Molybdenite Samples Research Articles

Hydrothermal rutile chemistry and U-Pb age fingerprinting of the formation of the giant Nurkazgan porphyry Cu-Au deposit, Central Kazakhstan

The porphyry Cu-related intrusions commonly comprise multiple phases such as the large Nurkazgan porphyry Cu-Au deposit in Central Kazakhstan, hosted in the Karagandinsky dioritic to granitic intrusive complex. Here, SHRIMP and LA-ICP-MS zircon U-Pb dating on the multiple ore-bearing intrusions from this complex confirms a punctuated magmatic history distributed over 35 m.y., and marked by three episodic porphyry events rather than a single event, with the oldest event being the early granodiorite and quartz diorite porphyries at ca. 437–440 Ma, the second being the quartz diorite porphyry at 429.7 ± 2.1 Ma, and the last being the late granodiorite and quartz diorite porphyries at 402.8 ± 3.7 Ma and 402.0 ± 3.9 Ma, respectively. The mineralization is related to the two younger episodic intrusions of quartz diorite porphyry at ∼ 430 Ma and ∼ 402 Ma, respectively. SIMS U-Pb dating of hydrothermal, Cu-rich (up to 20.9 ppm) rutile from the breccia-type ores directly constrains the timing of porphyry mineralization at 428.9 ± 6.9 Ma, which is coincident with the emplacement age of the ∼ 430 Ma quartz diorite porphyry, and thus demonstrates this porphyry as a causative intrusion generating main-stage mineralization. This close genetic link is also supported by the chondrite-normalized REE patterns of rutile, which show remarkably similar light REE-enrichments and moderate negative Eu anomalies to those of the ∼ 430 Ma quartz diorite porphyry. A molybdenite sample obtained from the main-ore stage vein, however, has a Re-Os age of 418.6 ± 1.8 Ma, which is slightly younger than the U-Pb age determinations of rutile. This indicates that the Re-Os isotope system was disturbed by the second (post-ore) thermal event related to ∼ 402 Ma quartz diorite porphyry. In line with published data, this study suggests that the rutile U-Pb age in combination with its REE patterns can be a powerful tool to trace the causative porphyry. Moreover, the typical LREE-enriched REE patterns coupled with the high Cu anomalies, inherited from the causative porphyry and related exsolving fluids, can be as diagnostic proxies for distinguishing the porphyry Cu-related hydrothermal rutile from those formed in orogenic gold deposits. Based on these two geochemical discriminators and U-Pb ages, rutile can serve as unique fingerprints to help improve porphyry copper exploration in green field or covered terranes to complement detrital zircon fertility indicators.

LA-ICP-Q-MS/MS Re[sbnd]Os geochronology: A comparison of N2O and CH4 reaction gases

The ReOs isotope system can directly date sulphide formation, making it useful for ore deposit studies. Recent work has demonstrated that laser ablation inductively coupled tandem mass spectrometry (LA-ICP-MS/MS) can be used to effectively separate 187Re from 187Os during analysis by reacting Os with CH4 gas, allowing for in situ ReOs age determination of molybdenite. However, the age calculation often requires a significant interference correction of 187ReCH2+ on 187OsCH2+. Here, we demonstrate that N2O gas is a viable alternative reaction gas for in situ ReOs geochronology. In this new method, Os forms a tetra-oxide complex, while Re shows very low reactivity with the N2O reaction gas (∼0.15 %), reducing the isobaric interference correction requirement relative to the CH4 method. We compare results from both reaction gases across a range of molybdenite samples of different ages (spanning ca. 1700–300 Ma), demonstrating that the N2O method achieves greater precision and accuracy for young molybdenite samples (ca. 300 Ma) compared to CH4. In addition, we demonstrate that in situ ReOs is capable of dating high-Re pyrite (i.e., >10 ppm).

A hydrometallurgical process flowsheet for recovering MoO3 from Molybdenite

In this study, a comprehensive hydrometallurgical processing of molybdenite (MoS2) concentrate was investigated. This investigation involved a novel approach combining mechanical activation, leaching, and polyelectrolyte extraction methods. The integrated method effectively addressed the challenge of low leaching rate of molybdenite, resulting in the successful production of high-purity molybdenum trioxide. Milled molybdenite samples were analyzed by different methods of X-ray diffraction, atomic force and electron microscopy, and BET. The increasing trend of the specific surface area during milling was determined by a model fitting which was useful for optimization of milling time. Several leaching reagents were studied to achieve high molybdenum dissolution. The most promising results were achieved through a two-hour process, yielding an impressive leaching efficiency of 80% and a resulting Mo concentration of 6700 mg/L. Molybdenum recovery was efficiently carried out through polyelectrolyte extraction, as confirmed by ICP and CHNS analyses, demonstrating selective precipitation of molybdenum from the solution. The subsequent calcination of the precipitated molybdenum(VI) compound resulted in the production of high-purity molybdenum trioxide. Furthermore, a conceptual hydrometallurgical treatment process for molybdenite concentrate was proposed, aiming to recover molybdenum, sulfuric acid, and copper. This proposed process presents a promising avenue for further exploration in pilot plant studies within the molybdenum industry.

