Metallogenic Province Research Articles

Genesis of the Qilinchang Pb–Zn deposit, southwestern China: Evidence from mineralogy, trace elements systematics and S–Pb isotopic characteristics of sphalerite

The Qilinchang (Pb–Zn)–Ag-Ge deposit of the Yangtze Platform, southwest China are hosted in the Early Carboniferous carbonate rocks of the Baizuo Formation. The deposit is located within the Sichuan-Yunnan-Guizhou (SYG) metallogenic province, which is western bounded by the Yangtze Platform in the southwestern part of China. Ore minerals are sphalerite, galena, pyrite, chalcopyrite, and marmatite, whereas gangue minerals are dolomite, calcite, and quartz. This study highlights the results of sphalerite chemistry analyzed by electron microprobe analyzer (EPMA), the laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and isotopic analysis. These techniques were used to investigate the major and trace concentrations in sphalerite from the Qilinchang deposit, in an attempt to provide noteworthy discernments into the ore-forming temperature and metal sources of the deposit. The calculated FeS (mole %) results obtained from Fe (wt. %) with the assumption that the sphalerite is stoichiometric in composition range from 0.02 to 13.48 mol % and mode at 3 mol %. This low FeS content falls within the bornite + pyrite + chalcopyrite field on the Fe–Zn–S system suggesting an increase in sulfur activity. The application of Ga/Ge ratios in sphalerite against the formation temperature was used to determine the homogenization temperature of this deposit. This expression is based on the existing Al/Si geothermometers as (Al/Si)total atomic ratio as a function of temperature calculated using available constants of hydrolysis reactions. The log10 (Ga/Ge) ratios calculated for this study range from −2.8 to 0.87, corresponding to formation temperatures of 100–227 °C, with an average of 180.3 °C. Likewise, correlation between PC1* and the homogenization temperature indicated that the calculated formation temperatures for this study ranged from 119.3 to 217.9 °C, which suggests that the deposit is sourced from a low-temperature environment. The δ34S of sphalerite is related to the thermochemical sulfate reduction (TSR) of Carboniferous seawater sulfate and are mainly derived from evaporites in the host strata producing H2S−rich fluid by TSR with restricted inducement from mantle-derived sulfur. The homogenous composition of Pb isotopic data of sphalerite indicates that the metals were predominantly originated from the basement rocks of the Mesoproterozoic-early Neoproterozoic rocks of the Kunyang Group. From these geochemical signatures, it can be inferred that the Qilinchang deposit was not linked to magmatic activities. It is proposed that the ore-forming fluids responsible for the formation of the deposit were generated from a low-temperature environment. Economic potential reveals the most important attributes of this deposit are high Zn and Pb grade (approximately 17.5% Zn and 6.6% Pb, 3.32 Mt of metal). Overall, the mineralization of the Qilinchang Pb–Zn deposit shows it a high-grade remarkable Pb–Zn deposit transiting between MVT and high-temperature carbonate-replacement Pb–Zn deposits. We suggest that the determination of the genetic type of this exceptional deposit is important to the research and exploration of similar Pb–Zn deposits in other metallogenic provinces of China.

The Origin of Carbonate Components in Carbonate Hosted Pb-Zn Deposit in the Sichuan-Yunnan-Guizhou Pb-Zn Metallogenic Province and Southwest China: Take Lekai Pb-Zn Deposit as an Example

The Lekai lead–zinc (Pb-Zn) deposit is located in the northwest of the Sichuan–Yunnan–Guizhou (SYG) Pb-Zn metallogenic province, southwest China. Even now, the source of the metallogenic fluid of Pb-Zn deposits in the SYG Pb-Zn metallogenic province has not been recognized. Based on traditional lithography, rare earth elements (REEs), and carbon–oxygen (C–O) isotopes, this work uses the magnesium (Mg) isotopes of hydrothermal carbonate to discuss the fluid source of the Lekai Pb-Zn deposit and discusses the fractionation mechaism of Mg isotopes during Pb-Zn mineralization. The REE distribution patterns of hydrothermal calcite/dolomite are similar to that of Devonian sedimentary carbonate rocks, which are all present steep right-dip type, indicating that sedimentary carbonate rocks may be serve as the main source units of ore-forming fluids. The C–O isotopic results of hydrothermal dolomite/calcite and the δ13CPDB–δ18 OSMOW diagram show that dolomite formation is closely related to the dissolution of marine carbonate rocks, and calcite may be affected to some extent by basement fluid. The Mg isotopic composition of dolomite/calcite ranges from −3.853‰ to −1.358‰, which is obviously lighter than that of chondrites, mantle, or seawater and close to that of sedimentary carbonate rock. It shows that the source of the Mg element in metallogenic fluid of Lekai Pb-Zn deposit may be sedimentary carbonate rock rather than mantle, chondrites, or seawater. In addition, the mineral phase controls the Mg isotope fractionation of dolomite/calcite in the Lekai Pb-Zn deposit. Based on the geological, mineralogical, and hydrothermal calcite/dolomite REE, C–O isotope, and Mg isotope values, this work holds that the mineralization of the Lekai Pb-Zn deposit is mainly caused by basin fluids, influenced by the basement fluids; the participation of basement fluids affects the scale and grade of the deposit.

