# Cadmium-Fe-Mn coupling in sphalerite from MVT Pb-Zn deposits: Implications for critical metal Cd enrichment

Pan-Pan Niu, Shao-Yong Jiang, Manuel Muñoz, Nicolas Trcera, Shugang Xiao

► To cite this version:

Pan-Pan Niu, Shao-Yong Jiang, Manuel Muñoz, Nicolas Trcera, Shugang Xiao. Cadmium-Fe-Mn coupling in sphalerite from MVT Pb-Zn deposits: Implications for critical metal Cd enrichment. Ore Geology Reviews, 2025, 186 (9), pp.106880. 10.1016/j.oregeorev.2025.106880. hal-05311386

HAL Id: hal-05311386

https://hal.science/hal-05311386v1

Submitted on 16 Oct 2025

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
# Cadmium-Fe-Mn coupling in sphalerite from MVT Pb-Zn deposits: Implications for critical metal Cd enrichment

Pan-Pan Niu<sup>a,b</sup>, Shao-Yong Jiang<sup>b,c,*</sup> <sup>†</sup>, Manuel Muñoz<sup>d</sup>, Nicolas Trcera<sup>e</sup>, Shugang Xiao<sup>c</sup>

## ARTICLE INFO

### Keywords:

Cadmium (Cd)

Manganese (Mn)

Iron (Fe)

Sphalerite

MVT deposits

## ABSTRACT

Cadmium (Cd) has been increasingly recognized for its critical role in modern high-technology applications. Accordingly, investigations into its natural enrichment mechanisms have garnered heightened scientific interest. The Pb-Zn deposit, recognized as the principal industrial source of Cd, predominantly hosts this element within sphalerite, with only minor occurrences in independent Cd minerals such as greenockite (CdS). Current studies have demonstrated that the distribution of Cd in sphalerite is significantly correlated with Fe and Mn, particularly through the substitutions of Cd, Fe, and Mn, such as $Fe^{2+} + Mn^{2+} + Cd^{2+} \rightarrow 3Zn^{2+}$ and $Fe^{2+} + Cd^{2+} \rightarrow 2Zn^{2+}$. However, the coupling mechanism of these elements within sphalerite have not been thoroughly investigated, and the implications of the Cd enrichment process remains poorly understood. In this study, we analyzed sphalerite samples of varying colors from two major Mississippi Valley-type (MVT) Pb-Zn deposits (Huize and Maoping) in the SYG (Sichuan-Yunnan-Guizhou) area, Southwest China. We employed micro-X-ray fluorescence (μ-XRF), laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS), synchrotron X-ray fluorescence (SXRF), and X-ray absorption near-edge structure (XANES) spectroscopy techniques to qualitatively and quantitatively investigate the presence of Cd, Fe and Mn in sphalerite of different colors. The results demonstrate that Fe in our sphalerite samples exists in a divalent state ($Fe^{2+}$), with concentrations ranging from 1.2 to 10.8 wt%. In Fe-rich sphalerite, Cd and Mn incorporate into the lattice alongside Fe at varying ratios via the substitutions $Cd^{2+} + nFe^{2+} \rightarrow (n + 1)Zn^{2+}$ and $Mn^{2+} + nFe^{2+} \rightarrow (n + 1)Zn^{2+}$, respectively. Notably, as Fe content increases further, both the Cd/Fe and Mn/Fe ratios decrease progressively. Cd concentrations drop sharply when Fe exceeds 6.7 wt%. In Fe-poor sphalerite, Cd and Mn can directly substitute for Zn within the crystal structure ($Cd^{2+} \rightarrow Zn^{2+}$ and $Mn^{2+} \rightarrow Zn^{2+}$), and their concentrations exhibit an inverse correlation. This study indicates that the enrichment of Cd within sphalerite is predominantly influenced by temperature, while its correlation with sulfur fugacity appears to be insignificant. Cadmium enrichment can occur in both high-temperature and low-temperature sphalerite. Consequently, the Pb-Zn deposits formed under higher temperature conditions may facilitate two distinct stages of Cd enrichment in sphalerite, thereby enhancing overall Cd concentration.

## 1. Introduction

Sphalerite is an important host mineral that incorporates a diverse array of trace elements, such as Fe, Cd, Ge, Ga, Re, Tl, In, Sn, As, Mn, Cu, Pb, Se and Ag (Cook et al., 2009; Ye et al., 2011; Bauer et al., 2019; Xu

et al., 2021; Marsh et al., 2016). These elements can enter the sphalerite crystal lattice through solid solutions (element substitution) or occur within nano-scale mineral inclusions that coexist with sphalerite, thereby contributing to their enrichment (Höll et al. 2007; Wen et al., 2019, 2020; Liu et al., 2023; Niu et al., 2024). Lattice-bounded

<footnote><sup>a</sup> State Key Laboratory of Deep Earth Processes and Resources, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, PR China</footnote>

<footnote><sup>b</sup> State Key Laboratory of Geological Processes and Mineral Resources, Collaborative Innovation Center for Exploration of Strategic Mineral Resources, School of Earth Resources, China University of Geosciences, Wuhan 430074 Hubei Province, PR China</footnote>

<footnote><sup>c</sup> Expert Workstation, Geological Team 308, Yunnan Bureau of Nonferrous Geology, Kunming 650214 Yunnan Province, PR China</footnote>

<footnote><sup>d</sup> Geosciences Montpellier, University of Montpellier, CNRS, Montpellier 34095, France</footnote>

<footnote><sup>e</sup> Synchrotron SOLEIL, 91192 Gif-sur-Yvette, France</footnote>

<footnote>* Corresponding author at: State Key Laboratory of Geological Processes and Mineral Resources, Collaborative Innovation Center for Exploration of Strategic Mineral Resources, School of Earth Resources, China University of Geosciences, Wuhan 430074, Hubei Province, PR China.</footnote>

<footnote>E-mail address: shyjiang@cug.edu.cn (S.-Y. Jiang).</footnote>
<figure><img src="image_2.png" /><figcaption>**Fig. 1.** (A) The distribution of MVT Pb-Zn deposits in China and the location of the studied SYG area (after Yin et al., 2012). (B) Regional geological schematic diagram of the SYG triangle area and the locations of numerous Pb-Zn deposits (after Kong et al., 2018).</figcaption></figure>

incorporation is typically inferred from the correlation of elemental
composition in sphalerite. In contrast, the presence of nano-scale min-
erals is identified using techniques such as atom probe tomography
(Fougerouse et al., 2023) or transmission electron microscopy (Luo
et al., 2025; Sun et al., 2023). As a critical metal, Cd is primarily sourced
from Pb-Zn ores, where it is incorporated into sphalerite through
elemental substitution (Cook et al., 2009; Pfaff et al., 2011; Frenzel
et al., 2016; Wen et al., 2020; Jiang et al., 2023). Nevertheless, some
studies have indicated that Cd may also occur as independent minerals
at micrometer to nanometer scales, (e.g., greenockite and otavite;
Schwartz, 2000; Ye et al., 2010). Nano greenockite coexisting with
sphalerite is widely considered to result from the plastic deformation of
sphalerite, which induces Cd reactivation and subsequent

re-precipitation in the form of a solid solution (Duan et al., 2023; Yan
et al., 2025). Moreover, both greenockite and otavite are commonly
observed in the supergene oxidation zone of Pb-Zn mineralization,
indicating a strong genetic relationship between their formation and
supergene oxidation processes (Ye et al., 2012; Maghfouri et al., 2020).
However, it is noteworthy that the majority of these independent Cd
minerals occur as extremely fine-grained particles and are present in
minimal quantities, indicating that Cd in the sphalerite lattice consti-
tutes the primary source of Cd in Pb-Zn deposits. Therefore, investi-
gating the enrichment mechanism of Cd within sphalerite is of particular
significance.

Extensive research has been carried out on the substitution mecha-
nisms of Cd in sphalerite. Pfaff et al. (2011) reported a distinct negative
<figure><img src="image_3.png" /><figcaption>**Fig. 2.** Geological schematic map of the Huize Pb-Zn deposit, showing the locations of major Qilinchang and Kuangshanchang, along with small Xiaoheji, Baikuangshan, Dashuijing and Xiaocaiyuan (after Han et al., 2019).</figcaption></figure>

linear correlation between Cd + Fe + Mn and Zn in sphalerite from the Wiesloch Pb-Zn deposit in southwestern Germany. This correlation indicates the substitution of (Fe²⁺, Mn²⁺, Cd²⁺) → 3Zn²⁺. Bonnet et al. (2014) identified the substitution of Fe²⁺+Cd²⁺ → 2Zn²⁺ in a MVT Pb-Zn deposit in Tennessee, USA. Wu et al. (2019) analyzed the trace elements in sphalerite from the Daliangzi deposit, China, and confirmed the substitution (Fe²⁺, Cd²⁺) → 2Zn²⁺. However, multiple studies have shown that Cd are significantly enriched in Fe-poor sphalerite (e.g., Cook et al., 2009; Belissont et al., 2014; Zhu et al., 2017). The enrichment of Cd in sphalerite is primarily governed by a combination of factors, including the Cd/Zn ratio, pH, and the redox state of the ore-forming fluid (Schwartz, 2000; Paradis et al., 2023; Chen et al., 2024; Shu et al., 2024; Wang et al., 2024). Nevertheless, the specific role of temperature in regulating Cd enrichment remains a subject of ongoing scientific debate. Some researchers argue that elevated temperatures promote the enrichment of Cd in sphalerite (e.g., Schwartz, 2000; Wen et al., 2016; Wang et al., 2024), whereas others suggest that low-temperature hydrothermal fluids are more favorable for Cd incorporation into sphalerite (Bauer et al., 2019; Chen et al., 2024; Shu et al., 2024). Therefore, the precise influence of temperature on Cd enrichment in sphalerite remains to be fully elucidated through further investigation. Mississippi Valley-Type (MVT) Pb-Zn deposits represent one of the most significant ore deposit types hosting sphalerite (Leach and Sangster, 1993; Leach et al., 2005, 2010). China hosts several globally recognized MVT Pb-Zn metallogenic provinces, represented by the SYG (Sichuan-Yunnan-Guizhou) area and western Qinling area (Wang et al., 2014; Leach and Song, 2019). The SYG triangle in southwestern China is the largest MVT Pb-Zn metallogenic province in China, comprising over 400 deposits (and occurrences), with a total Pb-Zn resource of 2 Mt and average grades of 10 wt% Zn and 5 wt% Pb (Zhou et al., 2014, 2018). Among these, the Huize and Maoping Pb-Zn deposits were selected to investigate the elemental substitution behavior and enrichment mechanisms of Cd within sphalerite, with the aim of providing valuable insights for the exploration of Cd resources in Pb-Zn deposits.

