their significant content of tellurium‐bearing minerals with a close relation between Au and Te. The Guilaizhuang gold deposit is a major tellurium–gold deposit in the Shandong Province of China, and is located in the eastern margin of the North China Craton. The main sulfide minerals in this deposit are pyrite, As‐bearing pyrite, arsenopyrite, chalcopyrite, galena, sphalerite, chalcocite, and argentite. Tellurides contain native tellurium, altaite, coloradoite, petzite, and calaverite. Here, we investigate the fluid characteristics based on fluid inclusion studies and evaluate the intensive variables through thermodynamic computations to evaluate the ore genesis. We identify four stages for the mineralization: quartz‐pyrite stage, gold‐polymetallic sulfide stage, gold‐telluride stage, and carbonate stage. The gold‐telluride stage represents the main stage of gold precipitation. In gold‐polymetallic sulfide stage, Au formed within pyrite and As‐bearing pyrite in the form of invisible gold, whereas in the gold‐telluride stage, Au occurs as visible gold, such as native gold, electrum, calaverite, and petzite. Our data show that the mineralizing fluids were partly acidic and reduced during the gold‐polymetallic sulfide stage. Gold was transported as AuCl2− and Au(HS)2− complexes which was reduced by Fe2+. Gold might also occur as submicroscopic Au0 inclusions in pyrite and As‐bearing pyrite. The acidic state of the fluids favoured Au leaching from the surrounding rocks. During the gold‐telluride stage, gold might have migrated mostly as Au(HTe)2− and the Te combined at first with Ag to form hessite and subsequently with Au and Ag to form petzite and calaverite. With the decrease in Te content and increase in Au saturation, tellurium and native gold were precipitated. Our study provides insights into the physicochemical conditions of the formation of Te–Au deposits. [ABSTRACT FROM AUTHOR]

The Yongxin gold deposit is a large, fracture-controlled ore deposit in the Duobaoshan gold-copper metallogenic belt within the eastern domain of the Central Asian Orogenic Belt (CAOB). Silicification, sericitization and potassic alteration are the main hydrothermal alteration types which display successive zoning surrounding the ore-bodies. Pyrite, galena, sphalerite and chalcopyrite are the major metallic minerals in the deposit, and gold is mainly distributed in pyrite. Here we investigate the trace element composition and isotope (Pb and S) characteristics of pyrite from this deposit. The auriferous pyrite is mainly allotriomorphic and homogeneous in chemistry with a homogenous distribution of As, Ni, Mo and Fe from the core to rim of grains. These features are consistent with the 207 Pb/ 206 Pb- 206 Pb/ 204 Pb, and 208 Pb/ 204 Pb- 206 Pb/ 204 Pb of the grains that suggest a single source with no evidence for involvement of late fluids. The δ 34 S values range from +3.5‰ to +5.4‰ with an average of +4.48‰, suggesting a mantle-derived magmatic provenance for the sulfur. The high Co content and Co/Ni ratios, low Ni and Mo/Ni ratios suggest a mafic/ultramafic source for the Yongxin gold deposit. The Co-Ni-As relation indicates a magmatic hydrothermal affinity with a classification as epithermal gold deposit. High arsenic and gold contents on the rims of pyrite grains indicate that Au and As were simultaneously precipitated in anoxic, low temperature and near-surface conditions. [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]

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]

