Ore Geology Reviews最新文献

{"title":"Advanced soil-gas geochemical exploration methods for orogenic gold deposits: A case study of Chalapu deposit, Xizang","authors":"","doi":"10.1016/j.oregeorev.2024.106226","DOIUrl":"10.1016/j.oregeorev.2024.106226","url":null,"abstract":"<div><p>Orogenic gold deposits play a significant role in the world’s gold reserves, and their distinctive characteristics pose challenges for exploration. The low sulfide content and narrow, fault-controlled sulfide-quartz veins hinder the use of traditional mineral exploration methods to locate deeply buried ore bodies, particularly in regolith-covered areas. Enhanced methods are required to detect deposits at greater depths. Soil gas composition shows promising potential for mineral exploration by conveying information about sulfur-rich and carbon-rich gases related to deep-seated mineralization into surface soils. However, the prospects of this method for gold deposits remain uncertain. In this study, a novel method was introduced to perform an integrated H₂S, SO₂, CH₄, and CO₂ soil-gas geochemical survey on gold ore bodies of different scales at the Chalapu deposit in Tibet. The results unveiled notable gas geochemical anomalies of H₂S, SO₂, CH₄, and CO₂ above the multi-layered or thick gold ore bodies. For instance, on exploration line 16 at point A1607, H₂S reached the regional maximum value of 1.064 ppm, coinciding with the surface exposure of the thickest gold ore body, measuring 19.81 m. While the presence of CH₄ and CO₂ anomalies alone may not signify potential mineralized zones, the combined presence of anomalous H₂S and SO₂ values along with CH₄ and CO₂ concentrations appears to be effective in identifying mineralization. These combinations of geochemical anomalies not only uncover concealed ore bodies, but also delineate the trend and extension direction in strike and dip of ore bodies. Gas intensity may provide insights into the scale of the ore bodies, with stronger gas anomalies observed in areas with thicker ore bodies at similar depths. Thus, the study reveals that soil-gas exploration shows great promise as an exploration technique for orogenic gold deposits, especially in areas with regolith cover hindering traditional methods from detecting mineralized zones for gold exploration.</p></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0169136824003597/pdfft?md5=e846cbdda7026a64a7f9c2484bb529b8&pid=1-s2.0-S0169136824003597-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142163477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Alteration and mineralization of the giant Pulang porphyry Cu–Au deposit, southwest China: Evidence from biotite mineralogy","authors":"","doi":"10.1016/j.oregeorev.2024.106222","DOIUrl":"10.1016/j.oregeorev.2024.106222","url":null,"abstract":"<div><div>The Pulang porphyry Cu–Au deposit is the largest Indosinian porphyry Cu deposit in the Geza porphyry belt. Magmatic and hydrothermal biotite crystals are widely distributed across ore bodies in the central part of the deposit. Determining the compositions of these biotite crystals can help us to understand the ore-forming fluids and processes. Here we present chemical analyses of biotite from samples collected from the ZK0406 borehole, which traverses the center of the ore bodies and the various alteration zones. We identified three types of biotite (types<!--> <!-->I, II, and<!--> <!-->III). Type<!--> <!-->I biotite is primary magmatic biotite and is surrounded by limited chalcopyrite. Type<!--> <!-->II biotite is alterated biotite surrounded by chalcopyrite and pyrite. The edges and cleavage planes of type<!--> <!-->II biotite are commonly replaced by chlorite. Type<!--> <!-->III biotite is hydrothermal biotite distributed in porphyries along fissures and is associated with large amounts of chalcopyrite and pyrite. All three biotite types are Mg-biotite. Geothermometer and oxybarometer results using the compositions of the type<!--> <!