Stages Of Mineralization Research Articles

Geochronology, geochemistry, and genesis of the Shamai tungsten deposit, Inner Mongolia, NE China

AbstractThe Shamai tungsten deposit is located in the western part of the Xing'an Mongolian orogenic belt of northeastern China and contains quartz‐vein hosted tungsten mineralization. In this paper, we present the results of zircon laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) U–Pb dating of the fine‐grained biotite monzogranite, medium‐grained biotite monzogranite, and porphyritic biotite monzogranite samples from the deposit as well as in situ zircon Hf isotopic and in situ plagioclase Pb isotopic analyses. Combining new laser Raman spectroscopic data for fluid inclusions with previously HO isotopic data yields insights into the precipitation of ore minerals. The fine‐grained biotite monzogranite, medium‐grained biotite monzogranite, and porphyritic biotite monzogranite were emplaced at 142.5 ± 1.0 Ma, 141.9 ± 1.1 Ma, and 140.2 ± 1.0 Ma, respectively. The fine‐ to medium‐grained biotite monzogranite and porphyritic biotite monzogranite samples contain zircons with εHf(t) values from 3.2 to 7.9 and from 4.2 to 7.6, respectively, yielding tDM2 model ages from 996 to 692 Ma and 923 to 708 Ma, respectively. The geochemical, zircon Hf isotopic, and in situ plagioclase Pb isotopic data indicate that the magmas were generated by the partial melting of juvenile crustal material mixed with mantle‐derived components. The laser Raman and HO isotopic data for fluid inclusions within tungsten‐bearing quartz veins indicate that the tungsten mineralization formed as a result of fluid mixing. Combining the data with the spatial and temporal distribution and tectonic setting of tungsten deposits in NE China suggests that this area records four stages of mineralization at 300–290, 250–230, 200–180, and 150–130 Ma. The Shamai deposit occurred in an intra‐continental extensional regime.

The genetic link between iron oxide-apatite and iron skarn mineralization in the Beizhan deposit, Western Tianshan, NW China: Evidence from magnetite and gangue mineral geochemistry

• We identify coexisting IOA ore and iron skarn ore in the Beizhan deposit. • IOA and iron skarn ore could form from a single magmatic-hydrothermal system. Multiple types of deposits could form from a single magmatic hydrothermal system. Thus, identification of the temporal, spatial and genetic link among different styles of deposits is crucial to understand the evolution of magmatic-hydrothermal systems and helpful in ore deposit exploration. Iron oxide-apatite (IOA) ores sometimes coexist with iron skarn ores in the same region, but whether these two iron ore styles could form from the single magmatic-hydrothermal system remains poorly understood. The Beizhan deposit is the largest-scale iron deposit (468 Mt, with an average of 41% Fe) in the Awulale Metallogenetic Belt (AMB) in Western Tianshan, and was previously considered to be submarine volcanic-hosted iron deposit or iron skarn deposit. In this study, we identify coexisting IOA ore and iron skarn ore in the orebody proximal to a dioritic-granitic intrusion in the Beizhan deposit. Combined with the geochemistry of magnetite and gangue minerals, we suggest that the IOA ores are consistent with formation from a high-temperature hydrothermal fluid sourced from a dioritic magma. In contrast, the iron skarn mineralization originated from a relatively low-temperature and more evolved hydrothermal fluid compared with the IOA ores. We propose the consecutive precipitation of an evolving magmatic-hydrothermal system during the two stages of iron mineralization at Beizhan, that resulted through compositional evolution of the fluid during magma differentiation. The coexisting two ore types identified in the Beizhan deposit provides insights into the evolution of the intermediate-felsic magmatic-hydrothermal systems and the genetic model of the similar ore type associations in the other deposits.

Important roles of odontoblast membrane phospholipids in early dentin mineralization.

The objective of this study was to first identify the timing and location of early mineralization of mouse first molar, and subsequently, to characterize the nucleation site for mineral formation in dentin from a materials science viewpoint and evaluate the effect of environmental cues (pH) affecting early dentin formation. Early dentin mineralization in mouse first molars began in the buccal central cusp on post-natal day 0 (P0), and was first hypothesized to involve collagen fibers. However, elemental mapping indicated the co-localization of phospholipids with collagen fibers in the early mineralization area. Co-localization of phosphatidylserine and annexin V, a functional protein that binds to plasma membrane phospholipids, indicated that phospholipids in the pre-dentin matrix were derived from the plasma membrane. A 3-dimensional in vitro biomimetic mineralization assay confirmed that phospholipids from the plasma membrane are critical factors initiating mineralization. Additionally, the direct measurement of the tooth germ pH, indicated it to be alkaline. The alkaline environment markedly enhanced the mineralization of cell membrane phospholipids. These results indicate that cell membrane phospholipids are nucleation sites for mineral formation, and could be important materials for bottom-up approaches aiming for rapid and more complex fabrication of dentin-like structures.

