Ore Geology Reviews最新文献

{"title":"Distribution and enrichment processes of cobalt in the Longqiao iron skarn deposit in Eastern China","authors":"Yifan Zhang ,&nbsp;Yu Fan ,&nbsp;Yinan Liu ,&nbsp;Taofa Zhou ,&nbsp;Bangguo Ou","doi":"10.1016/j.oregeorev.2024.106277","DOIUrl":"10.1016/j.oregeorev.2024.106277","url":null,"abstract":"<div><div>Longqiao is a cobalt-rich skarn iron deposit in Eastern China. As a typical representative of its type, it provides an opportunity to study the occurrence, distribution, and factors controlling cobalt in these deposits. Cobalt-bearing ores in Longqiao deposit can be classified into two types: cobalt-bearing diopside-magnetite ore (Co-Di-Mag) and cobalt-bearing phlogopite-magnetite ore (Co-Phl-Mag). Systematic whole-rock geochemical analysis, automated mineral analysis (TESCAN Integrated Mineral Analyzer, TIMA), and LA-ICP-MS trace element analysis were conducted on the two ore types. Three independent cobalt minerals（cobaltite, glaucodot, and carrollite）were found in Co-Di-Mag; no independent cobalt minerals were found in Co-Phl-Mag. TIMA and LA-ICP-MS analyses showed that cobalt in Co-Phl-Mag is mainly hosted in pyrite, so the pyrite content has a decisive role in the overall cobalt content. Cobalt in Co-Di-Mag is controlled by the content of magnetite, pyrite, and cobalt minerals.</div><div>In both the diopside-magnetite stage (Stage I) and phlogopite-magnetite stage (Stage II), the cobalt mainly occurs in magnetite, and its content gradually decreases from 80 to 30 ppm as the system evolved. During the sulfide stage, minor pyrite deposited near the intrusion, and cobalt occurs in the pyrite lattice and also forms numerous independent cobalt minerals. Pyrite is abundant in the distal part of the ore-body, where all cobalt occurs in pyrite, and independent cobalt minerals are absent.</div><div>Cobalt mainly occurs in pyrite in Longqiao deposit, which is favorable for beneficiation and recovery. Similar skarn iron deposits are widespread in eastern China, and the cobalt in these deposits has potential for recovery.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"174 ","pages":"Article 106277"},"PeriodicalIF":3.2,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142444746","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":"Mineralization processes in the Bainaimiao Cu-Au deposit in Inner Mongolia, China: Constraints from geology, geochronology, and mineralogy","authors":"Changhao Li ,&nbsp;Ping Shen ,&nbsp;Branimir Šegvić ,&nbsp;Pei Li ,&nbsp;Chong Cao ,&nbsp;Ge Ma ,&nbsp;Qingyu Suo ,&nbsp;Haoxuan Feng ,&nbsp;Xiangkai Chu","doi":"10.1016/j.oregeorev.2024.106276","DOIUrl":"10.1016/j.oregeorev.2024.106276","url":null,"abstract":"<div><div>The Central Asian Orogenic Belt underwent complex tectonic processes and is one of the most intensely accretionary areas globally. Porphyry copper deposits within the belt were likely subjected to deformation during tectonic processes. The Bainaimiao Cu-Au deposit is a typical example of a deformed porphyry deposit whose formation processes include a porphyry emplacement (Event I), a greenschist facies metamorphism (Event II), and a brittle deformation (Event III). Geochronology and trace element geochemistry of zircon, volatiles of magmatic apatite, along with the assemblages, textures, abundances, and compositions of phyllosilicates from these three events were investigated to unveil the physicochemical conditions under which the key geological events relevant to the deposit formation took place. LA-ICP-MS zircon U-Pb dating shows that the granodiorite porphyry in the northern and southern zones formed at 447.4 ± 1.6 to 445.8 ± 3.6 Ma and 436.1 ± 3.8 to 434.1 ± 3.3 Ma, respectively. The granodiorite porphyry in the northern zone has higher oxygen fugacity and Cl_melt content but similar S_melt and F_melt contents compared to the granodiorite porphyry in the southern zone. Microscopic and mineralogic observations point to Event I to be of high plagioclase (22–67 vol%) and quartz (6–40 vol%) content with a range of hydrothermal minerals related to potassic, phyllic, and propylitic alterations. Event II features high amphibole (38–83 vol%) or epidote-chlorite (up to 77 vol%) content with minerals precipitating along the schistosity planes. Event III is characterized by wide veins (3–80 cm) and the highest quartz (61–65 vol%) and calcite (12–19 vol%) content. Geothermometry results show the temperature of potassic