Genetic significance of trace elements in hydrothermal quartz from the Xiangzhong metallogenic province, South China

Despite the Xiangzhong metallogenic province being globally the most important ore-concentrated area of antimony (Sb) mineralization, the genesis of Sb-(Au-W) deposits in this region is still under debate. In this study, trace element compositions of hydrothermal quartz from four representative Sb-(Au-W) deposits (Xikuangshan, Woxi, Banxi, and Zhazixi) in the Xiangzhong metallogenic province have been investigated to constrain the origin of ore-forming fluids and physiochemical conditions of Sb mineralization. The fsLA-ICP-MS data indicate that Li, B, Na, Al, P, K, and Sb are relatively enriched in quartz, probably mainly incorporated into the quartz crystal lattice, and dominated by the coupled substitution of (Al3+, Sb3+, B3+) + (Li+, Na+, K+, H+) ↔ Si4+ and (Al3+, Sb3+, B3+) + P5+ ↔ 2Si4+. In the Xikuangshan Sb deposit, charge-neutrality conditions of cations reveal that (Al3+, Sb3+) + Li+ ↔ Si4+ is the most important substitution mechanism in quartz from early-stage Sb mineralization (quartz-stibnite veins), whereas (Al3+, Sb3+) + (Li+ + H+) ↔ Si4+ may control the trace element contents in quartz from late-stage Sb mineralization (calcite-quartz-stibnite veins). The relatively high Al content and the low variability in trace element content suggest that quartz from the Xikuangshan Sb deposit may have precipitated from a relatively acidic and stable ore-forming fluid. Combined with the high Sr and Rb contents of quartz, a plausible explanation is that acidic hydrothermal fluids promoted water–rock reaction that dissolved large amounts of Sr and Rb, resulting in the high Al, Rb, and Sr contents in crystallized quartz from the Xikuangshan Sb deposit. In contrast, the relatively low but inhomogeneous Al content indicates that quartz from the Woxi and Banxi Sb-(Au-W) deposits may have precipitated from a less acidic ore-forming fluid and supports the idea of fluid mixing. More importantly, the relatively high contents of Rb, Ge, and Ti in quartz from the Woxi and Banxi Sb-(Au-W) deposits, combined with the low Al and Sr contents, imply that magmatic-hydrothermal systems possibly contributed to the ore-forming fluids. Based on the trace element compositions of quartz, two major types of Sb deposits were identified in the Xiangzhong metallogenic province: the giant Xikuangshan epithermal deposit in which the ore-forming fluids are relatively acidic, stable and have experienced water–rock reaction, generally similar to the Qinglong Sb deposit in the Youjiang metallogenic province. The second type is the orogenic-type deposit represented by the Woxi Sb-Au-W deposit, including the Banxi Sb deposit, where the ore-forming fluids have undergone fluid mixing and relatively weak water–rock reaction, and may have been joined by a small amount of magmatic-hydrothermal fluids. Together with the recently published Sb mineralization ages (149–144 Ma) of the Woxi Sb-Au-W deposit, it supports the idea that this type of Sb deposit is related to the Mesozoic magmatism. The Zhazixi Sb-W deposit shows transitional features between these two types of Sb deposits.

Specific features of gold ore formation
 in the southeastern Baikal-Patom metallogenic province (Dzhalagun ore field)

In the course of geological prospecting fulfilled with participation of the FGBI TsNIGRI within the Chayangro ore cluster of the Dodykhta-Uryakh ore region in the southeastern Baikal-Patom metallogenic province, the Dzhalagun lode gold prospect within the ore field of the same name was studied and its economic significance has been proved. It has been substantiated that the Dzhalagun gold prospect is closely similar to the typical gold ore deposits of the Bodaibo ore region in sense of the ore formation phasing, the character of the hydrothermal metasomatic processes, and the structure of the mineralized vein-veinlet zones. At the same time, a series of specific geological features of the Dzhalagun ore field and the prospect have been determined as to the structure and composition of the ore-hosting rocks, the intrusive magmatism, the hydrothermal metasomatic processes, and the mineral composition of the veinveinlet mineralization.

Constraints of C[sbnd]H[sbnd]O[sbnd]S[sbnd]Pb isotopes and fluid inclusions on the origin of the giant Zhugongtang carbonate-hosted Pb–Zn deposit in South China