КАРИЙСКИЙ ЗОЛОТОРУДНЫЙ УЗЕЛ (ВОСТОЧНОЕ ЗАБАЙКАЛЬЕ): ГЕОХИМИЧЕСКИЕ ОСОБЕННОСТИ РУД, СВЯЗЬ МАГМАТИЗМА С ОРУДЕНЕНИЕМ

Dykes of the Amudzhikano-Sretenskiy complex (J3–K1) including hybrid porphyries are widely developed in the area of the Kara gold ore cluster. The parameters of the lanthanides distribution in them are close to those of ores of the quartz-tourmaline-pyrite association, indicating probable single sources of their formation. In hybrid porphyries, ΣTR is 52.24–123.35; in ores of the quartz-tourmaline-pyrite association ΣTR is 52.82–133.78. In hybrid porphyries, Eu/Sm is 0.18–0.65; in ores of the quartz-tourmaline-pyrite association Eu/Sm is 0.18–0.47. The degree of differentiation of magmatic chambers according to Eu/Eu* is 0.61-2.26 in dikes of hybrid porphyries; Eu/Eu* is 0.78–1.49 in ores of quartz-tourmaline-pyrite association. The represented data indicate that their magmatic chambers of dikes of hybrid porphyries and quartz-tourmaline-pyrite ores were not differentiated and, consequently, had a deep source. According to the geochemical composition, part of the Amudzhikano-Sretenskiy complex granite values corresponds to ore-bearing granites with goldmolybdenum mineralization. Ores of the actinolite-magnetite association are characterized by the highest gold contents among productive stages of gold mineralization. Close correlation relationships of Au with Zn, W, Mo were established in ores of the actinolite-magnetite association; in ores of the quartz-tourmaline-pyrite association – with Mo, Pb; in ores of the quartz-arsenopyrite association – with Pb, Mo, As, Ag.

Geology, geochemistry, and genesis of gold mineralization in the Chifumbazi deposit of the Tete Province, Irumide Belt, Mozambique

AbstractThe Chifumbazi gold deposit is located in the Chifunde District, Tete Province, northwestern Mozambique. The geology of the study area is composed of the Proterozoic Mualadzi Group comprising ultramafic metavolcanic rocks, quartzite, biotite‐schist, Macanda Mafic Metavolcanics, conglomerate, and granitoid of the Furancungo Suite. The geological characteristics and metallogenesis of gold mineralization in the Tete Province are poorly understood. This study describes the gold mineralization and associated hydrothermal alteration in the Chifumbazi deposit on the basis of petrography, whole‐rock geochemistry, mineral chemistry, fluid inclusion and sulfur isotope analyses. The mineralization in the Chifumbazi deposit includes auriferous quartz, calcite, dolomite and ankerite quartz‐chlorite, and chlorite‐pyrite veins and veinlets as well as sulfide dissemination hosted by altered meta‐granodiorite along shear zones and fracture zones. On a larger scale, the mineralized veins and veinlets occur along a discordant fracture system within a Pan‐African shear zone. The meta‐granodiorite host‐rock of the mineralization consists mainly of plagioclase, biotite, actinolite, and quartz, and alteration minerals calcite, dolomite, sericite, and chlorite. The meta‐granodiorite is enriched in LREE compared to HREE and shows negative Eu anomalies. The mineralization in the Chifumbazi deposit formed through three hypogene mineralization stages (Stages I–III) and one supergene stage (Stage IV). Stage I comprises quartz, calcite, dolomite, ankerite, pyrite, chalcopyrite, pyrrhotite and galena. Stage II comprises quartz, pyrrhotite, pyrite, chalcopyrite and native gold. Stage III comprises chlorite and pyrite; and Stage IV comprises secondary minerals goethite, bornite and covellite. Bulk chemical analysis of ores detected gold contents up to 5 ppm for a quartz vein of Stage II, where visible native gold is present in pyrite. The δ34SCDT values of pyrite and chalcopyrite of the Stages I–III range from +0.9 to +2.4 ‰. On the basis of the geological setting, mineralogy, and sulfur isotope signatures, the Chifumbazi deposit can be classified as orogenic.

Mineralogical and geological characteristics of the Nui Phao tungsten deposit and its resource in the Dai Tu area, northeastern Vietnam

Typically, granitic intrusions that document the lengthy and intricate history of the magmatic-hydrothermal system are linked to tungsten deposits. Uncertainty persists about the genetic relationship between tungsten mineralization and magmatic-hydrothermal development. The primary tungsten deposit in the Dai Tu region, known as the Nui Phao deposit, has been the subject of a petrographical and microscopic examination. Tungsten mineralization in the Dai Tu area often occurs in association with the formation of skarn and greisen bodies, and it has drawn much attention from geoscientists. Based on microscopic observations, tungsten ores can be divided into three mineralization stages, namely skarnisation, greisenization, and hydrothermal stage. To examine the geochemical features of the tungsten ores, the SEM-EDS and Microscope analytical methods were performed in this study. Research results indicate that the Nui Phao tungsten deposit was formed due to different tectonic and magmatism episodes. Accordingly, the Nui Phao tungsten deposit is relatively complicated with the multi-sources of ore components. Most of the tungsten ore was accumulated in association with the metasomatism between the Ordovician-Silurian carbonate-terrigenous sedimentary rocks of the Phu Ngu formation and the Cretaceous two-mica granite of the Pia Oac complex. The research results indicate that tungsten resources obtained at levels 122 and 333 are about 227.6 thousand tons. Moreover, the hydrothermal alteration and metasomatism in the study area are influenced by at least three metasomatic episodes, including skarnisation, greisenisation, and the late hydrothermal alteration of medium to a low temperature that is genetically related to fluorite-polymetallic mineralization.

