The Wuyi metallogenic belt is a key part of the world-class South China tungsten province, but its metallogenic regularities are poorly constrained. Here, we present chronological and geochemical data from U-Pb geochronology, O isotopes, and trace elements in zircon, monazite, and wolframite for the Xingluokeng large-scale, Guomuyang medium-scale, and Beikeng small-scale W deposits in this belt. This study reports the first granite emplacement ages and W mineralization ages for the Guomuyang and Beikeng deposits. The results show that the Guomuyang biotite granite (similar to 435 Ma) and the Beikeng early-stage biotite granite (410-413 Ma) were emplaced during the Early Paleozoic, but these host granites have no direct genetic relationship with the Late Jurassic W mineralization (Guomuyang, similar to 144 Ma; Beikeng, similar to 150 Ma). This interpretation is further supported by the weakly fractionated nature of the Early Paleozoic granites, such as high K/Rb and low Rb/Sr ratios. The fertile granites are interpreted respectively as a concealed intrusion at Guomuyang and a younger muscovite granite cupola at Beikeng. Wolframite from these three deposits exhibits consistent REE patterns and delta O-18 values (Guomuyang, 2.92-4.76 parts per thousand; Beikeng, 2.44-3.71 parts per thousand; Xingluokeng, 3.50-4.70 parts per thousand), indicating a magmatic-hydrothermal origin typical of quartz-vein-type W deposits. However, significant differences exist in trace element compositions: wolframite from Xingluokeng exhibits higher Nb, Ta, and Sc and lower Nb/Ta ratios than Guomuyang and Beikeng. This fluid signature is consistent with a highly differentiated, reduced, and acidic magmatic-hydrothermal system, which would have favored efficient tungsten transport, thereby likely contributing to the substantially higher WO3 endowment at Xingluokeng. Overall, these chronological and geochemical data, together with those from other W deposits in the same belt, indicate that granitic magmatism and W mineralization in the Wuyi metallogenic belt peaked in the Late Jurassic, showing a strong temporal correlation with the adjacent Nanling metallogenic belt.

Wolframite ([Fe,Mn]WO4) and scheelite (CaWO4) are the predominant ore minerals of tungsten. Whether their existence in tungsten deposits is singly caused by the Ca content of host rocks is poorly constrained. The solubility differences and precipitation mechanisms of wolframite and scheelite from hydrothermal fluids were examined using thermodynamic modeling programmed in the open-source R language. The updated model parameters can well reproduce the available experimental data for these two tungstates. The modeling results suggest that scheelite is more soluble than hubnerite (MnWO4) in NaCl-H2O fluids, and hubnerite more soluble than ferberite (FeWO4). Two mechanisms can cause scheelite to replace ferberite (hubnerite): cooling plus a rise in the Ca/Fe (Ca/Mn) molality ratio in fluids and a decrease in fluid pressure. The second mechanism is identified for the first time. These two mechanisms are independent of the existence of CO2 in the fluids. The combined influence of temperature, pressure, and cation supply (e.g., Ca2+) from host rocks would produce a zonation where wolframite is more likely precipitated in the inner parts, while scheelite easily occurs in the outer parts of the same ore system.

The granites associated with large-scale W and Sn deposits generally have high concentrations of U, Th, and K, including but not limited to the Cornubian Batholith in Southwest England, the Krušné hory/Erzgebirge Batholith in Central Europe, the Sardinian Batholith in Italy, and the Gejiu Batholith and the Qianlishan granitic complex in South China. These granites can be classified as high heat producing (HHP) granites (>5 μW m-3) because of high radiogenic heat production. However, how long radiogenic heat can prolong the suprasolidus lifetime of magmas and whether radiogenic heat exerts an influence on later W and Sn mineralization is poorly understood. To answer these questions, finite element numerical modeling was established to link magma cooling by heat conduction with diffusion of W, Sn, and H2O from silicate melts to coexisting aqueous fluids before the solidus is reached. The magma size (vertical thickness of 4–5 km and horizontal length of 20 km) is constrained by the granites associated with large-scale W and Sn deposits. The modeling results suggest that the suprasolidus lifetimes of HHP magmas are positively correlated with the heat production and magma thickness and negatively correlated with the solidus temperatures and the thermal conductivity of host rocks. Average radiogenic heat of 5–10 μW m-3, together with decreased solidus temperatures due to magmatic differentiation and a moderate thermal conductivity of host rocks, can prolong the suprasolidus lifetime of HHP magmas by 49–427 ka (1 Ma = 1000 ka), corresponding to 11–85 % of the suprasolidus lifetime of equally sized magmas with normal radiogenic heat (2 μW m-3). From the available gravity modeling data, over half of the granites associated with large-scale W and Sn deposits are at least 1 km thicker than the values calculated from the empirical power–law equation, and the modeling results indicate that an increase of 500–1000 m in magma thickness prolongs the suprasolidus lifetimes of HHP magmas (5 μW m-3) by 50–74 %. During magma cooling before solidus is reached, the diffusion of W and Sn is at least several orders of magnitude slower than that of H2O in hydrous melts; thus, the equilibrium partitioning of these two metals between silicate melts and coexisting aqueous fluids is not reached, and the metal diffusion from melts is a rate-limiting step. The prolongation of the suprasolidus lifetimes by radiogenic heat and decreased solidus temperatures can allow extraction of 17–95 % more W and Sn from silicate melts before the solidus is reached and increase the possibility of producing W and Sn mineralization at later stages. Therefore, the coexistence of HHP granites and large-scale W and Sn deposits is not accidental.