-->I biotite crystals suggest that the magmas in the Pulang deposit had temperatures of 720–766 °C and oxygen fugacities of FMQ+2.3 to FMQ+3.2. The melt/fluid fugacities estimated using the compositions of the three biotite types suggest that the fluids present during the Potassic alteration stage may have had the high transport capacity for Cu and Au in the Pulang deposit. As a result of alteration, Al and Fe were enriched in the type<!--> <!-->I biotite, whereas Si, Ti, Mg, and Na were leached, then foremed type II biotite. Type<!--> <!-->III biotite crystals have high Cu and K contents and formed during Potassic alteration. Combining these data with field observations suggests that the Cu enrichment was closely related to the type<!--> <!-->II and III biotite, which formed during the potassic–silicate alteration stage; i.e., the major ore-forming stage of the Pulang deposit.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142320326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fluid evolution of the Nulasai Cu deposit, Xinjiang, NW China: Evidence from fluid inclusions and O-H-C isotopes","authors":"","doi":"10.1016/j.oregeorev.2024.106220","DOIUrl":"10.1016/j.oregeorev.2024.106220","url":null,"abstract":"<div><p>The Nulasai deposit is the earliest Cu mine in Xinjiang, NW China, and has been mined and smelted since the warring state period. Another striking characteristic of the deposit is the high-grade (ave. 1.34 % Cu) with bornite, chalcopyrite and chalcocite as main ore minerals. Through a field and petrographic investigation, three phases of hydrothermal evolution have been recognized at the Nulasai Cu deposit, including the stage I magnetite – quartz ± chalcopyrite ± bornite veins, the stage II calcite – barite ± chalcopyrite ± chalcocite ± pyrite ± bornite veins, and the stage III calcite – barite ± chalcopyrite ± sphalerite ± pyrite ± galena veins. Fluid inclusions of the stage I veins were captured under two-phase condition indicates that existence of both contemporaneous daughter mineral-bearing and liquid-rich fluid inclusions; they have an intermediate-high salinity (11.5 ∼ 38.5 wt% NaCl equiv) and homogenization temperature (266 ∼ 376 °C), with entrapment pressures from 47 to 167 bar (depth of approximately 0.5 to 1.7 km). The coexistence of vapor-rich and liquid-rich fluid inclusions was a defining feature of the stage II fluid inclusions, and they have an intermediate salinity (6.2 ∼ 10.7 wt.%NaCl equiv) and homogenization temperature (211 ∼ 287 °C), with entrapment pressures from 18 to 70 bar (depth of approximately 0.2 to 0.7 km). Fluid inclusions of the stage III veins were captured under two-phase condition, and intermediate-low salinity (3.2 ∼ 9.2 wt.%NaCl equiv) and homogenization temperature (155 ∼ 241 °C), with entrapment pressures of 6 to 32 bar (depth of 0.1 to 0.6 km). According to the stable isotope (O-H-C) data for the three mineralization phases, magmatic water containing organic carbon made up the majority of the early ore-forming fluids, whereas abundant meteoric water has been involved during the late stage of mineralization. Therefore, we suggest that fluid mixture between magmatic water and meteoric water may have led to simultaneous decrease of fluid temperature, salinity and their stable isotope values, and finally facilitates the Cu ore precipitation. This study emphasizes how high-grade Cu deposition in orogenic belts is initiated by fluid dilution.</p></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0169136824003536/pdfft?md5=bddde4a4e8a5b850e7688236d3cc4dbe&pid=1-s2.0-S0169136824003536-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142163576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The occurrence and enrichment of cobalt in skarn Pb-Zn deposits: A case study of the Niukutou Co-rich deposit, East Kunlun metallogenic belt, western China","authors":"","doi":"10.1016/j.oregeorev.2024.106210","DOIUrl":"10.1016/j.oregeorev.2024.106210","url":null,"abstract":"<div><p>The East Kunlun orogenic belt is one of the most important Co-rich polymetallic metallogenic belts in China. Niukutou, a typical Pb-Zn-(Fe) skarn deposit, is situated within the marble formations of the Ordovician-Silurian Qimantagh Group in this belt. Six distinct stages of mineralization have been identified: (1) prograde skarn stage, (2) hydrous mineral-oxide stage, (3) pyrrhotite stage, (4) chalcopyrite