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17 pages, 22158 KiB  
Article
Ore Genesis of the Langcun Porphyry W-Mo Deposit, South China: Constraints from Fluid Inclusion and H-O-S Isotopics
by Kai Cui, Yunwei Qu, Yuling Xie, Kejun Yang and Zhaoqiang Huang
Minerals 2025, 15(2), 109; https://doi.org/10.3390/min15020109 - 23 Jan 2025
Viewed by 661
Abstract
The Langcun W-Mo deposit, located in the Zhejiang Province of South China, is a medium-sized porphyry deposit. The ore bodies mainly occur in aplite, granite porphyry, and the contact zone with hornfels of the Nanhua System. Four stages of mineralization are recognized in [...] Read more.
The Langcun W-Mo deposit, located in the Zhejiang Province of South China, is a medium-sized porphyry deposit. The ore bodies mainly occur in aplite, granite porphyry, and the contact zone with hornfels of the Nanhua System. Four stages of mineralization are recognized in the Langcun deposit, including the quartz–K-feldspar stage (stage I), quartz–sericite–molybdenite stage (stage II), quartz–chlorite–pyrite stage (stage III), and calcite stage (stage IV). Stages I and II are the main ore-forming stages for wolframite and molybdenite. The petrographic and microthermometric results show that four types of fluid inclusions exist in the Langcun W-Mo deposit, including two-phase liquid-rich fluid inclusions (type LV), three-phase CO2-rich fluid inclusions (type LC), pure CO2 fluid inclusions (type C), vapor H2O inclusions (type V), and multi-phase inclusions with daughter minerals (type LDV). In stage I, the fluid inclusion assemblage is LDV + LV + V, and the LDV and LV fluid inclusions have similar homogenization temperatures (281–387 °C), indicating a boiling fluid inclusions association. In stage II, the fluid inclusion assemblage is LC + C, indicating immiscibility between CO2 and aqueous fluids. The homogenization temperatures of type LC are in the range of 228–342 °C, and the salinities are in the range of 2.77–5.14 wt.% NaCl equiv. The fluid inclusions in stages III and IV are type LV, with homogenization temperatures in the ranges of 224–275 °C and 200–225 °C, respectively, and salinities in the ranges of 1.74 to 4.96 wt.% NaCl equiv and 1.06 to 3.39 wt.% NaCl equiv, respectively. Hydrogen and oxygen isotopic results indicate that the ore-forming fluids mainly come from magmatic water in the early stage and may have received an input of meteoric water in the late stage, which results in the decrease in the temperature and salinity of ore-forming fluid. Early W-Mo precipitation was induced by CO2 escape because of decompression, and fluid mixing resulted in Mo precipitation in the later stage. Full article
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30 pages, 7272 KiB  
Article
A Genetic Model for the Biggenden Gold-Bearing Fe Skarn Deposit, Queensland, Australia: Geology, Mineralogy, Isotope Geochemistry, and Fluid Inclusion Studies
by Mansour Edraki, Alireza K. Somarin and Paul M. Ashley
Minerals 2025, 15(1), 95; https://doi.org/10.3390/min15010095 - 20 Jan 2025
Cited by 1 | Viewed by 1619
Abstract
The Biggenden gold-bearing Fe skarn deposit in southeast Queensland, Australia, is a calcic magnetite skarn that has been mined for Fe and gold (from the upper portion of the deposit). Skarn has replaced volcanic and sedimentary rocks of the Early Permian Gympie Group, [...] Read more.
