Economic Geology最新文献

{"title":"Tungsten Mineralization in the Eastern Alps (Austria): Implications of Scheelite Trace Element Composition for Exploration Potential Evaluation","authors":"Florian Altenberger, Joachim Krause, Kai Bachmann, Julia Weilbold, Holger Paulick, Jasper Berndt, Johann G. Raith","doi":"10.5382/econgeo.5210","DOIUrl":"https://doi.org/10.5382/econgeo.5210","url":null,"abstract":"Greenfield exploration during the 1970s to 1980s has revealed tungsten enrichment in various geologic units of the Eastern Alps. This study aims to develop assessment criteria (fingerprints) for the evaluation of regional tungsten potentials in the Eastern Alps based on mineralogical and chemical criteria from 17 of these tungsten discoveries, including the world-class Felbertal tungsten deposit. Scheelite (CaWO4) is the most common tungsten mineral in the Eastern Alps and was investigated by combined cathodoluminescence imaging, electron probe microanalysis (EPMA), and in situ laser ablation-inductively coupled plasma-mass spectrometry (LAICP-MS). This approach allows the identification of three mineralization styles in the Eastern Alps: (1) intrusion-related, (2) polymetallic (As, Sb, Au), and (3) carbonate-hosted stratabound scheelite mineralization. Our results show that the trace elements Na, Sr, Nb, Mo, and total rare earth elements (ΣREE) + Y are suitable for distinguishing scheelite from different ore-forming environments. The proposed (log[Sr/Mo] vs. log[Na/Nb]) diagram facilitates the discrimination of these mineralization styles irrespective of the metamorphic overprint and reflects chemical signatures of specific ore-forming processes. The diagram provides a clear distinction of intrusion-related magmatic-hydrothermal deposits from other styles of tungsten mineralization with less promising economic potential as well as orogenic gold deposits of metamorphogenic origin. Felbertal is clearly assigned to the intrusion-related magmatic-hydrothermal deposits and differs significantly from all the other examined scheelite occurrences in the Eastern Alps. The comparison with global scheelite data sets shows that these findings have the potential to be implemented across worldwide exploration projects.","PeriodicalId":11469,"journal":{"name":"Economic Geology","volume":"5 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147371518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rare Earth Element and Yttrium (REY) Hyper-Enriched Karst Bauxites of the Mercedes-Aceitillar Mining District, Sierra de Bahoruco, SW Dominican Republic","authors":"Diego Domínguez-Carretero, Thomas Aiglsperger, Cristina Villanova-de-Benavent, Lisard Torró, Núria Pujol-Solà, Xavier Llovet, Telm Bover-Arnal, Àngel Tisora, Cristina Domènech, Australia Ramírez, Jesús Rodríguez, Bernhard Dold, Joaquín A. Proenza","doi":"10.5382/econgeo.5214","DOIUrl":"https://doi.org/10.5382/econgeo.5214","url":null,"abstract":"Rare earth elements, including yttrium (REYs), are the most sought-after among the so-called critical or strategic elements for the low-carbon energy industry. In the past decade, karst bauxite deposits have been targeted as potential nonconventional sources of these elements. The karst bauxite deposits from the Mercedes-Aceitillar mining district, classified as Fe-rich bauxites and bauxites sensu stricto, contain anomalously high REY contents oscillating between 514 and 28,787 ppm (median of 1,489 ppm), making them the most REY-enriched karst bauxites globally. Most of the samples studied are enriched in light rare earth elements (La-Nd; up to 7,449 ppm) and Y (up to 14,830 ppm). However, the most REY-enriched bauxites yield particularly high middle rare earth element (Sm-Gd; up to 4,579 ppm) and heavy rare earth element (Tb-Lu; up to 6,163 ppm) contents. In addition, the studied bauxites contain significant amounts of other critical metals, such as Sc and Ga (median of 62 and 39 ppm, respectively). The mineralogy consists predominantly of Al oxyhydroxides (mostly gibbsite), with variable amounts of Fe oxyhydroxides and kaolinite. The REY mineralogy in samples with high REY contents (>3,000 ppm) consists mainly of REY-bearing phosphates (e.g., monazite, xenotime, rhabdophane, churchite) and/or carbonates (bastnäsite group). In samples with moderate REY contents (<3,000 ppm), the main REY-bearing minerals are Al oxyhydroxides, onto which the REYs are most likely adsorbed. These findings indicate that the potential extraction of REYs and other critical