The Sichuan–Yunnan–Guizhou (SYG) metallogenic province on the western margin of the Yangtze Block has long been a research focus and is an important region of Pb–Zn mineralization in China, but its genesis is poorly constrained. This study examines the Zhugongtang carbonate-hosted Pb–Zn deposit (>3.0 Mt, 0.09–35.04 wt% Pb + Zn), the largest discovery made in the past decade in the southeastern part of the SYG metallogenic province. Fluid inclusions from sphalerite and calcite, CHO–isotopes from calcite, and S–Pb isotopes from sulfide minerals in the Zhugongtang Pb–Zn deposit were analyzed to understand the sources and genesis of the metals and hydrothermal fluids. Fluid inclusions in sphalerite and calcite from the largest ore body indicate that the fluids of the main mineralization stage had low temperatures (105 °C–210 °C) and moderate salinities (0.35–12.89 wt% NaCl equiv.). The sulfides are characterized by narrow ranges of sulfur isotope compositions (δ34Spyrite = +14.27 ‰ to +15.89 ‰, δ34Ssphalerite = +14.31 ‰ to +15.53 ‰, and δ34Sgalena = +10.64 ‰ to +12.97 ‰), indicating that reduced sulfur was derived from sedimentary sulfate in the Devonian to Permian carbonate host rocks by thermochemical sulfate reduction with the addition of organic matter. The δ13CPDB and δ18OSMOW values of calcite range from − 8.6 ‰ to +0.82 ‰ and +15.45 ‰ to +19.41 ‰, respectively, which are similar to values for mantle, marine carbonate rocks, and sedimentary organic matter. The negative correlation between δ13CPDB and δ18OSMOW values indicates that CO2 in the hydrothermal fluids was sourced from marine carbonate rocks and sedimentary organic matter. Calculated δ18OH2O and δDH2O values range from +3.5 ‰ to +7.5 ‰, and −93 ‰ to −52 ‰, respectively, indicating that the ore-forming fluids were dominantly metamorphic, but diluted by meteoric water that had reacted with organic matter. The galena samples yield 206Pb/204Pb values of 18.52 to 18.82, 207Pb/204Pb of 15.68 to 15.93, and 208Pb/204Pb values of 38.97 to 39.96. The μ and ω values of the sulfides range from 9.61 to 10.07 and 38.84 to 43.67, respectively. These data plot on the upper crust Pb evolution curve, generally in the field of Devonian to lower Permian sedimentary rocks, although the value for one sample falls in the field of Proterozoic metamorphic rocks, pointing to a complex origin for the ore-forming materials. Overall, the fluid inclusion and isotope data, together with geological evidence, suggest that the ore-forming fluids of the Pb–Zn deposit were sourced from deep metamorphic water with the features of low temperatures and moderate salinities, and the ore-forming metals were sourced from Devonian to lower Permian sedimentary rocks and partly from basement rocks. The genesis of the Zhugongtang ore is typical of SYG-type deposits.

Neuro-Fuzzy-AHP (NFAHP) Technique for Copper Exploration Using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Geological Datasets in the Sahlabad Mining Area, East Iran

Fusion and analysis of thematic information layers using machine learning algorithms provide an important step toward achieving accurate mineral potential maps in the reconnaissance stage of mineral exploration. This study developed the Neuro-Fuzzy-AHP (NFAHP) technique for fusing remote sensing (i.e., ASTER alteration mineral image-maps) and geological datasets (i.e., lithological map, geochronological map, structural map, and geochemical map) to identify high potential zones of volcanic massive sulfide (VMS) copper mineralization in the Sahlabad mining area, east Iran. Argillic, phyllic, propylitic and gossan alteration zones were identified in the study area using band ratio and Selective Principal Components Analysis (SPCA) methods implemented to ASTER VNIR and SWIR bands. For each of the copper deposits, old mines and mineralization indices in the study area, information related to exploration factors such as ore mineralization, host-rock lithology, alterations, geochronological, geochemistry, and distance from high intensity lineament factor communities were investigated. Subsequently, the predictive power of these factors in identifying copper occurrences was evaluated using Back Propagation Neural Network (BPNN) technique. The BPNN results demonstrated that using the exploration factors, copper mineralizations in Sahlabad mining area could be identified with high accuracy. Lastly, using the Fuzzy-Analytic Hierarchy Process (Fuzzy-AHP) method, information layers were weighted and fused. As a result, a potential map of copper mineralization was generated, which pinpointed several high potential zones in the study area. For verification of the results, the documented copper deposits, old mines, and mineralization indices in the study area were plotted on the potential map, which is particularly appearing in high favorability parts of the potential map. In conclusion, the Neuro-Fuzzy-AHP (NFAHP) technique shows great reliability for copper exploration in the Sahlabad mining area, and it can be extrapolated to other metallogenic provinces in Iran and other regions for the reconnaissance stage of mineral exploration.

Mонгол орны зарим алтны ордуудын хүдэржилт, гарал үүслийн харьцуулалт

The gold mineralization of Mongolia has been described by many geologists. Mongolian gold deposits and occurrences can be divided into 23 metallogenic belts. It shows that Mongolia has a very high potential in gold production. Epigenetic gold deposits and occurrences in Mongolia are genetically classified into several types: Au-Ag epithermal vein, orogenic, intrusion related, skarn, and porphyry, iron oxide-copper-gold deposit types. Mongolian orogenic deposits are structurally controlled and related to shear zones or folds, and are mostly hosted in granitoids or metasedimentary rocks, and metamorphic rocks. These Au deposits commonly occur as massive auriferous quartz veins that contain sulfides and less commonly occur as disseminated and stockwork. In this paper, the geological characteristics, sulfur isotopic geochemistry, and geochemical data of ore-forming fluids of five gold lode deposits in Mongolia such as Tavt deposit located in the Eg river-Dhzida metallogenic belt of the Eg-Dzhida metallogenic province, Gatsuurt, Harganat, Ereen, Biluut, Sujigtei, Ulaanbulag deposits of the Dzuunmod ore district located in the North Khentii metallogenic belt of the Khangai- Khentii metallogenic province, and Olon Ovoot group gold deposits located in the Ulziit metallogenic belt and Undurnaran deposit located n the Kharmagtai-Khunguut-Oyut Ulaan metallogenic belt of the South Mongolian metallogenic province, and Chandman Uul deposit in the of South Kherlen-Buyant metallogenic belt of the Central-Eastern Mongolia metallogenic province are comprehensively compared. The features of gold ore mineralization, fluid inclusion, and S isotope of gold deposits are summarized and analyzed.