The Biggenden gold-bearing Fe skarn deposit in southeast Queensland, Australia, is a calcic magnetite skarn that has been mined for Fe and gold (from the upper portion of the deposit). Skarn has replaced volcanic and sedimentary rocks of the Early Permian Gympie Group, which formed in different tectonic settings, including island arc, back arc, and mid-ocean ridge. This group has experienced a hornblende-hornfels grade of contact metamorphism due to the intrusion of the Late Triassic Degilbo Granite. The intrusion is a mildly oxidized I-type monzogranite that has geochemical characteristics intermediate between those of granitoids typically associated with Fe-Cu-Au and Sn-W-Mo skarn deposits. The skarn mineralogy indicates that there was an evolution from prograde to various retrograde assemblages. Prograde garnet (Adr11-99Grs1-78Alm0-8Sps0-11), clinopyroxene (Di30-92Hd7-65Jo0-9), magnetite, and scapolite formed initially. Epidote and Cl-bearing amphibole (mainly ferropargasite) were the early retrograde minerals, followed by chlorite, calcite, actinolite, quartz, and sulfides. Late-stage retrograde reactions are indicated by the development of nontronite, calcite, and quartz. Gold is mainly associated with sulfide minerals in the retrograde sulfide stage. The fluids in equilibrium with the ore-stage calcites had δ13C and δ18O values that indicate deposition from magmatically derived fluids. The calculated δ18O values of the fluids in equilibrium with the skarn magnetite also suggest a magmatic origin. However, the fluids in equilibrium with epidote were a mixture of magmatic and meteoric water, and the fluids that deposited chlorite were at least partly meteoric. δD values for the retrograde amphibole and epidote fall within the common range for magmatic water. Late-stage chlorite was deposited from metasomatic fluids depleted in deuterium (D), implying a meteoric water origin. Sulfur isotopic compositions of the Biggenden sulfides are similar to other skarn deposits worldwide and indicate that sulfur was most probably derived from a magmatic source. Based on the strontium (87Sr/86Sr) and lead (206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb) isotope ratios, the volcanic and sedimentary rocks of the Gympie Group may have contributed part of the metals to the hydrothermal fluids. Lead isotope data are also consistent with a close age relationship between the mineralization at Biggenden and the crystallization of the Degilbo Granite. Microthermometric analysis indicates that there is an overall decrease in fluid temperature and salinity from the prograde skarn to retrograde alterations. Fluid inclusions in prograde skarn calcite and garnet yield homogenization temperatures of 500 to 600 °C and have salinities up to 45 equivalent wt % NaCl. Fluid inclusions in quartz and calcite from the retrograde sulfide-stage homogenized between 280 and 360 °C and have lower salinities (5–15 equivalent wt % NaCl). In a favored genetic model, hydrothermal fluids originated from the Degilbo Granite at depth and migrated through the shear zone, intrusive contact, and permeable Gympie Group rocks and leached extra Fe and Ca and deposited magnetite upon reaction with the adjacent marble and basalt. Full article
(This article belongs to the Special Issue Geochemistry and Genesis of Hydrothermal Ore Deposits)
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12 pages, 4421 KiB  
Article
The Crystal Chemistry and Structure of V-Bearing Silicocarnotite from Andradite–Gehlenite–Pseudowollastonite Paralava of the Hatrurim Complex, Israel
by Evgeny V. Galuskin, Irina O. Galuskina, Maria Książek, Joachim Kusz, Yevgeny Vapnik and Grzegorz Zieliński
Minerals 2024, 14(12), 1301; https://doi.org/10.3390/min14121301 - 23 Dec 2024
Cited by 1 | Viewed by 836
Abstract
Silicocarnotite, Ca5[(PO4)(SiO4)](PO4), was first described from slag over 140 years ago. In 2013, it was officially recognised as a mineral after being discovered in the larnite–gehlenite hornfels of the pyrometamorphic Hatrurim Complex. This paper describes [...] Read more.
Silicocarnotite, Ca5[(PO4)(SiO4)](PO4), was first described from slag over 140 years ago. In 2013, it was officially recognised as a mineral after being discovered in the larnite–gehlenite hornfels of the pyrometamorphic Hatrurim Complex. This paper describes the composition and structure of V-bearing silicocarnotite, crystals of which were found in a thin paralava vein cutting through the gehlenite hornfels. A network of thin paralava veins a few centimetres thick is widespread in the gehlenite hornfels of the Hatrurim Basin, Negev Desert, Israel. These veins, typically coarse crystalline rock and traditionally referred to as paralava, have a symmetrical structure and do not contain glass. Silicocarnotite in the paralava, whose primary rock-forming minerals are gehlenite, flamite, Ti-bearing andradite, rankinite and pseudowollastonite, was a relatively late-stage high-temperature mineral, crystallising at temperatures above 1100 °C. It formed from the reaction of a Si-rich residual melt with pre-existing fluorapatite. A single-crystal structural study of silicocarnotite (Pnma, a = 6.72970(12) Å, b = 15.5109(3) Å, c = 10.1147(2) Å) suggests that the phenomenon of Ca1 position splitting observed in this mineral is most likely related to the partial ordering of Si and P in the T2O4 tetrahedrons. Raman studies of silicocarnotite with varying vanadium content have shown that phases with V2O5 content of 3–5 wt.% exhibit additional bands at approximately 864 cm−1, corresponding to vibrations of ν1(VO4)3−. Full article
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21 pages, 6695 KiB  
Article
Diabase Intrusion-Induced Changes in Shale Pore Structure in Subei Basin: Insights from Mono- and Multifractal Analysis of N2 Adsorption
by Zuxian Hua, Xiaoping Liu, Biao Sun, Tian Liu, Qidong Liu, Hongliang Duan, Shili Liu, Yue Zheng, Wendi Peng and Wenhui Xie
Fractal Fract. 2024, 8(12), 737; https://doi.org/10.3390/fractalfract8120737 - 14 Dec 2024
Viewed by 882
Abstract
Diabase intrusion is a common geological phenomenon in lacustrine shale formations in continental basins in China, which has important effects on the physical and chemical properties of shale oil reservoirs. In this paper, we systematically analyzed the pore structure of diabase-intruded lacustrine shale [...] Read more.