Peraluminous granites are commonly considered to be the product of crustal reworking in continental interiors and have a genetic relationship to Sn-W-rare metals deposits (e.g., Li, Be, Nb, Ta, Cs, Rb), but the heat transfer mechanisms responsible for the formation of peraluminous magmas and the mantle roles in these physical processes remains controversial. To answer these questions, the origin of the Xingluokeng granite in the Wuyi terrain of South China, peraluminous granite hosting large-scale tungsten mineralization, was investigated using zircon UPb and Hf isotopic compositions and numerical modeling of heat transfer with geologically relevant ranges of the ancient crustal thickness and heat production. The strongly negative epsilon(Hf(150M)) values (-25.72 -7.01) of autocrysic zircons (ca. 150 Ma), varying within those of inherited zircons (600-1000 Ma), suggest no signature of mantle mass input. The Mesozoic upper crust heat production in the Wuyi terrain estimated from fine-grained clastic sediments has an average of 2.9 mu W m(-3), and amphibolite facies to granulite facies rocks, representing the middle-lower crust, have averages of 0.6-4 mu W m(-3). These values are greater than the global present-day averages for continental crust (upper crust: 1.68 mu W m(-3); middle-lower crust: 0.19-1 mu W m(-3)). The high heat production and moderate crustal thickening (similar to 50 km), together with a normal mantle heat flux, can cause partial melting of metasedimentary rocks in the middle-lower crust within a thermal relaxation period of similar to 30-50 Ma. Crustal radiogenic heating also warms the lower crust and the upper mantle and facilitates partial melting of mafic rocks, leaving volumetrically minor mafic dykes coeval with peralumnious granites in the same regions. Therefore, minor mafic dykes are not convincing evidence for the mantle supplying heat or mass for the coeval peraluminous granites. High crustal heat production and crustal thickening is also shared by other regions in the Cathaysia Block, so the above implications may also be applicable to other Mesozoic peraluminous granites in South China.