Mineralogical and Geochemical Characteristics of Carbonates and Their Geological Significance to the Fuli Pb-Zn Deposit, Yunnan Province

Mississippi Valley-Type (MVT) deposits are among the main types of Pb-Zn deposits that feature carbonate minerals as the main gangue minerals; their formation runs through the entire metallogenic process of MVT deposits. Therefore, carbonate minerals contain rich information on metallogenic fluid evolution and are thus important prospecting indicators. The Fuli Pb-Zn deposit in eastern Yunnan is located in the southeast of the Sichuan-Yunnan-Guizhou (SYG) Pb-Zn metallogenic province, which is the biggest producer of zinc and lead in China and contains more than 400 deposits and over 20 million tons of Pb + Zn reserves. The ore occurs in the interlayer fracture zone of Middle Permian Yangxin Formation Dolomite, and the orebody shape is generally stratiform. The main metal-bearing minerals of this deposit are sphalerite, galena, and pyrite; the gangue minerals mainly comprise dolomite and calcite. Three mineralized stages are observed (the early metallogenic period, the main metallogenic period, and the late metallogenic period) according to the characteristics of stratigraphic output, the intercalated contact relationship of gangue minerals, and the alteration characteristics of the wall rock. To determine the source and properties of the ore-forming fluid and the ore-forming process of the Fuli Pb-Zn deposit, different stages of mineralogy and trace element geochemical characteristics of hydrothermal dolomite were systematically studied. The minerals were observed under microscope and subjected to in situ analysis by LA-ICP-MS and C–O isotope test. The δ18OSMOW value of the dolomite in the metallogenic period was between 13.29‰ and 20.55‰, and the δ13CPDB value was between −4.13‰ and 3.5‰. Dolomite of the metallogenic period mainly came from the dissolution of carbonate wall rocks, while C in the ore-forming fluid came from the wall rocks. A few dolomites showed a trend of depleting δ13CPDB and δ18OSMOW at the same time, implying the influence of sedimentary rock contamination in the mantle multiphase system. The lower δ18O was due to the exchange of O isotopes between the wall rocks and the depleted δ18O in ore-forming fluids. From the early to the later stage of mineralization, the ore-forming fluid changed from alkaline to neutral to weakly acidic due to a decrease in the oxygen fugacity and temperature of the fluid; this change resulted in the precipitation of sulfide and dolomite in the deposit. From the early to the late stages of mineralization, Fe and Mn showed a downward trend. Fe and Mn entered the alkaline environment of the carbonate minerals, while Fe and Mn were released into the acidic fluid, indicating that due to the metasomatism from strong to weak, their metallogenic environment evolved from alkaline to acidic. From the early to the late stage of mineralization, Sr showed an upward trend, which might indicate that the continuous reaction between the hydrothermal fluid and the wall rock continuously released Sr into the fluid. The Fe-Sr and Mn-Sr diagrams show that two kinds of fluid mixing occurred in the ore-forming process. The Fuli Pb-Zn deposit may have formed from mineral precipitation caused by the mixing of the metal-rich, oxidized acidic fluid and the sulfur-rich, reduced alkaline fluid. The results show that the Fuli Pb-Zn deposit belongs to MVT deposits.

Trace element compositions of galena in an MVT deposit from the Sichuan-Yunnan-Guizhou metallogenic province, SW China: Constraints from LA-ICP-MS spot analysis and elemental mapping

Galena trace element signatures and element partitioning between associated sulfides are poorly constrained, especially in Mississippi Valley-type (MVT) Zn-Pb deposits. This study reports laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) spot analysis data of different stages of galena as well as elemental mapping results of typical sulfide assemblages in the Daliangzi Zn-Pb deposit, one of the largest MVT deposits in the Sichuan-Yunnan-Guizhou (SYG) metallogenic province, SW China. The galena is generally enriched in Sb and Ag, with minor Cd, Cu, and As, but depleted in Bi. Antimony was generally incorporated into galena lattice via Sb3+ + Ag+ ↔ 2Pb2+, and the substitution of 2Sb3+ + □ (vacancy) ↔ 3Pb2+ also occurred at high Sb content level (>1200 ppm). Direct substitution is the main way for Cd incorporation, while Cu and As may exist via coupled substitution. Micro-inclusions also play important roles in the incorporation of Sb, As, and Cu in some cases. The elemental distribution maps show that Sb, Ag, and Tl are dominantly incorporated into galena, while Cd, Fe, Mn, Cu, As, Ga, and Ge are primarily concentrated in sphalerite. However, when present tennantite-tetrahedrite will become the preferential host phase of Sb, Ag, Cu, and As. This elemental partitioning verifies that the preferential host sulfide for trace elements is controlled by intrinsic factors (e.g., oxidation state and ion radius) rather than external factors (e.g., metal sources, pressure, temperature, and redox conditions). External factors, such as temperature, may be vital for the partitioning of a given element (e.g., Cd) between priority and subordinate hosts. Additionally, the galena trace element characteristics are found to vary significantly with the ore genetic types, which appears to imply the applicability of galena geochemistry in the ore type discrimination.