Copper-Bearing Mineralisation in the Upper Devonian Limestones: A Case Study from the Historical Teresa Adit in the Świętokrzyskie Mountains, Poland

The studied copper ore deposit is located in Miedzianka Mountain (Świętokrzyskie Mountains, central Poland). This deposit was exploited from the 13th century to the 1950s; therefore numerous historical adits are currently present. One of these is Teresa adit (established in 1805), consisting of underground mining corridors and natural cave developed in the Upper Devonian limestones, partially transformed by mining works. Samples of copper- and rock-forming minerals in limestones collected at seven sites within the richest copper-bearing mineralisation in this adit were studied with petrographic investigation of thin sections, micro-area chemical analysis (EDS), and XRD. This study shows the presence of various minerals: (a) Cu-Fe sulphides (relics of chalcopyrite) and Cu sulphides (covellite, chalcocite), (b) Cu-Fe oxides (cuprite and hematite), (c) Ca and Cu carbonates (calcite, azurite, and malachite), (d) clay minerals (Fe-Mg illite), and (e) micro-crystalline silica (quartz). For the first time in the studied deposit, we described chalcopyrite relics in cuprite pseudomorphosis, hematite with admixture of vanadium in pinkish-creme veins in limestones, and the presence of an admixture of Fe-Mg illite and microcystaline silica within cracks of limestones. In addition, for the first time, unit cell parameters of malachite and azurite from Miedzianka Mountain were determined, indicating very low substitutions of atoms other than Cu in their structures. We suppose that the minerals studied were formed during three types of copper mineralisation processes: (a) hydrothermal (relics of chalcopyrite), (b) secondary weathering (chalcocite, covellite, cuprite, hematite), and (c) adsorptive mineralisation (azurite, malachite). The latter stage is related to residuum, which consists of a mixture of Fe-Mg illite and micro-crystalline quartz, which was formed during the dissolution of limestones in karst processes in some crevices. We proposed a model of the formation of copper carbonates in the adsorption stage of the copper-bearing mineralisation in Miedzianka Mountain deposits. Two generations of calcite veins (older—red calcite and younger—crème-pinkish calcite) were also detected. Mineralogical–petrographical studies of samples revealed a high scientific and educational value. Due to the fact that the Teresa adit is planned to be made available to geotourists, this work is worth presenting to the public either in the adit and/or in a local museum in Miedzianka village.

Hiekkapohja hydrothermal system – ore mineral, lithogeochemical and paleomagnetic evidence from the Paleoproterozoic Central Finland Granitoid Complex

The Paleoproterozoic Svecofennian Central Finland Granitoid Complex (CFGC) has been regarded as an area of low mineralisation potential. The Hiekkapohja area, 20km north-east of the town of Jyväskylä, host a concentration of variable metalliferous showings. Samples from mineralised boulders and outcrops display variable combinations of anomalously high concentrations of Cu, Mo, Zn, Pb, W, Pb, Ag, As, and Au. The area is composed mainly of peraluminous and ferroan granitoids. The dominant porphyritic Hiekkapohja granodiorite (~1.88 Ga) is cross-cut by the equigranular Soimavuori granite of similar age. The porphyritic Lehesvuori granite on the western side of the study area represents marginally older (~1.89 Ga) magmatism. The paragenetic sequence of the ore minerals shows that the Hiekkapohja area has been affected by at least two separate stages of hydrothermal activity. The first mineralisation stage was widespread, crystallising typically chalcopyrite, pyrrhotite, sphalerite, galena, arsenopyrite, magnetite and Ag-bearing minerals. After the first stage, a low temperature oxidising phase formed hematite and marcasite. The second mineralisation stage enclosed low temperature minerals, such as marcasite and native Ag and Ag-minerals, as inclusions inside chalcopyrite, pyrite, pyrrhotite, sphalerite, and arsenopyrite. The mineralised samples typically display signs of K-metasomatism and less commonly signs of propylitic alteration. During the second mineralisation stage the fluid flow was controlled by the dominant 120°–135° trending shear zones. Both the hydrothermal activity and the regional geology indicate that porphyry type ore forming processes have occurred in the Hiekkapohja area. Paleoproterozoic resetting of the remanent magnetisation is further evidence for the role of the hydrothermal system.

Geochemical Characteristics of the Mineral Assemblages from the Niukutou Pb-Zn Skarn Deposit, East Kunlun Mountains, and Their Metallogenic Implications

The Niukutou Pb-Zn deposit is typical of skarn deposits in the Qimantagh metallogenic belt (QMB) in the East Kunlun Mountains. In this study, based on detailed petrographical observations, electron microprobe analyses (EMPAs), and laser-ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) analyses, we report the major and trace element compositions of the typical skarn mineral assemblages (garnet, pyroxene, ilvaite, epidote, and chlorite) in this deposit. Three hydrothermal mineralization stages with different mineral assemblages of the prograde metamorphic phase were determined, which were distributed from the inside to the outside of the ore-forming rock mass. Grt1+Px1 (Stage 1), Grt2+Px2 (Stage 2), and Px3 (Stage 3) were distinguished in the Niukutou deposit. Furthermore, the ilvaites in the retrograde metamorphic phase can be divided into three stages, namely Ilv1, Ilv2, and Ilv3. The ore-forming fluid in Stage 1 exhibited high ∑REE, U, and Nd concentrations and δEu, δCe, and LREE/HREE values, which were likely derived from a magmatic–hydrothermal source and formed at high temperatures, high fO2 values, and mildly acidic pH conditions, and probably experienced diffusive metasomatism in a closed system with low water/rock ratios. In Stages 2 and 3, the ore-forming exhibited lower ∑REE, U, and Nd concentrations and δEu, δCe, and LREE/HREE values, with high Mn content that had likely experienced infiltrative metasomatism in an open system with high water/rock ratios. From Ilv1 to Ilv3, the δEu and U contents decreased, whereas the Mn content increased, indicating that the oxygen fugacity of mineralization was in decline. The ore-forming fluid evolution of the Niukutou deposit can be characterized as follows: from Stage 1 to Stage 3, the hydrothermal fluid migrated from the deep plutons to the shallow skarn and marble; the environment altered from the high fO2 and temperature conditions to low fO2 and temperature values, and the pH and Mn contents increased. The fluids contained considerable metal ore-forming materials that were favorable for the enrichment and precipitation of the Fe content. In the retrograde metamorphic phase, with the decrease in oxygen fugacity (from Ilv1 to Ilv3), the temperature and oxygen fugacity of the theore-forming fluid environment decreased, ultimately becoming conducive to the dissolution and precipitation of Pb and Zn elements.