Growing evidence suggests that extensional/transtensional settings are favorable for the formation of tin deposits, yet the underlying geodynamic mechanism remains equivocal. The Pingna W-Sn deposit, found in the underexplored interior of the giant tin belt within the Youjiang Basin, South China, offers a unique opportunity to explore and better constrain the current geodynamic model for tin mineralization. This deposit, composed of NW- to NWN-striking vein swarms with W-Sn mineralization, is hosted in the Middle Triassic clastic rocks without igneous rocks near its mineralization. Structural analysis indicates that the Youjiang fold-and-fault belt and the ore-related structures in the Pingna deposit experienced five deformation phases (D1-D5). The pre-ore NE-striking compression (D1; rv = r3) initiated fault-fracture meshes, followed by NE-striking extension (D2), while NW-striking compression (D3; rv = r2) enhanced the vertical connectivity of the meshes. Syn-mineralization E-W extension (D4; rv = r1) facilitated upward through-going flow and hydrothermal fluids infilled the meshes, forming a fault-vein system. The mineralized veins were cut across by post-ore WNW-striking oblique fault with sinistral and normal components (D5). The meshes dictated Sn-W orebodies localization. Hydrothermal veins formed in three stages: (I) muscovitization-bordered tin-dominated quartz vein swarms along the Pingna fault; (II) W-dominated lit-par-lit vein system; and (III) barren calcite veins crosscutting the former veins. The Pingna W-Sn mineralization formed during the Late Cretaceous as constrained by the cassiterite (Cst1) U-Pb age of 95.6 +/- 2.4 Ma (2r, MSWD = 1.2), muscovite (Ms1) 40 Ar-39 Ar plateau age of 93.9 +/- 0.1 Ma (2r, MSWD = 1.7), and molybdenite Re-Os age of 92.9 +/- 1.2 Ma (2r, MSWD = 0.3). Outward lateral zoning of the Sn-W mineralization, as well as associated muscovitization and silicification implies the epicenter of hydrothermal fluid is near the No. II vein swarm. Contemporaneous felsic dykes coupling with the inferred intrusions demonstrate that the Pingna deposit is a distal hydrothermal W-Sn deposit. The releasing bend of the NW-striking Pingna fault controlled the distribution of tin-dominated mineraliza-tion, while the anticlines controlled the tungsten-dominated mineralization. Our findings suggest that the localization and formation of the Pingna W-Sn veins were controlled by Late-Cretaceous regional transtensional stress field and polyphase deformation, rather than previously proposed local extension of the Youjiang Basin. The discovery of the Pingna W-Sn deposit highlights the interior of the Youjiang Basin as a promising area for tungsten-tin exploration.(c) 2025 China University of Geosciences (Beijing) and Peking University. Published by Elsevier B.V. on behalf of China University of Geosciences (Beijing). This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). double up arrow Corresponding author at: Laboratory of Dynamic Diagenesis and Metallogen-esis, Institute of Geomechanics, Chinese Academy of Geological Sciences, No. 11, Minzudaxue South Road, Beijing 100081, China. E-mail address: xiaochanghao1986@126.com (C. Xiao). https://doi.org/10.1016/j.gsf.2025.102006 1674-9871/(c) 2025 China University of Geosciences (Beijing) and Peking University. Published by Elsevier B.V. on behalf of China University of Geosciences (Beijing). This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Scheelite and wolframite are two main tungsten-bearing ore minerals in tungsten deposits. Compared to wolframite formed mostly by NaCl-H2O fluids, scheelite in many but not all tungsten deposits is associated with CO2-bearing hydrothermal fluids, but its precipitation mechanisms from these fluids are poorly understood. The replacement of wolframite by scheelite is common among tungsten deposits where these two tungstates coexist, but how CO2, as the pH-buffering agent, affects their replacement remains unclear. To answer these questions, we first tested the pH-buffering effect of CO2 by comparing available experimental pH values of H2O-CO2 +/- NaCl solutions at 200-280 degrees C and the corresponding thermodynamic modeling results. The mean absolute errors between the calculated and experimental pH values are 0.14 log units in H2O-CO2 solutions and 0.13 log units in H2O-CO2-NaCl solutions, indicating that the calculated acitivities of H+ in CO2-bearing solutions are reliable. Then, the solubilities of scheelite, scheelite-ferberite, and scheelite-h & uuml;bnerite in NaCl-H2O-CO2 systems were modeled in this study. Our modeling results suggest that scheelite solubility in CO2-rich fluids is highly dependent on fluid pressure but is insensitive to fluid temperature. A decrease in fluid pressure from lithostatic to hydrostatic levels at a depth of 3-8 km causes CO2 escape and pH rise and precipitates over 70 % of tungsten contents in fluids on average. Therefore, CO2 escape is an efficient mechanism for precipitating scheelite from CO2-rich hydrothermal fluids. The independence of scheelite solubility on temperature at high pressures and the slightly retrograde solubility at low pressures allows CO2-rich hydrothermal fluids to carry a great amount of tungsten far away from its sources. This may be one of reasons why some scheelite deposits occur at greater distances (>500 m) from the granite or extend along its strike for several kilometers. Similar to the cases in NaCl-H2O systems, two mechanisms for scheelite replacing wolframite in CO2-rich fluids are identified, a single decrease in fluid pressure or simple cooling plus an increase in the ratios of total Ca contents to total Fe (or Mn) contents in fluids.

