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Article

Geochemical Survey of Stream Sediments and Stream Water for Ion-Adsorption Type Rare Earth Deposits (IAREDs): A Pilot Study in Jiaping IARED, Guangxi, South China

by
Junhong Liu
1,
Zhixuan Han
1,2,*,
Chunfang Dong
1,*,
Xiaocheng Wei
1 and
Yingnan Chen
1
1
School of Earth Sciences, Guilin University of Technology, Guilin 541004, China
2
Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China
*
Authors to whom correspondence should be addressed.
Minerals 2025, 15(6), 642; https://doi.org/10.3390/min15060642
Submission received: 12 May 2025 / Revised: 6 June 2025 / Accepted: 11 June 2025 / Published: 13 June 2025
(This article belongs to the Special Issue Novel Methods and Applications for Mineral Exploration, Volume III)
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Abstract

:
Rare earth elements (REEs) are critical mineral resources that play a pivotal role in modern technology and industry. Currently, the global supply of light rare earth elements (LREEs) remains adequate. However, the supply of heavy rare earth elements (HREEs) is associated with substantial risks due to their limited availability. Ion-adsorption type rare earth deposits (IAREDs), which represent the predominant source of HREEs, have become a focal point for exploration activities, with a notable increase in global interest in recent years. This study systematically collected stream sediments and stream water samples from the Jiaping IARED in Guangxi, as well as from adjacent granitic and carbonate background areas, to investigate the exploration significance of geochemical surveys for IAREDs. Additionally, mineralized soil layers, non-mineralized soil layers, and bedrock samples from the weathering crust of the Jiaping deposit were analyzed. The results indicate that stream sediments originating from the Jiaping IARED and granite-hosted background regions display substantially elevated REE concentrations relative to those from carbonate-hosted background areas. Moreover, δEu values in stream sediments can serve as an effective indicator for differentiating weathering products derived from granitic and carbonate lithologies. Within the mining area, three coarse-grained fractions of stream sediments (i.e., +20 mesh, 20–60 mesh, and 60–150 mesh) exhibit REE concentrations comparable to those observed in both granite-hosted and carbonate-hosted background regions. However, the HREEs content in the finer -150-mesh stream sediments from Jiaping IARED is markedly higher than that in the two background regions. The (La/Sm)N versus (La/Yb)N ratios of -150-mesh stream sediments in the Jiaping IARED may reflect the mixing processes involving HREE-enriched ore layer, non-mineralized layer, and LREE-enriched ore layer. This observation implies that fine-grained (-150-mesh) stream sediments can partially inherit the REE characteristics of mineralized layers within IAREDs. Scanning electron microscopy (SEM) observations indicate that the enrichment of REEs in fine-grained stream sediments primarily originates from REE-rich accessory minerals derived from parent rocks and mineralized weathering crusts. A comparative analysis reveals that the concentrations of REEs in stream water collected during the rainy season are significantly higher than those collected during the dry season. Moreover, the levels of REEs, especially HREE, in stream water from the Jiaping IARED substantially exceed those in background areas. Collectively, these findings suggest that the geochemical signatures of REEs in rainy season stream water possess diagnostic potential for identifying IAREDs. In conclusion, the integrated application of geochemical surveys of stream water and -150-mesh stream sediments can effectively delineate exploration targets for IAREDs.

1. Introduction

Rare earth elements (REEs) exhibit exceptional optical, electrical, and magnetic properties [1,2,3]. These elements are extensively utilized in high-tech industries and are recognized as strategic critical mineral resources [4,5,6]. Based on atomic number, REE are categorized into LREEs and HREEs. Currently, LREE resources predominantly originate from carbonatite–alkaline rock-related deposits [7], while HREEs are primarily extracted from ion-adsorption type rare earth deposits (IAREDs) [8].
IAREDs account for more than 70% of the global HREE reserves and supply 90% of the global HREE production [9,10]. These deposits predominantly form in granite weathering crusts through the activation, migration, and re-enrichment of REE during the weathering and leaching of REE-enriched parent rocks [11]. They are characterized by large-scale mineralization, widespread distribution, and relatively straightforward extraction processes [12]. The seven provinces in southern China represent the world’s most significant ion-adsorption REE metallogenic province. Recent discoveries of similar deposits in Southeast Asia, the Americas, and Africa [6,13,14,15,16,17] have sparked a global exploration surge. However, current exploration methodologies remain constrained, primarily relying on geological and remote sensing-based target selection [18], followed by shallow drilling verification (commonly referred to as the “Gannan driller”) [19]. Despite the proposal of numerous prospecting indicators [20], there is still an urgent need for rapid and effective target delineation techniques.
Low-density stream sediment geochemical surveys have been demonstrated to be effective for mineral exploration [21,22]. This methodology has been successfully implemented, showing high feasibility and superior accuracy compared to alternative methods by comprehensively capturing mineralogical data, thereby providing both technical and theoretical foundations for delineating exploration target areas [23]. However, its success has predominantly been observed in exposed or semi-exposed deposits with high metallogenic concentration coefficients, such as precious metals (e.g., Au) and base metals (e.g., Cu, Pb, Zn) [24,25,26]. The applicability of stream sediment surveys to IAREDs—which exhibit low mineralization concentration coefficients [27]—remains uncertain. Our preliminary investigations indicate that over 80% of IAREDs exhibit characteristic geochemical signatures [28]. Moreover, stream sediment surveys have successfully identified promising exploration areas in Yunnan Province [29,30]. Nevertheless, La-Y anomalies in stream sediments from the Pubei pluton failed to detect IARED mineralization [28], highlighting the necessity for further research into optimal sediment grain sizes and diagnostic element combinations.
Water functions as a universal medium in geochemical exploration, where hydrogeochemical surveys facilitate rapid, large-scale evaluations of ore potential and the detection of concealed deposits [31]. As a complementary approach to traditional geochemical methods [32], hydrogeochemical measurements exhibit comparable efficacy in identifying mineralized zones and provide significant practical value [33]. Descending groundwater acts as the ore-forming fluid in ion-adsorption REE systems, retaining critical metallogenic information [34]. The groundwater may transport mineralization signals into river systems, and the stream water can preserve mineralization information from IAREDs [35,36]. Consequently, stream water geochemistry merits further investigation as a promising exploration indicator.
Guangxi Province hosts extensive intermediate-acidic magmatic rocks [37]. Intense weathering under warm–humid subtropical conditions has developed thick weathering crust favorable for ion-adsorption REE formation. The Jiaping deposit—a medium-sized IARED newly discovered in Lingshan County, Qinzhou City [38,39]—provides an ideal study area with well-developed drainage systems that is free of anthropogenic contamination from illegal mining activities.
This study systematically analyzed the REE characteristics of stream water and stream sediments with multiple grain sizes collected from the Jiaping IARED and non-mineralized background areas (granite and carbonate rocks) to evaluate the efficacy of geochemical surveys for detecting IAREDs mineralization.

