The Jiaodong Peninsula is a globally significant region for lode gold deposits, characterized by disseminated-stockwork mineralization and auriferous quartz-sulfide vein, but recently-discovered auriferous carbonate-sulfide vein mineralization exhibits considerable exploration potential. This study investigates the Qianchuiliu carbonate-sulfide vein gold deposit (13.5 t @ 3.02 g/t) in Jiaodong. It is characterized by three mineralization stages: quartz-K-feldspar (Stage I), dolomite-polymetallic sulfide-native gold stage (Stage II, the primary mineralization stage), and quartz-calcite (Stage III). Integrated SWIR spectral analysis and petrographic observations indicate that the Qianchuiliu deposit contains white micas (58.7 %), carbonates (35.1 %), and chlorites (6.1 %) as predominant alteration minerals. The illite crystallinity (IC) value of white micas is spatially associated with gold mineralization, with IC values >= 1.2 serving as a reliable exploration indicator. Conversely, the Al-OH absorption peak wavelength (Pos2200) of white micas shows a weak spatial correlation with orebodies. On this basis, a three-dimensional parameter model identifies the northern zone at depths of -300 to -400 m in the mining area as a priority exploration target. Regional comparisons show differences in white mica spectral parameters among disseminated-stockwork, quartz-sulfide vein, and carbonate-sulfide vein deposits, effectively distinguished using partial least squares discriminant analysis (PLS-DA). The most significant spectral parameter is white mica Pos2200 (VIP > 1.5), reflecting variations in their forming physicochemical conditions such as pH and oxygen fugacity. This study develops a SWIR-based exploration indicator system for carbonate-sulfide vein gold deposits, highlighting the effectiveness of spectral parameters in identifying mineralization and differentiating deposit types.

The mechanisms of gold mineralization, as well as post-mineralization modifications such as tectonic exhumation and preservation are critical to exploration. The Haigou deposit, located between the North China Block and the Xingmeng Orogenic Belt, is a representative Te-rich gold deposit with reserves of ∼ 40 t at an average grade of 3.4 g/t. Previous studies have focused largely on its origin, timing, ore-fluid sources, and metallodynamic setting, whereas the mineralization processes and post-ore modifications have received less attention. To address this gap, we conducted detailed field investigations, trace-element analyses of ores, apatite fission-track thermochronology, and thermal-history modeling of the Haigou deposit. Our primary objectives were to constrain the gold mineralization processes and to evaluate post-mineralization exhumation and preservation potential. Micro-textural analyses reveal that the main metallic minerals include pyrite, chalcopyrite, galena, Te-bearing galena, nickeline (NiTe2), native gold, argentite, calaverite (AuTe2), mercurian telluride (HgTe), and hessite [(Au,Ag)Te2]. Gold occurs predominantly as micro-sized native gold, nano-sized gold, and tellurides hosted in sulfides. Integration of published S-isotope and fluid-inclusion data indicates that the ore-forming materials were derived from mantle sources. Thermal-history modeling further reveals three episodes of rapid uplift at ca. 160–85 Ma, 28–14 Ma, and 8.5 Ma–present, corresponding to exhumation from depths of 5.2 ± 0.4 km. Compared with deposits that have undergone significant post-mineralization modification, the Haigou deposit is remarkably well preserved, and its ore-forming depths of ca. 5.1–9.8 km point to substantial untapped potential for gold mineralization at depth.

