1959–1968

Crustal Geochemical Baselines

Contemporary themes

During 1959–1968, researchers prioritized compiling and standardizing crustal geochemistry to enable cross-study comparisons and establish robust baselines. The period saw extensive elemental tables and data harmonization that supported interpretation of anomalies and guided exploration strategies, with a strong focus on pathfinders and sampling schemes. Researchers advanced the idea that a uniform geochemical framework—rooted in global crustal abundances—could anchor ore-search decisions and enable meaningful comparisons across rocks and landscapes.

• Data compilation and standardization of crustal geochemistry enabling cross-study comparisons and baseline establishment, evidenced by large elemental tables and standardized geochemical data (1959–1964)[1][2][4][7][20].
• Ore exploration motivated by geochemical signatures and anomalies, illustrated by gold distributions in rocks, Cortez district anomalies, and sulfide ore-genesis discussions guiding prospectivity[5][15][16][17].
• Abnormal and trace metal geochemistry in humans and environments as proxies for geochemical processes and exposure, linking trace metals (nickel, chromium, tin, vanadium) to exploration-relevant signatures[6][10][13][14].
• Geochemical processes and partitioning during magmatic differentiation shaping element distributions and exploration-relevant signatures, including halogen fractionation and transition-metal uptake in magmas[3][8][18][19].
• Global crustal abundance and rare-earth patterns as baselines for interpretation; standard rocks and rare-earth distributions underpinning anomaly detection and comparative geochemistry[4][7][9].

Influential works

Influential works from this era established the quantitative foundation for exploration geochemistry. A comprehensive continental crust element abundance table became the standard baseline for interpretation and cross-study comparisons. Additional breakthroughs created practical geochemistry frameworks for mineral exploration, linking magmatic differentiation to pathfinder signatures via oxide mineralogy, and defining isotope fractionation patterns in carbonate systems that refined ore-fluid models and paleoenvironment reconstructions.

• Abundance of chemical elements in the continental crust: a new table (1964)[2] introduced a comprehensive, quantitative crustal element inventory, enabling baseline geochemistry and robust anomaly interpretation for exploration.
• Geochemistry in Mineral Exploration (1963)[3] provided a practical framework for applying geochemical data to ore-search problems, introducing sampling strategies, pathfinder concepts, and anomaly interpretation that guided generations of exploration campaigns.
• The iron-titanium oxides of salic volcanic rocks and their associated ferromagnesian silicates (1966)[13] linked Ti-Fe oxide mineralogy with magmatic differentiation and ore potential, shaping oxide-based pathfinders for mineral exploration.
• Oxygen-Isotope Fractionations in Systems Containing Dolomite (1966)[12] established isotope fractionation patterns in carbonate systems, enabling paleoenvironment reconstructions and refining ore-fluid models used in exploration.

1969–1975

Integrated Multielement Geochemical Prospecting

Contemporary themes

During the period 1969-1975, geochemical exploration consolidated into a unified, multielement framework. Regional surveys, indicator-element sets, and multivariate pattern analyses were emphasized to identify ore potential through patterns rather than relying on single-element anomalies. Biogeochemical and organic geochemistry gained prominence as exploration proxies, linking soil and terrestrial signals with subsurface mineralization and hydrocarbon environments. Isotopic frameworks for ore genesis, particularly sulfur and oxygen isotopes in sulfide systems, provided diagnostic tools for interpreting hydrothermal signatures and ore-forming processes. Methodologically, permafrost terrain exploration emerged as a distinct pattern, while mantle and crustal geochemistry supplied foundational context for interpreting ore deposits.

• Integrated multi-element geochemical data analyses emerged as a unifying approach to prospectivity, employing regional surveys, indicator-element sets, and multivariate patterns to identify ore potential rather than relying on single-element anomalies, as reflected by factor analyses, regional geochemical surveys and major/minor-element datasets[1][9][10][12].
• Biogeochemical and organic geochemistry gained prominence as exploration proxies, linking soil and terrestrial biogeochemical signals with mineralization, petroleum exploration, and organic geochemistry to infer subsurface conditions[1][2][4][5].
• Isotopic frameworks for ore genesis emerged, with sulfur and oxygen isotope geochemistry in sulfide systems, along with global gold deposit studies, shaping interpretations of ore-forming processes and hydrothermal signatures[8][13][19][20].
• Permafrost terrain exploration formed a distinct methodological pattern, integrating geological and geochemical techniques to address permafrost constraints, with Kaminak Lake and Coppermine River region case studies[15][16][17].
• Mantle and crustal geochemistry provided foundational context for ore deposit exploration, combining mantle-derived geochemical models, basalts/ocean-floor geochemistry, and petrochemical studies of volcanic belts to interpret ore genesis[7][14][18].