## 2. Regional geology

The SYG triangle is located in southwest China (Fig. 1A), and is bounded by three major fault systems: the NS-trending Anninghe fault, NE-trending Mile-Shizong fault, and the NS-trending Weining-Shuicheng fault (Fig. 1B). The exposed strata are composed of (1) Paleoproterozoic basement, (2) Mesoproterozoic-Neoproterozoic basement, and (3) Overlying sedimentary cover (Fig. 1A; Yin et al., 2012; Zhu et al., 2020). The first two units are represented by the Kangding Formation and Kunyang/Huili Formation, respectively, and the overlying sedimentary cover constitutes the dominant lithology in the exposed strata of the area (Fig. 1B; Xu et al., 2020; Niu et al., 2024). The Kangding Formation comprises primarily granitic, diorite and plagioclase gneiss with minor granulite, while the Kunyang/Huili Formation consists of metamorphosed marine clastic, volcanic, and carbonate rocks (Zhou et al., 2014; Bao et al., 2017). Since the Neoproterozoic Ediacara period, both marine and continental sedimentary sequences have been deposited in a passive continental margin environment, with deposition continuing until the Middle Triassic period (Fig. 1B; Zhang et al., 2015; Zhao et al., 2023). The Ediacaran strata consist of heterogeneous sandstone, volcanic rock and dolomite, which are scattered throughout the southwest of the SYG triangle (Xu et al., 2020; Zhu et al., 2020). The Cambrian sediments are mainly composed of variegated sandstone/shale, siliceous rock and dolomite (Fig. 1B; Han et al., 2019; Xiang et al., 2020). The Ordovician-Triassic sedimentary units, which occupy a large area in the eastern SYG triangle, contain limestone and dolomite interbedded with silica-argillaceous shale and quartz sandstone. The Jurassic to Quaternary sediments comprises terrigenous sandstones, conglomerates and freshwater marls (Zhang et al., 2015; Niu et al., 2023). The Emeishan basalts, the most significant magmatic rocks in the region, were generated by a large mantle plume during the late Permian (He et al., 2010; Shellnutt, 2014).

The N-, NW- and NE-trending faults constitute the primary tectonic framework of the SYG triangle (Fig. 1B). The Anninghe and Xiaojiang faults dominate the N-trending structures, accompanied by numerous secondary faults that collectively define the tectonic framework on the western side of the area (Han et al., 2015; Xiang et al., 2020). The Mile-Shizong and Weining-Shuicheng faults, representing the NW- and NE-
<figure><img src="image_4.png" /><figcaption>**Fig. 3.** A geological schematic map of the Maoping district, also shown the spatial distribution of major I-III ore belt, Shuilu, Qiangcengdong, and Hongjianshan (after Niu et al., 2023).</figcaption></figure>

trending fault systems, respectively, play a key role in controlling the spatial distribution of Pb-Zn deposits in the eastern part of the SYG triangle (Fig. 1B; Niu et al., 2023; Wang et al., 2023). More than 400 Pb-Zn deposits (and occurrences) are distributed throughout the SYG triangle, represented by Huize, Maoping, Daliangzi, Maozu and Tianbaoshan (Fig. 1B). Notably, these deposits are characterized by elevated Pb-Zn grades (20–35 wt%) and significant enrichment of critical metals (e.g., Ge, Cd, Ga), relative to other MVT Pb-Zn deposits in the world (Leach et al., 2005; Marsh et al., 2016; Leach and Song, 2019).

### 3. Deposit geology and sphalerite texture

As the largest deposit in the SYG triangle, Huize contains more than 8 Mt of Pb-Zn metals with an average grade >25 wt%. It is primarily hosted in the Qilinchang and Kuangshanchang ore blocks, with minor Xiaocaiyuan, Dashuijing, Xiaoheiji and Baikuangshan ore blocks (Fig. 2; Meng et al., 2019; Niu et al., 2024). In addition to Pb and Zn, the deposit also contains economically recoverable by-products, including Cd (233–488 g/t), Ag (46–100 g/t), and Ge (30–81 g/t), which are increasingly important for various industrial applications (Huang et al., 2004; Han et al., 2019). Major NE-trending faults define the boundaries between stratigraphic units and are crosscut by minor NW-trending faults, which together control the spatial distribution of Pb-Zn ore blocks (Fig. 2; Han et al., 2007; Bao et al., 2017). Most ore bodies exhibit bedding-conformable, vein-like, lentoid, stockwork, and lenticular forms, and are distributed along interbedded faults and fractured zones (Han et al., 2007; Niu et al., 2024). The boundaries and contact relationships between these Pb-Zn ore bodies and the wall rock suggest an epigenetic ore-forming process.

The exposed strata in the Huize deposit are composed of the Ediacara Dengying Formation, Cambrian Qiongzhusi Formation, Devonian Haikou and Zaige Formations, Carboniferous Datang, Baizuo, Weining and Maping Formations and Permian Liangshan, and Qixia-Maokou Formations, together with the Emeishan basalts (Fig. 2; Oyebamiji et al., 2023; Niu et al., 2024). The Dengying Formation is predominantly composed of light gray to grayish-white siliceous dolomite (Wang et al., 2020; Tang et al., 2021). The Qiongzhusi Formation mainly consists of

black argillaceous shale with interbedded yellow sandstone layers. The Haikou Formation comprises light gray to light yellow siltstone interbedded with green and grayish-black argillaceous shale. The Zaige Formation includes gray cryptocrystalline limestone, yellowish-white to flesh-red medium- to coarse-grained dolomite, and yellow thin-bedded calcareous shale (Bao et al., 2017; Han et al., 2019). The Datang Formation is composed of gray brecciated limestone, cryptocrystalline limestone, and oolitic limestone. The Baizuo Formation is characterized by grayish-white coarse-grained dolomite interbedded with dolomitic limestone (Bao et al., 2017; Han et al., 2015). The Weining Formation consists of light gray limestone with intercalations of oolitic limestone and dolomitic limestone (Zhao et al., 2023; Wang et al., 2023). The Maping Formation is composed of purple-red and yellowish-green limestone. The Liangshan Formation is characterized by alternating layers of carbonaceous shale and quartz sandstone. The Qixia-Maokou Formation is predominantly composed of deep gray to light gray limestone and dolomitic limestone.

The Maoping deposit contains more than 2.5 Mt Pb-Zn metals with average grades of 6.1 wt% Pb and 14.2 wt% Zn, together with 182 t Ge at grade of 24 g/t and 580 t Ag at grade of 75 g/t (Wei et al., 2015; Niu et al., 2023). Bounded by the NW-trending Luoze river, the eastern I-III ore belt and the western Shuilu, Qiangcengdong and Hongjianshan ore belts constitute principal part of the Maoping Pb-Zn deposit (Fig. 3; Wu et al., 2021; Wang et al., 2023). The Shimenkan anticline, a short-axis plunging anticline, serves as the primary ore-controlling structure of the Maoping Pb-Zn deposit. Its axial trace exhibits an S-shaped curvature from north to south, suggesting multiple episodes of late-stage deformation (Fig. 3). The western limb of the anticline is steeply dipping, ranging from 65° to 86°, whereas the eastern limb dips more gently, between 17° and 35° (Wei et al., 2015; Zhao et al., 2023). Strata within the Shimenkan anticline become progressively younger from the core toward the flanks, with Emeishan basalts exposed exclusively on the northwest side of the Maoping deposit (Fig. 3). Similar to those in Huize, the ore bodies in the Maoping deposit generally occur in a strata-bound manner and exhibit characteristics such as pinch-and-reappear, expansion-and-contraction, and transitions from gently dipping and wide to steeply dipping and narrow (Fig. 3; Xiang et al., 2020; Niu et al., 2023;
<figure><img src="image_5.png" /><figcaption>**Fig. 4.** The mineral paragenesis during the mineralization process of the Huize and Maoping deposits, along with the formation sequence of sphalerites with distinct colors in the second hydrothermal stage.</figcaption></figure>

Zhao et al., 2023).

The Devonian Zaige Formation, the Carboniferous Datang, Baizuo, and Weining Formations, and the Permian Liangshan and Qixia-Maokou Formations are exposed in the Maoping deposit (Fig. 3). Their petrographic characteristics are comparable to those observed in the Huize area and are therefore not discussed in detail here. The main ore-bearing units are the Devonian Zaige Formation (off-white thick coarse-grained dolomite with thin carbonaceous shale) and the Carboniferous Weining and Baizuo Formations (gray-green medium-thick layers of fine-grained limestone, quartz sandstone and black shale) (Xiang et al., 2020; Wei et al., 2021).