and phyllic alterations of Event I to be ∼622 °C and ∼288 °C, respectively. Based on geothermometry and <em>P-T</em> pseudosections, the temperatures of metamorphism and metallic precipitation of Event II were ∼271–634 °C and 297–328 °C, respectively. Both mechanical and chemical mobilization of metallic elements results in Cu mineralization during Event II. The metallic precipitation temperatures of Event III spanned from 297 to 328 °C according to chlorite geothermometry. The ratios of Fe³⁺/Fe_total and Mg/(Mg + Fe_total) of biotite, chlorite Fe/(Fe + Mg), and white K-mica composition show the mineralizing fluid of Event III to be the most oxidized while that of Event II is the most reduced, F-rich and features the lowest water/rock ratio. This study suggests that deformation processes can increase the Cu mineralization grade of the deformed porphyry deposits through mobilization and re-precipitation of metallic elements.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"174 ","pages":"Article 106276"},"PeriodicalIF":3.2,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142437638","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":"Pyrite in-situ Fe–S isotope constraints on the ore-forming sources and mineralization processes of gold and polymetallic deposits in the Liaodong Peninsula, North China Craton","authors":"Lei Xu ,&nbsp;Jin-Hui Yang ,&nbsp;Qing-Dong Zeng ,&nbsp;Hao Wang ,&nbsp;Lie-Wen Xie","doi":"10.1016/j.oregeorev.2024.106274","DOIUrl":"10.1016/j.oregeorev.2024.106274","url":null,"abstract":"<div><div>Plenty of gold and polymetallic deposits are widespread in the eastern part of the North China Craton. They are associated with mafic to felsic dikes and hosted by Precambrian basement or Mesozoic granitoids. However, the sources of gold and other metals in the ore-forming fluids remain controversial. Here we present in-situ S and Fe isotopes and trace element contents of pyrites from various gold and Pb–Zn–(Ag) deposits in the Liaodong Peninsula, China. Pyrites from quartz vein-type gold deposit hosted by Mesozoic granites in the Wulong deposit have relatively homogeneous magmatic-like S isotopes (δ³⁴S values of 0.9 ‰ to 2.5 ‰) and Co/Ni ratios, indicating derivation of sulfur and, by inference, of ore fluids/materials most likely from Mesozoic magmas. In contrast, pyrites from gold and Pb–Zn–(Ag) deposits in the Qingchengzi orefield hosted by Precambrian basement have high and variable δ³⁴S values (9.7 ‰ to 12.7 ‰ for the Wandigou altered rock-type gold deposit and 4.7 ‰ to 8.5 ‰ for the Xiquegou Pb–Zn deposit and the Zhenzigou Pb–Zn–Ag deposit), identical to those of host rocks, indicating the important contributions of gold and other metals from wall rocks to the ore deposits. Pyrites from the various deposits have variable δ⁵⁶Fe values of 0.08 ‰ to 0.63 ‰ for the Pb–Zn–Ag deposit, –0.58 ‰ to 1.23 ‰ for the altered rock-type gold deposit, and –0.68 ‰ to 0.77 ‰ for the quartz vein-type gold deposit, indicating distinct mineralization processes. Rapid precipitation of pyrites (with negative δ⁵⁶Fe values) in the alteration rock and subsequent deposition of pyrites (with positive δ⁵⁶Fe values) from the residual fluids in an Fe-open hydrothermal system during intensive ore-forming fluid-wall rock interaction account for the Pb–Zn–Ag mineralization, while weak fluid-rock interaction and pyrites precipitation from a Fe-closed hydrothermal system contribute to gold mineralization. Our observations provide a robust Fe–S isotope evidence for the contribution of various sources and metallogenic processes for distinct gold and polymetallic deposits.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"173 ","pages":"Article 106274"},"PeriodicalIF":3.2,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422243","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":"Mineral prospectivity mapping susceptibility evaluation based on interpretable ensemble learning","authors":"Zhengbo Yu ,&nbsp;Binbin Li ,&nbsp;Xingjie Wang","doi":"10.1016/j.oregeorev.2024.106248","DOIUrl":"10.1016/j.oregeorev.2024.106248","url":null,"abstract":"<div><div>In the present study, an interpretable ensemble learning-based method for mineral prediction mapping is proposed to address the limitations of traditional mineralization prediction modeling. A stacking ensemble learning model was constructed, employing random forest (RF), extreme gradient boosting (XGBoost), and AdaBoost as primary learners, and