Petrogenesis of Fe-Ti-(P) oxide bearing layered gabbroic intrusion in the Northern Eastern Desert of Egypt: insights into parent melt composition and genesis of oxide ores

Ore genesis of the late Paleozoic Shizui Cu-polymetallic deposit in central Jilin Province, Northeast China: Constraints from geochemistry of magnetite, chalcopyrite, and pyrite

Ore genesis of the Baimashan Fe-S crypto-explosive breccia deposit in Fanchang volcanic basin, eastern China: insights into the ultra-shallow intrusive metallogenesis

Fluid evolution and ore genesis of the Amensif Zn Cu (Pb-Ag-Au) distal skarn deposit (western High Atlas, Morocco): Constraints from fluid inclusions, crush-leach analysis, REY geochemistry, and Pb isotopes

Magnetite-apatite (MtAp) ore deposits are broadly distributed within Mesoproterozoic rocks of the New Jersey Highlands (USA); however, the age and origins of the ores, and relationships to other Fe-P-(Ti) ore deposits in the Grenvillian Orogen are presently unknown. We use zircon U-Pb geochronology and isotope geochemistry to (1) constrain the timing of MtAp mineralization in the New Jersey Highlands, (2) evaluate the relationship between the MtAp ores and associated lithologies, (3) develop a magmatic model for ore genesis, and (4) place the New Jersey ores within the context of Grenville tectonics and regional mineralization. Ore-body zircon crystals exhibit complex, magmatic textures that record episodic or prolonged crystallization over an extended duration from ca. 1074 Ma to 905 Ma, suggesting that MtAp mineralization occurred during Ottawan to post-Ottawan orogenesis. Cumulate textures of MtAp ores and a close spatial and temporal association among ores, pegmatitic granitoids (ca. 1058 Ma to ca. 986 Ma regionally), and clinopyroxene syenites (most dates ca. 1097 Ma to ca. 926 Ma at one mine) suggest that MtAp mineralization and intrusive magmatism reflect co-magmatic processes. Zircon O isotope data indicate that the MtAp deposits and associated lithologies formed from crustal melts (δ18O = 7.66‰−9.24‰ for the orthogneiss-hosted deposits and δ18O = 5.40‰−6.29‰ for the amphibolite-hosted deposit). Zircon Hf isotope data are more complex. Some MtAp deposits and associated lithologies record Hf signatures consistent with a crustal melt source (εHfi = 0.6−11.1). Whereas other MtAp deposits have extremely radiogenic signatures (εHfi = 29−542) due to the high modal abundance of apatite and monazite in the ores and, consequently, high Lu/Hf ratios. MtAp mineralization in the New Jersey Highlands is broadly coeval with MtAp mineralization in the Adirondack Highlands of New York (USA), rare earth element (REE) mineralization in the Hudson Highlands of New York, and nelsonite mineralization at Lac à l’Orignal and Lac Mirepoix in Québec (Canada). Collectively, these results indicate that orogen-scale, Fe-P-(Ti) and REE mineralization processes operated during Ottawan to post-Ottawan orogenesis throughout the Grenville orogen.

The Xa Loi gold deposit, located within the Truong Son Fold Belt of central Vietnam, provides a critical case study for understanding magmatic-hydrothermal gold systems in Southeast Asia. This study integrates sulfur (δ³⁴S), oxygen-hydrogen (δ¹⁸O–δD) isotopes, microthermometry, and stepwise-crushing gas-inclusion analyses to constrain the origin, evolution, and physicochemical conditions of the ore-forming fluid. Pyrite exhibits a narrow δ³⁴S range from –0.49‰ to +2.90‰, indicating a homogeneous sulfur source derived from magmatic degassing under moderately oxidizing conditions. Quartz δ¹⁸O and fluid δD values plot entirely within global magmatic fields, demonstrating that the aqueous component of the hydrothermal system was sourced from a deep, evolved felsic-intermediate magma with no meteoric contribution. Fluid-inclusion gases define a H₂O–CO₂–N₂–CH₄ system characterized by CO₂/CH₄ > 1 and elevated N₂/Ar ratios (≈400–1100), with all data plotting within the Magmatic-Evolved Magmatic fields of the CO₂/CH₄–N₂/Ar diagram. These signatures indicate a CO₂-rich, moderately oxidized magmatic fluid that underwent limited interaction with N-bearing crustal rocks during ascent. The progressive transition from SFI to Mixing and PFI inclusion populations records increasing oxidation consistent with magmatic degassing. Collectively, the S–O–H isotope systematics and gas compositions reveal that the Xa Loi gold deposit was formed by a magmatic-dominated hybrid fluid, in which sulfur, water, CO₂, and the conditions required for Au transport were supplied directly by an evolved magma and only slightly modified by crustal interaction. This genetic model highlights the role of deep magmatic processes in the formation of gold deposits along the Truong Son Fold Belt.