metals, such as Sc and Ga, in the studied bauxites from the Mercedes-Aceitillar mining district could add, on average, an ~20% surplus to the revenue obtained from Al2O3 exploitation. The unprecedented REY contents discovered in these karst bauxites from the Dominican Republic present a unique opportunity to unravel critical metal concentration mechanisms in supergene environments and to develop new geochemical models for nonconventional REY deposits.","PeriodicalId":11469,"journal":{"name":"Economic Geology","volume":"11 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2026-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147278788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gold and Trace Element Release From Pyrite During Prograde Metamorphism of Carbonaceous Metapelites: Implications for Orogenic Gold Formation","authors":"Abdul Latheef Thathrampally, Rajarshi Chakravarti, Crystal Laflamme, Paul Olin","doi":"10.5382/econgeo.5168","DOIUrl":"https://doi.org/10.5382/econgeo.5168","url":null,"abstract":"The Neoproterozoic carbonaceous metapelites of the Mandhali Formation in the inner Lesser Himalaya contain diagenetic pyrite with above-background levels of Au (>200 ppb) when analyzed by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). These metapelites exhibit progressively metamorphosed zones (from south to north), ranging from the chlorite-muscovite zone (~372°C), to the muscovite ± biotite (~520°C) zone, to the greenschist-amphibolite transition (~570°C, >5 kbar). Within this regional framework, we document a hitherto unknown paragenesis of pyrite growth from diagenesis to peak metamorphism along with a localized phase of contact metamorphism, which predates regional metamorphism. A comparative assessment of pyrite trace element concentrations from the progressive metamorphic zones reveals that >80% of Au and ~65% of As is released from diagenetic pyrite during early chlorite dehydration at ~372°C, that is, in the chlorite-muscovite zone. Further into the muscovite ± biotite zone, at the terminal chlorite breakdown stage (480°–520°C), pyrite still occurs as the major sulfide with subordinate pyrrhotite. However, by this stage, ~93% of Au; ~75% of As; and ≥90% of Mo, Cd, Pb, Sb, W, Cu, Bi, Te, and Tl are released from pyrite. With the transition of pyrite to pyrrhotite (500°–550°C), almost all trace elements are released from pyrite into metamorphic fluids, except Co that is incorporated into the metamorphic pyrrhotite. This documented grain-scale elemental mobility is also reflected in bulk-rock Au assays; that is, mean Au of 9.8 ppb in the chlorite-muscovite zone and 1.1 ppb in the muscovite ± biotite zone. Our results suggest that pyrite recrystallization during chlorite dehydration is relatively more significant than pyrite-pyrrhotite transition in terms of Au and As release, and by extension, orogenic gold formation.","PeriodicalId":11469,"journal":{"name":"Economic Geology","volume":"35 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145674286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Depth of Magma Crystallization and Fluid Exsolution Beneath the Porphyry-Skarn Cu Deposits at Santa Rita and Hanover-Fierro, New Mexico, USA","authors":"Andreas Audétat, Jia Chang, Sean P. Gaynor","doi":"10.5382/econgeo.5197","DOIUrl":"https://doi.org/10.5382/econgeo.5197","url":null,"abstract":"The depth level at which porphyry Cu–forming magmas fractionated and exsolved mineralizing fluids is actively debated. In the classic model, extensive magma fractionation occurs in large, upper crustal magma chambers, and concomitant fluid exsolution leads to forceful expulsion of residual magmas in the form of porphyry dikes, stocks, and breccia pipes, which subsequently serve as pathways for the mineralizing fluids. In contrast, some recent studies highlighting the role of deep crustal magma fractionation in the production of fertile magmas essentially deny the existence of upper crustal magma chambers at the time of mineralization. To address this, we conducted a detailed thermobarometric investigation of 13 intermediate to felsic, porphyritic intrusive rocks related to porphyry-skarn Cu mineralization at Santa Rita and Hanover-Fierro, New Mexico, United States, representing two premineralization magmas (61–60 Ma), seven synmineralization magmas (60–58 Ma), and four late- to postmineralization magmas (58–57 Ma). For each sample, the pressure of last magma crystallization before final magma ascent to the current exposure