Magmatism and mineralization of the Taolin Pb–Zn–Cu deposit in the Mufushan area, central Jiangnan Orogen (South China): Insightfvs from zircon U–Pb and sphalerite Rb–Sr geochronology, and H–O–S–Pb isotope geochemistry

The large Taolin Pb–Zn–Cu deposit contains 0.98 Mt Pb + Zn @ 2.35 % and 0.04 Mt Cu @ 0.1 %, and is associated with the Mufushan granitic complex in the central Jiangnan Orogen (JNO), South China. It consists of sulfides in hydrothermal veins, resulting from three successive mineralization stages (I–III). However, the geochronology of mineralization and ore-related granite, and sources of ore-forming fluids and materials are not well defined. Here we present zircon U–Pb dating for granite, Rb–Sr age of sphalerite, and H–O–S–Pb isotopes for ores that served to constrain the magmatism and mineralization at Taolin better. Zircon U–Pb laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) dating of the biotite monzogranite gave an age of 136 ± 0.8 Ma (MSWD = 1.8). Furthermore, an Rb–Sr isochron of sphalerite separates yielded an age of 135.4 ± 2.6 Ma (MSWD = 1.0). These results suggest that the intrusion of biotite monzogranite and Pb–Zn–Cu mineralization are contemporaneous with a close temporal relationship. δDH2O values of quartz samples from stage II range from –67.4 % to –62.5 % and calculated δ18OH2O values from –4.1 % to –1.8 ‰, indicating a mixing source of magmatic fluids and meteoric water for ore-forming fluids. S and Pb isotopic compositions of sphalerite and galena from stage II support the genetic relationship between the Pb–Zn–Cu mineralization and biotite monzogranite at Taolin and probably indicate a common source. However, previous high δ34S values (12.6 ‰ to 17.7 ‰) for barite from stage III suggest the involvement of high sulfur isotopes, which could be derived from gypsum layers within the Early-Middle Triassic sedimentary strata. The ore-related biotite monzogranite, with εHf(t) values ranging from –6.8 to –3.0 and two-stage Hf model ages ranging from 1625 to 1383 Ma, was probably derived from Neoproterozoic lower crust with a minor injection of the asthenospheric mantle. Geochronological and isotopic data demonstrate a magmatic-hydrothermal origin for the Taolin Pb–Zn–Cu deposit.

Mineral textures, mineral chemistry and S isotopes of sulphides from the Tianbaoshan Pb–Zn–Cu deposit in the Sichuan–Yunnan–Guizhou triangle: implications for mineralization process

AbstractThe carbonate-hosted Pb–Zn deposits in the Sichuan–Yunnan–Guizhou (SYG) triangle region are important Indosinian deposits in South China. The Tianbaoshan deposit is a typical large Pb–Zn deposit in the SYG area and occurs as pipe-like type, hosted by Sinian dolostone. It contains ∼26 Mt Zn–Pb ore (7.76–10.09 % Zn, 1.28–1.50 % Pb and 93.6 g t−1 Ag) and >0.1 Mt Cu ore (2.55 % Cu). In this study, the detailed mineral textures, mineral chemical and sulphur isotopic compositions of the various sulphides have been analysed to constrain the abnormal enrichment mechanism and mineralization relationship. Four mineralization stages have been recognized: Stage 1, minor early pyrite (Py1) with relics and infill of intergranular dolomite or quartz grains; Stage 2, Cu mineralization with coarse-grained, elliptical crystal chalcopyrite (Cp1); (3) Stage 3, Zn mineralization with dark fine-grained sphalerite (Sph1) and light coarse-grained sphalerite (Sph2); and (4) Stage 4, as represented by a quartz–calcite assemblage with galena, minor pyrite (Py2) and chalcopyrite (Cp2). The petrography of the sulphide minerals (Py1, Cp1, Sph1 and Sph2) demonstrates a mutual inclusion relationship. The nature of this relationship from core to rim and their similar sulphur isotope values (5.5–8.3 ‰) indicates a single sulphur source, suggesting that the different mineralization types are the result of different stages of a continuous hydrothermal system. Sphalerite geothermometer study suggests that sphalerite in the Tianbaoshan deposit formed in a low-temperature (<200 °C) hydrothermal system. The low concentrations of Mn and In, low In/Ge ratios and high Fe/Cd ratios in the sphalerite are consistent with those of Mississippi Valley-type (MVT) deposits, but different from those of magmatism-related deposits (e.g. epithermal, skarn and VMS deposits). The positive δ34S values for Py1 (5.1–7.9 ‰), Cp1 (5.1–7.2 ‰), Sph1 (4.7–7.4 ‰), Sph2 (3.9–8.7 ‰), Py2 (4.4–9.3 ‰) and Cp2 (5.0–6.8 ‰) indicate a sulphur source from thermochemical reduction of coeval seawater sulphate. Widely developed dissolved textures (caverns and breccias) with massive sulphide infillings and deformed host rock remnants suggest that replacement of host dolostones by ore fluids was volumetrically significant and the ore formed nearly simultaneously with the cavities. The Tianbaoshan deposit is a typical MVT deposit, which resulted from mixing of a H2S-rich fluid and a metal-rich fluid, with thermochemical sulphate reduction occurring before ore precipitation rather than during ore precipitation.