The Lizi gold deposit, a representative gold deposit in the West Qinling Orogen of China, has ongoing debates regarding its ore-forming material sources, enrichment and precipitation mechanisms, and metallogenic age. This study combines geological characteristics with in situ U-Pb rutile dating, trace-element of pyrite, and S-Pb isotope analyses to determine the metallogenic age and constrain the sources and processes of ore formation. Based on crosscutting relationships and mineral paragenesis, the mineralization process of the Lizi gold deposit can be divided into four stages: (1) quartz-sericite-pyrite (Stage I), (2) pyrite-gold (Stage II), (3) chalcopyrite-gold (Stage III), and (4) quartz-calcite (Stage IV). Gold primarily occurs in Stage II and III coexisting with pyrite and chalcopyrite, respectively. Rutile from Stage II yielded a metallogenic age of 211.1 +/- 6.3 Ma, indicating gold mineralization is associated to the Late Triassic hydrothermal activity. Three generations of pyrite were identified from Au-bearing quartz-sulfide veins, i.e., Py1 from Stage I, Py2 from Stage II, and Py3 from Stage III. Py2 is further divided into Py2a and Py2b according to growth zoning. From Py1 to Py3, the contents of elements such as Au, Ag, Cu, Pb, and Bi increase, and Au concentrations in pyrite remain below 10 ppm, indicating gold predominantly precipitated as visible gold (e.g., native gold, electrum, sylvanite), with only minor solid-solution incorporation in pyrite. The strong positive correlations between Au and Cu, Pb, Te, and Bi in pyrite, coupled with native gold coexisting with minerals containing these elements, collectively suggest a magmatic contribution to gold mineralization. The delta 34S values of Py1 (1.78-2.57 %o) reveal mixing sulfur characteristics of the Liziyuan Group strata (-10.47 to 1.80 %o) and syenitic rocks (2.90-9.09 %o), whereas the delta 34S values of mineralization-related Py2 and Py3 (5.59-12.18 %o) indicate a dominant syenitic magmatic source. In situ Pb isotopic compositions of galena intergrowing with gold (206Pb/204Pb = 17.971-18.312, 207Pb/204Pb = 15.553-15.654, and 208Pb/204Pb = 38.01-38.42) further support a mixed source involving Liziyuan Group strata and syenitic magmatic rocks for metallogenic materials. Collectively, this study provides compelling evidence that the formation of the Lizi gold deposit was primarily associated with Late Triassic magmatic-hydrothermal activity.

The Jiaodong Peninsula, China’s largest gold province (∼6,000 t) with significant deep exploration potential, has long been the subject of debate regarding ore sources and gold enrichment mechanisms. These uncertainties have hindered the development of a unified metallogenic model. This study integrates hydrothermal monazite U-Pb geochronology with pyrite and galena geochemistry to constrain metallogenesis and exploration vectors of the newly discovered altered rock-type Tengjia gold deposit (∼50 t @ 3.89 g/t) within the Zhaoping fault zone in the Jiaodong Peninsula. The deposit is characterized by three mineralization stages: pre-ore quartz-K-feldspar stage (Ⅰ), main-ore quartz-white micas-electrum-sulfides stage (Ⅱ), and post-ore quartz-calcite-galena-sphalerite-pyrite stage (Ⅲ).Hydrothermal monazite U-Pb dating of Stage Ⅱ mineralization yields an age of 125.5 ± 1.1 Ma (MSWD = 1.6), coincident with the regional emplacement of intermediate-basic dikes and the broader Early Cretaceous lithospheric thinning event in the eastern North China Craton. This temporal link is further supported by in-situ Pb isotope compositions of Stage Ⅱ galena, which indicate a possible ore source originating from an enriched lithospheric mantle, consistent with that of regional intermediate-basic dikes. These results suggest that the Tengjia gold deposit is genetically linked to Early Cretaceous mantle-derived magmatism associated with lithospheric thinning in the Jiaodong Peninsula. Compared with orebody-hosted Stage Ⅲ pyrite, Stage Ⅱ pyrite is depleted in Tl, As, Zn, Se, Co, Ni, and Te, indicating higher temperatures, higher oxygen fugacity (fO2), and lower pH conditions during the main mineralization stage. Elevated temperatures during Stage Ⅱ promoted intense fluid-rock interaction, and together with lower pH conditions, facilitated gold precipitation. Although increased fO2 theoretically inhibits gold precipitation, gold mineralization is temporally restricted to Stage Ⅱ, when intense fluid-rock interaction within beresitization zones promoted pyrite precipitation and the consumption of HS−, ultimately overriding the fO2 effect to trigger efficient gold deposition. Furthermore, Stage Ⅱ pyrite hosted within orebodies is systematically enriched in Ag (>0.15 ppm), As (>240 ppm), Sb (>0.09 ppm), and Ni, but depleted in Se (<1.2 ppm) relative to Stage Ⅱ wall-rock pyrite. These contrasts are controlled by physicochemical variations, with ore-proximal pyrite recording higher pH, lower fO2, lower sulfur fugacity, and relatively higher temperatures than those in altered wall-rock zones. This study provides novel genetic constraints on the Jiaodong gold deposits and highlights the potential of pyrite trace element geochemistry as an effective exploration vector for lode gold systems.