Objective Granitic magmas are genetically associated with magmatic-hydrothermal deposits and oil and gas reservoirs. The emplacement of granitic magmas into cooler rocks produced thermal anomaly and thermal stress, yet systematic studies on the spatial and temporal evolution of thermal stress still need to be completed. Previous numerical modeling often used rocks' linear thermal expansion coefficient at room temperature, but this parameter is highly temperature-dependent and reaches much higher levels at high temperatures. Therefore, the magnitude of the thermal stress caused by magma emplacement needs to be re-examined. A series of numerical experiments were carried out to investigate how the surrounding rock's lithology (granite or carbonate rocks), Young's modulus, thermal parameters, and the depth of magma emplacement affect the thermal stress generated by the magma in the overlying surrounding rocks. Methods Because the magma cools and eventually reaches thermal equilibrium with the surrounding strata, numerical simulation is one of the common methods to examine the thermal stress after magma emplacement quantitatively. This article used FLAC3D software to simulate the thermal stress caused by the emplacement of granitic magma into the upper crust. The differential equations we solved include the thermal conduction and linear thermoelasticity equations. The models' thermal field influences the stress field through temperature difference and the linear thermal expansion coefficient. However, changes in the stress field do not affect the thermal field, i.e., one-way coupling between the thermal field and the stress field. Results (1) Heat transfer is quicker on wallrocks with high thermal conductivity, causing a faster change in thermal stress. Compared to the high-thermal-conductivity case, the same thermal stress can be produced on wallrocks with a lower thermal conductivity after a more extended period of magma cooling. (2) The thermal stress produced by the surrounding rock's Young's modulus of 80 GPa is higher than the surrounding rock's Young's modulus of 60 GPa and 40 GPa. (3)The thermal stress simulated in the article is an order of magnitude larger than those generated using the linear coefficient of thermal expansion at room temperature. The thermal stress induced by granite surrounding rocks is nearly 30 MPa higher than that induced by carbonate rocks. (4) The thermal stress decreases with increasing distance from magma, approaching the initial stresses at nearly 2 km. (5) When the emplacement depth is shallow, both initial temperature and initial stress are lower than those in deeper emplacements; The magma room cools faster at shallow depths. Because the initial temperature of magma is the same, shallow emplacements will produce higher thermal stresses on overlying surrounding rocks. Conclusion The modeling results indicate that the thermal conductivity of surrounding rocks influences the change rate of thermal stress through the heat transfer rate. The thermal stress increases with the surrounding rock's Young's modulus. Since the average Young's modulus of granites is greater than that of carbonate rocks, the thermal stress on granite is greater than that on carbonate rocks. Either granites or carbonate rocks at high temperatures have a thermal expansion coefficient about one order of magnitude greater than that at room temperature, resulting in thermal stress of up to 100 MPa. The temperature of the surrounding rock gradually increases after the granite magma emplacement, corresponding to the increasing thermal stress. The thermal stress decreases with increasing distance from magma, exerting no influence on the initial stress of host rocks above 2 km of the granitic magma. When the magma emplacement is shallow, the combination of high thermal stress and low initial stress is more conducive to the formation and expansion of fractures in overlying surrounding rock. Significance The results of numerical simulations reveal that the thermal stresses generated by magma emplacement can affect the stress field 2 km above the magma. These localized and short-lived thermal stresses may fracture the overlying rocks, providing transport channels or ore-bearing spaces for later hydrothermal fluids.

[Objective]Sb deposits are characterized by simple mineral assemblage.The ore-forming ages,sources of ore-forming materials,and genesis of Sb deposits are controversial owing to the absence of suitable minerals for analysis.Sb resources in the South China Sb metallogenic region account for over 83%of the national total,with the Dian-Qian-Gui Sb belt in the southwest being an significant component of this region.[Methods]Taking the Longlin-Xilin Sb-Au mining district of western Guixi in the central part of the Dian-Qian-Gui Sb belt as an example,this paper systematically summarizes the ore-bearing strata,lithology of ore-bearing wall rocks,ore-bearing structures,and the coexistence relationship of Au and Sb deposits in 86 ore deposits(points)in the area.Combined with the geological characteristics of three typical deposits(Maxiong,Longtan,and Mahao)and the spatiotemporal distribution of Jurassic felsic intrusions,the inherent connection between Sb mineralization and clastic rocks and felsic intrusions was explored.[Results](1)Statistics and field works show that the most favorable ore-bearing stratum in the Longlin-Xilin mining district is the Lower Devonian Yujian Formation(D1y),followed by the Lower Triassic Luolou Formation(T1Ll)and the Middle Triassic Banna Formation(T2b).The lithologies most conducive to mineralization are carbonaceous shale,pyrite-rich sandstone,and siltstone.The Sb content in these strata or lithologies is tens or even hundreds of times higher than the crustal abundance,which has the potential for Sb mineralization.(2)Within the NWW-SEE trending Nongsang-Shijiazhai fault zone in the Longlin area,the middle and late Jurassic felsic intrusions,which have consistent spatiotemporal occurrences with Sb and Au deposits,can directly contribute to antimony mineralization(as sources of Sb and S)and indirectly influence it(as a heat source),both favoring the formation of antimony deposits.(3)Statistical results show that Sb,Au,and Sb-Au deposits account for 48%,46%,and 6%in the Longlin-Xilin district,respectively.This suggests that the ore-forming fluids for Sb and Au in the study area may originate from different sources.We also can not rule out the possibility that Sb and Au deposits derive from the same fluid.In the latter case,the precipitation of stibnite consumes H2S in the ore-forming fluid,destabilizing the Au complex in the solution and resulting in localized Au precipitation.This competition between Sb and Au in the fluid for H2S leads to a negative correlation in the grades of Sb and Au in coexisting deposits.(4)The study area experienced NS-striking compression in the Indosinian period,followed by the NW-SE shortening in the middle-late Jurassic.The intersection of NWW-SEE and NE-SW faults is the favorable ore-bearing space.The NWW-SEE faults displayed strike-slip movement in response to the NW-SE shortening,whereas the NE-SW faults exhibited transpression.Consequently,the NE-SW faults are less conducive to Sb mineralization compared to the NWW-SEE faults.The distribution direction of the NWW-SEE Douhuang-Xilin fault aligns with the axial direction of the main folds in the area,with most fault planes trending northward,displaying horizontal scratches,silicification,and extensional characteristics.The intersection of the Dohuang-Xilin fault and the NE-SW fracture exhibits significant Sb anomalies.[Conclusion]Based on the above studies,the promising areas we propose for Sb prospecting in Longlin-Xilin mining district are(1)Black shale and pyrite-rich siltstones of the Yujiang Formation in the core of the Xinzhou anticline as the key strata;(2)The periphery of the concealed intrusions within the NWW-SEE Nongsang-Shijaizhai fault(Longlin County)and the intersection area of the NWW-SEE Douhuang-Xilin fault and the NE-SW fault as the favorable areas.[Significance]The findings provide new insights into the genesis and metallogenic regularities of Sb-Au deposits in the study area,enriching the theoretical understanding of Au mineralization processes.