2. Regional Geological Background

The study area is located in the Dalongshan Granite Belt (Figure 1), which is situated in the southeastern Guangxi [40]. This granite belt extends approximately 400 km in length and varies between 20 and 75 km in width, covering an area of approximately 10,000 km2 with a NE-SW orientation [41]. Under intense compression caused by the subduction of the Indian Ocean Plate, multiple plutons were placed and uplifted. The resulting nappe tectonics led to significant crustal thickening, which in turn triggered crustal anatexis or dehydration melting during orogenic uplift. This process melted metasedimentary rocks within the crust, generating granitic magmas and ultimately forming S-type granites [42]. From the Early Paleozoic to Early Mesozoic period, this region experienced a complex tectonic–magmatic evolution, culminating in the formation of a typical S-type granite suite in South China [43]. Within this belt, the Taima, Jiuzhou, Pubei, and Darongshan granitic plutons are distributed from west to east. Notably, the Jiaping IARED (45 km2) comprises granitic rocks of the NE-trending Jiuzhou Pluton, which occur as elongated lenticular bodies parallel to regional faults and intrude into Paleozoic strata. The exposed stratigraphic sequence includes Sinian metamorphic conglomerates, shales, and carbonates; Cambrian siliceous rocks, carbonaceous siliceous shales, and limestones; Ordovician calcareous shales, black shales, and nodular limestones; carboniferous quartz conglomerates, limestones, and dolomites; Triassic siltstones, mudstones interbedded with quartz sandstones, carbonaceous mudstones, and coal seams; Jurassic feldspathic quartz sandstones, polymictic conglomerates, and lithic graywackes; Cretaceous sandstones, siltstones, mudstones, and polymictic conglomerates; and Quaternary clays, subclays, and gravel layers.
These Indosinian biotite monzogranites intrude into the Silurian, Devonian, and Upper Permian stratums [44], showing distinct REE fractionation with LREE enrichment and pronounced negative Eu anomalies. Geochemically, they are characterized by a low quantity of silica, peraluminous composition, and phosphorus enrichment, exhibiting a “right-leaning” chondrite-normalized REE pattern. Mineralogically, these rocks consist of plagioclase, K-feldspar, quartz, biotite, cordierite, muscovite, hypersthene, and almandine, forming a high-K calc-alkaline series with weakly to strongly peraluminous features [45].
Minerals 15 00642 g001
Figure 1. Regional geological sketch map of southeastern Guangxi (modified after reference [46]).
Figure 1. Regional geological sketch map of southeastern Guangxi (modified after reference [46]).
Minerals 15 00642 g001

3. Sample Collection and Analysis

3.1. Sample Collection

(1)
Collection of sediment and water samples
Stream water and stream sediment samples were systematically collected from 19 locations in Lingshan County, Guangxi. These included 15 sampling points within the Jiaping IARED, 2 points from the granite background area, and 2 points from the carbonate background area (Figure 2). In accordance with standardized hydrological protocols, water samples were collected at depths ranging from 0.5 m below the water surface to 0.5 m above the riverbed. For shallow streams (<1 m depth), mid-depth sampling was performed. Sampling sites were strategically selected in optically transparent river sections characterized by laminar flow regimes, while avoiding areas influenced by hydraulic anomalies or anthropogenic disturbances. Prior to collection, all sampling containers were rigorously sterilized through a 24 h aqua regia immersion followed by triple rinsing with deionized water. Additionally, immediate pre-rinsing with site-specific water was conducted just before sampling.
Post-collection processing commenced with the removal of macroscopic debris via filtration using a 2 mm nylon mesh. Suspended particulates were subsequently isolated through vacuum-assisted filtration employing an all-glass microporous membrane filtration assembly (0.45 μm cellulose acetate membranes). Membrane preconditioning was conducted by rinsing with deionized water and ensuring precise alignment within Buchner funnels. Prior to each filtration cycle, system integrity was verified, and samples were homogenized rigorously to prevent particulate sedimentation. For REEs analysis, 200 mL aliquots of filtered water were preserved in nitric acid-passivated high-density polyethylene (HDPE) bottles, acidified with 5 mL of 1:1 HCl, vortexed thoroughly, and transported under cold-chain conditions (4 °C) with comprehensive chain-of-custody documentation.
(2)
Weathered crust soil and bedrock sampling in Jiaping IARED
With “Gannan Driller” (a specialized percussion drilling system for IAREDs), a total of 54 samples were collected, including 13 heavy rare earth-enriched layers (LREE/HREE < 1), 26 light rare earth-dominated layers (LREE/HREE > 1), and 15 non-mineralized layers (topsoil horizons). Additionally, five bedrock samples (coarse-grained biotite monzogranite) were collected.

3.2. Sample Pretreatment

(1)
Stream Water
Given the ultra-trace concentrations of REEs in aqueous systems, a pre-concentration protocol was implemented using evaporation-based enrichment. For each 100 mL aliquot, sequential evaporation cycles were conducted: initial evaporation to dryness at 85 °C, followed by a deionized water rinse of container walls, secondary evaporation, and final dissolution in 5–10 mL 2% HNO3 under 100 °C heating for 10 min. Reconstituted solutions were diluted to 10 mL with 2% HNO2 for instrumental analysis.
(2)
Stream Sediments
Samples were divided into archival and analytical sections, with the analytical portions subjected to granulometric separation via a series of stacked sieves (+20, 20–60, 60–150, and -150 mesh). The resulting sieved fractions were subsequently pulverized to a consistency of -200 mesh using agate mills and stored in anti-static polyethylene bags for further analysis.
(3)
Weathered Crust Soils
Air-dried samples (200 g) were homogenized through planetary ball milling (<200 mesh particle size) and preserved in anti-static polyethylene bags.
(4)
Bedrocks
Mechanically cleaned rock fragments (with dimensions ≤ 1 cm) were subjected to ultrasonic cleaning using deionized water, followed by oven drying at 105 °C and subsequent comminution to a particle size of -200 mesh using tungsten carbide crushers. Contamination controls were rigorously enforced through the use of quartz sand blanks during the grinding process.

3.3. Chemical Analysis

(1)
Chemical analysis of REEs
Quantitative analysis of REEs was performed using an Agilent 700 series inductively coupled plasma mass spectrometer (ICP-MS) (Agilent Technologies Co Ltd, the United States). The procedure entailed precisely weighing 100 mg of dried powdered sample into a digestion vessel, followed by the sequential addition of 1 mL of HNO3 and 1 mL of HF. The mixture was subsequently heated at 190 °C for 48 h in a sealed oven, cooled to room temperature, and then evaporated to dryness at 165 °C. Thereafter, 1 mL of HNO3 was added, and the evaporation–heating cycle was repeated twice at 150 °C for 5 h each. Following cooling, the residue was diluted to a final volume of 100 mL with deionized water for instrumental analysis. Quality control measures included the parallel analysis of national certified reference materials and laboratory duplicates, ensuring total analytical errors were within ±6% (1σ) for all REEs.
(2)
Analysis of major elements for stream sediments
Major elements were analyzed using an X-ray fluorescence spectrometer (Rigaku Corporation, Japan) with analytical precision better than 1%.
(3)
Scanning Electron Microscopy Analysis
A fraction sample (-150 mesh) of JPS15 was securely mounted on a glass slide using an epoxy-based conductive adhesive. Subsequently, the sample was coated with carbon to improve its electrical conductivity. Morphological and compositional analyses of soil mineral particles were performed using a Zeiss field-emission scanning electron microscope (FE-SEM) integrated with an X-ray energy-dispersive spectrometer (EDS) (Carl Zeiss AG, Germany). The EDS system featured a resolution of 1.3 nm, adjustable acceleration voltages ranging from 0.1 to 30 kV, probe currents varying between 4 pA and 20 nA, and a maximum magnification of 1,000,000×. The analytical error associated with these measurements was approximately 3%.

4. Results

4.1. REE Characteristics of Stream Sediments

Table 1 illustrates the REE concentrations across various particle size fractions of stream sediments from the Jiaping IARED and background regions, highlighting distinct geochemical differences existing in these three regions. Both the mining area and background areas exhibit the highest total REE concentrations in the -150-mesh fraction. In coarser fractions (60–150, 20–60, and +20 mesh), the Jiaping IARED demonstrates lower average REE concentrations compared to the granitic background area but comparable REE levels to the carbonate bedrock background zone. Notably, the -150-mesh fraction in Jiaping shows slightly higher REE content than the granitic background and significantly elevated levels relative to the carbonate background. While all fractions displayed LREE enrichment (LREE/HREE > 1), the Jiaping sediments exhibited higher HREE contributions, as evidenced by the lower LREE/HREE ratios compared to both granitic and carbonate backgrounds. The δEu values of stream sediments across different grain sizes in various regions are all negative, with the δEu of the -150-mesh fraction being smaller than those of the other three grain sizes. The δEu in the rare earth mining area is comparable to that in the granitic background area and significantly lower than that in the carbonate rock background area. Additionally, the δCe in the carbonate rock background area is lower than that in the granite background area and the Jiaping IARED.