Influential works

The period codified a shift toward integrated geochemical data interpretation, establishing robust multi-element datasets, isotopic and stratigraphic frameworks, and proxy-based targeting that informed later predictive models for ore systems. Breakthrough analytical and conceptual advances—such as refined hydrothermal zircon processing for isotopic ages, thio complex behavior of gold, and foundational geochemical syntheses of hydrothermal ore deposits—created enduring tools and paradigms for subsequent exploration campaigns.

• A low-contamination method for hydrothermal decomposition of zircon and extraction of U and Pb for isotopic age determinations (1973)[2] introduced a novel protocol to minimize contamination during zircon dissolution and extract U and Pb cleanly for U-Pb dating, dramatically improving precision and reliability of isotopic ages in geochronology.
• Thio complexes of gold and the transport of gold in hydrothermal ore solutions (1973)[11] demonstrated that gold forms stable thio complexes, explaining its mobility in hydrothermal fluids and guiding exploration models for ore deposition.
• Geochemistry of hydrothermal ore deposits (1969)[6] provided a foundational synthesis of how geochemical processes control ore formation, establishing key concepts and methods used to assess exploration targets across hydrothermal systems.
• Ionic radii for use in geochemistry (1970)[8] compiled critical ionic radii for geochemical modeling, enabling accurate activity and size-based calculations essential for phase equilibria, mineral stability, and transport modeling.
• The geochemistry of arsenic and its use as an indicator element in geochemical prospecting (1973)[7] evaluated arsenic behavior and its role as a pathfinder element, shaping early exploration strategies and influencing many arsenic-related prospecting surveys.

1976–1982

Isotopic-Immobile Geochemistry

Contemporary themes

During this period, geochemical exploration moved toward regional data compilation and standardization enabling cross-craton and greenstone belt comparisons and more consistent regional mapping. Isotopic evidence combined with trace-element constraints became central to interpreting mantle heterogeneity, crust–mantle differentiation, and magmatic evolution, while methodological advances in partitioning, fractionation, and evolving magma chambers supported quantitative interpretation and modeling of magmatic processes. Ore-genesis investigations expanded across environments from seafloor sulphides to granitic crustal rocks, linking geochemical signatures to deposit potential and tectonic setting.

• Regional geochemical data compilation and standardization emerged as a core approach, enabling comparative exploration and regional mapping across cratons and greenstone belts[1][2][4][5][16].
• Isotopic and trace-element constraints were used to infer mantle heterogeneity, crust–mantle differentiation, and magmatic evolution, integrating stable isotopes with trace geochemistry[6][12][13][15][20].
• Methodological and theoretical frameworks for interpreting magmatic processes—partitioning, element fractionation, and evolving magma chambers—drove interpretation of geochemical signatures[8][9][13][14].
• Ore-genesis emphasis and exploration potential across varied settings, from seafloor sulphides to granitic crustal rocks, reflecting applied geochemistry in deposit studies[11][17][18][19].

Influential works

The period saw foundational work establishing isotope geochemistry as a unified framework for sourcing and dating rocks, along with comprehensive stable isotope fractionation data enabling temperature corrections and interpretation of natural variations. Experimental determinations of two-liquid partition coefficients provided the quantitative basis for magmatic differentiation models and ore-forming processes. Diagnostic schemes based on immobile elements allowed discrimination of magma series and differentiation products, while broad assessments of chemical variability in common igneous rocks supplied essential baselines for classification and exploration strategies. Collectively, these breakthroughs shifted the field from descriptive inventories to predictive, process-based geology with lasting influence on subsequent research.