level was reconstructed based on Al-in-hornblende barometry of small hornblende inclusions trapped within quartz phenocrysts and through titanium-in-quartz (TitaniQ) thermobarometry of the host quartz phenocrysts themselves. Since quartz is one of the last crystallizing magmatic minerals, and no significant phenocryst growth could have occurred in small dikes and stocks after final magma emplacement, quartz phenocrysts and their contained hornblende inclusions record the depth of last magma crystallization before final magma ascent. When present, hornblende phenocrysts and hornblende inclusions within other major phenocrysts were also analyzed. Both quartz and hornblende barometers return consistent average pressures of 3.2 ± 0.4 kbar for the entire suite of pre- to postmineralization magmas, corresponding to depths of 11 to 14 km. The synmineralization magmas return even more consistent average pressures of 3.1 ± 0.2 kbar, corresponding to a depth of 12 ± 1 km. The volume of the mineralizing porphyry dikes and stocks at the emplacement level is far too small to have provided all the fluids and metals required to form the observed ore deposits. Therefore, the majority of the ore-forming fluids must have originated from the magmas that crystallized at 12 ± 1 km depth. The ore deposits, conversely, formed at ~5-km paleodepth. This implies that most of the mineralizing fluids traveled an average vertical distance of ~7 km from their magmatic source to the eventual site of ore precipitation. The relatively unaltered nature and low veining degree of deeper parts of mineralized porphyry dikes and stocks suggest that the fluid transport through these intrusive bodies occurred mostly at near-solidus conditions by means of fluid percolation along grain boundaries. In summary, our results suggest that (1) a large, upper crustal pluton ex","PeriodicalId":11469,"journal":{"name":"Economic Geology","volume":"198200 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145651157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Formation of an Fe-Ti Deposit Within an Open-System Magmatic Chamber: Insights from the Storgangen Deposit, Rogaland Anorthosite Province, Southwest Norway","authors":"Eduardo Mansur, Alf Andre Orvik, Nolwenn Coint, Magdalena H. Huyskens, Trond Slagstad, Henrik Schiellerup, Sarah Dare","doi":"10.5382/econgeo.5185","DOIUrl":"https://doi.org/10.5382/econgeo.5185","url":null,"abstract":"The Storgangen deposit is located in the Rogaland anorthosite province, Norway, and forms an E-W–trending, 4-km-long, and up to 60-m-thick sheetlike intrusion. We have combined field and petrographic observations, whole-rock and mineral compositional variations, and Sr isotope composition through a profile across the deposit. The predominant lithology is a medium-grained, magnetite-ilmenite–rich norite, which is massif at the base and becomes gradually more fine layered upward in the stratigraphy. Although ilmenite is the predominant oxide, there is a decrease in ilmenite proportions relative to magnetite upward in the stratigraphy, which leads to lower whole-rock Ti/Fe ratios in the sampled profile. Mineral compositional variations display a decrease of compatible elements in ilmenite and magnetite (e.g., Co, Cr, V) and in Mg# in orthopyroxene upward in the stratigraphy. These compositional trends support a progressive upward fractionation during the formation of the deposit. Based on the composition of oxides, we estimate that the orebody developed following only about 40% crystallization of the parental magma and preferential accumulation of Fe-Ti oxides at the bottom of the magmatic system due to gravitational segregation. The Storgangen deposit represents a staging chamber within the Rogaland anorthosite province that was part of a larger system. In situ Sr isotope ratios in plagioclase display a slight stratigraphic variation, with 87/86Srinitial varying from 0.70558 to 0.70602, which is greater than values from the host anorthosite in the vicinity of the deposit of 0.70540 to 0.70554. Thus, if contamination occurred, it may have taken place within a deeper staging chamber prior to emplacement. Alternatively, the Sr isotope signature may be inherited from variably contaminated parental primitive jotunites previously described in the Rogaland anorthosite province. Our results support that Fe-Ti-P deposits from the Rogaland anorthosite province likely define a compositional trend from high- to low-Ti/Fe systems, with the Storgangen deposit displaying