Diabase intrusion is a common geological phenomenon in lacustrine shale formations in continental basins in China, which has important effects on the physical and chemical properties of shale oil reservoirs. In this paper, we systematically analyzed the pore structure of diabase-intruded lacustrine shale in the Gaoyou sag of the Subei Basin using geochemical tests, thin-section observation, argon ion polishing scanning electron microscopy (SEM), low-temperature nitrogen adsorption experiments (LTNA), and other methods combined with monofractal and multifractal theories. The results show that the intrusion metamorphic segments are a diabase zone, hornfels zone, slate zone, and normal shale zone from the intrusion center. The pores of hornfels and slate are mostly oriented and dissolution is obvious. Many microfractures and secondary minerals such as quartz and chlorite are observed. The pore volumes of diabase and hornfels are small, while those of slate and normal shale are larger. The monofractal dimensions D1 and D2 of the intrusion segment show a general trend of decreasing first and then increasing from the intrusion center to the shale zone. The multifractal parameters’ H index decreases gradually from the lower normal shale to the upper metamorphic zone hornfels, while Δα and Rd increase gradually. The total organic carbon (TOC) content of the intrusion zone has little effect on the pore structure, and the fractal characteristics fluctuate weakly, while the vitrinite reflectivity (Ro) value change has a significant impact on the monofractal characteristics of the shale pore. Pore volume also affects the pore heterogeneity; the larger the specific surface area (SSA) and total pore volume (TPV), the lower the pore heterogeneity and the higher the surface roughness and pore connectivity. The diabase intrusion caused three modification mechanisms of mechanical squeezing, the thermal effect, and chemical action on the shale surrounding rocks, resulting in different degrees of pore formation or change. The pore evolution model of the metamorphic belt with the combined action of “mechanical-thermal-chemical” is established, and the influence of diabase intrusion on the pore types and pore size distribution (PSD) of shale reservoirs is quantitatively described, providing a new perspective and method for understanding the impact of diabase intrusion on the characteristics and exploration potential of shale oil reservoirs. Full article
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10 pages, 2351 KiB  
Article
Rapid Determination of Ti in Quartz Using a Portable/Handheld Laser-Induced Breakdown Spectroscopy (LIBS) Instrumentation: A Case Study on Quartz Veinlets in Hornfels from Italy
by Diego Díaz Pace, Alfredo Caggianelli, Olga De Pascale and Giorgio S. Senesi
Minerals 2024, 14(12), 1257; https://doi.org/10.3390/min14121257 - 11 Dec 2024
Viewed by 865
Abstract
Recent advances in the use of portable/handheld laser-induced breakdown spectroscopy (LIBS) instrumentation have allowed its use directly in the field. In this study, a portable/handheld LIBS demo kit was tested to detect the titanium (Ti) content in some quartz veinlets hosted by hornfels [...] Read more.
Recent advances in the use of portable/handheld laser-induced breakdown spectroscopy (LIBS) instrumentation have allowed its use directly in the field. In this study, a portable/handheld LIBS demo kit was tested to detect the titanium (Ti) content in some quartz veinlets hosted by hornfels collected from the contact aureole of a Pliocene granite from Italy. Results of the present study demonstrate the promising potential of LIBS in the rapid detection of low and very variable Ti contents in quartz, which can be used as a preliminary test for the estimation of the temperature of quartz crystallization in the laboratory. However, to date, the limited availability of matrix-matched calibration samples, the refinement of sampling protocols, as well as the development of suitable algorithms for data processing and spectral analysis still require further investigation. Full article
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23 pages, 11044 KiB  
Article
The Mahout Structure in the Central Desert of Oman: A Possible Simple Impact Crater
by Sobhi Nasir, Nikos Economou, Khalil Al Hooti, Talal Al Hosni, Sean Spratley and Brian Spratley
Geosciences 2023, 13(12), 363; https://doi.org/10.3390/geosciences13120363 - 24 Nov 2023
Cited by 4 | Viewed by 3540
Abstract
The present work reports on the first evidence of a possible hypervelocity impact crater in the Sultanate of Oman. The impact origin of the structure is determined based on field observations, microscopic observations of shatter cones, planar fractures (PFs) and feather features (FFs) [...] Read more.
