Search Results (11)

The Jiaodong region ranks as the world’s third-largest gold metallogenic province, where Late Mesozoic gold mineralization exhibits close genetic connections with cratonic destruction and multi-stage plate tectonic interactions. This study systematically deciphers the deep-seated architecture and metallogenic controls through integrated analysis of gravity, aeromagnetic, and magnetotelluric datasets. The key findings demonstrate the following: (1) Bouguer gravity anomalies reveal a “two uplifts flanking a central depression” tectonic framework, reflecting superimposed effects from Yangtze Plate subduction and Pacific Plate rollback; (2) zoned aeromagnetic anomalies suggest that the Sanshandao–Jiaojia–Zhaoyuan–Pingdu Metallogenic Belt extends seaward with significant exploration potential; (3) magnetotelluric inversion identifies three lithosphere penetrating conductive zones, confirming the Jiaojia and Zhaoyuan–Pingdu faults as crust mantle fluid conduits, while the Taocun–Jimo fault marks the North China–Sulu Block boundary; and (4) metallogenic materials derive from hybrid sources of deep Yangtze Plate subduction and mantle upwelling, with gold enrichment controlled by intersections of NE-trending faults and EW-oriented basement folds. Integrated geophysical signatures indicate that the northwestern Jiaodong offshore area (north of Sanshandao) holds supergiant gold deposit potential. This research provides critical constraints for the craton destruction type gold mineralization model. Full article

The Jiaojia gold deposit in the Jiaodong Peninsula, located in the northwestern part of the Jiaodong gold province in eastern China, has a gold reserve of over 300 t. Gold mineralization in Jiaojia deposit occurred in three stages: (1) The Pyrite–Quartz–Sericite Stage (Stage I) developed primary minerals that included quartz, sericite, and a small amount of anhedral pyrite, appearing as disseminations within milky quartz and foliated sericite. (2) The Quartz–Pyrite Stage (Stage II) developed quartz that appears smoky gray and pyrite that appears with a euhedral cubic morphology, with crystal faces oriented in a longitudinal pattern. Native gold occurs as fracture filling in pyrite. (3) The Quartz–Polymetallic Sulfides Stage (Stage III) developed polymetallic sulfides, including pyrite, chalcopyrite, galena, sphalerite, and magnetite. Native gold filled the pyrite fractures and was enclosed within the pyrite. (4) The Quartz–Carbonate Stage (Stage IV) developed the main minerals of quartz and carbonate, with scattered occurrences of pyrite. In situ geochemical analysis of pyrite, the main gold-carrying mineral from mineralization Stages I to III in the Jiaojia gold deposit, was conducted, including major element, trace element, and sulfur isotope analyses. The δ³⁴S values of Jiaojia pyrite range from 4.5 to 8.0‰. Pyrite in Stage I (Py I) has δ³⁴S values ranging from 4.5 to 7.4‰, with an average of 6.4‰. Pyrite in the Stage II (Py II) has δ³⁴S values ranging from 5.9 to 8.0‰, with an average of 6.8‰. Pyrite in Stage III (Py III) has δ³⁴S values ranging from 6.4 to 7.9‰, with an average of 7.4‰. Combined with the C-D-O-He isotopes, the ore-forming fluids of the Jiaojia gold deposit likely originated from subducted oceanic plate-related metasomatized mantle. The Co/Ni ratios of Jiaojia pyrite range from 0.50 to 1.47 in Stage I, 0.27 to 1.69 in Stage II, and 0.58 to 295 in Stage III. The Cu/Au ratios in the Jiaojia pyrite in all mineralization stages were >1. These geochemical features imply that the ore-forming fluids of the Jiaojia gold deposit were in a medium- to low-temperature reducing environment, with temperatures gradually decreasing from ore Stages I to III. The increase in Co and As in the pyrite of Stage III implies that gold precipitation resulted from fluid immiscibility caused by a decrease in pressure and temperature and an increase in the oxygen fugacity of the ore-forming fluid. Full article