Carbonatites and syenites are commonly associated in geological complexes, but their genetic relationship has not been fully understood. This study, by integrating chronology and isotopic geochemical analyses, provides new constraints on the traditionally held "cogenetic and contemporaneous carbonatite-syenite" model, suggesting that the two units in the Yangyugou Complex did not derive from the same source at the same time, and further reveals the magmatic evolutionary processes controlling their temporal and spatial association. We studied the Yangyugou Complex, located within the Qinling Orogenic Belt, through monazite and rutile U-Pb geochronology in carbonatites, as well as in-situ analyses of trace elements and Nd isotopic compositions in apatite and monazite in syenites and carbonatites, respectively. U-Pb geochronology of rutile and monazite from carbonatites indicates consistent crystallization ages of similar to 240 Ma, corresponding to Late Triassic magmatic activity. There are significant differences in Nd isotopic compositions between apatite from syenites and monazite from carbonatites in the Yangyugou complex: the epsilon(Nd)(t) isotopic signatures of apatite extend from - 16.1 to - 10.8, while those of monazite range from -20.3 to -18.6, indicating an essential difference in their melt sources. Compared with other carbonatites in the Qinling Orogenic Belt, the Yangyugou carbonatite exhibits more negative epsilon(Nd)(t) values, indicating stronger involvement of crustal materials and/or subducted sediment-derived components. In this study, a new model is proposed in which the Yangyugou Complex in the Qinling Orogenic Belt experienced two distinct magmatic events. The first, Silurian syenite (similar to 438.9 +/- 3.3 Ma), generated by lower crust partial melting and metasomatized mantle source, while the second, Late Triassic carbonatite magmatism mixed with REE- and CO2-enriched slab fluids and melt of deep-sea sediments (similar to 240 Ma), intruded along structural pathways into the pre-existing syenite. Their contrasting ages and sources indicate that the two rock types are genetically independent, reflecting the complex multi-stage magmatic evolution of the belt.

The Qianchuiliu gold deposit, newly discovered in recent years on the northeastern margin of the Jiaolai Basin, is a pyrite-carbonate vein-type gold deposit. Unlike the previously known altered-rock and quartz-vein-type gold deposits, its gold mineralization is closely associated with pyrite mineralization and ankerite alteration. Together with the nearby Liaoshang and Xilaokou deposits, it forms a pyrite-carbonate vein-type gold metallogenic belt. The Qianchuiliu deposit contains approximately 13.5 tons of Au reserves, with an average grade of 3.47g/t. Seventeen gold orebodies have been identified, dominated by pyrite-sericite-altered granitic breccia and pyrite-carbonate vein types. The mineralization can be divided into three stages: the pyrite-sericite stage, the gold-pyrite-ferrodolomite stage, and the dolomite stage, with the main mineralization corresponding to the gold-pyrite-ferrodolomite stage. Dolomite from the dolomite stage shows delta C-13(V-PDB) values of -3.9 parts per thousand to -3.3 parts per thousand (average -3.6 parts per thousand) and delta O-18(V-SMOW) values between 9.1 parts per thousand and 10.5 parts per thousand (average 10.1 parts per thousand), exhibiting varying degrees of depletion relative to the marble of Jingshan Group. In-situ sulfur isotope analyses of pyrite from the three mineralization stages yield delta S-34 values ranging from 10.2 parts per thousand to 10.7 parts per thousand (average 10.4 parts per thousand), suggesting a mixed magmatic-hydrothermal and upper crustal Jingshan Group signature. Considering regional geological events such as Pacific Plate subduction, asthenospheric upwelling, and the tectono-magmatic evolution of the Jiaolai Basin, the Qianchuiliu pyrite-carbonate vein-type gold deposit likely formed from deep-sourced, ore-bearing hydrothermal magma derived from metasomatized, enriched mantle material. During its ascent, the fluid assimilated components from the Jingshan Group, forming a crust-mantle mixed-source fluid. Ultimately, within the detachment structures along the basin margin, abrupt changes in physicochemical conditions-such as steep structural angles and rapid temperature drops-led to gold precipitation, forming the pyrite-carbonate vein-type gold deposit.

The Lomagundi Carbon Event (LE), the large, long-lived Paleoproterozoic positive carbon isotope excursion, is traditionally associated with a significant increase in atmospheric oxygen. However, the magnitude and extent of atmosphere-ocean oxygenation during this critical period of Earth's history remain poorly constrained. Here, we present molybdenum isotope data and Ce anomaly values of Paleoproterozoic Jingshan Group marble samples deposited coincident with the peak of LE. Analyzed samples are characterized by near-modern seawater delta 98Mocarb values (maximum = 2.13 %o +/- 0.05), crustal Ce anomalies (average = 1.03), and delta 98Mocarb values (average = 0.41 %o). The great variation of Mo isotope values displayed by samples recovered from a thin stratigraphic interval likely reflect the existence of a small Mo reservoir during LE. We suggest that Mo removal from poorly oxygenated oceans under ferruginous conditions was responsible for the contraction of the Mo oceanic reservoir. Mo concentrations and isotope values of deposits coincident with this time interval appear to have been controlled by iron and manganese oxides shuttle. Placed in the context of Earth's oxygenation history, our findings suggest that O2 levels of the atmosphere-ocean system remained much less (1 % PAL) than the present level with occasional episodes of increased or pulsed atmospheric oxygen during the peak of LE.