Characterization and Timing of Mineralization in the Garrison Gold District, Southern Abitibi Greenstone Belt, Canada

Abstract The decrease in gold discoveries is affecting the deployment of new technology and the general society demand, demonstrating the need for new gold exploration approaches. To date, gold exploration remains primarily focused in areas near well-known large gold districts. We demonstrate the potential for new discoveries and significant resource expansion in the Abitibi greenstone belt distal from the giant gold districts across the belt. Unlocking of additional resources in the Garrison district was accomplished by identification of zones of compentency contrast, which resulted in a variety of locally complex and unrecognized structural traps receptive to gold. Our approach is applicable to other little-explored areas in the Abitibi greenstone belt and other orogenic belts worldwide. The Garrison district, situated in the southern part of the Abitibi greenstone belt in the Superior province, lies along an ~3-km NE-trending segment of the gold-rich, Archean Porcupine-Destor deformation zone. The district contains several discoveries, which include the Buffonta deposit hosted in mafic volcanic rocks, the syenite-hosted 903 deposit, and the albitite dike-hosted Jonpol deposit. These deposits occur along high-strain zones developed in embayments and elongate, NE-trending domains of talc-chlorite-serpentine–altered ultramafic rocks, which localized strands and splays of the Porcupine-Destor deformation zone. In addition, the Garrcon deposit comprises northerly-trending gold-bearing quartz veins and lamprophyre dike swarms hosted in sedimentary host rocks that are bounded by high-strain zones. The intrusive rocks in all of these deposits were emplaced prior to gold deposition. They provided a competent substrate in areas of heterogeneous strain that localized gold mineralization. Initial alteration made the surrounding volcanic and sedimentary rocks also rheologically competent. This resulted in enhanced hydrofracturing and the formation of paragenetically late gold-bearing quartz veins. Widespread albite-pyrite-carbonate alteration in all of the gold deposits temporally overlapped with gold mineralization. New U-Pb zircon geochronology data reveal that ~2719 to 2712 Ma volcanism was followed by granitic magmatism and emplacement of a series of ~2683 to 2672 Ma dikes. One Re-Os analysis of a synmineralization molybdenite sample indicates that orogenic gold was deposited at 2671 ± 12 Ma. This is comparable to published ages of major orogenic gold deposits throughout the southern part of the Abitibi greenstone belt, indicating a broadly synchronous principal gold event across the belt.

Origin and evolution of a porphyry-skarn-stratabound system: constraints from geology, magmatic-hydrothermal zircon U–Pb and molybdenite Re–Os geochronology, and in situ S isotopes of the Dongguashan Cu(–Au) deposit, eastern China

Intrusion-related stratabound deposits within Late Carboniferous carbonate units are an abundant and highly economically significant ore type in eastern China. In such deposits, stratabound mineralization commonly coexists with porphyry and/or skarn mineralization, and the vast majority of reserves (>90 %) are derived from extensive stratabound orebodies, which are easy to exploit and of great interest to geologists. However, it is unclear whether these deposits were formed via the Late Carboniferous seafloor sedimentary exhalation formation or the Early Cretaceous magmatic-hydrothermal processes. Moreover, the fluid and sulfur isotope variations within porphyry-skarn-stratabound systems have not been adequately constrained. We investigated the Dongguashan deposit, one of the largest and most representative stratabound Cu(–Au) deposits in eastern China. Three mineralization types were recognized based on field and petrologic studies: porphyry, skarn, and stratabound. In the stratabound mineralization zone, magmatic and hydrothermal zircons from laminated ores yielded concordant U–Pb ages of 137.3 ± 1.1 and 135.7 ± 1.4 Ma, respectively, while molybdenite samples from vein-like ores yielded Re–Os model ages of 137.8–133.1 Ma (isochron age, 135.9 ± 1.4 Ma). These ages were consistent with the zircon U–Pb age of quartz monzodiorite (137.8 ± 1.7 Ma). A total of 146 in situ S isotope analyses yielded δ34S values (1.9–7.4 ‰) indicating that the sulfur was derived from a magmatic source. Therefore, the Dongguashan deposit resulted from Early Cretaceous magmatism rather than submarine exhalative sedimentary processes. The fluctuations in S isotopes of sulfides across the three mineralization types are attributable to different factors (pH, temperature, and oxygen fugacity) during the evolution of hydrothermal ore-forming fluids. This study demonstrates the importance of geochronology of mineralization and in situ sulfur isotope analysis under robust geological and petrographic frameworks, which can yield information about the ore-forming processes and ore genesis.

U–Pb LA-ICP-MS and Re–Os dating of wolframite and molybdenite: Constraints on multiple mineralization and cooling history (40Ar/39Ar) for the magmatic–hydrothermal system at Borralha, northern Portugal