The Huize and Maoping deposits experienced similar hydrothermal mineralization processes, which can be categorized into three distinct hydrothermal stages: (1) dolomite-pyrite veins, (2) sphalerite-galena veins, and (3) calcite veins (Fig. 4). Dolomite-pyrite veins are commonly disseminated and interspersed with sphalerite-galena veins in Stage II (Fig. 5A, B). In Stage III, calcite veins cut across and enclose the sphalerite-galena breccia and veins in Stage II (Fig. 5C, D).

In both Huize and Maoping, Stage II represents the main period of sphalerite mineralization and contains sphalerite of various colors under natural light. As a transparent mineral, sphalerite exhibits color variations depending on light intensity, which complicates classification. Therefore, we focused exclusively on its color under natural light rather than under microscopic conditions. Consequently, six different colors of sphalerite have been identified in the Huize deposit, including black (H1), brown red (H2), orange red (H3), deep yellow (H4), pale yellow (H5) and white (H6). In the Maoping deposit, five colors are recognized: black (M1), brown red (M2), deep yellow (M3), light yellow (M4) and light red (M5) colors (Fig. 6A-F; Fig. 7A-F; Niu et al., 2023, Niu et al., 2024). Based on extensive petrographic observations, we previously established that these differently colored sphalerites follow specific

<figure><img src="image_6.png" /><figcaption>**Fig. 5.** (A, B) Underground photographs of the Huize deposit, showing pyrite veins in Stage I and sphalerite-galena veins in Stage II. (C, D) Calcite veins in Stage III cutting and replacing sphalerite-galena veins in Stage II in the Maoping deposit.</figcaption></figure>
<figure><img src="image_7.png" /><figcaption>**Fig. 6.** Photos of different colored sphalerite from the Huize and Maoping deposits in Stage II. (A) Central H1 sphalerite surrounded by peripheral H2, H3, H4 and H5 sphalerite in the Huize deposit. (B) Sphalerite particles composed of H1 and H2 distributed in calcite veins in the Huize deposit. (C) H4 and H5 sphalerite veins in calcite veins in the Huize deposit. (D) M1 and M2 sphalerite associated with dolomite in the Maoping deposit. (E) Granular M3 sphalerite distributed within massive M4 sphalerite in the Maoping deposit. (F) Symbiotic M3 and M4 sphalerite interspersed with M5 sphalerite veins in the Maoping deposit. Abbreviations: H1- black, H2- brown red, H3- orange red, H4- deep yellow, H5- light yellow, H6- white in the Huize deposit; H1- black, H2- brown red, H3- deep yellow, H4- light yellow, H5- light red in the Maoping deposit; (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)</figcaption></figure>

formation sequences: (1) H1 → H2 → H3 → H6 and H1 → H2 → H4 → H5 → H6 in the Huize deposit (Fig. 4; Niu et al., 2024); (2) M1 → M2 → M3 → M4 → M5 in the Maoping deposit (Fig. 4; Niu et al., 2023), which will not be further detailed in this paper.

In Huize, the earliest-formed H1 sphalerite is commonly surrounded by later H2, H3 and H4 sphalerite (Fig. 6A-C). H1 sphalerite was the first to crystallize, and some H2, H5 and H6 sphalerite deposited both internally and along the margins (Fig. 7A). Zones of H4 and H5 sphalerite occur at the periphery of H1 and H2 sphalerite (Fig. 7B). On the inner side of galena and pyrite, massive H2 and H3 sphalerite coexist with veins of H1 and H2 sphalerite (Fig. 7C). In Maoping, M1 and M2 sphalerite are closely associated with dolomite in Stage I, while M3 and M4 sphalerite commonly coexist and are interspersed with the latest M5 sphalerite (Fig. 6D-F). The dominant M1 and M2 sphalerite is interspersed with late fine-veined M5 sphalerite and galena (Fig. 7D). At the margins of pyrite veins, minor M2 and M3 sphalerite with zoned structures are observed, followed by widespread M3 and M4 sphalerite accompanied by galena (Fig. 7E). The M1 and M2 sphalerite assemblages are interspersed and subsequently replaced by the late-stage veined M5 sphalerite (Fig. 7F). The contents of Cd, Fe, and Mn in the differently colored sphalerite from Huize and Maoping are summarized in Table 1, and detailed dataset are presented in Supplementary Table S1.

# 4. Analytical methods

## 4.1. µ-XRF mapping of sphalerite

The µ-XRF (micro-X-ray fluorescence) element mapping analysis was conducted at Tuoyan Testing Technology Co., Ltd., Guangzhou, China, using a German Bruker M4 Plus X-ray fluorescence analyzer. This instrument employs a set of multi-conductance capillary X-ray lenses as a light source and is equipped with two XFlash® silicon drift detectors with operating parameters of 50 kV, 300 µA and 2 mbar (Sarjoughian

et al., 2020; Niu et al., 2023). Prior to analysis, the sample surface was carefully cleaned with a washing ear ball or air gun to remove floating dust and impurities, and then the sample was fixed to the objective table and focused to the optimum position. The selected area was scanned with a 20 µm resolution and a dwell time of 5 ms/pixel. Two sphalerite samples from Huize (Sample 1 KS-1740-19) and Maoping (Sample 2 20MP-4-1) were selected for µ-XRF mapping analysis. The raw data were processed through M4 Tornado software to obtain element mapping for Zn, S, Fe and Pb.

## 4.2. LA-ICP-MS mapping of sphalerite

Trace element mapping analysis of sphalerite was carried out at the Analytical Laboratory of Nanjing FocuMS Technology Co. Ltd. through a laser denudation system of PMI Analyte HE 193-nm ArF Excimer connected with an Agilent 7900 ICP-MS. The two-chamber sample storehouse designed by the Laurin Technic Company has a large space and fast purge function. During the analysis, we used helium as the carrier gas and argon as the compensating gas, which were mixed together through a T-joint into the ICP system (Ning et al., 2017; Niu et al., 2023). Surface scanning was achieved by scanning multiple parallel lines, in which the working parameters were a beam spot diameter of 100-120 µm, denudation frequency of 10 Hz, and denudation energy of 2-3 J/cm², and line spacing matching the laser spot size. Each 30 s background signal was collected before and after each denudation, and the standard samples used were NIST 610 and GSE-1G. The raw data were analyzed and imaged through LIMS software (based on MATLAB), which automatically corrects instrument signal drift and background subtraction (Xiao et al., 2018).

## 4.3. Synchrotron X-ray fluorescence (SXRF) mapping and X-ray absorption fine structure (µ-XAFS)

The synchrotron analysis of sphalerite was accomplished at the Lucia
<figure><img src="image_8.png" /><figcaption>**Fig. 7.** Transmitted light images of different colored sphalerite in the Huize and Maoping deposits. (A) Massive H1 sphalerite and small amounts of H2, H5 and H6 sphalerite outside and inside in Huize; (B) Huize H1 and H2 sphalerite, along with some H4 and H5 sphalerite with zonal structures; (C) Huize H2 and H3 sphalerite as well as veined H1 and H2 sphalerite between pyrite and galena veins; (D) Dominant M1 and M2 sphalerite interspersed with little fine veined M5 sphalerite in Maoping; (E) Maoping pyrite veins covered by massive M3 and M4 sphalerite and slight M2 sphalerite and galena; (F) M1 and M2 sphalerite assemblage crosscutting by some veined M5 sphalerite; Abbreviations: (A-C) H1- black, H2- brown red, H3- orange red, H4- deep yellow, H5- light yellow, H6- white, Py- pyrite, Gn- galena; (D-F) M1- black, M2- brown red, M3- deep yellow, M4- light yellow, M5- light red, Py- pyrite, Gn- galena; (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)</figcaption></figure>

Beamline of the French National Synchrotron Radiation (SOLEIL Synchrotron) in Paris, France, through proposal number 20220771 (Vantelon et al., 2016). The SOLEIL light source operates at a nominal energy of 2.75 GeV and a current of 430 mA, and the energy range assigned to the Lucia beamline is from 0.8-8.0 keV (Debret et al., 2014; Janots et al., 2015). The double-crystal Si (111) monochromator and Kirkpatrick-Baez (KB) geometry together focuses the incident X-ray beam to 3 × 3 µm² for analysis (Qiu et al., 2021). During SXRF mapping analysis, the step size and dwell time were set as 5–20 µm and 0.2 s, respectively. The scanning energy of 7300 eV was set to obtain Fe and Mn mappings, and the Zn, Cd and S element mappings were collected at 3580 eV. For µ-XAFS analysis, the energy range of 7050–7300 eV was set to scan the Fe K-edge signals. The step sizes were set to 2.0 eV, 0.2 eV and 2.0 eV for collecting pre-edge, near-edge and post-edge energy signals, respectively.

The raw SXRF mapping data were processed via PyMCA software, and the element maps of Zn, S, Cd, Fe, and Mn were derived (Solé et al., 2007). The µ-XAFS data were background subtracted, normalized and corrected for self-absorption through Athena software (part of the DEMETER package; Ravel and Newville, 2005).

# 5. Results

## 5.1. Major element distribution in sphalerite

In Sample 1 (KS-1740-19), sphalerite of various colors (H1, H2, H4 and H6) exhibits rhythmic bands and coexists with minor pyrite grains (Fig. 8A). Among these sphalerite varieties, the Zn signal strongly interferes with the Fe signal (Fig. 8B, C), while the S signal intensity is relatively low in Fe-rich regions (Fig. 8B-D). In pyrite, the signals of S, Fe, and Pb are more pronounced compared to those in sphalerite (Fig. 8C-E). For Sample 2 (20-MP-4-1), the primary M2 sphalerite is surrounded and partially enclosed by M1 and M4 sphalerite (Fig. 8F). Excluding pyrite, M1 sphalerite has the weakest Zn signal but the strongest Fe signal. From M1 to M2 sphalerite, Zn signals gradually increase and Fe signals decrease (Fig. 8G, I). All sphalerite colors show uniform S signals and weak Pb signals (Fig. 8H, J).

