Next Article in Journal
Comparative Analysis of CO2 Sequestration Potential in Shale Reservoirs: Insights from the Longmaxi and Qiongzhusi Formations
Previous Article in Journal
Dry Concentration of Phosphate Ore by Using a Triboelectrostatic Belt Separator in Pilot Scale
Previous Article in Special Issue
Petrogenesis of Tholeiitic Basalts from CZK06 Drill Core on the Tianchi Volcano, China–North Korea Border
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Minerals
Volume 15
Issue 9
10.3390/min15090996
minerals-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Fe–Si–O Isotope Characteristics and Ore Formation Mechanisms of the Hugushan Area BIF-Type Iron Deposits in the Central North China Craton

by
Ende Wang
1,
Deqing Zhang
1,*,
Jinpeng Luan
1,2,
Yekai Men
3,
Ran Wang
4,
Jianming Xia
3 and
Suibo Zhang
5
1
Department of Geology, School of Resource and Civil Engineering, Northeastern University, Shenyang 110819, China
2
Liaoning Key Laboratory of Green Development of Mineral Resources, Fuxin 123000, China
3
School of Resource & Materials, Northeastern University at Qinhuangdao, Qinhuangdao 066004, China
4
Liaoning Institute of Geological Exploration Co., Ltd., Dalian 116199, China
5
Liaoning Metallurgical Geological Exploration Research Institute Co., Ltd., Anshan 114000, China
*
Author to whom correspondence should be addressed.
Minerals 2025, 15(9), 996; https://doi.org/10.3390/min15090996
Submission received: 30 July 2025 / Revised: 11 September 2025 / Accepted: 16 September 2025 / Published: 19 September 2025
(This article belongs to the Special Issue Selected Papers from the 7th National Youth Geological Congress)
Browse Figures
Versions Notes

Abstract

The Hugushan banded iron formation (BIF) is one of the most representative iron ore deposits in the central part of the North China Craton, and its ore formation mechanism remains highly controversial. This study presents whole-rock and Fe–Si–O isotope geochemical evidence, offering a new perspective on the ore formation mechanism of the Hugushan BIFs. The samples from the upper and lower parts of the Hugushan BIFs are characterized by slight enrichment of heavy and light Fe isotopes, respectively. Additionally, the samples from the upper part of the Hugushan BIFs show characteristics of slightly positive Ce anomalies and negative La anomalies, suggesting that the shallow ancient seawater was in a partially oxidized state, whereas the deep seawater remained in a reductive environment during the depositional period. The low Al2O3 and TiO2 concentrations, as well as the depletion of Zr and Hf in the Hugushan BIFs, suggest that the contribution of terrestrial detrital materials to deposition is extremely limited. The BIFs all exhibit positive Eu anomalies, and the quartz in the BIFs is depleted in 30Si, a characteristic similar to that observed in siliceous rocks formed in hydrothermal vent environments and during hydrothermal plume activity. Additionally, the δ18O values of quartz in Hugushan BIFs are similar to the O isotope compositions of hydrothermal sedimentary siliceous rocks, further suggesting that the silicon in BIFs originates primarily from seafloor hydrothermal activity. The combination of Eu/Sm, Sm/Yb, and Y/Ho ratios indicates that the major components (iron and silica) of the Hugushan Iron Ore Deposit originated from the mixing of high-temperature hydrothermal fluids with seawater, with the hydrothermal fluid contributing slightly less than 0.1%. The magnetite and quartz bands in the BIFs exhibit inhomogeneous and covariant δ56Fe and δ30Si isotope characteristics, suggesting that the alternating siliceous and ferruginous layers are products of original chemical deposition in the ocean. Periodic hydrothermal activity and ocean transgression caused the recurring deposition of siliceous and ferruginous layers, resulting in the characteristic banded structure of the Hugushan Iron Ore Deposit.

1. Introduction

Banded iron formations (BIFs) are metamorphic chemical sedimentary rocks formed during the Precambrian [1]. BIF-type iron ore deposits are one of the most important iron ore resources in the world, accounting for approximately 60–70% of the global iron ore reserves [1]. Formation of BIF-type iron ore deposits occurred over a vast timespan, ranging from 3.8 to 0.6 Ga, with two major mineralization stages of 2.8–1.8 Ga and 0.8–0.6 Ga [2]. As products formed at specific stages of early Earth history, the mineralization processes epitomize the coupling of geological evolution and environmental changes. Accordingly, BIFs are not only important iron-enriched rocks, but also crucial carriers for studying the tectonic evolution and environmental changes of the Earth.
Sedimentary facies of BIFs can be subdivided into four facies, i.e., sulfide, oxide, silicate and carbonate facies, and they are integrated manifestations of paleoclimate, paleoenvironment, and tectonic setting. Oxide facies is the dominant lithology [3], which is found as two principal types, one characterized by magnetite-banded rocks and the other by hematite-banded rocks. Both magnetite- and hematite-banded rocks are characterized by the presence of silicalite or carbonate interlayers. Principal iron-bearing minerals of oxide facies include magnetite, hematite and pyrite, and associated minerals are mainly quartz and calcite. As chemically and/or biochemical sedimentary rocks, the main ore-forming elements are relatively simple, mainly including Fe, Si, O and C. Additionally, since the formation of BIFs is mostly related to submarine volcanism and terrestrial clastic sediments, BIFs have generally preserved S, Mn, Al, Ti and trace elements similar to their source. Therefore, Fe-Si-O and whole-rock geochemical studies can provide crucial information on the mineralization mechanism of BIFs.
BIFs are widely distributed in the North China Craton, primarily in the Anshan–Benxi and the Wutai–Lvliang metallogenic belts [4]. Previous studies have mainly focused on the genesis of BIF-type deposits in the Anshan–Benxi area [5,6]. However, the mineralization mechanism of BIFs in the Wutai–Lvliang metallogenic belt is still controversial due to the lack of relevant studies on mineralization mechanisms. The Wutai–Lvliang metallogenic belt is mainly composed of three iron ore deposits, from north to south, including Yuanjiacun Iron Ore Deposit, Hugushan Iron Ore Deposit and Jianshan Iron Ore Deposit. The Hugushan Iron Ore Deposit located in the middle zone is highly representative in terms of the ore types and depositional environments [7,8,9]. Previous studies have not found volcanic rocks in the Hugushan area [8]. Moreover, the Hugushan Iron Ore Deposit has developed hematite within the BIFs and hornblende-type magnetites in the upper and lower parts, respectively [8]. A depositional environment may occur in the redox transition zone and the underlying reducing water column. Therefore, the metallogenic model of the Hugushan Iron Ore Deposit is unique and has sparked extensive debates regarding its depositional environment and mineralization mechanism. According to petrology, whole-rock geochemical analysis, and Si-Fe-O isotope characterization studies, we propose that the siliceous and ferruginous layers of the Hugushan BIFs are products of original chemical deposition in the ocean. Periodic hydrothermal activity and ocean transgression caused the recurring deposition of siliceous and ferruginous layers, resulting in the characteristic banded structure of the Hugushan Iron Ore Deposit. However, the unique metallogenic model of the Hugushan Iron Ore Deposit has sparked extensive debates regarding its depositional environment and mineralization mechanism [9]. First, the ancient atmospheric and oceanic redox states remain poorly understood. Second, the contributions of volcanic hydrothermal activity and terrestrial clastic materials to the formation of BIFs remain unresolved. Third, it is essential to evaluate the roles of biotic oxidation and microbial dissimilatory iron reduction (DIR) in the mineralization processes of BIFs, as microbial metabolism, particularly in the late Archean, played a significant role in shaping these ancient environments. The evolution of Fe-Si-O isotopes can provide unique insights into sources of ore-forming elements and oceanic redox conditions. Combined with whole-rock geochemical analysis, the mineralization processes can be effectively reconstructed, shedding light on the complex interplay between geological, chemical, and potentially biological factors that contributed to the formation of the BIF deposits.
In this study, whole-rock geochemical analysis and Si–Fe–O isotope characterization studies were conducted to investigate the source of materials, the depositional environment, and the mechanism underlying the genesis of Hugushan BIF-type iron ore deposits.

2. Geological Setting

2.1. Regional Geology

The North China Craton has been subjected to tectonic evolution over approximately 3.8 Ga and is considered one of the oldest cratons globally [10]. The Hugushan BIFs are located at the western margin of the Central Orogenic Belt of the North China Craton and represent the result of early Proterozoic evolution of the North China Craton (Figure 1a). Hugushan is characterized as a typical BIF deposit that developed within a series of Paleoarchean rift basins on an Archean crystalline basement. The regional stratigraphy from bottom to top comprises the following three principal sequences: (1) Archean strata that constitute the basement formed by BIFs, exemplified by the Jiehekou Group; (2) Paleoproterozoic strata comprising iron-bearing rock series and former continental shelf deposits represented by the Lvliang Group (containing the Yuanjiacun, Peijiazhuang, Jinzhouying, and Dujiagou Formations), the Yejishan Group, and the Lanhe Group; and (3) Cambrian strata that constitute the carbonate sedimentary cover (Figure 2).
The Precambrian granitic intrusions in the study area can be divided into three types. The first type encompasses the earliest-formed 2364–2180 Ma tonalite–trondhjemite–granodiorite (TTG) [12,19]. The second type is subsequently represented by weakly metamorphosed gneissic granites with an age of ca. 1906 Ma [13]. Finally, the third type includes undeformed granites with ages ranging from 1815 to 1790 Ma [19].
The fault structures in this area exhibit significant variations in their depth and orientation. Their activity has persisted over an extended geological period, with the distribution of Proterozoic strata directly influenced by these structural features. The fractures are oriented primarily along NNE- and E-W-trending directions. NNE-trending fractures are distributed along the tectonic and lithological boundaries of the Yejishan Group, Jiehekou Group, and eastern Chijianling granitic gneiss. E-W-trending fractures are mainly represented by the Xichuanhe shear zone. This shear zone divides the Lvliang Group into two regions north and south of Xichuanhe, serving as a boundary (Figure 1b).

