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18 pages, 11767 KiB

Open AccessFeature PaperArticle

Aeschynite Group Minerals Are a Potential Recovery Target for Niobium Resources at the Giant Bayan Obo Nb–REE–Fe Deposit in China

by Bo Yang, Li Yang, Yong-Gang Zhao, Guo-Ying Yan, Jian-Yong Liu, Wen-Xiang Meng, Jun-Fang Yu, Lei Chen, Xiao-Chun Li and Xian-Hua Li

Minerals 2024, 14(10), 1029; https://doi.org/10.3390/min14101029 - 14 Oct 2024

Viewed by 818

Abstract

With the development of the steel industry, China’s demand for niobium is increasing. However, domestic niobium resources are not yet stably supplied and are heavily dependent on imports from abroad (nearly 100%). It is urgent to develop domestic niobium resources. The Bayan Obo [...] Read more.

With the development of the steel industry, China’s demand for niobium is increasing. However, domestic niobium resources are not yet stably supplied and are heavily dependent on imports from abroad (nearly 100%). It is urgent to develop domestic niobium resources. The Bayan Obo deposit is the largest rare earth element deposit in the world and contains a huge amount of niobium resources. However, the niobium resource has not been exploited due to the fine-grained size and heterogeneous and scattered occurrences of Nb minerals. To promote the utilization of niobium resources in the Bayan Obo deposit, we focused on the mineralogical and geochemical characterization of six types of ores and mineral processing samples from the Bayan Obo deposit, using optical microscopes, EPMA, TIMA, and LA–ICP–MS. Our results show that: (1) the niobium mineral compositions are complex, with the main Nb minerals including aeschynite group minerals, columbite–(Fe), fluorcalciopyrochlore, Nb–bearing rutile, baotite, fergusonite–(Y), fersmite, and a small amount of samarskite–(Y). Aeschynite group minerals, columbite–(Fe), and fluorcalciopyrochlore are the main niobium-carrying minerals and should be the primary focus of industrial recycling and utilization. Based on mineralogical and geochemical investigation, the size of the aeschynite group minerals is large enough for mineral processing. Aeschynite group minerals are thus a significant potential recovery target for niobium, as well as for medium–heavy REE resources. The Nb–rich aegirine-type ores with aeschynite group mineral megacrysts are suggested to be the most significant niobium resource for mineral processing and prospecting. Combined with geological features, mining, and mineral processing, niobium beneficiation efforts of aeschynite group minerals are crucial for making breakthroughs in the utilization of niobium resources at the Bayan Obo. Full article

(This article belongs to the Special Issue Mineral Resources in North China Craton)

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21 pages, 6293 KiB

Open AccessArticle

The Formation Age and Magma Source of the Xiaonanshan–Tunaobao Cu-Ni-PGE Deposit in the Northern Margin of the North China Craton

by Guanlin Bai, Jiangang Jiao, Xiaotong Zheng, Yunfei Ma and Chao Gao

Minerals 2024, 14(7), 733; https://doi.org/10.3390/min14070733 - 22 Jul 2024

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Abstract

The Xiaonanshan–Tunaobao Cu-Ni-PGE deposit is located in the northern margin of the North China Craton (N-NCC) in central Inner Mongolia. However, the age, magma source, petrogenesis, and sulfide mineralization mechanism of the ore-related Xiaonanshan-Tunaobao pluton remain unclear. Zircon U-Pb dating indicates the Tunaobao [...] Read more.

The Xiaonanshan–Tunaobao Cu-Ni-PGE deposit is located in the northern margin of the North China Craton (N-NCC) in central Inner Mongolia. However, the age, magma source, petrogenesis, and sulfide mineralization mechanism of the ore-related Xiaonanshan-Tunaobao pluton remain unclear. Zircon U-Pb dating indicates the Tunaobao pluton formed at 275.9 ± 2.8 Ma (Early Permian), similar to the Xiaonanshan pluton (272.7 ± 2.9 Ma). The ore-related gabbro is enriched in LREE and LILE (e.g., Rb) and depleted in HREE and HFSE (e.g., Nb and Ti). It likely originated from enriched mantle metasomatized by subduction fluids, supported by enriched Hf-Nd isotopes (–34.34 to –6.16 for zircon ε_Hf(t) and –7.24 to –5.92 for whole-rock ε_Nd(t) values) and high Ba/La but low Rb/Y ratios. The δ³⁴S values of the Xiaonanshan sulfides range from 4.5‰ to 11.4‰, indicating a mantle origin with contribution from surrounding rocks. Combining previous recognition with this study, we propose that the Xiaonanshan–Tunaobao pluton formed in a post-collision extensional setting. Full article

(This article belongs to the Special Issue Mineral Resources in North China Craton)