stage, (5) sphalerite-galena stage, and (6) carbonate stage. Co enrichment predominantly manifests at chalcopyrite stage, with two distinct Co minerals identified: glaucodot and cobaltite. Co is also present as isomorphous substitution in sulfides (mostly arsenopyrite) and as inclusions in chalcopyrite. Variations in As and S contents in arsenopyrite suggest a steady decrease in ore-forming fluid temperature from the pyrrhotite stage to sphalerite-galena stage. Variations in the Co, Ni, Se, As, Sb, Cu, Sn, Ag, and Zn contents in pyrite indicate fluctuations in temperature, oxygen fugacity, and fluid composition during ore formation. Sulfur isotope compositions (δ³⁴S) through the pyrrhotite stage to the sphalerite-galena stages show a limited range from +3.4 to +7.0 ‰, suggesting a predominantly magmatic source. Whereas, the δ³⁴S of pyrite and marcasite in carbonate stage exhibit significant variations from −22.5 to +22.7 ‰. We propose that this significant variation may be caused by mixing of sulfur from the surrounding rocks and the large fluctuations in oxygen fugacity due to the influx of meteoric water at the carbonate stage. Overall, Co in Pb-Zn skarn system may occur either as independent minerals or as lattice substitution in sulfides such as arsenopyrite. The deposition of Co-bearing minerals is related to decreases in temperature and <em>f</em>O₂ during the chalcopyrite stage.</p></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0169136824003433/pdfft?md5=47afabf606f049637756d17d7480b699&pid=1-s2.0-S0169136824003433-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142128386","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"In situ Cu isotopes reveal the mechanism of Sn-Cu mineralization: A case study from the Jinkeng deposit, South China","authors":"","doi":"10.1016/j.oregeorev.2024.106217","DOIUrl":"10.1016/j.oregeorev.2024.106217","url":null,"abstract":"<div><p>This study presents high-resolution <em>in situ</em> Cu isotope data for chalcopyrite from the Jinkeng Sn-Cu deposit, Guangdong Province, China, with the aim of understanding how the Sn-Cu mineralization was formed. Results show that early chalcopyrite (quartz-cassiterite stage) has the lowest δ⁶⁵Cu values (–0.01 to +0.02 ‰), similar to δ⁶⁵Cu values (∼0‰) in most granites. In contrast, chalcopyrite from the subsequent cassiterite-sulfide stage exhibits the highest δ⁶⁵Cu values (+0.90 to +0.97 ‰), comparable to those of the volcanic country rocks (+0.87 to +1.00 ‰). δ⁶⁵Cu values in late chalcopyrite gradually decrease (from +0.79 to +0.45 ‰) across the latest ore-forming stages, from quartz-sulfide to quartz-calcite-sulfide mineral assemblages. Observed variation in δ⁶⁵Cu is explained by water–rock interaction. Quantitative geochemical modeling also demonstrates that the Cu isotopic compositions of chalcopyrite record variable degrees of water/rock ratios during water–rock interactions. Therefore, our results suggest that water–rock interaction plays a critical role in providing Cu for Sn-Cu ore systems. The study further indicates that <em>in situ</em> Cu isotope analysis provides an accurate and efficient tool for diagnosis of magmatic-hydrothermal processes.</p></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0169136824003500/pdfft?md5=fa8956aa4275f728923db9d805a33788&pid=1-s2.0-S0169136824003500-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142128387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cobalt occurrence and sulfide geochemistry of the De’erni Cu-Zn-Co deposit in NW China","authors":"","doi":"10.1016/j.oregeorev.2024.106218","DOIUrl":"10.1016/j.oregeorev.2024.106218","url":null,"abstract":"<div><p>The De’erni ultramafic-hosted volcanogenic massive sulfide deposit is a large Cu-Zn-Co deposit, located in the East Kunlun Orogenic Belt, and contains 0.57 Mt Cu, 0.16 Mt Zn, 0.03 Mt Co with a 0.09 % Co average ore grade. However, cobalt occurrence and the mechanism for its enrichment are unclear. This study investigated mineralogical characteristics using the TESCAN Integrated Mineral Analyzer (TIMA), Electron Probe Microanalysis (EPMA) analyses, Laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) analyses, and