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This study simulated the spatiotemporal changes in coastal ecosystem services (ESs) in the Jiaodong Peninsula from 2000 to 2050 and analyzed the driving mechanisms of climate change and human activities with respect to ESs, aiming to provide policy recommendations that promote regional sustainable development. Future climate change and land use were forecast based on scenarios from the Coupled Model Intercomparison Project Phase 6 (CMIP6). The Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model was used to assess ESs such as water yield (WY), carbon storage (CS), soil retention (SR), and habitat quality (HQ). Key drivers of ESs were identified using Structural Equation Modeling (SEM). Results demonstrate the following: (1) High WY services are concentrated in coastal built-up areas, while high CS, HQ, and SR services are mainly found in the mountainous and hilly regions with extensive forests and grasslands. (2) By 2050, CS and HQ will show a gradual degradation trend, while the annual variations in WY and SR are closely related to precipitation. Among the different scenarios, the most severe ES degradation occurs under the SSP5-8.5 scenario, while the SSP1-2.6 scenario shows relatively less degradation. (3) SEM analysis indicates that urbanization leads to continuous declines in CS and HQ, with human activities and topographic factors controlling the spatial distribution of the four ESs. Climate factors can directly influence WY and SR, and their impact on ESs is stronger in scenarios with higher human activity intensity than in those with lower human activity intensity. (4) Considering the combined effects of human activities and climate change on ESs, we recommend that future development decisions be made to rationally control the intensity of human activities and give greater consideration to the impact of climate factors on ESs in the context of climate change. [ABSTRACT FROM AUTHOR]

The Mesozoic intrusions of the Jiaodong Peninsula, eastern China, host giant gold deposits. Understanding the genesis of these deposits requires the determination of the source of the parental auriferous fluid and the timing of gold mineralization, which are strongly influenced by the cooling/uplift histories of the hosting intrusions. We performed an integrated U-Pb geochronology study on both zircon and apatite from four major magmatic episodes of the Jiaodong Peninsula. The zircon and apatite U-Pb ages are 156.9 ± 1.2 and 137.2 ± 2.4 Ma for the Linglong intrusion, 129.9 ± 1.0 and 125.0 ± 3.8 Ma for the Qujia intrusion, 119.5 ± 0.7 and 117.2 ± 1.8 Ma for the Liulinzhuang intrusion, 118.6 ± 1.0 and 111.6 ± 1.6 Ma for the Nansu intrusion, respectively. The coupled zircon and apatite data of these granitoids indicate a slow cooling rate (11.9 °C/Ma) in the Late Jurassic, and rapid uplift and cooling (35.8–29.2 °C/Ma) in the Early Cretaceous. The dramatically increased uplift and cooling period in the Early Cretaceous are contemporaneous with large-scale gold mineralization in the Jiaodong Peninsula. This implies that thermal upwelling of asthenosphere and related tectonic extension played an important role in gold remobilization and precipitation. [ABSTRACT FROM AUTHOR]

The Late Mesozoic lithospheric mantle evolution of the Jiaodong Peninsula is crucial for understanding the destruction of the eastern North China Craton (NCC) and large-scale gold mineralization, but it still remains highly controversial. Here, we comprehensively compiled published Late Mesozoic mafic dyke magmatism data from the Jiaodong Peninsula to provide key constraints on the nature and evolution of the lithospheric mantle. Mafic dykes are widely emplaced in the Jiaodong Peninsula and have been divided into two groups (Jiaobei terrane and Sulu orogenic belt); they mainly comprise lamprophyre, dolerite, and gabbro. The ages of the mafic dykes in the Jiaobei terrane are predominantly between 120 and 125 Ma, and those of the Sulu orogenic belt are between 110 and 120 Ma. The Jiaobei and Sulu mafic dykes both have high contents of Mg and compatible elements (Cr, Ni), as well as low SiO2 content; they are characterized by arc-like mafic magma, including enrichment in Large Ion Lithophile Elements and Light Rare Earth Elements, depletion in High Field Strength Elements, high (87Sr/86Sr)i, and low εNd(t), implying a metasomatized lithospheric mantle source. However, the Jiaobei mafic dykes have relatively higher (87Sr/86Sr)i, lower εNd(t), and a larger range of (206Pb/204Pb)i, (208Pb/204Pb)i, and (207Pb/204Pb)i compared with the Sulu mafic dykes. The Jiaobei and Sulu mafic dykes exhibit Ba/Rb ratios of 1.29‒64.39 (average 29.3) and 6.61‒108.28 (average 33.1), respectively, indicating the presence of hornblende in the melts. The high Fe/Mn (>60) and Zn/Fe (>12) ratios of Jiaobei and Sulu mafic dykes indicate the mixed mantle source of peridotite and pyroxenite. But the content of pyroxenite in the mantle source of Jiaobei terrane is higher with wider range of Fe/Mn and Zn/Fe ratios. These features indicate the heterogeneity of the mantle sources of the mafic dykes in the Jiaobei and Sulu regions. It is suggested that both regions originated from the partial melting of hornblende-bearing peridotite, with the addition of more pyroxenite to the mantle source of the Jiaobei terrane compared to Sulu orogenic belt. The mafic dykes have the low Nb/Zr (Jiaobei: 0.024–0.229; Sulu: 0.030–0.166) and Th/Zr ratios (Jiaobei: 0.017–0.081; Sulu: 0.010–0.068), and the high Rb/Y (Jiaobei: 0.347–12.162; Sulu: 0.224–9.600) and low Nb/Y ratios (Jiaobei: 0.202–1.486; Sulu: 0.140–1.322). It implies that the mantle source area in both regions was metasomatized by subducted slab-derived fluids. The increase in (La/Yb)N and decrease in Hf/Sm implies carbonate metasomatism in both regions. In addition, some Jiaobei and Sulu mafic dykes have high Ti/Eu ratios, implying that the silicate metasomatism occurred in the mantle source of both regions. Based on the regional evolution, the lithospheric mantle source in the two regions beneath Jiaodong Peninsula experienced carbonated fluid metasomatism resulting from the subduction of the Palaeo-Asian Ocean plate beneath the northern NCC (ca. ~250 Ma), silicate melt-related metasomatism from subduction of the Yangtze Craton plate beneath the southern NCC (ca. 240‒220 Ma), and oceanic slab-derived fluid metasomatism from the subducted Palaeo-Pacific plate (at 180‒110 Ma). It is believed that the mantle source of Jiaobei terrane had undergone stronger carbonated fluid metasomatism and silicate melt-related metasomatism, compared to Sulu orogenic belt. Moreover, the continental fluid-related metasomatism only occurred in the Sulu orogenic belt. During the Late Mesozoic, the eastern NCC experienced large-scale lithospheric thinning, leading to upwelling of the asthenospheric mantle. The mafic dykes in Jiaobei and Sulu, show different geochemical features, were derived from partial melting of the metasomatized lithospheric mantle through upwelling of the asthenospheric mantle. [ABSTRACT FROM AUTHOR]

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 206U-238Pb zircon age of 156 Ma, while the Shazibu pluton is a quartz monzonite, one sample of which records a 206U-238Pb zircon age of 117 Ma. The two plutons have variable zircon Hf-O isotopic compositions: zircon εHf(t) values of the Queshan pluton are −29.2 to −22.8, and δ18O values are 7.30–7.84 ‰, while the Shazibu pluton has relatively high zircon εHf(t) values (−21.6 to −21.0) and δ18O values of 7.48–8.43 ‰. 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°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. [ABSTRACT FROM AUTHOR]

To monitor the Ecological Environment Quality (EEQ) of the Jiaodong Peninsula and provide a scientific basis for ecological environment governance and sustainable development in the region, this study evaluates the EEQ of Jiaodong using the Remote Sensing-based Ecological Index (RSEI) model and analyzes its spatiotemporal evolution patterns, building upon single-factor correlation analysis using the Random Sample Consensus (RANSAC) algorithm, using GeoDetector to analyze the driving mechanisms of human activities and natural factors in EEQ. The results indicate the following: (1) The average RSEI values for 2000, 2010, and 2020 are 0.60, 0.57, and 0.66, with Good or Excellent areas accounting for 56.48%, 51.02%, and 67.17%. From 2000 to 2020, RSEI strong improvement areas were predominantly distributed in the eastern hilly areas of the Jiaodong Peninsula. The RSEI of the Jiaodong Peninsula showed significant spatial autocorrelation. (2) The RANSAC algorithm effectively reduces noise interference in remote sensing data, thereby improving the accuracy of single-factor correlation analysis. (3) In 2000, the importance of natural factors exceeds that of human activity factors. The Standardized Precipitation Evapotranspiration Index (SPEI) is the most important driving factor; while in 2010 and 2020, human activity factors surpass natural factors in importance, with the Land Use Composite Index (LUCI) being the most significant driving factor. The driving factors exhibited double-factor and nonlinear enhancement. The most significant interaction factors affecting the EEQ of the Jiaodong Peninsula in 2000, 2010, and 2020 are SPEI∩GDP, LUCI∩SPEI, and LUCI∩GDP. [ABSTRACT FROM AUTHOR]

This study simulated the spatiotemporal changes in coastal ecosystem services (ESs) in the Jiaodong Peninsula from 2000 to 2050 and analyzed the driving mechanisms of climate change and human activities with respect to ESs, aiming to provide policy recommendations that promote regional sustainable development. Future climate change and land use were forecast based on scenarios from the Coupled Model Intercomparison Project Phase 6 (CMIP6). The Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model was used to assess ESs such as water yield (WY), carbon storage (CS), soil retention (SR), and habitat quality (HQ). Key drivers of ESs were identified using Structural Equation Modeling (SEM). Results demonstrate the following: (1) High WY services are concentrated in coastal built-up areas, while high CS, HQ, and SR services are mainly found in the mountainous and hilly regions with extensive forests and grasslands. (2) By 2050, CS and HQ will show a gradual degradation trend, while the annual variations in WY and SR are closely related to precipitation. Among the different scenarios, the most severe ES degradation occurs under the SSP5-8.5 scenario, while the SSP1-2.6 scenario shows relatively less degradation. (3) SEM analysis indicates that urbanization leads to continuous declines in CS and HQ, with human activities and topographic factors controlling the spatial distribution of the four ESs. Climate factors can directly influence WY and SR, and their impact on ESs is stronger in scenarios with higher human activity intensity than in those with lower human activity intensity. (4) Considering the combined effects of human activities and climate change on ESs, we recommend that future development decisions be made to rationally control the intensity of human activities and give greater consideration to the impact of climate factors on ESs in the context of climate change.