The Borralha area (Iberian Massif, Portugal) reflects a long-lived and multiphase magmatism (ca. 316 to 300 Ma), characterized by three types of granite emplacement during two different extensional events (E1 and E2) and one compressional event (C3) within the Variscan orogeny. The W (Cu) mineralization styles correspond to veinlets and quartz veins (i.e., São António and Santa Helena), and disseminations in the Santa Helena breccia pipe. Molybdenite coexists with an Fe-bearing wolframite–quartz assemblage in the Venise breccia pipe and quartz veins (i.e., São José and São Paulo).The geochemistry and geochronology of wolframite and molybdenite samples were studied by electron probe microanalysis (EPMA), in-situ U–Pb laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) and Re–Os thermal ionization mass spectrometry (TIMS). The wolframite yields a U–Pb age (sample WBV1) of 315.2 ± 4.7 Ma (2σ), representing the first recognized episode of W deposition in the Iberian Massif. Wolframite samples (WBV1, WB1, and WB4) have a ferberite composition with a hübnerite/ferberite ratio of < 29. High amounts of Nb (up to 3703 ppm) with low Ta (up to 123 ppm) and REEs (up to 11.4 ppm) and conversely, low amounts of Nb (up to 471 ppm) with high Ta (up to 190 ppm) and REEs (up to 53.7 ppm) were measured in wolframite samples. The REEs normalized patterns of the wolframite samples record a mixed signature. Large and positive Eu/Eu* and Er/Er* anomalies were identified (sample WBV1), whereas negative Ce/Ce* and Nd/Nd* anomalies were observed in samples WB1 and WB4.Molybdenite Re–Os dating yields absolute ages ranging from 305.1 to 303.8 ± 2.2 Ma (2σ), which are coeval with the emplacement of E2 biotite granite (Penedos; I-type; <305 Ma). Low amounts of Re (<1 ppm), W, Co, Ni, As, Cu, Bi, Fe, Mn V and Se (<0.005 wt%) were detected in the molybdenite structure.Constraints between the timing of W- and Mo-deposition and a protracted cooling history of the host rocks are confirmed by 40Ar/39Ar white mica dating. The 40Ar/39Ar ages obtained for secondary white micas collected from Mo veins (Venise breccia pipe; 277 ± 3 and 287 ± 4 Ma 2σ) and W (Cu) dissemination (Santa Helena breccia pipe; 287 ± 2 and 279.0 ± 6 Ma 2σ) record the isotopic resetting by later hydrothermal overprints and cooling /exhumation history after E2 Gerês biotitic granite emplacement.The W-ore deposition did occurred during the final E1 extensional tectonic stage (315 Ma) and E2 extensional tectonic stage for Mo-ore deposition, where a temporal offset was needed for the adjustment of tectonic conditions after the C3 compressional and E2 extensional stage started.

Molybdenite Reference Materials for In SituLA‐ICP‐MS/MS Re‐Os Geochronology

Re‐Os isotope‐dilution geochronology has been widely used to date the timing of molybdenite, pyrite and chalcopyrite formation across a variety of geological settings. However, in situ methods have been impeded by the isobaric interference of 187Re on 187Os. In situ Re‐Os geochronology using LA‐ICP‐MS/MS has been shown to be a useful technique to chemically separate Os from Re, as Os reacts with CH4 to create higher‐mass reaction products, which can then be measured with minimised interference of 187Re. However, application of the method requires matrix‐matched primary reference materials, e.g., age‐homogenous molybdenite amenable to laser ablation. Here, we characterise and present two new molybdenite mineral reference materials for in situ Re‐Os geochronology by LA‐ICP‐MS/MS, verified by ID‐TIMS Re‐Os measurements. We also present case studies from molybdenite samples with varying Re mass fractions and Re‐Os age mapping. The method provides accurate and precise age data, with excellent precision for high Re samples. The benefits of the LA‐ICP‐MS/MS approach include: (1) simple sample preparation, (2) rapid data acquisition, (3) targeting of specific textural domains including growth zones and (4) the ability to simultaneously collect trace elements used to link the timing and conditions of ore‐formation.

Multiple isotopic dating constraints on diverse W metallogeny in the Baiyunxian ore field, South China

The Baiyunxian ore field, a large tungsten ore filed in the Nanling Metallogenic Belt of South China, hosts a variety of tungsten deposits such as the Dapu (quartz wolframite vein type), Chashanjiao (skarn type), Toutianmen (greisen type), and Dashan (quartz scheelite vein type). However, precise mineralization ages of these deposits remain poorly constrained and this has long vexed a better understanding of genetic relationships between diverse W mineralization types and the spatially associated Jiufeng granitic complexes. Here, we report firsthand zircon U–Pb, monazite U–Pb, garnet U–Pb, cassiterite U–Pb, and molybdenite Re–Os ages of different granites and ores from the Baiyunxian ore field. The Jiufeng granitic complexes consists of phase Ⅰ biotite granite (P1), phase Ⅱ two-mica granite (P2), and phase Ⅲ granitic dikes (P3, including greisen W ore). Zircons from P1 granite define a concordant U–Pb age of 166.0 ± 0.9 Ma (MSWD = 1.1). Monazites from P2 granite yielded a Tera–Wasserburg lower intercept age of 159.2 ± 0.7 Ma (MSWD = 0.45). In addition, zircons and monazites from P3 granite in the Toutianmen deposit yield a concordant U–Pb age of 154.7 ± 1.3 Ma (MSWD = 1.3) and a Tera–Wasserburg lower intercept age of 156.6 ± 1.9 Ma (MSWD = 0.14), respectively, suggestive of multi-stage emplacement processes of the Jiufeng complexes. Ten molybdenite samples from the Dapu deposit generate an isochron age of 156.0 ± 3.0 Ma (MSWD = 0.93). In situ garnet and cassiterite LA-ICP-MS U–Pb dating results of the Chashanjiao skarn deposit yield lower Tera–Wasserburg intercept ages of 155.3 ± 1.2 Ma (MSWD = 1.6) and 153.4 ± 3.7 Ma (MSWD = 1.3), respectively. These dating results indicate that different W mineralization events in the Baiyunxian ore field intensively occurred in the Late Jurassic (∼159–153 Ma). Despite a close spatial relationship between various W orebodies and P1 granite, the geochronological results demonstrate that extensive W metallogeny in the Baiyunxian ore filed likely occurred later than P1 granite and contemporaneous with P2–3 granites. In addition, scheelites from the four deposits have similar REE patterns that are characterized by weak MREE enrichment, despite few exceptions being found in scheelites from the Dashan and Chashanjiao deposits. This suggests that the diverse W metallogeny in the Baiyunxian ore field were derived from the same magmatic hydrothermal system and changed as the ore-forming fluid evolved. Multidisciplinary evidence indicates that the Late Jurassic highly evolved P2–3 granites of the Jiufeng complexes were crucial to W mineralization in the Baiyunxian ore field and the lithology of wall rocks exerted first-order control of W mineralization types.