The Jiaodong Peninsula is renowned for its significant gold reserves, which exceed 4500 tons. In this study, we conducted zircon SHRIMP U-Pb dating, ⁴⁰Ar/³⁹Ar geochronology, electron probe microanalysis (EPMA) analysis, and He-Ar isotope analysis on samples from the Shuigou gold deposit located in the Qixia-Penglai-Fushan metallogenic area of central Jiaodong. This quartz vein-type gold deposit is characterized by three mineralization stages: (I) the quartz-pyrite stage, (II) the quartz-polymetallic sulfide stage, and (III) the calcite stage. In stages I and II, gold primarily exists as native gold or electrum. Preliminary analysis suggests that the deposit contains rare critical metals, including bismuth (Bi), tellurium (Te), and antimony (Sb). The Sb is found as pyrargyrite in stage III, while the other critical elements occur as isomorphisms or nanoparticles within host minerals such as pyrite, native gold, and electrum. Geochronology data indicate that the pre-mineralization Guojialing monzogranite formed around 126 ± 1.6 Ma, the syn-mineralization muscovite formed at approximately 125 Ma, and the post-mineralization diorite porphyrite formed at 120.4 ± 1.8 Ma. The ³He/⁴He ratios of fluid inclusions in the main-stage pyrite range from 0.26 to 1.26 Ra, and the ⁴⁰Ar/³⁶Ar ratios vary from 383 to 426.6. These findings suggest that the Shuigou gold deposit formed during the destruction of the North China Craton (NCC), similar to other super-large gold deposits in the Jiaodong Mesozoic gold metallogenic province. Gold mineralization has been influenced by mantle, crustal, and meteoric fluids. Full article

Delineating the process of hydrothermal alteration is crucial for effectively enhancing exploration strategies and better understanding the gold mineralization process. Rutile, with its capacity to accommodate a wide range of trace elements including high-field-strength elements and base metals, serves as a reliable fluid tracer in ore systems. As one of the most significant gold ore concentrations globally, Jiaodong boasts a gold reserve exceeding 5500 t. The Xincheng gold deposit is a world-class high-grade mine, boasting a proven gold reserve exceeding 200 t, and stands as one of the largest altered-type gold deposits in the vast gold province of the Jiaodong Peninsula, Eastern China. In this study, rutile (Rt1,2,3) was identified in the K-feldspar alteration, sericitization, and pyrite–sericite–quartz alteration stages of the Xincheng gold deposit in Jiaodong based on petrographic characteristics. Rt1 coexists with hydrothermal K-feldspar and quartz, while Rt2 coexists with minerals such as sericite, quartz, muscovite, and pyrite. Rt3 is widely distributed in hydrothermal veins and is primarily associated with minerals including quartz, pyrite, chalcopyrite, and sericite. Raman spectroscopy, EPMA, and LA-ICP-MS analysis were conducted to investigate the characteristics and evolution of altered hydrothermal fluids. This study indicates that the Zr vs. W and Nb/V vs. W diagrams suggest that Rt1 is of magmatic–hydrothermal origin, while Rt2 and Rt3 are of metamorphic–hydrothermal origin. Notably, the W content in Rt2 and Rt3 is significantly higher than in Rt1 (<100 ppm), suggesting a close relationship between the W content in rutile and mineralization. The three types of rutile exhibit significantly different concentrations of trace elements such as W, V, Nb, Zr, Sn, and Fe, displaying distinct bright spots and elemental zoning characteristics in backscattered electron images and surface scans. These features arise from the isomorphic substitution of Ti⁴⁺. While Rt1 exhibits no significant element exchange with the hydrothermal fluids, Rt2 and Rt3 show a stronger substitution of W, Nb, V, and Fe, indicating a gradual enrichment of F and Cl in the fluids. This process activates and transports these elements into the fluids, leading to their continuous accumulation within the system. From Rt1 to Rt3, the increasing concentrations of Fe and W, along with the negative Eu anomaly, suggest a decrease in fluid temperature and oxygen fugacity during the alteration and mineralization process. The gradual increase in the contents of REEs and high-field-strength elements such as W, V, Nb, and Sn indicates that the hydrothermal fluids are enriched in F and Cl, exhibiting weak acidity. The nature of the fluids during hydrothermal alteration is closely related to the composition of rutile, making it a promising tool for studying hydrothermal alteration and related mineralization processes. Full article