[Display omitted] • Fluid-rock reaction modeling gives the optimal gold transport-deposition conditions. • The wallrock alteration progresses with synchronous gold enrichment amount is modeled. • A gold grade refinement by fracture-induced fluid flow and refocusing is predicted. The devolatilization model of the metasomatized lithospheric mantle without pre-enriched gold has been proposed to account for the giant gold mineralization. An excellent example is the world-class Jiaodong gold province with >5000 tonnes Au resources in the eastern North China Craton. The auriferous fluid transport and gold enrichment during wallrock alterations are two vital processes to determine the giant gold mineralization formation in this province. However, the effects of the fluid-rock interaction with alterations on the auriferous fluid transport and gold enrichment still keep poor understanding, which leads the above model to be imperfect. The giant Jiaojia goldfield in this province recorded a wallrock alteration evolution from K-feldspar alteration to pyrite-sericite-quartz alteration, and some parts of the latter can become gold orebodies when the gold grade is >1 ppm. This study conducts thermodynamic fluid-rock interaction modeling to reveal auriferous fluid transport and coupled relationship between gold enrichment and alteration mineral assemblage based on the alteration-mineralization and ore fluid characteristics of the goldfield. The modeling of fluid-rock interaction with cooling indicates the transformation of Au-Cl complexes to Au-S complexes combined with the total sulfur concentration decrease by pyrite precipitation when cooling from ∼460 °C can trigger the dispersive gold precipitation, which should hinder the gold long-range transport to lower ambient temperature. The high oxygen fugacity at >400 °C can enhance Au-Cl complexes stability, and the low pH can maintain high total sulfur concentration in the auriferous fluid, both of which facilitate the long-range gold transport to a lower-temperature environment. The auriferous fluid would acquire higher pH by the buffering of feldspars or sericite, which was beneficial for the high-efficiency precipitations of pyrite and gold. The ankerite-siderite assemblage without pyrophyllite in the pyrite-sericite-quartz alteration zone indicates that a cumulative fluid to rock mass ratio (f/r) of 3.8–4.8 should be needed for the transformation from K-feldspar alteration to pyrite-sericite-quartz alteration according to the fluid-rock interaction modeling at 300 °C and 2000 bar. In the case of auriferous fluids with ≤200 ppb Au concentration, the single fluid-rock interaction can only elevate the gold grade to ≤0.69–0.87 ppm in the pyrite-sericite-quartz alteration zone at f/r 3.8–4.8. Therefore, the fracture-induced fluid flow coupled with fluid-rock interaction is proposed to the prerequisite to elevate the gold grade to >1 ppm in the pyrite-sericite-quartz alteration zone. The metasomatized lithospheric mantle volume for the required ore fluid and Au in the Jiaodong province is estimated according to the modeling results and alteration-mineralization characteristics, which provides a link between the mantle without abnormal Au enrichment and the alteration-mineralization processes. [ABSTRACT FROM AUTHOR]

Finding new, effective predictive variables for 3D mineral prospectivity modeling is both important and challenging. The 3D ore-forming numerical modeling quantitively characterizes the complex coupling-mineralization process of the structure, fluid, heat, and wall rock, which may be potential indicators for mineral exploration. We here conducted 3D mineral prospectivity modeling with the integration of ore-forming computational simulation information in the Xiadian orogenic gold deposit, China, to examine whether the simulation data input can improve the reliability of prospectivity modeling. First, we constructed the 3D models of the orebody and fault to extract the fault geometric features using spatial analysis, as they are always considered to be the crucial controls of gold distribution. Second, we performed 3D numerical modeling of the deformation–fluid–heat-coupling process of the structurally controlled hydrothermal Au system using the FLAC3D platform. Finally, the fault-geometry features (buffer, dip, dip variation, and undulation) and the ore-formation-simulation indices (volume strain, shear strain, temperature variation, and fluid flux) were integrated using Bayesian decomposition modeling, which has a promising nonlinear model ability and a flexible variable-integration ability. The prospectivity modeling results demonstrated that the model generated by combining geometry and simulation variables achieved significantly higher AUC, precision, accuracy, Kappa, and F1 scores compared to other models using a single-predictor-variable dataset. This suggests that the joint use of geometry and simulation variables construct a comprehensive association between gold and its ore-controlling factors, thereby resulting in a highly reliable prospectivity model. Thus, the approach of 3D mineral prospectivity modeling aided by ore-forming numerical simulation proves to be more useful in guiding mineral exploration, especially in the condition of fewer variables. Based on the prospectivity modeling outcomes, we identified four gold targets at depth in the Xiadian district that warrant focused exploration efforts. [ABSTRACT FROM AUTHOR]

The Jiaodong Peninsula is closely related to Mesozoic granites in terms of spatial and temporal aspects. However, the specific association between the genesis of gold mineralization and these granites remains unclear. It is also ambiguous why Laoshan-type granites, which are similar to Mesozoic granites, are not gold mineralized. In this study, we analyzed the Laoshan granites and compiled Mesozoic magmatic rock data (Linglong, Guojialing, and Weideshan suites) of the Jiaodong Peninsula. We performed whole-rock major and trace elements, LA–ICP–MS zircon U–Pb geochronology and geochemistry analyses. Our zircon U–Pb data denote that the Laoshan granite was emplaced during the 118 ± 1 Ma. The Laoshan granite is characterized by high SiO2 content (76.03–80.28 wt.%), high TFe2O3/MgO (11.1–27.1) and Ga/Al (3.0–3.5) ratios, high zircon saturation temperature (809–850 °C), and negative Eu (Eu/Eu* = 0.05–0.08) anomalies, showing A-type granite characteristics. Furthermore, the Laoshan granite is identified as an A1-type granite with low Ba (33.1–42.0 ppm) and Sr (14.1–21.0 ppm) contents. It was formed in an extensional tectonic environment induced by the subducting slab roll-back of the Paleo-Pacific Plate, mainly from the partial melting of lower crustal materials, mixed with a small amount of mantle components. Zircon trace elements indicate that the Laoshan suite had relatively high oxygen fugacity and temperature (ΔFMQ = + 2.43 to + 4.22, T-Ti in zircon (mean) = 796 °C) compared to the pre-mineralization and contemporaneous mineralization magma. We propose that oxidized adakitic magma (Weideshan suite) may contribute to the enrichment and mineralization of gold. Although Laoshan-type granite also has a high oxygen fugacity, its location is distant from the ore-controlling faults, which ultimately hinders the formation of gold mineralization. From the Jurassic to the Cretaceous, the tectonic and geochemical properties of magmatic rocks in the Jiaodong Peninsula have changed, and gold deposits are formed in such a transitional process (compression to extension, reduction to oxidation). [ABSTRACT FROM AUTHOR]

Many young women were believed to die due to pregnancy and childbirth in the past, yet few cases of pregnant female burials have been reported in bioarcheological literature. Therefore, this paper reports the burial of an adult female (H49‐1) and her infant (H49‐2), who were buried together in an early Western Zhou pit at the Sanbulijia site, Jiaodong Peninsula, Shandong Province, China. It is the first reported case of obstetric death in thePre‐Qin Period in Shandong Province. The mother–child relationship was proved by ancient DNA evidence and archeological context. The infant's remains were placed between the adult's lower legs. Skeletal histological evidence suggests that the infant died during or shortly after childbirth. Sacroiliac fusion of individual H49‐1 may have resulted in dystocia. Furthermore, a special postmortem burial ritual—pit burial, was carried out for both the infant and the mother. H49 is the first Zhou Dynasty pit burial (multiple burial) with an exact radiocarbon date in the Shandong Peninsula. The case under review suggests that both the adult and the infant may have died due to special events, which may be related to obstetric death. [ABSTRACT FROM AUTHOR]

Element geochemistry, Sr and Nd isotope, and LA-ICP-MS zircon U-Pb isotope data have been obtained for the granitoids of Dazesan pluton in the Jiaodong Peninsula, East China, and their intermediate microgranular dark enclaves so as to reveal their petrogenesis and tectonic implications. These granitoids have high SiO2 (68.25–71.56 wt.%), K2O (3.44–5.50 wt.%), total alkalis (K2O + Na2O = 7.29–9.00 wt.%), Sr (451–638 ppm), Ba (1157–2842 ppm) and light rare earth elements (LREEs) (131.57–210.08), with strong depletion both in heavy rare earth element (HREE) and high field strength element (HFSE) concentrations as well as unclearly Eu anomalies, showing typical signatures of high Ba-Sr granitoids. They possess high (La/Yb)N (32–50) and Sr/Y (50–79) values and low MgO (0.76–1.11 wt.%), Cr (9.9–19.6 ppm) and Ni (4.51–7.04 ppm) concentrations. All the above geochemical compositions are similar to those of late Early Cretaceous granitoids, in combination with zircon LA-ICP-MS U-Pb ages of 119.6 ± 1.3 to 120 ± 1 Ma for these granitoids obtained in this study, indicating c. 120 Ma probably represents the lower limit of ages when late Early Cretaceous granitoids emplaced in the Jiaodong Peninsula. The microgranular dark enclaves, forming a linear trend with their host granitoids on the oxide against SiO2 plots, display higher MgO contents of 3.05–4.39 wt.% at lower SiO2 concentrations of 54.25–56.84 wt.% and possess a zircon LA-ICP-MS U-Pb age of 119 ± 2 Ma, identical to those of these granitoids, indicating the acid magma and intermediate magma were coeval. Furthermore, dark enclaves and their host granitoids have indistinguishable (87Sr/86Sr)i values of 0.709523–0.70972 and 0.709361–0.709858, respectively, and plot within a two-liquid immiscible field on the Greig pseudoternary phase diagram. In addition, they have markedly parallel REE patterns, with the dark enclaves having much greater REE and HFSE abundances than those of their host granitoids. Therefore, it is suggested that liquid immiscibility is a viable model to explain the chemical compositional variations between the Dazeshan granitoids and their dark enclaves. Based on the element geochemistry, geochronology and Sr- and Nd-isotope of the Dazeshan granitoids and their dark enclaves, it is envisaged the crust-derived acid melts due to partial melting of ancient continental lower crust in the Jiaodong Peninsula (mainly Neoarchean-Palaeoproterozoic basement in the Jiaobei terrane) containing a subduction-related material, resulting from the addition of the enriched subcontinental lithospheric mantle-derived melts, assimilated the lithospheric mantle-derived basic melts and formed the homogeneous magma chamber at the crust base, then split into two immiscible liquids, with one granitic liquid producing the Dazeshan granitoids and the other intermediate one forming the dark enclave during its ascent. Combined with previous studies, the identification of a lithospheric mantle-derived material in the Dazeshan granitoids suggests a catastrophic lithospheric thinning at c. 120 Ma, reflecting an abrupt change in the direction of Palaeo-Pacific plate subducting and the corresponding regional tectonic transition from E–W extension to NW–SE extension. [ABSTRACT FROM AUTHOR]