The Hydrothermal Evolution of the Alvo Açaí Cu (Au, Mo) Skarn Deposit, Carajás Province, Brazil

Abstract The Alvo Açaí Cu (Au, Mo) skarn deposit forms part of several poorly explored copper deposits in the western sector of the Carajás province in Brazil. Here, a 2.86 Ga metasyenogranitic basement and a 2.71 Ga quartzite of the Liberdade Group are crosscut by diabase and granitic pegmatite dikes in the deposit area. The sequence of hydrothermal alteration at Alvo Açaí is marked by (1) early pervasive calcic-sodic alteration (hastingsitealbite) and (2) potassic iron alteration (biotite-almandine-grunerite) overprinted by (3) silicification (quartz), (4) prograde (grossular-hedenbergite), and (5) retrograde (actinolite-biotite-epidote) skarn stages. Late pervasive chloritization along with epidote-calcite veinlets crosscut the previous alteration zones. The main stage of copper mineralization (I) is spatially and temporally related to the retrograde skarn alteration for which three chalcopyrite-bearing mineral assemblages are distinguished on the basis of textural relationships and mineral associations: (1) actinolite-chalcopyrite-pyrrhotite-pyrite-magnetite-molybdenite, (2) biotite-chalcopyrite-pyrite-magnetite, and (3) epidote-pyrite-chalcopyrite-sphalerite. Minor chalcopyrite occurs along rare latestage epidote-calcite veinlets (mineralization II). The evolution of a single hot H2O-NaCl-CaCl2–dominated magmatic fluid of moderate salinity (22.8–28.6 wt % NaCl + CaCl2 equiv) toward a cooler H2O-NaCl fluid, with likely variable amounts of FeCl2, MgCl2, and KCl of low to moderate salinity (0.1–33.2 wt % NaCl equiv). Fluid evolution as a result of progressive crystallization of the granitic pegmatite was likely the trigger for mineralization I as supported by calculated δ18OH2O values from retrograde quartz. The chalcopyrite and pyrite δ34S values (–1.5, –1.1, and –0.7‰) point to a magmatic origin for the sulfur, which was most probably leached from surrounding igneous host rocks. The evolution of the Alvo Açaí deposit encompasses the development of the first copper skarn mineralization recognized in the Carajás province.

Textures, in situ trace element and sulfur isotope of pyrite from the sediment-hosted Cu–Co deposits in the Zhongtiao Mountains, Trans-North China Orogen: Implications for ore genesis

Sediment-hosted Cu–Co deposits in the Zhongtiao Mountains are hosted by the metasedimentary rocks of the Paleoproterozoic Zhongtiao Group in the southern part of the trans-North China orogen, North China Craton. The ore genesis is still disputed with proposed genetic models including metamorphosed sedimentary exhalative (M−SEDEX), metamorphosed sediment-hosted stratiform copper (M−SSC) and metamorphogenic mineralization type. Pyrite occurs as a ubiquitous mineral throughout all ore-forming stages and is ideal for clarifying this issue via the integration of in situ (LA–ICP–MS and EPMA) elemental and LA–MC-ICP–MS sulfur isotope composition analyses. Two main types of pyrite are identified based on petrographic and SEM observations: fine- to medium-grained, variably deformed and inclusion-rich Py1 (including Py1a and Py1b subtypes) in the disseminated–veinlet mineralization stage (S1), and coarse-grained, fractured Py2 (including Py2a and Py2b subtypes) in the fracture-controlled vein-type mineralization stage (S2, main ore stage). Deformed and inclusion-rich Py1a is overgrown by inclusion-poor Py1b, and nonporous Py2a is rimed by porous Py2b. Geochemical results show that the studied pyrite samples have considerable contents of Co (mean > 1000 ppm) and Ni (mean > 100 ppm). These features could be related to both the Co and Ni-rich sedimentary environment (e.g., a volcaniclastic-rich sulfidic marine) and metamorphic enrichment. The content of Se (mean > 200 ppm) in Py2 is significantly higher than that in Py1, indicating the extensive interaction of mineralizing fluids with Se-bearing graphite schist. LA–ICP–MS mapping and textural studies indicate the presence of coupled dissolution-reprecipitation (CDR) reactions that could lead to trace metal compositions (e.g., Co, Ni, Se, Pb, Bi) in the product phases (Py1b, Py2b) that differ from those of their parent phases (Py1a, Py2a). These variations were most likely controlled by fluid temperature and precipitation of specific minerals. The grain-scale chemical zoning of Py2a revealed by elemental mapping indicates fluctuating fluid parameters (e.g., temperature, fS2, and/or parent fluid compositions). The bimodal distributions in Py1 (10–14 ‰ and 18–24 ‰) are consistent with the inheritance of sulfur from sedimentary pyrite and the input of thermochemical sulfate reduction (TSR) -related sulfur from reworked evaporite sulfates in an increasingly open system. The relatively lighter and wider variation in δ34S values (3.2–22.4 ‰, mean = 15.1 ‰) of Py2 implies that the evolution of the ore fluid in S2 was far more complicated, probably as a result of fluid–rock interactions and fluid cooling. During this process, hydrothermal rims with lighter δ34S values (8.4 ‰) grew on older metamorphic pyrite cores with relatively heavier δ34S values (17.4–18.2 ‰). Chalcopyrite displays overlapping S isotopic compositions with pyrite from different mineralization stages, suggesting that copper sulfides inherited reduced sulfur from earlier formed pyrite. Cooling and fluid–rock interactions serve as the critical controls triggering Cu precipitation from the fluid. The combined textural and compositional data of pyrite and chalcopyrite are suggestive of a syn-orogenic copper deposit model, in which all the ore-grade copper was introduced during the Zhongtiao orogeny.