• Principles of isotope geology (1977)[4] introduced a comprehensive framework for isotopic systematics, fractionation factors, and interpretation of isotope data across geologic processes, enabling robust dating and source-tracking; a cornerstone that shaped future isotopic studies.
• Compilation of stable isotope fractionation factors of geochemical interest (1977)[2] provides extensive tabulations of equilibrium fractionation factors across systems, supporting temperature corrections and robust interpretation of natural isotopic variations in rocks, waters, and minerals.
• Two-liquid partition coefficients: Experimental data and geochemical implications (1976)[15] presents measured partition coefficients for trace elements between coexisting liquid and solid phases, empowering quantitative modeling of magmatic differentiation and ore-forming processes.
• Geochemical discrimination of different magma series and their differentiation products using immobile elements (1977)[1] introduces immobile element diagnostics to distinguish magma families and differentiation trends, guiding exploration targeting and petrogenetic interpretation.
• The Chemical Variability of some Common Igneous Rocks (1976)[10] documents wide chemical variability in major and trace elements across common igneous rocks, establishing baselines for classification, petrogenesis, and exploration vectoring.

1983–1989

Isotope-Guided Geochemical Exploration

Contemporary themes

During Geochemical Exploration from 1983 to 1989, researchers consolidated isotopic and multi-element geochemistry as the primary fingerprints for ore genesis and crustal processes, marrying Pb-Sr-Nd isotope systems with trace-element signatures to discriminate source regions and ore-forming events across landscapes. Platinum-group elements and noble metals emerged as targeted tracers across diverse lithologies, guiding exploration from ophiolites to layered intrusions through fractionation patterns and mineral inclusions. In addition, rigorous standardization of geochemical data and reference samples strengthened cross-study comparability, while surface sampling strategies in weathered and coastal environments expanded exploration into marine-influenced settings.

• Isotopic and multi-element geochemistry serve as core fingerprints for ore genesis and crustal processes, integrating Pb-Sr-Nd isotopes with trace-metal signatures to distinguish source regions, petrogenesis, and ore-forming events across continents[5][9][15][19].
• Platinum-group elements and noble metals emerge as targeted tracers across diverse lithologies, guiding exploration from ophiolites to layered intrusions via fractionation, mineral inclusions, and distribution patterns[5][10][11][13][18][20].
• Standardized geochemical data and reference samples underpin interpretation and cross-study comparability, enabling robust exploration databases and comparative studies of elemental concentrations and geochemical baselines[6][7][14][15].
• Geochemical exploration in weathered and marine-influenced environments highlights surface sampling, trace metals, and coastal-deposit processes as integral parts of exploration strategies across extreme terrains[4][8][16][17].

Influential works

• Principles of Geochemistry (1983)[12] introduced a cohesive framework for interpreting element distributions, partitioning, and geochemical cycles, integrating mass balance and redox controls. This theoretical backbone shaped exploration geochemistry by guiding anomaly interpretation and ore-genesis models, with lasting influence.
• A Chemical Classification of Volcanic Rocks Based on the Total Alkali-Silica Diagram (1986)[4] introduced the TAS framework, enabling rapid field-based rock typing and standardized classification of volcanic rocks by alkali and silica content, guiding exploration and tectonic/mineralization interpretations.
• A-type granites: geochemical characteristics, discrimination and petrogenesis (1987)[1] defined a distinctive high-alkali, HFSE-rich granitoid class, with clear discrimination criteria and petrogenetic implications, linking crustal differentiation to metallogenic provinces and mineral exploration potential.
• Eh-pH Diagrams for Geochemistry (1988)[5] presented Eh–pH diagrams as practical tools to predict mineral and species stability, element mobility, and hydrothermal conditions, informing ore-formation interpretation and exploration targeting.
• Stable isotope geochemistry of ore deposits (1986)[8] synthesized isotope systematics for ore-genesis studies, enabling tracing of fluids, sources, and temperatures, and shaping both contemporary and retrospective exploration strategies.

1990–2002

Integrated Geochemical Exploration Framework

Contemporary themes

The period saw the consolidation of an integrated geochemical-fluid-genesis framework that fuses hydrothermal chemistry, fluid-rock interaction, isotopic records, and inclusion signatures to interpret ore-forming histories across scales. Geochemical signatures became central to classifying epithermal, porphyry, and intrusion-related deposits and to guiding exploration through alteration, trace metals, and zoning patterns. Regional belt-scale geochemistry translated into practical playbooks for exploration in major belts, with trace metals and rare earth elements acting as tracers for fluid sources, ore-control zoning, and alteration styles.