In situ precise determination of stable Mo isotope ratios in molybdenite by femtosecond LA-MC-ICP-MS

We developed a new method for in situ measurement of Mo stable isotope ratios using femtosecond laser ablation coupled with MC-ICP-MS. Additionally, experiments were conducted on nine natural molybdenite samples from different ore deposits in China.

The Ahadawa deposit—A newly discovered porphyry Cu–Mo system in the North Qaidam, Northern Qinghai-Tibet Plateau, NW China

Ongoing exploration in the North Qaidam, Northern Qinghai-Tibet Plateau, NW China, has led to the identification of a porphyry Cu-Mo system centered on Ahadawa. In this study, we conducted a detailed geochronological and geochemical study on porphyritic monzogranite from the Ahadawa deposit, which hosts the Cu-Mo mineralization. The weighted mean zircon U-Pb ages for three mineralized porphyritic monzogranite samples from different sites range from 218.8 ± 1.2 Ma (MSWD = 1.5) to 224.7 ± 1.6 Ma (MSWD = 1.8), and finally to 233.1 ± 0.9 Ma (MSWD = 1.4, n = 23). These results, combined with antecrystic grains as old as ∼ 245.7 Ma, collectively indicate more than 25 Ma multi-stage magmatic emplacement activity in the Ahadawa deposit. Corresponding to complex magma episodes, six studied molybdenite samples yielded variable Re-Os model ages ranging from 436.7 ± 6.6 to 232.6 ± 1.2 Ma, with the three youngest dates constraining a weighted mean Re-Os age of 234.0 ± 6.8 Ma. The 234 Ma mineralization age is consistent with the observed Late Triassic magmatism, whereas the Re-Os model ages of 436.7 to 245.7 Ma, if they remain robust through future investigation, may highlight a long-lived hydrothermal activity in the Ahadawa deposit. Whole-rock and zircon compositions indicate that the Late Triassic porphyries occurring at the surface display distinct geochemical features, with the early porphyritic monzogranite of 233.1 Ma characterized by much higher whole-rock Sr/Y, and zircon Eu/Eu* and Ce/Ce* than the younger (218.8 Ma and 224.7 Ma, respectively) porphyritic monzogranite. This suggests that the Late Triassic magmas were initially characterized by high water content and high oxidation state and the differences between the old and two younger groups might be related to plagioclase-dominated fractionation. The finding of the Ahadawa porphyry system highlights the need for ongoing exploration (especially in poorly studied remote areas) and systematically geochronological and geochemical studies to constrain the temporal and spatial evolution of mineralized episodes within a complex, protracted magmatic history.

Ore‐forming process within the Hongyuan reduced porphyry Mo–Cu deposit, West Junggar, NW China

The Hongyuan porphyry Mo–Cu deposit (PMCD) is a rare example of a “reduced” deposit, in contrast to classical oxidized porphyry Cu or Mo–Cu deposits. It is characterized by an ilmenite–series I–type felsic granitoid intrusion, reduced ore‐forming fluids with methane‐rich fluid inclusions, and widely distributed primary pyrrhotite. Mo–Cu mineralization in the Hongyuan PMCD occurs as disseminated in porphyry, granular in miarolitic cavity, and vein‐type in the quartz vein. These three types of mineralization are generally produced in the late magmatic period, magmatic‐hydrothermal transition period, and hydrothermal period, respectively. Molybdenite from miarolitic cavities shows a greater contribution from mantle fluid, as evidenced by mantle He proportions of 37.6%–16.8%. Molybdenite in quartz veins has relatively lower mantle He proportions of 1.63%–10.5%, indicating a predominantly crustal fluid source. The 3He/4He variations of these two groups of molybdenite illustrate an increasing input of crustal fluid during the magmatic to hydrothermal transition. Molybdenite samples from miarolitic cavities and quartz veins yield a Re‐Os model age of 300.5 ± 3.7 Ma, which is consistent with the U–Pb ages of zircons in the wallrock porphyries (300–302 Ma). This further indicates simultaneous diagenesis accompanied by mineralization. The Sr–Nd isotopic compositions (initial 87Sr/86Sr: 0.703404–0.703552; initial 143Nd/144Nd: 0.512585–0.512655; εNd[t]: +6.56 to +7.90) and young T2DM model ages (421–531 Ma) of the Hongyuan porphyries suggest that these rocks were derived from partial melting of the basaltic lower crust. We propose that mantle‐derived fluids rose up and mixed with fluids from the lower crust under an extensional tectonic setting, forming mantle‐like Sr–Nd–He–Ar isotopic compositions. The pre‐mineralization stage of the Hongyuan reduced PMCD is marked by quartz‐molybdenite ± K‐feldspar ± pyrite veins or veinlets and miarolitic cavities in the intensively potassic alteration zone. These veins formed at high temperatures (400–476°C) and high salinities (47.5–56.6 wt.%). The syn‐mineralization stage is the main metallogenic stage represented by numerous quartz‐molybdenite ± pyrrhotite veins associated with moderate to high temperatures (248°C–424°C) and low to high salinities (1.57–50.1 wt.%). The post‐mineralization stage is characterized by low temperatures (104–270°C) and low salinities (0.35–8.81 wt.%). Fluid immiscibility, mixing with meteoric water, ore fluid‐wall rock interactions, and decreasing temperature and salinity have played important roles during molybdenum mineralization.