[Display omitted] • OPLS-DA analysis of mineral SWIR spectral data can distinguish wall-rock samples and ore samples. • RF analysis on white micas spectral data can effectively distinguish orebodies. • Machine learning integrated with SWIR analysis can effectively guide the exploration of lode gold deposits. 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 gold-sulfide (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. [ABSTRACT FROM AUTHOR]

Finding new, effective predictive variables for 3D mineral prospectivity modeling is both important and challenging. The 3D ore-forming numerical modeling quantitively characterizes the complex coupling-mineralization process of the structure, fluid, heat, and wall rock, which may be potential indicators for mineral exploration. We here conducted 3D mineral prospectivity modeling with the integration of ore-forming computational simulation information in the Xiadian orogenic gold deposit, China, to examine whether the simulation data input can improve the reliability of prospectivity modeling. First, we constructed the 3D models of the orebody and fault to extract the fault geometric features using spatial analysis, as they are always considered to be the crucial controls of gold distribution. Second, we performed 3D numerical modeling of the deformation–fluid–heat-coupling process of the structurally controlled hydrothermal Au system using the FLAC3D platform. Finally, the fault-geometry features (buffer, dip, dip variation, and undulation) and the ore-formation-simulation indices (volume strain, shear strain, temperature variation, and fluid flux) were integrated using Bayesian decomposition modeling, which has a promising nonlinear model ability and a flexible variable-integration ability. The prospectivity modeling results demonstrated that the model generated by combining geometry and simulation variables achieved significantly higher AUC, precision, accuracy, Kappa, and F1 scores compared to other models using a single-predictor-variable dataset. This suggests that the joint use of geometry and simulation variables construct a comprehensive association between gold and its ore-controlling factors, thereby resulting in a highly reliable prospectivity model. Thus, the approach of 3D mineral prospectivity modeling aided by ore-forming numerical simulation proves to be more useful in guiding mineral exploration, especially in the condition of fewer variables. Based on the prospectivity modeling outcomes, we identified four gold targets at depth in the Xiadian district that warrant focused exploration efforts.

Located in the Penglai-Qixia-Fushan Gold Belt, the Yangjiakuang gold deposit formed in the marble of the Paleoproterozoic Fenzishan Group is different from the previous altered rock-type gold deposits whose host gold-bearing rocks are Archean gneiss and Mesozoic granite. Two gold orebodies have been explored within the Yangjiakuang gold deposit, and both of them were controlled by the Yangjiakuang syncline. Three ore-forming stages have been recognized, including the pyrite-sericite stage (I), the gold, polymetallic sulfide, and quartz stage (II), and quartz-calcite stage (III). The calcites, which represent the main metallogenic stage (II) at Yangjiakuang gold deposit, yielded a Sm-Nd isochron age of 123.5 ± 8.1 Ma (MSWD = 0.042). Subsequent geologic events were recorded by quartz diorite porphyrite dyke which are dated at 122.75 ± 0.66 Ma (MSWD = 1.5) by zircon LA-ICP-MS U-Pb dating. It is suggested that the gold mineralization took place in the early period of Early Cretaceous. The in situ δ34S values of pyrites from two stages have a narrow range from + 5.65 to + 9.63‰ with an average value of 8.14‰, which indicate that the source of δ34S is related to the Guojialing granite and the Fenzishan Group. The lead isotopic compositions of pyrites (206Pb/204Pb = 16.615 to 16.832; 207Pb/204Pb = 15.275 to 15.403; 208Pb/204Pb = 36.829–37.470) show a consistent origin of the lower crust. The measured 3He/4He (40Ar/36Ar) of hydrothermal fluids in pyrites are 0.641–1.132 Ra (637.5–1162.7), indicating that the ore-forming fluid originating from a mixing of crustal and mantle components. It is suggested that the gold mineralization is associated with extensional tectonic inversion caused by the rollback of the subducting Izanagi Plate during the early Cretaceous, which triggered partial melting of mantle and lower crust, and subsequent magma mixing and exsolution of ore-bearing fluids. These fluids extracted ore-forming materials from the enclosing rocks of the Jiaodong Group, the Fenzishan Group, and the Guojialing granite to form the ore-forming fluids.

Mafic microgranular enclaves (MMEs) are hosted by the Early Cretaceous granitic plutons from the Jiaodong Peninsula and are crucial for constraining the petrogenesis of these plutons and understanding the lithospheric evolution in the eastern North China Craton (NCC). This paper presents new geochronological, bulk-rock geochemistry, and Sr-Nd-Hf isotope data for Yashan granodiorite and its MMEs in an effort to build an integrated model of the geodynamic setting during the Early Cretaceous. Zircon U–Pb dating indicates that Yashan granodiorite (116 ± 0.42 Ma) is coeval with its MMEs (117 ± 0.81 Ma). The MMEs display magmatic textures and disequilibrium textures such as acicular apatites, plagioclase with reverse zoning, and overgrowth of amphibole around pyroxene, indicating magma mingling/mixing. The SiO2 (55.64–59.9 wt.%), MgO (3.34–5.25 wt.%), Cr (74–245 ppm), and Ni (24–91.2 ppm) contents of the Yashan MMEs combined with their Sr-Nd-Hf compositions that are identical to local arc-like mafic dikes suggest that their primary magma derived from partial melting of a metasomatised lithospheric mantle. Yashan granodiorite is characterized by relatively high SiO2 (66.93–67.63 wt.%) and low MgO (1.66–1.67 wt.%) contents, I-type, high-K calc-alkaline, metaluminous affinities, and corresponding Hf model ages from Neoarchean-Paleoproterozoic, which indicate that the felsic magma was derived from partial melting of ancient NCC lower continental crust. Our data combined with previous studies on Early Cretaceous MMEs and host granites in the Jiaodong Peninsula indicate that the Cretaceous magmatism is the result of rollback of the subducting Paleo-Pacific plate beneath the eastern NCC. Asthenospheric mantle convection generated by slab rollback induced the thinning of the lithosphere and provided necessary heat to cause partial melting of the lithospheric mantle and overlying lower crust, followed by crustal-mantle interaction. The emplacement of Yashan granodiorite and other Weideshan granites and hosted MMEs indicates the peak of lithospheric thinning. [ABSTRACT FROM AUTHOR]

The intrusive age ranges of Linglong, Guojialing, Weideshan, and Laoshan granites in the Jiaodong Peninsula are 155–154 Ma, 131–130 Ma, 118–111 Ma, and 116 Ma, respectively. Together with the Shidao granite (227–200 Ma), five phases of magmatism can be classified by the time, all of which have different degrees of gold and polymetallic mineralization. The type of granites evolved from A–, S–type to I–, A–type from the Late Triassic to the Early Cretaceous, thus reflects the evolution of geodynamics in the Mesozoic, indicating the switch from North China Craton (NCC)–Yangtze Craton (YC) collision to subduction of the Paleo–Pacific Plate (PPP), with crustal thickening switching to lithospheric thinning and a compressional tectonic setting changing to an extensional setting. It directly leads to a series of extensional structures evolving in the Jiaodong Peninsula and demonstrates affinity for the extensive mineralization in the Early Cretaceous. The key markers of Jiaodong gold and polymetallic mineralization are magmatism, fluid activity and extensional structure. Extensive magmatic uplift and extensional structures in the Early Cretaceous formed the extensional tectonic system. During the formation process, a large proportion of crust and mantle materials exchanged and mixed, and the fluid interaction was highly active, resulting in a magmatic fluid metallogenic system, which provided favorable metallogenic conditions for gold and nonferrous metal hydrothermal deposits. Thus, a large-scale explosive mineralization occurred in Jiaodong in the middle and late Early Cretaceous. [ABSTRACT FROM AUTHOR]

The Jiaodong Peninsula is closely related to Mesozoic granites in terms of spatial and temporal aspects. However, the specific association between the genesis of gold mineralization and these granites remains unclear. It is also ambiguous why Laoshan-type granites, which are similar to Mesozoic granites, are not gold mineralized. In this study, we analyzed the Laoshan granites and compiled Mesozoic magmatic rock data (Linglong, Guojialing, and Weideshan suites) of the Jiaodong Peninsula. We performed whole-rock major and trace elements, LA–ICP–MS zircon U–Pb geochronology and geochemistry analyses. Our zircon U–Pb data denote that the Laoshan granite was emplaced during the 118 ± 1 Ma. The Laoshan granite is characterized by high SiO2 content (76.03–80.28 wt.%), high TFe2O3/MgO (11.1–27.1) and Ga/Al (3.0–3.5) ratios, high zircon saturation temperature (809–850 °C), and negative Eu (Eu/Eu* = 0.05–0.08) anomalies, showing A-type granite characteristics. Furthermore, the Laoshan granite is identified as an A1-type granite with low Ba (33.1–42.0 ppm) and Sr (14.1–21.0 ppm) contents. It was formed in an extensional tectonic environment induced by the subducting slab roll-back of the Paleo-Pacific Plate, mainly from the partial melting of lower crustal materials, mixed with a small amount of mantle components. Zircon trace elements indicate that the Laoshan suite had relatively high oxygen fugacity and temperature (ΔFMQ = + 2.43 to + 4.22, T-Ti in zircon (mean) = 796 °C) compared to the pre-mineralization and contemporaneous mineralization magma. We propose that oxidized adakitic magma (Weideshan suite) may contribute to the enrichment and mineralization of gold. Although Laoshan-type granite also has a high oxygen fugacity, its location is distant from the ore-controlling faults, which ultimately hinders the formation of gold mineralization. From the Jurassic to the Cretaceous, the tectonic and geochemical properties of magmatic rocks in the Jiaodong Peninsula have changed, and gold deposits are formed in such a transitional process (compression to extension, reduction to oxidation).