The Zn and Fe contents in the sphalerite from the Huize and Maoping deposits exhibit a strong positive correlation. In Huize deposit, the Fe content in sphalerite gradually decreases from H1 (1.33–10.78 %) and H2 (4.10–6.34 %) to H4 (1.37–2.35 %), H5 (1.23–2.13 %), and H6 (0.01–0.27 %; Table S1). The Fe (0–1.41 %) contents in H3 sphalerite are comparable to those of H6 sphalerite (Niu et al., 2024). In Maoping deposit, the Fe content in M1 sphalerite ranges from 4.25 % to 7.98 %. The M2 sphalerite contains Fe within the range of 2.11 % to 3.29 %,
<caption>**Table 1**</caption>

Summary of Fe (wt. %), Cd (ppm) and Mn (ppm) contents in sphalerite of different colors from the Huize and Maoping deposits.

<table><thead><tr><th></th><th>Fe (average) content</th><th>Cd (average) content</th><th>Mn (average) content</th><th>References</th></tr></thead><tbody><tr><td colspan="5"><strong>Huize sphalerite</strong></td></tr><tr><td>C1</td><td>1.33–10.78<br>(6.87)</td><td>958–3275<br>(1912)</td><td>41–173 (109)</td><td rowspan="3">Niu et al., 2024</td></tr><tr><td>C2</td><td>4.10–6.34<br>(5.27)</td><td>1531–3610<br>(2288)</td><td>65–148 (93)</td></tr><tr><td>C3</td><td>0–1.41 (0.14)</td><td>846–1603<br>(1180)</td><td>73–186 (122)</td></tr><tr><td>C4</td><td>1.37–2.35<br>(1.83)</td><td>776–1775<br>(1030)</td><td>15–113 (52)</td><td></td></tr><tr><td>C5</td><td>1.23–2.13<br>(1.65)</td><td>922–1246<br>(1106)</td><td>23–50 (31)</td><td></td></tr><tr><td>C6</td><td>0.01–0.27<br>(0.08)</td><td>1310–2288<br>(1654)</td><td>1–71 (16)</td><td></td></tr><tr><td colspan="5"><strong>Maoping sphalerite</strong></td></tr><tr><td>C1</td><td>4.25–7.98<br>(6.27)</td><td>508–1372<br>(805)</td><td>2–79 (53)</td><td rowspan="3">Niu et al., 2023</td></tr><tr><td>C2</td><td>2.11–3.29<br>(2.58)</td><td>388–724 (540)</td><td>17–36 (28)</td></tr><tr><td>C3</td><td>1.13–2.54<br>(1.86)</td><td>516–1115<br>(645)</td><td>11–46 (25)</td></tr><tr><td>C4</td><td>0.85–2.23<br>(1.23)</td><td>611–1411<br>(814)</td><td>12–93 (24)</td><td></td></tr><tr><td>C5</td><td>0–0.08 (0.02)</td><td>648–2304<br>(1284)</td><td>5–26 (9)</td><td></td></tr></tbody></table>

whereas the Fe content in M3 sphalerite varies from 1.13 % to 2.54 % (Table S1). The Fe content in M4 sphalerite ranges between 0.85 % and 2.23 %. In contrast, M5 sphalerite exhibits significantly lower Fe concentrations, ranging from 54 to 401 ppm (Niu et al., 2023).

## 5.2. Trace element distribution in sphalerite

In Sample 1 (QL-1331-2), the analyzed area includes H1, H2 and H3 sphalerite, along with pyrite veins (Fig. 9A, B). The Zn and S signals remain constant across all sphalerite domains (Fig. 9C, D). Iron, Mn and Sn are predominantly enriched in H1 sphalerite, followed by H2 and H4 sphalerite (Fig. 9E, G, M). Silver, Cd and Ge show slightly higher concentrations in H1 and H2 sphalerite compared to H4 sphalerite (Fig. 9H, I, K). The signal intensities of Ga, In and Sb in sphalerite do not correlate directly with sphalerite colors (Fig. 9J, L, N).

Sample 2 (20MP-2-2) is a colorful sphalerite composed of M1, M2 and M3 domains with minimal internal pyrite (Fig. 10A, B). Pyrite interferences are evident in the Zn, S, Fe, Cd and Sb signals, relative to sphalerite (Fig. 10C-E, H, N). Excluding pyrite, Zn and S signals show no significant variation within the selected region (Fig. 10C, D). The Fe, Ga, Cd and Mn signals correlate with the color bands in sphalerite. Specifically, Fe, Ga and Mn are predominantly enriched in M1 sphalerite, whereas Cd is primarily enriched in M2 sphalerite (Fig. 10E, G, I, J). Copper, Ag, Ge and Sb demonstrate minor band-related variations in signal strength (Fig. 10F, H, K, N), whereas the In and Sn signals are insignificant (Fig. 10L, M).

The trace element data for the Huize and Maoping sphalerite have been documented in Niu et al. (2023, 2024). In this study, we focus specifically on presenting the concentrations of Cd and Mn. In Huize, Cd concentrations in H1 and H2 sphalerite range from 958 to 3275 ppm and 1531 to 3610 ppm, respectively. H6 sphalerite also contains a notable Cd component, ranging from 1310 to 2288 ppm, although slightly lower than in H1 and H2. In contrast, Cd contents in H3, H4, and H5 sphalerite are significantly lower (Table S1). Manganese is enriched in H1, H2, and H3 sphalerite, with concentrations ranging from 41 to 173 ppm, 65 to 148 ppm, and 73 to 186 ppm, respectively. These values are slightly

higher than those observed in H4 (15–113 ppm), H5 (23–50 ppm), and H6 sphalerite (1–71 ppm; Table S1). In Maoping, the highest Cd concentrations are observed in M5 sphalerite, with values ranging from 648 to 2305 ppm, followed by M1 sphalerite, which contains 508–1372 ppm Cd (Niu et al., 2023). The Cd concentrations display a gradual increase from M2 sphalerite (388–724 ppm), through M3 sphalerite (516–1115 ppm), to M4 sphalerite (611–1412 ppm; Table S1). The Mn contents in M1 sphalerite, ranging from 2 to 79 ppm, are the highest among all studied sphalerite types and significantly exceed those in M2 sphalerite (17–40 ppm). The M3, M4, and M5 sphalerite exhibit Mn concentrations of 11–46 ppm, 12–93 ppm, and 5–26 ppm, respectively (Table S1).

## 5.3. SXRF mapping and μ-XAFS analysis of Fe in sphalerite

Sphalerite samples with relatively high Fe contents were selected for μ-XAFS analysis. Prior to this, SXRF mapping analysis was performed to determine the spatial distributions of Zn, S, Cd, Fe, and Mn signals. In the Huize samples, a sphalerite domain exhibiting a rhythmic structure, including H1, H2, H4 and H5, was selected for Fe K-edge spectra analysis (Fig. 7B). Two LA-ICP-MS spot analyses revealed that H1 sphalerite contains Fe contents ranging from 69,763 to 75,059 ppm, Cd contents ranging from 1072 to 1362 ppm, and Mn contents ranging from 116 to 133 ppm (Fig. 11A). The SXRF elemental mappings revealed that Zn, S, Cd, Fe, and Mn are heterogeneously distributed (Fig. 11B-F; Niu et al., 2024). Zinc and S show slightly similar trends in elemental signal changes (Fig. 11B, C). Cadmium, Fe, and Mn display spatially correlated distributions, as evidenced by their prominent signals in H1 sphalerite, which gradually decrease in H2, H4, and H5 sphalerite, respectively (Fig. 11B-F). Notably, the Cd signal in H2 sphalerite is more pronounced than that in H1 sphalerite (Fig. 11E). The seven K-edge spectra obtained from the four colored sphalerite domains exhibit similar spectral profiles, with pre-edges located at the same position of 7112 eV (Fig. 11G, H).