4.2. Geochemical Characteristics of Dissolved REE in Stream Water

In the stream water samples collected from the Jiaping IARED area, the ΣREE values ranged from 0.25 to 4.03 ng/mL, with an average concentration of 1.64 ng/mL (Table 2). This value was higher than that observed in the granite background area (1.13 ng/mL) and the carbonate rock background area (0.76 ng/mL). The LREE/HREE ratio in the stream water of the mining area, averaging 1.78, was lower than the ratios of 3.64 and 2.54 observed in the background areas, suggesting a relatively higher enrichment of HREEs in the mining area’s stream water. Additionally, δEu and δCe values exhibited significant variability in the stream waters. In the mining area, δEu values ranged from 0.80 to 6.33 (average: 1.72), while δCe values ranged from 0.28 to 1.24 (average: 0.88). No clear patterns were observed in the δEu and δCe values between the mining and background areas, potentially attributable to the substantial variations in these parameters under hydrodynamic conditions.

4.3. REE Characteristics of Crust Soils and Bedrocks in Jiaping IARED Area

The REE contents of the weathered crust soils and bedrocks in the mining area are presented in Table 3. The results indicate that the REE content, ranked from highest to lowest, adheres to the following order: HREE mineralized layer (average 1365.00 μg/g) > LREE mineralized layer (average 1146.15 μg/g) > unmineralized layer (average 322.34 μg/g) > bedrock (average 257.44 μg/g). The variation characteristics of HREE content exhibit a similar trend, with the following sequence: HREE mineralized layer (average 820.44 μg/g) > LREE mineralized layer (average 332.07 μg/g) > bedrock (average 68.25 μg/g) > unmineralized layer (average 50.16 μg/g). The LREE content, in descending order, is manifested as follows: LREE mineralized layer (average 814.08 μg/g) > HREE mineralized layer (average 544.60 μg/g) > unmineralized layer (average 272.17 μg/g) > bedrock (average 189.19 μg/g). The HREE ore layer is enriched in HREEs, with the LREE/HREE ratio being less than 1. In contrast, the remaining samples are enriched in LREEs, and the LREE/HREE ratios in the unmineralized layer are significantly higher than those in the mineralized layers. The δCe values in the unmineralized layer show a pronounced positive anomaly. Both the LREE and HREE mineralized layer samples exhibit notable negative δCe anomalies, whereas the δEu anomalies are not prominent.

4.4. Mineralogical Characteristics of -150-Mesh Stream Sediments in Jiaping Area

Figure 3 illustrates the SEM analysis results of the -150-mesh stream sediments collected from the Jiaping IARED. The results reveal a significant abundance of clay minerals and rare earth element (REE)-rich minerals, including zircon, monazite, xenotime, and cerianite, as well as ilmenite. Clay minerals exhibit a wide range of grain sizes, varying from several micrometers to hundreds of micrometers. Larger particles display intact book-like morphologies, such as kaolinite, as shown in Figure 3d, while smaller fragments appear as detrital grains dispersed throughout the sediment matrix (Figure 3e,f). Some clay minerals irregularly coat the surfaces of zircon and ilmenite (Figure 3a,b). Two distinct types of zircon are identified: larger grains measuring approximately 100 μm in length with subhedral to euhedral prismatic shapes, partially coated by clay minerals (Figure 3a), and smaller columnar grains measuring approximately 30 μm in length embedded within clay aggregates (Figure 3b). Xenotime is observed as particles ranging from 15 to 25 μm in size, either embedded in clay matrices (Figure 3d) or occurring as subhedral short prisms (Figure 3e). Monazite (approximately 15 μm) and cerianite (approximately 5 μm) are present as irregular independent grains within the sediment (Figure 3c,f).

5. Discussion

5.1. Geochemical Characteristics of Dissolved REE in Stream Water and Their Indicative Significance for IAREDs

5.1.1. Dissolved REE Variation in Stream Water in Dry and Rainy Season

REE content in stream water exhibits significant variation across different sampling periods. To investigate the variation patterns of dissolved REE in stream water within the mining area, sampling was performed at the same location in Jiaping IARED during both the rainy and dry seasons to establish a control group. The sampling periods corresponded to the dry and rainy seasons of the same year. As shown in Figure 4, the distribution curves of rare earth elements in stream water during both the dry and rainy seasons exhibit similarity, with both being right-skewed. This indicates that the sources of REE in stream water are homologous between the two seasons. However, compared to samples collected during the dry season, stream water samples from the rainy season demonstrate higher REE concentrations. While seasonal differences do not substantially alter rare earth fractionation, the increased runoff during the rainy season enhances the leaching effect on the surface weathering crust, thereby increasing the release of ionic REE. Furthermore, significant differences in δEu and δCe values between the dry and rainy seasons suggest that fluid flow may play a critical role as an influencing factor in the migration process of REE.

5.1.2. Indicative Significance of Dissolved REE in Stream Water for IAREDs

As shown in Figure 5, the chondrite-normalized REE distributions in the stream water of the mining area and the background area are similar. This demonstrates that the LREEs concentrations in stream waters within the mining area and the granite background region are higher than that in the carbonate rock background region. This suggests that the LREE content in stream water associated with the granite background is elevated, indicating an inheritance of REE characteristics from the parent rock. Meanwhile, the HREE concentrations in the mining area are observed to be higher than those in both the granite and carbonate rock background regions. The elevated HREE content in the stream water of the mining area may originate from the HREE ore layers within the weathering crust ore body. These findings indicate that the geochemical characteristics of REEs in the stream water of Jiaping IARED and the background areas exhibit distinct differences.
The scatter plot of (La/Yb)N-(La/Sm)N was further utilized to examine the relationships between stream waters and LREE/HREE mineralized layers, unmineralized layers, and bedrocks (see Figure 6). This analysis facilitates the discrimination of dissolved REE sources in stream waters based on their distribution patterns. The (La/Yb)N ratios in stream waters are slightly higher than those in HREE-enriched layers but significantly lower than values in LREE-enriched layers, unmineralized layers, and bedrocks. Similarly, (La/Sm)N ratios of stream waters slightly exceed that of HREE layers and are lower than that of LREE layers, unmineralized layers, and bedrocks. These findings indicate that the dissolved REE in stream waters originate from a mixed source comprising HREE/LREE mineralized layers, unmineralized layers, and bedrocks, rather than being attributed solely to contributions from bedrocks or unmineralized layers. Stream water in the mining area can inherit the geochemical REE signatures from both parent rocks and weathering crust ore bodies. Therefore, the geochemical survey of stream waters may potentially serve as an effective tool for the exploration of IAREDs.

5.2. Geochemical Signatures of Stream Sediments and Their Indicative Significance for IAREDs

5.2.1. Distribution Characteristics of REE in Stream Sediments of Different Grain Sizes in the Mining Area and the Background Area

Figure 7 depicts the REE distribution patterns across particle size fractions of sediments from the Jiaping IARED and background areas. Coarser fractions (+20, 20–60, and 60–150-mesh) exhibit comparable REE concentrations and fractionation trends in both the mining area and background regions. Notably, some Jiaping sediments display lower REE levels than those of the granitic background area. Distinct geochemical variations are evident in the -150-mesh stream sediments across the three regions, with significantly higher REE concentrations observed in the granitic background and mining areas compared to the carbonate background zone. While LREE contents in Jiaping’s -150-mesh sediments align with those of the Pubei granitic background, their HREE concentrations are markedly elevated. The stream sediments in Jiaping IARED exhibit co-enrichment of LREE and HREE, with notably higher HREE levels relative to the background areas, suggesting that the -150-mesh sediments partially inherit the REE characteristics of the HREE ore layers. Consequently, -150-mesh stream sediments represent the optimal sampling medium for detecting IAREDs mineralization.