Geology of Porphyry Cu-Au and Epithermal Cu-Au-Ag Mineralization at Filo del Sol, Argentina-Chile: Extreme Telescoping During Andean Uplift

Abstract Filo del Sol is a composite porphyry-epithermal deposit, straddling the frontier between Argentina and Chile at latitude 28°29′ S, that has attracted a great deal of recent attention because of several drill intersections in excess of 1 km long with unusually high Cu, Au, and Ag grades. The deposit is part of the 8.5-km-long, N- to NE-trending Filo del Sol alignment of porphyry and high-sulfidation epithermal centers, which, in turn, is located in the newly defined Vicuña metallogenic belt that unites the well-known late Oligocene to middle Miocene Maricunga and El Indio belts. The deposit is hosted by Permian felsic volcanic rocks intruded by Triassic monzogranite and, nearer the surface, by shallowly dipping Late Cretaceous volcano-sedimentary rocks. These lithologic units were intruded by several generations of mafic dikes and high-level sills and, in the middle Miocene, by a parallel swarm of composite diorite porphyry dikes. An intermineral magmatic-hydrothermal breccia body is closely associated with the porphyry dikes and subsequently cut at shallow levels by a smaller, finer-grained breccia of phreatic and, possibly, phreatomagmatic origin. Early Cu-Au mineralization, mainly as chalcopyrite, is associated with K-feldspar- and biotite-bearing potassic alteration and accompanying A-type quartz-veinlet stockworks. The potassic zone was massively overprinted and extensively reconstituted by a zone of vuggy residual quartz and silicification in the core of the deposit, flanked by quartz-alunite as part of a more extensive lithocap. These alteration types host high-sulfidation Cu-Au-Ag mineralization as pyrite with early enargite and later bornite, chalcocite, covellite, and numerous Ag-bearing sulfosalts, with the highest grades typically confined to vuggy residual quartz. Largely barren, steam-heated alteration is preserved above and overprinted on the lithocap. The results of radiometric dating (six U-Pb and 22 Re-Os ages) show that porphyry intrusion and potassic alteration began at ~15 Ma and lasted for nearly 1 m.y., although most of the molybdenite samples reported ages from 14.7 to 14.4 ± 0.06 Ma. This short interval coincided with a pulse of regional compressive tectonism accommodated by high-angle, thick-skinned, reverse faulting of basement-cored blocks, and concomitant uplift and exhumation. This uplift gave rise to ~1 km of erosion during formation of the Filo del Sol deposit, thereby accounting for the extreme telescoping of high-sulfidation over porphyry mineralization. Spatial association of these middle Miocene intrusion centers with dated middle Permian and Eocene mineralization suggests deep-seated structural control of the Filo del Sol alignment. Ongoing supergene processes under low-pH conditions produced a near-surface resource dominated by chalcanthite, with minor underlying chalcocite enrichment, as well as partially oxidizing a shallow zone of high-grade Ag mineralization.

Geology, molybdenite Re-Os age, H-O-S-Pb isotopes, and fluid inclusion features of the Maodeng Mo-Bi-Sn-Cu deposit, Inner Mongolia

Maodeng deposit is a large-sized Mo-Bi-Sn-Cu deposit located in the Xinlinhot of Inner Mongolia in the southern segment of the Great Xing’an Range. The ore-forming elements in the deposit are found in the volcanic breccia of Lower–Middle Permian Dashizhai Formation and granite porphyry of the Alubaogeshan complex, constituting distinct regional mineralization zones such as hydrothermal vein-type of Sn-Cu orebodies in the upper parts and stockworks, veinlets and disseminated-type of Mo-Bi orebodies in the lower parts. This paper has conducted an integrated study using a comprehensive field survey, molybdenite Re-Os age, fluid inclusion, and isotopic (O, H, S, and Pb) analyses. The mineralization in the deposit can be divided into four stages, which are molybdenite-native bismuth-quartz (stage I), cassiterite-wolframite-topaz-quartz (stage II), chalcopyrite-sphalerite-galena-fluorite-sericite-quartz (stage III) and stibnite-pyrite-quartz-fluorite (stage IV). The Re-Os isochron age of four molybdenite samples was estimated as 139.2 ± 3.9 Ma, indicating the deposit was formed during the Early Cretaceous. The Maodeng deposit is characterized by three kinds of fluid inclusions (FIs): liquid-rich two-phase, vapor-rich two-phase, and daughter mineral-bearing three-phase FIs. The homogenization temperatures for the FIs of stages I through IV are 292–387 °C, 222–333 °C, 172–252 °C, and 122–197 °C, with calculated salinities of 4.2–43.6 wt%, 2.1–38.9 wt%, 1.9–33.6 wt% and 0.7–5.1 wt% NaCl equiv., respectively, showing the gradual reduction in temperature and salinity of hydrothermal fluids. Hydrogen and oxygen isotopic data of quartz indicate that the dominant origin of the ore-forming solutions from deep granitic intrusions followed by their dilution by limited meteoric water. The sulfides have δ34S values ranging from − 6 ‰ to − 0.49 ‰, and have 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios similar to those of K-feldspars from the Alubaogeshan pluton, suggesting the primary origin of ore-forming materials of the Maodeng deposit are magmatic. Molybdenite and native bismuth may precipitate primarily by fluid boiling, chalcopyrite could deposit mainly by fluid mixing, and cassiterite precipitate mainly through fluid boiling and mixing.