2.2. Mine Geology

The main strata in the mining area are the Yuanjiacun Formation and Peijiazhuang Formation of the lower Proterozoic Lvliang Group, as well as the Cambrian System. The Yuanjiacun Formation, which serves as the primary iron-bearing stratum, comprises the following lithologies: carbonaceous schist, chlorite–actinolite schist, epidote–amphibolite schist, quartz schist, magnetite quartzite, amphibolite, and quartz sericite schist. Overall, it comprises metamorphosed clastic sedimentary rocks and metamorphosed mafic volcanic rocks. The Peijiazhuang Formation conformably overlies the Yuanjiacun Formation, which primarily comprises pyritic argillite, metamorphosed sandstone, carbonaceous argillite, sericite quartzite containing glaucophane, and quartzite. The Cambrian System unconformably overlies the Yuanjiacun Formation strata, with limestone as the main lithology. In the Yuanjiacun Formation, two layers of BIFs developed, with a length of approximately 6.2 km and thicknesses ranging from 2 to 50 m. These BIFs extend NNW (Figure 3a,b). The magmatic rocks in the mining area occur primarily in the eastern and central parts of the area and are dominated by gneissic granites and metamorphic quartz porphyry. Moreover, the western part of the mining area is characterized by the development of basic dykes trending approximately NNW, which caused a significant reduction in ore body integrity.

3. Sample Description and Analytical Methods

The Hugushan open-pit mine mainly consists of two types of rocks: the lower segment is composed of hornblende quartz magnetite, and the upper segment is magnetite quartzite. Samples were collected from recently exposed iron ores in the open-pit mine; sample numbers increase from top to bottom (Figure 4), including 4 magnetite quartzite samples and 5 amphibole quartz magnetite samples (Table A1, Table A2 and Table A3). Amphibole quartz magnetite exhibits a banded texture with a granoblastic structure. The major mineral components are quartz (~25%), amphibole (~10%), magnetite (~62%), and pyrite (~3%) (Figure 5a,b). Magnetite occurs as subhedral to anhedral grains (0.1–0.2 mm) and is concentrated within dark bands (1–6 mm in width) in disseminated and banded arrangements. The light-colored bands are largely devoid of magnetite. Pyrite (subhedral to anhedral; 0.1–0.2 mm) is sparsely distributed (Figure 4b). The magnetite quartzite exhibits banded and granular metamorphic textures. The light-colored bands are 0.15–0.8 mm wide, whereas the dark-colored bands measure 0.4–1.0 mm in width. The major minerals are quartz (60%) and magnetite (40%) (Figure 5c,d). Quartz exhibits a granular xenomorphic texture, with grain sizes ranging from 0.02 to 0.04 mm, and is intergrown with magnetite.

3.1. Major and Trace Element Analyses

Major, trace, and rare-earth element (REE) concentrations were analyzed at the Langfang Regional Geological Survey. Major element contents were determined by loss-on-ignition (LOI) following the procedure of Chen et al. [21]. Massive samples of the Hugushan BIF were ground to ~200 μm. Approximately 0.7 g of the powdered sample was weighed into a ceramic crucible and heated at 1100 °C to constant weight; the LOI was then calculated after cooling. A mixed flux of Li2B4O7, LiF, and NH4NO3 was added to the sample and homogenized, followed by the addition of LiBr solution and drying. The mixture was fused at 1150–1250 °C to produce glass disks, which were analyzed with an Axios-mAX wavelength-dispersive X-ray fluorescence (WDXRF), Malvern Panalytical, Malvern, UK spectrometer. Certified reference material GSR-15 was prepared and analyzed together with each batch of samples. Analytical precision was ≥1%, and the relative standard deviation (RSD) was <2.5%.
Trace element and rare-earth element (REE) analyses were performed using high-purity reagents. Water was treated through an ion-exchange purification system to ensure that all target elements were below the method detection limits. Samples were prepared by acid digestion: 50 mg of powdered material was weighed and dissolved in a mixture of HNO3 and HF. The resulting solution was transferred to a polyethylene bottle and diluted to 50 mL with ultrapure water. Elemental concentrations were determined on a NexION 300D inductively coupled plasma mass spectrometer (ICP-MS). Blank solutions of the laboratory reagents were measured concurrently, with reagents drawn from the same stock and added in equivalent volumes. National certified reference materials (GSR-2, CSD-12) were analyzed alongside the samples for quality control. Analytical precision was ≥2‰, and the relative standard deviation (RSD) was <5%. The detailed results are provided in Table A1.

3.2. Fe Isotope Analyses

The Fe isotopic compositions of magnetite were analyzed at Beijing Createch Testing Technology Co., Ltd., following the procedure described by [22]. The samples were first dissolved in aqua regia and subsequently oxidized to Fe3+ in nitric acid. Fe was separated through an ion-exchange chromatography column. Fe isotopic ratios were measured in high-resolution mode using a Thermo Scientific Neptune Plus multi-collector inductively coupled plasma mass spectrometry (MC–ICP–MS) instrument, Thermo Scientific Neptune, Waltham, MA, USA, calibrated via standard-sample bracketing, and the data are reported as δ56Fe values relative to the IRMM-014 standard.
δ56FeIRMM-014 = [(56Fe/54Fe)sample/(56Fe/54Fe) IRMM-014 − 1] × 1000
δ57FeIRMM-014 = [(57Fe/54Fe)sample/(57Fe/54Fe) IRMM-014 − 1] × 1000
On the basis of standard sample measurements, the analytical precisions for δ56Fe and δ57Fe were 0.08‰ (2×standard deviation (SD)) and 0.14‰ (2SD), respectively. For δ56Fe, the BCR-2 and BIR-1 values were 0.10‰ ± 0.07‰ and 0.03‰ ± 0.08‰, respectively. For δ57Fe, the corresponding values were 0.14‰ ± 0.09‰ and 0.05‰ ± 0.11‰, respectively. These results conform with those of previous studies [18]. Detailed results are listed in Table A2.

3.3. Quartz O–Si Isotopic Compositions

Chemical separation and determination of O–Si isotopic compositions were conducted at Nanjing Hongchuang Geological Exploration Technology Service Co., Ltd. The samples for O-Si analysis were ground to ~200 μm. Subsequently, 6 mg of a pure sample was weighed and placed in an oven at 105 °C for drying over 12 h.
Oxygen isotope analysis of the samples was conducted via the traditional BrF5 method [23]. Mineral-bound oxygen was extracted by reacting BrF5 with oxygen-bearing minerals under vacuum at 580 °C. The released O2 gas was collected in a sample tube packed with silica gel. The external analytical precision for the standard samples was greater than ±0.2‰, as determined using Vienna standard mean ocean water (V-SMOW) as the reference standard. Analyses were performed with a Thermo Scientific 253 Plus gas isotope ratio mass spectrometer.
δ18OSMOW = [(18O/16O)sample/(18O/16O)SMOW − 1] × 1000
The silicon isotope samples were reacted with BrF5 under vacuum at 580 °C to produce SiF4 gas. The generated SiF4 was purified repeatedly via acetone–dry ice traps, followed by further purification through a metallic zinc tube at 60 °C to obtain high-purity SiF4 for mass spectrometry. The analytical procedures followed those described by [24]. The results are reported in δ notation, with NBS-28 serving as the standard, as detailed below:
δ30SiNBS-28 = [(30Si/28Si)sample/(30Si/28Si)NBS-28 − 1] × 1000
The external reproducibility for the standard samples (with NBS-28 as a reference) was greater than ±0.1‰. Measurements were performed using a MAT 253 Plus gas isotope ratio mass spectrometer. Detailed Si–O isotope analysis results are provided in Table A3.

4. Analytical Results

4.1. Whole-Rock Geochemistry

The compositions of major and trace elements in the seven collected samples are provided in Table A1. All the samples primarily comprise total iron oxide (Fe2O3T) and silicon dioxide (SiO2), which exhibit a significant negative linear correlation. These components are accompanied by minor amounts of aluminum oxide (Al2O3), calcium oxide (CaO), and magnesium oxide (MgO) (Table A1) (Figure 6). The SiO2 contents in the three amphibole quartz magnetite samples (samples 23W3-4, 23W3-5, and 23W3-7) range from 15.52 wt. % to 19.12 wt. % (average: 17.29 wt. %), whereas the Fe2O3T contents range from 76.31 wt. % to 79.68 wt. % (average: 77.88 wt. %). In comparison, the four magnetite quartzite samples (samples 23W2-1, 23W2-2, 23W2-3, and 23W2-10) contain SiO2 contents ranging from 43.72 wt. % to 51.08 wt. % (average: 46.07 wt. %) and Fe2O3T contents ranging from 44.34 wt. % to 52.73 wt. % (average: 50.08 wt. %). All samples exhibited low Al2O3, CaO, MgO, K2O, Na2O and TiO2 concentrations.
In the primitive mantle-normalized spider diagram (Figure 7a,b), the two rock types from Hugushan exhibit similar characteristics. They are enriched in large-ion lithophile elements (LILEs), such as Rb, Sr, and K, and depleted in high-field strength elements (HFSEs), such as Nb, Zr, and Hf. Magnetite quartzite is significantly depleted in Ti, whereas amphibole quartz magnetite is relatively enriched in Ti. Both rock types exhibit relative depletion in light rare-earth elements (LREEs) and enrichment in heavy rare-earth elements (HREEs), with (La/Yb)SN ratios ranging from 0.17 to 0.28 (average: 0.21). Additionally, they demonstrate positive Eu anomalies (Eu/Eu* = 1.81–2.75; average: 2.25), La depletion (La/La* = 0.57–0.94; average: 0.79), and no significant Ce anomalies (Ce/Ce* = 0.85–1.20; average: 1.02).