The present work reports on the first evidence of a possible hypervelocity impact crater in the Sultanate of Oman. The impact origin of the structure is determined based on field observations, microscopic observations of shatter cones, planar fractures (PFs) and feather features (FFs) in quartz, calcite, and feldspar, and melt-bearing polymict breccias with various types of melts. The structure consists of an elliptical bowl-shaped ridge 750 m long and 550 m wide, oriented roughly north-northeast to south-southwest. The elliptical shape and relief asymmetry indicate an oblique collision. The precursor target lithologies include local late Proterozoic Masirah Bay siliciclastic formations, carbonate and acidic volcanic rocks of the late Precambrian Halfayn Formation, and basement rocks. The crater rim, up to 15–20 m above ground, is composed of quartzite, jasper, agate, monomict siliceous and hematite breccia, and metamorphosed shale (hornfels). An ejecta blanket composed of target rocks covers the floor, outer rim, and the area extending to the immediate northeast and east of the structure. Quaternary aeolian sand covers most of the crater surface, including the 1 to 2 m thick melt-rich polymict breccia found in the crater center. The planar fractures (PFs) and feather features (FFS) in quartz and feldspar suggest a low shock pressure between 5 and 14 GPa. Our observations are consistent with set criterions for impact crater identification, confirming the possible impact origin of the Mahout structure. Full article
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18 pages, 4281 KiB  
Article
The Olivine Horizon of the Layered Monchegorsk Pluton (Kola Region, Russia): Additional Magma Injection Based on Integrated Geological and Geochronological Data
by Victor Chashchin and Sergey Sergeev
Geosciences 2023, 13(11), 344; https://doi.org/10.3390/geosciences13110344 - 9 Nov 2023
Cited by 2 | Viewed by 2030
Abstract
The paper presents the first SIMS SHRIMP U-Pb data for zircon from an olivine horizon within the Nyud intrusion of the ore-bearing layered Monchegorsk pluton (Monchepluton) in the Kola Region, Russia. A 100–150 m-thick olivine horizon occurs nearly horizontally between the melanocratic and [...] Read more.
The paper presents the first SIMS SHRIMP U-Pb data for zircon from an olivine horizon within the Nyud intrusion of the ore-bearing layered Monchegorsk pluton (Monchepluton) in the Kola Region, Russia. A 100–150 m-thick olivine horizon occurs nearly horizontally between the melanocratic and mesocratic norite of the Nyud intrusion, which disturbs its normal cumulus stratigraphic sequence. In addition, the pyroxene-plagioclase hornfelses are present at the upper contact with the olivine horizon. Twenty-three zircon grains were extracted from the large-volume olivine plagio-orthopyroxenite sample and clustered into two populations. The first population of magmatic zircon (n = 8) has a concordant and weighted average 207Pb/206Pb age of 2484.3 ± 5.6 Ma, which characterizes the formation time of the olivine horizon rocks. This serves as evidence of the olivine horizon that forms as a result of additional magma injection, which does not contradict the geological data. The 207Pb/206Pb age of single-grain zircon is 2414 ± 25 Ma, which indicates the time of postmagmatic transformations. The second population of zircon (n = 16) has a concordant and weighted average U-Pb age of 2700.6 ± 4.6 Ma, which indicates zircon absorption by olivine horizon magma probably from the rocks of the Archean greenstone belt. Full article
(This article belongs to the Section Geochemistry)
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28 pages, 41392 KiB  
Article
Geology, Petrology, and Mineralogy of Hornfels-like Rocks (Beerbachite) in the Early Paleozoic Olkhon Collisional Orogen (West Baikal Area, Russia)
by Eugene V. Sklyarov, Sergei A. Kargopolov, Andrey V. Lavrenchuk, Evgenii V. Pushkarev and Dina V. Semenova
Minerals 2023, 13(11), 1370; https://doi.org/10.3390/min13111370 - 26 Oct 2023
Cited by 1 | Viewed by 2002
Abstract
Geological, mineralogical, and petrological observations are reported for hornfels-like fine-grained granular mafic rocks in the Early Paleozoic Olkhon collisional orogen (West Baikal area, Russia). The rocks are composed of orthopyroxene, clinopyroxene, amphibole, plagioclase, and ilmenite; some samples also contain olivine, phlogopite, spinel, and [...] Read more.