The Jiaodong gold province is one of the most important gold fields globally and the largest in China. The Denggezhuang gold deposit is situated in the eastern portion of the Muping metallogenic belt, within the Jiaodong gold province. Despite many recent investigations, detailed mineralogical studies, particularly on auriferous minerals such as pyrite, are lacking. Therefore, further constraints on the occurrence mode and source of gold are necessary for this deposit. This study employed in situ laser ablation (multi-collector) inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) trace element and sulfur-lead isotopic analyses on pyrite at different stages. The aim was to reveal the occurrence status of various trace elements within Denggezhuang pyrite and to trace the complete evolution process of multi-stage fluids at Denggezhuang, elucidating the sources of gold mineralization. Four generations of pyrite in chronological order, Py-1, Py-2a, Py-2b, and Py-3, were identified via petrographic and backscattered electron (BSE) image analyses. Using in situ LA-MC-ICP-MS, we found that Co and Ni are most abundant in Py-1, while Py-2b is rich in As, Au, Ag, Pb, and Zn, reflecting the evolution of the mineralizing fluids in different mineralization stages. Py-2b contains a significant amount of invisible lattice gold, which migrates and precipitates within fluids rich in As. The in situ LA-MC-ICP-MS S-Pb isotopic analysis of pyrite indicates a relatively consistent source of ore-forming materials across different stages. Additionally, the S-Pb isotope characteristics resemble those of widely distributed coeval mafic dikes. Therefore, we propose that a water-rich, fertile, and deep-seated mafic magmatic system might have provided fluids, materials, and heat for mineralization. Full article

The Fang’an quartz-vein gold deposit is located in the eastern part of the Bengbu uplift. The eastern part of the Bengbu uplift is considered to be the western extension of the Zhaoyuan gold mineralization zone in the Jiaodong area of Shandong Province and has huge mineralization potential. The Fang’an deposit was a newly discovered, small-sized gold deposit, and the research in the area is relatively weak. In this study, samples of quartz-vein type ore were collected from the ZK141, ZK1549, and ZK1665 drill holes of the Fang’an gold deposit. Based on the study of the geological characteristics, the major and trace elements of pyrite in different stages were analyzed by electron probe microanalyzer (EPMA), to explore the compositional characteristics of pyrite, the occurrence of gold, and the source of ore-forming fluid. The studies indicate that the deposit experienced four ore-forming stages: the quartz stage, the quartz-pyrite stage, the polymetallic sulfide stage, and the carbonate stage. The pyrites are grouped into three stages, corresponding to the first three ore-forming stages. The EPMA analyses showed that the major elements of pyrite were high Fe and low S, indicating that the formation was hydrothermal. The high content of Ni indicated that the metallogenic materials were derived from between the mantle and the lower crust. The general Co/Ni ratio of >1, with an average of 5.34, indicated that the ore-forming fluid was derived from the magmatic–hydrothermal fluid and wall rock. The Fang’an gold deposit mainly contains nano-gold. Full article