4.2. Fe, Si and O Isotopic Compositions

The magnetite in the amphibole quartz magnetite samples exhibits a δ56FeIRMM-014 value ranging from −0.21‰ to −0.11‰, with a corresponding δ57FeIRMM-014 value ranging from −0.31‰ to −0.16‰ (Table A2). In contrast, the magnetite in the three magnetite quartzite samples exhibits δ56FeIRMM-014 values ranging from 0.01‰ to 0.38‰, with corresponding δ57FeIRMM-014 values ranging from 0.02‰ to 0.55‰. The average δ56FeIRMM-014 values for amphibole quartz magnetite and magnetite quartzite are −0.16‰ and 0.20‰, respectively (Figure 8). The δ30SiNBS-28 value of quartz grains separated from amphibole quartz magnetite range from −2.1‰ to −0.9‰, while those of quartz grains separated from the three magnetite quartzite samples range from −1.3‰ to −1.1‰ (Figure 9). The quartz in the amphibole quartz magnetite samples exhibits a δ18O value ranging from 11.43‰ to 13.79‰, whereas the δ18O values of the magnetite quartzite samples range from 13.16‰ to 15.83‰ (Figure 10; Table A3).

5. Discussion

5.1. Depositional Environment

The redox conditions of ancient oceans played a crucial role in the formation of BIFs. The availability and speciation of iron in ancient seawater were largely governed by the prevailing redox conditions, which in turn influenced the precipitation and accumulation of iron-rich sediments. The trace element and isotope analyses for the BIF rock can help to reconstruct the redox conditions of ancient seawater during the depositional processes of the Hugushan BIFs. Our trace element and Fe isotope analysis can provide new insights into the redox state of ancient ocean, which further advance our understanding of the formation and distribution of BIFs.
Fe isotope fractionation occurs during the redox reactions, precipitation, dissolution, adsorption, biological absorption, and complexation of organic matter [40]. In comparison, the oxidation process in ancient oceans is the most significant factor in Fe isotope fractionation [40]. Fe commonly exists in multiple oxidation states (0, +2, and +3), and the oxidation of Fe2+ to Fe3+ leads to significant iron isotope fractionation, resulting in a strong enrichment of heavy iron isotopes in BIF [41,42]. In turn, the variation in Fe isotopes can effectively indicate the redox state of ancient seawater [43,44]. It is worth noting that the Hugushan BIFs have experienced amphibolite-facies metamorphism, which may have significantly altered the original Fe isotope composition of the BIF. Therefore, it is necessary to evaluate the effects of metamorphism. The δ56Fe values of the magnetite grains from the Hugushan BIFs yield inhomogeneous Fe isotopes (Figure 8). Moreover, the observed inhomogeneity of Fe isotopes among different magnetite grains within the same sample also suggests that our samples have retained their original Fe isotope signatures. The δ56Fe values of magnetite grains from the Hugushan BIFs range from −0.21‰ to 0.38‰, with an average value of −0.01‰, suggesting that the Hugushan BIFs are slightly enriched in light iron isotope. The results indicate that the BIF deposition took place under persistently low-oxygen to anoxic conditions, where the fO2 of Archean seawater was limited. It is worth noting that the magnetite quartzites in the upper part of Hugushan BIFs generally have positive δ56Fe values, while the amphibole quartz magnetites in the lower part produce negative δ56Fe values, indicating that the seawater in the upper part was in a partially oxidized state.
The trace elements also serve as a crucial indicator of redox conditions in the depositional environment [45,46]. However, since the trace elements may have been affected by the amphibolite-facies metamorphism, it is necessary to assess the migration in our samples [47]. The lack of metasomatic veins or alteration halos is indicative of the limited fluid-mediated element mobility. In addition, the element mobility indexes (EMI = ([La + Yb]sample/[La + Yb]PAAS) × ([K + Rb]sample/[K + Rb]PAAS)) of our samples are less than 0.01, suggesting that the components of trace elements are not affected by diagenesis and regional and contact metamorphism [47,48]. Ce typically exists as Ce3+ in natural systems, but it can be oxidized to Ce4+ in oxygen-rich environments. Negative Ce anomalies in seawater typically result from the oxidation of Ce3+ to Ce4+. This oxidation leads to the formation of less soluble Ce4+ species and/or preferential adsorption of Ce4+ onto particle surfaces, thereby decoupling Ce from other trivalent rare-earth elements (REEs) [49]. When examining Ce anomalies in aqueous systems, the presence of Mn oxides should be considered, as Ce is preferentially incorporated into natural Mn oxides relative to other REEs [50]. This selective incorporation is attributed to the oxidative scavenging of dissolved Ce3+ by Mn oxides [51,52,53,54,55]. The magnetite quartzites and amphibole quartz magnetites in the Hugushan BIFs yield MnO2 contents of 0.03–0.05 and 0.13–0.17, respectively. Combined with the low content of MnO2, a lack of Mn oxides has been found in our samples (Table A1), further suggesting that the Ce anomaly is predominantly governed by the redox conditions of the depositional environment.
Three amphibole quartz magnetite samples show characteristics of positive Ce anomalies (1.16–1.20), whereas four magnetite quartzite samples show slightly to strongly negative Ce anomalies (0.85–0.97). The results suggest that the seawater was partially oxidized during the depositional period, but the deep seawater was still in a low-oxygen state. Additionally, the conclusion is also supported by the La anomaly. The La anomaly serves as a valuable indicator of the redox conditions in ancient oceans [44]. Typically, positive La anomalies are associated with anoxic seawater environments, whereas negative La anomalies suggest oxidizing conditions. Three amphibole quartz magnetite samples and two magnetite quartzite samples show strongly negative La anomalies (La/La* = 0.57–0.84), whereas the residual two magnetite quartzite samples show slightly negative Ce anomalies (La/La* = 0.91–0.94). The results are indicative of a partially oxidized environment. The Ce/Ce*–Pr/Pr* discrimination diagram also shows that the ancient seawater was partially oxidized (Figure 11) [48,56].
Based on the analysis of Fe isotopes and trace elements, it is inferred that the shallow seawater was in a partially oxidized state, whereas the deep seawater remained in a reductive state during the depositional period. Compared to the adjacent Yuanjiacun BIFs and Jianshan BIFs, the Hugushan BIFs located in between are more enriched in light iron isotopes. Moreover, the deep-seated amphibole quartz magnetites in the Hugushan BIFs are more enriched in light iron isotopes than the shallow magnetite quartzites. These results indicate that the Hugushan BIFs are situated in the center of the basin, where the oxidation degree of shallow seawater is higher than that of deep seawater. In addition, this conclusion is similar to that observed in other global regions (Figure 8) [5,28,29,30,31,32,33]. In comparison, the BIFs in the Anshan–Benxi area are relatively enriched in heavy iron isotopes, but the deep-seated ore bodies are more enriched in light iron isotopes compared to the shallow ones, suggesting that the upper BIFs were formed in a sedimentary environment with a higher degree of oxidation.

5.2. Origin of the Major Components (Iron and Silica) of BIFs

The minerals in the BIFs were derived primarily from two main sources: terrigenous detritus and submarine hydrothermal fluids [57,58,59]. Among them, submarine hydrothermal fluids were derived from the seafloor volcanoes which carried large amounts of elements such as iron, silicon and REEs. When these elements came into contact with cold seawater, they reacted to form depositional minerals with low solubility, which subsequently precipitated out of the solution [5,60,61,62]. Therefore, the relative contributions of terrigenous detritus and hydrothermal fluids to ore formation can be obtained on the basis of whole-rock geochemistry and Si-O isotopes.
The low Al2O3 and TiO2 concentrations in the Hugushan iron ores indicate a minimal contribution of terrigenous detritus to the major components (iron and silica) of BIFs [63,64,65,66]. In addition, elements such as Zr, Hf, Sc, and Th can be used to determine the contribution of terrigenous detrital materials [67,68,69,70]. The Hugushan BIFs exhibit significant depletion in both Zr and Hf, with low concentrations of Sc (0.70 × 10−6 to 7.70 × 10−6) and Th (0.15 × 10−6 to 1.34 × 10−6). These geochemical features collectively also suggest a minimal contribution of terrigenous materials to mineralization.
Eu can be used to trace the nature of ore-forming fluids. High-temperature fluids typically exhibit positive Eu anomalies [71,72,73], whereas low-temperature fluids exhibit negative Eu anomalies [74]. All samples from the Hugushan BIFs exhibited positive Eu anomalies, indicating that the formation of the ore deposit was closely related to high-temperature hydrothermal fluids [75]. In addition, the quartz in all samples is depleted in δ30Si (−2.1‰ to −0.9‰), with silicon isotopic compositions resembling those of quartz in seafloor black-smoker environments and hydrothermal plume-related cherts [76,77] (Figure 9). This similarity strongly suggests that the silicon in the BIFs is derived primarily from seafloor hydrothermal activity. The δ18O values of quartz in Hugushan BIFs are distributed between 11.43‰ and 15.83‰ (Figure 10), which lie between those of igneous rocks and marine siliceous rocks formed at normal temperatures, and are similar to the oxygen isotope compositions of hydrothermal sedimentary siliceous rocks. This suggests that the Hugushan BIFs were formed in a hot-water environment, a conclusion also supported by whole-rock geochemistry.
In the Al2O3–SiO2 discrimination diagram, all samples occur within the hydrothermal field, validating the aforementioned conclusion [78] (Figure 12). The nature of the ore-forming fluids can also be characterized by the ratio of Y to Ho. Typically, the Y/Ho ratio in seawater is greater than 44, whereas in hydrothermal fluids, this ratio is approximately 28 [79]. When hydrothermal fluids mix with seawater, fractionation of Y and Ho occurs. With a decreasing proportion of hydrothermal fluid, the Y/Ho ratio increases [80]. In the Hugushan BIFs, the Y/Ho ratios (28.02–33.94) in amphibole quartz magnetite are slightly higher than those in hydrothermal fluids but significantly lower than those in seawater. These findings indicate that the ore-forming process involved the combined action of hydrothermal fluids and seawater. Additionally, the Eu/Sm and Sm/Yb ratios also suggest that the major components (Fe and Si) of BIFs were derived from mixing of hydrothermal fluids and seawater. Since the ancient seawater contained virtually no Fe, the hydrothermal end-member might supply the bulk of the iron, with the hydrothermal end-member contributing less than 0.1% (Figure 13). According to the covariation of δ56Fe and Ce anomalies in our samples, all data are plotted along the mixing trend of hydrothermal fluid and seawater, further indicating that iron was gradually mobilized and subsequently enriched and precipitated with the progressive oxidation of ancient seawater (Figure 14).
In conclusion, the mixture of high-temperature hydrothermal fluids and seawater provided the major components (iron and silica) of BIFs. Submarine volcanic activities erupt large amounts of magmatic hydrothermal fluids. These high-temperature fluids are rich in Fe and Si elements. After mixing with cold seawater, some of the Fe and Si elements dissolve in the seawater. With the increase in Fe and Si elements in the seawater, the precipitation of iron oxides and silicate minerals is promoted. The above conclusion is consistent with the ore-forming mechanism of the BIFs in the Anshan–Benxi area [82]. As a typical Algoma-type iron ore deposit, the formation of BIFs in the Anshan–Benxi area is closely related to volcanic activity [5,82,83]. During submarine volcanic eruptions, the magma contains large amounts of Fe and Si elements. When the magma erupts onto the seafloor, it cools rapidly to form volcanic rocks, which are rich in Fe and Si elements. These volcanic rocks undergo weathering and erosion in seawater, providing a substantial source of material to the ancient ocean.