Geological, mineralogical, and petrological observations are reported for hornfels-like fine-grained granular mafic rocks in the Early Paleozoic Olkhon collisional orogen (West Baikal area, Russia). The rocks are composed of orthopyroxene, clinopyroxene, amphibole, plagioclase, and ilmenite; some samples also contain olivine, phlogopite, spinel, and titanomagnetite (Opx+Cpx+Amp+Pl+Ilm±Ol±Bt±Spl±Ti-Mag). There are three occurrences of these rocks in the area: a 500 m × 1000 m field in the Shirokaya Valley, another occurrence within the Tazheran Massif (a complex of igneous and metamorphic rocks), and dismembered dikes on the southern margin of the Birkhin gabbro intrusion. The Shirokaya field is located between two 500 Ma intrusions of the Birkhin gabbro; the Tazheran occurrence coexists with syenite, including nepheline syenite, subalkaline gabbro, and marble protrusions; and the dismembered dikes coexist with carbonates and display progressive alteration of dolerite through typical granular varieties. The dikes associated with granite and marble veins mark a part of a large arc-shaped shear zone that traverses the whole intrusive body produced by rotation of a rigid gabbro block during the peak of tectonic deformation at 470–460 Ma. All three occurrences of the hornfels-like rocks lack any evident source of heat that would be responsible for the thermal alteration of the igneous protolith. We hypothesize that the precursor, subvolcanic dolerite, may have undergone autometamorphism maintained by self-generated heat. Mafic magma intruded during high-rate strike–slip faulting, which caused rapid recrystallization of magmatic minerals and produced the observed metamorphic structures. Proceeding from the controversy in the formation mechanisms, with a heat source required for hornfels but lacking from the sampled occurrences of hornfels-like rocks, we suggest identifying the latter as beerbachite, though the term has mostly fallen into disuse. The reason is that the Olkhon rocks we study have a mineralogy, structure, and texture that are perfectly identical to those of beerbachites described in publications from the first half of the 20th century. Full article
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21 pages, 18602 KiB  
Article
Genesis of the Yi’nan Tongjing Gold–Copper Skarn Deposit, Luxi District, North China Craton: Evidence from Fluid Inclusions and H–O Isotopes
by Wenyan Cai, Xiao Liu, Zhaolu Zhang, Jilei Gao, Ming Lei, Qingyi Cui, Ming Ma, Yadong Li and Yingxin Song
Minerals 2023, 13(10), 1348; https://doi.org/10.3390/min13101348 - 23 Oct 2023
Cited by 3 | Viewed by 1921
Abstract
The Luxi district presents an exceptional research area for the investigation of the significant role played by magma exsolution fluids in the mineralization process of Au–Cu deposits. A particularly noteworthy occurrence within this region is the Yi’nan Tongjing Au–Cu skarn deposit, situated in [...] Read more.
The Luxi district presents an exceptional research area for the investigation of the significant role played by magma exsolution fluids in the mineralization process of Au–Cu deposits. A particularly noteworthy occurrence within this region is the Yi’nan Tongjing Au–Cu skarn deposit, situated in the central-southern part of the Luxi district. This deposit primarily occurs in the contact zone between the early Cretaceous Tongjing complex and the Proterozoic to Cambrian sequences. The ore formation process observed in this deposit can be categorized into three distinct stages: (I) thermal metamorphism, (II) prograde alteration, and (III) retrograde alteration. The retrograde alteration stage is further divided into four sub-stages: late skarn (III-1), oxide (III-2), sulfide (III-3), and late quartz-calcite (III-4). It is primarily during the III-3 sub-stage that gold mineralization occurs. Petrographic analysis has identified three types of fluid inclusions (FIs) within garnet, quartz, and calcite grains. These include liquid-rich two-phase aqueous FIs, vapor-rich two-phase aqueous FIs, and halite-bearing multi-phase FIs. The homogenization temperatures of fluid inclusions from stages II, III-3, and III-4 range between 430–457 °C, 341–406 °C, and 166–215 °C (first to third quartiles), respectively. The garnet samples from stage II exhibit hydrogen and oxygen isotope compositions (δ18OH2O = 6.8‰ and δD = −73‰) that are indicative of a typical magma source. However, the hydrogen and oxygen isotopes of sub-stages III-1, III-2, and III-3 (δ18OH2O = 7.32‰ to 9.74‰; δD = −107‰ to −81.9‰) fall below the magma water box while the hydrogen and oxygen isotope values of III-4 (δ18OH2O = −5.3‰ to −0.9‰ and δD = −103.8‰ to −67‰) tend to move towards the meteoric water line. Furthermore, the ore-forming fluid displays characteristics of a mixture between the crustal and mantle fluids. The Tongjing complex occurred along a weakened fault zone, initiating a process of thermal metamorphism upon contact with the wall rock. This thermal metamorphism resulted in the formation of diverse assemblages, including hornfels, reaction skarns, and skarnoids. Subsequently, the upward movement of ore-forming fluids triggered exsolution which led to the establishment of a high-temperature, medium-salinity NaCl–H2O system with a single phase at depths ranging from 1–3 km. This marked the formation of the prograde alteration stage. Afterward, the ore-forming fluid underwent water–rock interactions and the admixture of meteoric water at a depth of 1–2 km. These processes facilitated phase separation, commonly referred to as boiling, resulting in the transformation of the ore-forming fluid into higher salinity fluids and lower-density gases. This evolutionary transition ultimately induced the precipitation and liberation of gold and copper from the fluid. Full article
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57 pages, 12168 KiB  
Article
Genesis and Evolution of the Yolindi Cu-Fe Skarn Deposit in the Biga Peninsula (NW Turkey): Insights from Genetic Relationships with Calc-Alkaline Magmatic Activity
by Mustafa Kaya, Mustafa Kumral, Cihan Yalçın and Amr Abdelnasser
Minerals 2023, 13(10), 1304; https://doi.org/10.3390/min13101304 - 9 Oct 2023
Cited by 3 | Viewed by 2885
Abstract
The current work investigates the impact of magmatic fluids and metasomatic processes on the Yolindi Cu-Fe skarn deposit in the Biga Peninsula, Turkey. It traces the stages of skarn evolution, from prograde to retrograde alterations, and investigates findings within a broader geological, mineralogical, [...] Read more.