logistic regression as the secondary learner. The model’s interpretability was analyzed using local interpretable model-agnostic explanations (LIME) and shapley additive explanations (SHAP) algorithms. The lead–zinc deposits in the Changba mining area of Gansu Province served as a case study. By integrating geological and geochemical data, and selecting 18 evaluation factors, the effectiveness and interpretability of the ensemble learning model in mineralization prediction were validated. The results demonstrate that the lead–zinc prospecting map generated using the stacking model effectively correlates geological and geochemical data with known lead–zinc deposit locations, significantly enhancing the accuracy of identifying potential lead–zinc prospecting areas.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"173 ","pages":"Article 106248"},"PeriodicalIF":3.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142359149","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":"Geochemical and Sr-Nd isotopic implications for the petrogenesis of the late Silurian Shitoukengde mafic–ultramafic intrusion in the East Kunlun Orogen, NW China","authors":"Wen Chen ,&nbsp;Lie-Meng Chen ,&nbsp;Song-Yue Yu ,&nbsp;Da-Peng Li ,&nbsp;Jian Kang ,&nbsp;Hua-Liang Huang ,&nbsp;Shu-Kuan Wu ,&nbsp;Zhi-An Wang","doi":"10.1016/j.oregeorev.2024.106264","DOIUrl":"10.1016/j.oregeorev.2024.106264","url":null,"abstract":"<div><div>The Shitoukengde mafic–ultramafic intrusion is the host of the second-largest sulfide deposit after the Xiarihamu Ni-Co deposit in the East Kunlun Orogenic Belt (EKOB), northern Tibet Plateau, China. Despite several studies, the age, petrogenesis, and the cause of low Ni-tenor for this intrusion remain poorly constrained. In this study, zircons separated from the pyroxenite at Shitoukengde yield a SHRIMP U-Pb age of 418.9 ± 3.1 Ma, corresponding to the widespread magmatism of the late Silurian to early Devonian in the EKOB. Whole-rock major and trace element compositions indicate that fractional crystallization played a key role in controlling the magma composition and element distribution within the intrusion. Mafic-ultramafic rocks of the intrusion, particularly peridotite, have highly variable and exceptionally elevated (⁸⁷Sr/⁸⁶Sr)_i and negative ɛ_Nd(t) values. Some samples from the Shitoukengde intrusion exhibit initial Sr-Nd isotope ratios that overlap with those from the Xiarihamu intrusion, while others (e.g., peridotite) display higher (⁸⁷Sr/⁸⁶Sr)_i values than those observed in the latter. The unusual Sr-Nd isotopic compositions of the Shitoukengde intrusion could be attributed to the assimilation of Mg-rich carbonate within a deep-seated magma chamber. This contamination process facilitates the crystallization of olivine, consequently reducing Ni content in residual magma. Furthermore, the contamination of Mg-rich carbonate may promote oxygen fugacity and thus enhance the solubility of sulfur while restricting the sulfide saturation in the magma. We thus propose that the extensive contamination of Mg-rich carbonate is a key factor contributing to the relatively low Ni-tenor observed at Shitoukengde.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"173 ","pages":"Article 106264"},"PeriodicalIF":3.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422363","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":"Genesis studies of Li–Rb deposits in pegmatites from Bailongshan, western China: Evidence from chronology, fluid inclusions, and H–O isotope analysis","authors":"Wei Wang ,&nbsp;Wei Liu ,&nbsp;Xiaofei Du ,&nbsp;Zongquan Yao ,&nbsp;Lingling Gao ,&nbsp;Yong Li ,&nbsp;Chuan Chen ,&nbsp;Huadong Ma ,&nbsp;Zhengle Chen ,&nbsp;Libo Wang","doi":"10.1016/j.oregeorev.2024.106255","DOIUrl":"10.1016/j.oregeorev.2024.106255","url":null,"abstract":"<div><div>The Bailongshan Pegmatite deposit, located in the West Kunlun Orogenic Belt, Northwest China, is a newly discovered, super-large Li–Rb (Be–Ta–Nb) rare-metal deposit. Since complex magmatic-hydrothermal processes are responsible for the mineralization of such rare-element pegmatites, it is desirable to study the evolution and sources of ore-forming fluids to analyze the genesis of ore deposits. In this study, the ⁴⁰Ar/³⁹Ar plateau ages of muscovite and biotite were determined to be 171.36 ± 1.87 and 172.39 ± 1.66 Ma, respectively, indicating that the duration of hydrothermal mineralization was approximately 170 Ma. Based on