5.3. Genesis of BIFs

As a marine chemical sedimentary formation, the most typical attribute of BIFs is the presence of alternating siliceous and ferruginous layers. The formation mechanisms of these alternating layers involve mainly the transport and precipitation of iron [84,85]. By comparing the Fe–Si isotope variations between different siliceous and ferruginous bands, key evidence for interpreting the genesis of BIFs can be obtained.
There are two main perspectives regarding the genesis of BIFs: (1) periodic biological oxidation or (2) primary marine chemical sedimentation [84,86,87]. In the Hugushan BIFs, microlaminated structures are preserved, which indicate that the primary sedimentary iron-rich minerals exhibit a low degree of metamorphic modification. Although there is no direct evidence that the Hugushan BIFs are colloidal precipitates, the metamorphic quartz sandstone in the overlying iron ore layer encompasses a relict detrital structure of quartz. The quartz grains are subrounded with favorable sphericity, and the cement has been metamorphosed into fine-grained siliceous material, which is distributed between relict quartz grains, also indicating that the sandstone is a product of shallow-marine primary sedimentation [88,89,90,91]. In addition, the magnetite and quartz from Hugushan BIFs all exhibit inhomogeneous and covariant δ56Fe and δ30Si isotope characteristics (Figure 8 and Figure 9), indicating that the alternating siliceous and ferruginous layers are products of primary marine chemical sedimentation.
The degree of Si-Fe isotopic enrichment can indicate the sequence of precipitation of the original sedimentary minerals [41,42]. Under the same temperature conditions, the silicon isotopic composition of the siliceous components that precipitate first is lower, whereas that of the siliceous components that precipitate later is higher [76,77,92]. The siliceous and ferruginous layers of the Hugushan BIFs are characterized by low δ30Si isotope values in the lower quartz bands, indicating clear regularity in the precipitation of ancient marine silica. Considering the saturation of silicon and iron in seawater, it is likely that silica precipitated first and that iron precipitated later during the formation of the original BIFs. In addition, the precipitation mechanism can be effectively characterized by the fractionation of Fe isotopes. Under the same redox conditions, the minerals that precipitate first are more enriched in heavy iron isotopes, while those that precipitate later are more enriched in light iron isotopes [33]. During the precipitation processes, Fe isotopes experience significant mass-dependent fractionation. Specifically, the precipitate would be enriched in heavy Fe isotopes (such as 56Fe) compared to the dissolved Fe2+ in the solution. Since the oxidation degree of deep ancient seawater is very low, it still contains substantial amounts of dissolved Fe2+. Further, each episode of iron precipitation represents only a small fraction of the total dissolved iron in the ocean. Moreover, the dissolved iron reservoir can be continuously replenished by hydrothermal activities. Consequently, the δ56Fe value of primary precipitate remains consistently high and positive [9]. Based on the principle of mass balance, as precipitation progresses, the Fe isotope composition of the residual solution becomes progressively lighter, forming a reservoir enriched in light Fe isotopes. As a result, iron-bearing minerals precipitated early are enriched in heavy iron isotopes, while those that form later are enriched in light iron isotopes. The δ56Fe values of amphibole quartz magnetites are all negative, which is indicative of an anoxic environment. Moreover, δ56Fe values show a trend toward enrichment of light iron isotopes from the bottom of the sedimentary profile upward. This could be attributed to the cyclic precipitation of iron minerals in seawater, a process regulated by fluctuations in redox potential (Eh) and pH, which can be induced by ocean transgression or ocean acidification.
According to the major components (iron and silica) and metallogenic mechanism, the sedimentation process of BIFs can be roughly divided into three stages (Figure 15). (1) Initial mixing and precipitation: Hydrothermal fluids rich in iron and silicon mixed with seawater, causing a rapid decrease in temperature. The temperature decrease led to silicon saturation in seawater, thus yielding siliceous layers [9,24,75,76]. (2) Iron deposition controlled by redox conditions and precipitation sequence: As the temperature decreased and the pH increased, Fe2+ in the hydrothermal fluids was oxidized to Fe3+, which then precipitated as iron hydroxides. (3) Cyclical deposition: Periodic activity of the hydrothermal vents resulted in the alternating deposition of silica- and iron-rich layers, thereby creating the characteristic banded structure of the iron-rich rocks.

6. Conclusions

(1).
The shallow seawater was in a partially oxidized state, whereas the deep seawater remained in a reductive environment during the depositional period.
(2).
The primary mineralizing materials of the Hugushan BIF-type iron ore deposit mainly originated from the interaction between high-temperature hydrothermal fluids discharged from the seafloor and seawater, with a minor contribution from terrigenous materials.
(3).
The alternating siliceous and ferruginous layers of the Hugushan BIFs are primary sedimentary products, which might be attributed to the cyclic precipitation of iron and silicon in seawater.

Author Contributions

E.W.: writing—original draft preparation, funding acquisition and supervision. D.Z.: writing—original draft, investigation, artworks and reviewing. J.L.: reviewing and editing. Y.M.: reviewing and editing. R.W.: reviewing and editing. J.X.: reviewing and editing. S.Z.: reviewing and editing. All authors have read and agreed to the published version of the manuscript.

Funding

This work was financially supported by the National Key Research and Development Program of China (Grant No.2025ZD1007208), the National Natural Science Foundation of China (Grants 42202055), the Fundamental Research Funds for the Central Universities (N2401013), the science and technology plan project of Liaoning Province (2023-MSBA-132) and the open fund of Liaoning Key Laboratory of Green Development of Mineral Resources.

Data Availability Statement

Data is contained within the article.

Acknowledgments

Thanks are given to Rui Zhang from the Liaoning Technical University for his constructive suggestions and comments. Staff of the Nanjing Hongchuang Geological Exploration Technology Service Co., Ltd. provided assistance during Si-O isotope analyses. Staff of the Beijing Createch Testing Technology Co., Ltd. provided assistance during Fe isotope analyses. Staff of the Langfang Regional Geological Survey provided assistance during major, trace, and rare-earth element analyses.

Conflicts of Interest

Ran Wang is an employee of Liaoning Institute of Geological Exploration Co., Ltd. The paper reflects the views of the scientists and not the company. Suibo Zhang is an employee of Liaoning Metallurgical Geological Exploration Research Institute Co. The paper reflects the views of the scientists and not the company.