With the rapid depletion of mineral resources, deep prospecting is becoming a frontier field in international geological exploration. The prediction of deep mineral resources is the premise and foundation of deep prospecting. However, conventional metallogenic predictive methods, which are mainly based on surface geophysical, geochemical, and remote sensing data and geological information, are no longer suitable for deep metallogenic prediction due to the large burial depth of deep-seated deposits. Consequently, 3D metallogenic prediction becomes a critical method for delineating deep prospecting target areas. As a world-class giant gold metallogenic province, the Jiaodong Peninsula is at the forefront in China in terms of deep prospecting achievements and exploration depth. Therefore, it has unique conditions for 3D metallogenic prediction and plays an important exemplary role in promoting the development of global deep prospecting. This study briefly introduced the method, bases, and results of the 3D metallogenic prediction in the northwest Jiaodong Peninsula and then established 3D geological models of gold concentration areas in the northwest Jiaodong Peninsula using drilling combined with geophysics. Since gold deposits in the northwest Jiaodong Peninsula are often controlled by faulting in the 3D space, this study proposed a method for predicting deep prospecting target areas based on a stepped metallogenic model and a method for predicting the deep resource potential of gold deposits based on the shallow resources of ore-controlling faults. Multiple characteristic variables were extracted from the 3D geological models of the gold concentration areas, including the buffer zone and dip angle of faults, the changing rate of fault dip angle, and the equidistant distribution of orebodies. Using these characteristic variables, five deep prospecting target areas in the Jiaojia and Sanshandao faults were predicted. Moreover, based on the proven gold resources at an elevation of −2000 m and above, the total gold resources of the Sanshandao, Jiaojia, and Zhaoping ore-controlling faults at an elevation of −5000–−2000 m were predicted to be approximately 3377–6490 t of Au. Therefore, it is believed that the total gold resources in the Jiaodong Peninsula are expected to exceed 10,000 t. These new predicted results suggest that the northwest Jiaodong Peninsula has huge potential for the resources of deep gold deposits, laying the foundation for further deep prospecting. Full article

Controversy surrounds the genetic relationship between gold mineralization and magmatism, especially in deposits in granite. Jiaodong Peninsula is the leading gold province in China, and most deposits are in Mesozoic granites; moreover, debate on the genesis persists. In eastern Jiaodong, the Muping–Rushan gold belt produces mainly quartz–sulfide vein-type gold, and the Upper Jurassic Kunyushan granite and Late Lower Cretaceous Sanfoshan granite are the wall rock. Precise mineralization ages should be identified to determine whether gold is related to the intrusion. In this study, three gold deposits (Sanjia, Yinggezhuang, and Xipo) from two ore-controlling faults were considered. Muscovites from quartz–sulfide veins and beresite were selected for Argon–Argon dating. The results obtained were 116.51 ± 0.47 Ma, 120.02 ± 0.38 Ma, and 121.65 ± 0.48 Ma for the three deposits, respectively. The mineralization lasted about 5 Ma in the Muping–Rushan gold belt. The test results showed that the mineralization was 16 Ma later than the intrusion time of Kunyushan granite and was earlier than that of Sanfoshan granite. Only the cooling age overlapped with the mineralization age. Previous studies have demonstrated that the ore fluid is of medium–low salinity and medium–low temperature. No typical high–low temperature mineral assemblage exists in the Muping–Rushan gold belt. Hence, gold deposits in Muping–Rushan gold belt could not be categorized as intrusion-related gold type. Full article