Cassiterite (SnO2) is the main ore mineral of tin in magmatic–hydrothermal tin deposits, but tin transport and precipitation mechanisms from hydrothermal fluids remain poorly understood. We critically evaluated aqueous tin speciation in hydrothermal fluids from extensive experimental data and thermodynamic modeling. Sn(II) chloride complexes in hydrothermal fluids exist mainly as SnCl+, SnCl2(aq), and SnCl3−. The revised Helgeson–Kirkham–Flowers model parameters of these three tin species and two tin ions (Sn4+ and Sn2+) were derived from the correlation algorithms among these parameters, and the standard molar properties of cassiterite were optimized to be internally consistent with the available thermodynamic dataset. These thermodynamic parameters, together with the available equilibrium constant equation of Sn(IV) chloride complexes, could reproduce the available solubility data of cassiterite in acidic solutions at 400–700 °C under oxygen fugacity (fO2) levels buffered by hematite–magnetite (HM) or nickel–nickel oxide (NNO). These comparisons allow modeling chemical systems of SnO2–NaCl–HCl–H2O (liquid phase) to examine tin transport and cassiterite precipitation mechanisms under tin-mineralizing conditions: 300–500 °C, 50–150 MPa, 2 molal NaCl, and fO2 levels from QFM (quartz–fayalite–magnetite) to HM. Sn(II) chloride complexes are commonly interpreted to dominate in aqueous tin speciation under fO2 = NNO, but our modeling results indicate that considerable contents of Sn(IV) chloride complexes also exist in those reduced fluids with high HCl contents, consistent with recent in situ high-temperature experiments and molecular dynamic simulations. The Sn(II)/Sn(IV) ratios in fluids depends on fO2, temperature, and HCl contents. A considerable amount of Sn(IV) possibly exist in an early mineralization stage even under fO2 = NNO; if so, redox reactions are unnecessary to precipitate cassiterite from these mineralizing fluids. We find that even if the fO2 levels are constant, simple cooling can alter mineralizing fluids to be more oxidized (e.g., from QFM to HM) and cause cassiterite precipitation, indicating that oxidizing agents are not necessary as previously thought. This explains why cassiterite can precipitate in host rocks (e.g., sandstone or quartzite) that do not provide oxidizing agents. A simple rise in fO2 levels and pH neutralization (e.g., greisenization) also cause cassiterite precipitation. Cassiterite solubility in oxidized acidic hydrothermal fluids (NNO < fO2≤HM) is high enough to account for the tin contents of fluid inclusions from typical tin deposits, but the mineralization potential of oxdized fluids is inferior to reduced fluids (fO2≤ NNO) under the same conditions.