The current work investigates the impact of magmatic fluids and metasomatic processes on the Yolindi Cu-Fe skarn deposit in the Biga Peninsula, Turkey. It traces the stages of skarn evolution, from prograde to retrograde alterations, and investigates findings within a broader geological, mineralogical, and geochemical framework. Additionally, it assesses the evolutionary history of the Yolindi deposit in relation to calc-alkaline magmatic activity in an island-arc environment and compares its mineral compositions and genesis with other global and regional Cu-Fe skarn deposits. The Yolindi Cu-Fe skarn deposit in the Biga Peninsula was formed by the intrusion of Şaroluk quartz monzonite pluton into Upper Paleozoic Torasan Formation rocks such as phyllite, schists, hornfels, marble, and serpentinites. During skarnification, reactions between the magmatic fluids from the Şaroluk quartz monzonite pluton and the Torasan Formation produced skarn minerals associated with metals such as Fe and Cu. Initially, these reactions formed prograde skarn minerals such as augite-rich pyroxenes and andradite garnets with magnetite and pyrite. As the system cooled, these initial minerals underwent retrograde alteration, leading to the formation of minerals such as epidote, actinolite, and chlorite, as well as other copper and iron minerals including chalcopyrite, bornite, secondary magnetite, and specular hematite. Therefore, four main stages influenced the formation of the Yolindi Cu-Fe deposit: metamorphic bimetasomatic, prograde metasomatic, and retrograde metasomatic stages. Later, oxidation and weathering resulted in supergene minerals such as cerussite, malachite, and goethite, which serve as examples of the post-metamorphic stage. The mineralogical shifts, such as the andradite–grossular transition, reflect changing hydrothermal fluid compositions and characteristics due to the addition of meteoric fluids. Importantly, the formation of magnetite after garnet and clinopyroxene during the retrograde stage is evidenced by magnetite crystals within garnet. The mineral associations of the Yolindi Cu-Fe skarn deposit align with the global skarn deposits and specific Turkish skarns (e.g., Ayazmant Fe-Cu and Evciler Cu-Au skarn deposits). The Yolindi Cu-Fe skarn deposit, in association with ore-bearing solutions having magmatic origins, developed in an island-arc setting. Full article
(This article belongs to the Special Issue New Insights into Porphyry, Epithermal, and Skarn Deposits)
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22 pages, 8725 KiB  
Article
Using 1D Thermal Modeling to Evaluate Formation Models of Mafic-Ultramafic Intrusions and Associated Sulfide Cu-Ni-PGE Mineralization
by Dmitry Stepenshchikov and Nikolay Groshev
Minerals 2023, 13(8), 1046; https://doi.org/10.3390/min13081046 - 6 Aug 2023
Viewed by 1469
Abstract
In this paper, we trace the thermal history of the mafic–ultramafic intrusions of the Monchegorsk (MC), Fedorova–Pana (FPC), and Norilsk ore-bearing complexes (NC) using an upgraded version of the author’s software Gehenna 2.2. It is shown that a key role in the concentration [...] Read more.
In this paper, we trace the thermal history of the mafic–ultramafic intrusions of the Monchegorsk (MC), Fedorova–Pana (FPC), and Norilsk ore-bearing complexes (NC) using an upgraded version of the author’s software Gehenna 2.2. It is shown that a key role in the concentration of sulfides in the lower parts of the intrusions belongs to the preliminary heating of the host rocks by early magmatic influxes. In the presence of late ore-bearing magmatic phases of a relatively small volume, the pattern of sulfide distribution within such a phase can be used to estimate the time gap with the main influx. Thermal modeling shows that the Gabbro-10 massif, an additional ore-bearing phase of the Nyud-Poaz intrusion of the MC, is separated from the main influx by a time gap of no more than 100 ka, while the minimum gap between the magmatic phases of the Fedorova intrusion of the FPC is 650–700 ka. The development of a hornfels halo around mafic–ultramafic rocks makes it possible to estimate the duration of the process of continuous magma flow inside intrusions, which, as an example from the Kharaelakh intrusion of the NC shows, can reach 1000 years and more. Thermal modeling is recommended both for formulating genetic hypotheses and for testing different scenarios for the formation of sulfide Cu-Ni-PGE mineralization in mafic–ultramafic complexes. Full article
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26 pages, 13742 KiB  
Article
Geochemical Characteristics and Metallogenic Significance of the X03 Vein Tourmaline in the Jiajika Rare Metal Deposit, West Sichuan
by Yan Qin, Yang Li, Chenghui Wang, Lijun Liu, Kejun Hou and Qian Wang
Minerals 2023, 13(6), 805; https://doi.org/10.3390/min13060805 - 13 Jun 2023
Cited by 4 | Viewed by 2384
Abstract
The Jiajika rare metal deposit contains the largest area of granitic pegmatite-type rare metal deposits in China. The X03 vein is an immense rare metal deposit dominated by lithium, which was found in the deposit in recent years. The contact metamorphic belt of [...] Read more.
