Mineralium Deposita最新文献

Multiple sulfur isotopes (δ³⁴S, δ³³S, δ³⁶S) are powerful tracers of sulfur reservoirs and fluid evolution in mineral systems, especially in granulite-facies terranes where conventional geochemical indicators may be overprinted. The Yilgarn Craton is one of the most gold-rich Cratons in the world. This study applies in situ secondary ion mass spectrometry (SIMS) to analyze sulfur isotopes in sulfide minerals from a range of Archean mineral deposits in the southwest Yilgarn Craton, Western Australia—including seven metamorphosed gold deposits, and nearby intrusion-related and volcanic-hosted massive sulfide (VHMS) systems. The results reveal systematic differences in Δ³³S values across deposit types. Intrusion-related and some VHMS deposits display near-zero Δ³³S values, consistent with sulfur derived from a primitive mantle source and limited crustal input. In contrast, metamorphosed gold deposits exhibit a broader range of Δ³³S values, reflecting mixed contributions from mantle-derived fluids and Archean sedimentary sulfur, including both sulfide- and sulfate-dominated reservoirs. These findings highlight the utility of multiple sulfur isotopes for fingerprinting sulfur sources and fluid processes in high-grade metamorphic terranes. The data underscore the diversity of sulfur reservoirs accessed by different mineral systems and offer a geochemical framework for interpreting metallogenic processes in the southwest Yilgarn Craton.

This study focuses on developing an optimal machine learning classifier to predict chalcopyrite provenance using trace element composition and to provide a robust indicator mineral tool for exploration. The trace element dataset, measured by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), comprises 2562 analyses, of which 1832 are from this study and 730 are compiled from literature, from 155 representative deposits worldwide belonging to 8 major deposit types. Random Forest (RF), Artificial Neural Network (ANN), K-Nearest Neighbors (KNN), Naive Bayes (NB) and Partial Least Square-Discriminant Analysis (PLS-DA) were tested in three contexts. The RF algorithm yields the highest overall accuracies for discrimination between: 1) magmatic and hydrothermal deposits with Ni-Ga-In-Sb–Se-Ag-Zn-Pb–Sn-Bi as predictors (97.2%), 2) Ni-Cu sulfide and Reef-type PGE deposits with Te-Sn-Se-In-Bi-Zn as predictors (98.3%), and 3) different hydrothermal deposit types using Se-Zn-Sn-In-Ga-Te-Ag-Sb-Bi-Co–Ni-Pb (93%). Additionally, the three classifiers were tested with literature data not included in the training phase (blind data) to assess the robustness in prediction, yielding a mean accuracy > 75%. The RF models were applied to classify literature chalcopyrite data from glacial till and esker sediments overlying the Churchill Province, Canada. Our models suggest that 65.4% of the detrital grains belong to hydrothermal deposits, primarily with porphyry (35.3%), iron oxide copper–gold (IOCG, 36.6%) and volcanogenic massive sulfide (VMS, 22.5%) sources, whereas 34.6% have a magmatic provenance (80.9% Ni-Cu sulfide and 19.1% Reef-type PGE deposits). Our RF models provide an accurate and robust tool to fingerprint deposit types using trace element composition of chalcopyrite for mineral exploration.

The Zhaxikang Pb-Zn-Sb-Ag-Au deposit is situated in the North Himalaya Metallogenic Belt (NHMB), southern Tibet, and is unique due to its diverse metal resources. Two mineralization events (early Pb-Zn and late Sb) in Zhaxikang are controlled by the complex Cenozoic tectonic evolution in the Himalaya. The ore bodies occur as veins and are hosted primarily by shale interbedded with sandstone and limestone. Stibnite is the dominant Sb-bearing mineral in antimony mineralization. The LA-ICP-MS trace element analyses show that stibnite is characterized by high Cu, As, and Pb contents and low Co, Ni, and Te contents, and most elements occur as solid solutions. In addition, the analytical data indicate that several elemental coupled substitution mechanisms present as (Cu⁺ + Ag⁺) + (Mn²⁺ + Pb²⁺) ↔ 2Sb³⁺ + 2□ and Cu⁺ + Zn²⁺ ↔ Sb³⁺ + □. In situ S isotope analyses of stibnite (δ³⁴S = 4.2 to 6.2‰, mean = 5.7‰) indicate a dominant sedimentary rock-sourced sulfur, which suggests leaching of slate and limestone in the Ridang Formation by the ore-forming fluid. The newly obtained stibnite Pb isotopic ratios (²⁰⁶Pb/²⁰⁴Pb = 19.55 to 19.83, ²⁰⁷Pb/²⁰⁴Pb = 15.85 to 15.89, and ²⁰⁸Pb/²⁰⁴Pb = 40.38 to 40.76) indicate that the underlying Precambrian metamorphic basement and Mesozoic sedimentary rocks both supplied substantial metals for Sb mineralization. Combined with previous studies, our new isotopic results suggest that the two mineralizing events in Zhaxikang shared similar metal sources, i.e., sedimentary and basement rocks. Both mineralization events, under compressional and extensional tectonic settings, respectively, are closely linked to coeval felsic magmatic events. Finally, trace element data were investigated using PCA which allows the identification of geochemical parameters for predicting metal associations (single Sb or Sb polymetallic deposits) in a Sb ore district, supporting the potential use of stibnite trace elements as promising indicators for exploration targeting.

Apatite is a common accessory mineral observed in alteration zones or sulfide-rich mineralized bodies of Neoarchean (ca. 2.7 and 2.5 Ga) and Paleoproterozoic (ca. 1.88 Ga) iron-oxide copper-gold (IOCG) deposits from the Carajás Province. Based on in-situ LA-ICP-MS and EPMA chemical analyses, combined with cathodoluminescence imaging, we investigate morphological and compositional variations among apatite samples from six IOCG deposits recognized in the province, including the Neoarchean Sequeirinho, GT-46, Grota Funda, and Igarapé Bahia deposits, as well as the Paleoproterozoic Sossego orebody and Alvo 118 deposit. The results of this study demonstrate that apatite in these deposits exhibit complex textural domains marked by distinct trace element compositions and REE patterns. Most of the investigated apatite varieties exhibit a hydrothermal signature linked to coupled dissolution-reprecipitation processes, which were the main responsible for REE internal remobilization within grains. This remobilization led to the precipitation of secondary REE-bearing phases (e.g., monazite, allanite) as inclusions or crystal overgrowths associated with altered domains in the analyzed grains. The compositional and morphological variations found in apatite involved distinct fluid regimes and are, therefore, interpreted to reflect the history of fluid-apatite interaction at a deposit scale. Redox conditions under which apatite crystalized vary from relatively reduced (i.e., Sequeirinho, GT-46, Grota Funda, and Sossego) to more oxidized states (i.e., Alvo 118 and Igarapé Bahia). The interaction of primary apatite domains with highly oxidizing fluids possibly suggests a Paleoproterozoic hydrothermal overprint in some of the Neoarchean studied deposits (i.e., Sequeirinho, Grota Funda, and Igarapé Bahia).