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. [ABSTRACT FROM AUTHOR]

The Xiawolong gold deposit, located in the Muping–Rushan gold metallogenic belt (eastern Jiaodong Peninsula), is a newly discovered deposit that developed in the late Early Cretaceous as fine-grained granite. Gold mineralization, which mainly occurs in the middle of fresh fine-grained granite dikes, consists of stockwork-style and disseminated ores. They are characterized by middle-high-temperature mineral assemblages, such as molybdenite and magnetite, associated with gold-bearing pyrite. Four types of primary fluid inclusions, contained within the quartz grains from the gold-bearing disseminated and stockwork-style fine-grained granitic ores, were identified based on microthermometry and Raman spectroscopy. The types identified were type 1 aqueous inclusions with middle-high temperature (201 to 480 °C) and middle-low salinity of 0.18 to 17.00 wt.% NaCl equiv.; type 2 H2O–CO2 inclusions, which show middle-high temperatures (218 to 385 °C), middle-low salinities (1.23 to 13.26 wt.% equiv. NaCl), and variable XCO2 (0.031 to 0.044); type 3 daughter mineral-bearing inclusions with high temperature (416 to 446 °C) and relatively constant and high salinity (28.59 to 32.87 wt.% NaCl equiv.); and type 4 CO2 fluid inclusions, which possess a bulk density of 0.405 to 0.758 g/cm3 and a constant XCO2 (0.952 to 0.990) (according to the decreasing abundance of fluid inclusions). The δ18Owater range is between 3.4 and 5.9‰, and the range of the δD is from −97.1 to −77.4‰, which indicates that the ore-forming process is of a magmatic water origin. The δ34S values possess a narrow range between 4.5 and 9.3‰, indicating the source of the Mesozoic Kunyushan granitoids. The Pb isotopic compositions of pyrite show that the Mesozoic Kunyushan granitoids are the main lead source for pyrites. Types 1, 2, and 3 fluid inclusions coexist in the same view field of the quartz grain, which are suggested to occur as the result of fluid immiscibility because of the boiling of a single homogeneous NaCl-CaCl2-KCl-CO2-H2O system. The fluid immiscibility, rather the fluid mixing and wall-rock sulfidation, is the mechanism of gold precipitation in the Xiawolong deposit. Compared with both the "Linglong-type" and "Jiaojia-type" gold deposits in the Jiaodong Peninsula in terms of geological–petrographic evidence and all of the available geochemical data, it can be concluded the Xiawolong gold deposit is of magmatic hydrothermal origin, having a genetic relation to the fine-grained granite. [ABSTRACT FROM AUTHOR]

[Display omitted] • Intermediate–mafic dyke swarms in Jiaodong peninsula are dated (122–121 Ma). • The dykes were formed in a WNW-ESE oriented extensional stress field. • Tectono-magmatic processes at crust–mantle depths were decoupled along the Moho. • Destruction of the lithospheric keel in southeastern NCC occurred at 122–120 Ma. • Tectonic extension acted as the major driving force for destruction of the craton. The coupling/decoupling relationships between shallow crustal deformation and deep mantle tectono-magmatic activities, during lithospheric thinning and destruction of cratons, remain hotly debated in the last decades. Multidisciplinary studies were done on intermediate–mafic dyke swarms diffusively located in southern Jiaodong peninsula, southeastern North China craton (NCC) to explore the crustal and lithospheric mantle responses to regional tectonic extension. Uniform ages (122–121 Ma) of the dykes indicate intensive magma generation at the mantle depth around 122 Ma related to large-scale tectonic extension of regional lithospheric mantle. Systemic anisotropy of magnetic susceptibility (AMS), geochemical, and Sr-Nd isotope analyses suggest that the dykes were originated from enriched lithospheric mantle sources and emplaced along crustal fractures formed in a WNW-ESE oriented extensional stress field. We show that the Jiaodong lithosphere experienced two stages of Early Cretaceous tectonic evolution, i.e., an early stage (135–122 Ma) lithospheric thinning characterized by large-scale tectonic extension of the crust and limited magmatic activities of crustal sources, and a late stage (122–108 Ma) lithospheric root collapse dominated by intensive tectonic extension and magmatism in the lithospheric mantle level. The decoupling crust-mantle evolution during lithospheric thinning and destruction of the NCC is ascribed to continuous tectonic extension in WNW-ESE direction. [ABSTRACT FROM AUTHOR]

The origin of the Mesozoic high Ba-Sr (HBS) granitic magmatism in the Jiaodong Peninsula remains controversial in petrogenesis models and geodynamic settings. Here, we report zircon U-Pb age, trace element and oxygen isotope compositions, and whole-rock major-trace element and Sr-Nd isotope compositions of the HBS Yashan granodiorite. The zircon U-Pb age of ∼118 Ma denotes that the Yashan granodiorite belongs to the Weideshan-stage magmatic activity, which is consistent with the age of Mo mineralization in the Yashan intrusion. The low Sr/Y (48.8–115) and high (La/Yb)N (23.8–50.4) ratios of the Yashan granodiorite are analogous to adakitic features derived from the lower-crust. This is also supported by the whole-rock initial 87Sr/86Sr ratios (0.709 6–0.710 3) and zircon δ8O values (6.79‰–8.03‰). Contemporaneous mantle-derived mafic microgranular enclaves indicate the involvement of the metasomatized lithospheric mantle. The high magma oxygen fugacity of the Yashan intrusion as indicated by high zircon Ce4+/Ce3+ values suggests the involvement of plate subduction. The obviously lower Dy/Yb, La/Yb and Sr/Y ratios of magmatic rocks in the Weideshan-stage than those in the early-stage imply lithospheric thinning of the eastern North China Craton. We propose that the Yashan HBS granodiorite was formed by crust-mantle interactions during slab rollback. [ABSTRACT FROM AUTHOR]

Bohai Bay Basin, located in the North China Craton, are surrounded by the Yanshan Mountains to the north, the Taihang Mountains to the west, the Jiaodong and Liaodong peninsulas to the south and east, respectively. The Yellow River, combined with the Liaohe, Luanhe and Haihe rivers, produces a huge amount of detrital sediments to the Bohai Bay Basin each year. However, it has not been clear whether the sediments have been transported to the Bohai Sea and the gulf of Jiaodong Peninsula. In addition, there is no definite result suggesting that these sediments are related to the provenance in the gulf of Jiaodong Peninsula. Zircon and apatite are common accessory minerals in the river sediments. The zircon U-Pb age and the in-situ geochemical data of apatite grains show significant differences in different regions, making them the ideal minerals for the provenance study. In this case, we used the published detrital zircon U-Pb ages from the major inflow rivers of the Bohai Bay Basin, combining with the drilling cores zircon U-Pb ages and integrating with the multi-dimensional identification (MDS) of kolmogorov-smirnov statistical method, to systematically identify the potential source areas in the Liaodong Bay, Bohai Central Basin and Laizhou Bay. The results show that the detrital sediments in the Liaodong Bay mainly came from the Liaohe River, while that in the Bohai Central Basin and Laizhou Bay from the Yellow River. The Yellow River plays a major role in the material composition of the central and western parts of the Bohai Sea. At the same time, we carried out the laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) on the detrital apatite grains from the lower reaches of the Yellow River (n=70), and the Weihai Bay (n=120) and Yintan Bay (n=60) from the Jiaodong Peninsula. The results show that there is no provenance relationship between them. Combined with the in-situ geochemical analysis results of detrital K-feldspar in this area, it further indicates that there is no provenance relationship between the Yellow River and the gulf of Jiaodong Peninsula. Therefore, the combination of in-situ geochemical analysis of detrital zircon and apatite helps to accurately determine the provenance relationship.

Late Mesozoic granites are present throughout the Jiaodong Peninsula in eastern China, but the petrogenesis of these granites, the magma sources, and the geodynamic setting of the magmatism remain unclear. This paper presents new zircon U–Pb geochronological and Lu–Hf isotopic and whole‐rock geochemical data for the Late Jurassic Queshan pluton in the Shandong Peninsula, an area that represents the boundary between the Jiaobei and Sulu ultrahigh‐pressure (UHP) terranes. Laser ablation–inductively coupled plasma–mass spectrometry zircon U–Pb dating yields Late Jurassic ages from 158 ± 1 to 153 ± 1 Ma for the pluton in addition to a small number of inherited zircons that yield ages that cluster at 2410, 1831–1776, 750, and 209–202 Ma. Zircons from different samples have similar 176Hf/177Hf values (0.281926–0.282255) and variably negative εHf (t) values that range from −26.5 to −15.1 (weighted mean of −22.9 ± 0.9). The corresponding two‐stage Hf model ages range from 2,869 to 2,154 Ma, with a weighted mean value of 2,645 ± 54 Ma. These data indicate that the magmas that formed the Queshan pluton were derived from multiple sources, including the lower crust of the North China (NCC) and Yangtze (YC) cratons, as well as collision‐related alkaline rocks. The whole‐rock geochemical compositions of the samples indicate that the granites are weakly peraluminous, are high‐K and calc‐alkaline with I‐type affinities, and have high contents of Sr, low contents of Y and Yb, high (La/Yb)N and Sr/Y values, and positive Eu anomalies (δEu = 1.20–1.65), indicating an adakitic affinity. This indicates that the Queshan granites formed from magmas generated by partial melting of a thickened region of the crust (>50 km) associated with eclogite, garnet amphibolite, or amphibolite residual material. The genesis of the Late Jurassic granites are also likely to have been influenced by the collisional orogeny between the NCC and YC and continued subduction of the Izanagi Plate. Thickening of the lower crust associated with this continental collisional event occurred before the magmatism, with further compression and thickening of the lower crust caused by the low‐angle subduction of the Izanagi Plate beneath northeastern China being the main geodynamic driver of the formation of the granites in this region. [ABSTRACT FROM AUTHOR]