5.2.2. The REE Enrichment Mechanism of Fine-Grained (-150-Mesh) Stream Sediments

Elucidating the occurrence forms of REEs in stream sediments is essential for understanding their enrichment mechanisms. Studies have demonstrated a significant correlation between clay minerals and REE enrichment in sediments [47,48]. The Si/Al ratio has been established as an effective proxy for clay mineral content, with lower Si/Al values indicating higher abundances of clay minerals [49,50]. As depicted in Figure 8, both LREE and HREE exhibit strong negative correlations with the Si/Al ratio. Additionally, clay mineral content increases as the particle size decreases. Prior research has shown that the acid-soluble REE fraction in sediments derived from granitic weathering typically exceeds 20% [51], predominantly adsorbed onto clay minerals. The unique interlayer structures, high specific surface area, and low point of zero charge of clay minerals enhance their capacity to adsorb REEs, which becomes more pronounced with smaller particle sizes due to the increased surface area [52]. In IAREDs, REEs primarily exist in adsorbed forms associated with clay minerals [53]. Consequently, REEs released from mineralized weathering crusts may migrate through leaching as ions or colloids and subsequently be captured by fine-grained clay minerals in sediments.
Discrete rare earth minerals constitute a critical host phase for REE in sediments [54]. Figure 8 demonstrates statistically significant positive correlations between REE concentrations and P and Zr levels, with finer-grained samples exhibiting markedly higher P, Zr, and REE content. In the mineralized granite of the Jiaping IARED, monazite, xenotime, and zircon—key accessory minerals rich in REE [55,56]—are present as fine-grained particles (<50 μm) [39,40], which aligns with our SEM observations (Figure 3). These fine-grained REE-bearing minerals display robust resistance to weathering processes [57], remaining largely intact during parent rock weathering and subsequently being transported into stream sediments, thereby contributing to REE enrichment in the fine-grained sedimentary fractions.

5.2.3. Indicative Significance of Stream Sediment Survey for IAREDs

The efficacy of utilizing stream sediments for identifying ore bodies hinges on the existence of distinct geochemical contrasts between mining-impacted and background regions. REE signatures across various particle size fractions serve as reliable tracers for determining material provenance [58,59]. As evidenced by prior research [20,60], significant variations in REE concentrations and fractionation patterns among sediment grain sizes offer crucial discriminative indicators for mineralization detection.
δEu and δCe in sediments are widely utilized as provenance tracers [61,62]. However, the oxidation of Ce3+ to Ce4+; during weathering processes [63,64] can result in positive δCe anomalies in sediments derived from diverse parent rocks [65,66], thereby complicating source discrimination based solely on δCe values [28]. Under oxidizing supergene weathering conditions, δEu typically remains stable and retains characteristics inherited from the source rocks [28]. Generally, sediments originating from weathered granites exhibit pronounced negative δEu anomalies, whereas those from carbonate rocks display weaker negative δEu anomalies [67]. This study corroborates previous findings: δEu values in sediments from the Jiaping IARED and granitic backgrounds are substantially lower than those from carbonate backgrounds (see Table 1), reaching their minima in the -150-mesh fraction (Figure 9). Nevertheless, the similarity in δEu values between Jiaping and granitic backgrounds diminishes the effectiveness of δEu and δCe in distinguishing mineralized from non-mineralized granitic zones, although they remain effective in differentiating granitic and carbonate terrains.
The fractionation patterns of REEs in stream sediments are closely associated with their parent rocks [68]. To investigate the genetic relationships between -150-mesh sediments from the mining area and mineralized weathering crusts, the ratios of (La/Sm)N and (La/Yb)N, which are commonly used to quantify REE fractionation degrees, were analyzed (Figure 10). Scatter plots demonstrate that -150-mesh sediments and bedrock and LREE ore layer exhibit similar distribution trends, indicating the inheritance of parental REE signatures. The partial overlap of (La/Sm)N and (La/Yb)N ratios between -150-mesh sediments and topsoil horizons suggests that under high-energy hydrodynamic conditions, topsoil materials are preferentially eroded and transported into stream systems. While the (La/Yb)N ratios of -150-mesh sediments align with layers enriched in light rare earth elements (LREEs), their (La/Sm)N values generally exceed those of LREE horizons. Layers dominated by HREEs display significantly lower (La/Yb)N ratios compared to bedrock, topsoil, and LREE layers. Although -150-mesh sediments exhibit higher (La/Yb)N ratios than HREE horizons, partial overlap indicates residual inheritance of HREE mineralization signatures. Collectively, the REE characteristics, including HREE and δEu anomalies in -150-mesh stream sediments, serve as effective indicators for identifying IAREDs.

6. Conclusions

This study examined the efficacy of stream sediment and water geochemistry survey in identifying IAREDs through systematic surveys conducted in the Jiaping IARED and adjacent granitic and carbonate bedrock background regions. The results demonstrated significantly higher REE concentrations in stream water during the rainy season compared to the dry season, with elevated REE levels observed in stream waters within the mining area relative to background zones. These findings underscore the utility of hydro-geochemical anomalies for delineating IAREDs mineralization. While coarser sediment fractions (-20, 20–60, and 60–150-mesh) exhibited minimal geochemical differences between mining and background areas, the -150-mesh fraction provided diagnostic indicators, including LREE/HREE ratios and HREE enrichment, for effective mineralization detection. An integrated analysis of stream water and -150-mesh sediment geochemical survey proved to be a robust approach for targeting granitic IAREDs, thereby advancing the exploration of geochemical methodologies and providing technical support for prospecting analogous deposits.

Author Contributions

Conceptualization, Z.H. and J.L.; methodology, Z.H. and C.D.; software, J.L. and X.W.; validation, J.L., C.D. and Y.C.; formal analysis, J.L.; investigation, X.W., C.D. and Z.H.; resources, Z.H.; data curation, J.L. and C.D.; writing—original draft preparation, J.L. and C.D.; writing—review and editing, Z.H.; visualization, X.W. and J.L.; supervision, Z.H.; project administration, Z.H.; funding acquisition, Z.H. All authors have read and agreed to the published version of the manuscript.

Funding

This study was fund by National Key Research and Development Program of China (2024YFC2909904), Guangxi Natural Science Foundation (GuikeAD23026129), National Natural Science Foundation of China (42263011), National Nonprofit Institute Research Grant of CAGS (JKYQN202414).

Data Availability Statement

Data will be made available on request.