The eastern Hebei Province (Jidong region) is a representative region of Mesozoic high heat production (HHP) granites with elevated abundance of radioactive heat-producing elements (HPEs: U, Th and K), which are closely associated with gold deposits. These HHP granites with high heat production (≥5 μW/m3) are alkali-rich, low-phosphorus and metaluminous to weak peraluminous granitoids and they have distinctively high Nb abundances. However, the genesis of these HHP granites and their implications for regional tectonic evolution and gold mineralization are still unclear. An integrated study of geochronology, petrology, whole-rock SrNd and zircon HfO isotopes and crystallization modeling was carried out in this paper. Our results indicate that HHP intrusive rocks were dominantly originated from alkali- and HPEs-rich fertile source, e.g., metasomatized subcontinental lithospheric mantle (SCLM) or reworked lower crust with heterogeneous geochemical compositions. Late Triassic Baizhangzi HHP granitic rocks have an adakite-like compositional feature (e.g., high Sr/Y), likely formed by deep melting (<50 km) of mafic lower crust with amphibole-dominated restite. Jurassic Yu'erya and Niuxinshan felsic plutons are characterized by high-silica (>70 wt%) and low Sr/Y ratios with fractionated geochemical compositions, which were interpreted as upper lower crust melting with plagioclase-dominated restite (or fractionation). They have relatively low initial 87Sr/86Sr (0.7022–0.7109), negative εNd (t), εHf (t) values (εNd (t) = −9.9 to −12.6, εHf (t)= − 7.3 – −13.7) and mantle-like or slightly higher δ18O values (average 5.8‰ – 6.2‰) with Meso-Paleoproterozoic Nd and Hf model ages (1.7–2.0 Ga). These geochemical and isotopic features unravel that HHP granites are likely originated from the HPEs-rich crustal source that was contaminated by alkaline fluids (with mafic magma) from HPEs-enriched lithospheric mantle metasomatized by recycled crustal materials. The obvious petrological and geochemical shift from late Triassic to early-middle Jurassic rocks suggests a transition of major tectonic regime in the Jidong region to the subduction of the Paleo-Pacific Plate. This geodynamic transformation likely resulted in the thinning and destruction of the lithospheric mantle at Jidong region in late Triassic to early Jurassic, which was vital for reactivation and release of HPEs, Au and Te from enriched SCLM to form HHP granites and associated gold deposits. High heat producing granites with an alkaline affinity may have a great potential for future gold exploration as a pathfinder.

The Qingchengzi Au-polymetallic district is one of the three major gold districts in the Liaodong gold metallogenic province, northeastern China. The mid-crustal deformation partitioning in northeastern China during Early Triassic is well documented, but the corresponding deformation partitioning at the shallow crust is poorly constrained. Kinematic and chronological analyses in this study indicate that the gold mineralization in Qingchengzi was associated with reactivation of ore-related faults in different orientations during Early-Middle Triassic. The reactivation of ore-related faults is generated by an overall top-to-the-north thrusting due to the oblique convergence between the North China Craton (NCC) and South China Block (SCB). This thrusting was partitioned into the EW-striking Baiyun thrust fault, NW-striking Jianshanzi fault, NE-striking Erdaogou fault, and intralayer fractures corresponding to the pre-existing Paleoproterozoic structures and highly contrasting lithological and rheological layers. Compression structures (Baiyun and Jianshanzi faults, and intralayer fractures) controlled the distribution of altered-rock type ores that were formed in a relatively closed hydrothermal system owing to fluid mixing and carbonaceous reduction. Comparatively, quartz-vein type gold mineralization is distributed in the NE-striking faults due to depressurization and vapor loss in a relatively open hydrothermal system. This study demonstrates that the gold mineralization in the Qingchengzi Au-polymetallic district recorded the deformation partitioning at the shallow crust along the oblique convergence orogen between the NCC and SCB in Early Triassic.

位于右江盆地的德保铜锡矿床是广西最大的铜矿床,目前仅有少量年代学和矿物学等方面的研究,对于该矿床流体特征、流体环境、矿床元素组成等所知甚少.通过矿石矿物的探针分析、流体包裹体岩相学和显微测温、平衡热力学计算约束了该矿床成矿流体的地球化学参数,分析了成矿阶段的流体环境.与典型矽卡岩型铜锡矿床不同的是,德保铜锡矿的石榴子石以镁铝榴石和钙铝榴石为主,含少量钙铁榴石;锡主要以类质同象富集在黄铜矿、黄铁矿等硫化物中,含量达96×10-6～627×10-6;石榴子石的流体包裹体均一温度182～249℃,平均值219℃;方解石包裹体均一温度109～215℃,平均值157℃;平衡热力学计算模拟表明,德保铜锡矿床硫逸度和氧逸度范围分别是:logfS2＞-20,-44＜logfO2＜-25.早期成矿流体温度的降低为黄铜矿沉淀提供了有利条件,锡元素伴随黄铜矿沉淀;成矿流体的氧逸度高于世界典型锡矿的氧逸度,这种高氧逸度的成矿流体环境不利于锡元素的运移及再富集,这可能是德保铜锡矿中锡较少以锡石存在的重要原因之一.