The Jiajika rare metal deposit contains the largest area of granitic pegmatite-type rare metal deposits in China. The X03 vein is an immense rare metal deposit dominated by lithium, which was found in the deposit in recent years. The contact metamorphic belt of tourmalinization and petrochemistry is widely developed in its wall rocks, and the altered rocks formed contain Li and other rare metal mineralization. In this paper, the tourmaline found in the different rocks of the Jiajika X03 vein is divided into four types: two-mica quartz schist (Tur-Ⅰ), tourmaline hornfels (Tur-Ⅱ), tourmaline-bearing granite pegmatite (Tur-Ⅲ) and spodumene-bearing granite pegmatite (Tur-Ⅳ); their in situ major element, trace element and boron isotope data are systematically studied. The results show that all tourmalines in the Jiajika X03 vein deposit belong to the alkali group, and are schorl–Oxy/Fluor–schorl, dravite–Hydroxy-dravite and foitite–Oxy foitite solid solutions, among which Tur-Ⅰ are dravite, Tur-Ⅱ are foitite of hydrothermal origin and Tur-Ⅲ and Tur-Ⅳ are schorl of magmatic origin. The boron isotope values show that the boron involved the formation process of tourmaline mainly originates from the Majingzi S-type granite, and the boron isotope variations in tourmaline are controlled by melt fluid and Rayleigh fractionation. Moreover, there is a clear correlation between the B isotope value of tourmaline and the Li, Mn, Zn, Mg, and V contents, showing that these contents in tourmaline are good indicators of the mineralization type of pegmatite. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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17 pages, 13120 KiB  
Article
Geology, Mineralogy, and Age of Li-Bearing Pegmatites: Case Study of Tochka Deposit (East Kazakhstan)
by Natalya A. Zimanovskaya, Tatyana A. Oitseva, Sergey V. Khromykh, Alexey V. Travin, Ainel Y. Bissatova, Irina Yu. Annikova and Saltanat S. Aitbayeva
Minerals 2022, 12(12), 1478; https://doi.org/10.3390/min12121478 - 22 Nov 2022
Cited by 6 | Viewed by 3911
Abstract
New geological, mineralogical, geochemical, and geochronological data have been obtained for Li-bearing pegmatites from the Tochka deposit located within the Karagoin–Saryozek zone in East Kazakhstan. Earlier, the exploration works in this zone were carried out to detect only Ta and Sn mineralization, but [...] Read more.
New geological, mineralogical, geochemical, and geochronological data have been obtained for Li-bearing pegmatites from the Tochka deposit located within the Karagoin–Saryozek zone in East Kazakhstan. Earlier, the exploration works in this zone were carried out to detect only Ta and Sn mineralization, but other ores (including Li) were not considered. The estimation of lithium resources in pegmatites from the area was methodologically imperfect. Previously, it was believed that the formation of rare-metal pegmatite veins was associated with Late Carboniferous Na-granites. The obtained geological observation confirms that the ore-bearing rare-metal pegmatites at the Tochka deposits cut the Late Carboniferous Na-granites and do not cut the Early Permian Kalba granites. The associations of the accessory minerals in host hornfels, Na-granites, and rare-metal pegmatites are different and the accessory minerals in pegmatites are similar to the accessory minerals in the Kalba granites. Geochemical data show that the behavior of rare elements (Ba, Th, HFSE, and REE) and the levels of accumulation of rare metals prove that pegmatites are similar to the product of the differentiation of the granitic magmas of the Kalba complex. The 40Ar/39Ar muscovite age of the Tochka pegmatites (~292 Ma) fits the age range of the Kalba granite complex. Based on the main principles of the generation of rare-metal pegmatites, the Tochka pegmatites formed during the fluid–magmatic fractionation of magma in large granitic reservoirs of the Kalba complex. The Karagoin–Saryozek zone—located between several large granite massifs of the Kalba complex where host rocks play a role as a roof—may be very promising for rare-metal pegmatite mineralization. Full article
(This article belongs to the Special Issue Genesis and Metallogeny of Non-ferrous and Precious Metal Deposits)
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24 pages, 5143 KiB  
Article
Mineralogy and Mineral Chemistry of Dioritic Dykes, Quartz Diorite Enclaves and Pyroxene of the Sungun Cu-Mo Porphyry Deposit, East Azerbaijan, Iran
by Amin Allah Kamali, Mohsen Moayyed, Benoit M. Saumur and Mohammad Fadaeian
Minerals 2022, 12(10), 1218; https://doi.org/10.3390/min12101218 - 27 Sep 2022
Cited by 2 | Viewed by 3147
Abstract
The Sungun Cu-Mo porphyry deposit forms part of the Ahar–Arasbaran Magmatic Belt (AAMB). Its host Miocene porphyry stock is quartz monzonitic in composition and is cut by intermediate dykes that post-date mineralization. These dykes contain pyroxene and enclaves of ambiguous origin. Dykes of [...] Read more.