# 6. Discussion

## 6.1. Distribution characteristics of Cd, Fe and Mn in sphalerite

The distributions of Cd, Fe and Mn in sphalerite are sometimes correlated in element maps, particularly in colloform and rhythmic sphalerite (e.g., Pfaff et al., 2011; Gagnevin et al., 2014), yet highly uncorrelated in some Cd-rich and Mn-rich sphalerite (Bernardini et al., 2004; Ye et al., 2011). This discrepancy suggests that the relationships among Cd, Fe and Mn in sphalerite remain incompletely understood. In this study, the strong inverse relationship between Fe and Zn signals indicates that $Fe^{2+} \rightarrow Zn^{2+}$ substitution is a dominate substitution in most cases (Fig. 8B, D, G, I). Iron and Mn signals exhibit positive correlations in both Huize and Maoping sphalerites (Fig. 9E, G; Fig. 10E, G). This relationship is evident across sphalerites of varying colors, where an increase in Fe signal intensity corresponds to a proportional increase in Mn signal intensity, particularly in the Synchrotron μ-XRF images (Fig. 11D, F). For Cd, its signal intensity is higher in H2 and H4 sphalerites compared to in H1 sphalerite from Huize (Fig. 9I). Similarly, in Maoping sphalerites, the highest Cd signal intensity is observed in M2 and M3 domains, while the lowest occurs in M1 (Fig. 10I). Synchrotron μ-XRF images also indicate that Cd is mostly enriched in H2 sphalerite, followed by H1, H4, and H5 sphalerite at Huize (Fig. 11E). Overall, along the sequences H5 → H4 → H2 → H1 and M3 → M2 → M1, the signal intensities of Cd, Fe, and Mn gradually increase, but Cd signals decrease significantly in H1 and M1 sphalerite (Fig. 9E, G, I; Fig. 10E, G, I). Thus, based on the elemental images, Cd, Fe, and Mn in sphalerite exhibit a strong coupling relationship in their signal distributions. This observation may be attributed to potential specific element substitutions within sphalerite, which will be further explored in the following discussion.
<figure><img src="image_9.png" /><figcaption>**Fig. 8.** Transmitted light image and µ-XRF element mappings of typical sphalerite samples with different colors from the Huize and Maoping deposits. (A-E) H1, H2, H5 and H6 sphalerite associated with pyrite in Sample 1 (KS-1740-19) from the Huize deposit and its µ-XRF element mappings of Zn, S, Fe and Pb; (F-J) massive M1 and M2 sphalerite, along with small M4 and pyrite in Sample 2 (20MP-4-1) from the Maoping deposit and its µ-XRF element mappings of Zn, S, Fe and Pb.</figcaption></figure>
<figure><img src="image_10.png" /><figcaption>Fig. 9. (A, B) Transmitted light photograph of sample 1 (QL-1331-2) in the Huize deposit and analyzed region for LA-ICP-MS; (C-N) Element signal mappings of the analyzed region, including Zn, S, Fe, Cu, Mn, Ag, Cd, Ga, Ge, In, Sn and Sb.</figcaption></figure>

<figure><img src="image_11.png" /><figcaption>Fig. 10. (A, B) Transmitted light photograph of sample 2 (20MP-2-2) in the Maoping deposit and analyzed region for LA-ICP-MS; (C-N) Element signal mappings of the analyzed region, including Zn, S, Fe, Cu, Mn, Ag, Cd, Ga, Ge, In, Sn and Sb.</figcaption></figure>

## 6.2. Oxidation states and substitution mechanisms of Cd, Fe, and Mn in sphalerite

Cadmium and Mn in sphalerite typically occur in the +2 oxidation state, as suggested by element substitution mechanisms such as Cd²⁺ → Zn²⁺, Mn²⁺ → Zn²⁺, and Cd²⁺ + Mn²⁺ → 2Zn²⁺ (Cook et al., 2009; Ye et al., 2011; Niu et al., 2023). The pre-edge feature arises from the 1s → 3d electronic transition (Shulman et al., 1976). The Fe-K pre-edge characteristics in sphalerite can serve as indicators for determining the oxidation state of Fe, where Fe³⁺ typically results in a significantly narrower peak or splitting into two distinct peaks separated by approximately 4 eV (Munoz et al., 2013). Belissont et al. (2016) confirmed the presence of Fe²⁺ in sphalerite with 1.6–2.6 wt% Fe

contents via X-ray absorption near edge structure spectroscopy (µ-XANES). In this study, H1, H2, H3 and H4 sphalerite samples contain 1.2–10.8 wt% Fe and exhibit consistent Fe-K pre-edges positions and spectral shapes (Fig. 11H, Niu et al., 2024). Our findings indicate that Fe in sphalerite with Fe contents ranging from 1.2 to 10.8 wt% predominantly exists in the +2 oxidation state, with no detectable Fe³⁺ present.

Based on the discussion above, we conclude that Fe²⁺ → Zn²⁺ represents the most pivotal element substitution mechanism in Huize and Maoping sphalerites, thereby resulting in polychromes in sphalerite (Wright and Gale, 2010; Gagnevin et al., 2014). Moreover, fluctuations in Fe contents within sphalerite directly influence the distributions of Cd and Mn. Binary diagrams of Fe vs. Cd, Fe vs. Mn, and Cd vs. Mn for Huize and Maoping sphalerites are presented based on LA-ICP-MS data
<figure><img src="image_12.png" /><figcaption>**Fig. 11.** (A) Reflected light photograph of sphalerite and analyzed points in the Huize deposit (analyzed area from Fig. 7B; element contents from Niu et al., 2024). (B-F) Synchrotron µ-XRF maps of Zn, S, Cd, Fe, and Mn, showing the analyzed points for µ-XANES. (G, H) Normalized and pre-edge Fe K-edge spectra of Huize sphalerite.</figcaption></figure>

<figure><img src="image_13.png" /><figcaption>**Fig. 12.** (A-C) Binary diagrams of Fe and Cd, Fe and Mn, and Cd and Mn in Huize sphalerite (data from Niu et al., 2024); (D-F) Binary diagrams of Fe and Cd, Fe and Mn, and Cd and Mn in Maoping sphalerite (data from Niu et al., 2023).</figcaption></figure>
<figure><img src="image_14.png" /><figcaption>Fig. 13. Binary scatter plots of temperature (A, B) and sulfur fugacity (C, D) with Cd contents in Huize and Maoping sphalerite (data from Niu et al., 2023, Niu et al., 2024).</figcaption></figure>

(Fig. 12A-F; Niu et al., 2023, 2024). In Huize sphalerite, the Fe content ranging of 200 to 1200 µmol/g (1.1–6.7 wt%) exhibits a discernible linear correlation with Cd, and a Cd/Fe ratio approaching 0.025 indicates the substitution of 40Fe²⁺ + Cd²⁺ → Zn²⁺ (Fig. 12A). Notably, when Fe content exceeds 1200 µmol/g (~6.7 wt%), Cd content markedly decreases and exhibits a negative linear correlation with Fe content in sphalerite (Fig. 12A). The relationship between Fe and Mn also exhibits a strong linear correlation, with a Mn/Fe ratio of 0.004 for Fe contents ranging from 200 (1.1 wt%) to 600 (3.4 wt%) µmol/g and a Mn/Fe ratio of 0.0017 for Fe contents exceeding 600 µmol/g (Fig. 12B). The observations indicate two substitutions: 17Fe²⁺ + 10,000Mn²⁺ → 1001Zn²⁺ and 250Fe²⁺ + Mn²⁺ → 251Zn²⁺. Except for some H1 and H2 sphalerite, Cd and Mn show an inverse relationship in other colored sphalerite in Huize (Fig. 12C). In the Maoping deposit, the Fe content in M1 sphalerite has certain correlations with Cd, represented by the substitutions 1000Fe²⁺ + 17Cd²⁺ → 1017Zn²⁺ (200 µmol/g < Fe < 400 µmol/g) and 100Fe²⁺ + Cd²⁺ → 101Zn²⁺ (Fe > 400 µmol/g), respectively, on the basis of different Cd/Fe ratios (0.017 and 0.01) (Fig. 12D). The correlation between Fe and Mn suggests the presence of two additional substitutions in M1 sphalerite: 250Fe²⁺ + 3Mn²⁺ → 253Zn²⁺ and 1000Fe²⁺ + Mn²⁺ → 1001Zn²⁺ (Fig. 12E). The scatter plot of Cd and Mn contents reveals an inverse relationship across sphalerite of different colors in Maoping (Fig. 12F). Although the sphalerite lattice can accommodate various types of elements (e.g., Fe, Cd, Ge, Ga, Re, Tl, In, Sn, As, Mn, Cu, Pb, Se and Ag; Cook et al., 2009; Ye et al., 2011), only Cd, Fe, and Mn are common elements and can directly substitute for Zn²⁺ at the +2 valence state (Cd²⁺ → Zn²⁺ and Mn²⁺ → Zn²⁺). Consequently, in Fe-poor condition, Cd and Mn may compete for incorporation into the sphalerite lattice. This competitive behavior could potentially account for the observed inverse relationship between Cd and Mn concentrations observed in Fe-poor sphalerite in this study.

Therefore, in Huize (H1, H2, H4 and H5) and Maoping (M1, M2, and

M3) sphalerite, Cd and Mn can be incorporated into the sphalerite crystal lattice in association with varying Fe contents, summarized by Cd²⁺ + nFe²⁺ → (n + 1)Zn²⁺ and Mn²⁺ + nFe²⁺ → (n + 1)Zn²⁺. Furthermore, in sphalerite with very low Fe contents (e.g., H3 and H6; M4 and M5), Cd and Mn are incorporated primarily through the direct substitutions: Cd²⁺ → Zn²⁺ and Mn²⁺ → Zn²⁺ (Fig. 12A, B, D, E).

## 6.3. Implications for Cd enrichment and exploration

Sphalerite serves as a significant host mineral for Cd, with its content potentially reaching several weight percent, such as in the Jinding deposit (China) and Red Dog deposit (USA) (Kelley et al., 2004; Cook et al., 2009; Ye et al., 2011). However, the reported Cd contents of up to 6.5 wt % in sphalerite cannot be conclusively attributed to solid-solution incorporation, as they may be influenced by the presence of nanoscale Cd-bearing minerals, such as greenockite (CdS) in the Jinding and Niujiaotang Cd-Pb-Zn deposits (Ye et al., 2011; Duan et al., 2023).