the zonal nature of the mineral assemblage, the Bailongshan area was divided into four zones and stages (I–IV), namely the albite–quartz–lithium tourmaline (AQT, stage I), albite–quartz-bearing mica (AQM, stage II), albite–quartz–spodumene (AQS, stage Ⅲ), and spodumene–quartz (SQ, stage IV) zones. Among these, AQS and SQ were the main ore-bearing areas. In terms of the fluid inclusions found in quartz and spodumene, the different types include a gas-rich phase (V-type), a liquid-rich phase (L-type), a daughter mineral-bearing three-phase (S-type), and a carbon dioxide-bearing phase (C-type). In stage I, the homogeneous temperatures of the V- and S-type fluid inclusions varied from 365 to 415 °C, while their corresponding salinities were 8.5–12.9 and 44.8–47.2 wt% NaCl equiv., respectively. In stage II, the homogeneous temperature and salinity of the L-type inclusions were 315–365 °C and 9.9–13.3 wt% NaCl equiv., respectively, while in stages Ⅲ and IV, the homogeneous temperatures of the L- and S-type fluid inclusions were between 235 and 335 °C, while their salinities were 7.2–12.3 and 32.1–37.0 wt% NaCl equiv., respectively. Furthermore, for the C-type inclusions, the homogeneous temperature and salinity were 235–320 °C and 4.9–10.6 wt% NaCl equiv., respectively. The laser Raman results showed that the fluid in the metallogenic stage was an H₂O–NaCl–CO₂–CH₄ system. Based on the homogeneous temperature and salinity results, the fluid capture pressure from stage III to stage IV was calculated to be 280–150 MPa, and the depth of the capture was &gt;6 km. Moreover, the H–O isotope results suggested that the early ore-forming fluids are mainly magmatic hydrothermal fluids, whereas the later (stage IV) mineralizing fluids may be mixed with a small amount of meteoric water. The subsequent immiscibility of the fluid may be one of the factors responsible for the discharge and precipitation of minerals.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"173 ","pages":"Article 106255"},"PeriodicalIF":3.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142359147","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":"Tetrahedrite-(Hg) from the Litija deposit, Central Slovenia: Mineral chemistry insights into fluid evolution processes","authors":"Aleš Šoster ,&nbsp;Federica Zaccarini ,&nbsp;Janez Zavašnik","doi":"10.1016/j.oregeorev.2024.106272","DOIUrl":"10.1016/j.oregeorev.2024.106272","url":null,"abstract":"<div><div>For over a century, the main carrier of Silver in the Litija mineralisation has been debated, with fine-grained galena often identified as the primary host. The <em>in-situ</em> quantitative microanalysis of a silver-bearing ore from the Alma orebody reveals that silver is not hosted within the galena but occurs instead as inclusions within tetrahedrite-(Hg). The mechanism of silver incorporation in tetrahedrite is complex and may occur through atom-to-atom substitution, where monovalent silver replaces monovalent copper (Ag⁺ ↔ Cu⁺). Additionally, silver can be present as a separate phase, either as nanoscale inclusions of acanthite or through the replacement of pre-existing silver-rich chalcopyrite. Elemental correlations and minor variations in the element distribution within the studied tetrahedrite provide insights into the chemistry of the mineralizing fluid. These findings suggest an initial reducing, near-neutral, low-chlorinity fluid promoting incorporation of Sb³⁺ and Hg²⁺ into tetrahedrite. This fluid subsequently mixed with high-salinity, Cl-rich, near-neutral fluid transporting Zn²⁺. Sulfide precipitation introduced additional acidity in the mixed fluids, altering the pH and promoting As³⁺ and Zn²⁺ incorporation into tetrahedrite. We suggest that Hg²⁺ ↔ Zn²⁺ substitution in tetrahedrite is influenced by pH fluctuations and fluid mixing. These findings provide new insights into the geochemical processes governing trace element incorporation in sulfosalt minerals and offer valuable framework for understanding mineralization in similar hydrothermal systems worldwide.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"173 ","pages":"Article 106272"},"PeriodicalIF":3.