The Mapeng pluton in the central Taihang Mountains hosts significant gold mineralization; however, the magmatic processes controlling its emplacement, crystallization, and potential role in ore genesis remain debated. Previous petrological and geochemical studies have identified three internal lithofacies zones and suggested magma mixing. However, it remains uncertain whether these zones formed through in situ fractional crystallization or multiple intrusive pulses, and how magmatic dynamics contributed to gold enrichment. To address these questions, we applied quantitative crystal size distribution (CSD) analysis to constrain the intrusion history and evaluate its implications for mineralization. The CSD curves of quartz in the Mapeng granite are typically concave, with characteristic lengths (CLs) ranging from 0.78 to 1.43 mm, slopes from −1.29 to −0.70, and intercepts from −2.10 to 0.95. These variations indicate strong fluctuations in crystal growth and nucleation rates, suggesting a major influence of magma mixing. For plagioclase, the CL values range from 0.56 to 2.50 mm, slopes from −4.40 to −1.33, and intercepts from −1.21 to 3.48, further supporting the idea of multistage magma injection and crystal coarsening. Regarding crystal spatial distribution and alignment, the crystal aggregation degree (R value) ranges from 0.79 to 1.14, and the alignment factor (AF value) ranges from 0.01 to 0.19. These values suggest that the crystals tend to aggregate spatially, with their alignment degree being extremely weak, which indicates rapid magma flow disturbed by mixing processes. Notably, the R value and AF value show a negative correlation (R2 > 0.6) in the central facies and a positive correlation in the transitional facies, revealing differences in crystal accumulation mechanisms among different lithofacies zones. By synthesizing the covariance of CSD parameters and texture indices, this study infers that the Mapeng pluton experienced multiple batches of magma injection during its emplacement and consolidation. These injection events accelerated crystal dissolution and regrowth, thereby promoting crystal coarsening and textural reorganization. This study provides new quantitative mineral–textural evidence.

Accurately constraining the metal sources feeding Au mineralization provinces is crucial for understanding ore genesis but remains highly challenging. One of the best examples is the world’s second largest Carlin-type gold (Au) province in the Youjiang basin of South China, where various candidates ranging from shallow crust to deep mantle end members have been proposed as the source of Au. Some important Carlin-type Au deposits in the basin, such as the Pingle and Shijia deposits, are hosted by mantle plume−derived mafic rocks largely free from the diagenetic effects experienced by sedimentary rocks, making them ideal opportunities to put the debate to rest. Mercury (Hg) and Au are cogenetic metals within the same source of the Carlin-type Au deposits. Mass-independent fractionation of Hg isotopes (MIF-Hg, reported as Δ199Hg) results in reservoir-specific Δ199Hg values. Magmatic and hydrothermal processes do not generate MIF-Hg, with Δ199Hg being directly inherited from source regions. These characteristics make MIF-Hg a reliable diagnostic tracer to address the link between Carlin-type Au mineralization and the assumed reservoirs. Here, ore-associated sulfides from the Pingle and Shijia deposits display negative Δ199Hg (−0.27‰ to −0.03‰) values, which are distinct from the near-zero Δ199Hg (−0.06‰ to +0.04‰) values of mantle plume−related mafic hosts, the positive Δ199Hg (0.0‰ to 0.40‰) values of metasomatized subcontinental lithospheric mantle−derived ultramafic rocks, and the positive Δ199Hg (0.04‰ to 0.22‰) values of sedimentary rocks. Thus, the deep mantle beneath the Youjiang basin, mantle plume, and shallow sedimentary strata did not feed Hg, and by inference Au, for Au mineralization in the Pingle and Shijia deposits. In contrast, the negative Δ199Hg values of ore-associated sulfides are consistent with the Proterozoic basement (−0.21‰ to −0.04‰), suggesting basement as the primary metal source for the Pingle and Shijia Au deposits. Integration of the reported multiple isotopic and experimental data for other Carlin-type Au deposits in the basin shows that ore-forming metals in the Precambrian basement were predominantly leached by magmatic fluids and deep crust−derived fluids. Our study agrees with previous studies showing that there is no genetic linkage between mantle plume and Carlin-type Au mineralization in the Youjiang basin.