Previous studies have shown that on the surface, Jiaobei uplift and Weihai uplift have higher heat flow values than Jiaolai depression. However, the mechanism by which the deep heat flow migrates and the exposure of geothermal resources are still unclear. In this study, the geothermal field distribution, thermal conductivity, temperature logging data, and chemical composition of the geothermal fluid in the Jiaodong Peninsula were analyzed. Regarding the thermal field’s characteristics and their controlling factors, a conceptual model of heat flow diversion-accumulation between the uplift and basin areas in the Jiaodong Peninsula is proposed. The lithology of the uplift area is mainly composed of intrusive rocks and metamorphic rocks with high thermal conductivities. The lithology of the basin mainly consists of sandstone with a low thermal conductivity. The bottom of the basin, which has a low thermal conductivity and low permeability, serves as a heat insulation and water insulation roof, which causes the heat flow and the heat-carrying fluids and gases from the deep crust to be refracted and redistributed at the bottom of the basin area. As a result, the bottom of the uplift areas has a higher heat flow. In particular, the axial position in the uplift area has the highest heat flow. In addition, the geothermal resources in the Jiaodong Peninsula are mainly distributed in the V-shaped area where the upper block of the NE- and NW-trending faults intersect, and the scope of the exposure of the geothermal resources is very limited.

Element geochemistry, Sr and Nd isotope, and LA-ICP-MS zircon U-Pb isotope data have been obtained for the granitoids of Dazesan pluton in the Jiaodong Peninsula, East China, and their intermediate microgranular dark enclaves so as to reveal their petrogenesis and tectonic implications. These granitoids have high SiO2 (68.25–71.56 wt.%), K2O (3.44–5.50 wt.%), total alkalis (K2O + Na2O = 7.29–9.00 wt.%), Sr (451–638 ppm), Ba (1157–2842 ppm) and light rare earth elements (LREEs) (131.57–210.08), with strong depletion both in heavy rare earth element (HREE) and high field strength element (HFSE) concentrations as well as unclearly Eu anomalies, showing typical signatures of high Ba-Sr granitoids. They possess high (La/Yb)N (32–50) and Sr/Y (50–79) values and low MgO (0.76–1.11 wt.%), Cr (9.9–19.6 ppm) and Ni (4.51–7.04 ppm) concentrations. All the above geochemical compositions are similar to those of late Early Cretaceous granitoids, in combination with zircon LA-ICP-MS U-Pb ages of 119.6 ± 1.3 to 120 ± 1 Ma for these granitoids obtained in this study, indicating c. 120 Ma probably represents the lower limit of ages when late Early Cretaceous granitoids emplaced in the Jiaodong Peninsula. The microgranular dark enclaves, forming a linear trend with their host granitoids on the oxide against SiO2 plots, display higher MgO contents of 3.05–4.39 wt.% at lower SiO2 concentrations of 54.25–56.84 wt.% and possess a zircon LA-ICP-MS U-Pb age of 119 ± 2 Ma, identical to those of these granitoids, indicating the acid magma and intermediate magma were coeval. Furthermore, dark enclaves and their host granitoids have indistinguishable (87Sr/86Sr)i values of 0.709523–0.70972 and 0.709361–0.709858, respectively, and plot within a two-liquid immiscible field on the Greig pseudoternary phase diagram. In addition, they have markedly parallel REE patterns, with the dark enclaves having much greater REE and HFSE abundances than those of their host granitoids. Therefore, it is suggested that liquid immiscibility is a viable model to explain the chemical compositional variations between the Dazeshan granitoids and their dark enclaves. Based on the element geochemistry, geochronology and Sr- and Nd-isotope of the Dazeshan granitoids and their dark enclaves, it is envisaged the crust-derived acid melts due to partial melting of ancient continental lower crust in the Jiaodong Peninsula (mainly Neoarchean-Palaeoproterozoic basement in the Jiaobei terrane) containing a subduction-related material, resulting from the addition of the enriched subcontinental lithospheric mantle-derived melts, assimilated the lithospheric mantle-derived basic melts and formed the homogeneous magma chamber at the crust base, then split into two immiscible liquids, with one granitic liquid producing the Dazeshan granitoids and the other intermediate one forming the dark enclave during its ascent. Combined with previous studies, the identification of a lithospheric mantle-derived material in the Dazeshan granitoids suggests a catastrophic lithospheric thinning at c. 120 Ma, reflecting an abrupt change in the direction of Palaeo-Pacific plate subducting and the corresponding regional tectonic transition from E–W extension to NW–SE extension.

Mafic lava is generally used to study the oxygen fugacity of lithospheric mantle. However, some studies confirmed that the high oxygen fugacity of mafic lava from lithospheric mantle may be result of auto-oxidation during the late magma evolution. Whether mafic lava reflects the oxygen fugacity of source area remains controversial. The major and trace element compositions of biotite, amphibole, and plagioclase as well as the Sr isotopes of plagioclase were in-situ examined aim to evaluate the variation in oxygen fugacity of mafic magma during transportation from depth to current location. Mineralogical characteristics show that the dikes originate from an enriched lithospheric mantle source and experienced very little or no crustal contamination during the magma transfer process. Clinopyroxene, plagioclase, Al-rich amphibole, biotite, and Mg-rich amphibole crystallized successively as the depth of magma reduced from 75.9 to 0.8 km. Fayalite-magnetite-quartz (△FMQ) and Ni-NiO (△NNO) are used as reference oxygen fugacity buffers in this study. The average oxygen fugacity of mafic magma gradually increases from △NNO-1.50 (lithospheric mantle source) to △NNO + 2.74 (near the surface) during magma evolution. Calculation results from clinopyroxene, amphibole and biotite show that the oxygen fugacity of magma increases during fractionation of clinopyroxene, plagioclase, amphibole, and biotite. However, the above fractionation cannot generate such a wide variation in oxygen fugacity. Moreover, it is not caused by degassing in terms of the low carbonate mineral content and increasing S6+/Stot ratios during fractionation. Previous studies have shown a rapid cooling and a high H2O content of the Jiaodong mafic magma. Combine with the garnet-spinel transition zone of mantle lithosphere and magnetite observed in petrography, we tend to propose that the variation in oxygen fugacity of mafic magma were caused by magnetite-spinel fractional crystallization at depth. Low-pressure metamorphic amphibole and the country rocks of Late Mesozoic monzodiorite, which has a much higher oxygen fugacity than the stable range of magnetite-spinel, indicated that the secondary alteration in last stage of magma evolution may cause additional variation in oxygen fugacity. In that case, mafic lava cannot be used to determine the oxygen fugacity of source rock. [ABSTRACT FROM AUTHOR]

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The Kunyushan granitic complex in the Jiaodong Peninsula, East China, is located in the northeast part of the Sulu UHP metamorphic belt. It is the transition belt of the North China Craton and Sulu UHP metamorphic belt. Field relationship and dating results revealed five intrusive phases of the Kunyushan granitic complex were modified into gneissic fine‐grained garnet‐bearing monzogranite (G1), gneissic medium‐ to fine‐grained monzogranite (G2), medium‐ to coarse‐grained monzogranite (G3), medium‐grained monzogranite (G4), and porphyritic coarse‐ to medium‐grained monzogranite (G5). All these phases have similar rock assemblages of peraluminous, calc‐alkaline, I‐type monzogranites. The monzogranites had primitive mantle‐normalized patterns enriched in light rare earth elements (LREE) and lithophile elements (Sr, Ba, and Rb), but depleted in heavy rare earth elements (HREE) and high‐field‐strength elements (Nb, P, and Ti). LA‐ICP‐MS zircon U–Pb dating shows that the crystallization age of the Kunyushan granitic complex extends at least from 157.7–142.0 Ma. The weighted average ages of G1‐G5 were 145.6 ± 1.9 Ma, 145.8 ± 0.5 Ma, 147.2 ± 0.7 Ma, 154.2 ± 0.6 Ma, and 155.0 ± 0.7 Ma, respectively. G5 to G1, from the middle to the edge shows a trend of gradually becoming younger. Zircon grains from different phases have similar 176Hf/177Hf values from 0.281917 to 0.282298, and εHf(t) values from −27.6 to −14.0, with a weighted average of −22.6 ± 0.5, typical of crustal‐derived origin. The corresponding two‐stage model ages TCDM are from 2,910 to 2,066 Ma, with a weighted average of 2,603 ± 31 Ma. Hf–Sr–Nd–Pb isotopes and inherited zircons suggest that the parental magma of the Kunyushan granitic complex was derived from melting of basement rocks of the North China Craton and the Yangtze Craton. The magmatism presumably took place under the background of subduction and back‐arc extension of the Palaeo‐Pacific plate. We infer that the Kunyushan granitic complex was produced by partial melting of the thickened lower crust, through delamination of the thickened lower crust during the Late Jurassic. This magmatic event may mark the beginning of the extensive Mesozoic thinning of the lithosphere in East China. [ABSTRACT FROM AUTHOR]