Geological, fluid inclusion, and H–O–S–Pb isotopic constraints on the genesis of the Bajiazi mesothermal lode gold deposit in the Jiapigou ore cluster, northeast China

The Bajiazi gold deposit, located in the northeast of the North China Craton, is a typical representative of the Jiapigou ore cluster in northeast China. The deposit is hosted within the Neoarchean–Paleoproterozoic supracrustal rocks (greenstone belts) and metamorphosed plutonic rocks. The orebodies occur along NE-trending ductile–brittle faults as auriferous quartz veins. The mineral assemblages reveal three stages of mineralization: quartz–pyrite (early), quartz–polymetallic sulfide (main), and quartz–carbonate (late). Three types of primary fluid inclusions (FIs), namely A-type (aqueous), C-type (aqueous–carbonic), and PC-type (pure carbonic) FIs, have been distinguished in different stages of quartz. The early- and main-stage quartz grains contain C-, A-, and a few PC-type FIs, while the late-stage quartz grains contain only A-type FIs. The early-, main-, and late-stage FIs homogenized at temperatures of 288–397 °C, 183–281 °C, and 120–190 °C, corresponding to salinities of 8.8–19.5, 3.9–18.8, and 3.2–11.3 wt% NaCl eqv., respectively. The ore fluid system evolved from H2O–NaCl–CO2 to H2O–NaCl during ore formation. The gold precipitation resulted from fluid immiscibility during the main mineralization stage. The HO isotope data reveal that the ore fluids originally came from magmatic water, and mixed with meteoric water during ore formation. The δ34S values (−0.2 ‰ to 8.3 ‰) of ore-related sulfides suggest that the sulfur in the ores was originally magmatic-sourced, and mixed with the sulfur in wall rocks during fluid migration. The Pb isotope ratios (206Pb/204Pb = 15.890–16.794, 207Pb/204Pb = 15.188–15.530, and 208Pb/204Pb = 36.589–37.710) of ore-related sulfides indicate the metals in the ores originated primarily from the lower crust, with a minor mantle contribution, and most likely came from a deep magmatic system. The Late Triassic gold mineralization has a clear genetic link to a quartz syenite porphyry. Based on the geological, FI, and isotopic constraints, the Bajiazi deposit is classified as a mesothermal lode gold deposit, which formed in an extensional setting after the closure of the Paleo-Asian Ocean.

Genesis and Evolution of Hydrothermal Fluids in the Formation of the High-Grade Hishikari Gold Deposit: Carbon, Oxygen, and Sulfur Isotopic Evidence

The Hishikari low-sulfidation epithermal gold (Au) deposit in Kyushu, Japan, is world-famous for its premium ore. It has been hypothesized that magmatic contributions to the hydrothermal fluid during early stages of mineralization is possible, even if the hydrothermal fluids for many Au occurrences near the Hishikari deposit are of meteoric origin and are influenced by basement sedimentary rocks. The purpose of this study is to obtain constraints on the genesis and evolution of hydrothermal fluids in the formation of the high-grade Hishikari Au deposit by carbon and oxygen isotope ratios of calcite-bearing samples. Since the microanalysis of carbon and oxygen isotope ratios in every 12 μm of the calcite-bearing sample along the growth direction (corresponding to 10 years of the Hishikari mineralization) scatter in a particular range, the fluid evolution might not be a gradual change from a magmatic to a meteoric origin. Alternatively, a rapid turnover of two fluids might be happening locally. The average sulfur isotope ratio of hydrothermal pyrite is similar to that of the adjacent magma. However, according to the secondary ion mass spectrometry (SIMS) microanalysis, local pyrite with extremely low sulfur isotope ratios may interact with basement sedimentary rocks. Unlike other epithermal Au deposits in the vicinity, rapid local mixing of the magmatic-origin deep fluid and meteoric-origin fluid reacted with organic matter containing basement sedimentary rocks might cause gold precipitation at the Hishikari deposit.