• Integrated geochemical-fluid-genesis framework integrates hydrothermal chemistry, fluid-rock interaction, isotopic records, and inclusion signatures to interpret ore-forming histories across scales[1][4][8][13][17][19].
• Deposit-styles and exploration guidance use geochemical signatures to classify epithermal, porphyry, and intrusion-related deposits, linking alteration, trace metals, and zoning patterns to targeting strategies[11][12][14][15][17][18].
• Regional case studies show belt-scale geochemical signals reflecting tectonics and metallogeny, translating geochemistry into exploration playbooks for Yilgarn, Meguma, Wiluna, Kalgoorlie and Victorian provinces[3][4][9][18][20].
• Trace metals and rare earths as tracers reveal hydrothermal fluid sources, ore-control zoning, and alteration styles; groundwater REE patterns and Y signatures illuminate ore-related anomalies[5][7][11][14].
• Geochemical data evaluation, presentation, interpretation, and modeling underpin decision-making, emphasizing data handling standards, anomaly delineation, and integration with geology[2][4][10].

Influential works

Influential works such as Geochemistry of hydrothermal ore deposits and Using Geochemical Data: Evaluation, Presentation, Interpretation established rigorous methods for collecting, presenting, and interpreting geochemical data, enabling cross-study comparability and robust anomaly delineation. They integrated isotopic constraints with fluid-rock interaction and zoning patterns, providing practical blueprints for ore-genesis models and exploration targeting. These methodological innovations laid the groundwork for data-driven decision-making and set enduring standards for geochemical exploration that continued to influence subsequent decades.

• Using Geochemical Data: Evaluation, Presentation, Interpretation (1993)[2] established a rigorous framework for collecting, presenting, and interpreting geochemical data, enabling consistent anomaly detection and cross-study comparability in exploration.
• Geochemistry of hydrothermal ore deposits (1997)[1] synthesizes fluid-rock interaction, trace-element zoning and alteration patterns, providing a practical blueprint for identifying ore-forming paths and prioritizing exploration targets.
• The geochemical evolution of the continental crust (1995)[3] offers a comprehensive view of crustal differentiation and element behavior, shaping models of ore genesis and establishing baseline geochemical expectations for exploration.
• Stable Isotope Geochemistry (1997)[12] assembles core isotope techniques and applications, enabling provenance, timing, and fluid-source constraints that underpin isotopic fingerprinting in ore-deposit exploration.
• A Geochemical Classification for Granitic Rocks (2001)[4] proposes a practical scheme tying granitoid geochemistry to tectonic setting, improving ore-targeting strategies in granitic terrains.

2003–2009

Integrated Atlas-Based Prospectivity

Contemporary themes

In this period geochemical exploration moved toward atlas-driven, cross-scale data platforms that fuse regional basemaps with standardized datasets and urban-to-terrestrial mapping to enable consistent interpretation. Integrated ore-deposit geochemistry guided exploration across IOCG deposits, gold-rich metamorphic belts, and skarn systems, emphasizing geochemical signatures, fluid evolution, and metallogenic controls as actionable targets. Environmental geochemistry matured around acid mine drainage and baseline trace-element partitioning, linking mineralogical context with ecological risk and monitoring, while analytical advances fostered robust quantification across geological and environmental materials.

• Systematic geochemical data platforms and atlas-based exploration frameworks unite regional basemaps with standardized datasets (European Geochemical Atlas I/II) and urban to terrestrial mapping, enabling cross-scale interpretation and comparability for exploration[2][3][10][17].
• Integrated ore-deposit geochemistry informs exploration across IOCG, gold-rich metamorphic belts, and skarn systems, highlighting geochemical signatures, fluid evolution, and metallogenic controls as exploration guides[5][7][8][12][16].
• Environmental geochemistry emphasizes acid mine drainage, trace-element partitioning, and baseline environmental chemistry, linking mineralogical contexts with ecological risk and monitoring frameworks[1][4][9][18].
• Advancements in analytical geochemistry for PGE and trace elements include on-line matrix separation methods, ID-ICP-MS, and reference materials, enabling robust quantification across geological and environmental materials[13][19][20].