[Display omitted] • OPLS-DA effectively distinguishes between gold-bearing and barren rocks using spectral bands of sericite. • LSTM models accurately predict high-grade gold samples using sericite spectral data. • Machine learning and SWIR spectral data as a novel approach to uncover lode gold mineralization. The Jiaodong Peninsula in the eastern North China Craton is renowned globally as a major gold province. Notably, the Jiaojia orefield is an important gold-producing district in this region, and its depths are inferred to offer substantial prospecting potential, underscoring the need for innovative exploration tools to uncover concealed orebodies. The Qianchen gold deposit in the southern part of the Jiaojia orefield is characterized by the disseminated-stockwork-style orebodies at depths of ca. –1000 to –1800 m, with three mineralization stages, namely (I) pre-ore K-feldspar-quartz stage, (II) quartz-sericite-gold-polymetallic sulfide stage (main Au mineralization stage), and (III) post-ore quartz-calcite stage. Systematic short-wavelength infrared (SWIR) spectral analysis reveals that sericite group minerals developing in Stage II are the predominant and wide-distributed alteration minerals at Qianchen. Their spectral characteristics demonstrate a shift in the Al-OH absorption feature wavelength positions (Pos2200) to longer wavelengths (>2205 nm) within the orebodies. This shift is likely due to strong water–rock interactions leading to Fe and Mg substituting for Al in octahedral sites. Orthogonal partial least squares discriminant analysis (OPLS-DA) indicates that the H 2 O, OH, and FeOH spectral bands (Variable Importance in the Projection (VIP) ≥ 1) of sericite are crucial for distinguishing between gold ores and barren wall rocks. Additionally, Long Short-Term Memory (LSTM) models demonstrate that spectral data of sericite can be used to predict ore samples with an accuracy of 82 %, validated by receiver operating characteristic analysis (84 %), and blind test results demonstrate that the predicted grade closely aligns with the actual grade. Therefore, it is concluded that SWIR spectral characteristics of sericite group minerals can serve as an effective indicator for prospecting the Qianchen concealed gold mineralization. This study highlights the potential of coupling between machine learning and SWIR spectral data of alteration minerals to uncover the concealed lode gold mineralization. [ABSTRACT FROM AUTHOR]

The Xiling gold deposit (>592 t @ 4.02 g/t) in the eastern Zhaoyuan-Laizhou gold belt of the Jiaodong Peninsula, is currently the largest gold deposit and deepest gold mine in China. This study presents microthermometric fluid inclusions data on quartz gangue, as well as trace element and S isotope data on pyrite from different mineralization stages and depths in the Xiling gold deposit to provide new insights into the spatio-temporal evolution of the ore-forming fluid that led to a giant Early Cretaceous gold deposit in the Jiaodong Peninsula. The δ34S values of pyrite range from 7.5 to 15.2 ‰, but vary temporally and spatially, reflecting a changes in physicochemical conditions as the ore-forming fluid migrated to different crustal levels over time, also suggesting Precambrian basement as the principal sulfur source. Trace element analyses of pyrite revealed that ore-forming metals were scavenged from the wall rock and then incorporated into the pyrite. Fluid inclusions data reveal that the ore-forming H 2 O-CO 2 -NaCl ± CH 4 fluid had a medium to high temperature (283–401 °C), medium-low salinity (1.91–8.00 wt% NaCl equivalent), analogous to most gold deposits in the Jiaodong Peninsula. Intensive interaction between the ore-forming fluid and wall rock changed the physicochemical conditions of fluid, leading to gold precipitation. The study supports the notion of the ore fluid of Jiaodong-type gold deposit having originated from a metasomatized lithospheric mantle. • Spatio-temporal fluid evolution is recorded by sulfur isotopes and trace element contents of pyrite. • The ore-forming fluids formed in a H 2 O-CO 2 -NaCl ± CH 4 hydrothermal system • The intensive fluid-rock interaction is the key for Xiling gold mineralization. • The Xiling deposit can be classified as the Jiaodong-type gold deposits. [ABSTRACT FROM AUTHOR]

[Display omitted] • A wide variety of Te/Bi-minerals originated from a new fluid pulse. • The LMCE melt in hydrothermal fluids can efficiently extract gold. • The reduction of marine sulfates was crucial for the large-scale gold mineralization in the Jiaodong. The mechanism of gold migration, enrichment, and precipitation in forming world-class gold deposits has been a topic of wide interest, particularly where these deposits are abundant in tellurides. The Jiaodong Peninsula in eastern China hosts some of the world-class gold deposits among which the Jinqingding deposit is one of the best examples with substantial telluride mineralization and thus provides opportunity to investigate the genetic connection between tellurium and gold mineralization. The orebody in this deposit is hosted in the NE-NNE-trending Jiangjunshi-Quhezhuang fault with the Jurassic Kunyushan granitic pluton as wall rock. The deposit involved three mineralization stages as inferred from assemblages and crosscutting relationships between veins. These stages are: (I) pre-ore gold-poor quartz-pyrite veins, (II) main ore auriferous quartz-pyrite-Te/Bi-minerals ± sphalerite ± chalcopyrite ± barite ± marcasite veins, and (III) post-ore quartz-calcite veins. We present here the textural, isotopic, and geochemical variations of different stages/generations of pyrite based on scanning electron microscopy-energy dispersive spectroscopy (SEM–EDS), electron probe microanalysis (EPMA), and laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS). Pyrite in the Jinqingding deposit displays distinct characteristics. Py1a shows a porous and dissolution-reprecipitation texture in the core, whereas Py1b exhibits a smooth and flat rim. Geochemical analysis reveals contrasting elemental compositions, with Py1a characterized by low Au (avg. 0.14 ppm), As (avg. 15.57 ppm), Ag (avg. 17.71 ppm), and Te (avg. 19.22 ppm) contents, but elevated Co (avg. 1068.10 ppm) and Ni (224.12 ppm) concentrations, and variable sulfur isotopic composition (δ 34S V-CDT = 9.54‰–12.12‰). Conversely, Py1b displays increased concentrations of these elements and a more concentrated δ 34S V-CDT value (11.99‰–12.23‰), possibly associated with weak coupled dissolution-reprecipitation (CDR) processes. In Stage II, pyrite can be further categorized into two generations: the porous core (Py2a) and the smooth periphery (Py2b). Notably, Stage II exhibits increased contents of Au (Py2a: avg. 0.47 ppm; Py2b: avg. 5.57 ppm), As (Py2a: avg. 1265.20 ppm; Py2b: 1049.46 ppm), Ag (Py2a: avg. 5.43 ppm; Py2b: avg. 65.23), and Te (Py2a: avg. 21.47 ppm; Py2b: avg. 51.66 ppm), δ 34S V-CDT value exhibits minor changes (Py2a: 11.48‰–13.05‰; Py2b: 11.79‰–12.80‰). These changes potentially indicate the involvement of a fluid pulse characterized by low f O 2 : −34.9 to −30.2, medium f Te 2 : −14.7 to −10.9 and f S 2 : −11.4 to −6.9. Despite the dissolution-reprecipitation textures present in the ores, gold did not undergo remobilization, except for a possible weak contribution in Stage II. The presence of abundant Bi/Te-minerals underscores the significant role of low-melting point chalcophile elements in gold migration and enrichment. By compiling and analyzing sulfur isotopic composition of gold deposits across the entire Jiaodong Peninsula, which shows the reduction of marine sulfates as a crucial mechanism for sulfur enrichment. We conclude that the Jinqingding gold deposit, characterized by abundant tellurium, along with episodic pulses of ore-forming fluids, and exhibit subtle distinctions compared to other gold deposits within the Jiaodong Peninsula. [ABSTRACT FROM AUTHOR]

Migmatite, generated from anatexis or partial melting, links metamorphism with magmatism and can be used to investigate the source of magmas. Zircon and titanite, as refractory minerals in migmatite, can illuminate both the conditions of partial melting and the sources of associated granites. Mesozoic granitoids in the Jiaodong Peninsula, eastern China, have been studied extensively for their origins as partial melts of the lower continental crust. However, Jurassic metamorphism and partial melting of their hypothesized parent rocks have rarely been reported and discussed. In this study, we investigated the morphology, interior structure, U-Pb geochronology, and trace element compositions of zircon and titanite from diverse migmatites in the Yantai-Rushan area of the Jiaodong Peninsula. For leucosomes, inherited metamorphic and magmatic (or anatectic) zircon cores yield Paleoproterozoic ages, indicating a North China affinity; in contrast, anatectic zircon domains with high rare earth element concentrations show Jurassic ages of 160–154 Ma. For mafic melanosomes, metamorphic zircon and titanite yield ages of 154–149 Ma and c. 150 Ma, respectively; in contrast, two inherited metamorphic zircons record Triassic ages, suggesting an affinity with the ultrahigh-pressure rocks in the Sulu orogen. For granites, the oldest age of anatectic zircons is 175 Ma. Altogether, these data demonstrate a long-lived (c. 25 Myr), Jurassic, metamorphic-anatectic event in the Jiaodong Peninsula. These new findings prove that three lithotectonic units—the Jiaobei terrane, Sulu orogen, and preexisting granites in the Jiaodong Peninsula—were all sources for protracted Jurassic partial melting. This study deepens our understanding of the links between metamorphism and magmatism in demonstrating the diverse rock types that simultaneously source granites. • A Jurassic metamorphic-anatectic event was identified in the Jiaodong Peninsula of eastern China. • Rocks of North and South China block affinity were co-involved in the Jurassic partial melting. • This provides robust evidence for multiple origins of Jurassic and later granitoids. [ABSTRACT FROM AUTHOR]

The intrusive age ranges of Linglong, Guojialing, Weideshan, and Laoshan granites in the Jiaodong Peninsula are 155–154 Ma, 131–130 Ma, 118–111 Ma, and 116 Ma, respectively. Together with the Shidao granite (227–200 Ma), five phases of magmatism can be classified by the time, all of which have different degrees of gold and polymetallic mineralization. The type of granites evolved from A–, S–type to I–, A–type from the Late Triassic to the Early Cretaceous, thus reflects the evolution of geodynamics in the Mesozoic, indicating the switch from North China Craton (NCC)–Yangtze Craton (YC) collision to subduction of the Paleo–Pacific Plate (PPP), with crustal thickening switching to lithospheric thinning and a compressional tectonic setting changing to an extensional setting. It directly leads to a series of extensional structures evolving in the Jiaodong Peninsula and demonstrates affinity for the extensive mineralization in the Early Cretaceous. The key markers of Jiaodong gold and polymetallic mineralization are magmatism, fluid activity and extensional structure. Extensive magmatic uplift and extensional structures in the Early Cretaceous formed the extensional tectonic system. During the formation process, a large proportion of crust and mantle materials exchanged and mixed, and the fluid interaction was highly active, resulting in a magmatic fluid metallogenic system, which provided favorable metallogenic conditions for gold and nonferrous metal hydrothermal deposits. Thus, a large-scale explosive mineralization occurred in Jiaodong in the middle and late Early Cretaceous.