REE mineralization age and geodynamic setting of the Huanglongpu deposit in the East Qinling orogen, China: Evidence from mineralogy, U–Pb geochronology, and in-situ Nd isotope

The Huanglongpu deposit is one of the most representative igneous carbonatite-type molybdenum-rare earth element (Mo-REE) deposits in the eastern Qinling metallogenic region. The molybdenum resources exceed 180 kt, whilst the total rare earth resources are about 37.8 kt. However, the age of REE mineralization, sources of ore-forming minerals, and tectonic setting are not well characterized. Therefore, this study carried out detailed mineralogical, geochronological, and geochemical analyses to provide new insights. Monazite, bastnäsite, parisite, and xenotime were found to be the dominant REE-bearing minerals in the Huanglongpu deposit. LA-ICP-MS U-Pb dating of the REE minerals revealed a two-stage REE mineralization: monazite formed at 219.4 Ma, whereas bastnäsite and xenotime formed at 145.9 Ma and 142.6 Ma, respectively. The carbonatites, as the main ore host, were characterized by a strong enrichment of light rare earth element (LREE) and moderately high heavy rare earth element (HREE) contents. Monazite showed different Nd isotopic compositions, with lower εNd(t) values ranging between −7.12 and −4.18, while the εNd(t) values of bastnäsite and xenotime ranged from −9.57 to −6.49 and from −11.13 to −6.28, respectively. These contrasting geochemical and isotopic signatures suggest that the Huanglongpu REE mineralization occurred over multiple magmatic-hydrothermal events and that the ore-forming material was unlikely to have stemmed from a single enriched mantle (EMI) source. The early REE mineralization stage (219.4 Ma) was closely associated with carbonatite-related Mo mineralization, both of which were products of magmatic mineralization during the crystallization of the host carbonatite emplaced in an extensional environment after the Late Triassic collision. The ore-related magmas may have originated from a hybrid source composed of EMI and partial melting of the lower crust. In contrast, due to the extensive Yanshanian magmatism which could provide massive heat, the later REE mineralization stage (145.9–142.6 Ma) in the Huanglongpu deposit was likely driven by the reactivation and recrystallization of early-formed REE minerals within the host carbonatites, hence representing a hydrothermal redistribution of the primary magmatic ore.

The Tatatila–Las Minas IOCG skarn (Veracruz, Mexico): Mineralogical, fluid inclusion and stable isotope constraints

The Miocene skarn deposits at Tatatila–Las Minas are found in central-eastern Veracruz state, east Mexico, near the Palma Sola massif. These deposits are geologically associated with the early stages of the Trans-Mexican Volcanic Belt (TMVB) intruded Mesozoic carbonate rocks of the Sierra Madre Oriental. Skarn associations are distributed in the classic evolution from prograde to retrograde mineralization stage. Prograde associations consist mainly of grossular-andradite, clinopyroxene, quartz, wollastonite, clinopyroxene, potassium feldspar, quartz, epidote, chromian muscovite, and are rich in magnetite, whereas retrograde associations are richer in hematite than magnetite, chlorite, fuchsite, hornblende and additionally contain chalcopyrite, pyrite, bornite, and native gold. The systematic study of fluid inclusions shows a broad variety of petrographic and microthermometric features. Fluid inclusion associations in early prograde minerals show evidence for boiling and effervescence, which are hereby interpreted as deep boiling in the -magmatic environment (or “first boiling”) with no evidence for supercritic fluids. Such a process would account for the generation of two distinct brines at ≤650 °C (a) up to ∼20 wt% NaCl equiv. and (b) up to ∼70 wt% NaCl. Both brines have cooled down independently until the brittle-ductile transition (∼400 °C) bypassed it and were able to interact with other fluids, and perhaps between with each other. Later on, deep isothermal mixing would have occurred between both brines and deeply evolved meteoric water (thermally equilibrated with host rocks). REE geochemistry of garnet suggests that mineralizing fluids at prograde stage evolved from near neutral pH and oxidizing conditions to mildly acidic and reducing conditions, perhaps reflecting the entrainment of shallow fluids. Both brines or their mixed products have experienced further dilution leading to the precipitation of retrograde associations. The most noticeable features in the retrograde stages, however, are conductive cooling and shallow isothermal mixing, this time between the products of the two pathways that originated as two distinct types of magmatic brines. The occurrence of magmatic fluids is corroborated by C and O isotope geochemistry, in which such source presents different types of water/rock interaction with sedimentary C and O from local limestones (δ13CVPDB between 0.9 and 3.7‰ and δ18OVPDB between −7.5 and −3.7‰), thus drawing an isotopic zonation that parallels the marble front associated with skarns (endoskarn calcite, δ13CVPDB between −8.5 and −3.5‰, and δ18OVPDB between −22.4 and −15.0‰). δ34SVCDT values from pyrite, chalcopyrite and galena in retrograde associations (between −3 and 4.2‰) also indicate a dominant magmatic source for sulfur, with a minor sedimentary/metasedimentary contribution. Low H2S concentrations enhanced magnetite deposition in prograde stages, and the progressive increase in H2S concentrations, coupled with a decrease in temperature by conductive cooling, led to sulfide and gold precipitation during retrograde stages. These deposits are hereby classified as IOCG skarn that were developed in association with the regional adakitic stage of the TMVB.

Shedding Light on the Role of Na,K-ATPase as a Phosphatase during Matrix-Vesicle-Mediated Mineralization