A reconnaissance study of potentially important scandium deposits associated with carbonatite and alkaline igneous complexes of the Permian Emeishan Large Igneous Province, SW China

• The ELIP in SW China has a component of carbonatite-alkaline complexes that were not previously well known. • Pyroxenites of these complexes are composed of clinopyroxene with high Sc contents and can form low grade but high tonnage of Sc ores. • Exploration Targets for Sc in pyroxenites in three representative complexes have ∼12,000 to ∼36,000 tonnes of Sc metal at grades of ∼30 to ∼70 ppm. • Carbonatite-alkaline complexes of the ELIP may become a potentially important Sc metallogenic province and may be targets for exploration of REEs . Economically viable Sc deposits in the world are scarce and new and alternative resources are now urgently needed to ensure future sustainable supplies. We report here an essentially unknown, yet potentially important, type of Sc deposit that is associated with carbonatite and alkaline igneous complexes of the Permian Emeishan Large Igneous Province (ELIP), SW China. The ELIP is well known for its variably mineralized intrusions and flood basalts. Associated alkaline igneous complexes are minor in volume but important as possible sources of Sc and other REEs. Several such complexes occur in the N-S-trending Kangdian belt, where they are typically composed of pyroxenite, gabbro, and nepheline syenite. Some complexes also contain jacupirangite, melteigite, ijolite, and urtite. We show that some of these complexes contain carbonatites. The alkaline mafic-ultramafic rocks typically belong to either sodic or potassic magmatic series with high alkali compositions (up to 15.4 wt% Na 2 O + K 2 O). Pyroxenites in these complexes are composed of clinopyroxene with variable amounts of apatite and magnetite and have 39 to 71 ppm Sc. The Sc concentrations of these rocks may be high enough to justify mining under the current prices of Sc, which is nearly 5 times that of gold. Our preliminary study indicates a minimum of ∼12,000 to ∼36,000 tonnes of Sc metal in three representative complexes. This type of mineralization may ultimately contribute to a reliable and sustainable Sc supply chain in the future. In addition to Sc in the pyroxenites, carbonatites in these complexes will also be potentially important targets for REE exploration.

Upper crustal structure beneath the Qin-Hang and Wuyishan metallogenic belts in Southeast China as revealed by a joint active and passive seismic experiment

SUMMARY Southeast China is one of the most important polymetallic metallogenic provinces in the world. However, distinct differences in the type and origin of the mineral deposits are present between the major metallogenic belts in this province. To deepen our knowledge of this regional metallogenic setting, investigate the factors controlling its metallogenic differences and explore the feasibility of active and passive seismic imaging, we performed a multibatch seismic experiment using active and passive sources with the help of 437 short-period seismographs deployed across the Qin-Hang and Wuyishan metallogenic belts in Southeast China. We resolved the S-wave velocity structure beneath the profile using ambient noise tomography and derived a Vp/Vs model by combining with a published P-wave model. A good correlation between the obtained seismic velocity models and geological observations is observed. The Proterozoic volcanic-sedimentary rock series and the Fuzhou-Yongfeng sedimentary basin are identified by low P- and S-wave velocities, high Vp/Vs ratios and low S-wave velocity perturbations. Within the core of the Wuyishan Metallogenic Belt, several narrow, elongated and low seismic velocity anomalies are considered to be signs of the nearby fault zones, and these anomalies provide reference information on the extension and pattern of these faults at depth. Combined with the geological and mineralogical evidence, we propose that theses faults function as ore-guiding structures and facilitate the formation of regionally representative mineral species and metal assemblages.

Metallogeny of Manto-type stratabound Cu-(Ag) mineralization in Iran: Relationship with NeoTethyan evolution and implications for future exploration

Stratabound or “Manto-type/volcanic red-bed” Cu-(Ag) deposits occur along the Urumieh-Dokhtar magmatic arc (UDMA), Sanandaj-Sirjan Zone (SSZ), Alborz Magmatic Assemblage (AMA), Sabzevar Zone, and Lut Block structural zones of Iran, and are hosted by Cretaceous and Eocene volcanic and volcano-sedimentary rocks. The most important deposits of this type are East Narbaghi, Khankishi, Kahak, Veshnaveh, and Koshkouieh in the UDMA; Keshtmahaki in the SSZ; Mari, Qeblebolagh, and Yamaghan in the AMA; Abbasabad, Dochileh, Gol-Cheshmeh, Zangaloo, Abri, Rahbari, and Cheshmeh-Marzieh in the Sabzevar Zone; and Vorezg in the Lut Block. Back-arc extensional basins are the principal tectonic setting for the Manto-type deposits of Iran, that developed during the subduction of the NeoTethyan crust beneath the Iranian micro-continental plates. The stratigraphic sequences of these deposits are commonly formed from volcanics, volcaniclastics, and sedimentary rocks, which are similar to other volcanic-hosted stratabound copper districts around the world. Iranian Manto-type deposits are stratigraphically controlled in which Cu-(Ag) mineralization occurs as vein-veinlets, disseminated grains, and filling vesicles. Copper mineralization is commonly closely related to framboidal pyrite and pyrobitumen. The mineralogy of the Cu-(Ag) mineralization in all Manto-type deposits of Iran is simple and consists of chalcocite, bornite, native copper, chalcopyrite, acanthite, and minor secondary digenite, covellite, cuprite, tenorite, chrysocolla, anilite, malachite, azurite, and Ag-bearing clausthalite as the main economic minerals, accompanied by pyrite, chlorite, calcite, quartz, and zeolite. Copper sulfides occur mainly as a replacement of diagenetic pyrite, which in turn, replaced pyrobitumen. Iranian Manto-type deposits are interpreted to be the result of mineralizing hydrothermal fluids derived from footwall volcanic rocks that migrated upwards, driven by the late diagenetic processes. The UDMA and Sabzevar Zone are the most favorable metallogenic provinces in Iran for Manto-type Cu-(Ag) exploration since these two zones host the largest copper deposits of this type, including Abbasabad, Koshkouieh, East Narbaghi, and Abri deposits. Consequently, reconstruction of orebearing basins, such as presented, is not only critical to understanding the genesis of ancient deposits and their tectonic setting, but also for guiding exploration in deposit-proximal areas.