Appendix A

Table A1. Major and trace element compositions of BIFs from the Hugushan iron deposit.
Table A1. Major and trace element compositions of BIFs from the Hugushan iron deposit.
Sample23W2-123W2-223W2-323W2-1023W3-423W3-523W3-7
SiO245.5043.7244.0051.0815.5219.1217.24
Al2O30.800.720.710.861.391.241.34
Fe2O3T50.6452.7352.6244.3479.6876.3177.64
CaO0.781.280.782.062.141.971.85
MgO1.991.241.441.942.001.841.73
K2O0.140.110.110.110.220.180.17
Na2O0.680.510.420.040.090.060.08
TiO20.020.020.020.020.720.680.70
P2O50.110.160.060.350.110.150.13
MnO0.050.030.030.030.130.170.14
LOI−1.05−0.74−0.61−1.14−2.26−2.01−1.14
Total99.6499.7799.5999.6999.7599.7199.88
Li28.3227.1629.7215.1114.5114.3215.02
Be1.661.111.211.853.763.123.71
Sc0.700.741.542.027.707.367.64
V5.323.753.577.70214.70224.52235.14
Cr16.0521.6142.8335.1640.1239.1941.51
Co0.780.560.781.3221.8519.7824.72
Ni7.699.1613.7713.5528.2524.4527.77
Ga0.570.411.601.797.837.148.41
Rb2.271.021.072.9020.8322.7219.45
Sr15.4344.3820.7232.4571.2468.1372.15
Y4.525.695.8610.898.257.988.01
Zr4.634.163.125.313.583.643.24
Nb0.150.090.090.230.770.530.81
Cs0.200.100.081.036.966.876.91
Ba6.758.8720.9420.1864.5657.4168.42
La1.681.862.553.532.662.342.74
Ce2.983.184.968.378.047.818.35
Pr0.380.400.631.090.860.910.95
Nd1.361.422.163.953.553.423.95
Sm0.290.310.510.880.980.870.94
Eu0.20 0.21 0.26 0.52 0.41 0.37 0.44
Gd0.49 0.47 0.66 1.19 1.27 1.13 1.37
Tb0.10 0.10 0.13 0.24 0.26 0.25 0.25
Dy0.61 0.68 0.89 1.56 1.62 1.57 1.66
Ho0.16 0.17 0.21 0.38 0.37 0.37 0.39
Er0.51 0.61 0.71 1.23 1.08 1.04 1.03
Tm0.09 0.10 0.11 0.20 0.17 0.14 0.11
Yb0.52 0.63 0.67 1.26 1.07 1.03 1.22
Lu0.11 0.11 0.11 0.20 0.17 0.16 0.17
Hf0.17 0.15 0.11 0.18 0.22 0.21 0.19
Ta0.08 0.06 0.06 0.06 0.13 0.11 0.14
Tl0.04 0.02 0.02 0.04 0.12 0.13 0.11
Pb1.06 1.27 0.92 1.50 2.70 2.34 2.47
Th0.15 0.15 0.61 1.34 0.88 0.77 0.97
U0.05 0.03 0.03 0.08 0.33 0.27 0.29
δEu1.60 1.68 1.38 1.54 1.12 1.14 1.18
ΣREE9.48 10.24 14.57 24.59 22.50 21.41 23.57
LREE/HREE2.66 2.58 3.17 2.94 2.75 2.76 2.80
(La/Yb)SN0.24 0.22 0.28 0.21 0.18 0.17 0.17
(Sm/Yb)SN0.29 0.25 0.39 0.36 0.46 0.43 0.39
(δEu)SN2.63 2.75 2.24 2.51 1.81 1.85 1.94
(Ce/Ce*)SN0.86 0.85 0.89 0.97 1.20 1.19 1.16
(Nd/Yb)SN0.22 0.19 0.27 0.26 0.28 0.28 0.27
(Gd/Gd*)SN0.72 0.67 0.72 0.69 0.78 0.73 0.84
La/La*0.91 0.94 0.76 0.67 0.84 0.57 0.80
Y/Ho28.02 33.94 28.02 28.80 22.30 21.57 20.54
Eu/Sm0.68 0.68 0.51 0.59 0.42 0.43 0.47
Sm/Yb0.56 0.49 0.76 0.70 0.91 0.84 0.77
Ce/Ce* = 2 CeN/(LaN + PrN); Gd/Gd* = 2GdN/(EuN + DyN). Subscript SN denotes that samples are normalized by the post-Archean Australian shale.
Table A2. Fe isotopic compositions of magnetites in the BIFs from the Hugushan iron deposit.
Table A2. Fe isotopic compositions of magnetites in the BIFs from the Hugushan iron deposit.
SampleDescriptionSubjectδ56Fe (‰)2σδ57Fe (‰)2σ
23W2-2Magnetite quartziteMagnetite0.380.010.550.05
23W2-3Magnetite quartziteMagnetite0.210.030.310.01
23W2-10Magnetite quartziteMagnetite0.010.020.020.02
23W3-5Amphibole quartz magnetiteMagnetite−0.110.06−0.160.03
23W3-6Amphibole quartz magnetiteMagnetite−0.130.03−0.190.02
23W3-7Amphibole quartz magnetiteMagnetite−0.190.05−0.260.03
23W3-8Amphibole quartz magnetiteMagnetite−0.210.05−0.310.03
Table A3. O and Si isotopic compositions of quartz in the BIFs from the Hugushan iron deposit.
Table A3. O and Si isotopic compositions of quartz in the BIFs from the Hugushan iron deposit.
SampleDescriptionSubjectδ18OV-SMOW (‰)δ30SiNBS-28 (‰)
23W2-2Magnetite quartziteQuartz15.50−1.1
23W2-3Magnetite quartziteQuartz15.83−1.3
23W2-10Magnetite quartziteQuartz13.16−1.1
23W3-5Amphibole quartz magnetiteQuartz13.79−0.9
23W3-6Amphibole quartz magnetiteQuartz12.62−1.5
23W3-7Amphibole quartz magnetiteQuartz11.95−1.7
23W3-8Amphibole quartz magnetiteQuartz11.43−2.1