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31 pages, 31932 KiB

Open AccessArticle

The Zircon U-Pb Age, Hf Isotopes, and Lithogeochemistry of Ore-Bearing Rocks from the Archean Hongtoushan Volcanogenic Massive Sulfide Deposit in the North China Craton: Implications for Tectonic Setting

by Xinwei You, Ende Wang, Yekai Men, Jianfei Fu, Kun Song and Sishun Ma

Minerals 2024, 14(4), 367; https://doi.org/10.3390/min14040367 - 29 Mar 2024

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Abstract

Volcanogenic massive sulfide (VMS) deposits are globally significant sources of metals. The Hongtoushan VMS deposit is the only large Archean Cu-Zn VMS deposit in the North China Craton, carrying substantial economic value. Significant deformation and metamorphism have made the tectonic setting of the [...] Read more.

Volcanogenic massive sulfide (VMS) deposits are globally significant sources of metals. The Hongtoushan VMS deposit is the only large Archean Cu-Zn VMS deposit in the North China Craton, carrying substantial economic value. Significant deformation and metamorphism have made the tectonic setting of the Hongtoushan VMS deposit the subject of extensive debate. This study investigates the petrogenesis and chronology of the ore-bearing host rocks from the Hongtoushan Cu-Zn VMS deposit in the North China Craton. By utilizing whole-rock geochemical analyses and zircon dating, this research sheds light on the origin and evolution of the ore-bearing rocks within the deposit. The whole-rock geochemical analysis data indicate that the Hongtoushan ore-bearing rock series is mainly composed of amphibole plagioclase gneiss (basalt protolith) and biotite plagioclase gneiss (andesite and rhyolite protolith), suggesting a complete volcanic cycle from basic to medium-acidic volcanic rocks. The amphibole plagioclase gneiss has slight LREE enrichment patterns with unremarkable depletions of Nb, Ta, and Ti and belongs to contaminated ocean plateau basalt (OPB) in terms of composition, which is generally interpreted as being generated from the mantle plume head. Meanwhile, the biotite plagioclase gneiss has relatively steep LREE enrichment distribution patterns with remarkable negative Ta, Nb, and Ti anomalies and a wide range of Zr/Y ratios, indicating their classification as FI- and FII-type felsic rocks; they were likely formed through the fractional crystallization of basic magma combined with crustal assimilation. When combined with the zircon dating results, the ore-bearing host rocks of the Hongtoushan VMS deposit were generated via a continuous magmatic evolution process. The zircon dating of the host rocks indicates a formation age of between 2609 and 2503 Ma, with metamorphic events between 2540 and 2466 Ma, which is consistent with the 2.5 Ga-related global mantle plume event. Further research shows that the ore-bearing host rocks are more likely to have been formed in a mantle plume-related stretching environment, possibly a margin rift. Full article

(This article belongs to the Special Issue Mineral Resources in North China Craton)

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25 pages, 79336 KiB

Open AccessArticle

Pyrite Textures and Compositions in the Dunbasitao Gold Deposit, NW China: Implications for Ore Genesis and Gold Mineralization Processes

by Wenxiang Liu, Xiaohua Deng, Shen Han, Xi Chen, Xun Li, Abulimiti Aibai, Yanshuang Wu, Yong Wang, Wei Shan, Zengsheng Li and Yanjing Chen

Minerals 2023, 13(4), 534; https://doi.org/10.3390/min13040534 - 11 Apr 2023

Cited by 3 | Viewed by 2420

Abstract

The process and mechanism of gold mineralization are frontier issues. The Dunbasitao deposit is the most important gold deposit discovered along the Armantai suture zone, East Junggar, NW China, which indicates the potential for future ore exploration in this area. Orebodies are mainly [...] Read more.

The process and mechanism of gold mineralization are frontier issues. The Dunbasitao deposit is the most important gold deposit discovered along the Armantai suture zone, East Junggar, NW China, which indicates the potential for future ore exploration in this area. Orebodies are mainly hosted in Lower Carboniferous Jiangbasitao Formation volcano-sedimentary rocks, and the ores are characterized by multistage pyrites. Based on microscopy and backscattered electron imaging studies, pyrites are classified into five types: the pre-ore framboidal/colloidal Py0; the early-stage coarse-grained, cubic, and homogeneous Py1; and the middle-stage fine-grained, cubic/pyritohedron Py2 that includes Py2a (core), Py2b (mantle), and Py2c (rim). The results of the EPMA and in situ LA-ICP-MS analyses show that trace elements of pyrite mainly occur in two forms: solid solutions and invisible or visible inclusions. Mn, Co, Ni, and As enter the pyrite lattice, whereas Ti occurs as mineral inclusions, and Au, Cu, Zn, Sb, and Pb can occur in both forms. Au and As show a positive linear relationship with r = 0.850. Py2b has much higher Au contents (20.1 to 201 ppm) than other pyrite types (Py0: 0.01 to 0.36 ppm; Py1: 0.01 to 0.02 ppm; Py2a: 0.31 to 2.48 ppm; and Py2c: 0.18 to 18.0 ppm). The Dunbasitao deposit is classified as an orogenic gold deposit using the two latest machine learning classifiers based on pyrite trace element data. Fluid immiscibility, sudden cooling, and the substitution of S¹⁻ with As¹⁻ might be crucial mechanisms leading to Au precipitation. Initial ore-forming fluids brought major amounts of As, Au, Co, Ni, Se, Zn, Ag, Cd, Sn, and other elements, and the Jiangbasitao Formation host rocks contributed a certain amount of As, Ni, Cu, Sb, Pb, and Bi, at least. Full article