relatively intermediate Ti/Fe ratios. Such a trend has been proposed for the Central Grenville province and may thus be a global feature of Fe-Ti-P deposits associated with massif-type anorthosites.","PeriodicalId":11469,"journal":{"name":"Economic Geology","volume":"54 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145509096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrothermal Footprint of the Salobo Profundo Cu-Au Orebody, Carajás Mineral Province, Brazil","authors":"Juliana de Araújo Carvalho, Adalene Moreira Silva, Catarina Labouré Bemfica Toledo, Fernando Martins Vieira Matos, Carlos Augusto de Medeiros Filho","doi":"10.5382/econgeo.5189","DOIUrl":"https://doi.org/10.5382/econgeo.5189","url":null,"abstract":"Located in the northern sector of the Carajás mineral province, the Salobo Cu-Au deposit is the largest copper deposit in Brazil. “Salobo Profundo” (Deep Salobo) refers to the portion of the orebody beneath the final proposed pit, where deep exploration drill holes have investigated a panel approximately 700 m deep and 1,800 m long. The alteration footprint of this portion of the deposit has been documented through the integration of petrographic, hyperspectral, and geochemical data from three boreholes, totaling approximately 3,000 m. Hydrothermal zoning is characterized by albitization (Na (I)) and silicification in the distal halo, transitioning to calcic-potassic iron zones proximal to mineralization. Intense Fe metasomatism, along with potassic iron and iron alteration is most closely associated with copper and gold mineralization. Late-stage alteration is characterized by Na-Ca (II) alteration and a later type of a more intense albitic alteration (Na (II)). Hyperspectral scanning, encompassing visible-near infrared (VNIR, 380–1,000 nm), short-wave infrared (SWIR, 1,000–2,500 nm), and long-wave infrared (LWIR, 7,700–12,300 nm) wavelength ranges, has mapped the main minerals involved in the alteration processes at a centimeter-scale resolution. Minerals such as amphiboles, biotite, garnet, chlorite, quartz, and albite were identified, with garnet abundance showing a close association with copper-rich zones. The geochemical data are consistent with the characteristics of many iron oxide copper-gold (IOCG) systems, exhibiting the classic association of Fe, Cu, ± Au, along with enrichment in Ag, Bi, Co, Cs, F, Mo, Ce, La, and U. These results indicate that hyperspectral core scanning, combined with geochemical data analysis, is an effective approach for defining alteration zonation around IOCG deposits. This method enhances the characterization and refined modeling of hydrothermal zoning, providing a powerful tool for exploring for similar deposits, not only in Carajás but also in other metallogenic provinces worldwide.","PeriodicalId":11469,"journal":{"name":"Economic Geology","volume":"31 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145509127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Generation of the Zarshuran Gold Deposit in Northwest Iran Triggered by Exhumation of the Iman Khan Metamorphic Core Complex","authors":"Hongrui Zhang, Zhiming Yang, Pinghua Liu, Shu Yang, Mehraj Aghazadeh, Zengqian Hou, Tiannan Yang, Zahra Badrzadeh","doi":"10.5382/econgeo.5192","DOIUrl":"https://doi.org/10.5382/econgeo.5192","url":null,"abstract":"Zarshuran is the largest gold deposit in the Middle East. However, the structural controls and ore-forming processes at Zarshuran remain poorly understood. This study presents new geologic mapping results, detailed descriptions of ore textures, and calcite in situ U-Pb dating and thermochronological data to propose a new genetic model addressing the knowledge gap. New field mapping results demonstrate that the Zarshuran deposit is hosted in the Iman Khan Complex, which exhibits abundant ductile fabrics, and gold mineralization is spatially associated with the Zarshuran fault separating the Neoproterozoic Iman Khan and Cambrian Chaldagh units in its footwall from the Cambrian Zarshuran unit and Oligocene-Miocene Qom Formation in its hanging wall. Ore textures include syntectonic gold-bearing pyrite veins around felsic porphyroclasts, syntectonic cata-clastic flow around lenses, syntaxial euhedral calcite, and pyrite veins filled in brittle fracture and stratabound within the Qom Formation. Muscovite-quartz schist of the Iman Khan Complex underwent peak metamorphism of greenschist facies at pressure-temperature (P-T) conditions of 0.20 to 0.44 GPa and 372° to 446°C