Previous studies have demonstrated that high temperature plays a significant role in promoting Cd enrichment in sphalerite (Schwartz, 2000; Ye et al., 2011; Wen et al., 2016; Wang et al., 2024). However, the enrichment of Cd in low temperature sphalerite has also been extensively documented (Wen et al., 2019; Xu et al., 2021; Shu et al., 2024). Consequently, the mechanisms responsible for Cd enrichment in sphalerite remain poorly understood. In the pyrrhotite-free sulfides system, the Fe/Zn ratio in sphalerite can be utilized to estimate the minimum fluid temperatures during precipitation (Keith et al., 2014):

$$T = (\text{Fe}/\text{Zn}_{\text{sphalerite}} + 0.2953)/0.013$$

where T is expressed in degrees Celsius (°C). Buffered by pyrite, the FeS activity in sphalerite can be used to estimate the sulfur fugacity of the ore-forming fluid (Frenzel et al. 2021), using the equation below:
<figure><img src="image_15.png" /></figure>

<figure><img src="image_16.png" /><figcaption>Fig. 14. (A) Ternary diagrams of normalized Cd, Fe, and Mn contents in Huize and Maoping sphalerite (data from Niu et al., 2023, 2024). (B) Coupling relationships between the contents of Cd, Fe, and Mn in sphalerite controlled by temperature and sulfur fugacity.</figcaption></figure>

$$log_{10}fS_2 = -2log_{10}[Fe_{(sp)}] - 15000/T + 14.5$$

where the $FeS_{(sp)}$ represents the FeS activity in sphalerite and T is in degree Celsius (°C). According to the empirical formula above, the formation temperature and sulfur fugacity of sphalerite were calculated, and binary diagrams involving Cd are presented in Fig. 13A-D. In addition, a ternary diagram of the Fe (Fe/100), Cd (Cd/10) and Mn contents in the Huize and Maoping sphalerite was constructed to illustrate their relationships (Fig. 14A).

In the temperature range of 240–320 °C, higher temperatures promote Cd enrichment in sphalerite in the form of $Cd^{2+}+nFe^{2+} \rightarrow (n + 1)Zn^{2+}$, as observed in H2, H4, H5, and part of H1 sphalerite in Huize and M1 and M2 sphalerite in Maoping (Fig. 12A, D; Fig. 13A, B; Fig. 14A; Wang et al., 2024). However, when temperature exceeds 320 °C, Cd enrichment in sphalerite is suppressed, as observed in H1 sphalerite (Fig. 12A; Fig. 13A, B). In some low-temperature sphalerite, the Cd content exhibits considerable variability, yet no clear linear correlation with Fe content is observed; for example, H3 and H6 in Huize and M4 and M5 in Maoping (Fig. 13A, B; Fig. 14A). Overall, the influence of temperature on Cd enrichment in sphalerite is primarily associated with two Cd substitutions incorporation into sphalerite. At higher temperatures (>240 °C), increased Fe incorporation into sphalerite facilitates Cd enrichment via $Cd^{2+}+nFe^{2+} \rightarrow (n + 1)Zn^{2+}$ (Fig. 12A, D; Bonnet et al., 2014). In contrast, low temperature inhibits Fe incorporation into sphalerite, thereby promoting Cd enrichment in sphalerite via $Cd^{2+} \rightarrow Zn^{2+}$ (Fig. 12A, D; Belissont et al., 2016; Cook et al., 2009). Notably, no apparent correlation between is observed sulfur fugacity and the Cd

content in sphalerite; both high and low sulfur fugacity can lead to Cd enrichment (Fig. 13C, D). Overall, temperature plays a crucial role in the Cd enrichment, as both high and low temperatures can lead to the accumulation of Cd in sphalerite. However, the potential impact of sulfur fugacity on Cd enrichment remains unclear.

Cadmium in Pb-Zn deposits primarily occurs in two forms: as independent minerals (e.g., CdS) and through element substitution into sphalerite (Ye et al., 2012; Duan et al., 2023). Compared to Cd-bearing independent minerals, sphalerite, the dominant mineral in Pb-Zn deposits, can incorporate up to several wt. % Cd, making it the primary focus for studying Cd enrichment and exploration (Cook et al., 2009; Pfaff et al., 2011; Ye et al., 2011). In this study, Cd is predominantly enriched in two types of sphalerites: (1) Fe-poor sphalerite, which forms during the latest stages and contains negligible Fe; and (2) Fe-rich sphalerite, which forms at earlier stages, particularly under formation temperatures around 300 °C. Consequently, in the Pb-Zn deposits formed at higher temperatures, Cd undergoes dual enrichment in both Fe-rich and Fe-poor sphalerite, leading to greater preservation of Cd resources. Therefore, the formation temperature of Pb-Zn deposits serves as a critical indicator for evaluating Cd resource potential and its enrichment degree.

## 7. Conclusions

(1) Iron in sphalerite is present in the divalent oxidation state ($Fe^{2+}$), with concentrations ranging from 1.2 to 10.8 wt%.

(2) In Fe-rich sphalerite ($Fe > 1.2$ wt%), the following substitution mechanisms involving Cd, Fe, and Mn are identified: $Cd^{2+}+nFe^{2+} \rightarrow (n + 1)Zn^{2+}$ and $Mn^{2+}+nFe^{2+} \rightarrow (n + 1)Zn^{2+}$. In Fe-poor sphalerite, Cd and Mn can directly substitute for Zn within the crystal structure ($Cd^{2+} \rightarrow Zn^{2+}$ and $Mn^{2+} \rightarrow Zn^{2+}$), and their concentrations exhibit an inverse correlation.

(3) Both high- (>300 °C) and low (<240 °C)-temperature sphalerite can facilitate Cd enrichment, suggesting that Pb-Zn deposits formed under higher temperature conditions (>300 °C) are more favorable for two-stage Cd enrichment in sphalerite and demonstrate enhanced potential for cadmium resource preservation.

## Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

## Acknowledgments

We appreciate the Lucia Beamline of the French National Synchrotron Radiation (SOLEIL Synchrotron). This study is financially supported by grants from the National Natural Science Foundation of China (42321001, 42503023), the Expert Workstation in Geological Team 308, Yunnan Bureau of Nonferrous Geology, Kunming (202405AF140108), the State Key Laboratory of Geological Processes and Mineral Resources in China University of Geosciences (Wuhan) (MSFGPMR2025-302), and the Program of the China Scholarships Council (No. 202106410073).

## Appendix A. Supplementary data

Supplementary data to this article can be found online at https://doi.org/10.1016/j.oregeorev.2025.106880.

## Data availability

All the data are available in the manuscript as Tables and are also available from the corresponding author upon request.
## References

Bao, Z.W., Li, Q., Wang, C.Y., 2017. Metal source of giant Huize Zn-Pb deposit in SW China: New constraints from in situ Pb isotopic compositions of galena. Ore Geol. Rev. 91, 824–836.

Bauer, M.E., Burisch, M., Ostendorf, J., Krause, J., Frenzel, M., Seifert, T., Gutzmer, J., 2019. Trace element geochemistry of sphalerite in contrasting hydrothermal fluid systems of the Freiberg district, Germany: insights from LA-ICP-MS analysis, near-infrared light microthermometry of sphalerite-hosted fluid inclusions, and sulfur isotope geochemistry. Miner. Deposita 54, 237–262.

Belissont, R., Boiron, M.C., Luais, B., Cathelineau, M., 2014. LA-ICP-MS analysis of minor and trace elements and bulk Ge isotopes in zoned Ge-rich sphalerite from the Noilhac-Saint-Salvy deposit (France): insights into incorporation mechanisms and ore deposition process. Geochim. Cosmochim. Acta 126, 518–540.

Belissont, R., Munoz, M., Boiron, M.C., Luais, B., Mathon, O., 2016. Distribution and oxidation state of Ge, Cu and Fe in sphalerite by l-XRF and K-edge l-XANES: insights into Ge incorporation, partitioning and isotopic fractionation. Geochim. Cosmoc. Acta 177, 298–314.

Bernardini, G.P., Borgheresi, M., Cipriani, C., Di Benedetto, F., Romanelli, M., 2004. Mn distribution in sphalerite: an EPR study. Phys. Chem. Miner. 31, 80–84.

Bonnet, J., Mosser-Ruck, R., André-Mayer, A.S., Jean, C., Bailly, L., 2014. Germanium distribution in sphalerite from north-east America MVT deposits: a multiscale study. Acta Geol. Sin. 88, 437–439.

Gagnevin, D., Menuge, J.F., Kronz, A., Barrie, C., Boyce, A.J., 2014. Minor elements in layered sphalerite as a record of fluid origin, mixing, and crystallization in the Navan Zn-Pb ore deposit, Ireland. Econ. Geol. 109, 1513–1528.

Chen, M.X., Zheng, Y., Chen, X., Yu, P.P., Zhang, G.Z., Wu, Y.H., Huang, Y., Wang, X.L., Lin, Z.W., 2024. High-Cd sphalerite in the Pangxidong Pb-Zn-Ag deposit (Yunkai Doman, South China): Insight for physicochemical condition of orogenic-type deposit. Ore Geol. Rev. 167, 105974.

Cook, N.J., Ciobanu, C.L., Pring, A., Skinner, W., Shimizu, M., Danyushevsky, L., Saini-Eidukat, B., Melcher, F., 2009. Trace and minor elements in sphalerite: a LA-ICP-MS study. Geochim. Cosmochim. Acta 73, 4761–4791.

Debret, B., Andreani, M., Munoz, M., Bolfan-Casanova, N., Carlut, J., Nicollet, C., Schwartz, S., Trcera, N., 2014. Evolution of Fe redox state in serpentine during subduction. Earth Planet. Sci. Lett. 400, 206–218.

Duan, H.Y., Wang, C.M., Hu, R., Zhu, J.X., Deng, J., 2023. Supernormal enrichment of cadmium in sphalerite via coupled dissolution-reprecipitation process. Commun. Earth Environ. 4, 356.

Frenzel, M., Hrisch, T., Gutzmer, J., 2016. Gallium, germanium, indium, and other trace and minor elements in sphalerite as a function of deposit type-a meta-analysis. Ore Geol. Rev. 76, 52–72.