• Porphyry and epithermal type of gold deposits in the hinterlands of the Bagrote valley. • Proximal source and high content of gold in pyrite suggest probable mineralization beneath the current level of erosion. • Gold occurs in pyrite in the form of micro to nano inclusions as Au0 instead of Au+1. • Ore forming fluids were derived from orogenic belts with minor contribution of lower crust. The Bagrote valley in North Pakistan, belonging to the Kohistan island arc, is well-known for regional placer gold mining. However, no economically feasible in situ hydrothermal gold deposits have been discovered in this region due to rugged terrain and remote nature of its location in the western Himalaya. The streams draining the Main Karakoram Thrust (MKT)/Shyoke suture zone carry placer gold in sediments as well as old river terraces, although the primary source remains unknown. In this paper, we employ a multiparametric approach including, X-ray Diffraction (XRD) analysis, thermoelectricity, major and trace element geochemistry and isotopic characteristics of pyrite associated with placer gold with a view to identify the nature of the unknown deposits and ore forming fluids on the catchment of the Bagrote valley. Pyrite in the Bagrote valley placers is euhedral to subhedral indicating the proximal gold sources. The high rate of occurrence of N-type thermoelectric coefficients (89%) with low P-type (11%) and crystallization temperature (290 °C−380 °C) combined with chemical features indicate that the pyrite was derived from porphyry or epithermal type of magmatic hydrothermal gold deposits from the hinterlands of the Bagrote valley. The X-Ray elemental maps show that Fe, As, Mo and Ni are homogenously distributed from core to rim suggesting stable crystallization condition without any alteration by later fluids. The calculated chemical formula of pyrite of our samples is [Au0.0006Fe] S2.004], plots of Au-As and Au-Fe shows that gold occurs in pyrite as micro to nano inclusion as Au0. The δ 34 S V - CDT values of pyrite range from – 0.6‰ to 0.9‰ with an average of −0.02‰, indicating the derivation of sulfur from a homogeneous magmatic source. The Pb isotope data indicates that the Pb was sourced from orogenic-type source, with minor contribution of lower crust. The narrow variations in 206Pb/204Pb and 208Pb/204Pb values suggest a single lead source. The low, medium and high Mo/Ni ratios reflect a mixed provenance for the auriferous pyrite. The average value of γ (71.8%), of pyrite computed from thermoelectric parameters (XnP), suggests that the dominant part of the primary source that contributes to the placers might have already been eroded. However, the proximal source and with high content of gold in the pyrite grains (up to 1160 ppm) suggest the possibility of significant economic mineralisation below the present erosion level of the deposits in the hinterlands of Bagrote Valley. [ABSTRACT FROM AUTHOR]

The Baiyun gold deposit is located in the northeastern North China Craton (NCC) where major ore types include Si-K altered rock and auriferous quartz veins. Sulfide minerals are dominated by pyrite, with minor amounts of chalcopyrite, sphalerite and galena. Combined petrological observations, backscattered electron image (BSE) and laser ablation analysis (LA-ICP-MS) have been conducted on pyrite to reveal its textural and compositional evolution. Three generations of pyrite can be identified—Py1, Py2 and Py3 from early to late. The coarse-grained, porous and euhedral to subhedral Py1 (mostly 200–500 μm) from the K-feldspar altered zone is the earliest. Compositionally, they are enriched in As (up to 11541 ppm) but depleted in Au (generally less than 10 ppm). The signal intensity of Au is higher than background values by two orders of magnitude and shows smooth spectra, indicating that invisible gold exists as homogeneously or nanoscale-inclusions in Py1. Anhedral to subhedral Py2 grains (generally ranging 500–1500 μm) coexist with other sulfides such as chalcopyrite, sphalerite and galena in the early silicification stage (gray quartz). They have many visible gold grains and contain little amounts of invisible Au. Notably, visible gold has an affinity with micro-fractures formed due to late deformation, implying that native gold may have resulted from mobilization of preexisting invisible gold in the structure of Py2 grains. Subsequently Py3 occurs as very fine-grained disseminations of euhedral crystals (0.05–1 mm) in late silicification stage (milky quartz) and coexists with tellurides (e.g. petzite, calaverite and hessite). They contain the highest level of invisible gold with positive correlations between Au-Ag-Te. In the depth profiles of Py3, the smooth Au spectra mirror those of Te with high intensities, revealing that gold occurred as homogeneously/nanoscale-inclusions and submicroscopic Au-bearing telluride inclusions in pyrite grains. The high Te and low As in Py3, combined with high Au content, imply that invisible gold can be efficiently scavenged by Te. Abundant tellurides (petzite, calaverite and hessite) have been recognized in auriferous quartz veins. Lack of symbiosis sulfides with the tellurium assemblages indicates crystallization under low fS2 and/or high fTe2 conditions and coincides with the result of thermodynamic calculations. High and markedly variable Co (from 0.24 to 2763 ppm, average 151.9 ppm) and Ni (from 1.16 to 4102 ppm, average 333.1 ppm) values suggest that ore-forming fluid may originate from a magmatically-derived hydrothermal system. Combined with previous geochronological data, the textural and compositional evolution of pyrite indicates that the Baiyun gold deposit has experienced a prolonged history of mineralization. In the late Triassic (220,230 Ma), the magmatic hydrothermal fluids, which had affinity with the post-collisional extensional tectonics on the NCC northern margin, caused initial gold enrichment. Then, as a result of deformation or the addition of new hydrothermal fluids, visible gold-rich Py2 was formed. The upwelling of mantle–derived magma brought in a lot of Te-rich ore-forming hydrothermal fluids during the peak of the destruction of the NCC (~120 Ma). Amount of visible/invisible gold and Au-Ag-Te mineral assemblages precipitated from these mineralized fluids when the physical and chemical conditions changed. [ABSTRACT FROM AUTHOR]