Fluid evolution and ore genesis of Cu–Pb–Zn veins in the Panjiaduan deposit, Great Xing’an Range, NE China: evidence from fluid inclusion and H–O–He–Ar isotopes

AbstractThe southern Great Xing’an Range (SGXR), located in the eastern segment of the Central Asian Orogenic Belt (CAOB), is one of the most economically important Cu–Mo–Fe–Sn–Pb–Zn–Ag metallogenic provinces in China. The newly discovered Panjiaduan Cu–Pb–Zn deposit (9.3 Mt; at 1.36% Cu, 2.90% Pb, 3.80% Zn and 38.12 g/t Ag), located in the SE segment of the SGXR, is primarily hosted in fracture zones in volcanic rocks and granodiorite of the Manitu Formation. Four paragenetic stages of metallic mineralization are identified: (I) quartz-pyrite-arsenopyrite; (II) quartz-polymetallic sulphide; (III) quartz-galena-sphalerite-argentite; and (IV) quartz-calcite-minor sulphide. The hydrothermal quartz contains three types of primary fluid inclusion (FIs): vapour-rich two-phase liquid-vapour (LV-type), liquid-rich two-phase liquid-vapour (VL-type) and three-phase liquid-vapour-solid FIs (SL-type). Stages I and II contain all types with homogenization temperatures (Th) of 324–386 °C and 276–334 °C as well as salinities of 0.7–38.0 wt% and 0.9–34.7 wt%, respectively, whereas stage III is composed of VL- and LV-type FIs with Th of 210–269 °C and salinities of 0.5–7.2 wt%. Only VL-type FIs occur in stage IV, with Th of 139–185 °C and salinities of 1.6–4.2 wt%. The δ18OH2O and δD values vary from −15.7 to 2.6‰ and −132.7 to −110.2‰, respectively, indicating predominant meteoric water with an initial magmatic source. The He–Ar isotopic compositions of the pyrite inclusions from the Panjiaduan Cu–Pb–Zn veins suggest that fluids were derived from the crust.

A Historical Overview of Conceptual Approaches in Mineral Exploration with Special Reference to Uranium Exploration in India

Abstract Minerals and metals find mentioned in India’s ‘Shruthies’ (Vedic) and ‘Smruthies’ (Ithihasas and Puranas) but the exploration concepts had remained latent. After a huge hiatus, the Industrial Revolution of the mid-18th century can be said to have heralded the need to seek mineral resources world-wide. Ancient mining activities were the obvious precursors used by the prospectors to seek new mineral resources. The ‘Spatial and Temporal’ association of the ‘metallogenic provinces’ thus also became clearer. The ‘mineral system concept’ came up since 1990s and are being used for seeking new Mississipi Valley Type, Pb-Zn-Cu and SEDAX type deposits along passive, continental margins. The ‘Common Earth Model’ came up in the new millenia for petroleum exploration with inferences on the depth aspects petroleum basins. Such a fusion of concepts and advanced exploration techniques have helped in the preparation of ‘prospectivity maps’ for seeking ‘green field terrains’ to discover new mineral resource bases. The second world-war which demonstrated the fission-power of uranium ushered in the race for atomic minerals, especially uranium, throughout the world including India. Crustal evolution and the time-bound character of specific uranium deposit-types marked a major shift in uranium exploration concepts world-wide including India. Metamorphic, vein type deposits of Singhbhum, Jharkhand (Jaduguda, Narwapaharh, Turamdih and others explored since the early 1950s), the sandstone types at Domiasiat and Wakhyn in Meghalaya, the albitite-hosted uranium at Rohil, Rajasthan and the unique, low-grade, large tonnage, carbonate-hosted Tummallapalle group of deposits in Andhra Pradesh discovered and proved since the late 1970s, form the main resource base of uranium in India.