Matrix vesicles (MVs) contain the whole machinery necessary to initiate apatite formation in their lumen. We suspected that, in addition to tissue-nonspecific alkaline phosphatase (TNAP), Na,K,-ATPase (NKA) could be involved in supplying phopshate (Pi) in the early stages of MV-mediated mineralization. MVs were extracted from the growth plate cartilage of chicken embryos. Their average mean diameters were determined by Dynamic Light Scattering (DLS) (212 ± 19 nm) and by Atomic Force Microcopy (AFM) (180 ± 85 nm). The MVs had a specific activity for TNAP of 9.2 ± 4.6 U·mg-1 confirming that the MVs were mineralization competent. The ability to hydrolyze ATP was assayed by a colorimetric method and by 31P NMR with and without Levamisole and SBI-425 (two TNAP inhibitors), ouabain (an NKA inhibitor), and ARL-67156 (an NTPDase1, NTPDase3 and Ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (NPP1) competitive inhibitor). The mineralization profile served to monitor the formation of precipitated calcium phosphate complexes, while IR spectroscopy allowed the identification of apatite. Proteoliposomes containing NKA with either dipalmitoylphosphatidylcholine (DPPC) or a mixture of 1:1 of DPPC and dipalmitoylphosphatidylethanolamine (DPPE) served to verify if the proteoliposomes were able to initiate mineral formation. Around 69-72% of the total ATP hydrolysis by MVs was inhibited by 5 mM Levamisole, which indicated that TNAP was the main enzyme hydrolyzing ATP. The addition of 0.1 mM of ARL-67156 inhibited 8-13.7% of the total ATP hydrolysis in MVs, suggesting that NTPDase1, NTPDase3, and/or NPP1 could also participate in ATP hydrolysis. Ouabain (3 mM) inhibited 3-8% of the total ATP hydrolysis by MVs, suggesting that NKA contributed only a small percentage of the total ATP hydrolysis. MVs induced mineralization via ATP hydrolysis that was significantly inhibited by Levamisole and also by cleaving TNAP from MVs, confirming that TNAP is the main enzyme hydrolyzing this substrate, while the addition of either ARL-6715 or ouabain had a lesser effect on mineralization. DPPC:DPPE (1:1)-NKA liposome in the presence of a nucleator (PS-CPLX) was more efficient in mineralizing compared with a DPPC-NKA liposome due to a better orientation of the NKA active site. Both types of proteoliposomes were able to induce apatite formation, as evidenced by the presence of the 1040 cm-1 band. Taken together, the findings indicated that the hydrolysis of ATP was dominated by TNAP and other phosphatases present in MVs, while only 3-8% of the total hydrolysis of ATP could be attributed to NKA. It was hypothesized that the loss of Na/K asymmetry in MVs could be caused by a complete depletion of ATP inside MVs, impairing the maintenance of symmetry by NKA. Our study carried out on NKA-liposomes confirmed that NKA could contribute to mineral formation inside MVs, which might complement the known action of PHOSPHO1 in the MV lumen.

Geology and metallogenesis of the Tiegelongnan Cu–Au–Ag deposit, Duolong ore district, Tibet

The Tiegelongnan deposit is a giant deposit (>10 million tons Cu resources with an average grade of 0.53%) located in the west of the Bangong Co‐Nujiang metallogenic Belt, where typical porphyry and epithermal types of alteration and mineralization are developed. A compilation of geological features and mineralogical studies revealed that the Tiegelongnan deposit developed two stages of hydrothermal alteration. The early stage was related to porphyry emplacement, developing potassic, phyllic and propylitic alterations, telescoped by the late advanced argillic alteration in the shallow levels. Correspondingly, two stages of mineralization occurred, the early porphyry‐type mineralization being overlapped by the late high‐sulfidation epithermal mineralization. Due to differences in pH, log fO2, K+ activity and temperature of ore‐forming fluids, distinct sulfide minerals of low to extremely high sulfidation states, such as chalcopyrite, tennantite, enargite and covellite, precipitated throughout the entire hydrothermal process. The Tiegelongnan deposit is a complex porphyry metallogenetic system of ‘multiple structures’. The Early Cretaceous andesitic volcanic rocks of the Meiriqiecuo Formation exposed on the surface act as a cap for the ore body, beneath which an oxidizing‐leaching zone lies. Under the cap and the oxidizing‐leaching zone, a porphyry ore body is remoulded by high‐grade high‐sulfidation epithermal hydrothermal mineralization, which gradually transitions to continuous porphyry‐type mineralization at depth.

Sulfidation And Gold Precipitation In The Jugan Gold Deposit In Bau, Sarawak, East Malaysia: Insights From Correlation Plots And Factor Analysis

The Jugan Gold Deposit (JGD) is part of the Bau Mineral District (BMD) in Bau, Sarawak, East Malaysia. Although the mineral district is well studied, limited studies were conducted on the JGD. This paper presents the results of statistical studies using the multi-element geochemical data emphasizing the trace elements association with gold, alteration-mineralization, and the precipitation mechanism of the gold-bearing sulfide minerals. The correlation matrix displays positive correlation associations, particularly those associated with gold mineralization, i.e., arsenic, sulfur, antimony, and bismuth. Factor analysis grouped the trace elements into eight factors that reflect lithologies, mineralization, alteration, and geological processes in the JGD. Elements comprising the gold mineralization assemblage have the most significant factor (Factor 1) with the highest variance. The mineral assemblage was enriched during the alteration-mineralization process, as confirmed by the isocon plot. The barren samples (<0.01g/t) and gold-bearing samples (>0.2 g/t) plotted in a Fe vs. S diagram indicate that sulfidation is the precipitation mechanism of gold-bearing sulfide minerals. The immobility of iron and the vertical trajectory trend in the Fe vs. S diagram suggest that the possible source of Fe for gold-bearing sulfide minerals is the sedimentary host rock. Collectively, characteristics such as (1) the association of gold-bearing sulfide minerals with carbonate mineral assemblage and (2) high bismuth loadings on the main mineralization stage suggest a distinct geochemical characteristic of JGD relative to both Carlin-type deposits (CTD) and Carlin-like deposits (CLD); hence it is inferred to be a sedimentary-hosted gold deposit (SHGD). Establishing the JGD characteristics will contribute to a better understanding of the deposit and the BMD. Exploration-wise, it will assist future exploration work in delineating Au mineralization zones.