The Tongling ore-cluster region is a major copper-gold polymetallic mining district situated within the MiddleLower Yangtze Metallogenic Belt of eastern China. Recent explorations have identified the Cishan gold deposit as a porphyry-skarn mineralization within the Shizishan ore field in the Tongling region. This study presents a comprehensive investigation of the Cishan gold deposit, encompassing geochronological, mineralogical, geochemical, fluid inclusion, and Sr-Nd-Hf isotopic studies of metallogenetic intrusive rocks and ore-bearing skarn samples. Additionally, geological modeling informed by drill-hole and gravity data were conducted. Multi-mineral U-Pb dating indicates that skarn mineralization in the Cishan deposits occurred at 138-134 Ma, succeeding the associated magmatism (139-138 Ma). Both the pyroxene diorite and quartz monzonite exhibit metaluminous characteristics and belong to the high-K calc-alkaline-to-shoshonitic series. Pyroxene diorite samples yield similar whole-rock epsilon Nd(t) values (-8.2 to -8.8) and zircon epsilon Hf(t) values (-8.6 to -12.1) to those of the quartz monzonite samples (-7.2 to -7.3 and -7.7 to -15.4, respectively), suggesting a common magmatic source. Geochemical analysis indicated that the pyroxene diorite originated from an enriched lithospheric mantle source, whereas the quartz monzonite evolved from a dioritic magma chamber. Skarn formed via hydrothermal activity at magma-wallrock contacts, and fluid inclusion analysis implied earlier high to medium temperature and high-salinity fluids formed silicates, and later cooling precipitated sulfides/carbonates. During the Early Cretaceous, the lithospheric extensional setting could induce partial melting of the lithospheric mantle, which initiated by the rollback of the subducted Paleo-Pacific slab. This process led to the formation of a deep magma chamber within the lower crust via magmatic underplating. Subsequent magma differentiation within a shallower chamber culminated in the emplacement of shallow-level stock, apophysis and dike intrusions. These intrusive bodies were instrumental in the genesis of intrusive sequences and development of gold-bearing skarn deposits.

>1. Objective Three stages of Mesozoic magmatic activity have been identified in the Jiaodong area, namely early magmatic emplacement, the magmatic emplacement prior to mineralization, and magmatic activity post-mineralization,from early to late. Of these, the early magmatic emplacement,spanning 166 Ma to 142 Ma, primarily involved crust-derived magma and occurred throughout the Jiaodong area. The magmatic emplacement prior to mineralization, characterized predominantly by crust-derived magmas, was confined to the northwestern Jiaodong Peninsula at 130-123 Ma. The last stage, magmatic activity post-mineralization, occurred between 120 Ma and 108 Ma, peaking at 115 Ma. Magmas in the Jiaodong area are chiefly derived from crust-mantle mixing, with magmas of this source widely spreading across the area. Meanwhile, A-type granites are found along the southern margin of the Jiaolai Basin.

Numerous Mesozoic porphyry-skarn Cu-Au deposits occur in the Middle-Lower Yangtze River metallogenic belt (MLYRB), but their genetically related intermediate-sulfidation (IS) epithermal deposits are rarely reported. The recently discovered Paodaoling deposit (> 35 t Au averaging 1.73 g/t) offers an opportunity to address this gap. The IS epithermal mineralization, structurally controlled by NE-trending faults, is hosted in late Mesozoic granodiorite-quartz diorite porphyries and Silurian sedimentary rocks. There are four vein stages: Stage I quartz-carbonate-polymetallic sulfide veins with minor sulfosalts of Cu-rich phases; Stage II quartz-sphalerite-galena-pyrite ± barite veins featuring various Cu-poor Pb-sulfosalts; Stage III fine-grained pyrite-marcasite-quartz-barite ± realgar ± orpiment veins; and Stage IV barren carbonate-barite ± quartz veins. Gold is invisible in arsenian pyrite and arsenopyrite. Prevalent illite-quartz-pyrite ± carbonate alteration is closely associated with mineralization. The trend in illite crystallinity (0.8–3.5) predicts a hot center at depth around the Paodaoling South Zone. The δ18Ofluid values equilibrated with quartz indicate a predominantly magmatic fluid source for early stages (I-II: 4.5 to 12.7‰, V-SMOW) and gradual meteoric water involvement in late stages (III-IV: 0.5 to 6.1‰). In-situ Rb-Sr dating of hydrothermal white mica coexisting with auriferous pyrite yields ages of 134–132 Ma, later than the host intrusions (148–141 Ma; zircon U-Pb) and main porphyry-skarn mineralization (150–135 Ma) in the MLYRB. The aforementioned lines of evidence support that mineralizing fluids were from a younger hidden intrusion. The preservation of Paodaoling implies potential to find other IS veins within or beneath the extensive early Cretaceous volcanic-sedimentary sequences in the MLYRB.