Frenzel, M., Voudouris, P., Cook, N.J., Ciobanu, C.L., Gilbert, S., Wade, B.P., 2021. Evolution of a hydrothermal ore-forming system recorded by sulfide mineral chemistry: a case study from the Plaka Pb-Zn-Ag deposit, Lavron, Greece. Miner. Deposita 57, 417–438.

Fougerouse, D., Cugerone, A., Reddy, S.M., Luo, K., Motto-Ros, V., 2023. Nanoscale distribution of Ge in Cu-rich sphalerite. Geochim. Cosmochim. Acta 346, 223–230.

Han, R.S., Chen, J., Wang, F.M., Wang, X.K., Li, Y., 2015. Analysis of metal-element association halos within fault zones for the exploration of concealed ore-bodies — a case study of the Qilinchang Zn-Pb-(Ag-Ge) deposit in the Huize mine district, northeastern Yunnan, China. J. Geochem. Explor. 159, 62–78.

Han, R.S., Liu, C.Q., Huang, Z.L., Chen, J., Ma, D.Y., Lei, L., Ma, G.S., 2007. Geological features and origin of the Huize carbonate-hosted Zn-Pb-(Ag) district, Yunnan, South China. Ore Geol. Rev. 31, 360–383.

Han, R.S., Zhang, Y., Wang, F., Wu, P., Qiu, W.L., Li, W.Y., 2019. Metallogenic mechanism and location prediction of concealed ore bodies of Germanium-rich silver-zinc-lead deposits in the polymetallic deposit concentrated district in Beijing, China Science Press, Northeastern Yunnan, China, pp. 1-510 (in Chinese).

He, Q., Xiao, L., Balta, B., Gao, R., Chen, Y.J., 2010. Variety and complexity of the Late-Permian Emeishan basalts: Reappraisal of plume-lithosphere interaction processes. Lithos 119, 91–107.

Höll, R., Kling, M., Schroll, E., 2007. Metallogenesis of germanium—A review. Ore Geol. Rev. 30, 145–180.

Huang, Z.L., Chen, J., Han, R.S., Li, W.B., Liu, C.Q., Zhang, Z.L., Ma, D.Y., Gao, D.R., Yang, H.L., 2004. Geochemistry and ore-formation of the Huize giant lead-zinc deposit, Yunnan, Province, China: Discussion on the relationship between Emeishan flood basalts and lead-zinc mineralization. Geological Publishing House, Beijing (in Chinese).

Janots, E., Bernier, F., Brunet, F., Munoz, M., Trcera, N., Berger, A., Lanson, M., 2015. Ce (III) and Ce(IV) (re)distribution and fractionation in a laterite profile from Madagascar: Insights from in situ XANES spectroscopy at the CeL-III-edge. Geochim. Cosmochim. Acta 153, 134–148.

Jiang, S.Y., Wang, W., Su, H.M., 2023. Super-enrichment mechanisms of strategic critical metal deposits: current understanding and future perspectives. J. Earth Sci. 34 (4), 1295–1298.

Keith, M., Haase, K.M., Schwarz-Schamperla, U., Klemd, R., Petersen, S., Bach, W., 2014. Effects of temperature, sulfur, and oxygen fugacity on the composition of sphalerite from submarine hydrothermal vents. Geology 42, 699–702.

Kelley, K.D., Leach, D.L., Johnson, C.A., Clark, J.L., Fayek, M., Slack, J.F., Anderson, M., Ayuso, R.A., Ridley, W.I., 2004. Textural, compositional, and sulfur isotope variations of sulfide minerals in the Red Dog Zn-Pb-Ag deposit, Brooks Range, Alaska: implications for ore formation. Econ. Geol. 99, 1509–1532.

Leach, D.L., Sangster, D.F., 1993. Mississippi Valley-type lead-zinc deposits. Geological Association of Canada Special Paper 40, 289–314.

Leach, D.L., Sangster, D.F., Kelley, K.D., 2005. Sediment-hosted lead-zinc deposits: a global perspective. Economic Geology 100th Anniversary 561–607.

Leach, D.L., Song, Y.C., 2019. Sediment-hosted zinc-lead and copper deposits in China. SEG Special Publications 22, 325–409.

Liu, W.H., Mei, Y., Etschmann, B., Glenn, M., MacRae, C.M., Spinks, S.C., Ryan, C.G., Brugger, J., Paterson, D.J., 2023. Germanium speciation in experimental and natural sphalerite: Implications for critical metal enrichment in hydrothermal Zn-Pb ores. Geochim. Cosmochim. Acta 342, 198–214.

Luo, K., Cugerone, A., Fougerouse, D., Zhou, J.X., Xian, H.Y., Yang, Y.P., Saxey, D.W., Motto-Ros, V., Sun, X., Rickard, W.D.A., Reddy, S.M., 2025. Rapid crystal growth promotes the precipitation of nanoscale fluid inclusions rich in halogens and metals in colloform sphalerite. Geochim. Cosmochim. Acta 398, 119–138.

Maghfouri, S., Hosseinzadeh, M.R., Choulet, F., 2020. Supergene nonsulfide Zn-Pb mineralization in the Mehdiabad world-class sub-seafloor replacement SEDEX-type deposit, Iran. Int. J. Earth Sci. 109, 2531–2555.

Marsh, E.E., Hitzman, M.W., Leach, D.L., 2016 Critical elements in sediment-hosted deposits (clastic-dominated Zn-Pb-Ag, Mississippi Valley-Type Zn-Pb, sedimentary rock-hosted stratiform Cu, and carbonate-hosted polymetallic deposits): A review: Chapter 12. Rev. Econ. Geol. 18, 307-321.

Meng, Y.M., Hu, R.Z., Huang, X.W., Gao, J.F., Sasseville, C., 2019. The origin of the carbonate-hosted Huize Zn-Pb-Ag deposit, Yunnan province, SW China: constraints from the trace element and sulfur isotopic compositions of pyrite. Mineral. Petrol. 113, 369–391.

Munoz, M., Vidal, O., Marcaillou, C., Pascarelli, S., Mathon, O., Farges, F., 2013. Iron oxidation state in phyllosilicate single crystals using Fe-K pre-edge and XANES spectroscopy: effects of the linear polarization of the synchrotron X-ray beam. Am. Mineral. 98 (7), 1187–1197.

Ning, S., Wang, F., Xue, W., Zhou, T., 2017. Geochemistry of the Baoshan pluton in the Tongling region of the lower Yangtze River Belt. Geochimica 46, 397–412 in Chinese with English abstract.

Niu, P.P., Jiang, S.Y., Munoz, M., 2023. Two-stage enrichment of germanium in the giant Maoping MVT Pb-Zn deposit, southwestern China: Constraints from in situ analysis of multicolor sphalerites. Ore Geol. Rev. 157, 105421.

Niu, P.P., Munoz, M., Mathon, O., Xiong, S.F., Jiang, S.Y., 2024. Mechanism of germanium enrichment in the world-class Huize MVT Pb-Zn deposit, southwestern China. Miner. Deposita 59, 995.

Oyebamiji, A., Falae, P., Zafar, T., Rehman, H.U., Oguntuase, M., 2023. Genesis of the Qilinchang Pb-Zn deposit, southwestern China: evidence from mineralogy, trace elements systematics and S-Pb isotopic characteristics of sphalerite. Appl. Geochem. 148, 105545.

Paradis, S., Petts, D., Simandl, G.J., Sharpe, R., Hamilton, T.S., Fayek, M., Jackson, S.E., 2023. Impact of deformation and metamorphism on sphalerite chemistry - element mapping of sphalerite in carbonate-hosted zn-pb sulfide deposits of the Kootenay arc, southern British Columbia. Canada and Northeastern Washington, USA: Ore Geology Reviews 158, 105482.

Pfaff, K., Koenig, A., Wenzel, T., Ridley, I., Hildebrandt, L.H., Leach, D.L., Markl, G., 2011. Trace and minor element variations and sulfur isotopes in crystalline and colloform ZnS: Incorporation mechanisms and implications for their genesis. Chemical Geology 286, 118-134.

Qiu, Z.J., Fan, H.R., Tomkins, A.G., Brugger, J., Etschmann, B., Liu, X., Xing, Y.L., Hu, Y., 2021. Insights into salty metamorphic fluid evolution from scapolite in the Trans-North China Orogen: Implication for ore genesis. Geochim. Cosmochim. Acta 293, 256–276.

Ravel, B., Newville, M., 2005. ATHENA, ARTEMIS, HEP ESTUS: data analysis for X-ray absorption spectroscopy using IFEFFIT. J. Synchrotron Radiat. 12, 537–541.

Sarjoughian, F., Habibi, I., Lentz, D.R., Azizi, H., Esna-Ashari, A., 2020. Magnetite compositions from the Baba Ali iron deposit in the Sanandaj-Sirjan zone, western Iran: Implications for ore genesis. Ore Geol. Rev. 126, 103728.

Schwartz, M.O., 2000. Cadmium in Zinc deposits: Economic Geology of a Polluting Element. Int. Geol. Rev. 42 (5), 445–469.

Shellnutt, J.G., 2014. The Emeishan large igneous province: a synthesis. Geosci. Front. 5, 369–394.

Shu, L.H., Chen, X., Yu, P.P., Huang, Y., Wang, X.L., Li, R.J., Tan, Z.J., Chen, M.X., Zheng, Y., 2024. Oxidative fluids facilitate Cd enrichment in a magmatic-hydrothermal system: an example from the Kangjiawan Zn-Pb-Zn polymetallic deposit, South China. Ore Geol. Rev. 165, 105926.

Shulman, R.G., Yafet, Y., Eisenberger, P., Blumberg, W.E., 1976. Observation and interpretation of Xray absorption edges in iron compounds and proteins. Proc. Natl. Acad. Sci. 73, 1384–1388.