References

  1. Hagemann, S.G.; Angerer, T.; Duuring, P.; Rosière, C.A.; Figueiredoe, S.R.C.; Lobato, L.; Hensler, A.S.; Walde, D.H.G. BIF-hosted iron mineral system: A review. Ore Geol. Rev. 2016, 76, 317–359. [Google Scholar] [CrossRef]
  2. Bekker, A.; Slack, J.F.; Planavsky, N.; Krapez, B.; Hofmann, A.; Konhauser, K.O.; Rouxel, O.J. Iron Formation: The Sedimentary Product of a Complex Interplay among Mantle, Tectonic, Oceanic, and Biospheric Processes. Econ. Geol. 2010, 105, 467–508. [Google Scholar] [CrossRef]
  3. James, R.H.; Elderfield, H.; Palmer, M.R. The chemistry of hydrothermal fluids from the broken spur site, 29-degrees-n mid-atlantic ridge. Geochim. Cosmochim. Acta 1995, 59, 651–659. [Google Scholar] [CrossRef]
  4. Shen, B.F.; Luo, H.; Jin, W.-S.; Li, S.B.; Chen, Y.H. Metallogenic model of the Archean BIF iron deposits in the North China Craton. Ore Geol. Rev. 2009, 35, 40–51. [Google Scholar]
  5. Fu, J.F.; Luan, J.P.; Jia, S.S.; Luo, Y.H.; Chen, J.D.; Zhao, F.Q. Fe-Si-C isotope constraints on the genesis of iron ores in Gongchangling iron deposit in northeastern China. J. Geochem. Explor. 2023, 250, 107233. [Google Scholar] [CrossRef]
  6. Tong, X.X.; Mänd, K.; Li, Y.H.; Zhang, L.C.; Peng, Z.D.; Wu, Q.; Li, P.B.; Zhai, M.G.; Robbins, L.J.; Wang, C.L. Iron and Carbon Isotope Constraints on the Formation Pathway of Iron-Rich Carbonates within the Dagushan Iron Formation, North China Craton. Minerals 2021, 11, 94. [Google Scholar] [CrossRef]
  7. Li, X.P.; Chen, Y.R. A brief discussion on the depositional and metamorphic mineralization of Precambrian banded iron formations. Acta Petrol. Sin. 2021, 37, 253–268. [Google Scholar]
  8. Wang, C.L.; Zhang, L.C.; Lan, C.Y.; Dai, Y.P. Rare earth element and yttrium compositions of the Paleoproterozoic Yuanjiacun BIF in the Luliang area and their implications for the Great Oxidation Event (GOE). Sci. China Earth Sci. 2014, 57, 2469–2485. [Google Scholar] [CrossRef]
  9. Tong, X.X.; Zhang, L.C.; Wang, C.L.; Peng, Z.D.; Zhai, M.G. Depositional and environmental constraints on the late Neoarchean Dagushan–Hugushan banded iron formation, North China Craton: An Algoma-type BIF with controversial genesis. Precambrian Res. 2021, 359, 106178. [Google Scholar]
  10. Zhai, M.G.; Guo, J.H.; Liu, W.J. Neoarchean to Paleoproterozoic continental evolution and tectonic history of the North China Craton. J. Asian Earth Sci. 2005, 24, 547–561. [Google Scholar] [CrossRef]
  11. Wang, H.C.; Miao, P.S.; Kang, J.L.; Ren, Y.W.; Zhang, J.H.; Li, J.R.; Xian, Z.Q.; Xiao, Z.B. New Evidence for the formation age of the Luliang Group. Acta Petrol. Sin. 2020, 36, 2313–2330. [Google Scholar]
  12. Zhao, G.C.; Wilde, S.A.; Sun, M.; Li, S.Z.; Li, X.P.; Zhang, J. SHRIMP U-Pb zircon ages of granitoid rocks in the Lüliang Complex: Implications for the accretion and evolution of the Trans-North China Orogen. Precambrian Res. 2008, 160, 213–226. [Google Scholar] [CrossRef]
  13. Wang, C.; Zhang, L.; Dai, Y.; Lan, C.Y. Geochronological and geochemical constraints on the origin of clastic meta-sedimentary rocks associated with the Yuanjiacun BIF from the Lvliang Complex, North China. Lithos 2015, 212, 231–246. [Google Scholar] [CrossRef]
  14. Geng, Y.S.; Wan, Y.S.; Shen, Q.H.; Li, H.M.; Zhang, R.X. Chronologic framework of the Early Precambrain imoportant events in the Luliang area, Shanxi Province. Acta Geol. Sin. 2000, 74, 216–223. [Google Scholar]
  15. Yu, J.H.; Wang, D.Z.; Wang, C.Y.; Li, H.M. Ages of the Lüliang Group and its main metamorphism in the Lüliang Mountains, Shanxi: Evidence from single-grain zircon U-Pb ages. Geol. Rev. 1997, 43, 403–408. [Google Scholar]
  16. Liu, S.W.; Zhang, J.; Li, Q.G.; Zhang, L.F.; Wang, W.; Yang, P.T. Geochemistry and U-Pb zircon ages of metamorphic volcanic rocks of the Paleoproterozoic Lüliang Complex and constraints on the evolution of the Trans-North China Orogen, North China Craton. Precambrian Res. 2012, 222–223, 173–190. [Google Scholar] [CrossRef]
  17. Wan, Y.S.; Geng, Y.S.; Shen, Q.H.; Zhang, R.X. Khondalite series- geochronology and geochemistry of the Jiehekou Group in Luliang area, Shanxi province. Acta Petrol. Sin. 2000, 16, 49–58. [Google Scholar]
  18. Li, J.X.; Hu, T.Y.; Liu, L. Metallogenie Age and Metallogenic Environment of Yuanjiacun lron Deposit in Shanxi Province. Earth Sci. 2023, 48, 12. [Google Scholar]
  19. Geng, Y.S.; Yang, C.H.; Wan, Y.S. Paleoproterozoic granitic magmatism in the Lüliang area, North China Craton: Constraint from isotopic geochronology. Acta Petrol. Sin. 2006, 22, 305–314, (In Chinese with English Abstract). [Google Scholar]
  20. Liu, Y.G. 3D Geological Modeling and Metallogenic Prediction of Hugushan Iron Deposit in Shanxi Province; Central South University: Changsha, China, 2023; pp. 1–102. [Google Scholar]
  21. Chen, J.Z.; Zhao, J.L.; Wang, C. Rock and Mineral Analysis, 4th ed.; Geological Publishing House: Beijing, China, 2011; pp. 1–904. [Google Scholar]
  22. Hou, K.J.; Li, Y.H.; Gao, J.F.; Liu, F.; Qin, Y. Geochemistry and Si-O-Fe isotope constraints on the origin of banded iron formations of the Yuanjiacun Formation, Lvliang Group, Shanxi, China. Ore Geol. Rev. 2014, 57, 288–298. [Google Scholar] [CrossRef]
  23. Clayton, R.N.; Mayeda, T.K. The use of bromine pentafluoride in the extraction of oxygen from oxides and silicates for isotopic analysis. Geochim. Cosmochim. Acta 1963, 27, 43–52. [Google Scholar] [CrossRef]
  24. Ding, T.P.; Jiang, S.Y.; Wan, D.F.; Li, Y.H.; Li, J.C.; Song, H.B.; Liu, Z.J.; Yao, X.M. Silicon Isotope Geochemistry; Geological Publishing House: Beijing, China, 1996; pp. 1–122. [Google Scholar]
  25. Sun, S.S.; McDonough, W.F. Chemical and isotopic systematics of oceanic basalts: Implications for mantle composition and processes. Geol. Soc. Spec. Publ. 1989, 42, 313–345. [Google Scholar] [CrossRef]
  26. McLennan, S.M. Rare earth elements in sedimentary rocks: Influence of provenance and sedimentary processes. Rev. Mineral. 1989, 21, 169–200. [Google Scholar]
  27. Beard, B.L.; Johnson, C.M.; Von Damm, K.L.; Poulson, R.L. Iron isotope constraints on Fe cycling and mass balance in oxygenated Earth oceans. Geol. Soc. Am. 2003, 31, 629–632. [Google Scholar] [CrossRef]
  28. Fantle, M.S.; DePaolo, D.J. Iron isotopic fractionation during continental weathing. Earth Planet. Sci. Lett. 2004, 228, 547–562. [Google Scholar] [CrossRef]
  29. Rouxel, O.; Dobbek, N.; Ludden, J.; Fouquet, Y. Iron isotope fractionation during oceanic crust alteration. Chem. Geol. 2003, 202, 155–182. [Google Scholar] [CrossRef]
  30. Zhu, X.K.; Guo, Y.L.; O’Nions, R.K.; Yound, E.D.; Ash, R.D. Isotopic homogeneity of iron in the early solar nebula. Nature 2001, 412, 311–313. [Google Scholar] [CrossRef] [PubMed]
  31. Rouxel, O.; Bekker, A.; Edwards, K.J. Iron isotope constraints on the Archean and Paleoproterozoic ocean redox state. Science 2005, 307, 1088–1091. [Google Scholar] [CrossRef]
  32. Dauphas, N.; Janney, P.E.; Mendybaev, R.A.; Wadhwa, M.; Richter, F.M.; Davis, A.M.; Zuilen, M.; Hines, R.; Foley, C.N. Chromatographic separation and multicollection-ICPMS analysis of iron. Investigating mass dependent and -independent isotope effects. Anal. Chem. 2004, 76, 5855–5863. [Google Scholar] [CrossRef]
  33. Johnson, C.M.; Beard, B.L.; Beukes, N.; Klein, C.; O’Leary, J.M. Ancient geochemical cycling in the Earthas inferred from Fe isotope studies of banded iron formations from the Transvaal Craton, Contrib. Mineral. Petrol. 2003, 144, 523–547. [Google Scholar] [CrossRef]
  34. Men, Y.K.; Mi, Z.J.; Wang, E.D.; Han, L.D.; Wang, Y.J.; Jia, S.S.; Xia, J.M.; Song, K. Geology and Geochemistry of the Jianshan Banded Iron Formation in Shanxi Province, China: Constraints on the Genesis. J. Geol. 2022, 130, 499–518. [Google Scholar] [CrossRef]
  35. Douthitt, C.B. The geochemistry of the stable isotopes of silicon. Geochim. Cosmochim. Acta 1982, 46, 1449–1458. [Google Scholar] [CrossRef]
  36. Taylor, H.P., Jr.; Sheppard, S.M.F. Igneous rocks: II. The processes of isotopic fractionation and isotope systematics. Rev. Mineral. 1986, 16, 227–271. [Google Scholar]
  37. Craig, H. Isotopic variations in meteoric waters. Science 1961, 133, 1702–1703. [Google Scholar] [CrossRef]
  38. Zhang, L.; Planavsky, N.J.; Wang, X.; Wang, G.; Reinhard, C.T. Silicon isotope evidence for widespread anoxic and iron-rich surface waters in Mesoproterozoic oceans. Earth Planet. Sci. Lett. 2020, 531, 115964. [Google Scholar]
  39. Ehlert, C.; Grasse, P.; Frank, M. Variations of silicic acid isotope composition (δ30Si) in the ocean: Reconstruction of marine weathering and reverse weathering. Geochim. Cosmochim. Acta 2016, 177, 1–18. [Google Scholar]
  40. Sun, J.; Zhu, X.K.; Li, S.Z. Iron Isotope Geochemical Behavior and Applications in Biological Processes. Acta Geol. Sin. 2015, 34, 777–784. [Google Scholar]
  41. Bullen, T.D.; White, A.F.; Childs, C.W.; Vivit, D.V.; Schulz, M.S. Demonstration of significant abiotic iron isotope fractionation in nature. Geology 2001, 29, 699–702. [Google Scholar] [CrossRef]
  42. Balci, N.; Bullen, T.D.; Witte-Lien, K.; Shanks, W.C.; Motelica, M.; Mandernack, K.W. Iron isotope fractionation during microbially stimulated Fe(II) oxidation and Fe(III) precipitation. Geochim. Cosmochim. Acta 2006, 70, 622–639. [Google Scholar] [CrossRef]
  43. Zhang, Q.; Liu, W.H.; Zhang, W.; Bai, H.F.; Li, Z.Y.; Wang, X.F.; Zhang, D.D.; Chen, X.Y.; Li, W.H. Formation conditions of Jixian System cherts in the Qishan area, Ordos Basin: Implications for marine redox conditions and paleoecology. Sediment. Geol. 2024, 467, 106651. [Google Scholar] [CrossRef]
  44. Kumar, R.; Hameed, A.; Tiwari, P.; Kumar, N.; Srivastava, P. Major, trace and rare earth element geochemistry of Archaean carbonate sediments of Tanwan group rocks of the Bhilwara supergroup, India: Implications for seawater geochemistry and depositional environment. Carbonates Evaporites 2024, 39, 14. [Google Scholar] [CrossRef]