Acknowledgments

Many thanks are given to all participants in the project for their hard work in sample preparation, laboratory analysis and data processing. Comments from three anonymous reviewers helped a lot to improve the paper.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Liu, R.H. Applications and Prospects of Rare Earth Magnetic Materials. Nonferrous Met. Eng. 2002, 01, 60–61, (In Chinese with English Abstract). [Google Scholar]
  2. Song, X.; Chang, M.H.; Pecht, M. Rare-earth elements in lighting and optical applications and their recycling. Jom 2013, 65, 1276–1282. [Google Scholar] [CrossRef]
  3. Chakhmouradian, A.; Wall, F. Rare earth elements: Minerals, mines, magnets (and more). Elements 2012, 8, 333–340. [Google Scholar] [CrossRef]
  4. Huang, X.W.; Li, H.W.; Wang, C.F.; Wang, G.Z.; Xue, X.X.; Zhang, G.C. Development Status and Research Progress in Rare Earth Industry in China. China. J. Rare Met. 2007, 03, 279–288, (In Chinese with English Abstract). [Google Scholar]
  5. Malavekar, D.B.; Magdum, V.V.; Khot, S.D.; Kim, J.H.; Lokhande, C.D. Doping of rare earth elements: Towards enhancing the electrochemical performance of pseudocapacitive materials. J. Alloys Compd. 2023, 960, 170601. [Google Scholar] [CrossRef]
  6. Liu, S.L.; Fan, H.R.; Liu, X.; Meng, J.; Butcher, A.R.; Yann, L.; Yang, K.F.; Li, X.C. Global rare earth elements projects: New developments and supply chains. Ore Geol. Rev. 2023, 157, 105428. [Google Scholar] [CrossRef]
  7. Mao, J.W.; Song, S.W.; Liu, M.; Meng, J.Y. REE deposits: Basic characteristics and global metallogeny. Acta Geol. Sin. 2022, 96, 3675–3697, (In Chinese with English Abstract). [Google Scholar]
  8. Li, M.Y.H.; Zhou, M.F.; Williams-jones, E.A. The genesis of regolith-hosted heavy rare earth element deposits: Insights from the world-class Zudong deposit in Jiangxi Province, South China. Econ. Geol. 2019, 114, 541–568. [Google Scholar] [CrossRef]
  9. Wang, D.H.; Zhao, Z.; Yu, Y.; Wang, C.H.; Dai, J.J.; Sun, Y.; Zhao, D.; Li, J.K.; Huang, F.; Chen, Z.Y.; et al. A review of the achievements in the survey and study of Ion-absorption type REE deposits in China. Acta Geoscientica Sinica 2017, 38, 317–325, (In Chinese with English Abstract). [Google Scholar]
  10. He, H.P.; Wang, Y.; Li, X.R.; Ma, L.Y.; Zhu, J.X.; Yang, W.B. Remobilization and transferring of rare earth elements in the formation of regolith-hosted REE deposits. J. Geomech. 2024, 30, 707–722, (In Chinese with English Abstract). [Google Scholar]
  11. Dong, C.F. Research Progress on the Enrichment and Differentiation Mechanism of Rare Earth Elements During Granite Weathering. Acta Geologica Sichuan 2024, 44, 3–6, (In Chinese with English Abstract). [Google Scholar]
  12. Chi, R.A.; Tian, J. Review of Weathered Crust Rare Earth Ore. J. Rare Earths 2007, 06, 641–650, (In Chinese with English Abstract). [Google Scholar]
  13. Padrones, J.T.; Imai, A.; Takahashi, R. Geochemical behavior of rare earth elements in weathered granitic rocks in northern Palawan, Philippines. Resour. Geol. 2017, 67, 231–253. [Google Scholar] [CrossRef]
  14. Ram, R.; Becker, M.; Brugger, J.; Etschmann, B.; Burcher-jones, C.; Howard, D.; Kooyman, P.J.; Petersen, J. Characterisation of a rare earth element-and zirconium-bearing ion-adsorption clay deposit in Madagascar. Chem. Geol. 2019, 522, 93–107. [Google Scholar] [CrossRef]
  15. Borst, A.M.; Smith, M.P.; Finch, A.A.; Estrade, G.; Villanova-de-benavent, C.; Nason, P.; Marquis, E.; Horsburgh, N.J.; Goodenough, K.M.; Xu, C. Adsorption of rare earth elements in regolith-hosted clay deposits. Nat. Commun. 2020, 11, 4386. [Google Scholar] [CrossRef]
  16. Santana, I.V.; Botelho, N.F. REE residence, behaviour and recovery from a weathering profile related to the Serra Dourada Granite, Goiás/Tocantins States, Brazil. Ore Geol. Rev. 2022, 143, 104751. [Google Scholar] [CrossRef]
  17. Gibaga, C.R.L.; Samaniego, J.O.; Tanciongco, A.M.; Quierrez, R.N.M.; Montano, M.O.; Gervasio, J.H.C.; Reyes, R.C.G.; Peralta, M.J.V. The rare earth element (REE) potential of the Philippines. J. Geochem. Explor. 2022, 242, 107082. [Google Scholar] [CrossRef]
  18. Liu, X.X.; Meng, M.M.; Zhao, Z.; Wang, N.; Huang, F.; Zhang, B.; Yang, X.F. Review of Remote Sensing Technology Application in Rare-Earth Mining. J. Rare Earths 2015, 33, 524–534, (In Chinese with English Abstract). [Google Scholar]
  19. Zeng, Z.L.; Liang, J.S.; Wu, B.; Li, X.H.; Zhou, X.Y. Application of Gannan Drill in Rare Earth Ore Prospecting. Explor. Eng. (Rock Soil Drill. Tunneling) 2016, 43, 44–47, (In Chinese with English Abstract). [Google Scholar]
  20. Luo, X.; Zhang, Y.; Zhou, H.; He, K.; Luo, C.; Liu, Z.; Tang, X. Review on the development and utilization of ionic rare earth ore. Minerals 2022, 12, 554. [Google Scholar] [CrossRef]
  21. Xie, X.J. New strategy for exploration of ore resources. J. Geophys. Geochem. Explor. 1997, 06, 402–410, (In Chinese with English Abstract). [Google Scholar]
  22. Xie, X.J.; Cheng, H.X. Sixty years of exploration geochemistry in China. J. Geochem. Explor. 2014, 139, 4–8. [Google Scholar] [CrossRef]
  23. Song, S.R. Analysis of geochemical characteristics and prospecting direction of stream sediment survey. World Nonferrous Met. 2018, 05, 101–102, (In Chinese with English Abstract). [Google Scholar]
  24. Li, H.; Zhang, G.Y.; Yu, B.; Li, D.L. The 20THC century’s 10 new achievements in the metallurgical geology field. Contrib. Geol. Miner. Resour. Res. 2006, S1, 125–130, (In Chinese with English Abstract). [Google Scholar]
  25. Wang, J.; Zhu, L.X.; Ma, S.M.; Tan, S.X.; Zhang, L.L.; Zhou, W.W. Application of the multi-attribute anomaly model for prospecting potential at depth: A case study of the Haiyu Au deposit in the Jiaodong Gold Province, China. J. Geochem. Explor. 2019, 207, 106359. [Google Scholar]
  26. Yaseen, I.B. Geochemical Exploration for Gold and the Association of As-Cu-Pb-Sn-Zn-Li in the Upper Proterozoic Granitoids of the Wadi Rumman Area, Southwest Jordan. Int. J. Geosci. 2015, 6, 1140–1153. [Google Scholar] [CrossRef]
  27. Chi, R.A.; Tian, J.; Luo, X.P.; Xu, Z.G.; He, Z.Y. The basic research on the weathered crust elution-deposited rare earth ores. Nonferrous Met. Sci. Eng. 2012, 3, 1–13, (In Chinese with English Abstract). [Google Scholar]
  28. Han, Z.X.; Lu, H.T.; Zhang, B.M.; Cheng, Z.Z.; Fu, W.; Lao, C.L.; Xu, C. Delineating preliminary prospective areas of IAREDs with stream sediments geochemical mapping in South China. J. Asian Earth Sci. 2023, 243, 105520. [Google Scholar] [CrossRef]
  29. Wang, W.; Wang, X.Q.; Zhang, B.M.; Wang, Q.; Liu, D.S.; Han, Z.X.; LAOLO, S.; SOUKSAN, P.; Liu, H.L.; Zhou, J.; et al. National-Scale Geochemical Baseline of 69 Elements in Laos Stream Sediments. Minerals 2022, 12, 1360. [Google Scholar] [CrossRef]