[Display omitted] • The isotope values and of pyrite indicate that oxygen fugacity increased slightly from stage Ⅱ to stage III. • The Rb-Sr dating on sulfide minerals from Chen'er yield an isochron age of 129.2 ± 3.4 Ma. • The metallogenic components and fluids were derived dominantly from magmatic or mantle sources. The Chen'er gold deposit, with 27 tons of known Au reserves, is one of the typical gold deposits in the Xiaoqinling district along the southern part of the North China Craton. In order to better understand the gold precipitation time and mineralization process, we report in-situ Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) trace element analyses, elemental maps, and the Rb-Sr and S-Pb isotopic composition of sulfides from the Chen'er gold deposit with a view to gain insights into the mineralization time and process. Trace element analyses and elemental maps of pyrite show that the content of As is low and has no correlation with Au, indicating As is unlikely to have controlled the Au incorporation into pyrite. Gold mainly occurs as solid solutions in the Py Ⅰ and Py Ⅱ, and as Au-Ag and/or Au-Te sub-micrometer inclusions in Py III. The Rb-Sr isotopic data on sulfides from the Chen'er deposit yielded an isochron age of 129.2 ± 3.4 Ma, which overlaps with the previously reported 40Ar/39Ar age of hydrothermal mica, indicating that the gold mineralization occurred in the Early Cretaceous. The in-situ sulfur isotope values of sulfides from stage Ⅱ to stage III fluctuate significantly (the average value decreases from 4.95 to −0.24‰) and were affected by physicochemical parameters of the mineralization process, especially ƒO 2. In addition, the δ34S values are in a narrow range (-1.34 to 5.24‰), indicating a magmatic source for the sulfur. In-situ Pb isotopic compositions of the pyrite and galena of stage Ⅱ and stage III are relatively constant with 208Pb/204Pb, 207Pb/204Pb, and 206Pb/204Pb values in the range of 37.264–37.595, 15.364–15.423, 16.992–17.078, respectively, indicating a mixed mantle-crust origin. Based on the new geochronological, geochemical and isotopic data presented in this study, and combined with those from previous studies, we suggest that the lode gold deposits in the Xiaoqinling district are magmatic hydrothermal ore deposits, with metal and ore-forming fluid originating primarily from the mantle, coupled with the cratonic reactivation during the Early Cretaceous. [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]

[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]

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]

• Helium–Argon isotopic data indicate that the ore-forming fluids were derived from crust–mantle interaction. • ΔS/Pb isotopic data indicate that ore fluids and metals were derived from a mixed source. • A close relationship between gold metallogeny and destruction of the NCC is envisaged. The Dabaiyang gold deposit is located within the Zhang-Xuan gold mineralized zone, along the northern margin of the North China Craton (NCC). The ore mineralization is hosted within Precambrian metamorphic rocks, and is a typical quartz-vein type gold deposit with minor sulfide mineralization. Here we report He-Ar, S, Pb and O isotopes from this deposit with a view to trace the source of the ore-forming fluids and metals, and to evaluate the relationship among ore-formation, magmatism and craton destruction in the NCC. The ratios of 3He/4He and 40Ar/36Ar of the fluid inclusions in the pyrite of the Dabaiyang ores show a range of 1.4Ra–1.8Ra and 4974.4–15669.5, respectively, with the concentrations of 4He and 40Ar varying from 0.8 to 6.6 (10−7 cm3 STP/g) and 4.3 to 218.1 (10−7 cm3 STP/g), respectively. Our data suggest that mixed mantle and crust derived fluids were involved in the Dabaiyang gold mineralization, with ca. 17.1%–27.6% mantle-derived helium, as computed from crust-mantle mixing model. The δ34S values in the pyrite range from −10.40‰ to −11.90‰, with an average of −10.96‰, suggesting that the sulfur in the ore forming fluids was derived from a mixed-source of the Precambrian metamorphic basement and mantle. The Pb isotopic ratios in the pyrite from the ores show 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb in the range of 16.82 to 17.16, 15.33 to 15.43 and 36.77 to 37.22, respectively, indicating that the ore forming fluids, and by inference, the ore metals, were mainly derived from lower continental crust with minor contribution of mantle. The δ18O H2O values of the fluid inclusions in the gold-bearing quartz veins range from −1.04‰ to 4.36‰, suggesting the dominant role of magmatic water with minor contribution of meteoric water in the ore precipitation. Based on the analytical results of the isotopic compositions obtained in this study, combined with the previously published geochronological and He-Ar/S/Pb/O isotopic data, we suggest that the ore fluids and metals were derived from a mixed source involving contributions from mantle, crust and atmospheric water, and that the ore formation was associated with destruction of the North China Craton. [ABSTRACT FROM AUTHOR]