This study presents rock slab and thin section reflection mapping, element mapping by Micro-XRF (μ-XRF) analysis, and in situ cassiterite U-Pb laser ablation-inductively coupled plasma mass spectrometer (LA-ICP-MS) ages of the Xinlu Sn-Zn deposit, Nanling Sn-W belt, South China. The new results provided constraints on the age and processes of Sn mineralization and thus further discussed the role of the Paleo-Pacific plate in the formation of Sn-W mineralization in the Nanling Sn-W belt. Based on mineralogy and μ-XRF analysis, four mineralization episodes are distinguished in the Baimianshan segment, Xinlu deposit, including 1) prograde skarn stage characterized by the mineral assemblages of garnet, pyroxene, marble, hornfels; 2) retrograde skarn-sulfide composed of massive pyrrhotite, sphalerite with parts of epidote, cassiterite; 3) quartz sulfide vein stage consisting of arsenopyrite, pyrite, quartz, and 4) barren calcite crosscutting the former episodes. The time of retrograde skarn-sulfide mineralization is dated by LA-ICP-MS cassiterite U-Pb at 168.7 ± 1.3 Ma. These U-Pb ages, combined with previous geochronological studies, support one Sn mineralization event associated with the 159.5–168.7 Ma magmatism in the Guposhan-Huashan district. The Xinlu Sn-Zn mineralization and the Middle-Late Jurassic Sn-W mineralization in the Nanling belt, South China is genetically related to asthenospheric upwelling and crust-mantle interaction caused by the subduction of the Paleo-Pacific plate. Our results demonstrate that thin section reflection and μ-XRF element mapping are powerful tools for determining paragenesis in ore deposits and are highly effective to guide the selection of analytical positions for cassiterite U-Pb dating. This method may also be applicable to in-situ geochronology of other minerals.

The granites associated with world-class W and Sn deposits generally have high concentrations of U, Th, and K and can be classified as high heat producing (HHP) granites (>5 mu W m(-3)) because of high radiogenic heat production, but how long radiogenic heat can prolong the suprasolidus lifetime of magmas and whether radiogenic heat exerts an impact on W and Sn mineralization is poorly understood. To answer these questions, finite element numerical modeling was established to link magma cooling by heat conduction with diffusion of W, Sn, and H2O from silicate melts to coexisting aqueous fluids before the solidus is reached. The magma in the models is emplaced to a depth of 5 km and its size (vertical thickness of 4-5 km and horizontal length of 20 km) is constrained by the granites associated with world-class W and Sn deposits. Fluid convection was not considered in the models. The sensitivity analysis and comparison results suggest that the suprasolidus lifetimes of HHP magmas are positively correlated with the heat production and magma thickness and negatively correlated with the solidus temperatures and the thermal conductivity of host rocks. Average radiogenic heat of 5-10 mu W m(-3), together with decreased solidus temperatures due to magmatic differentiation and a moderate thermal conductivity of host rocks, can prolong the suprasolidus lifetime of HHP magmas by 49-427 ka (1 Ma = 1000 ka), corresponding to 11-85% of the suprasolidus lifetime of equally sized magmas with normal radiogenic heat (2 mu W m(-3)). From the available gravity modeling data, over half of the granites associated with world-class W and Sn deposits are at least 1 km thicker than the values calculated from the empirical power-law equation, and the modeling results indicate that an increase of 500-1000 m in magma thickness prolongs the suprasolidus lifetimes of HHP magmas (5 mu W m(-3)) by 50-74%. During magma cooling before solidus is reached, the diffusion of W and Sn is at least several orders of magnitude slower than that of H2O in hydrous melts; thus, the equilibrium partitioning of these two metals between silicate melts and coexisting aqueous fluids is not reached, and the metal diffusion from melts is a rate-limiting step. The prolongation of the suprasolidus lifetimes by radiogenic heat and decreased solidus tempera-tures can allow extraction of 17-95% more W and Sn from silicate melts before the solidus is reached and increase the possibility of producing W and Sn mineralization at later stages. Therefore, the coexistence of HHP granites and world-class W and Sn deposits is not accidental. (c) 2023 Elsevier Ltd. All rights reserved.

位于辽东地区的青城子与五龙矿集区尽管成矿大地构造背景相似,但其成矿时代、赋矿围岩及控矿构造却有明显的差别.根据对青城子矿集区金-多金属矿床及五龙矿集区五龙金矿床和四道沟金矿床成矿大地构造背景、赋矿围岩、岩浆活动时代及产状、控矿及容矿构造、成矿时代和剥蚀程度新数据及已有资料的综合分析,认为青城子矿集区金多金属矿床及五龙矿集区五龙金矿床和四道沟金矿床的成矿差异主要与晚三叠世以来剥蚀程度不同有关,在此基础上提出了辽东地区"三层楼"成矿找矿模式.该"三层楼"模式底部为赋存于中侏罗世深成变形花岗岩体内陡倾断裂带中的"五龙式"石英脉型金矿床(早白垩世成矿),中部为赋存于辽河群下部变质碎屑岩内层间断裂带中的"四道沟式"蚀变岩型及石英脉型金矿床(早白垩世成矿),而上部为赋存于盖县组碎屑岩及大石桥组大理岩硅钙面附近层间断裂带(部分为切层断裂带)的"白云式"石英脉型及蚀变岩型金多金属矿床(三叠纪成矿为主,但有晚侏罗世及早白垩世成矿的叠加).未来辽东深部找矿中要注意青城子金-多金属矿集区深部存在"四道沟式"及"五龙式"金矿床的可能,以及在五龙矿集区四道沟金矿深部存在"五龙式"金矿床的可能性.特别是在剥蚀程度相对较浅的青城子矿集区可能存在有较好的深部找矿潜力,在未来研究工作中需要加以重视.