as constrained by chemical compositions of muscovite. The 40Ar/39Ar dating of syntectonic muscovite yielded a plateau age of 20.59 ± 0.32 Ma. In situ U-Pb dating of calcite associated with gold-bearing pyrite yields 14.5 ± 2.0 Ma. Apatite (U-Th)/He ages range from 12.73 ± 0.77 to 5.55 ± 0.46 Ma. These ages, combined with HeFTy thermal modeling, suggest that the Zarshuran deposit underwent a slow cooling stage from 20.6 to 14.5 Ma, a rapid cooling stage from 14.5 to 9 Ma, and an extremely slow cooling stage at <9 Ma. We propose that the Iman Khan Complex is an incipient metamorphic core complex (MCC), and gold mineralization occurred in the ductile and brittle deformation stages (20.6–14.5 Ma) associated with exhumation of the Iman Khan MCC. Other MCCs in the Tethyan metallogenic belt may be potential gold exploration targets.","PeriodicalId":11469,"journal":{"name":"Economic Geology","volume":"183 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145509094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Paragenetic Evolution of the Robertson Deposit: Eocene Reduced Intrusion-Related Gold Deposit in the Northern Shoshone Range, Nevada","authors":"Neal E. Mankins, John L. Muntean, Matthieu Harlaux, Matthew Mann, Robert A. Creaser","doi":"10.5382/econgeo.5191","DOIUrl":"https://doi.org/10.5382/econgeo.5191","url":null,"abstract":"The Robertson deposit, formerly known as Tenabo, is an Eocene reduced intrusion-related gold deposit located 5 km north of Pipeline, a world-class 20+ Moz Carlin-type gold deposit in the northern Shoshone Range, Nevada. This study is the first in-depth examination of Robertson describing gold mineralization, hydrothermal alteration, petrology of the intrusive rocks, and geochronology of the magmatic and hydrothermal events. We present six new U/Pb zircon ages of intrusive phases, one vein-hosted molybdenite Re/Os age, and one hydrothermal orthoclase 40Ar/39Ar age. Gold mineralization is spatially and temporally related to an intrusive complex referred to as the Tenabo stock, which is composed of successive intrusive phases including an early ilmenite-bearing diorite, andesite dikes, hypabyssal dacitic porphyry dikes, composite ilmenite-bearing granodiorite, granitic porphyry dikes, and hypabyssal rhyolitic dikes. Emplacement of the Tenabo stock resulted in contact metamorphism of the host siliciclastic rocks, yielding quartz, biotite, and calc-silicate hornfels that formed an aureole up to 1 km from the stock. Through petrographic observations and geochemical analyses, distinct alteration assemblages are identified, encompassing sodic-calcic, potassic, calcic, sericitic, and chloritic alteration. Petrographic observations of veins at Robertson indicate the succession of three main stages referred to as (1) pregold, (2) syngold, and (3) postgold. The pregold stage consists of barren quartz veins, potassic alteration veins comprising biotite veinlets and quartz-K-feldspar, quartz-arsenopyrite, quartz-chalcopyrite, and quartz-molybdenite veins. The syngold stage is composed of quartz-gold ± Bi-Te-Se-Pb-Ag–bearing sulfosalt veins containing native visible gold observed as single grains in quartz and/or rimming pyrrhotite, arsenopyrite, chalcopyrite, and loellingite (FeAs2) grains. The postgold veins encompass pyrite ± quartz, quartz-calcite-polymetallic sulfide veins with Pb-Zn-Sb-Ag-Sn base metal sulfides, bull quartz veins, and calcite veins. Crosscutting relationships, along with U/Pb zircon dating of intrusive phases, Re/Os molybdenite dating, and 40Ar/39Ar orthoclase dating, indicate two distinct magmatic phases at Robertson. Phase one is an early phase associated with hydrothermal activity, and phase two is a late phase associated with hypabyssal rhyolitic dikes. The period of gold mineralization at Robertson is linked with the initial phase of magmatism and subsequent hydrothermal activity, which was found to occur between 39.6 and 39.0 Ma. This study demonstrates that gold mineralization is spatially and temporally related to the emplacement of an upper Eocene 39.6 Ma reduced ilmenite-bearing intrusive complex into Paleozoic siliciclastic sedimentary rocks. This produced a high-tonnage, low-grade gold deposit characterized by an Au-As-Bi-Te-Cu metal association. Mineral assemblages observed at Robertson, comprising native bismuth, Bi sulfosal","PeriodicalId":11469,"journal":{"name":"Economic Geology","volume":"19 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145509126","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Automated