The Lomagundi-Jatuli Event (LJE) represents perhaps the largest and longest positive carbon isotope excursion of Earth history. However, the synchroneity, scale, and linkage of the LJE to Earth's early history of atmospheric oxygenation remain controversial. Strata of the Paleoproterozoic Jingshan Group of the North China Craton that preserve the isotopic record of the LJE excursion in marble layers and abundant graphite deposits provide an opportunity to elucidate the significance of the LJE. Carbon isotopic values (delta 13 C V-PDB ) of the LJE based on analysis of 20 samples of the Lugezhuang Formation, lower Jingshan Group, range from-0.8 to +9.6 %o and display positive co-variance with stable oxygen isotope values (delta 18 O V-PDB ). The positive carbon isotope excursion is constrained to 2140.6 +/- 8.5 Ma (MSWD = 0.82, n = 25) based on magmatic zircon U-Pb geochronology of biotite granulite. Variation of facies-dependent carbon isotope values, the presence of graphite deposits of the Douya Formation, upper Jingshan Group, and the absence of a Ce anomaly in PAAS normalized REE patterns of marble samples suggest that the positive carbon isotope excursion is not linked to a marked increase of organic carbon burial and associated significant atmosphere oxygenation. Elevated concentrations of iron and PAASnormalized middle REE enrichment of analyzed Jingshan Group marble samples point to anoxic and ferruginous oceanic conditions during accumulation of Jingshan Group carbonate. A positive Eu anomaly (average = 1.58), low La (average = 0.23), (Nd/Yb)N (average = 1.27), and Y/Ho (average = 36.6) anomalies, and negative iron isotope values (average delta 56Fe =-0.12 %o) are consistent with accumulation of Paleoproterozoic Jingshan Group carbonate in a restricted marine setting that was affected by high temperature hydrothermal fluids. Enrichment of the studied samples in heavy carbon isotope suggests elevated bio-productivity in the restricted, redox stratified marine setting in which Jingshan Group carbonate accumulated. Thus, it is likely that the positive stable carbon isotope excursion associated with Jingshan Group strata as well as other contemporaneous isotope excursions are local signals that are linked to a global perturbation of the carbon cycle.

Lode gold deposits are the primary source of global gold resources and possess significant mineralization potential at depth, necessitating new strategies to locate deep concealed orebodies. The Tengjia Au deposit, a newly-discovered concealed altered rock-type lode gold deposit (50 t @ 3.89 g/t), is located within the Zhaoping metallogenic belt of the illustrious gold-rich Jiaodong peninsula in Eastern China. It is distinguished by pervasive phyllic alteration associated with gold mineralization, making it an ideal target for mineral geochemical exploration in lode gold deposits. The mineralization and alteration at Tengjia unfold across three distinct stages, delineated by mineral assemblages and textural relationships: K-feldspar-quartz (I), quartz-sericite-native goldsulfide (II), quartz-calcite-galena-sphalerite (III) stages. Systematic analysis of short wavelength infrared (SWIR) spectra, coupled with petrographic observation, has unveiled an abundance of white micas (montmorillonite, muscovite, illite, paragonite, and phengite) within Stage II at Tengjia. The Al-OH absorption feature wavelengths (Pos2200), as well as illite crystallinity (IC) values, exhibit a discernible shift towards longer wavelengths (>2204 nm) and higher values (>1.4) in the vicinity of ore deposition, which likely resulted from intense water-rock interaction between ore-forming fluid and wall rocks. Discriminant analysis of the orthogonal partial least squares method (OPLS-DA) shows that the absorption wavelengths corresponding to Water, -OH, and Al-OH effectively differentiate between ore and wall-rock samples. Additionally, analysis using the random forest algorithm (RF) demonstrates that spectral data from Tengjia white micas can reliably classify orebodies, achieving an accuracy of 83.2 %. Hence, the findings suggest that the unique SWIR spectral features of white micas offer a valuable tool for detecting the concealed Tengjia gold mineralization. This study proposes a novel approach that integrates machine learning technology with SWIR analysis for the identification of concealed lode gold deposits.