(This article belongs to the Special Issue Mineral Resources in North China Craton)

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20 pages, 4099 KiB

Open AccessArticle

Evolution Characteristics through Thermo-Rheological Lithosphere of the Liaonan Metamorphic Core Complex, Eastern North China Craton

by Haonan Gan, Junlai Liu, Guiling Wang and Wei Zhang

Minerals 2022, 12(12), 1570; https://doi.org/10.3390/min12121570 - 6 Dec 2022

Cited by 1 | Viewed by 1514

Abstract

Metamorphic core complexes are developed in crustal activity belts at the continental margins or within continents, and their main tectonic feature is that the ductile middle crust is exhumed at the surface. The deformation properties are closely related to the geodynamic process affecting [...] Read more.

Metamorphic core complexes are developed in crustal activity belts at the continental margins or within continents, and their main tectonic feature is that the ductile middle crust is exhumed at the surface. The deformation properties are closely related to the geodynamic process affecting the continental crust. However, the evolution of the metamorphic core complexes after their formation is still unclear. The Cretaceous Liaonan metamorphic core complex developed in the eastern North China craton provides an ideal environment to study its evolution. In this study, we estimate the paleo-temperature and paleo-stress at the time of formation of the metamorphic core complex dynamical recrystallization of quartz and calculate the thermo-rheological structure of the present Liaonan metamorphic core complex by one-dimensional steady-state heat conduction equation and power-creep law. The results show that compared with the Cretaceous period, the geothermal heat flow value of the present Liaonan metamorphic core complex decreases from 70–80 mW/m² to 49.4 mW/m², the thermal lithosphere thickness increases from 59–75 km to 173 km, and the brittle transition depth increases from 10–13 km to about 70 km, showing coupling of the crust–mantle rheological structure. We speculate that the evolution of the thermo-rheological structure of the Liaonan metamorphic core complex is possibly caused by rapid heat loss or lithospheric mantle flow in the Bohai Bay Basin. Full article

(This article belongs to the Special Issue Mineral Resources in North China Craton)

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23 pages, 10389 KiB

Open AccessArticle

Mineral Chemistry of the Lower Cretaceous Jinling Iron Skarn Deposit, Western Shandong Province, North China Craton: Implications for the Iron Skarn Mineralization Process

by Fang-Hua Cui, Chao Zhang, Dai-Tian Jin, Lu-Yuan Wang, Ji-Lei Gao, Ming Ma and Ya-Dong Li

Minerals 2022, 12(9), 1152; https://doi.org/10.3390/min12091152 - 12 Sep 2022

Cited by 3 | Viewed by 2430

Abstract

The source of iron material and the mineralization process of iron skarn deposits within the eastern North China Craton are ambiguous. In this study, we present new mineral chemical data of the Jinling skarn deposit, located in western Shandong Province, east China. Based [...] Read more.

The source of iron material and the mineralization process of iron skarn deposits within the eastern North China Craton are ambiguous. In this study, we present new mineral chemical data of the Jinling skarn deposit, located in western Shandong Province, east China. Based on the petrography study and mineral chemical data, we suggest that the Jinling iron skarn deposit is hydrothermal and the metallogenic iron is enriched by leaching of Fe-rich fluids derived from primitive magmatic melt from the solidified diorites. The Jinling iron skarn deposit formed as a result of several mineralization processes: (1) Fe-rich hydrothermal fluids exsolved from a hydrous parental magma that was characterized by high iron content, oxygen fugacity (fO₂), and salinity; (2) the Fe content of the fluids was augmented during the alkali metasomatism stage via the leaching of Fe from the solidified dioritic rocks; (3) diopside and garnet in skarns formed under relatively alkaline and oxidizing conditions during the later prograde skarn stage; (4) during the retrograde skarn stage, amphibole, chlorite, epidote, phlogopite, serpentine, biotite, and chlorite formed under more oxidizing conditions, and subsequent mixing of the Fe-rich fluids with meteoric water triggered the precipitation of the massive magnetite; and (5) the final sulfide–carbonate stage was involved in the formation of carbonate and sulfide minerals as a result of a change in conditions from oxidizing to reducing. Full article