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422244","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":"Petrogenesis and tectonic evolution of mineralized mafic intrusions in the Eastern Desert of Egypt: Implications for gold–sulfide genesis","authors":"Mohamed Zaki Khedr ,&nbsp;Mohamed H. Ghoneim ,&nbsp;Wael Hagag ,&nbsp;Christoph Hauzenberger ,&nbsp;Akihiro Tamura ,&nbsp;Yuji Ichiyama ,&nbsp;Eiichi Takazawa ,&nbsp;Ali Y. Kahal ,&nbsp;Kamal Abdelrahman ,&nbsp;Sara Zamzam ,&nbsp;Tomoaki Morishita ,&nbsp;Amr El-Awady","doi":"10.1016/j.oregeorev.2024.106273","DOIUrl":"10.1016/j.oregeorev.2024.106273","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The whole–rock chemistry, mineral chemistry, and remote sensing data of the Atud–Um&lt;!--&gt; &lt;!--&gt;Khasila Neoproterozoic mafic intrusions in the Eastern Desert of Egypt show two different mafic plutons: (1) the metagabbro–diorite complex; and (2) the G. Atud gabbros. Both of these contain two types of Cu–Ni–Fe–sulfide mineralizations. Multispectral remotely sensed images of Landsat 8 OLI/TIRS, Sentinel 2–B, and ASTER1T were used to give an overview of hydrothermal alteration signatures and distinguish different lithological units. The G. Atud gabbros are intruded into the metagabbro–diorite complex and consist mainly of olivine gabbros, while the metagabbro–diorite complex comprises metagabbros, diorites, and quartz diorites. They were formed under high &lt;em&gt;fO&lt;sub&gt;2&lt;/sub&gt;&lt;/em&gt; (ΔFMQ= +1.43 to + 0.33) with a higher crystallization temperature (∼ 900–1100 °C) and pressure (∼ 6.0 kbar on average) at 18 km depth relative to associated metagabbros. Like magmatic sulfides in mafic intrusions, the G. Atud gabbros contain disseminated grains of pyrrhotite, pentlandite, chalcopyrite, and pyrite, up to 5 vol%. On the other hand, sulfide deposits (up to 30 vol%) such as pyrite, As–bearing pyrite, arsenopyrite, and gold with minor sphalerite and galena at the Atud gold mine, are related to the metagabbro–diorite intrusion. They are found as disseminations, patches, microveinlets, and bands. The sulfide deposits and economic gold are spatially concentrated in smoky quartz veins (up to 25 g/t) and metasomatic alteration zones, i.e., silicification and hematization of metagabbros (0.32 g/t), phyllic, argillic, and propylitic alteration, and carbonate–silicified zones, along gabbroic intrusive contacts, which all follow the Najd NW–SE shear zone. They are possibly of hydrothermal origin (epigenetic). They are also precipitated by mineralized fluids (rich in Si, K, Fe, Pb, Ag, Au, As, S, Ni, Zn, Cu, CO&lt;sub&gt;2&lt;/sub&gt;, and H&lt;sub&gt;2&lt;/sub&gt;O) that have been derived from a mixed magmatic–metamorphic source. The high Au contents with As–bearing pyrite and arsenopyrite in both Fe–rich and smoky quartz veins are related to the interaction between Fe from metagabbro–diorites and the Au(HS)&lt;sup&gt;-2&lt;/sup&gt; compound as well as the crystallization of pyrite, which reduced the sulfur contents in the mineralized fluids and hence led to gold precipitation. The late intrusion of G. Atud gabbros into metagabbro–diorite rocks enhanced the circulation of sulfide-gold-bearing hydrothermal fluids towards the contacts of the latter ones. These fluids along the shear zones cause metasomatic alteration in addition to leaching and the collection of sulfides and gold in the metagabbros. The protoliths of metagabbro–diorite rocks have a calc–alkaline nature and were formed in a volcanic arc setting, while the G. Atud gabbros were crystallized from Mg-rich tholeiitic melts in the extensional rift (e.g., rifted arc) setting as a result of asthenospheric upwelling due to the slab detachment an","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"173 ","pages":"Article 106273"},"PeriodicalIF":3.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422421","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 overprints and mineralization of the Zhuguangshan granite-related U district in China: Recorded by cathodoluminescence textures and chemistry of quartz","authors":"Shen Gao ,&nbsp;Yongjian Wang ,&nbsp;Xinyu Zou ,&nbsp;Edward L. Vinis ,&nbsp;Liangliang Huang ,&nbsp;Yi Tao ,&nbsp;Jing Xu ,&nbsp;Kezhang Qin ,&nbsp;Zhengjie Qiu","doi":"10.1016/j.oregeorev.2024.106256","DOIUrl":"10.1016/j.oregeorev.2024.106256","url":null,"abstract":"<div><div>Most high-grade U ores are mined from quartz veins hosted in granites. The veins formed at shallow depths during episodic hydrothermal activity, however, the evolution of multiple stage fluids is not well constrained. In this study, we collected 56 quartz samples from the world-class, granite-related, Zhuguangshan U district (&gt;17,000 t U from seven deposits) in southern China. Their