• Pyrite Rb-Sr data constrain the timing of gold mineralization as Early Cretaceous. • Zircon U-Pb ages from the clasts do not correspond to the gold metallogeny. • Gold mineralization in extensional setting associated with craton destruction the NCC. The Puziwan gold deposit, located in north-western Shanxi province in North China, is a typical cryptoexplosive breccia-related gold deposit. Here we present new zircon U-Pb and pyrite Rb-Sr geochronology, and zircon Lu-Hf and pyrite S-Pb isotopic data to constrain the timing of ore formation and to gain insights into the source of the metal and genesis of the deposit. The clasts of the ore bodies of the deposit consist mainly of quartz porphyry and granulite. Pyrite and the oxidized limonite account for ∼70% of the total ore minerals associated with the entire ore-forming process. Gold is dominated by electrum and native gold which mainly occur in the interstices and fissures of pyrite. We identify six stages during the mineralization process: (1) gold-bearing quartz-pyrite, (2) quartz-pyrite-sericite, (3) quartz-sericite-Au-Ag polymetallic sulfides, (4) quartz-Ag polymetallic sulfides, (5) gold-bearing sulfide-quartz, and (6) carbonate-pyrite. The pyrite from the main mineralization stage yields Rb-Sr isochron age of 139.2 ± 1.1 Ma, suggesting that the Puziwan gold deposit formed during the Early Cretaceous, much later than the Triassic emplacement of the quartz porphyry (∼229 Ma). The S, Pb and Sr isotopic data suggest that the source of the ore is closely related to deep-seated magmatism derived through mixing of lower crust and mantle material. The geochronological and isotopic data preclude the associated Triassic quartz porphyry as the source, and suggest probable hidden deep-seated Cretaceous magmatism, forming an intrusion related auriferous system. The brecciation resulted from the cryptoexplosion and fluidization. Synchronously, or slightly after the brecciation, the ore fluids were channeled along the breccias and fractures or faults within the fracture zone. Occurrence of other gold deposits in the North China Craton which share similar geochronological and isotopic characteristics with Puziwan gold deposit indicates that these cryptoexplosive breccia-related gold deposits formed during lithospheric extension associated with craton destruction triggered by the subduction of Paleo-Pacific Plate during the Late Jurassic to Early Cretaceous. [ABSTRACT FROM AUTHOR]

• Fluid mixing might dominantly govern the precipitation and deposition of ore-forming materials. • The Rb-Sr dating of pyrite, calcite and quartz indicate that the deposit was formed at 114.6 ± 1.2 Ma. • There are great prospecting potentials in the deep northwest part of the deposit. The Yongxin gold deposit is one of the prominent gold deposits in the Duobaoshan gold-copper metallogenic belt within the eastern domain of the Central Asian Orogenic Belt. The deposit has recently been discovered therefore, its genesis and economic significance remain unknown. Here, we present the results of pyrite thermoelectricity, fluid inclusion and H-O-Rb-Sr isotopic studies of different minerals with a view to decipher ore genesis and ore prospecting in the Yongxin gold deposit. The Rb-Sr isotopic composition of pyrite, quartz and calcite indicate that the deposit was formed at 114.6 ± 1.2 Ma. Fluid inclusions and H-O isotopic studies show that the Yongxin gold deposit was formed at shallow depth, with relatively low ore-forming temperatures (120–355 °C), low-medium salinity (0 wt% to 10 wt%), and low-moderate density (0.6–1.0 g/cm3). The ore-forming fluids were mainly magmatic which mixed with meteoric water triggering the precipitation of ore-forming materials. We trace the evolution of the ore fluids from deeper levels in the northwest part of the deposit to shallower levels in the southeast. The thermoelectricity parameter values (Xnp) of pyrite range from −188 to −85 and the values of erosional or exhumation level (γ) range from 97% to 71% with an average of 79.4%, suggesting that the existing ore-body is the lower part of the deposit (79.4% of the ore-body has already been eroded). Thermoelectricity of pyrite shows a vertical distribution in the axial direction without significant change in the Xnp values, indicating that the ore body extends further. Combined with the pyrite thermoelectric coefficients in different altitudes, we predict gold potential for the ores at further depth depending on the continued presence of the N-P type pyrite. Our mineralogical mappings also suggest a prospecting potential in the two zones at depth beneath the northwestern part of the deposit. [ABSTRACT FROM AUTHOR]