(This article belongs to the Special Issue Mineral Resources in North China Craton)

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19 pages, 7794 KiB

Open AccessArticle

Sericite ⁴⁰Ar/³⁹Ar Dating and Indosinian Mineralization in the Liushuping Au–Zn Deposit, West Qinling Orogen, China

by Suwei Yue, Xiaohua Deng, Xiaoxu Yan and Jianxiang Chen

Minerals 2022, 12(6), 666; https://doi.org/10.3390/min12060666 - 25 May 2022

Cited by 2 | Viewed by 1932

Abstract

The Liushuping deposit, located on the northeast margin of the Bikou Block, is the middle-sized gold-zinc deposit (with ore reserves of 15.67 × 10⁴ t Zn and 2.2 t Au) in the Mianxian–Lueyang–Yangpingguan area. The orebodies occur in the meta-dolomite of the [...] Read more.

The Liushuping deposit, located on the northeast margin of the Bikou Block, is the middle-sized gold-zinc deposit (with ore reserves of 15.67 × 10⁴ t Zn and 2.2 t Au) in the Mianxian–Lueyang–Yangpingguan area. The orebodies occur in the meta-dolomite of the Duantouya and Jiudaoguai formations controlled by the Jiudaoguai syncline. The ore-forming process has experienced hydrothermal period and epigenetic oxidation period, and the hydrothermal period can be divided into two stages. The hydrothermal sericite sample collected from stage 2 yielded a well-defined ⁴⁰Ar/³⁹Ar isotopic plateau age of 215.70 ± 0.37 Ma, and an ³⁹Ar/³⁶Ar-⁴⁰Ar/³⁶Ar normal isochron age of 215.35 ± 0.38 Ma, indicating that the metallogenic age of the Liushuping is the Late Triassic (ca. 215 Ma). The I_Sr(t) of sphalerite is higher than that of the Bikou Group but similar to the Duantouya Formation, indicating that the ore-forming fluids may mainly originate from the metamorphic dehydration of the Duantouya Formation. The Liushuping Au–Zn deposit is consistent with that of the Qinling Indosinian orogeny and mineralization, which are related to oceanic subduction during the Late Triassic. Full article

(This article belongs to the Special Issue Mineral Resources in North China Craton)

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16 pages, 4871 KiB

Open AccessArticle

Chemical Composition and Strontium Isotope Characteristics of Scheelite from the Doranasai Gold Deposit, NW China: Implications for Ore Genesis

by Xun Li, Abulimiti Aibai, Xiheng He, Rongzhen Tang and Yanjing Chen

Minerals 2022, 12(5), 637; https://doi.org/10.3390/min12050637 - 18 May 2022

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Abstract

Scheelite, as a common accessory mineral found in hydrothermal deposits, is an indicator that allows the study of the ore-forming hydrothermal process and the tracing of fluid sources. The Doranasai gold deposit is a large-sized orogenic gold deposit in the South Altai, and [...] Read more.

Scheelite, as a common accessory mineral found in hydrothermal deposits, is an indicator that allows the study of the ore-forming hydrothermal process and the tracing of fluid sources. The Doranasai gold deposit is a large-sized orogenic gold deposit in the South Altai, and orebodies occur as veins in the Devonian Tuokesalei Formation and Permian albite granite dykes. The ores are quartz veins and altered tectonites (rocks). Here, scheelite can be observed in the early-stage milky quartz veins, the middle-stage smoky quartz-polymetallic sulfide veins, and the altered albite granite dykes. In this study, the scheelites of these three types were carefully investigated in terms of texture, element, and isotope geochemistry to understand their ore-forming processes and fluid sources. The results showed that all types of scheelite were rich in Sr and poor in Mo, indicating that their ore-forming fluids had no genetic relation to magmatic–hydrothermal activities. The scheelites were characterized by the enrichment of medium rare earth element (MREE) and positive Eu anomaly in the chondrite-standardized REE patterns. This indicated the REE differentiation between scheelite and fluid, i.e., REE³⁺ and Na⁺ were in the form of valence compensation, preferentially replacing Ca²⁺ and selectively entering the scheelite lattice. The trace element composition of scheelite showed that the ore-forming fluid system was relatively closed, mesothermal, Na-rich, and reductive. The Sr isotope ratio of the scheelite (0.704819–0.70860, average 0.706372) was higher than that of the ore-bearing albite granite dyke (0.704654–0.704735), indicating that the Tuokesalei Formation is the main source for the fluids forming the Doranasai deposit. Full article

(This article belongs to the Special Issue Mineral Resources in North China Craton)

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