in situ sulfur isotopic analysis of minerals from different stages of ores in the De’erni deposit to understand Co mineralization. Three mineralization stages were recognized, and three types of pyrite were identified: Py1, Py2, and Py3 in the De’erni deposit. Cobalt occurs as siegenite, and a significant amount of Co is found in pyrite. The EPMA results show that the highest Co content is 0.40 wt% (0.02–0.40 wt%). The LA-ICP-MS trace element data show that Py1 is enriched in Co (208–5082 ppm), Ni (13.50–836 ppm, average 212 ppm), Py2 contains 11.07–322 ppm (average 94.45 ppm) Co, Py3 has Co contents of 0.68–31.90 ppm (average 5.79 ppm). The δ³⁴S values of Py1, Py2, and Py3 range from 7.2 to 10.8 ‰, 4.6 to 6.7 ‰, 0.6 to 1.9 ‰, respectively, suggesting that the sulfur source originated from seawater-mixed magma fluids. Py1 occurs as euhedral-subhedral grains and displays oscillatory zoning, indicating a relatively unstable environment. Concentrations of Co, Ni, and As are highest in early-stage pyrite, whereas Se and Ag content gradually increased from Py1 to Py2 to Py3. The trace element data and mineral paragenesis indicate that the temperature and sulfur fugacity gradually decreased from stage 1 to 3. Furthermore, the first stage fluid is rich in Co and Ni, and the third stage fluid is rich in Ag and Se with Co and Ni depletion. These findings offer crucial insights into the De’erni deposit Co mineralization processes and evolution.</p></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0169136824003512/pdfft?md5=2ae255355929b7173aa66ac47126623c&pid=1-s2.0-S0169136824003512-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142147977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Two-stage mineralization of the Jinkeng Sn-Cu deposit in Eastern Guangdong, Southeast China: Response to magmatic activities and tectonic transformation","authors":"","doi":"10.1016/j.oregeorev.2024.106212","DOIUrl":"10.1016/j.oregeorev.2024.106212","url":null,"abstract":"<div><p>The Jinkeng Sn-Cu polymetallic deposit in South China consists of two different types of orebodies: 1) NE-striking skarn- and vein-type Cu-Pb-Zn-Sn orebodies in volcanic rocks suffering subsequent ductile shear deformation, and 2) NW-striking quartz-cassiterite-sulfide veins filled in the faults at the porphyritic granodiorite outward from the fine-grained granite which does not exhibit deformation. The relationships among Sn-Cu polymetallic mineralization, regional magmatism, and deformation metamorphism are still controversial. To address it, the geochronological, whole-rock and mineral geochemical research along with the detailed field investigation were conducted in this study. Our zircon U-Pb dating results show that the volcanic rocks formed at 158–162 Ma, earlier than the porphyritic granodiorite which yields the emplacement age of 146–147 Ma. In-situ LA-ICP-MS U-Pb dating of cassiterite from the deformed skarn ores indicates the early-stage mineralization occurred at 146 ∼ 148 Ma, which is similar to the emplacement age of the porphyritic granodiorite, but earlier than the formation of quartz-cassiterite-sulfide veins and the fine-grained granite (141∼144 Ma). Further, the whole-rock and biotite geochemistry, and zircon Hf isotope compositions suggest that the porphyritic granodiorite exhibits a lower degree of magma differentiation, higher oxygen fugacity, higher Cl and lower F contents than the fine-grained granite. The porphyritic granodiorite might provide the most Cu-Pb-Zn budget accompanied by minor Sn for early-stage mineralization. Overall, our study suggests that the Jinkeng Sn-Cu polymetallic deposit formed in two scenarios where the early dominated Cu-Pb-Zn and minor Sn mineralization related to the emplacement of the porphyritic granodiorite is superimposed by the late vein-type Sn-dominated mineralization related to the emplacement of the fine-grained granite. The two isolated mineralizing events (∼147 Ma and ∼141 Ma, respectively) in Jinkeng were probably responded to the regional magmatic activities triggered by the tectonic transformation where two extensional tectonic events were separated by a short contractional event (147–144 Ma).