Re Variation Triggered from the Paleo-Pacific Plate Evolution: Constrains from Mo Polymetallic Deposits in Zhejiang Province, South China Mo Province

Although highly dispersed, critical Re metal has attracted lots of attention from geoscientists, the controlling factors of Re-content variation are not completely understood, especially with regards to the genetic relationship between Re-bearing Mo polymetallic deposits and plate subduction evolution. It is well documented that the South China Mo Province, in Zhejiang Province, is characterized by multi-stage Mo polymetallic mineralization associated with Paleo-Pacific plate subduction. The Xianlin Mo(Cu)–Fe deposit occurs in Western Zhejiang as porphyry mineralization or skarn mineralization between the granodiorite and limestone. Zircon U–Pb analysis of the ore-forming granodiorite yields a Concordia age of 150.8 ± 1.1 Ma. Six molybdenite samples have relatively high Re contents (128.9~155.7 ppm) and deliver a weighted mean model age of 149.6 ± 1.3 Ma. These geochronological data suggest the Xianlin polymetallic mineralization was genetically related to the granodiorite in the Late Jurassic. Moreover, a new compilation of reliable Re contents and Re–Os isotope age data in Zhejiang Province indicates a decreasing trend in Re contents of molybdenite from the Jurassic Fe-/Cu-dominated Mo mineralization stage to the Cretaceous PbZn-enriched Mo mineralization stage in the South China Mo Province. Based on previously proposed models relating tectonic, magmatic, and hydrothermal processes, it is suggested that the Jurassic Re-enriched Mo mineralization, associated with I-type granitoids, formed in a compressive setting during the low-angle subduction of the Paleo-Pacific slab, whilst the Cretaceous Re-poorer Mo/Mo–Pb–Zn mineralization, related to both I- and A-type granitoids, formed in an extensional back-arc setting triggered by the rollback of the Paleo-Pacific slab.

The Jurassic Gangmei Mo-W deposit in Guangdong Province and its implication for Mo-W mineralization in South China

South China developed large-scale Mesozoic magmatism and polymetallic mineralization, especially Jurassic W-Sn and Mo-W mineralization. Compared with W-Sn deposits, Mo-W deposits in South China have received less attention. The recently discovered Gangmei Mo-W deposit, which occurred in Guangdong Province, is the southernmost Jurassic Mo-W mineralization in South China. Here, we report the molybdenite Re-Os isotopic age of the Gangmei deposit and compile the Mo-W- and W-Sn-associated deposits in South China and their Re concentrations in molybdenites, aiming at constraining the ore-forming age of the Gangmei deposit, the scope of Mo-W mineralization in South China and the possible controlling factors of different mineralization types. Four molybdenite samples from the Gangmei deposit were chosen for Re-Os isotopic dating. The Re-Os model ages vary from 162.6 ± 1.6 Ma to 164.1 ± 1.6 Ma with a weighted mean age of 163.1 ± 1.4 Ma and yield an isochron age of 162.2 ± 4.1 Ma (MSWD = 1.01), consistent with the emplacement age of the Gangmei intrusion, indicating a genetic relationship between magmatic activity and mineralization. This age also agrees well with the large-scale Jurassic Mo-W- and W-Sn-associated mineralization in South China, suggesting that the scope of Jurassic Mo-W-associated mineralization can reach the southernmost part of South China. Rhenium concentrations in molybdenites from Jurassic Mo-W-associated and W-Sn-associated deposits in South China suggest that their magma sources are different, and Mo-W-associated deposits may involve more mantle-derived materials. In addition, oxygen fugacity may be another factor controlling different types of mineralization in South China.