  30. Zhang, Y.S.; Hu, Z.G.; Liu, J.; Wang, X.Y.; Zhang, B.T.; Li, C.X.; Hua, B.; Zhang, Z.W.; Cao, Q.T.; Zhao, L.; et al. Application of stream sediment survey for prospecting the ion adsorption type REE deposit in the Lincang area, Yunnan Province. Acta Mineral. Sin. 2021, 41, 171–180, (In Chinese with English Abstract). [Google Scholar]
  31. Yang, S.P.; Kong, M.; Liu, Y.H.; Liu, H.Z.; Zhang, X.J.; Dong, G.F.; Luo, Y.P. Hydrogeochemical characteristics of the qulong copper ore district in tibet and their indication significance to copper mineralization. Geophys. Geochem. Explor. 2006, 06, 509–512, (In Chinese with English Abstract). [Google Scholar]
  32. Yang, S.P. A review and some considerations of water geochemical survey. Geophys. Geochem. Explor. 2008, 01, 13–18, (In Chinese with English Abstract). [Google Scholar]
  33. Boyle, R.W. The prospect for geochemical exploration--predictable advances and new approaches. J. Geochem. Explor. 1984, 21, 1–18. [Google Scholar] [CrossRef]
  34. Zhou, M.F.; Li, X.X.; Wang, Z.Z.; Li, X.C.; Liu, J.C. The genesis of regolith-hosted rare earth element and scandium deposits: Current understanding and outlook to future prospecting. Chin. Sci. Bull. 2020, 65, 3809–3824, (In Chinese with English Abstract). [Google Scholar] [CrossRef]
  35. Yu, Y.; Li, D.X.; Wang, D.H.; Huang, F.; Liu, X.L.; Tian, Z.X.; Deng, M.C. Distribution and impact factor of dissolved rare earth elements insurface waters in the suburb of typical ion-adsorption rare earth orefield. Earth Sci. Front. 2017, 24, 172–181, (In Chinese with English Abstract). [Google Scholar]
  36. Wang, Y.Y.; Fu, H.Y.; Lin, X.J.; Liang, X.L.; Yamaguchi, A.; Zhu, J.X.; Takahashi, Y.; Zhu, R.L. Distribution of rare earth elements (REEs) in supergene environment around a typical ion adsorption--type REE deposit. Ore Geol. Rev. 2023, 660, 679–704. [Google Scholar] [CrossRef]
  37. Cheng, K.L.; Hao, Z.D.; Zhang, P.X. The soyrces of ore-forming materials and controlling factors of main weathering deposits in guangxi. Guangxi Geol. 1996, Z1. 129–130+101–128. (In Chinese with English Abstract). [Google Scholar]
  38. Fu, W.; Zhao, Q.; Luo, P.; Li, P.Q.; Lu, Q.P.; Zhou, H.; Yi, Z.B.; Xu, C. Mineralization diversity of ion-adsorption type REE deposit in southern China and the critical influence of parent rocks. Acta Geol. Sin. 2022, 96, 3901–3925, (In Chinese with English Abstract). [Google Scholar]
  39. Fu, W.; Dong, C.F.; Xu, C.; Wang, R.H.; Lu, Q.P.; Zhou, H.; Han, Z.X.; Yi, Z.B.; Lv, Y.Z.; Huang, G.Q.; et al. Research on Prospecting Direction of Ion-Adsorption Type Heavy Rare Earth Element Resources in Guangxi and Progresses in Scientific Demonstration Exploration. J. Earth Sci. 2024, 49, 1931–1945, (In Chinese with English Abstract). [Google Scholar]
  40. Peng, S.B.; Fu, J.M.; Liu, Y.H. The Discovery and Significance of A-type Charnokite in Southeast Guangxi Province, China. Sci. Technol. Eng. 2004, 10, 832–834, (In Chinese with English Abstract). [Google Scholar]
  41. Liao, Q.K. Forming time of darongshan-shiwandashan granite batholith in guangxi. Guangxi Geol. 1991, 04, 59–68, (In Chinese with English Abstract). [Google Scholar]
  42. Wang, W.; Li, J.H.; Xin, Y.J.; Sun, H.S.; Yu, Y.Q. Zircon LA-ICP-MS U-Pb Dating and Geochemical Analysis of the Darongshan–Shiwandashan Granitoids in Southwestern South China and Their Geological Implications. Acta Geoscientica Sinica 2018, 39, 179–194, (In Chinese with English Abstract). [Google Scholar]
  43. Fang, Q.H.; Feng, J.C.; He, L.Y. The S-type granite suite in darongshan, guangxi province. Acta Petrol. Sin. 1987, 03. 23–34+100. (In Chinese with English Abstract). [Google Scholar]
  44. Zhao, L.; Guo, F.; Fan, W.M.; Li, C.W.; Qing, X.F.; Li, H.X. Crustal Evolution of the Shiwandashan in Guangxi: Insights from Zircon U-Pb Geochronology and Hf Isotopic Records of Granulite Enclaves in Indosinian Granites. Chin. Sci. Bull. 2010, 55, 1489–1500, (In Chinese with English Abstract). [Google Scholar] [CrossRef]
  45. Zhao, L.; Guo, F.; Fan, W.M.; Li, C.W.; Qin, X.F.; Li, H.X. Origin of the granulite enclaves in Indo-Sinian peraluminous granites, South China and its implication for crustal anatexis. Lithos 2012, 150, 209–226. [Google Scholar] [CrossRef]
  46. Jiao, S.J.; Li, X.H.; Huang, H.Q.; Deng, X.G. Metasedimentary melting in the formation of charnockite: Petrological and zircon U-Pb-Hf-O isotope evidence from the Darongshan S-type granitic complex in southern China. Lithos 2015, 239, 217–233. [Google Scholar] [CrossRef]
  47. Li, M.Y.H.; Zhou, M.F.; Williams-jones, A.E. Controls on the dynamics of rare earth elements during subtropical hillslope processes and formation of regolith-hosted deposits. Econ. Geol. 2020, 115, 1097–1118. [Google Scholar] [CrossRef]
  48. Chaudhuri, S.; Cullers, R.L. The distribution of rare-earth elements in deeply buried Gulf Coast sediments. Chem. Geol. 1979, 24, 327–338. [Google Scholar] [CrossRef]
  49. Zhuo, X.Z.; Ming, Q.H.; Zhang, J.J.; Zhang, L.Y.; Cheng, X.S.; Ma, L.C. Conceptual Models for Correlation between Detrital Particles Contents and Pore Distribution of Shale: Taking the Silurian Longmaxi Formation in northwestern Guizhou as an example. Acta Sedimentol. Sin. 2018, 36, 969–980, (In Chinese with English Abstract). [Google Scholar]
  50. Sun, C.X.; Nie, H.K.; Liu, G.X.; Zhang, G.R.; Du, W.; Wang, R.Y. Quartz Type and Its Control on Shale Gas Enrichment and Production:A Case Study of the Wufeng-Longmaxi Formations in the Sichuan Basin and Its Surrounding Areas, China. J. Earth Sci. 2019, 44, 3692–3704, (In Chinese with English Abstract). [Google Scholar]
  51. Yang, S.Y.; Li, C.; Wang, Z.B.; Wang, X.D.; Shu, J.S. Heterogeneity of geochemical compositions of the changjiang river sediments and provenance indication. Quat. Sci. 2013, 33, 645–655, (In Chinese with English Abstract). [Google Scholar]
  52. Ding, L.Y.; Azimi, G. Impact of particle size and associated minerals on rare earth desorption and incorporation mechanisms in a South American ion-adsorption clay. Sci. Rep. 2024, 14, 16216. [Google Scholar] [CrossRef] [PubMed]
  53. Kanazawa, Y.; Kamitani, M. Rare earth minerals and resources in the world. J. Alloys Compd. 2006, 408, 1339–1343. [Google Scholar] [CrossRef]
  54. Yang, S.Y.; Jung, H.S.; Sikchoi, M.; Li, C.X. The rare earth element compositions of the Changjiang (Yangtze) and Huanghe (Yellow) river sediments. Earth Planet. Sci. Lett. 2002, 201, 407–419. [Google Scholar] [CrossRef]
  55. Bea, F. Residence of REE, Y, Th and U in granites and crustal protoliths; implications for the chemistry of crustal melts. J. Petrol. 1996, 37, 521–552. [Google Scholar] [CrossRef]
  56. Hoshino, M.; Sanematsu, K.; Watanabe, Y. REE mineralogy and resources. Handb. Phys. Chem. Rare Earths 2016, 49, 129–291. [Google Scholar]
  57. Huang, Y.F.; He, H.P.; Liang, X.L.; Bao, Z.W.; Tan, W.; Ma, L.Y.; Zhu, J.X.; Huang, J.; Wang, H. Characteristics and genesis of ion adsorption type REE deposits in the weathering crusts of metamorphic rocks in Ningdu, Ganzhou, China. Ore Geol. Rev. 2021, 135, 104173. [Google Scholar] [CrossRef]