</p></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0169136824003457/pdfft?md5=489ee99f96d97d8261d5aae252474339&pid=1-s2.0-S0169136824003457-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142098864","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improved mineral prospectivity mapping using graph neural networks","authors":"","doi":"10.1016/j.oregeorev.2024.106215","DOIUrl":"10.1016/j.oregeorev.2024.106215","url":null,"abstract":"<div><p>Prospectivity analysis is an important part of the exploration information system (EIS) and mineral prospectivity mapping (MPM) is a widely used technique for prospectivity analysis. Despite MPM studies employing various machine learning (ML) algorithms for various purposes, MPM is still considered insufficient to capture the complexity of many important ore-forming geological processes. One potential issue concerns the difficulty with which conventional application of ML algorithms can learn from relational information. For instance, the conventional application of ML algorithms to tabular data for mineral exploration does not effectively consider spatial relations across or between geological terranes, because point data are treated as independent entities that do not influence their neighbor’s characteristics. Here, we demonstrate how re-designing exploration data into a graph format that focuses on spatial relationships can increase the effectiveness of mineral prospectivity mapping (MPM). We demonstrate that the use of graph deep learning can be beneficial when utilizing categorical and numerical exploration data. This approach was applied to three different commodities (copper, iron, and tin) in the southern United Kingdom in order to compare the effectiveness of the graph neural network (GNN) method with conventional ML techniques. We show that graph-based ML that utilizes immediate neighbor relationships in the training process significantly improves performance in three key metrics when compared to tabular data, particularly so when trained with a dataset where there are more barren (non-occurrence) data points than mineralized (occurrence) ones. To produce the most useful prospectivity maps, we recommend training a GNN algorithm by using an imbalanced training dataset comprising more barren data than mineralized data. We expect that further testing of the GNN method will lead to optimization of the supervised ML techniques used in MPM and EIS to prospect for key metal commodities in regions with incomplete geological data.</p></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0169136824003482/pdfft?md5=489985c6b1af3b4f26ac5ffba1fbdecd&pid=1-s2.0-S0169136824003482-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142147978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ages and geochemistry of garnet reveal multi-types of iron-copper mineralization in the Eastern Tianshan, NW China","authors":"","doi":"10.1016/j.oregeorev.2024.106219","DOIUrl":"10.1016/j.oregeorev.2024.106219","url":null,"abstract":"<div><p>The Aqishan-Yamansu Fe-Cu-Au metallogenic belt in the Eastern Tianshan, NW China, hosts numerous Fe and Fe-Cu deposits that may have different genetic models, such as volcanic-hosted and skarn/IOCG types. These variations in genetic models are attributed to whether the mineralization is associated with hydrothermal activity related to volcanic or intrusive rocks. This study primarily focuses on garnets formed during the early skarn alteration in the Shuanglong Fe-Cu and Shaquanzi Fe deposits within this belt. Garnets from the Shuanglong deposit can be divided into two types and exhibit general homogeneity, with SL-Grt1 being Fe-rich and subsequently replaced by the Fe-poor SL-Grt2. Garnets from the Shaquanzi deposit display complex zonation patterns, SQZ-Grt1 show core–oscillatory zoned rim and SQZ-Grt2 show core–mantle–oscillatory zoned rim. Laser-ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) dating of SL-Grt1 and SL-Grt2 produced lower intercept ²⁰⁶Pb/²³⁸U ages ranging from 318.0 ± 6.4 Ma to 303.7 ± 16.4 Ma, coinciding with the multi-stage granite occurrence. In contrast, SQZ-Grt1 and SQZ-Grt2 yielded ages between 328.0 ± 2.6 Ma and 320.4 ± 1.7 Ma, corresponding to the timing of the hosted rhyolite. SL-Grt1 show light rare earth element (LREE) enrichment, and low concentrations of high field strength elements (HFSE), such as V and Zr, and appears to have formed rapidly within an open system. Conversely, SL-Grt2 is characterized by heavy rare earth element (HREE) enrichment and elevated HFSE contents, which could be formed slowly in a closed system. The variable composition in the SQZ-Grt1 and SQZ-Grt2 record cyclical changes in fluid kinetics (vigorous fluid flow vs. fluid stagnation). The cyclical zones in SQZ-Grt2 with HREE and HFSE concentrations below the detection limit indicate multiple inputs of external seawater. The distinct characteristics between Shuanglong and Shaquanzi garnets may reflect the difference between the single magma intrusion and complex volcanic activity. Combining previously published chronological data, this study elucidates a transition from the Middle Carboniferous volcanic-hosted Fe deposits (335–320 Ma) to the Late Carboniferous intrusion-related skarn or IOCG type Fe-Cu deposits (310–300 Ma) in the Aqishan-Yamansu belt.</p></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0169136824003524/pdfft?md5=42cb953234f8a922e1bb1c114d6c4dee&pid=1-s2.0-S0169136824003524-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142136314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The magma evolutional constrains on the genesis of proximal Zn skarn mineralization: A case study from the Yaojialing deposit in Tongling district, eastern China","authors":"","doi":"10.1016/j.oregeorev.2024.106216","DOIUrl":"10.1016/j.oregeorev.2024.106216","url":null,"abstract":"<div><p>The major factors especially the roles of the magma evolution controlling the Zn/Cu mineralization in skarn deposits are still controversial. Yaojialing is a large-sized skarn Zn polymetallic deposit (1.74 Mt Zn at 3.6 %, 30.4 t Au at 4.2 g/t and 24.8 t Cu at 0.83 %) located in the Tongling district of the Middle–Lower Yangtze belt (MLYB), both the proximal and distal areas of the deposit exhibit high Zn/Cu mineralization. The intrusions in Yaojialing primarily consist of quartz monzonite porphyry (QMP) and granodiorite porphyry (GDP), and the QMP is related to skarn mineralization. Both the QMP and GDP display relatively high (⁸⁷Sr/⁸⁶Sr)_i values (0.707907 to 0.709390), low ε_Nd(t) values (−9.05 to −8.17) and negative ε_Hf(t) values (−8.51 to −11.72), suggesting that they originated from a mixed source of enriched mantle and lower crust. Both the QMP and GDP contain type I and type II amphiboles, while type III amphibole exists only in QMP. Type I amphibole is acicular crystals shape, type II amphibole is euhedral in shape and relatively large in size (0.6–2.0 mm), while type III amphibole crystallized around the margin of type II amphibole. The type I amphibole from QMP and GDP show similar calculated temperatures (948–1010 ℃), pressures (2.9–6.5 kbar, corresponding depths at 11.0 to 24.4 km), <em>f</em>O₂ (ΔFMQ = 0.2–1.9) and H₂O content (4.2–6.8 wt%). Type II amphibole crystallized at 815–941 ℃, 1.2–2.9 kbar (corresponding to depth of 4.6–11.1 km), ΔFMQ = 0.7–2.1, and 4.4–5.7 wt% H₂O. Type III amphibole have a lower temperature (679–795 ℃), pressure (&lt;0.5 kbar) and water content (2.5–4.3 wt%) but higher <em>f</em>O₂ value (ΔFMQ = 3.1–3.8) compared to type I and type II amphiboles. Reverse zoning of plagioclase and higher Mg^# (74 to 89) of type III amphibole in QMP are resulted from injection of mafic magma at shallow depths, which provide sufficient metal and favorable conditions for the formation of QMP parental magma. Modeling of magma H2O solubility indicates that QMP begins to exsolve fluid at depth of 6.2–11.1 km. Initial low oxygen fugacity and ore-forming element differential release during fluid exsolution process resulted in the high Zn/Cu mineralization at Yaojialing.</p></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0169136824003494/pdfft?md5=c922aaf94cf7bba389d7c32306f8570d&pid=1-s2.0-S0169136824003494-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142128259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}