Role of fractional crystallization, fluid-melt separation, and alteration on the Li and B isotopic composition of a highly evolved composite granite pluton: The case of the Eibenstock granite, Erzgebirge, Germany

We present a comprehensive Li and B isotope study of granites, aplites, and igneous enclaves from the multi-phase Eibenstock granite in the Western Erzgebirge-Vogtland metallogenic province of Germany. The studied samples cover the entire compositional range of the granites from moderately to highly evolved and include variably altered types as obtained by magmatic fractionation, post-magmatic high- to medium-temperature and near-surface low-temperature alteration. Fractionation and alteration processes are unequivocally documented by the chemical variability of the rocks. Despite the marked imprint of these processes on bulk-rock compositions, our granite samples show only little variation in δ 7 Li (−0.52 to 0.75‰) and δ 11 B (−17.46 to −14.78‰), with surface samples defining the lower end of the δ 7 Li range. The narrow range in δ 7 Li suggests that magmatic fractionation and high-temperature overprint have a very minor effect on δ 7 Li. The B budget of the samples is dominated by tourmaline, which makes δ 11 B values insensitive for later high- to medium-temperature overprint or surficial low-temperature alteration. Depending on whether tourmaline crystallized before or after exsolution and loss of magmatic fluids, whole-rock samples have higher or lower δ 11 B values. Granite enclaves have δ 7 Li and δ 11 B values ranging from −1.51 to −0.81‰ and − 14.55 to −13.89‰, respectively. Some samples have chemical and mineralogical evidence for wall-rock interaction during emplacement or later overprint by external fluids. These samples show broader ranges in δ 7 Li (−2.61 to 2.21‰) and δ 11 B (−21.58 to −9.85‰). These values show that wall-rock interaction via assimilation and external fluids may affect δ 7 Li and δ 11 B to a larger extent than intra-magmatic processes, such as fractional crystallization, fluid-mediated autometasomatic overprinting, or exsolution of fluids from the melt. The offset of δ 7 Li and δ 11 B values towards the compositions of the wall rocks reflects the contrasting composition of granite and country rock and the addition of country-rock material to the granite. The magnitude of the offset reflects both the relative contribution of wall-rock derived Li and B to the granite and the magnitude of the difference in the Li and B isotopic compositions between them. • Whole rock δ 7 Li and δ 11 B are essentially unaffected by magmatic fractionation. • Fluid-melt separation may reduce δ 7 Li and δ 11 B in residual melt. • Effect of intra-granitic alteration on δ 7 Li and δ 11 B of granitic rocks is small. • Effects on δ 7 Li and δ 11 B during alteration depend on fluid source.

A 3D Predictive Method for Deep-Seated Gold Deposits in the Northwest Jiaodong Peninsula and Predicted Results of Main Metallogenic Belts

With the rapid depletion of mineral resources, deep prospecting is becoming a frontier field in international geological exploration. The prediction of deep mineral resources is the premise and foundation of deep prospecting. However, conventional metallogenic predictive methods, which are mainly based on surface geophysical, geochemical, and remote sensing data and geological information, are no longer suitable for deep metallogenic prediction due to the large burial depth of deep-seated deposits. Consequently, 3D metallogenic prediction becomes a critical method for delineating deep prospecting target areas. As a world-class giant gold metallogenic province, the Jiaodong Peninsula is at the forefront in China in terms of deep prospecting achievements and exploration depth. Therefore, it has unique conditions for 3D metallogenic prediction and plays an important exemplary role in promoting the development of global deep prospecting. This study briefly introduced the method, bases, and results of the 3D metallogenic prediction in the northwest Jiaodong Peninsula and then established 3D geological models of gold concentration areas in the northwest Jiaodong Peninsula using drilling combined with geophysics. Since gold deposits in the northwest Jiaodong Peninsula are often controlled by faulting in the 3D space, this study proposed a method for predicting deep prospecting target areas based on a stepped metallogenic model and a method for predicting the deep resource potential of gold deposits based on the shallow resources of ore-controlling faults. Multiple characteristic variables were extracted from the 3D geological models of the gold concentration areas, including the buffer zone and dip angle of faults, the changing rate of fault dip angle, and the equidistant distribution of orebodies. Using these characteristic variables, five deep prospecting target areas in the Jiaojia and Sanshandao faults were predicted. Moreover, based on the proven gold resources at an elevation of −2000 m and above, the total gold resources of the Sanshandao, Jiaojia, and Zhaoping ore-controlling faults at an elevation of −5000–−2000 m were predicted to be approximately 3377–6490 t of Au. Therefore, it is believed that the total gold resources in the Jiaodong Peninsula are expected to exceed 10,000 t. These new predicted results suggest that the northwest Jiaodong Peninsula has huge potential for the resources of deep gold deposits, laying the foundation for further deep prospecting.

Petrogenesis and Tectonic Implications of the Ore-Associated Intrusions in Bayanbaolege Ag Polymetallic Deposit, Inner Mongolia, NE China