Deciphering ore-forming conditions and ore genesis in the Devonian Xierqu iron deposit (East Tianshan, NW China): Insights from in-situ magnetite and apatite geochemistry

LA-ICP-MS analysis of sulfides from the Sinongduo Ag-Pb-Zn deposit, Tibet: Insights into element incorporation mechanisms and ore genesis

Ore genesis and fluid evolution of the Xiaobaishitou skarn W–Mo deposit in East Tianshan, NW China: Insights from the geochemistry of garnet, scheelite, and apatite

Ore genesis of the Jinchanggouliang Au deposit in the northern North China Craton: Constraints from vein quartz and fluid inclusions

Alteration characteristics and short wavelength infrared (SWIR) spectroscopy of the Huangtupo Cu-Zn VMS deposit, NW China: Implications for ore genesis and exploration

Fluid origin and ore genesis of the Sandaocha gold deposit in Jilin Province, Northeast China: Constraints from C-H-O-He-Ar isotopes and trace element compositions of pyrite and fluid inclusion

Geological characteristics and enrichment mechanisms of the Huayagou-Jinchanggou Au Deposit: Implications for ore genesis in the Baguamiao-Jiutiaogou anomaly belt

Ore genesis of the Erdaodianzi gold deposit in Jilin Province, Northeast China: Constraints from Re–Os isotopes and geochemistry of pyrite

The Laoliwan Ag-Pb-Zn deposit is situated in the southern margin of the North China Craton and represents the first large-scale Ag-Pb-Zn ore deposit discovered in the Xiaoshan District. Ag-Pb-Zn orebodies are structurally controlled by NW- and NNW-trending faults and primarily hosted within early Cretaceous granite porphyry intrusions. In this study, sulfide Rb-Sr isotope dating and C-H-O-S-Pb multiple isotope compositions were conducted to constrain the ore genesis of this deposit. The Rb-Sr isotopic data of sulfides yield a weighted mean isochron age of 132.8 ± 9.5 Ma and an initial 87Sr/86Sr ratio of 0.7115 ± 0.00016, indicating that mineralization occurred during the early Cretaceous and the ore-forming materials were derived from a crust–mantle mixed reservoir. The δ13 C (−1.3‰ to 0.7‰), δD (−96.3‰ to −86.7‰) and δ18OH2O (0.3‰ to 5.6‰) values suggest that the ore-forming fluids were mainly derived from magmatic water with a contribution of meteoric water during mineralization. The δ34S values of sulfides (+2.0‰ to +5.8‰) indicate a magmatic source. The Pb isotope data (206Pb/204Pb = 17.301–17.892, 207Pb/204Pb = 15.498–15.560, 208Pb/204Pb = 37.873–38.029) also reveal that the ore-forming materials originated from the lower crust with a small amount from the mantle source. By integrating geochronological and geochemical data, this study proposes that the Laoliwan Ag-Pb-Zn deposit is characterized as an epithermal deposit, with potential for the discovery of concealed porphyry Cu-Mo mineralization at depth. It is inferred to be related to tectonic–magmatic–fluid activities in the context of early Cretaceous lithospheric thinning along the southern margin of the North China Craton.

ABSTRACT The southeastern part of the Sandur Schist Belt, particularly the Obulapuram area, was investigated to understand the genesis and geochemical evolution of iron ores along with associated volcano-sedimentary sequences. The iron ore bodies up to 5 km long and 50 to 100 m wide are strata-bound and comprise Banded Magnetite Quartzite (BMQ), Banded Hematite Quartzite (BHQ), massive hematite, and friable hematite of Precambrian age. Major, trace, and Rare Earth Element (REE) geochemistry of BHQ suggests a mixed origin involving deep-sea pelagic sediments and hydrothermal input, while BMQ exhibits signatures predominantly of hydrothermal derivation. The massive and friable hematite ores likely formed through extensive silica leaching and hydrothermal alteration of precursor BIF units, producing hematite-martite assemblages. Despite regional metamorphism and post-depositional fluid activity, the preserved geochemical patterns, particularly the REE distributions, suggest a depositional environment in a back-arc basin, possibly near immature island arcs, with geochemical affinities to mid-ocean ridge basalts (MORB). These interpretations integrate primary depositional features with subsequent overprints to reconstruct the complex genesis of the Obulapuram iron ores.

Enhanced solubility of gold in crude oil at high temperatures: new insights into ore genesis

Ore genesis and significance of the Dinapigui high-sulfidation epithermal Au (Cu) deposit from the northeastern Luzon Island, Philippines, insights from pyrite geochemistry