Jurassic-Cretaceous magmatic rocks are widely distributed in the Jiaodong area, North China. These magmatic rocks are closely associated with gold deposits, but their petrogenesis and geodynamic background are still controversial. The Late Jurassic-Early Cretaceous granitic rocks exposed in the Guocheng area, Jiaodong Peninsula are the focus of this paper. Zircon U-Pb dating, Hf-O isotope and whole rock geochemical analysis are used to determine the petrogenesis of these rocks. Combined with previous data, the geodynamic processes of granite formation in different time intervals are investigated which provide new petrological evidence for understanding the magmatic-mineralization and tectonic background of the Jiaodong area. Samples were collected from the Queshan and Shazibu plutons. The Queshan pluton is a mylonite granite, one sample of which yields a U-206-Pb-238 zircon age of 156 Ma, while the Shazibu pluton is a quartz monzonite, one sample of which records a U-206-Pb-238 zircon age of 117 Ma. The two plutons have variable zircon Hf-O isotopic compositions: zircon epsilon(Hf)(t) values of the Queshan pluton are -29.2 to -22.8, and delta O-18 values are 7.30-7.84 parts per thousand, while the Shazibu pluton has relatively high zircon epsilon(Hf)(t) values (-21.6 to -21.0) and delta O-18 values of 7.48-8.43 parts per thousand. Whole-rock geochemical data shows that the Queshan pluton has high Sr/Y (60.7-169) and (La/Yb)(N) (34.6-65.9) values and low Y (3.11-10.3 ppm) and Yb (0.29-0.85 ppm) contents, akin to adakites, whereas granites of the Shazibu pluton are A-type with high Zr+Nb+Ce+Y contents (354-420 ppm) and zircon saturation temperatures (752-795 degrees C). Based on the geochemical and isotopic data, the Late Jurassic Queshan pluton is the product of partial melting of thickened lower crust of the North China Block, while the Early Cretaceous Shazibu pluton formed via fractional crystallization of mafic rocks derived from partial melting of the lower crust of the North China Block. Although both plutons were derived from the lower crust of the North China Block, the nature of the lower crust was modified by involvement of more depleted mantle-derived materials during the Early Cretaceous. From the Late Jurassic to the Early Cretaceous, the rock types (from the adakite to A-type granite) and the nature of the magma source suggest a shift in geodynamic processes. Combined with previous research, the Late Jurassic Queshan pluton is proposed to have formed under low-angle subduction of the ancient Pacific Plate, while the Early Cretaceous Shazibu pluton formed subsequently during Pacific Plate rollback and extension. The Early Cretaceous transformation of tectonomagmatic environments provided favourable conditions for the formation of large-scale gold deposits in the Jiaodong region.

The Xilaokou gold deposit with ca. 50 t of gold reserve @ 2.7 g/t represents a novel type (carbonate-sulfide vein type) of gold mineralization within the Jiaodong gold province. However, its mineralization age and metallogenic mechanism remain poorly constrained, hindering a comprehensive understanding of the ore-forming processes in the Jiaodong gold province. In this study, we employ syn-ore stage hydrothermal monazite in situ U-Pb geochronology to determine the ore-forming age of the Xilaokou gold deposit. Additionally, we conduct in situ LA-(MC)-ICP-MS elemental mapping and sulfur isotope analysis in ore-related pyrite to unravel the sulfur source(s) and provide new insights into the ore-forming processes of the Xilaokou gold deposit. Our findings reveal the following key points: (1) U-Pb dating of hydrothermal monazite in Au-bearing pyrite yields an ore-forming age of 119.9 +/- 3.0 Ma. This age is consistent with the mineralization ages (around 120 +/- 5 Ma) of other gold deposits in the region, including Liaoshang-, Jiaojia-, and Linglong-type deposits. (2) Gold in pyrite primarily occurs as micro-grains (5-20 mu m) within pyrite fissures associated with sphalerite and galena. (3) Elemental mapping and sulfur isotope analysis indicate that major Au mineralization is linked to elevated concentrations of As, Sb, and Tl, along with heavy sulfur isotope values (delta S-34 similar to 24.7 parts per thousand). (4) Early-stage Au mineralization is characterized by enrichment of As, Cu, and Bi, with normal sulfur isotopic composition (delta S-34 similar to 8 parts per thousand). We propose that the carbonate-sulfide vein type gold deposits represented by the Liaoshang and Xilaokou gold deposits in the Jiaodong gold province are genetically linked to quartz-sulfide vein and disseminated type deposits. The major ore-forming stage involved the addition of S and Au from a metamorphic massif at slightly lower temperatures. These findings highlight a new exploration direction within the North China Craton. In summary, the Xilaokou gold deposit provides valuable insights into gold mineralization processes in Jiaodong, emphasizing the importance of considering diverse deposit types and their genetic relationships in the region.