Gravity changes related to large earthquake preparation are reported in broad seismogenic source regions, and crustal fluids may change the gravity potential and trigger earthquakes. However, what is the major factors affecting crustal fluids movement in the upper 10 km of the continental crust and altering the gravity potential is still poorly understood. In this study, we evaluated the gravity changes caused by invasion of crustal fluids into the depth of 6???10 km using finite element based numerical modeling. We conducted a series of numerical ex-periments to investigate the influences of permeability distribution, the fluid source, and the invasion depth on gravity changes. The sensitivity analysis and comparison results suggest that the invasion of high-pressure fluids increases fluid density and produces positive gravity changes within a decade. Fluid pressure is the key factor for the variations of fluid density, while temperature exerts a minor influence. Consistent with the dissipation of fluid pressure, the corresponding gravity changes are fast (>3 ??Gal/year) in the first 2???3 years of fluid invasion and become increasingly slow later. Therefore, the first few years are the more suitable time for monitoring the gravity changes caused by crustal fluids invasion. The fluid-related gravity changes are positively correlated to the porosity and permeability of rocks adjacent to the fluid source, the salinity and the scale of crustal fluids, and the initial temperatures, and are negatively correlated to the invasion depth. Transient invasion of crustal fluids can be detected by means of the high precision gravity observation under certain conditions subjected to the initial geological characteristics of the continental crust and the geochemical evolution of the fluid sources.

The Danchi fold-and-thrust belt, Guangxi, South China, contains the Mangchang, Dachang, and Wuxu large and giant Sn-polymetallic districts. It hosts more than 1.2 Mt of ore grading 1 % Sn, 6.23 Mt Zn at 2.4 %, and 1.13 Mt Sb at 1.3 %. Wuxu district is one of the Sb-Zn dominated hydrothermal districts without magmatic rocks exposing in the south of the Danchi belt. Recent drilling and exploring mining have identified a partially Sn mineralization associated with the Zn-Sb mineralization. These works provide an opportunity to evaluate the potential of tin mineralization in the south of Danchi belt and relationship among Sn, Zn, and Sb mineralization. Structural analysis suggests that the Wuxu district underwent at least three deformational phases since the Triassic. The first NE-SW shortening deformation controlled the structural framework of the Wuxu district and is expressed by NWverging thrusts and folds, axial-plane cleavages around the core of the Wuxu anticline, transverse joint sets on the limbs of the Wuxu anticline, and dilational zones in the bedding-fractures. Afterward, an E-W extension stress field produced NS-striking normal faults and reactivated pre-existing NNW-striking faults which were expressed by sinistral top-to-the north sense of shear. During this deformation, some low order dilational spaces of the NWstriking faults and bedding-fractures formed and a syn-kinematic deposition of minerals in these hosting structures to form the ore shoots. The NNW-striking faults, axial-plane cleavages, and large dilational jogs controlled the subvertical large veins in the Jianzhupo deposit. The conjugate joints and inter-bedding fractures in the limb of the Wuxu anticlinorium controlled the branching veinlets and stratiform, paleokarst infilled ores in the Bawang deposit. The post-ore EW-striking faults are not obvious and displaced preceding two-phase structures and ores. Three primary paragenetic stages of hydrothermal process have been recognized: (I) Sphalerite dominated + massive pyrrhotite with euhedral pyrite porphyroblasts, (II) Cassiterite + siderite + arsenopyrite dominated with minor scheelite + quartz + fluorite, and (III) Jamesonite + stibnite + sulfosalt + carbonates. Cassiterite U-Pb dating provided a lower intercept age of 90.2 +/- 3.1 Ma and 90.6 +/- 4.6 Ma for the Jianzhupo and Bawang deposits, respectively. These two ages are consistent with the chronological data of tin-sulfides and orerelated felsic intrusions in the Danchi fold-and-thrust belt, South China. Our studies coupled with previous gravity data suggests a distal magmatic-hydrothermal infilling tin-polymetallic district and indicates that the Wuxu district has great potential for additional tin mineralization.