Geochemical, zircon U–Pb–Hf–O isotopic evidence and molybdenite Re–Os dating from the Cuojiaoma batholith, eastern Tibetan Plateau: Implications for molybdenum potential and tectonic evolution

Subduction of oceanic plates beneath continental lithosphere is critical for understanding tectonic evolution and evaluation of prospecting and exploration. Within the Yidun Terrane (YDT) of southwestern China, a number of Mesozoic to Cenozoic granitoid intrusions are exposed and they are useful for investigating the tectonic evolution of the Paleo-Tethys system. However, Mesozoic magmatism of the northern portion of the YDT, remains ambiguous regarding to their magmatic spatial–temporal evolution and their mineralization potential. As the largest pluton in the northern YDT, the Cuojiaoma batholith mainly consists of monzogranite and granodiorite. In this study, we present new zircon U–Pb and molybdenite Re–Os ages, whole-rock geochemical, and zircon Hf–O isotopic data for the Cuojiaoma batholith. LA-ICP-MS zircon U-Pb dating of granodiorite and monzogranite exhibit ages of 221.8 ± 1.4 Ma (n = 22, MSWD = 2.4) and 216.7 ± 2.2 Ma (n = 14, MSWD = 0.03), respectively. A total of 9 molybdenite samples differing Re-Os model ages of 205.4 ± 3.3 and 220.6 ± 5.5 Ma, yield a robust weighted mean model age of 209.9 ± 1.8 Ma (MSWD = 2.4, n = 9) representing the depositional age of molybdenite. The monzogranite and granodiorite’s mineralogical and geochemical characteristics indicate they are classified as (medium-) high-K calc-alkaline and metaluminous to weakly peraluminous I-type granite. Geochemically, they are enriched in large-ion lithophile elements (LILEs, e.g., Rb, U, K) and light rare earth elements (LREEs), and depleted in high-field-strength elements (HFSEs, e.g., Nb, Ta, Ti and P) and heavy rare earth elements (HREEs), and contain distinctly or slightly negative Eu anomalies and no significant Ce anomalies, indicating an affinity to classical island arc magma. Combined with their negative zircon εHf(t) values (−16.24 to −2.49 and −16.41 to −1.43) and two-stage Hf model ages (2019–1255 Ma and 2027–1200 Ma), plus their zircon δ18O values, which range from 5.96 to 8.01 and from 5.05 to 7.61 for monzogranite and granodiorite, respectively, these geochemical indexes indicate that the Cuojiaoma batholith shares similar petrogenesis to other intrusions within the YDT. The formation of the early granodiorite may be genetically related to the slab subduction and is most likely formed by mixture of lower crustal melts and mafic magma derived from partial melting of mantle wedge induced by the influx of slab derived melt (fluid). Subsequent slab break-off and the upwelling asthenosphere at ∼ 216 Ma to 210 Ma led to high heat flow and extensive melting of the overlying mantle wedge, followed by the highly crystallization differentiation, which finally contributed to the monzogranite and the subsequential disseminated molybdenite in a post-subduction extension setting. The northern YDT possesses high Mo metallogenic prospectivity, especially for the magmatic activity that dominantly by lower crustal melt and genetically related to the slab break-off occurred at ∼ 216 Ma and represented by the highly fractionated granite derived from the large Cuojiaoma granitic batholith.

Periodic and non-periodic stacking in molybdenite (MoS2) revealed by STEM

Abstract Polytypism is a typical feature of layered minerals with differences only in stacking sequences. There is no obvious “phase” boundary among different polytypes, although the frequency of polytypes occurrence is related to its crystallization environment. In the past decades, X-ray studies of molybdenite specimens from a variety of geological environments have revealed that most molybdenite crystals contain both 2H1 (hexagonal) and 3R (rhombohedral) polytypes. However, the stacking sequences of these molybdenite polytypic intergrowths and their formation mechanism are not well understood. Here, we report stacking faults and domains of long-period polytypes identified by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) in a molybdenite sample from a carbonatite vein in the Huanglongpu Mo-Pb ore deposit in Qinling orogenic belt, Northern China. Several layers of disordered domains intergrown with ordered 2H1 domain were recognized based on the contrast in HAADF image with one-dimensional lattice fringes. In addition, a 30-layer long-period polytype was unambiguously identified by a STEM image. The stacking sequences of 4-, 6-, and 8-layer disordered domains and the 30-layer long-period polytype were further examined using HRSTEM images at the atomic resolution. A 2H3 polytype with three repetitions was also discovered in the sample. We propose that non-equilibrium conditions related to the fluctuation of fluid composition during crystallization resulted in the oscillation of 2H1 and 3R polytypes and intergrowth of various disordered domains. More broadly, our study demonstrates that HAADF-STEM imaging method may be applicable for studying other disordered layered crystals and twinned minerals.

Re‐Os Isotopic Age of Molybdenite of the Jingren Deposit and its Mineralogical Significance of Magnetite, Pyrite and Chalcopyrite

AbstractThe Jingren deposit is part of the Qimantage metallogenic belt within the eastern Kunlun orogenic belt, the largest metallogenic belt in Qinghai Province, northwestern China. Exploration data show that the metal resources of the Jingren deposit are greater than 93000 t in a mining area of 76.15 km2, which indicates significant exploration potential in the near future. Three W–E‐trending faults, F1‐3, dominate the extension of the mineralization zone, which consists of chalcopyrite, pyrite, magnetite, galena, sphalerite, and molybdenite as well as bismuth‐bearing minerals. The deposit contains a large amount of late Triassic intrusive rocks, however, previous research did not reach a consensus on the timing or the origin of the mineralization owing to a lack of geochronological data and poor exposure conditions. In the present study, Re‐Os isotopic dating from six molybdenite samples collected from a borehole of the granodiorite in the Jingren deposit using negative thermal ionization mass spectrometry (NTIMS) showed 187Re and 187Os concentrations of 0.26–4.40 ppm and 1.03–16.46 ppb, respectively, with an initial 187Os/188Os value of 0.06 ± 0.19. This proves that the Jingren deposit has a metallogenic age of (225 ± 4) Ma and is the product of united mineralization of the Qimantage metallogenic belt and that the Jingren deposit might actually be an Indosinian metallogeny. In addition, the Re content of these samples, at 0.42 ppm to 7.00 ppm shows that the mineralization was derived mainly from a crustal source. Furthermore, electron probe microanalysis (EPMA) conducted on chalcopyrite obtained from 22 metallic mineral samples revealed (Fe + Cu)/S ratios of 1.801–1.947 with an average of 1.852, which is lower than the ideal value (1.875). Besides, the main ore body formed in a relatively higher temperature environment than the surrounding rocks in the Jingren deposit. These data indicate that the Jingren deposit formed in a metallogenic environment at lower temperature. Moreover, according to the TiO2‐Al2O3‐(MgO + MnO) and TiO2‐Al2O3‐MgO genetic classification diagram for magnetite, the Jingren deposit most likely belongs to the skarn family. In addition, the Co‐Ni‐As genetic classification diagram of the pyrite indicates sedimentary and skarn genetic characteristics.