Influential works

GIS-based prospectivity and geochemical anomaly mapping integrated with geographic information systems revolutionized exploration by enabling quantitative multi-criteria targeting and cross-border comparability. Foundational models for iron oxide copper-gold deposits codified geochemical signatures, oxidation states, and fluid pathways, providing structured targeting that shaped subsequent IOCG exploration. Harmonized regional baselines through the Geochemical Atlas of Europe established cross-border comparability for prospectivity and environmental baseline studies, while clumped-isotope geochemistry introduced high-precision constraints on formation conditions that enriched provenance studies.

• Geochemical Anomaly and Mineral Prospectivity Mapping in GIS (2009)[12] introduced an integrated framework linking geochemical data with Geographic Information Systems to produce quantitative prospectivity maps, enabling multi-criteria anomaly detection and spatial targeting; it reshaped exploration workflows and inspired numerous GIS-based prospectivity studies.
• Iron Oxide Copper-Gold Deposits: Geology, Space-Time Distribution, and Possible Modes of Origin (2005)[8] codified IOCG deposit models, detailing oxidation states, alteration halos, fluid pathways, and tectonic controls; established geochemical signatures and exploration targeting strategies that shaped IOCG exploration for years.
• Geochemical Atlas of Europe (2005)[5] provides harmonized regional geochemical baselines across Europe, enabling cross-border comparison and geography-specific prospectivity assessment; foundational for regional geochemical mapping and environmental baseline studies, widely used in exploration planning.
• Clumped-isotope geochemistry—The study of naturally-occurring, multiply-substituted isotopologues (2007)[11] introduced clumped-isotope measurements, delivering high-precision temperature and formation condition constraints from minerals, transforming provenance studies and isotopic age dating relevant to mineral exploration.

2010–2016

Fractal Multivariate Geochemical Prospecting

Contemporary themes

Fractal and multivariate approaches became central to geochemical anomaly detection during 2010–2016, unifying signal extraction across terrains through principal components analysis, spectrum–area fractal modeling, multifractal analyses, and generalized multi-parameter index methods to separate ore-related signals from background geochemistry. Integrated regional exploration merged geology, geophysics, and geochemistry to illuminate ore genesis and guide multidisciplinary targeting across belts such as Jiaodong, Shandong, and Dexing. Geochemical data interpretation foundations and environmental constraints shaped exploration pipelines, integrating survey analysis with environmental chemistry perspectives.

• Multivariate and fractal approaches unify anomaly detection across terrains, employing PCA, spectrum–area fractal modeling, multifractal analyses, and GMPI to separate ore-related signals from background geochemistry and to enhance prospectivity in stream sediments and geochemical data streams[4][6][8][11][13][15].
• Integrated regional exploration combines geology, geophysics and geochemistry to illuminate ore genesis and strategy in belts such as Jiaodong, Shandong and Dexing, guiding multi-disciplinary targeting and regional exploration planning[2][3][7][14][17][18].
• Theoretical/geodynamic models link gold mineralisation to accretionary orogens and regional geodynamics, offering a tectono-genetic framework for ore-system distribution and exploration across complex tectonic settings[2][10][17].
• Geochemical data interpretation foundations and environmental constraints shape exploration pipelines, data interpretation practices, and contamination assessment, integrating survey analysis with environmental chemistry perspectives[1][5][19][20].
• Deposit-scale geochemical signatures and ore-forming processes are illuminated through case studies (Dayingezhuang, Dexing, Wenyu), combining multifractal analysis, geochronology and integrated ore-genesis models to reveal timing and controls on mineralization[7][8][14][18].

Influential works

Cross-period breakthroughs included practical guidelines for interpreting geochemical surveys, enabling standardized anomaly evaluation and geological integration. Isotopic systematics of uranium in terrestrial minerals clarified provenance and timing discrimination in ore-deposit studies, promoting isotopic approaches in exploration. A unified model for gold mineralisation in accretionary orogens linked tectonics to regional-scale targeting, guiding district- to belt-scale exploration strategies, complemented by apatite trace element compositions as a robust tool for mineral exploration.

• The interpretation of geochemical survey data (2010)[10] established practical guidelines for evaluating geochemical results, including data normalization, anomaly thresholds, and geological integration, standardizing how regional surveys guide ore discovery.
• 238U/235U Systematics in Terrestrial Uranium-Bearing Minerals (2012)[4] clarified uranium isotope variations in minerals, enabling provenance and timing discrimination in exploration and promoting isotopic approaches for ore-deposit studies.
• A unified model for gold mineralisation in accretionary orogens and implications for regional-scale exploration targeting methods (2012)[12] links tectonics to gold mineralization, providing a framework for district- to belt-scale targeting and comparative studies.
• Apatite Trace Element Compositions: A Robust New Tool for Mineral Exploration (2016)[8] shows how apatite chemistry records magmatic and hydrothermal histories, offering robust vectors for mineral exploration and shaping subsequent district-scale studies.