The Sungun Cu-Mo porphyry deposit forms part of the Ahar–Arasbaran Magmatic Belt (AAMB). Its host Miocene porphyry stock is quartz monzonitic in composition and is cut by intermediate dykes that post-date mineralization. These dykes contain pyroxene and enclaves of ambiguous origin. Dykes of microdiorite are observed within quartz diorite dykes, whereas later diorite dykes contain three different kinds of enclaves (diorite, quartz diorite and hornfels) of sizes between 1 and 10 cm. Enclaves consist of plagioclase, hornblende and biotite, with accessory sphene, quartz and apatite. Chlorite compositions in microdiorite are within the chamosite range, whereas they are within the clinochlore range in diorite enclaves. Microprobe analyses of pyroxene indicate an augitic composition (Fs13.38-22.79Wo29.1-33.57En48.53-56.61), consistent with an igneous origin. Hornblende of the diorite enclaves formed at pressures ranging between 3 and 5.3 kilobars and temperatures between 714 and 731 °C. Average oxygen fugacity during rock formation is −14.75. Such high oxygen fugacities suggest that the diorite formed near the boundaries of a convergent margin. Amphibole compositions suggest that the diorite enclaves are sub-alkaline to mildly alkaline, consistent with reported whole-rock chemistry of the Sungun magmas. Pyroxenes were formed at pressures ranging between 11 and 15 kilobars (33–45 km) and temperatures between 1100 and 1400 °C. The amount of Fe3+ in clinopyroxene is also consistent with high oxygen fugacity within their environment of crystallization. Overall, these results have implications for our understanding of the origin of the Sungun Cu-Mo porphyry magmas and their mineral deposits in a lower-crustal setting. Full article
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37 pages, 122671 KiB  
Article
A Combined EPMA and LA-ICP-MS Investigation on Bi-Cu-Au Mineralization from the Kizhnica Ore Field (Vardar Zone, Kosovo)
by Sławomir Mederski, Jaroslav Pršek, Dimitrina Dimitrova and Bahri Hyseni
Minerals 2021, 11(11), 1223; https://doi.org/10.3390/min11111223 - 3 Nov 2021
Cited by 11 | Viewed by 4140
Abstract
This paper describes a newly discovered Bi-Cu±Au mineralization co-occurring with Pb-Zn-Ag hydrothermal mineralization within the Kizhnica-Hajvalia-Badovc ore field, central Kosovo, Vardar Zone. The mineralogy of two styles of Bi-Cu±Au mineralization was described using EPMA in combination with reflected and transmitted light microscopy. Hydrothermal [...] Read more.
This paper describes a newly discovered Bi-Cu±Au mineralization co-occurring with Pb-Zn-Ag hydrothermal mineralization within the Kizhnica-Hajvalia-Badovc ore field, central Kosovo, Vardar Zone. The mineralogy of two styles of Bi-Cu±Au mineralization was described using EPMA in combination with reflected and transmitted light microscopy. Hydrothermal Cu-Bi veinlets in the Kizhnica andesite quarry consist of Bi sulfosalts (bismuthinite, cosalite, aikinite, and krupkaite), pyrite, hematite, chalcopyrite, galena, sphalerite, and tetrahedrite group minerals. Disseminated Bi-Au-Cu-Te mineralization from the contact type of mineralization (hornfels) consists of Bi sulfosalts (cannizzarite, bismuthinite, galenobismutite, cosalite), associated with sulfarsenides (arsenopyrite, gersdorffite, and cobaltite), base metal sulfides (chalcopyrite, pyrite, sphalerite, pyrrhotite, and galena), native gold, native bismuth, and tetradymite. LA-ICP-MS analyses of sphalerite, chalcopyrite, and tetrahedrite indicate increased content of In and Sn in the Kizhnica Bi-Cu-Au mineralizing system, while LA-ICP-MS analyses in pyrites show the presence of many elements, e.g., Au, As, Co, Sb, Tl, Hg, Pb, Bi related to the structure of pyrite or controlled by nano-inclusions. The results suggest a connection between Bi-Cu±Au mineralization and the proximity to intrusive rocks, which may be helpful for Au exploration in Kosovo. Full article
(This article belongs to the Special Issue Magmatic-Hydrothermal Systems through Time)
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