Theoretical and experimental investigation of disodium carboxymethyl trithiocarbonate in Cu-Mo flotation

As ore grades in the mineral industry decrease and ores become more complex and polymetallic, froth flotation becomes increasingly important in separating and producing a saleable product. In the chalcopyrite-molybdenite flotation industry, depressants are critical in achieving the necessary metal separation. NaHS is the predominant reagent used to depress copper and iron sulfides and thereby enable molybdenum flotation recovery and grade. However, these inorganic reagents have increasing regulations governing their use and have high consumption rates collectively meaning that the use of alternative reagents, especially organic depressants, is needed. Disodium Carboxymethyl Trithiocarbonate (Orfom® D8) is one such organic depressant. This study will report on research conducted with Orfom® D8 including bench-scale flotation as well as simple kinetic test (SKT) flotation of bulk chalcopyrite-molybdenite concentrate obtained from an operating North American process. Density Function Theory (DFT) molecular modeling and zeta potential measurements of pure chalcopyrite (CuFeS2) and molybdenite (MoS2) samples were used to help corroborate the flotation results.

Genesis of the Yanghuidongzi Cu deposit, NE China: Constraints from H-O-Pb isotopic compositions and geochronological study

• The Yanghuidongzi Cu deposit classified as a porphyry type Cu deposit. • H-O isotopes indicate a mixing of magmatic water and meteoric water for ore fluids. • Pb-Re isotopes indicated a deep seated magma mixed with crustal materials for ore metals. • The Yanghuidongzi Cu deposit formed during Early Jurassic . The newly-discovered Yanghuidongzi porphyry Cu deposit is located in the southeastern part of Heilongjiang Province in NE China and represents one of the rare Jurassic porphyry Cu deposits within the easternmost segment of the Central Asian Orogenic Belt (CAOB). The Cu mineralization occurs as veins and disseminations hosted by granodiorite porphyry, associated with typical porphyry copper deposit alteration zoning, which is characterized by from an inner K-silicate zone through to a quartz–sericite zone to an outer propylitic zone, the K-silicate alteration and quartz–sericite alteration are closely related to mineralization. LA-ICP-MS zircon U-Pb data, sericite Ar-Ar and Molybdenite Re-Os data, and H-O and Pb isotopic compositions are used to constrain the ore-forming age and genesis of the Yanghuidongzi Cu deposit. LA-ICP-MS U-Pb dating of zircons from three granodiorite porphyry samples yielded weighted mean 206 Pb/ 238 U ages of 194.3 ± 1.2 Ma, 192.0 ± 2.0 Ma, and 194.6 ± 2.1 Ma respectively, whereas zircon U-Pb age of granodiorite in the study area yielded weighted mean 206 Pb/ 238 U age of 199.5 ± 1.5 Ma that are interpreted to be the emplacement age of these intrusions. 40 Ar- 39 Ar dating of sericite from a quartz-pyrite vein and a quartz-polymetallic sulfide vein yielded plateau ages of 193.9 ± 2.1 Ma and 193.6 ± 1.9 Ma, respectively, whereas five molybdenite samples yielded a Re-Os isochron age of 194.8 ± 2.1 Ma, with a weighted mean model age of 193.6 ± 1.2 Ma. Mineralization ages are consistent with the emplaced ages of the granodiorite porphyry within the analytical uncertainties, indicating that the Cu mineralization is genetically related to the granodiorite porphyry. The fluid δ 18 O fluid and δ 18 D fluid values range from −4.22‰ to 6.5‰ and from −92.8‰ to −65.7‰, respectively, indicating that the ore fluids were mixtures of magmatic and meteoric water. The 206 Pb/ 204 Pb, 207 Pb/ 204 Pb, and 208 Pb/ 204 Pb values of the pyrite and chalcopyrite are 17.547–18.327, 15.446–15.505, and 37.408–38.113, respectively, suggesting a common, magmatic source for the sulfur. Taking Re (6.75–29.53 ppm) data into consideration, the sources of ore-forming materials may be from a mixture of crustal and mantle sources. Combining our new data with the Jurassic regional tectonic setting, the Yanghuidongzi Cu deposit and the related granitoids formed in a compressional tectonic setting are associated with the subduction of the Paleo-Pacific Plate beneath the Eurasian continent.