  58. Munksgaard, N.C.; Lim, K.; Parry, D.L. Rare earth elements as provenance indicators in North Australian estuarine and coastal marine sediments. Estuar. Coast. Shelf Sci. 2003, 57, 399–409. [Google Scholar] [CrossRef]
  59. Jung, H.S.; Lim, D.; Jeong, D.; Xu, Z.; Li, T. Discrimination of sediment provenance in the Yellow Sea: Secondary grain-size effect and REE proxy. J. Asian Earth Sci. 2016, 123, 78–84. [Google Scholar] [CrossRef]
  60. Zhang, L.Y.; Tao, C.H.; Su, X.; Lv, S.H.; Zhou, J.P.; Deng, X.M.; Yu, C.H.; Song, B. Characteristics of rare earth elements in the surface sediments of Southwest Indian Ridge: Implication of grain size for the identification of hydrothermal activity. Geo-Mar. Lett. 2022, 42, 7. [Google Scholar] [CrossRef]
  61. Ding, Z.L.; Sun, J.M.; Yang, S.L.; Liu, T.S. Geochemistry of the Pliocene red clay formation in the Chinese Loess Plateau and implications for its origin, source provenance and paleoclimate change. Geochim. Cosmochim. Acta 2001, 65, 901–913. [Google Scholar] [CrossRef]
  62. Ferrat, M.; Weiss, D.J.; Strekopytov, S.; Dong, S.F.; Chen, H.Y.; Najorka, J.; Sun, Y.B.; Gupta, S.; Tada, R.; Sinhagupta, R.; et al. Improved provenance tracing of Asian dust sources using rare earth elements and selected trace elements for palaeomonsoon studies on the eastern Tibetan Plateau. Geochim. Cosmochim. Acta 2011, 75, 6374–6399. [Google Scholar] [CrossRef]
  63. Ichimura, K.; Sanematsu, K.; Kon, Y.; Takagi, T.; Murakami, T. REE redistributions during granite weathering: Implications for Ce anomaly as a proxy for paleoredox states. Am. Mineral. J. Earth Planet. Mater. 2020, 105, 848–859. [Google Scholar] [CrossRef]
  64. Cicconi, M.R.; Losq, C.L.; Henderson, G.S.; Neuville, D.R. The redox behavior of rare earth elements. Magma Redox Geochem. 2021, 381–398. [Google Scholar]
  65. Nesbitt, H.W. Mobility and fractionation of rare earth elements during weathering of a granodiorite. Nature 1979, 279, 206–210. [Google Scholar] [CrossRef]
  66. Durn, G.; Perković, I.; Stummeyer, J.; Ottner, F.; Mileusnić, M. Differences in the behaviour of trace and rare-earth elements in oxidizing and reducing soil environments: Case study of Terra Rossa soils and Cretaceous palaeosols from the Istrian peninsula, Croatia. Chemosphere 2021, 283, 131286. [Google Scholar] [CrossRef]
  67. Dong, C.F.; Han, Z.X.; Lu, H.T.; Zhao, R.W.; Cai, Y.Q.; Li, Y.; Xu, C.; Zhang, B.M. Concentration, speciation, and fractionation of rare earth elements in alluvial soils in contiguous karst landform, southwestern China. J. Geochem. Explor. 2024, 256, 107360. [Google Scholar] [CrossRef]
  68. Li, C.S.; Shi, X.F.; Kao, S.J.; Liu, Y.G.; Lyu, H.H.; Zou, J.J.; Liu, S.F.; Qiao, S.Q. Rare earth elements in fine-grained sediments of major rivers from the high-standing island of Taiwan. J. Asian Earth Sci. 2013, 69, 39–47. [Google Scholar] [CrossRef]
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Figure 2. (a) Sampling locations of stream sediments and stream waters in Jiaping IARED and background areas in Lingshan County, Guangxi. (b) Field figures of stream sediments and stream waters. These samples include 15 samples from the Jiaping IARED within the Jiuzhou granitic pluton, 2 samples from the Devonian carbonate background area, and 2 samples from the granitic background area within the Pubei granitic pluton.
Figure 2. (a) Sampling locations of stream sediments and stream waters in Jiaping IARED and background areas in Lingshan County, Guangxi. (b) Field figures of stream sediments and stream waters. These samples include 15 samples from the Jiaping IARED within the Jiuzhou granitic pluton, 2 samples from the Devonian carbonate background area, and 2 samples from the granitic background area within the Pubei granitic pluton.
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Figure 3. SEM pictures showing the minerals observed in -150-mesh stream sediments in Jiaping IARED, Guangxi. (a) zircon, partially coated by clay minerals; (b) small-grained zircon, embedded within clay aggregates; (c) independent monazite grain; (d) xenotime, embedded in clay matrices; (e) independent xenotime grain; (f) independent cerianite grain. (Xtm: Xenotime; Kl: Kaolinite; Mnz: Monazite; Zrn: Zircon; Ctn: Cerianite; Ilm: ilmenite).
Figure 3. SEM pictures showing the minerals observed in -150-mesh stream sediments in Jiaping IARED, Guangxi. (a) zircon, partially coated by clay minerals; (b) small-grained zircon, embedded within clay aggregates; (c) independent monazite grain; (d) xenotime, embedded in clay matrices; (e) independent xenotime grain; (f) independent cerianite grain. (Xtm: Xenotime; Kl: Kaolinite; Mnz: Monazite; Zrn: Zircon; Ctn: Cerianite; Ilm: ilmenite).
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Figure 4. Chondrite-normalized REE distribution in stream waters collected in dry season and rainy season in Jiaping IARED, Lingshan county, Guangxi.
Figure 4. Chondrite-normalized REE distribution in stream waters collected in dry season and rainy season in Jiaping IARED, Lingshan county, Guangxi.
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Figure 5. Chondrite-normalized REE distributions in stream waters of Jiaping IARED and two background areas, Lingshan county, Guangxi.
Figure 5. Chondrite-normalized REE distributions in stream waters of Jiaping IARED and two background areas, Lingshan county, Guangxi.
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Figure 6. Scatter plot of (La/Sm)N versus (La/Yb)N in stream waters, bedrocks, and soils of the unmineralized layer, LREE ore layer and HREE ore layer in Jiaping IARED, Guangxi.
Figure 6. Scatter plot of (La/Sm)N versus (La/Yb)N in stream waters, bedrocks, and soils of the unmineralized layer, LREE ore layer and HREE ore layer in Jiaping IARED, Guangxi.
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Figure 7. Chondrite-normalized REE distributions in stream sediments of different grain sizes ((A) +20 mesh; (B) 20–60 mesh; (C) 60–150 mesh; (D) -150 mesh) in the Jiaping IARED and the background areas of Lingshan county, Guangxi.
Figure 7. Chondrite-normalized REE distributions in stream sediments of different grain sizes ((A) +20 mesh; (B) 20–60 mesh; (C) 60–150 mesh; (D) -150 mesh) in the Jiaping IARED and the background areas of Lingshan county, Guangxi.
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Figure 8. Scatter plots of LREE, HREE and Zr, P, Si/Al in stream sediments of different grain sizes in Jiaping IARED, Lingshan county, Guangxi. (A) a positive correlation between P and LREE; (B) a positive correlation between P and HREE; (C) a positive correlation between Zr and LREE; (D) a positive correlation between Zr and HREE; (E) a negative correlation between Si/Al and LREE; (F) a negative correlation between Si/Al and HREE. Red squares represent +20 mesh; green triangles denote 20–60 mesh; yellow circles indicate 60–150 mesh; black triangles signify -150 mesh.