Located along the southern part of the West Qinling orogenic belt, the Yangshan gold deposit is one of the largest in China. The major gold ores of Yangshan are disseminated in metasedimentary host rocks with minor native gold amounts in stibnite‐gold quartz veins. Pyrite and arsenopyrite are the major Au‐bearing minerals. Hydrothermal muscovite from gold‐bearing quartz veins was dated using the in situ Rb‐Sr method to determine the formation age of the Yangshan gold deposit. The Rb‐Sr isochron date of the muscovite yielded 210.1 ± 5.6 Ma (MSWD = 1.2). This date is near the lower end of the period of the mineralized granitic dykes (210.49–213.10 Ma). Two stages of gold enriching process are recognized in the gold‐bearing pyrite: the first is incorporated with the Co, Cu, As, Ni enrichment; and the second is accompanied by Bi, Co, Ni, Pb, Cu, Sb concentration. The in‐situ sulfur isotopic values of pyrites show a restricted Δ34s range of –1.43 ‰ to 2.86 ‰ with a mean value of 0.43 ‰. Trace‐element mapping and in‐situ sulfur isotopic analysis of pyrite suggest that the sulfur deposits are likely derived from a magmatic source and likely assimilated by sulfur from the sedimentary bedrock. Thus, magmatism plays a critical role in the formation of the Yangshan gold deposit.

The Qinling Orogenic Belt (Central China) is a world-class rare earth element (REE) metallogenic belt in which REE deposits are mainly hosted by alkaline rocks and/or carbonatites. The newly discovered Yangyugou REE deposit, hosted by alkaline complexes in this belt, is unusual because the REE mineralization mainly takes the form of Ba-and REE-bearing minerals, such as barytocalcite. In this study, we present whole-rock major and trace elements, zircon geochronology, Hf isotopes, and mineral geochemistry to investigate the enrichment of REE and Ba and origin of this deposit. The REE-bearing alkaline complex at the Yangyugou deposit consists of syenite and carbonatite. Carbonatite exhibits higher concentrations of REE and Ba compared to syenite. The concentrations of REE and BaO in the carbonatite can be up to 6214 ppm and 22.4 wt%, respectively, and exhibit a positive correlation. The carbonatite contains numerous Ba-rich minerals, primarily comprising barytocalcite and a smaller amount of bazirite. The REE concentrations of barytocalcite range from 3059 to 10032 ppm, and the Ba concentration can be as high as 37.4 wt%. The barytocalcite is the primary carrier of REE and Ba in the Yan-gyugou carbonatite. Zircons from the syenite have a 206Pb/238U weighted mean age of 438.9 +/- 3.3 Ma (MSWD = 1.08). The epsilon Hf(t) values of these zircons range from-8.28 to-3.17, with two-stage Hf model ages of 1.61-1.93 Ga. Apatite from the syenite has initial87Sr/86Sr ratios of 0.70906 to 0.70984. Our study indicates that syenite-carbonatite complex was probably derived from the enriched mantle that has been metasomatized by a Ba-rich fluid, and that the early Silurian alkaline magmatism may be related to the opening of the Erlangping back-arc basin.

北大别山火山岩由于缺少精确的年代学资料和系统研究,其岩石成因背景和成岩成矿时代尚不清楚.通过对北大别山西段上天梯珍珠岩锆石U-Pb同位素定年和岩石主量、微量元素测试分析,表明上天梯酸性火山岩具有高硅(w(SiO2)介于71.82％～73.18％)、富碱(w(K2O+Na2O)介于7.97％～8.96％)、富钾贫钠(K2O/Na2O介于1.13～1.87)、弱过铝(A/NCK为1.00～1.15)等特点,属高钾钙碱性火山岩系列.岩石轻稀土强烈分馏、重稀土弱分馏,负Eu异常不明显(δEu=0.81～1.16),稀土分布曲线呈左高右平向右倾斜的模式.利用LA-ICP-MS锆石U-Pb同位素定年测得上天梯成矿岩石珍珠岩加权平均年龄为145±1 Ma(n=18,MSWD=0.91),代表了火山岩的喷发年限和上天梯珍珠岩矿床形成年龄.研究认为,上天梯珍珠岩成因类型为Ⅰ型火山岩相在加厚下地壳物质熔融的产物.北大别山西段陈棚组火山岩具有多期次喷发活动,喷发时限在145～130 Ma之间,为早白垩世西太平洋板片持续俯冲,造成大别山区地壳加厚,下地壳部分物质熔融的后碰撞构造环境.

The North China Craton, one of the oldest continental blocks in the world, comprises Paleoproterozoic metamorphic sedimentary formations that record the effects of multiple major events in early Earth history, including the Great Oxidation Event (GOE) and its consequent Lomagundi-Jatuli carbon isotope event (LJE). The lack of focused research on the geological record of LJE-equivalent rocks of the Jiaodong Peninsula, Shandong Province, eastern China, has hindered our understanding of the Precambrian atmospheric oxygen evolution recorded by rocks of the North China Craton. This paper considers carbon and oxygen isotope and trace element geochemical data recovered from marble deposits of the Paleoproterozoic Jingshan Group (2.20-1.90 Ga) of the Jiaolai Basin. The investigated strata display a pronounced positive 813CV-PDB excursion greater than 4.2 %o. 813CV-PDB and 818OV-SMOW values range from-3.7 %o to 5.4 %o and 4.5 %o to 18.7 %o, respectively. Positive co-variance of carbon and oxygen isotope values of the analyzed Jingshan Group samples is interpreted to reflect the effects of metamorphism and water-rock reactions. Marble deposits of the Jingshan Group experienced recrystallization, metamorphism, and silicification resulting in strong decarbonation. High amphibolite facies metamorphism may have reduced 813CV-PDB by 3 %o to 5 %o. Thus, estimated original sedimentary 813CV-PDB values of as great as +8.4 %o suggest the existence of a strong positive anomaly that may reflect the global Lomagundi-Jatuli event. Rare earth and other trace element geochemical results of the present study suggest that banded iron formation (BIF) deposits associated with the Jingshan Group marble formed in a redox stratified ocean in the Jiaolai Basin dominated by ferruginous conditions. Moreover, our results suggest that positive carbon isotope anomaly associated with the LJE is largely constrained to sediment deposited in shallow and coastal marine environments.

内蒙古大红山晶质石墨矿床位于阴山隆起的渣尔泰山中—新元古代裂谷带,矿体赋存于中—新元古界蓟县系渣尔泰山群阿古鲁沟组二段的炭质板岩中,目前共圈定矿体2条,其中Ⅰ号矿体为主矿体.本文立足于区域地质与矿产勘查资料,结合前人研究成果,在成矿地质背景、矿床与矿体特征、样品化学分析、矿石矿物赋存状态及特征研究的基础上,总结了内蒙古大红山地区晶质石墨矿床的成矿地质特征及找矿标志.研究表明:(1)大红山晶质石墨矿床是经区域变质作用而形成的区域变质型矿床;(2)该矿床的成矿物质主要来源于变质黏土岩和粉砂质页岩中的有机物;(3)含炭粉砂细晶灰岩与含炭粉砂质板岩接触部位,含矿岩石形成的负地貌是找矿的有利地区.

As the most important gold producer in China, the Northwest Jiaodong Peninsula is famous for its large gold deposits. In recent years, the discovery of gold mineralization has reached a depth of 4 000 m below the surface in this region. It has attracted significant interest from explorers about the prospecting potential at greater depths. Besides, the current deep drilling shows that the prospecting effect in the west portion is better than the region to the east. Does it imply that there is a difference in prospecting potential between the east and the west? This paper seeks to address the issue through fission track thermochronology on apatite and zircon to reveal the temperature-time evolution relationship of rock mass and to inverts their thermal evolution history. In addition, this study analyzes the transformation of ore deposits after mineralization, quantitatively calculates the uplift-erosion rate of rock mass, and summarizes the preservation law of ore deposits. Based on the thermal history simulation of the apatite fission track, our results show that the Guocheng gold belt has experienced three stages of thermal evolution: 108–74, 74–27, and 27–0 Ma. The uplift and cooling processes of the three-stage tectonic uplift events are the results of multi-stage Pacific plate accretion. The calculated total denudation depth of the gold deposit in the Guocheng gold belt from Cretaceous to the present is about 3.4–5.3 km. The metallogenic depth of the ore body in the gold belt is 5.6–8.0 km, which indicates that the ore body in the Guocheng gold belt has suffered a significant degree of denudation. It is speculated that the location with less denudation in the southwest has greater prospecting potential. Our results quantitatively identify the uplift and denudation of the deposit after mineralization, which provides a new theoretical reference for regional mineralization, deep prospecting and exploration.