Solé, V.A., Papillon, E., Cotte, M., Walter, Ph., Susini, J., 2007. A multiplatform code for the analysis of energy-dispersive X-ray fluorescence spectra. Spectrochim. Acta B 62, 63–68.

Sun, G.T., Zhou, J.X., Cugerone, A., Zhou, M.F., Zhou, L.L., 2023. Germanium-rich nanoparticles in Cu-poor sphalerite: a new mechanism for Ge enrichment. Geol. Soc. Am. Bull. 136 (7–8), 2891–2905.

Tang, Q.Y., Li, C.S., Ripley, E.M., Bao, J., Su, T.B., Xu, S.H., 2021. Sr-Nd-Hf-O isotope constraints on crustal contamination and mantle source variation of three Fe-Ti-V oxide ore deposits in the Emeishan large igneous province. Geochim. Cosmochim. Acta 292, 364–381.

Vantelon, D., Trcera, N., Roy, D., Moreno, T., Mailly, D., Guilet, S., Metchalkov, E., Delmotte, F., Lassalle, B., Lagarde, P., Flank, A.M., 2016. The LUCIA beamline at SOLEIL. J. Synchrotron Radiat. 23, 635–640.

Wang, C.M., Deng, J., Carranza, E.J.M., Lai, X.R., 2014. Nature, diversity and temporal-spatial distributions of sediment-hosted Pb-Zn deposits in China. Ore Geol. Rev. 56, 327–351.
Wang, L., Zhang, Y., Han, R.S., Li, X.D., 2023. LA-ICP-MS analyses of trace elements in zoned sphalerite: a study from the Maoping carbonate-hosted Pb-Zn(-Ge) deposit, southwest China. Ore Geol. Rev. 157, 105468.

Wang, X.H., Zheng, Y., Yu, P.P., Chen, X., Wu, Y.H., Huang, Y., Long, L.J., Shu, L.H., Chen, M.X., Guo, L.X., 2024. Temperature as a major control on Cd enrichment in a skarn system: a case study of the Yiliu Pb-Zn-As deposit, South China. Ore Geol. Rev. 165, 105920.

Wang, X.T., Shao, L.Y., Eriksson, K.A., Yan, Z.M., Wang, J.M., Li, H., Zhou, R.X., Lu, J., 2020. Evolution of a plume-influenced source-to-sink system: an example from the coupled central Emeishan large igneous province and adjacent western Yangtze cratonic basin in the Late Permian, SW China. Earth Sci. Rev. 207, 103224.

Wei, A.Y., Xue, C.D., Xiang, K., Li, J., Liao, C., Akhter, Q.J., 2015. The ore-forming process of the Maoping Pb-Zn deposit, northeastern Yunnan, China: Constraints from cathodoluminescence (CL) petrography of hydrothermal dolomite. Ore Geol. Rev. 70, 562–577.

Wei, C., Ye, L., Hu, Y.S., Huang, Z.L., Danyushevsky, L., Wang, H.Y., 2021. LA-ICP-MS analyses of trace elements in base metal sulfides from carbonate-hosted Zn-Pb deposits, South China: a case study of the Maoping deposit. Ore Geol. Rev. 130, 103945.

Wen, H.J., Zhu, C.W., Zhang, Y.X., Cloquet, C., Fan, H.F., Fu, S.H., 2016. Zn/Cd ratios and cadmium isotope evidence for the classification of lead-zinc deposits. Sci. Rep. 6 (1), 25273.

Wen, H.J., Zhou, Z.B., Zhu, C.W., Luo, C.G., Wang, D.Z., Du, S.J., Li, X.F., Chen, M.H., Li, H.Y., 2019. Critical scientific issues of super-enrichment of dispersed metals. Acta Petrol. Sin. 35, 3271–3291 in Chinese with English abstract.

Wen, H.J., Zhu, C.W., Du, S.J., Fan, Y., Luo, C.G., 2020. Gallium (Ga), germanium (Ge), thallium (TI) and cadmium (Cd) resources in China. Chin. Sci. Bull. 65, 3688–3699 in Chinese with English abstract.

Wright, K., Gale, J.D., 2010. A first principles study of the distribution of iron in sphalerite. Geochim. Cosmochim. Acta 74, 3514–3520.

Wu, T., Huang, Z.L., He, Y.F., Yang, M., Fan, H.F., Chen, W., Ye, L., Hu, Y.S., Xiang, Z.Z., Lai, C.K., 2021. Metal source and ore-forming process of the Maoping carbonate-hosted Pb-Zn deposit in Yunnan, SW China: evidence from deposit geology and sphalerite Pb-Zn-Cd isotopes. Ore Geol. Rev. 135, 104214.

Wu, Y., Kong, Z.G., Chen, M.H., Zhang, C.Q., Cao, L., Tang, Y.J., Yuan, X., Zhang, P., 2019. Trace elements in sphalerites from the Mississippi Valley-type lead-zinc deposits around the margins of Yangtze Block and its geological implications: a LA-ICPMS study. Acta Petrol. Sin. 35 (11), 3443–3460 in Chinese with English abstract.

Xiang, Z.Z., Zhou, J.X., Luo, K., 2020. New insights into the multi-layer metallogenesis of carbonated-hosted epigenetic Pb-Zn deposits: a case study of the Maoping Pb-Zn deposit, South China. Ore Geol. Rev. 122, 103538.

Xiao, X., Zhou, T.F., White, N.C., Zhang, L.J., Fan, Y., Wang, F.Y., Chen, X.F., 2018. The formation and trace elements of garnet in the skarn zone from the Xinqiao Cu-S-Fe-

Au deposit, Tongling ore district, Anhui Province, Eastern China. Lithos 302–303, 467–479.

Xu, C., Zhong, H., Hu, R.Z., Wen, H.J., Zhu, W.G., Bai, Z.J., Fan, H.F., Li, F.F., Zhou, T., 2020. Sources and ore-forming fluid pathways of carbonate-hosted Pb-Zn deposits in Southwest China: implications of Pb-Zn-S-Cd isotopic compositions. Miner. Deposita 55, 491–513.

Xu, J., Cook, N.J., Ciobanu, C.L., Li, X.F., Kontonikas-Charos, A., Gilbert, S., Lv, Y.H., 2021. Indium distribution in sphalerite from sulfide-oxide-silicate skarn assemblages: a case study of the Dulong Zn-Sn-In deposit, Southwest China. Miner. Deposita 56, 307–324.

Yan, L., Fan, Y., Huang, J., Zou, T., Wang, F.Y., Zhou, T.F., 2025. Formation of nano-CdS solid solution: a mechanism for Cd enrichment in sphalerite. Am. Mineral. 110, 1186–1196.

Ye, L., Cheng, Z.T., Pan, Z.P., Liu, T.G., Gao, W., 2010. A study on the distribution characteristics and existing states of cadmium in the Jinding Pb-Zn deposit, Yunnan Province, China. Acta Geochim. 29, 319–325.

Ye, L., Cook, N.J., Ciobanu, C.L., Liu, Y.P., Zhang, Q., Liu, T.G., Gao, W., Yang, Y.L., Danyushevskiy, L., 2011. Trace and minor elements in sphalerite from base metal deposits in South China: a LA-ICPMS study. Ore Geol. Rev. 39, 188–217.

Ye, L., Cook, N.J., Liu, T.G., Ciobanu, C.L., Gao, W., Yang, Y.L., 2012. The Niujiaotang Cd-rich zinc deposit, Duyun, Guizhou province, southwest China: ore genesis and mechanisms of cadmium concentration. Miner. Deposita 47, 683–700.

Yin, R.S., Feng, X.B., Li, Z.G., Zhang, Q., Bi, X.W., Li, G.H., Liu, J.L., Zhu, J.J., Wang, J.X., 2012. Metallogeny and environmental impact of Hg in Zn deposits in China. Appl. Geochem. 27, 151–160.

Zhang, C.Q., Wu, Y., Hou, L., Mao, J.W., 2015. Geodynamic setting of mineralization of Mississippi Valley-type deposits in world-class Sichuan-Yunnan-Guizhou Zn-Pb triangle, southwest China: Implications from age-dating studies in the past decade and the Sm-Nd age of Jinshachang deposit. J. Asian Earth Sci. 103, 103–114.

Zhao, W.C., Zhu, X.Y., Jiang, B.B., Zhao, D.S., 2023. Genesis of the carbonate-hosted zinc-lead deposits in the southwestern Yangtze Craton, SW China: insights from the Maoping deposit. J. Geochem. Explor. 250, 107234.

Zhu, C.W., Wen, H.J., Zhang, Y.X., Fu, S.H., Fan, H.F., Cloquet, C., 2017. Cadmium isotope fractionation in the Fule Mississippi Valley-type deposit, Southwest China. Miner. Deposita 52, 675–686.

Zhu, C.W., Wang, J., Zhang, J.W., Chen, X.C., Fan, H.F., Zhang, Y.X., Yang, T., Wen, H.J., 2020. Isotope geochemistry of Zn, Pb and S in the Ediacaran strata hosted Zn-Pb deposits in Southwest China. Ore Geol. Rev. 117, 103274.

Zhou, J.X., Huang, Z.L., Zhou, M.F., Zhu, X.K., Muchez, P., 2014. Zinc, sulfur and lead isotopic variations in carbonate-hosted Pb-Zn sulfide deposits, southwest China. Ore Geol. Rev. 58, 41–54.

Zhou, J.X., Xiang, Z.Z., Zhou, M.F., Feng, Y.X., Luo, K., Huang, Z.L., Wu, T., 2018. The giant Upper Yangtze Pb-Zn province in SW China: Reviews, new advances and a new genetic model. J. Asian Earth Sci. 154, 280–315.