The Xiawolong gold deposit, located in the Muping–Rushan gold metallogenic belt (eastern Jiaodong Peninsula), is a newly discovered deposit that developed in the late Early Cretaceous as fine-grained granite. Gold mineralization, which mainly occurs in the middle of fresh fine-grained granite dikes, consists of stockwork-style and disseminated ores. They are characterized by middle-high-temperature mineral assemblages, such as molybdenite and magnetite, associated with gold-bearing pyrite. Four types of primary fluid inclusions, contained within the quartz grains from the gold-bearing disseminated and stockwork-style fine-grained granitic ores, were identified based on microthermometry and Raman spectroscopy. The types identified were type 1 aqueous inclusions with middle-high temperature (201 to 480 °C) and middle-low salinity of 0.18 to 17.00 wt.% NaCl equiv.; type 2 H2O–CO2 inclusions, which show middle-high temperatures (218 to 385 °C), middle-low salinities (1.23 to 13.26 wt.% equiv. NaCl), and variable XCO2 (0.031 to 0.044); type 3 daughter mineral-bearing inclusions with high temperature (416 to 446 °C) and relatively constant and high salinity (28.59 to 32.87 wt.% NaCl equiv.); and type 4 CO2 fluid inclusions, which possess a bulk density of 0.405 to 0.758 g/cm3 and a constant XCO2 (0.952 to 0.990) (according to the decreasing abundance of fluid inclusions). The δ18Owater range is between 3.4 and 5.9‰, and the range of the δD is from −97.1 to −77.4‰, which indicates that the ore-forming process is of a magmatic water origin. The δ34S values possess a narrow range between 4.5 and 9.3‰, indicating the source of the Mesozoic Kunyushan granitoids. The Pb isotopic compositions of pyrite show that the Mesozoic Kunyushan granitoids are the main lead source for pyrites. Types 1, 2, and 3 fluid inclusions coexist in the same view field of the quartz grain, which are suggested to occur as the result of fluid immiscibility because of the boiling of a single homogeneous NaCl-CaCl2-KCl-CO2-H2O system. The fluid immiscibility, rather the fluid mixing and wall-rock sulfidation, is the mechanism of gold precipitation in the Xiawolong deposit. Compared with both the “Linglong-type” and “Jiaojia-type” gold deposits in the Jiaodong Peninsula in terms of geological–petrographic evidence and all of the available geochemical data, it can be concluded the Xiawolong gold deposit is of magmatic hydrothermal origin, having a genetic relation to the fine-grained granite.

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.

With the rapid development of urbanization, the disorderly expansion of land use for urban construction has led to increasingly severe spatial dislocations of ecological land and construction land, and the topic of rationally planning the scale of urban land use and controlling urban sprawl from the perspective of ecological security has become a challenge for many countries. This paper considers the Jiaodong Peninsula as the study area. The ecological sources were obtained by integrating the results of an ecological importance assessment and the data on nature reserves, a basic ecological resistance surface was built, and ecological corridors and buffers were identified using a minimum cumulative resistance model. Three development scenarios were designed for 2015–2030 based on future land use simulation (FLUS) model, namely, natural development (ND), core ecological patch protection (CEP) and ecological security pattern restriction (ESPR). The ND scenario followed the land expansion rate from 2005 to 2015; the CEP scenario used the ecological sources as a forbidden conversion area, and the ESPR scenario used the ecological security pattern as a forbidden conversion area. A multiscale evaluation system based on the ecological security index (ESI) and the landscape pattern was established to analyze the three scenarios in detail. The main conclusions were as follows: (1) the area of ecological sources of the Jiaodong Peninsula was 3296.85 km2, and 13 ecological corridors were identified, and (2) in the multi-scale ecological security evaluation, the ND scenario destroys the original ecosystem structure of the region, which is not conducive to regional ecological conservation; the CEP scenario still has a trend of landscape fragmentation, and the ESPR scenario performs well in all aspects. Based on the landscape pattern, it was observed that the ESPR scenario had the largest landscape diversity and the most uniform distribution pattern, and the landscape dominance and heterogeneity were both the best. This finding indicated that imposing the ecological security pattern could make it possible to effectively control the spatial form of construction land, avoid excessive dispersion of landscape types, and form a stable and secure ecological pattern. This study can provide an important reference for spatial boundary control of urban development and construction and the formulation of related ecological protection policies.

The Jiaodong Peninsula is one of the most important Au ore provinces in China. There is an ongoing debate on the correlation between ore formation and magmatism in this province, because few intrusive rocks exhibit a clear association with ore deposits. A mineralized biotite monzodiorite (BM) stock, with disseminated ore, pervasive phyllic alteration, and no deformation, was found in a borehole in the footwall of the Zhaoping fault within the Luanjiahe Au deposit, which may shed light on this debate. The biotite monzodiorite contains explosion breccias, miarolitic cavities, skeletal and dendritic quartz, and late-stage evolved aplite dikes, and the in-situ δ34S values of the disseminated pyrite which is associated with Au mineralization are −1.7‰ to 7.3‰ (mean=3.5‰), indicative of a magmatic-hydrothermal system. These findings, combined with the reported age of 123 Ma, show that the intrusion has close spatial, temporal, and geochemical relationships with Au mineralization in the area. The biotite monzodiorite is metaluminous, high-K calc-alkaline and shoshonitic, with enrichment in light rare earth elements (REEs) and large-ion lithophile elements (LILEs), depletion in high-field-strength elements (HFSEs), and enriched Sr-Nd isotopic compositions. The intrusion may be the product of partial melting of enriched lithospheric mantle with a small lower crustal component. The hydrous, Au-bearing, enriched mantle source, and the strongly oxidized magma that was generated, created favorable conditions for Au mineralization. [ABSTRACT FROM AUTHOR]

Large-scale gold mineralization during the Early Cretaceous is identified in the Jiaodong Peninsula of China. Sources of ore-forming fluids remain debated. We study the Qilishan gold deposit in the northwestern Jiaodong Peninsula with detailed mineralogical observation and in-situ sulfur isotope analyses, in order to reveal the gold occurrence and the origin of ore-forming fluids. The Qilishan gold deposit is mainly clastic altered rock-type in mineralization, and ore minerals are visible native gold, electrum, pyrite, chalcopyrite and galena, gangue minerals as quartz, sericite and calcite. The gold occurrence includes inclusion and intergranular types, formed within pyrites and chalcopyrites and along their fissures. In-situ sulfur isotope analysis of gold-bearing sulfides suggests that the Qilishan deposit is enriched in heavy sulfur, with δ34S values mainly from +8.0‰ to +12.0‰. δ34S values increase gradually with the fluid evolution from the early to late stages, which is interpreted to be related to the loss of sulfur via sulfide precipitation. The crystallization of sulfides from hydrothermal fluids may have triggered the instability of Au(HS)2, and finally led to gold precipitation. Combined with sulfur isotope compositions of other gold deposits (n=43) and wall-rocks in the Jiaodong Peninsula, it is proposed that the ore-forming fluids were probably not directly originated from metamorphic wall-rocks (e.g., Jiaodong Group). Moreover, the relatively long time interval rules out the possibility that the gold mineralization (ca. 120 Ma) was associated with granitic magma activities (mostly 160–150 Ma). Possible ore genesis scenario is that, long-term subduction of slabs (e.g., the Paleo-Pacific) with gold-enriched pyritic materials and crustal sedimentary rocks resulted in both high Au contents and positive δ34S values of sulfur in the lithospheric mantle below the North China Craton. Subsequently, devolatilization of the metasomatized mantle produced auriferous fluids that migrated upward along translithospheric fault systems, and gold finally precipitated in favorable structural positions, generating the world-class Jiaodong deposits in the Early Cretaceous. [ABSTRACT FROM AUTHOR]

The North China Craton is one of China’s major gold-producing areas. Breakthroughs have been continually made in deep prospecting at depths of 500–2000 m in the Jiaodong Peninsula, and geophysical methods have played an important role. Given that the geophysical signals of deep-seated gold deposits are difficult to detect, due to their thick overburden layers, conventional geophysical methods are not suitable for deep prospecting. Therefore, this study upgrades the geological-geophysical prospecting model, which is based on the deep metallogenic model and geophysical method of large exploration depths. Based on the analysis of the metallogenic geological factors of the altered-rock-type gold deposits in the fracture zones of the Jiaodong Peninsula, this study proposes that the gold deposits are controlled by large-scale faults, generally occur near the contact interfaces between the Early Precambrian metamorphic rock series and Mesozoic granitoids, and exhibit a stepped metallogenic model. This model then becomes the prerequisite and basic condition for deep prospecting by geophysical methods. For this reason, the traditional geophysical model, which focuses on the exploration of shallow mineralization anomalies, is transformed into a comprehensive multi-parameter geological-geophysical qualitative prospecting model highlighting the exploration of ore-controlling structural planes. The model adopts various frequency domain methods (e.g., CSAMT, AMT, WFEM), reflection seismology, and other methods to detect the deep geological structure. The characteristics of parameters such as gravity and magnetism, resistivity, polarizability, and the seismic reflection spectrum are applied to identify the ore-controlling fault location and dip angle change, and to estimate the ore-bearing location according to the stepped metallogenic model. The prospecting demonstration of deep-seated gold deposits in the Shuiwangzhuang mining area indicates the effectiveness of the comprehensive model. The comprehensive deep prospecting model effectively solves the problem of deep prospecting of gold deposits controlled by faults, promotes the great breakthrough of deep prospecting in the Jiaodong Peninsula, and provides an important technology demonstration for deep prospecting throughout China.