textures and compositions were analyzed using scanning electron microscope cathodoluminescence (SEM-CL, <em>n</em> = 98) and laser ablation-induction coupled plasma-mass spectrometry (LA–ICP–MS, <em>n</em> = 643). Four types of quartz were identified, including magmatic quartz, early hydrothermal euhedral quartz, ore stage hydrothermal quartz (U-rich), and late hydrothermal quartz. New quartz textures and chemical compositions show that the transition of early hydrothermal quartz from the magmatic to hydrothermal stages is discontinuous, unlike the continuous trend observed in most magmatic-hydrothermal systems. Ore stage quartz is CL dark (with a peak at 650 nm), occurs as rims on early barren quartz, and has high contents of Mn, Al, and Sb. Altered textures of magmatic quartz developed through fluid-rock reactions at low temperatures, while rimmed textures of hydrothermal quartz formed during subsequent late-stage U-bearing fluid events, which played a crucial role in U mineralization. Quartz in the Zhuguangshan U district has distinct features compared to other magmatic-hydrothermal systems that can guide exploration for high-grade ore in this, and perhaps other, granite-related U systems.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"173 ","pages":"Article 106256"},"PeriodicalIF":3.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422364","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":"Combining categorical boosting and Shapley additive explanations for building an interpretable ensemble classifier for identifying mineralization-related geochemical anomalies","authors":"Yongliang Chen ,&nbsp;Bowen Chen ,&nbsp;Alina Shayilan","doi":"10.1016/j.oregeorev.2024.106263","DOIUrl":"10.1016/j.oregeorev.2024.106263","url":null,"abstract":"<div><div>The vast majority of shallow and deep learning techniques used to identify mineralization-related geochemical anomalies are black-box algorithms that lack the ability to elucidate the individual contributions of each element towards the model predictions. In addition, most of the anomaly identification models established by both shallow and deep learning algorithms lack robustness. Establishing interpretable and robust machine learning models is a challenge in applying machine learning techniques to geochemical anomaly identification. To this end, the categorical boosting (CatBoost) algorithm was employed to build a robust ensemble classifier to identify mineralization-related anomalies from the 1:50,000 geochemical reconnaissance data (stream sediment survey) in the Yeniugou area of Xinjiang (China). The receiver operating characteristic curve (ROC) and precision-recall (P-R) curve of the ensemble model were plotted, and the area under the ROC curve (AUC) as well as the area under the P-R curve (AUPRC) of the ensemble model were calculated to measure the performance of the ensemble model. The ROC curve of the ensemble model approximates that of the perfect classification model. The P-R curve of the ensemble model is close to the upper right corner of the P-R space. The AUC and AUPRC values of the ensemble model reaches 0.9981 and 0.7816, respectively. The identified polymetallic mineralization-related geochemical anomalies account for 3% of the whole exploration area, correctly identifying all known polymetallic deposits. To enhance the interpretability of the CatBoost model, the Shapley additive explanations (SHAP) tool was adopted to graphically interpret the predictions of the ensemble model. The graphic interpretation shows that the importance order of the 14 elements is Ni-Au-Ag-Sn-As-Cr-Zn-Cu-Pb-Sb-W-Bi-Mo-Co. Cu and Ni are most likely metallogenic elements of the study area. Cu interacts with Ni, Ag, As, Sn, Cr, Zn, Pb, Sb, W, Bi, and Co; and Ni interacts with Au, Sn, As, Zn, Cu, W, Bi, and Co. Two polymetallic prospective areas were delineated in the study area. One is Cu-Ni-polymetallic mineralization prospective area, and the other is Ni-polymetallic mineralization prospective area. It can be concluded that the combination of CatBoost and SHAP is an effective way to construct an interpretable ensemble model with high-performance and robustness in identifying mineralization-related geochemical anomalies.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"173 ","pages":"Article 106263"},"PeriodicalIF":3.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422422","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}