The large Bayanbaolege Ag polymetallic ore deposit is located in the Tuquan-Linxi Fe (Sn)-Cu-Pb-Zn-Ag-Nb (Ta) polymetallic metallogenic belt, which is an important part of the Great Xing’an Range metallogenic province, northeast China. The sulfide–quartz vein-type orebodies in the deposit are mainly hosted in the Cretaceous granodiorite porphyry and Late Permian Linxi formation. The U-Pb dating of the zircon from the post-ore diorite porphyrite yields an age of 124.8 ± 1.1 Ma, which constrains the mineralization time at the Early Cretaceous. The Sr-Nd isotope values (87Sr/86Sr)i = 0.708576~0.710536; εNd (t) = −0.51~+0.69; the Hf isotope values 176Hf/177Hf = 0.2827278~0.2830095, the εHf (t) = +3.1~+11.2, TDM2 = 615~1341 Ma of the metallogenic granodiorite porphyry. The Hf isotope values 176Hf/177Hf = 0.2828596~0.2829451, and the εHf (t) = +5.7~+8.8 of the diorite porphyrite, TDM2 = 827~1108 Ma, indicating that the ore-forming materials were the possible involvement of heterogeneous juvenile sources including moderately depleted mantle and newly underplated lower crust. The major and trace elements (including REEs) implied that these intrusions are the I-type granite and linked intimately to the westward subduction of the Paleo-Pacific Ocean plate. From these whole-rock major and trace elements and zircon U-Pb ages, as well as Sr-Nd-Hf isotope data, we conclude that the ore-associated I-type granites in the Bayanbaolege deposit formed in an extensional tectonic setting of the Early Cretaceous, and are compactly related to the retreat of the Paleo-Pacific Ocean subducted plate linked intimately to the westward subduction of the Paleo-Pacific Ocean plate rather than the closure of the Mongol–Okhotsk Ocean. Furthermore, by integrating geological background work and previous research work, implying the mineralization age of the Bayanbaolege deposit should have been formed in the 125–130 Ma.

The effects of red beds on fluid flow and implications for the formation of volcanic-type uranium deposits in the Xiangshan basin, China

The South China uranium metallogenic province is an important hydrothermal uranium metallogenic region in China, which is spatially and temporally associated with the Cretaceous-Neogene red beds. Previous studies suggest that the red beds might have played critical role in the ore-forming processes by providing oxidizing fluids. However, the effects of the red beds on fluid flow are poorly understood. In this study, numerical modeling was conducted to investigate the roles of red beds on ore-forming fluid flow in the Xiangshan basin in Jiangxi Province, hosting the largest volcanic hydrothermal uranium deposit in China. The modeling results show that the variation of the slope gradient of the red beds greatly affects the fluid flow patterns, whereas the change of thickness and permeability of the red beds has little influence on fluid flow pattern. The fluid can circulate into the volcanic and basement rocks driven by topographic relief of the red beds. Furthermore, for models with fault, although the fluid velocities in the fault were more than one order of magnitude larger than those in the surrounding strata, the overall fluid flow patterns in the strata did not show great variation. The modelling results suggest that the topographic relief of the red beds may have driven the oxidizing fluids into the underlying rocks which are necessary for uranium mineralization in the Xiangshan basin.

Polymetallic mineralization prospectivity modelling using multi-geospatial data in logistic regression: The Diapiric Zone, Northeastern Algeria

Prospecting and exploring minerals present major challenges in tectonically complex regions for sustainable development as in Northeastern Algeria. This area is promising for its mineral potential, especially the metallogenic province ‘The Diapiric Zone’. This study concerns mapping and predicting potential polymetallic mineralization locations by integration of remote sensing, gravity, and magnetic datasets. Several enhancement and processing methods have been applied on Landsat8_OLI and ASTER_1T remote sensed data to reduce uncertainty for achieving the best detection of hydrothermal alteration zones and lithological mapping. Furthermore, the Centre for Exploration Targeting grid analysis technique, the contact occurrence density and entropy orientation tools were employed on ground-gravity and aeromagnetic data to understand and visualize the pathways for hydrothermal fluids circulation of mineral deposits. The polymetallic mineralization prospective areas were produced using a logistic regression model on the resulting multifactor. High zones of lead-zinc cover most the area that has been confirmed by field investigation.

Mineralogy and Origin of the Manganese Deposit in the Sulaimani Province, Kurdistan Region of Iraq: Insight to Serpentinization-Induced Manganese Production Scenario

The Manganese deposits in Sulaimani metallogenic province mainly occur within the top Qulqula Radiolarite chert unit of the Penjween ophiolite complex as strata bound type deposits near Kani Saif village, 15 km south of the Penjween district within the Imbricated zone, Kurdistan Region of Iraq. A restricted occurrence of massive manganese boulders was identified, 1 km north to the Mawat District, associated with the Oligocene Merga Red beds Group. The Qulqula Radiolarite represents the Middle Jurassic-Early Cretaceous sedimentary cover of Neo-Tethys oceanic crust deposits throughout the early to mature stages of the Neo-Tethys ocean opening along the northern and eastern margins of the Afro-Arabian plate. The field and petrographical data indicated that the nature of manganese mineralization in the area is of various forms including veins, brecciated, micronodules, banded and massive types. Reflected light microscopy, high resolution scanning electron microscope and X-ray diffraction reveal that the mineral assemblages are dominated by barunite, rhodinite, hematite, quartz and carbonate for the massive metamorphosed type deposit in the Mawat area. Meanwhile, the mineralogy of the vein, micronodule and banded types are simple and dominated by pyrolusite, hollandite minerals close to Kain Saif village. Combinations of the modal manganese minerals, filed and textural observations, a paragenetic-time model suggests that the manganese deposit in the area formed via a sequence of multiple processes (1) serpentinization of the upper mantle at mid oceanic ridge during the Cretaceous period, (2) deposition from diluted hydrothermal fluids in the Neo-Tethys mature oceanic basin, (3) the diagenetic modification of the manganese bearing sediment and (4) metamorphism of sediment a combing Zagros orogeny in Paleogene. Overall data suggest that the manganese deposits in the Kurdistan region of Iraq are cogenetic and spatially related to those which occur along the entire margin of the Arabian plates from Oman to Turkey associated with the radiolarite facies.