The Late Mesozoic tectonic evolution of the eastern North China Craton (NCC) remains controversial. In this study, a suite of Early Cretaceous mafic-intermediate dyke swarms found in the same section in the Jiaodong Peninsula, eastern NCC, were used to trace the nature of lithospheric mantle and crust–mantle interaction. Zircon U-Pb dating demonstrates that these dykes emplaced into the Jiaodong Peninsula during the same period (112–121 Ma). Diorite dykes have SiO2 contents of 52.7–54.1 wt.%, Na2O+K2O contents of 5.77–6.10 wt.%, a limited range of MgO (4.43–5.13 wt.%), Cr (64.8–85.5 ppm) and Ni (23.6–27.7 ppm), and a narrow range of (87Sr/86Sr)i isotopic ratios (0.709240–0.709246), ƐNd(t) values (−20.0 to −19.1) and ƐHf(t) values (ca. −23.9). Lamprophyre and dolerite dykes have low contents of SiO2 (50.5–55.4 wt.%) and Na2O+K2O (4.88–7.28 wt.%), high contents of Al2O3 (14.6–15.8 wt.%), MgO (5.83–8.60 wt.%), Cr (210–292 ppm) and Ni (114–149 ppm), and a narrow range (87Sr/86Sr)i isotopic ratios (0.709134–0.709788), ƐNd(t) values (−19.9 to −17.4) and ƐHf(t) values (−22.1 to −15.1). Both intermediate and mafic dykes exhibit strong large ion lithophile elements (LILE) enrichment and high field strength element (HFSE) depletion. These geochemical characteristics demonstrate that the magma was primarily derived from relatively low degrees of the partial melting of garnet-lherzolite mantle, which was modified by fluids from a subducting oceanic slab with marine sediments. Both the mafic dykes and intermediate dykes originated from the same magma source and formed in different stages of magma fractionation crystallization. The magma experienced the fractional crystallization of clinopyroxene and more ferromagnesian minerals in a hydrous condition, thus forming mafic dykes. Then, the residual calc-alkaline liquids upwelled into a low-H2O and low-pressure environment, in which more plagioclase crystallized from liquid, thus increasing the degree of differentiation and producing the Ca- and Al-rich diorite dyke. Combined with Late Mesozoic mantle-derived mafic-intermediate dykes and crust-derived volcanic rocks in the region, the eastern NCC has experienced considerable lithospheric thinning along with regional extensional tectonics, which was caused by the prolonged thermo-mechanical-chemical erosion on the lithosphere induced by the rollback of the subducted paleo-Pacific plate. [ABSTRACT FROM AUTHOR]

The Majiayao gold deposit at Qixia in Shandong Province is a typical gold deposit of medium–low temperature hydrothermal veins. This gold deposit is one of the most important types in the Jiaodong Peninsula. Four stages have been identified based on the cross‐cutting relationships and mineralogical and textural characteristics. The study of quartz vein fluid inclusions show that the inclusions can be divided into three categories: pure liquid or pure gas phase inclusions (type S), two‐phase gas and liquid inclusions (type W), and three‐phase inclusions rich in CO2 (type C). The results of laser Raman probe analysis show that the fluid inclusions are generally rich in CO2, thus forming a typical CO2–H2O–NaCl system. The fluid temperature results show that in stage I, only the type W fluid inclusions are identified by microthermometry, the homogenized temperatures (to liquid) are 210–343°C and mostly range from 260 to 280°C, the range of salinity is 1.57–10.98 wt.% NaCl, with a peak value of 8–11 wt.% NaCl, and the density is 0.65–1.02 g/cm3, with a peak value of 0.81–0.87 g/cm3; in stages II and III, the primary fluid inclusion assemblages include both type W and C inclusions, which show similar phase‐transition temperatures and are trapped between 190 and 300°C, and the peak values of salinities are 4–10 wt.% NaCl equivalent; and in stage IV, the total homogenization temperatures (Th‐TOT) into liquid range from 120 to 220°C, and the range of salinities is 4.2–7.9 wt.% NaCl. These values indicate that temperature, salinity, and density gradually decreased from the early to late mineralization stage. The ore‐forming fluid of the deposit was a thermal liquid system with medium–low temperature, medium–low salinity, and low density and was rich in reducing CO2. The H–O isotope shows that the ore‐forming fluids were dominated by metamorphic fluid with only minor amounts of meteoric water involved in the ore‐forming process. According to the S, Pb, and Sr isotopes analysis, it indicated that the source of ore‐forming materials is mainly crustal fluid. The measured Rb–Sr isochron age of pyrite is 123.4 ± 2.9 Ma, which indicates that the metallogenic age corresponded to the Early Cretaceous. [ABSTRACT FROM AUTHOR]

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There are thousands of earthquakes every year, but most of them are small and are not disasters. This study explored whether non‐destructive earthquake experience affects public risk perception and motivates preparedness. The study respondents were from the Jiaodong Peninsula, China, where more than 20 small earthquakes have occurred during the past decade. The results show that non‐destructive earthquake experience positively affected public perception of the probability of an earthquake but not the perception of consequences. The relationship between non‐destructive earthquake experience and preparedness intention was not statistically significant. In addition, this study revealed that the perception of consequences was a positive predictor of earthquake preparedness intention, that is people with higher levels of perceived consequences of an earthquake were more likely to be motivated to prepare. However, non‐destructive earthquake experience moderated this relationship, that is weakened the strength of this relationship between perceived consequences and skill preparedness intention. These findings permit the identification of potential pathways to increase levels of disaster preparedness and potential barriers to enhancing disaster resilience in regions experiencing small hazards. [ABSTRACT FROM AUTHOR]

Groundwater is the primary source of water for domestic use and agricultural irrigation in Jiaodong Peninsula. This study collected 80 groundwater samples from Jiaodong Peninsula to characterize groundwater hydrogeochemical processes and the suitability of groundwater for domestic use and agricultural irrigation. The groundwater of Jiaodong Peninsula was categorized as slightly alkaline freshwater, with a Piper diagram classifying most samples as SO4·Cl-Ca·Mg and HCO3-Ca·Mg types. Major ions were Ca2+, Na+, SO42−, and HCO3−. The major processes driving the hydrochemistry of groundwater were identified as water-rock interactions as well as evaporation. The dissolution of silicate and cation exchange were the predominant hydrogeochemical processes responsible for groundwater chemistry. Four water samples showed seawater intrusion and some indicated pollution from anthropogenic activities such as industry, agriculture, and domestic sewage discharge. Overall, it was found that groundwater in most areas of Jiaodong Peninsula is suitable for domestic use and agricultural irrigation. [ABSTRACT FROM AUTHOR]

A section from the Linglong gold deposit on the northwestern Jiaodong Peninsula, East China, containing Late Mesozoic magmatic rocks from mafic and intermediate dikes and felsic intrusions, was chosen to investigate the lithospheric evolution of the eastern North China Craton (NCC). Zircon U–Pb data showed that low-Mg adakitic monzogranites and granodiorite intrusions were emplaced during the Late Jurassic (~145 ​Ma) and late Early Cretaceous (112–107 ​Ma), respectively; high-Mg adakitic diorite and mafic dikes were also emplaced during the Early Cretaceous at ~139 ​Ma and ~118 ​Ma, and 125–145 ​Ma and 115–120 ​Ma, respectively. The geochemical data, including whole-rock major and trace element compositions and Sr–Nd–Pb isotopes, imply that the mafic dikes originated from the partial melting of a lithospheric mantle metasomatised through hydrous fluids from a subducted oceanic slab. Low-Mg adakitic monzogranites and granodiorite intrusions originated from the partial melting of the thickened lower crust of the NCC, while high-Mg adakitic diorite dikes originated from the mixing of mafic and felsic melts. Late Mesozoic magmatism showed that lithosphere-derived melts showed a similar source depth and that crust-derived felsic melts originated from the continuously thickened lower crust of the Jiaodong Peninsula from the Late Jurassic to Early Cretaceous. We infer that the lower crust of the eastern NCC was thickened through compression and subduction of the Palaeo-Pacific plate beneath the NCC during the Middle Jurassic. Slab rollback of the plate from ~160 ​Ma resulted in lithospheric thinning and accompanied Late Mesozoic magmatism. Image 1 • Late Mesozoic low-Mg and high-Mg adakitic rocks are found in the northwestern Jiaodong Peninsula. • NCC lower crust thickened via compression and Middle-Jurassic subduction of Palaeo–Pacific plate. • The low crust of NCC is invariable and its lithospheric thinning occurred at the lithospheric mantle depth. • Slab rollback at ~160 ​Ma caused lithospheric thinning and Late Mesozoic magmatism. [ABSTRACT FROM AUTHOR]

The significant Late Mesozoic thinning of lithospheric mantle in eastern China caused the formation of many basins and intensive volcanism. Crust exhumation process is a crucial part of supracrust response of lithosphere destruction. It has been studied in order to constrain the model of Late Mesozoic thinning of lithospheric mantle. The Sulu orogenic belt and the Jiaobei Terrane underwent a substantial exhumation process in Early Cretaceous, and though many studies have been carried out to investigate its exhumation history, it is still lacking understanding. Extensional terrestrial domain of the Jiaolai Basin was formed along with the Early Cretaceous exhumation of the Jiaobei Terrane and the Sulu orogenic belt. It provides an ideal research object for studying the exhumation process of Jiaodong Peninsula in Early Cretaceous because of the continuous sedimentary record in the basin. In this study, we analysed detrital zircon geochronology of three sandstone samples from Early Cretaceous sediments in north‐eastern part of the Jiaolai Basin. Detrital zircon age spectrums indicate that zircon ages consist mainly of six clusters, and they comprise Neoarchean ages, Palaeoproterozoic ages, Neoproterozoic ages, Triassic ages, Jurassic ages, and Early Cretaceous ages. The study shows that the Jiaobei Terrane and the Sulu orogenic belt served as source areas that provided detrital materials for Early Cretaceous strata in the Jiaolai Basin. Our results, along with those of previous studies, suggest that Jiaobei Terrane and the Sulu orogenic belt in Jiaodong Peninsula had discrepant exhumation history in Early Cretaceous. [ABSTRACT FROM AUTHOR]