Figure 8. Scatter plots of LREE, HREE and Zr, P, Si/Al in stream sediments of different grain sizes in Jiaping IARED, Lingshan county, Guangxi. (A) a positive correlation between P and LREE; (B) a positive correlation between P and HREE; (C) a positive correlation between Zr and LREE; (D) a positive correlation between Zr and HREE; (E) a negative correlation between Si/Al and LREE; (F) a negative correlation between Si/Al and HREE. Red squares represent +20 mesh; green triangles denote 20–60 mesh; yellow circles indicate 60–150 mesh; black triangles signify -150 mesh.
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Figure 9. Scatter plots of δCe versus δEu of stream sediments with different grain sizes in the Jiaping IARED and the background area of Guangxi, triangular (Jiaping IARED), circular (carbonate background area), square (granite background area).
Figure 9. Scatter plots of δCe versus δEu of stream sediments with different grain sizes in the Jiaping IARED and the background area of Guangxi, triangular (Jiaping IARED), circular (carbonate background area), square (granite background area).
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Figure 10. Scatter plot of (La/Sm)N versus (La/Yb)N in -150-mesh stream sediments, bedrocks, and soils of the unmineralized layer, LREE ore layer, and HREE ore layer in Jiaping IARED, Guangxi.
Figure 10. Scatter plot of (La/Sm)N versus (La/Yb)N in -150-mesh stream sediments, bedrocks, and soils of the unmineralized layer, LREE ore layer, and HREE ore layer in Jiaping IARED, Guangxi.
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Table 1. Geochemical characteristics of REE in different grain-sized stream sediments in Jiaping IARED and background areas. Calculation formula (N denotes chondrite-normalized values): δCe = 2CeN/(LaN + PmN), δEu = 2EuN/(SmN + GdN).
Table 1. Geochemical characteristics of REE in different grain-sized stream sediments in Jiaping IARED and background areas. Calculation formula (N denotes chondrite-normalized values): δCe = 2CeN/(LaN + PmN), δEu = 2EuN/(SmN + GdN).
Sample TypeStatistical Value (μg/g)LREEHREEL/HREEδEuδCe
+20-mesh stream sedimentsJiaping IARED (15)Median64.28 31.83 2.36 97.45 0.29 1.04
Average value108.30 43.18 2.51 151.48 0.29 1.08
Maximum value281.15 121.59 5.29 402.74 0.41 1.29
Minimum value43.80 16.81 1.48 60.61 0.17 0.98
Granite background area (2)Average value291.37 66.49 4.27 357.85 0.26 1.14
Carbonate rock background area (2)Average value187.04 58.62 3.05 245.66 0.59 0.99
20–60-mesh stream sedimentsJiaping IARED (15)Median76.40 36.56 2.56 114.97 0.31 1.07
Average value107.77 40.72 2.65 148.49 0.31 1.09
Maximum value217.96 81.81 4.36 297.92 0.39 1.34
Minimum value44.12 19.41 1.58 72.10 0.22 0.98
Granite background area (2)Average value242.52 66.11 3.78 308.63 0.28 1.19
Carbonate rock background area (2)Average value125.48 35.45 3.51 160.93 0.55 1.03
60–150-mesh stream sedimentsJiaping IARED (15)Median157.55 61.61 2.50 217.26 0.30 1.01
Average value178.60 60.16 3.00 238.75 0.30 1.06
Maximum value330.17 98.68 5.31 392.36 0.45 1.38
Minimum value84.73 34.82 1.53 128.59 0.12 0.93
Granite background area (2)Average value313.19 134.11 2.33 447.30 0.25 1.14
Carbonate rock background area (2)Average value189.68 59.34 3.22 249.01 0.57 0.99
-150-mesh stream sedimentsJiaping IARED (15)Median696.73 256.72 2.67 926.87 0.16 1.04
Average value829.53 297.51 3.02 1127.03 0.16 1.06
Maximum value1627.56 814.94 4.98 2442.50 0.31 1.26
Minimum value220.97 117.44 1.80 338.41 0.06 0.93
Granite background area (2)Average value841.77 154.51 5.45 996.28 0.19 1.08
Carbonate rock background area (2)Average value235.46 73.56 3.24 309.02 0.49 0.98
Table 2. Geochemical characteristics of dissolved REE in stream water of Jiaping IARED and background area in Guangxi.
Table 2. Geochemical characteristics of dissolved REE in stream water of Jiaping IARED and background area in Guangxi.
Sample TypeStatistical Value (ng/mL)LREEHREEL/HREEδEuδCe
Stream waterJiaping IARED (15)Median0.88 0.54 1.78 1.38 1.25 0.90
Average value1.05 0.59 1.78 1.64 1.72 0.88
Maximum value2.81 1.21 2.37 4.03 6.33 1.24
Minimum value0.16 0.09 0.90 0.25 0.80 0.28
Granite background area (2)Average value0.87 0.25 3.64 1.13 1.51 1.47
Carbonate rock background area (2)Average value0.53 0.23 2.54 0.76 1.87 0.83
Table 3. Geochemical characteristics of REE in LREE and HREE ore layers, unmineralized layers, and bedrock samples from the Jiaping IARED area.
Table 3. Geochemical characteristics of REE in LREE and HREE ore layers, unmineralized layers, and bedrock samples from the Jiaping IARED area.
Sample TypeStatistical Value (μg/g)LREEHREEL/HREEδEuδCe
LREE ore layer (26)Median737.80272.272.671010.40.640.19
Average value814.08332.073.061146.20.650.23
Maximum value1331.6814.637.612146.20.960.85
Minimum value449.9697.911.08704.190.460.10
HREE ore layer (13)Median460.02742.470.691311.50.710.36
Average value544.60820.440.681365.00.700.36
Maximum value1031.51324.20.932325.80.850.60
Minimum value306.15474.930.42800.50.560.18
Unmineralized layer (15)Median269.81 34.61 6.58 310.53 0.35 1.47
Average value272.17 50.16 6.58 322.34 0.39 1.69
Maximum value467.74 117.46 10.17 557.42 0.60 3.32
Minimum value144.43 23.45 2.59 171.94 0.23 0.85
Bedrock (5)Median215.9459.322.98275.250.580.95
Average value189.1968.252.94257.440.590.88
Maximum value230.95101.863.89293.960.720.99
Minimum value124.1646.961.52171.120.520.55
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Liu, J.; Han, Z.; Dong, C.; Wei, X.; Chen, Y. Geochemical Survey of Stream Sediments and Stream Water for Ion-Adsorption Type Rare Earth Deposits (IAREDs): A Pilot Study in Jiaping IARED, Guangxi, South China. Minerals 2025, 15, 642. https://doi.org/10.3390/min15060642

AMA Style

Liu J, Han Z, Dong C, Wei X, Chen Y. Geochemical Survey of Stream Sediments and Stream Water for Ion-Adsorption Type Rare Earth Deposits (IAREDs): A Pilot Study in Jiaping IARED, Guangxi, South China. Minerals. 2025; 15(6):642. https://doi.org/10.3390/min15060642

Chicago/Turabian Style

Liu, Junhong, Zhixuan Han, Chunfang Dong, Xiaocheng Wei, and Yingnan Chen. 2025. "Geochemical Survey of Stream Sediments and Stream Water for Ion-Adsorption Type Rare Earth Deposits (IAREDs): A Pilot Study in Jiaping IARED, Guangxi, South China" Minerals 15, no. 6: 642. https://doi.org/10.3390/min15060642

APA Style

Liu, J., Han, Z., Dong, C., Wei, X., & Chen, Y. (2025). Geochemical Survey of Stream Sediments and Stream Water for Ion-Adsorption Type Rare Earth Deposits (IAREDs): A Pilot Study in Jiaping IARED, Guangxi, South China. Minerals, 15(6), 642. https://doi.org/10.3390/min15060642

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