The origin of ultramafic rocks, especially those in suture zones, has been a focus because they are not only important mantle sources of magma, but also provide substantial information on metamorphism and melt/fluid–peridotite interaction. Ultramafic rocks in Hujialin, in the central part of the Sulu orogen, include peridotite and pyroxenite. Although many papers on their origin and tectonic evolution have been published in the past few decades, these questions are still highly debated. Here, we present mineralogy, mineral composition, and bulk-rocks of these ultramafic rocks to evaluate their origin and tectonic evolution. The garnet clinopyroxenite is low in heavy rare-earth elements (HREE, 5.97–10.6 ppm) and has convex spoon-shaped chondrite-normalized REE patterns, suggesting the garnet formed later, and its precursor is clinopyroxenite. It is high in incompatible elements (i.e., Cs, Rb, Ba) and shows negative to positive U, Nb, and Ta anomalies, without pronounced positive Sr or Eu anomalies. Clinopyroxene in garnet clinopyroxenite contains high MgO (Mg^# 0.90–0.97). The mineral chemistry and bulk-rock compositions are similar to those of reactive clinopyroxenite, suggesting that it originally formed via peridotite–melt interaction, and that such silicic and calcic melt might derive from the subducted Yangtze continent (YZC). Dunite contains olivine with high Fo (93.0–94.1), low NiO (0.11–0.29 wt.%) and MnO (≤0.1 wt.%), chromite with high Cr^# (0.75–0.96), TiO₂ (up to 0.88 wt.%), and Na₂O (0.01–0.10 wt.%). It has negatively sloped chondrite-normalized REE patterns. Mineral chemistry and bulk rocks suggest dunite likely represent residual ancient lithosperic mantle peridotite beneath the North China Craton (NCC) that was overprinted by aqueous fluids. The lack of prograde and retrograde metamorphic minerals in dunite and irregular shaped mineral inclusions in chromite suggest dunite did not subduct to deep levels. Dunite mingled with garnet clinopyroxenite during exhumation of the latter at shallow depths. These ultramafic rocks, especially hydrated peridotite, may be important sources of Au for the Jiaodong gold province in the NCC. Full article

The Jiaodong gold mineral province, with an overall endowment estimated as >3000 t, located at the eastern segment of the North China Craton (NCC), ranks as the greatest source of Au in China. The structural evolution, magmatic activity and metallogenesis during the Mesozoic played important roles in the large scale regional gold, silver and polymetallic mineralization in this area; among them, the intensive activation of fault structures is the most important factor for metallogenesis. This study takes the regional deep faults as main thread to discuss the controlling role of faults in large scale metallogenesis. The Jiaojia fault and Sanshandao faults in the northwest margin of the Guojiadian mantle branch not only are dominant migration channels for hydrothermal fluid but are very important favorable spaces for ore-forming and ore-hosting during the formation of world-class super large gold deposits in this area. The deep metallogenic process can be summarized as involving intensive Earth’s core, mantle and crust activity → magmatism → uplifting of metamorphic complex → detachment of cover rocks → formation of mantle branch → penetration of hydrothermal fluid along deep faults → concentration of metallogenic materials → formation of super large deposits. Full article

The Jiaodong Peninsula in eastern China is the third largest gold-mining area and one of the most important orogenic gold provinces in the world. Ore shoots plunging in specific orientations are a ubiquitous feature of the Jiaodong lode deposits. The Sizhuang gold deposit, located in northwestern Jiaodong, is characterized by orebodies of different occurrences. The orientation of ore shoots has remained unresolved for a long time. In this paper, geostatistical tools were used to determine the plunge and structural control of ore shoots in the Sizhuang deposit. The ellipses determined by variogram modeling reveal the anisotropy of mineralization, plus the shape, size, and orientation of individual ore shoots. The long axes of the anisotropy ellipses trend NE or SEE and plunge 48° NE down the dip. However, individual ore shoots plunge almost perpendicular to the plunge of the ore deposit as a whole. This geometry is interpreted to have resulted from two periods of fluid flow parallel to two sets of striations that we identified on ore-controlling faults. Thrust-related lineations with a sinistral strike-slip component were associated with early-stage mineralization. This was overprinted by dextral and normal movement of the ore-controlling fault that controlled the late-stage mineralization. This kinematic switch caused a change in the upflow direction of ore-forming fluid, which in turn controlled the orientation of the large-scale orebodies and the subvertical plunge of individual ore shoots. Thus, a regional transition from NW-to-SE-trending compression to NW-to-SE-trending extension is interpreted as the geodynamic background of the ore-forming process. This research exemplifies an effective exploration strategy for studying the structural control of the geometry, orientation, and grade distribution of orebodies via the integration of geostatistical tools and structural analysis. Full article