  45. Shimizu, H.; Umemoto, N.; Masuda, A. Sources of iron-fommations in the Archean lsua and Malene supracrustals West Greenland Evidence from La-Ce and Sm-Nd isotopic data and REE abundances. Geochim. Cosmochim. Acta 1990, 54, 1147–1154. [Google Scholar] [CrossRef]
  46. Wheat, C.G.; Mottl, M.J.; Rudnicki, M. Trace element and REE composition of a low-Temperature ridge-flank hydrothermal spring. Geochim. Cosmochim. Acta 2002, 66, 3693–3705. [Google Scholar] [CrossRef]
  47. Bau, M. Effects of syn- and post-depositional processes on the rare-earth element distribution in Precambrian iron-formations. Eur. Miner. 1993, 5, 257–267. [Google Scholar] [CrossRef]
  48. Bau, M.; Dulski, P. Distribution of yttrium and rare-earth elements in the Penge and Kuruman iron-formations, Transvaal Supergroup, South Africa. Precambrian Res. 1996, 79, 37–55. [Google Scholar] [CrossRef]
  49. Alibo, D.S.; Nozaki, Y. Rare earth elements in seawater: Particle association, shale-normalization, and Ce oxidation. Geochim. Cosmochim. Acta 1999, 63, 363–372. [Google Scholar] [CrossRef]
  50. Tanaka, K.; Tani, Y.; Takahashi, Y.; Tanimizu, M.; Suzuki, Y.; Kozai, N.; Ohnuki, T. A specific Ce oxidation process during sorption of rare earth elements on biogenic Mn oxide produced by Acremonium sp. strain KR21-2. Geochim. Cosmochim. Acta 2010, 74, 5463–5477. [Google Scholar] [CrossRef]
  51. Ohta, A.; Kawabe, I. REE(III) adsorption onto Mn dioxide (δ-MnO2) and Fe oxyhydroxide: Ce(III) oxidation by δ-MnO2. Geochim. Cosmochim. Acta 2001, 65, 695–703. [Google Scholar] [CrossRef]
  52. Acadi, T. Rare earth element (REE)–silicic acid complexes in seawater to explain the incorporation of REEs in opal and the “leftover” REEs in surface water: New interpretation of dissolved REE distribution profiles. Geochim. Cosmochim. Acta 2013, 113, 174–192. [Google Scholar]
  53. Hathorne, E.C.; Stichel, N.; Brück, B.; Frank, M. Rare earth element distribution in the Atlantic sector of the Southern Ocean: The balance between particle scavenging and vertical supply. Mar. Chem. 2015, 177, 157–171. [Google Scholar] [CrossRef]
  54. Sholkovitz, E.R.; Landing, W.M.; Lewis, B.L. Ocean particle chemistry: The fractionation of rare earth elements between suspended particles and seawater. Geochim. Cosmochim. Acta 1994, 58, 1567–1579. [Google Scholar] [CrossRef]
  55. Hatje, V.; Schijf, J.; Johannesson, K.H.; Andrade, R.; Caetano, M.; Brito, P.; Haley, B.A.; Lagarde, M.; Jeandel, C. The global biogeochemical cycle of the rare earth elements. Glob. Biogeochem. Cycles 2024, 38, e2024GB008125. [Google Scholar] [CrossRef]
  56. Planavsky, N.; Bekker, A.; Rouxel, O.J.; Kamber, B.; Hofmann, A.; Knudsen, A.; Lyons, T.W. Rare earth element and yttrium compositions of Archean and Paleoproterozoic Fe formations revisited: New perspectives on the significance and mechanisms of deposition. Geochim. Cosmochim. Acta 2010, 74, 6387–6405. [Google Scholar] [CrossRef]
  57. Basta, F.F.; Maurice, A.E.; Fontboté, L.; Favarger, P.Y. Petrology and geochemistry of the banded iron formation (BIF) of Wadi Karim and Um Anab, Eastern Desert Egypt: Implications for the origin of Neoproterozoic BIF. Precambrian Res. 2011, 187, 277–292. [Google Scholar] [CrossRef]
  58. Hu, J.; Wang, H.; Wang, M. Geochemistry and origin of the Neoproterozoic Dahongliutan banded iron formation (BIF) in the Western Kunlun orogenic belt, Xinjiang (NW China). Ore Geol. Rev. 2017, 89, 836–857. [Google Scholar] [CrossRef]
  59. Iderbayar, B.; Oyungerel, S.; Kim, Y. Geochemistry and depositional environment of the Neoproterozoic Ereen and Dartsagt banded iron formation (BIF) deposits in the Idermeg terrane, eastern Mongolia. Geosci. J. 2024, 28, 179–192. [Google Scholar] [CrossRef]
  60. Sun, X.H.; Zhu, X.Q.; Tang, H.S.; Zhang, Q.; Luo, T.Y. The Gongchangling BIFs from the Anshan-Benxi area, NE China: Petrological-geochemical characteristics and genesis of high-grade iron ores. Ore Geol. Rev. 2014, 60, 112–125. [Google Scholar] [CrossRef]
  61. Belevtsev, Y.N.; Belevtsev, R.Y.; Siroshtan, R.I. The Krivoy Rog Basin. In Iron-Formation: Facts and Problems; Trendall, A.F., Morris, R.C., Eds.; Elsevier: Amsterdam, The Netherlands, 1982; pp. 211–252. [Google Scholar]
  62. Yin, T.T.; Jia, R.F.; Xiong, Y.Q.; Zhao, C.C. Determination of the banded iron formation sources in the Lanling area of Western Shandong of the North China Craton through rare earth element testing. Carbonates Evaporites 2024, 39, 87. [Google Scholar] [CrossRef]
  63. Chen, Y.J.; Yang, J.Q.; Deng, J.; Ji, H.Z.; Fu, S.G.; Zhou, X.P.; Lin, Q. An important change in Earth’s evolution: An environmental catastrophe at 2300 Ma and its implications. Geol. Geochem. 1996, 3, 106–128. [Google Scholar]
  64. Kato, Y.; Kawakami, T.; Kano, T.; Kunugiza, K.; Swamy, N.S. Rare-earth element geochemistry of banded iron formations and associated amphibolite from the Sargur belts, south India. J. S. Asian Earth Sci. 1996, 14, 161–164. [Google Scholar] [CrossRef]
  65. Tang, H.S.; Chen, Y.J.; Santosh, M.; Zhong, H.; Yang, T. REE geochemistry of carbonates from the Guanmenshan Formation, Liaohe Group NE Sino-Korean Craton: Implications for seawater compositional change during the Great Oxidation Event. Precambrian Res. 2013, 227, 316–336. [Google Scholar] [CrossRef]
  66. Nan, J.B.; Huang, H.; Wang, C.L.; Peng, Z.D.; Tong, X.X.; Zhang, L.C. Geochemistry and depositional setting of Banded Iron Formations in Guyang greenstone belt, Inner Mongolia. Geol. China 2017, 44, 331–345. [Google Scholar]
  67. Calvert, S.E.; Pedersen, T.F. Geochemistry of recent oxic and anoxic marine sediments: Implications for the geological record. Mar. Geol. 1993, 113, 67–88. [Google Scholar] [CrossRef]
  68. Troll, V.R.; Weis, F.A.; Jonsson, E.; Andersson, U.B.; Majidi, S.A.; Hogdahl, K.; Harris, C.; Millet, M.A.; Chinnasamy, S.S.; Kooiiman, E.; et al. Global Fe-O isotope correlation reveals magmatic origin of Kiruna-type apatite-iron-oxide ores. Nature 2019, 10, 1712. [Google Scholar] [CrossRef]
  69. Hildebrand, R.S. Kiruna-type deposits: Their origin and relationship to intermediate subvolcanic plutons in the Great Bear magmatic zone, northwest Canada. Econ. Geol. 1986, 81, 640–659. [Google Scholar] [CrossRef]
  70. González, P.D.; Sato, A.M.; Llambias, E.J. Petrology and geochemistry of the banded iron formation in the Eastern Sierras Pampeanas of San Luis (Argentina): Implications for the evolution of the Nogoli Metamorphic Complex. J. S. Am. Earth Sci. 2009, 28, 89–112. [Google Scholar] [CrossRef]
  71. Klinkhammer, G.P.; Elderfield, H.; Edmond, J.M.; Mitra, A. Geochemical implications of rare earth element patterns in hydrothermal fluids from mid-ocean ridges. Geochim. Cosmochim. Acta 1994, 58, 5105–5113. [Google Scholar] [CrossRef]
  72. German, C.R.; Klinkhammer, G.P.; Edmond, J.M.; Mura, A.; Elderfield, H. Hydrothermal scavenging of rare–earth elements in the ocean. Nature 1990, 345, 516–518. [Google Scholar] [CrossRef]
  73. Douville, E.; Charlou, J.L.; Oelkers, E.H.; Bienvenu, P.; Colon, C.F.J.; Donval, J.P.; Fouquet, Y.; Prieur, D.; Appriou, P. The rainbow vent fluids (36°14′ N, MAR): The influence of ultramafic rocks and phase separation on trace metal content in Mid-Atlantic Ridge hydrothermal fluids. Chem. Geol. 2002, 184, 37–48. [Google Scholar] [CrossRef]
  74. Danielson, A.; Moller, P.; Dulski, P. The europium anomalies in banded iron formations and the thermal history of the oceanic crust. Chem. Geol. 1992, 97, 89–100. [Google Scholar] [CrossRef]
  75. Dai, Y.P.; Zhang, L.C.; Zhu, M.T.; Wang, C.L.; Liu, L.; Xiang, P. The composition and genesis of the Mesoarchean Dagushan banded iron formation (BIF) in the Anshan area of the North China Craton. Ore Geol. Rev. 2014, 63, 353–373. [Google Scholar] [CrossRef]
  76. Klein, C. Some Precambrian banded iron-formations (BIFs) from around the world: Their age, geologic setting, mineralogy, metamorphism, geochemistry, and orgin. Am. Mineral. 2005, 90, 1473–1499. [Google Scholar] [CrossRef]
  77. Keyser, W.; Ciobanu, C.L.; Cook, N.J. Petrography and trace element signatures of iron-oxides in deposits from the Middleback Ranges, South Australia: From banded iron formation to ore. Ore Geol. Rev. 2018, 93, 337–360. [Google Scholar] [CrossRef]
  78. Wonder, J.D.; Spry, P.G.; Windom, K.E. Geochemistry and origin of manganese-rich rocks related to iron-formation and sulfide deposits, western Georgia. Econ. Geol. 1988, 83, 1070–1081. [Google Scholar] [CrossRef]
  79. Nozaki, Y.; Zhang, J.; Amakawa, H. The fractionation between Y and Ho in the marine environment. Earth Planet. Sci. Lett. 1997, 148, 329–340. [Google Scholar] [CrossRef]
  80. Bau, M.; Dulski, P. Comparing yttrium and rare earths in hydrothermal fluids from the Mid-Atlantic Ridge: Implications for Y and REE behaviour during near-vent mixing and for the Y/Ho ratio of Proterozoic seawater. Chem. Geol. 1999, 155, 77–90. [Google Scholar] [CrossRef]
  81. Alexander, B.W.; Bau, M.; Andersson, P.; Dulski, P. Continentally-derived solutes in shallow Archean seawater: Rare earth element and Nd isotope evidence in iron formation from the 2.9 Ga Pongola Supergroup, South Africa. Geochim. Cosmochim. Acta 2008, 72, 378–394. [Google Scholar] [CrossRef]
  82. Gao, X.Y.; Wang, D.H.; Huang, F.; Wang, Y.; Wang, C.H. Chronolgy and Geochemistry of the Sijiaying Iron Deposit in Eastern Hebei Province, North China Craton: Implications for the Genesis of High-Grade Iron Ores. Minerals 2023, 13, 775. [Google Scholar] [CrossRef]
  83. Han, X.; Liu, J.L. Genesis of the Neoarchean Algoma-type banded iron formation: Constraints from Fe isotope and element geochemistry of the Qian’an iron deposit, eastern North China craton. Precambrian Res. 2024, 410, 107480. [Google Scholar] [CrossRef]
  84. Holland, H.D. The Chemical Evolution of the Atmosphere and Oceans; Princeton University Press: New York, NY, USA, 1984; pp. 1–582. [Google Scholar]
  85. Bekker, A.; Holland, H.D.; Wang, P.L.; Rumble, D.; Stein, H.J.; Hannah, J.L.; Coetzee, L.L.; Beukes, N.J. Dating the rise of atmospheric oxygen. Nature 2004, 427, 117–120. [Google Scholar] [CrossRef] [PubMed]