Detection of Mineralization-Related Craton Structures Using Geophysical Data and Unsupervised Machine Learning","authors":"Hojat Shirmard, Ehsan Farahbakhsh, Karol Czarnota, R. Dietmar Müller","doi":"10.5382/econgeo.5188","DOIUrl":"https://doi.org/10.5382/econgeo.5188","url":null,"abstract":"Internal structures and discontinuities within cratons are economically significant due to their history of tectonic reactivation from varying intraplate stress fields, which open pathways for fluid flow and facilitate mineral deposition. However, the complex overprinting tectonic processes that make cratons prospective can also lead to uncertainty regarding their internal geometries. To address this, we take a fresh perspective on these systems by using a data-driven approach to better delineate their structures and mineral potential, focusing on the Gawler craton in South Australia. We generate over 400 magnetic and gravity anomaly features and use them as input for clustering algorithms to map clusters that represent crustal structures. We compare the efficiency of two clustering methods—self-organizing map and K-means—in outlining internal craton structures at shallow (<5 km) and deep (5–30 km) crustal depths. The results are evaluated using three performance metrics alongside geologic maps. We focus on all metallic mineral systems, including mafic-ultramafic intrusions, for Co, Cr, and Ni and intrusion-related and sediment-hosted systems for Au, Cu, Fe, and Mn. Our findings indicate that most metallic mineral occurrences, particularly significant deposits, form along the boundaries of these clusters. Approximately 80% of mineral occurrences are within 7 km of deep craton structures, and almost all follow shallow and deep structures occupying less than one-third of the study area. Our approach can be easily applied to any craton at any scale and supplemented with other geophysical data, such as magnetotelluric and regional seismic tomography data, to generate more comprehensive and reliable results.","PeriodicalId":11469,"journal":{"name":"Economic Geology","volume":"28 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145383550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New Recognition of Thallium Enrichment in the Zhangmajing Deposit, Northeast China, with Implications for the Genesis of Volcanic-Related U-Mo-Tl Mineralization","authors":"Long Zhang, Fangyue Wang, Taofa Zhou, Zhenyu Chen","doi":"10.5382/econgeo.5190","DOIUrl":"https://doi.org/10.5382/econgeo.5190","url":null,"abstract":"The Zhangmajing U-Mo deposit, located in the northern margin of the North China Craton, is unusual because both U (ca. 5,000 tonnes at 0.1–0.3% U) and Mo (0.11 million tonnes at 0.339% Mo) in this deposit are of economic interest, and Mo is mainly hosted in jordisite. In this study, thallium enrichment is recognized for the first time at Zhangmajing. This deposit is hosted within rhyolite porphyry and volcanic rocks of the Zhangjiakou Formation and surrounded by the Paleoproterozoic basement. Zircon U-Pb dating indicates that the volcanic-subvolcanic rocks were emplaced during the Early Cretaceous (141–139 Ma). Zircon Hf isotopic results show negative εHf(t) values of –20.6 to –10.9, with two-stage model ages of 1.9 to 2.5 Ga, suggesting that these rocks were dominantly derived from partial melt of Paleoproterozoic crustal materials. Whole-rock geochemical analyses indicate that the ores have highly anomalous Tl concentrations (avg 151 ppm), which are positively correlated with Mo concentrations. Ore minerals at Zhangmajing consist mostly of jordisite, pitchblende, pyrite, sphalerite, and galena. Jordisite has the highest Tl concentrations (3,307–9,921 ppm), whereas those in pyrite and sphalerite are below 2,000 ppm. Pyrite, jordisite, and sphalerite have δ34S values ranging from –16.5 to 0.3‰, suggesting that the sulfur was probably derived from a mixing of sources from the Paleoproterozoic basement and volcanic-subvolcanic rocks. This study suggests that the unusual element association of U, Mo, and Tl in Zhangmajing is the result of source rocks that are enriched in these elements, and that the metals were mainly sourced from the rocks during fluid-rock interaction and subsequently precipitated at moderate temperatures (~200°C).","PeriodicalId":11469,"journal":{"name":"Economic Geology","volume":"114 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145383549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}