2017–2023

Computationally Integrated Geochemical Exploration

Contemporary themes

During 2017–2023, geochemical exploration increasingly relied on data-driven integration of multi-source data and machine-assisted mapping to accelerate identification of ore-bearing zones. Deep learning and related artificial intelligence approaches enhanced multi-element vectoring across diverse deposit types, including orogenic gold, porphyry copper, Carlin-type, and tungsten-tin systems, embedding ore-genesis concepts into practical targeting strategies. Regional baselines of soils, sediments, and groundwater, together with ecological risk assessments and mineral-chemistry proxies, provided robust characterization and guided cautious exploration within complex environmental and tectonic contexts.

• Data-driven and integrative geochemical exploration leveraging multi-source data and machine-assisted mapping to identify ore-bearing zones faster. Foundations include multi-sensor satellite data for geochemical exploration[6], deep learning in geochemical mapping[11], and holistic models guiding exploration strategies[10].
• Multi-element geochemical signatures unify vectoring for diverse deposit types (orogenic gold, porphyry Cu, Carlin-type, W-Sn), consolidating ore-genesis concepts into targeting strategies. Evidence from orogenic gold studies[10][1], porphyry Cu signals[8], Carlin-type contexts[14], and trace-element vectors[15][19].
• Geochemical baselines and ecological risk assessments in soils, sediments, and groundwater establish regional characterization and guide cautious exploration. Exemplars include Dongtai baseline and ecological risk[2], Liaohe River sediment risks[13], heavy-metal soils in coal regions[4], karst geochemical background[9], and groundwater chemistry[5].
• Mineral chemistry and alteration indicators (chlorite, epidote, tourmaline, magnetite, wolframite) provide practical exploration proxies for vectoring and target delineation. Case studies span Northparkes chlorite/epidote[17], resolution porphyry mineral chemistry[18], magnetite indicator minerals[19], wolframite/scheelite traces[15], and tourmaline chemistry[20].
• Holistic ore-genesis modeling and isotopic/source-region evidence integrate timing, alteration, and geochemical signals to situate exploration within tectonic context. Foundational models of orogenic gold[10], timing at Wang’ershan[3], isotopic source work in Kiruna[16], and orogenic-gold geochemistry[1], tying geochemical signals to geodynamic settings.

Influential works

Key breakthroughs included a holistic model for the origin of orogenic gold deposits that unifies structural controls, metamorphic dehydration, and fluid-flow, directing exploration toward fault-controlled pathways. Silicon isotope geochemistry established robust tracers of crustal differentiation and fluid-rock interaction, reshaping interpretations of crustal evolution and ore-forming processes. The integration of deep learning with geochemical mapping and the development of zircon-based oxybarometry provided powerful tools for spatial prediction and redox estimation, setting new standards for interpretation and exploration strategy.

• A holistic model for the origin of orogenic gold deposits and its implications for exploration[2] integrates structural controls, metamorphic dehydration, and fluid-flow into a unified framework, clarifying multiple ore-forming stages and fault-controlled pathways; it shifted exploration toward targeted structures and fluid routes for world-class gold systems.
• Silicon Isotope Geochemistry[3] establishes silicon isotopes as robust tracers of crustal differentiation and fluid–rock interaction, providing new constraints on silicate crystallization and crustal evolution; its methodological clarity and datasets catalyzed a wave of silicon-isotope studies in geochemistry and ore-forming processes.
• Deep learning and its application in geochemical mapping[4] pioneers applying deep neural networks to geochemical data, enabling improved spatial prediction, anomaly detection, and feature extraction from complex soil and rock datasets; it catalyzed AI-driven mapping and set benchmarks for future geochemical analytics.
• New Magmatic Oxybarometer Using Trace Elements in Zircon[15] reports a zircon-based oxybarometer, linking trace-element chemistry to magmatic oxidation state; this method enables robust redox estimates for plutonic systems and magma–ore relationships, guiding exploration and petrogenetic interpretation.