  86. Wilde, S.A.; Zhao, G.C.; Sun, M. Development of the North China Craton during the Late Archaean and its final amalgamation at 1.8 Ga: Some speculations on its position within a global Palaeoproterozoic supercontinent. Gondwana Res. 2002, 5, 85–94. [Google Scholar] [CrossRef]
  87. Sujith, P.P.; Gonsalves, M.J.B.D. Ferromanganese oxide deposits: Geochemical and microbiological perspectives of interactions of cobalt and nickel. Ore Geol. Rev. 2021, 139, 104458. [Google Scholar] [CrossRef]
  88. Trendall, A.F.; Blockley, J.G. The iron formations of the Precambrian Hamersley Group, Western Australia with special reference to the cmcidolite. Geol. Surv. West. Aust. Bull. 1970, 119, 366. [Google Scholar]
  89. Morris, R.C. Genetic modelling for banded iron formation of the Hamersley Group, Pilbara Craton, Western Australia. Precambrian Res. 1993, 60, 243–286. [Google Scholar] [CrossRef]
  90. Webb, A.D.; Dickens, G.R.; Oliver, N.H.S. From banded iron-formation to iron ore: Geochemical and mineralogical constraints fromacrss the Hamersley Province, Western Australia. Chem. Geol. 2003, 197, 215–251. [Google Scholar] [CrossRef]
  91. Bolhar, R.; Kamber, B.S.; Moorbah, S. Characterisation of early Archaean chemical sediments by trace element signatures. Earth Planet. Sci. Lett. 2004, 222, 43–60. [Google Scholar] [CrossRef]
  92. Steinhoefel, G.; Horn, I.; Blanckenburg, F. Micro-scale tracing of Fe and Si isotope signatures in banded iron formation using femtosecond laser ablation. Geochim. Cosmochim. Acta 2009, 73, 5343–5360. [Google Scholar] [CrossRef]
Minerals 15 00996 g001
Figure 1. (a) Location map of the North China Craton in China (modified from [11]) and (b) sketch of the Precambrian geological map of the Lyuliang area in Shanxi Province (modified from [12]). 1—Cambrian strata; 2—Lanhe Group; 3—Yejishan Group; 4—Lvliang Group; 5—Jiehekou Group; 6—Chijianling–Guandishan gneiss; 7—Huijiazhuang gneissic granite; 8—Guandishan granite; 9—Gaijiazhuang gneiss; 10—Yunzhongshan gneiss; 11—Luyashan charnockite; 12—Lucaogou porphyritic granite; 13—Fault; 14—research area; 15—Anshan–Benxi area; 16—South China Sea.
Figure 1. (a) Location map of the North China Craton in China (modified from [11]) and (b) sketch of the Precambrian geological map of the Lyuliang area in Shanxi Province (modified from [12]). 1—Cambrian strata; 2—Lanhe Group; 3—Yejishan Group; 4—Lvliang Group; 5—Jiehekou Group; 6—Chijianling–Guandishan gneiss; 7—Huijiazhuang gneissic granite; 8—Guandishan granite; 9—Gaijiazhuang gneiss; 10—Yunzhongshan gneiss; 11—Luyashan charnockite; 12—Lucaogou porphyritic granite; 13—Fault; 14—research area; 15—Anshan–Benxi area; 16—South China Sea.
Minerals 15 00996 g001
Minerals 15 00996 g002
Figure 2. Stratigraphic column in the Lvliang area (modified from [13,14,15,16,17,18]).
Figure 2. Stratigraphic column in the Lvliang area (modified from [13,14,15,16,17,18]).
Minerals 15 00996 g002
Minerals 15 00996 g003aMinerals 15 00996 g003b
Figure 3. (a) Geological map of the Hugushan Iron Ore Deposit (modified from [20]). (b) Geological cross-section of the Hugushan Iron Ore Deposit (modified from [20]).
Figure 3. (a) Geological map of the Hugushan Iron Ore Deposit (modified from [20]). (b) Geological cross-section of the Hugushan Iron Ore Deposit (modified from [20]).
Minerals 15 00996 g003aMinerals 15 00996 g003b
Minerals 15 00996 g004
Figure 4. Field photos and photomicrographs of the Hugushan BIFs. (a) Field image of the quartz veins developed within the hornblende quartz magnetite. (b) Photomicrograph of gneissic hornblende quartz magnetite. (c) Photomicrograph of massive hornblende quartz magnetite. (d) Field image of the magnetite quartzite. (d) Field image of banded magnetite quartzite and chlorite schist. (e,f) Photomicrograph of banded magnetite quartzite.
Figure 4. Field photos and photomicrographs of the Hugushan BIFs. (a) Field image of the quartz veins developed within the hornblende quartz magnetite. (b) Photomicrograph of gneissic hornblende quartz magnetite. (c) Photomicrograph of massive hornblende quartz magnetite. (d) Field image of the magnetite quartzite. (d) Field image of banded magnetite quartzite and chlorite schist. (e,f) Photomicrograph of banded magnetite quartzite.
Minerals 15 00996 g004
Minerals 15 00996 g005
Figure 5. Photomicrographs of the Hugushan BIFs. (a) Photomicrograph of gneissic hornblende quartz magnetite (reflected light). (b) Photomicrograph of massive hornblende quartz magnetite (reflected light). (c) Photomicrograph of banded magnetite quartzite with quartz veinlet (cross-polarized light). (d) Photomicrograph of magnetite quartzite (cross-polarized light). Qtz—quartz; Mag—magnetite; Py—pyrite; Hbl—hornblende.
Figure 5. Photomicrographs of the Hugushan BIFs. (a) Photomicrograph of gneissic hornblende quartz magnetite (reflected light). (b) Photomicrograph of massive hornblende quartz magnetite (reflected light). (c) Photomicrograph of banded magnetite quartzite with quartz veinlet (cross-polarized light). (d) Photomicrograph of magnetite quartzite (cross-polarized light). Qtz—quartz; Mag—magnetite; Py—pyrite; Hbl—hornblende.
Minerals 15 00996 g005
Minerals 15 00996 g006
Figure 6. Major element diagrams of BIFs from the Hugushan Iron Ore Deposit. The shadow area is from [8].
Figure 6. Major element diagrams of BIFs from the Hugushan Iron Ore Deposit. The shadow area is from [8].
Minerals 15 00996 g006
Minerals 15 00996 g007
Figure 7. (a) Primitive mantle-normalized trace element spider diagram for the Hugushan BIFs (primitive mantle values from [25]); (b) PAAS-normalized REE pattern diagram of the Hugushan BIFs (PAAS values from [26]). The shadow area is from [8].
Figure 7. (a) Primitive mantle-normalized trace element spider diagram for the Hugushan BIFs (primitive mantle values from [25]); (b) PAAS-normalized REE pattern diagram of the Hugushan BIFs (PAAS values from [26]). The shadow area is from [8].
Minerals 15 00996 g007
Minerals 15 00996 g008
Figure 8. Diagrams of Fe isotope compositions for the Hugushan BIFs. The horizontal lines denote the range of variation in δ56Fe (‰). The iron isotopic compositions of materials on the Earth’s surface are from [5,27,28,29,30,31,32,33].
Figure 8. Diagrams of Fe isotope compositions for the Hugushan BIFs. The horizontal lines denote the range of variation in δ56Fe (‰). The iron isotopic compositions of materials on the Earth’s surface are from [5,27,28,29,30,31,32,33].
Minerals 15 00996 g008
Minerals 15 00996 g009
Figure 9. Diagrams of Si isotope compositions for the Hugushan BIFs. The abscissa axis denotes the range of variation in δ30Si (‰). The silicon isotopic compositions of materials on the Earth’s surface are from [5,8,34,35,36,37].
Figure 9. Diagrams of Si isotope compositions for the Hugushan BIFs. The abscissa axis denotes the range of variation in δ30Si (‰). The silicon isotopic compositions of materials on the Earth’s surface are from [5,8,34,35,36,37].
Minerals 15 00996 g009
Minerals 15 00996 g010
Figure 10. Diagrams of O isotope compositions for the Hugushan BIFs. The abscissa axis denotes the range of variation in δ18O (‰). The oxygen isotopic compositions of Yuanjiacun and Jianshan BIFs are from [8,34,38,39].
Figure 10. Diagrams of O isotope compositions for the Hugushan BIFs. The abscissa axis denotes the range of variation in δ18O (‰). The oxygen isotopic compositions of Yuanjiacun and Jianshan BIFs are from [8,34,38,39].
Minerals 15 00996 g010
Minerals 15 00996 g011
Figure 11. Ce/Ce* versus Pr/Pr* discrimination diagram (adapted from [48]).
Figure 11. Ce/Ce* versus Pr/Pr* discrimination diagram (adapted from [48]).
Minerals 15 00996 g011
Minerals 15 00996 g012
Figure 12. Diagram illustrating the origin of primary chemical precipitation based on SiO2 and Al2O3 contents [78].
Figure 12. Diagram illustrating the origin of primary chemical precipitation based on SiO2 and Al2O3 contents [78].
Minerals 15 00996 g012
Minerals 15 00996 g013
Figure 13. Elemental ratio plots with two-component conservative mixing lines for Eu/Sm and Sm/Yb (adapted from [81]). Sample symbols are the same as those in Figure 12.
Figure 13. Elemental ratio plots with two-component conservative mixing lines for Eu/Sm and Sm/Yb (adapted from [81]). Sample symbols are the same as those in Figure 12.
Minerals 15 00996 g013
Minerals 15 00996 g014
Figure 14. δ56Fe versus Ce/Ce* diagram for the Hugushan BIFs. Sample symbols are the same as those in Figure 12.
Figure 14. δ56Fe versus Ce/Ce* diagram for the Hugushan BIFs. Sample symbols are the same as those in Figure 12.
Minerals 15 00996 g014
Minerals 15 00996 g015
Figure 15. Metallogenic patterns of Hugushan BIFs.
Figure 15. Metallogenic patterns of Hugushan BIFs.
Minerals 15 00996 g015
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Wang, E.; Zhang, D.; Luan, J.; Men, Y.; Wang, R.; Xia, J.; Zhang, S. Fe–Si–O Isotope Characteristics and Ore Formation Mechanisms of the Hugushan Area BIF-Type Iron Deposits in the Central North China Craton. Minerals 2025, 15, 996. https://doi.org/10.3390/min15090996

AMA Style

Wang E, Zhang D, Luan J, Men Y, Wang R, Xia J, Zhang S. Fe–Si–O Isotope Characteristics and Ore Formation Mechanisms of the Hugushan Area BIF-Type Iron Deposits in the Central North China Craton. Minerals. 2025; 15(9):996. https://doi.org/10.3390/min15090996

Chicago/Turabian Style

Wang, Ende, Deqing Zhang, Jinpeng Luan, Yekai Men, Ran Wang, Jianming Xia, and Suibo Zhang. 2025. "Fe–Si–O Isotope Characteristics and Ore Formation Mechanisms of the Hugushan Area BIF-Type Iron Deposits in the Central North China Craton" Minerals 15, no. 9: 996. https://doi.org/10.3390/min15090996

APA Style

Wang, E., Zhang, D., Luan, J., Men, Y., Wang, R., Xia, J., & Zhang, S. (2025). Fe–Si–O Isotope Characteristics and Ore Formation Mechanisms of the Hugushan Area BIF-Type Iron Deposits in the Central North China Craton. Minerals, 15(9), 996. https://doi.org/10.3390/min15090996

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop