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Article

Metallogenic Mechanisms of the Lower Triassic Dongping Sedimentary Manganese Deposit in the South China Block: Mineralogical and Geochemical Evidence

by
Rong-Zhi Li
1,
Sha Jiang
1,2,
Peng Long
1,
Tao Long
1,
Da-Qing Ding
1,
Ling-Nan Zhao
3,
Yi Zhang
4 and
Qin Huang
3,*
1
China Metallurgical Geology Bureau of Geological Prospecting Institute of Guangxi, Nanning 530022, China
2
China Metallurgical Geology Bureau, Beijing 100025, China
3
Guangxi Laboratory on the Study of Coral Reefs in the South China Sea, Coral Reef Research Center of China, School of Marine Sciences, Guangxi University, Nanning 530004, China
4
State Key Laboratory of Coal Mine Disaster Dynamics and Control, School of Resources and Safety Engineering, Chongqing University, Chongqing 400044, China
*
Author to whom correspondence should be addressed.
Minerals 2025, 15(8), 847; https://doi.org/10.3390/min15080847 (registering DOI)
Submission received: 6 July 2025 / Revised: 4 August 2025 / Accepted: 6 August 2025 / Published: 8 August 2025
(This article belongs to the Section Mineral Deposits)
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Abstract

The Dongping manganese (Mn) deposit, located within the Lower Triassic Shipao Formation of the Youjiang Basin, is one of South China’s most significant sedimentary Mn carbonate ore deposits. To resolve longstanding debates over its metallogenic pathway, we conducted integrated sedimentological, mineralogical, and geochemical analyses on three drill cores (ZK5101, ZK0301, and ZK1205) spanning the Mn ore body. X-ray diffraction and backscatter electron imaging reveal that the ores are dominated by kutnohorite, with subordinate quartz, calcite, dolomite, and minor sulfides. The low enrichment of U/Al, V/Al, and Mo/Al, as well as positive Ce anomalies, consistently suggest that Mn, in the form of oxides, was deposited in an oxic water column. Carbon isotope compositions of Mn carbonate ores (δ13CVPDB: −2.3 to −6.1‰) and their negative correlation with MnO suggest that Mn carbonate, predominantly kutnohorite, show a diagenetic reduction in pre-existing Mn oxides via organic-matter oxidation in anoxic sediments pore waters. Elemental discrimination diagramms (Mn-Fe-(Co+Ni+Cu) × 10 and Co/Zn vs. Co+Cu+Ni) uniformly point to a hydrothermal Mn source. We therefore propose that hydrothermal fluids supplied dissolved Mn2+ to an oxic slope-basin setting, precipitating initially as Mn oxides, which were subsequently transformed to Mn carbonates during early diagenesis. This model reconciles both the hydrothermal and sedimentary-diagenetic processes of the Dongping Mn deposit.

1. Introduction

Manganese (Mn) is an essential metal with wide-ranging applications, particularly in battery and steel manufacturing [1]. Globally, sedimentary Mn ore deposits, which are composed of Mn(II) carbonate minerals such as rhodochrosite, kutnohorite, and Mn-calcite, represent crucial terrestrial Mn resources and have persisted throughout Earth’s geological history [2,3,4,5,6]. The metallogenic mechanisms underlying sedimentary Mn deposit formation have been extensively studied, with previous studies proposing two primary models [2,7,8,9,10,11,12]. Traditional models emphasize the Mn precipitates as primary Mn oxides upon mixing with oxygenated waters, during sea level fluctuations or upwelling events, and then Mn oxides were reacted with reductants (e.g., organic matter, CH4, HS− and Fe2+) and transferred into Mn carbonate during the early diagenetic process [4,5,6,13,14]. Alternatively, a more recent model suggests that under persistently anoxic and alkaline conditions, dissolved Mn2+ can precipitate directly as Mn carbonates without passing through a Mn oxide intermediate [9,10,15,16,17,18]. This mechanism has been documented in modern redox-stratified lakes and proposed for several ancient Mn deposits where sedimentary conditions favored direct Mn carbonate precipitation [11,12,15,16,17,18]. In specific cases, Mn2+ released from hydrothermal activities can directly form Mn carbonate in suboxic continental margins, bypassing the need for precursor Mn oxides [9,10]. These two models have markedly different implications for redox conditions and metal precipitation pathway in ancient basins. Thus, the concept of presence of oxygenated bottom waters in ocean basins driving Mn oxides deposition is questioned, and major redox controls in sedimentary Mn mineralization would have to be critically reviewed.
The early Triassic Mn deposits belt, which is located in the southwest of Guangxi in the South China Block (SCB), occurs in the siliceous marlstone in the lower part of the Shipao Formation [19,20,21]. Typical large-scale sedimentary Mn carbonate deposits (more than 30 million tons) include the Dongping, Pingyao, Fuwan, and Liuyi [22,23]. These Mn deposits are dominantly Mn carbonate, including Ca-rhodochrosite, kutnohorite and Mn-calcite. The most important example of Mn carbonate deposit hosted by Shipao Formation is the Dongping Mn deposit with resources of approximately 200 million tons [24]. Previous studies suggested that the Dongping Mn mineralization has a hydrothermal origin [21], but precipitation mechanism of Mn carbonate ores have remained controversial. In particular, the proposal of the direct precipitation pathway has presented a significant challenge to the conventional sedimentary-diagenetic model for the Dongping Mn deposit [19,20,21,23,25]. Therefore, in order to constrain the genesis of the Dongping Mn deposit, three cores across the Mn-bearing basin were selected for our study. In this study, we present the comprehensive dataset that combines geological and mineralogical information with detailed geochemical analyses of the Dongping Mn ore deposit. Detailed sedimentological, stratigraphic, and geochemical analyses have been integrated to constrain the metal sources and precipitation pathway of Mn carbonate during the formation of the Dongping Mn deposit.

2. Geological Setting

The Youjiang Basin is situated at the tectonic junction between the Tethyan and Paleo-Pacific domains [26]. The Tethyan domain comprises several blocks, including the Sibumasu, Indochina, and Northern Qiangtang blocks, which were amalgamated through Paleo-Tethyan sutures, such as the Triassic Changning-Menglian and Jinshanjiang sutures [26]. In contrast, the Paleo-Pacific domain is characterized by significant Jurassic to Cretaceous magmatism and strata. The Jurassic strata are primarily composed of terrestrial clastic rocks and carbonates, whereas the Cretaceous sequences consist mainly of clastic rocks interbedded with mudstone, with local exposures of intermediate to acidic volcanic rocks [26]. The Youjiang basin also encompasses both the Gathaysia and Yangtze blocks, which were fused during the Neoproterozoic to form the South China Block. The basin is primarily dominated by Late Paleozoic to Early Mesozoic sedimentary stratums, with Precambrian strata exposed in the adjacent orogenic belts [27]. During the Late Devonian to Carboniferous, the Youjiang basin experienced continental rifting, associated with the spreading of the Paleo-Tethyan Ocean. This rifting initiated along a passive continental margin, resulting in the formation of several isolated carbonate platforms encased within basin sedimentary facies sequences. The transition from a passive to an active margin occurred in the late Permian to Triassic, corresponding to the subduction of the Paleo-Pacific Ocean [28,29]. During this period, a foreland basin developed along the southern margin of the Youjiang Basin, accompanied by the emplacement of igneous rocks with arc-like geochemical signatures.
The Triassic Mn metallogenic belt, located along the southwestern margin of the Youjiang basin, is one of China’s key regions for the formation of sedimentary Mn carbonate deposits. This metallogenic belt hosts a series of large-scale sedimentary Mn deposits, with the Dongping deposit serving as the most representative example of this metallogenic belt (Figure 1). The Triassic stratigraphy within the study area is broadly categorized into three depositional facies types: platform facies, platform-margin facies, and slope-basin facies. Platform facies are represented by carbonate-dominated sequences of the Lower Triassic Majiaoling and Beisi formations, and the Middle Triassic Banna and Lanmu formations. Platform-margin facies include the Lower Triassic Luolou Formation and parts of the Middle Triassic Banna and Lanmu formations, comprising mainly carbonate and argillaceous rocks. Slope-basin facies are defined by the Lower Triassic Shipao Formation, the Middle Triassic Baifeng Formation, and portions of the Lanmu Formation, consisting primarily of clastic sediments with minor intercalations of carbonate.
The Lower Triassic Shipao Formation conformably overlies the Upper Permian Linghao Formation and hosts the Mn-bearing rock series in its upper portion-commonly referred to as the “Dongping Member” [30] (Figure 2). Based on lithological assemblages, the strata underlying the Dongping Member can be subdivided into two informal sub-members [19,30]. The lower sub-member is composed predominantly of thin- to medium-bedded tuffaceous limestone, mudstone interbedded with siltstone, and silty mudstone, displaying well-developed horizontal bedding and lamination indicative of slope-basin depositional conditions. The upper sub-member consists of thin-bedded microcrystalline limestone, argillaceous limestone, banded and lenticular limestone interbedded with thin layers of mudstone and calcareous mudstone. Locally, this unit contains tuffaceous mudstone, microbialite, vermicular limestone, and clastic limestone. The presence of horizontal bedding, banded to lenticular structures, suggests deposition in a slope environment. Overlying the Dongping Member is the Middle Triassic Baifeng Formation, which is characterized by medium- to thin-bedded calcareous mudstone, mudstone, Mn-bearing mudstone, and tuffaceous mudstone, interbedded with minor siltstone and fine sandstone.
In the Dongping Mn deposit, the stratigraphic sequence comprises the Middle Permian Sidazhai Formation, the Upper Permian Linghao Formation, the Lower Triassic Shipao Formation, and the Middle Triassic Baifeng Formation (Figure 3) [19,21,22]. The Mn-bearing rock series, referred to as the Dongping Member, is composed primarily of gray, thin- to medium-bedded argillaceous Mn-bearing limestone, manganese mudstone, manganiferous limestone, tuffaceous limestone, tuffaceous mudstone, and Mn carbonate ore. The Dongping Member exhibits well-developed horizontal bedding and lamination and is interpreted to represent a deep-water slope-basin depositional environment. Stratigraphically, it is contemporaneous with, but facies-differentiated from, the upper Luolou and lower Beisi formations.
The Dongping Mn deposit is subdivided into several mining sections, including Dongmeng, Luli, Tuoren East, Tuoren West, Dinuo, Tuopa, Nazao, Nashe, and Hanliu (Figure 3). Structurally, the mining area is dominated by NE-SW trending folds and faults, with the Wushushan syncline, Dinuo anticline, and Dongmeng syncline serving as the principal ore-controlling structures [24]. While volcanic rocks are minimally developed in the region, a laterally continuous tuffaceous limestone conformably overlies the Mn-bearing rock series, with no evidence of contact alteration in adjacent host rocks. The Mn-bearing rock series ranges in thickness from 1 to 10 m. Additionally, minor diabase dikes intrude the Middle to Upper Permian strata in the southeastern portion of the mining area.
Stratigraphic profiling reveal that the Dongping Member attains its maximum thickness, ranging from 70 to 220 m, and locally up to 323.9 m, in the Dinuo, Luli, Tuoren West, and Tuoren East sections. In these areas, the cumulative thickness of Mn carbonate ore bodies is substantial (3–15 m), with Mn grades ranging from 10% to 20% and an average of approximately 11.8% (Figure 4). The ores display well-developed laminated, oolitic-oncolitic, and banded structures, with minor nodular structures (Figure 5). Eastward and westward from this central zone, the Dongping Member progressively thins and eventually pinches out (Figure 4). In the eastern Hanliu area, the thickness decreases to 37.37 m, further thinning to 16.59 m at Nabu, and disappearing near Naban. To the northwest, the sequence thins from 62.1 m in Liuzhao (Jiangcheng Town) to 16.49 m at Nagu, where it also pinches out. In lateral sections such as Nashe, Nazao, and Dongyu—flanking the Dinuo section—the number of manganese carbonate layers is significantly reduced, generally ranging from 0 to 3 m in thickness. The primary ore layers (II and IV) are discontinuous in these regions, and Mn grades are comparatively lower, ranging from 10% to 13%, with an average of 10.5%. Laminated structures dominate in these peripheral areas, with oolitic–oncolitic and nodular structures notably absent. In general, both the thickness and manganese enrichment of carbonate ore bodies are maximized in the central Dinuo, Luli, Tuoren West, and Tuoren East sections. Thickness and ore grade decrease eastward toward Hanliu, northeastward to Nazao, northwestward to Nashe, and westward toward Dongmeng, outlining a well-defined spatial zonation of Mn enrichment across the deposit.

3. Samples and Analytical Methods

Manganese ore samples were retrieved from three drill cores (ZK5101, ZK0301, and ZK1205), which are distributed laterally across the ore body. Core ZK1205 and ZK0301 are situated in the Dinuo unit, and ZK5101 in the Hanliu unit (Figure 4). A total of 40 samples, consisting of banded Mn carbonate ores from these three drill cores, were collected. No alteration signs were detected in any of the samples.
For mineralogical analysis, ten powdered samples from the same cores were examined using a Bruker D8 ADVANCE X-ray diffractometer (XRD) (Bruker, Tokyo, Japan) at the Laboratory for Coral Reef Studies, South China, Guangxi, Nanning. The analyses were conducted using Cu-Kα radiation (λ = 1.5406 Å) at 40 kV and 40 mA, with a 2θ scan range from 5° to 75° and a step size of 0.02°. A fixed divergence slit of 0.6 mm, receiving slit of 0.2 mm, and scatter slit of 8 mm were used. No incident-beam mask was applied. Samples were manually ground to <75 μm and packed into standard sample holders. The scans covered a 2θ range from 5° to 75°, with a counting rate of 2 per minute. Mineral identification and subsequent data processing were conducted using Jade 6.0 software.
Thin sections from all Mn ore samples underwent analysis through optical microscopy and field-emission scanning electron microscopy (FE-SEM) at the same laboratory. Before FE-SEM imaging, the thin sections were coated with a nanometer-thick layer of platinum-gold (Au). Observations were performed with a Zeiss Sigma 300 FE-SEM (Carl Zeiss AG, Oberkochen, Germany) under the following conditions: an 8 mm working distance, 20 kV accelerating voltage, and a beam current of 10 nA.
All 40 Mn ore samples were ground to a 200-mesh size for major and trace element analyses. Major elements were quantified using a Rigaku 3080E X-ray fluorescence spectrometer (XRF) (Rigaku, Tokyo, Japan) at the Central Laboratory of the South-Central Bureau of the China Metallurgical Geology Bureau, with analytical uncertainties below 3%. Prior to XRF analysis, loss on ignition (LOI) was determined. For trace and rare earth element analysis, a PerkinElmer Elan 9000 ICP-MS (PerkinElmer, Shanghai, China) was employed, with sample preparation involving the dissolution of approximately 40 mg of powdered material in an HF + HNO3 mixture in a high-pressure Teflon bomb. Rhodium (Rh) was used as an internal standard to monitor signal drift, and the analytical precision was within ±5%. Data were normalized to post-Archean Australian shale (PAAS) values to assess REE distribution patterns and calculate Ce and Eu anomalies [31].
Carbon and oxygen isotope ratios were measured on ten bulk Mn ore samples using a Finnigan MAT-253 isotope ratio mass spectrometer (IRMS) (Thermo Fisher Scientific, Waltham, United States) with an automated carbonate preparation system (Kiel IV) at Southwest University, Chongqing. Mn carbonate minerals in Mn oxide ores were extracted using a microdrill. The Mn carbonates were reacted with 100% H3PO4 for 220 s at 70 °C. Analyses included random replicate samples, with standards measured every nine samples. Isotopic ratios are expressed in per mil relative to the Vienna Peedee Belemnite (V-PDB) standard. The internal precision (1σ) for both δ13C and δ18O was better than ±0.1‰, with an external precision within ±0.5‰.

4. Result

4.1. Mineralogy

In hand specimens, the Mn ores predominantly exhibit a laminated structure (Figure 5C). Notably, some of the laminated ores contain abundant ooids, ranging in diameter from 3 to 5 mm (Figure 5D). X-ray diffraction (XRD) analysis indicates that the ores are primarily composed of kutnohorite, with quartz, calcite, dolomite, muscovite, and clinochlore as the main gangue minerals (Figure 6).
Backscatter electron (BSE) imaging reveals that kutnohorite predominantly forms irregularly shaped particles, with a minor presence of euhedral kutnohorite (Figure 7A–C). The part of kutnohorite particles typically surround euhedral dolomite cores (Figure 7A,B). Clinochlore and quartz are commonly observed interspersed among the kutnohorite particles (Figure 7A,B). Small amounts of metal sulfides, including sphalerite and pyrite, are occasionally present within the manganese ores (Figure 7A,B). The ooids are primarily composed of kutnohorite, muscovite, and quartz (Figure 7D–F). The kutnohorite in the ooids primarily forms euhedral particles, lacking dolomite cores, with muscovite and quartz distributed among the kutnohorite particles.

4.2. Geochemistry

The major element compositions of the Mn samples are summarized in Table 1. The Mn content varies across the three cores. In the Mn ores of ZK5101, MnO concentrations range from 7.9 wt% to 15.3 wt%, with an average of 11.7 wt%. In contrast, ZK0301 exhibits higher MnO contents, ranging from 13.9 wt% to 17.8 wt%, with a mean value of 15.6 wt%. The highest MnO concentrations are observed in ZK1205, ranging from 14.2 wt% to 22.9 wt%, with an average of 17.2 wt%. All three cores show elevated total iron oxide (TFe2O3) content, varying from 2.4 wt% to 10.1 wt%, with a mean of 5.1 wt%. Additionally, the P2O5 contents are relatively low across all three cores. Other major oxides present in the Mn ores include SiO2 (18.7–34.6 wt%, average 27.0 wt%), Al2O3 (4.3–8.3 wt%, average 6.13 wt%), CaO (10.1–19.7 wt%, average 14.9 wt%), and MgO (2.9–5.9 wt%, average 4.1 wt%).
The trace element compositions of the samples are summarized in Table 2. Concentrations of trace elements such as Co, Ni, Zn, Pb, and Sr in the Mn ore samples exceed PAAS values, while other trace elements are present at lower concentrations compared to PAAS. All Mn ore samples exhibit notably high strontium (Sr) concentrations, with an average value of 804 ppm, which is in alignment with the presence of calcite and dolomite, as confirmed through backscatter electron (BSE) imaging and X-ray diffraction (XRD) analysis. Regarding redox-sensitive elements, the concentrations of uranium (U), vanadium (V), and molybdenum (Mo) in the drill core samples range from 1.15 to 2.74 ppm, 29.89 to 181.63 ppm, and 0.24 to 3.16 ppm, respectively. The U/Al, V/Al, and Mo/Al ratios vary between 0.4 ppm/% and 1.0 ppm/% (average 0.6 ppm/%), 12.12 ppm/% and 70.02 ppm/% (average 25.0 ppm/%), and 0.02 ppm/% and 0.39 ppm/% (average 0.1 ppm/%), respectively.
The rare earth element + Yttrium (REY) compositions of the three core samples are presented in Table 3. The PAAS-normalized rare earth element patterns for the Mn ores are illustrated in Figure 8A. The PAAS-normalized rare earth element and yttrium (REY) patterns for the manganese ore samples show an obvious depletion in the light REY (Laₛₙ/Ybₛₙ = 0.5–0.8), accompanied by minor positive cerium (Ce) anomalies, ranging from 1.0 to 1.3 (average 1.1), and positive europium (Eu) anomalies, varying between 0.8 and 1.3 (average 1.1). The total REY content is low, ranging from 82.0 to 169.2 ppm, with an average of 122.3 ppm. The (Y/Ho)SN and (La/Ce)SN ratios (where SN refers to PAAS-normalized values) across all Mn ore samples range from 0.9 to 1.2 (mean = 1.0) and 0.8 to 1.2 (mean = 0.9), respectively. A positive correlation is observed between the Ce anomalies and MnO concentrations (R2 = 0.3), while no significant correlation is found between the Ce anomalies and the concentrations of Al2O3, TFe2O3, or P2O5 in the manganese ores. In comparison, host rock samples (silicious limestone and mudstone) generally exhibit slightly higher total REY concentrations and lack Ce and Eu anomalies [20,21]. The PAAS-normalized rare earth element and yttrium (REY) patterns for the host rock samples predominantly exhibit negative Ce anomalies, with an absence of europium Eu anomalies (Figure 8B) [20,21]. However, a small number of host rock samples display positive Ce anomalies (Figure 8B) [20,21].
The carbon (C) and oxygen (O) isotopic compositions of the manganese ore samples are provided in Table 4. The manganese carbonate ores show δ13C-VPDB values ranging from −2.3‰ to −6.1‰, with an average of −4.7‰. The δ18O-VPDB values for these ores vary from −7.8‰ to −8.9‰. For the host rocks (silicious limestone and mudstone), the δ13C-VPDB values range from −0.36‰ to 2.47‰, with an average of 0.6‰ [10] (Table 4). Notably, a negative correlation is observed between the MnO content and δ13C-VPDB values (R2 = 0.65).

5. Discussion

5.1. Redox Conditions During Manganese Deposition

The geochemical behavior of Mn in the surface environment is primarily governed by the Eh-pH conditions [32]. Under oxic conditions, dissolved Mn2+ is oxidized to form Mn oxides. Conversely, solid Mn oxides are reduced to dissolved Mn2+ through reactions with reductants such as organic matter, CH4, H2S, and Fe2+ [2,6,33,34]. Earlier studies proposed a diagenetic model in which Mn is predominantly present as Mn oxides in oxic water column, which are subsequently reduced to form Mn carbonates during the diagenetic process [2,4,5,6,35]. More recently, it has been reported that Mn carbonates can directly precipitate in anoxic water columns in certain modern lakes [11,12]. While the mineralization efficiency of this direct precipitation pathway for Mn carbonates remains to be further validated, some studies have employed this model to explain the formation of sedimentary Mn deposits [9,10,15,16,17,18]. Therefore, understanding the redox environment during Mn deposition is crucial for elucidating the precipitation pathway of Mn carbonates.
Redox-sensitive elements, such as vanadium (V), uranium (U), and molybdenum (Mo), are widely used for reconstructing the redox conditions of depositional environments [36,37,38]. Previous research calibrated the geochemical behavior of V, U, Mo, and rhenium (Re) in modern sedimentary environments with known redox conditions [38]. They proposed that the enrichment of both Mo (>5 ppm/%) and V (23 ppm/% < V < 46 ppm/%) indicates a strictly euxinic basin-type depositional environment. Enrichments of V (>46 ppm/%), U (>5 ppm/%), and Mo (>5 ppm/%) suggest the presence of an anoxic core within a perennial oxygen minimum zone (OMZ), whereas the enrichment of U (>1 ppm/%) coupled with low enrichment of V (<23 ppm/%) and Mo (<5 ppm/%) is indicative of oxic waters beneath the cores of a perennial OMZ. In contrast, normal oxic waters exhibit low enrichments of U (<1 ppm/%), V (<23 ppm/%), and Mo (<0.4 ppm/%). In our study, most Mn ore samples show low enrichment of U (0.38–1.0 ppm/%), V (11.0–70.0 ppm/%), and Mo (0.02–0.26 ppm/%), plotting within the oxic field in U/Al vs. V/Al and Mo/Al vs. V/Al diagrams, indicating a normal oxic condition (Figure 9). Furthermore, host rock samples also display low enrichments of U (0.4–3.7 ppm/%), V (13.1–23.2 ppm/%), and Mo (0.1–0.6 ppm/%), which is consistent with the Mn ore samples, indicating a normal oxic condition [19,22,23,24,39]. Collectively, these findings suggest that Mn deposition occurred under an oxic water environment.
The redox-sensitive rare earth element cerium (Ce) is commonly employed to reconstruct redox conditions [40,41]. In oxic marine environments, dissolved Ce3+ is oxidized to insoluble CeO2 and rapidly scavenged by Fe-Mn oxides and organic matter. Consequently, modern oxic waters typically exhibit strong negative Ce anomalies, while marine sediments containing Fe-Mn oxides or organic matter often display positive Ce anomalies [42,43,44,45,46]. The lack of correlation between Al2O3 and Ce anomalies in the Dongping Mn deposit suggests that these geochemical proxies are not influenced by clay minerals, thereby making them reliable indicators for investigating the redox condition (Figure 10A). Furthermore, the absence of a correlation between Ce anomalies and TFe2O3 or P2O5 indicates that Ce anomalies are unaffected by Fe oxides and organic matter in the Dongping Mn deposit (Figure 10C,D). The manganese ore samples from the Dongping manganese deposit exhibit slightly positive Ce anomalies (0.9–1.4; avg. 1.2), suggesting that Mn deposition occurred in an oxic water column. Additionally, these positive Ce anomalies show a weak positive correlation with MnO concentrations in the Mn carbonate ore samples, implying that the positive Ce anomalies resulted from oxidative scavenging of Ce by Mn oxides (Figure 10B). In contrast to modern Mn nodules and crusts, which display pronounced positive Ce anomalies, the Mn ore samples show only slight positive Ce anomalies. This may be due to the remobilization of Ce3+ into bottom oxic waters during the reduction in Mn oxides in anoxic pore waters [47].
The δ13C compositions of Mn carbonates provide essential insights into the origin of dissolved inorganic carbon (DIC) [2,8]. The lack of correlation between carbon and oxygen isotopes indicates that the carbon isotopic composition of Mn carbonate ores is minor influenced by diagenesis (Figure 11). The carbon isotopic values of Mn ore samples range from −2.3‰ to −6.1‰, with an average of −4.7‰, which are notably lower than those of the host rocks and contemporaneous seawater (avg. 3.3‰) [10]. The negative carbon isotopic values in the Mn ores suggest that the partitioning of DIC is derived from the oxidation of organic carbon. The negative δ13C values in the Dongping Mn deposit are similar to those of the “Adilabad” and “Wafangzi” Mn deposits [48,49,50] and are slightly higher than those of other sedimentary Mn deposits, which typically exhibit values lower than −8‰ (e.g., Ortokarnash, Urkut, and Datangpo Mn deposits) [51,52]. The slightly higher carbon isotopic composition observed in the Dongping Mn deposit may result from the abundant calcite and dolomite in the Mn ores. These carbonate minerals likely contribute to a higher carbon isotopic signal. Moreover, a clear negative correlation is observed between MnO concentration and carbon isotopic values in the Mn carbonate ores (Figure 11). These findings provide strong evidence that Mn carbonates are formed through redox reactions between Mn oxides and organic matter. Overall, our results support the hypothesis that Mn carbonate ores are formed through the reduction in Mn oxides during the early diagenetic process.

5.2. Source of Mn in Dongping Mn Deposit

The concentration of Al2O3 in marine sediments serves as an indicator of terrigenous clastic material input [53,54]. However, the Mn carbonate ore samples from the Dongping Mn deposit exhibit low Al2O3 concentrations, coupled with a negative correlation with MnO content, suggesting that the Mn is unlikely to have originated from terrigenous sources. The formation of sedimentary Mn deposits is commonly associated with hydrothermal activities [5,7,13,55]. A variety of geochemical proxies and discrimination diagrams have been employed to elucidate the origins of sedimentary Mn deposits [56,57]. Hydrothermal Fe-Mn oxides typically exhibit Al/(Al+Mn+Fe) ratios of less than 0.3 [53,58]. In the case of the Dongping Mn deposit, the Al/(Al+Mn+Fe) ratios range from 0.1 to 0.29, with a mean of 0.15. Co/Zn ratios in hydrothermal Mn deposits generally hover around 0.15, while hydrogenous manganese deposits typically exhibit ratios exceeding 2.5 [58]. For the Dongping Mn ores, Co/Zn ratios range from 0.35 to 1.98, with an average of 0.74, which aligns with characteristics typical of hydrothermal Mn deposits. The Mn‒Fe‒(Co+Ni+Cu) × 10 ternary diagram and the Co/Zn vs. Co+Ni+Cu diagrams remain fundamental tools for distinguishing the origins of Fe-Mn sediments [55,58,59]. Although originally developed for modern marine Fe-Mn crusts, these discrimination diagrams have been widely applied to ancient Mn carbonate deposits where precursor oxides formed under similar depositional environments [9,10,16,18]. Our analysis reveals that all Mn ore samples plot within the hydrothermal field on both diagrams, strongly suggesting a dominant hydrothermal activity for the Dongping Mn deposit (Figure 12).
Recent studies have highlighted the utility of REY patterns as reliable proxies for determining the origin of Fe-Mn oxides [43,60]. The ionic radii and chemical properties of yttrium (Y) are similar to those of holmium (Ho), suggesting that these elements share analogous geochemical behaviors [43]. Different rock and fluid types exhibit distinct Y/Ho ratios; for instance, seawater typically shows Y/Ho ratios ranging from 44 to 74, while shales, chondrites, and most volcanic rocks generally have ratios between 26 and 28 [42,61,62]. In the Dongping Mn ores, Y/Ho ratios range from 24.98 to 32.3, with an average of 28.03, which is consistent with characteristics indicative of volcanic activity or hydrothermal sedimentation processes. While the Y/Ho ratio is traditionally used as a redox indicator, previous studies have also applied it, in combination with REE patterns and Ce anomalies, as a supplementary proxy for distinguishing hydrothermal input [42]. Moreover, hydrothermal Fe-Mn oxides commonly exhibit negative Ce anomalies, depleted light rare earth elements (LREE), and low total REE contents, which are attributed to rapid sedimentation rates. In contrast, hydrogenous Fe-Mn sediments display more pronounced Ce anomalies, enriched middle REE (MREE), and higher total REE contents, due to much slower growth rates of less than ten millimeters per million years [43,63]. It is crucial to note that these geochemical proxies can be modified through prolonged exposure to seawater [43,64,65]. Even after equilibrium is achieved for non-redox-sensitive REY, the (Ce/Ce*)SN ratio continues to increase as long as the oxide surface remains exposed to seawater. Moreover, since the Mn carbonates in Dongping Mn deposit are interpreted to result from early diagenetic reduction in Mn oxides, it is likely that they preserved the REE signatures of their precursor phases. In the case of the Dongping Mn ores, the samples exhibit slightly positive Ce anomalies, low total REE content, and depleted LREE, all of which point to a hydrothermal origin. The slight positive Ce anomalies may result from the prolonged exposure of Mn oxides to seawater. Taken together, these findings strongly support the hypothesis that the Mn ores in the Dongping deposit have a hydrothermal origin.
Based on above discussion, we suggest that metallogenic mechanism of Dongping Mn deposit was controlled by sedimentary-diagenetic process. During the Early Triassic, the Shipao Formation’s slope-basin facies provided a high-energy, oxic depositional setting in which hydrothermally derived Mn2+, channeled along faults and folds, precipitated rapidly as Mn oxides in laminated and oolitic textures. Subsequently, early diagenetic processes, which are mediated by microbes, reduced these Mn oxides to form kutnohorite-rich carbonates, a transformation recorded by negative δ13C values (−2.3‰~−6.1‰). Collectively, these lines of evidence demonstrate that Dongping’s economic Mn carbonate ores originated through a two-stage process of hydrothermal supply and diagenetic conversion, providing a robust genetic model for exploration of analogous deposits in hydrothermally influenced, oxic slope-basin environments.

6. Conclusions

The Dongping Mn deposit formed through a two-stage process. Initially, hydrothermal fluids introduced dissolved Mn2+ into an oxic slope-basin setting, where it precipitated as Mn oxides precursor. These Mn oxides were then reduced by organic-matter oxidation during early diagenesis, forming the kutnohorite-rich carbonate ores observed today. Geochemical proxies and carbon isotope composition collectively substantiate the diagenetic transformation of Mn oxides and a dominant hydrothermal source. This integrated model not only reconciles previous divergent interpretations but also provides a predictive framework for exploration of similar sedimentary Mn carbonate deposits in hydrothermally influenced, oxic slope-basin environments.

Author Contributions

Conceptualization, R.-Z.L., Y.Z. and Q.H.; Methodology, L.-N.Z.; Investigation, R.-Z.L., S.J., P.L., T.L. and D.-Q.D.; Data curation, P.L.; Writing—original draft, R.-Z.L.; Writing—review & editing, Y.Z. and Q.H.; Visualization, T.L., D.-Q.D., Y.Z., L.-N.Z. and Q.H.; Supervision, Q.H.; Project administration, R.-Z.L. and P.L.; Funding acquisition, S.J. All authors have read and agreed to the published version of the manuscript.

Funding

This work was financially supported by the Key Research and Development Program of China (No. 2022YFC2903404) and Geological Comprehensive Research Project of China Metallurgical Geological Bureau (No. [2025]CMGBDZYJ001).

Data Availability Statement

All the data are available in the manuscript as Table 1, Table 2, Table 3 and Table 4 are also available from the corresponding author upon reasonable request.

Acknowledgments

We sincerely thank the Tiandeng Manganese Mine Branch of South Manganese Industry Group Co., Ltd. for their strong support during the field investigation. We also gratefully acknowledge the reviewers for their valuable suggestions that helped improve this manuscript.

Conflicts of 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.

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Figure 1. Simplified local geological map of the Triassic Mn metallogenic belt.
Figure 1. Simplified local geological map of the Triassic Mn metallogenic belt.
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Figure 2. Comprehensive stratigraphic successions of the Dongping Member in the Dongping Mn mining area. T2bf: Middle Triassic Baifeng Formation; T1s: Lower Triassic Shipao Formation.
Figure 2. Comprehensive stratigraphic successions of the Dongping Member in the Dongping Mn mining area. T2bf: Middle Triassic Baifeng Formation; T1s: Lower Triassic Shipao Formation.
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Figure 3. Simplified geological map of the Dongping manganese ore deposit, showing the distribution of key geological features and the location of the ore bodies.
Figure 3. Simplified geological map of the Dongping manganese ore deposit, showing the distribution of key geological features and the location of the ore bodies.
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Figure 4. The characteristic Dongping Member in the Dongping Mn deposit.
Figure 4. The characteristic Dongping Member in the Dongping Mn deposit.
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Figure 5. (A). Field photograph illustrating the banded manganese ore bodies in the Dongping Member. (B). Core characteristics of the manganese ores from the Dongping manganese deposit. (C). Hand-specimen image of the laminated manganese carbonate ore, displaying a high abundance of ooids. (D). Hand-specimen image of the laminated manganese carbonate ore.
Figure 5. (A). Field photograph illustrating the banded manganese ore bodies in the Dongping Member. (B). Core characteristics of the manganese ores from the Dongping manganese deposit. (C). Hand-specimen image of the laminated manganese carbonate ore, displaying a high abundance of ooids. (D). Hand-specimen image of the laminated manganese carbonate ore.
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Figure 6. (A,B). X-ray diffraction (XRD) patterns of selected manganese ore samples, with kutnohorite identified as the primary Mn-bearing mineral.
Figure 6. (A,B). X-ray diffraction (XRD) patterns of selected manganese ore samples, with kutnohorite identified as the primary Mn-bearing mineral.
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Figure 7. Photomicrographs depicting the complex textural characteristics of manganese carbonate ores. (A–C). Kutnohorite predominantly forms irregularly shaped particles, with a minor presence of euhedral kutnohorite. Some particles are typically enveloping euhedral dolomite cores, and clinochlore and quartz are commonly interspersed among the kutnohorite particles. (D–F). Ooids primarily consist of cubic kutnohorite, devoid of dolomite cores, with muscovite and quartz distributed among the kutnohorite particles.
Figure 7. Photomicrographs depicting the complex textural characteristics of manganese carbonate ores. (A–C). Kutnohorite predominantly forms irregularly shaped particles, with a minor presence of euhedral kutnohorite. Some particles are typically enveloping euhedral dolomite cores, and clinochlore and quartz are commonly interspersed among the kutnohorite particles. (D–F). Ooids primarily consist of cubic kutnohorite, devoid of dolomite cores, with muscovite and quartz distributed among the kutnohorite particles.
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Figure 8. (A). PAAS-normalized rare earth element + yttrium (REY) patterns in the Dongping Mn ore samples. (B). PAAS-normalized rare earth element + yttrium (REY) patterns in the host rock (modified from [20,21]).
Figure 8. (A). PAAS-normalized rare earth element + yttrium (REY) patterns in the Dongping Mn ore samples. (B). PAAS-normalized rare earth element + yttrium (REY) patterns in the host rock (modified from [20,21]).
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Figure 9. Cross-plots of V/Al concentrations versus U/Al (A) and Mo/Al (B) for manganese ores and host rocks. Diagrams modified from [33]; geochemical data for host rocks are incorporated from [20].
Figure 9. Cross-plots of V/Al concentrations versus U/Al (A) and Mo/Al (B) for manganese ores and host rocks. Diagrams modified from [33]; geochemical data for host rocks are incorporated from [20].
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Figure 10. Cross-plots of Ce/Ce* ratios versus Al2O3 (A), MnO (B), P (C), and Fe (D) concentrations.
Figure 10. Cross-plots of Ce/Ce* ratios versus Al2O3 (A), MnO (B), P (C), and Fe (D) concentrations.
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Figure 11. Cross-plots of carbon isotopic ratios versus oxygen isotopic ratios (A) and MnO concentrations (B) in the Mn ore samples.
Figure 11. Cross-plots of carbon isotopic ratios versus oxygen isotopic ratios (A) and MnO concentrations (B) in the Mn ore samples.
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Figure 12. (A). Binary plot of Co/Zn ratios versus Co+Cu+Ni concentration in Mn ores. (B). Mn-Fe-(Co+Ni+Cu) × 10 ternary diagram.
Figure 12. (A). Binary plot of Co/Zn ratios versus Co+Cu+Ni concentration in Mn ores. (B). Mn-Fe-(Co+Ni+Cu) × 10 ternary diagram.
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Table 1. Major elemental composition of Mn carbonate ores.
Table 1. Major elemental composition of Mn carbonate ores.
NoSampleLocationSiO2CaOMgOAl2O3Fe2O3(t)MnOP2O5TiO2LOIAl/(Al+Fe+Mn)
1ZK5101-H1Hanliu26.5616.714.215.373.5014.640.070.0126.020.14
2ZK5101-H2Hanliu21.1019.703.844.613.2115.310.060.0328.370.12
3ZK5101-H3Hanliu34.6814.243.298.143.7910.660.130.0321.130.24
4ZK5101-H4Hanliu26.8217.323.454.9010.0711.930.180.0423.600.12
5ZK5101-H5Hanliu30.7814.374.016.358.6410.960.210.0321.100.17
6ZK5101-H6Hanliu28.0416.023.615.807.9311.610.100.0122.980.15
7ZK5101-H7Hanliu30.6414.023.827.157.0711.320.200.1121.660.19
8ZK5101-H8Hanliu33.5016.592.948.323.837.910.110.0221.400.29
9ZK5101-H9Hanliu30.0015.523.307.593.0711.150.120.0223.840.23
10ZK5101-H10Hanliu26.5616.243.666.214.7111.210.110.1825.600.18
11ZK5101-H11Hanliu26.1215.993.705.767.1410.790.150.0225.060.16
12ZK5101-H12Hanliu18.8619.993.434.815.1112.280.070.2428.530.14
13ZK5101-H13Hanliu29.7015.694.165.854.1412.690.110.0123.230.17
14ZK5101-H14Hanliu31.2315.184.406.654.1111.420.090.0322.630.20
15ZK0301-H1Dinuo30.3412.093.706.865.0715.470.110.0122.180.16
16ZK0301-H2Dinuo26.4113.194.085.676.5016.610.110.0124.100.12
17ZK0301-H3Dinuo27.5510.065.856.738.3617.660.370.0121.370.13
18ZK0301-H4Dinuo28.2512.674.437.334.4315.740.160.0322.800.17
19ZK0301-H5Dinuo31.0213.693.737.274.1413.530.120.0121.580.19
20ZK0301-H6Dinuo25.9513.703.655.515.8917.800.100.0224.000.12
21ZK0301-H7Dinuo28.9616.343.626.404.4314.900.130.0223.840.16
22ZK0301-H8Dinuo25.8417.183.555.613.2114.070.090.0226.100.15
23ZK0301-H9Dinuo29.5613.624.726.903.8913.940.100.0423.590.18
24ZK0301-H10Dinuo18.8619.734.514.355.1417.050.120.0228.570.10
25ZK0301-H11Dinuo27.4215.094.546.533.3613.950.100.0224.250.17
26ZK0301-H12Dinuo21.6617.254.125.232.9316.360.090.0128.150.13
27ZK1205-H1Dinuo29.1010.285.807.128.6416.360.340.0120.740.14
28ZK1205-H2Dinuo19.2416.743.344.889.3616.410.120.0126.740.10
29ZK1205-H3Dinuo29.1811.024.636.404.0318.430.050.0122.230.14
30ZK1205-H4Dinuo28.7813.844.617.093.6415.140.050.0523.150.18
31ZK1205-H5Dinuo29.9512.734.866.784.1714.920.120.0121.900.17
32ZK1205-H6Dinuo23.7218.324.315.403.2114.510.150.0125.810.15
33ZK1205-H7Dinuo28.9010.904.846.434.2117.400.110.0323.380.14
34ZK1205-H8Dinuo26.5415.544.035.542.7914.460.070.0326.450.15
35ZK1205-H9Dinuo30.3012.134.966.703.9316.190.100.0121.860.16
36ZK1205-H10Dinuo29.9214.565.046.933.4314.240.100.0222.510.18
37ZK1205-H11Dinuo18.7413.763.624.377.9322.980.110.0127.310.08
38ZK1205-H12Dinuo23.5215.773.415.494.1419.440.030.0126.730.12
39ZK1205-H13Dinuo24.0214.963.184.662.4319.870.080.0225.720.10
40ZK1205-H14Dinuo21.6611.875.015.377.5020.990.090.0124.770.10
Table 2. Trace elemental composition of Mn carbonate ores.
Table 2. Trace elemental composition of Mn carbonate ores.
NoSampleLocationBBaCoCuCrMoNiPbSrThUVZnZrAl2O3AlV/AlU/AlMo/AlMo/UCo/ZnCo+Cu+Ni
1ZK5101-H1Hanliu23.89327.3374.8037.8132.090.7468.3388.02683.295.951.72115.56112.70155.005.372.8440.650.610.090.150.66180.95
2ZK5101-H2Hanliu27.79239.10145.9427.2829.370.5377.5615.80905.104.951.4356.9073.57164.004.612.4423.310.590.090.151.98250.78
3ZK5101-H3Hanliu31.78452.7847.8756.3441.691.2685.7828.80748.5813.722.7486.01138.20209.008.144.3119.960.640.070.110.35189.99
4ZK5101-H4Hanliu11.1977.84124.4937.5353.030.6371.3268.061082.927.382.63181.6397.01235.004.902.5970.021.010.090.091.28233.35
5ZK5101-H5Hanliu21.21215.4184.8947.7238.080.4782.8829.34705.408.322.1292.97139.62169.006.353.3627.650.630.040.070.61215.50
6ZK5101-H6Hanliu12.01116.0688.6919.2432.850.8469.0712.58666.295.811.4857.10112.57132.005.803.0718.600.480.090.180.79176.99
7ZK5101-H7Hanliu31.60374.0352.7344.6541.190.4172.2519.48808.707.121.4992.14130.83205.007.153.7924.340.390.030.070.40169.63
8ZK5101-H8Hanliu11.03100.0578.8728.2723.710.4241.6539.241194.294.461.6673.7784.96215.508.324.4016.750.380.020.060.93148.79
9ZK5101-H9Hanliu24.19266.8645.3842.6035.962.4365.0520.43792.026.821.6667.24112.12186.007.594.0216.730.410.150.360.40153.03
10ZK5101-H10Hanliu20.76205.0328.6825.9723.011.5038.2017.621149.795.021.4036.3067.60248.006.213.2911.040.430.140.330.4292.85
11ZK5101-H11Hanliu37.16413.5247.3431.6338.490.4072.1730.06896.447.721.7972.75122.63196.005.763.0523.860.590.040.070.39151.14
12ZK5101-H12Hanliu33.21358.2738.1633.0621.210.5047.8231.591359.557.042.4159.5286.49275.004.812.5523.370.950.080.080.44119.04
13ZK5101-H13Hanliu30.68367.7696.0035.4635.400.3089.5618.69667.907.091.3756.05123.90173.005.853.1018.100.440.030.070.77221.02
14ZK5101-H14Hanliu38.46495.6754.9940.8037.931.3884.9334.67719.748.792.1289.65114.26176.006.653.5225.470.600.110.180.48180.72
15ZK0301-H1Dinuo10.25251.70122.0826.8435.372.4299.9726.67742.255.501.6072.53109.53169.006.863.6319.970.440.180.421.11248.89
16ZK0301-H2Dinuo23.97510.59113.4553.6639.480.6593.6129.15683.038.021.6979.16131.73187.005.673.0026.370.560.070.130.86260.72
17ZK0301-H3Dinuo25.48608.59100.4148.4240.310.3498.5827.45612.257.471.86119.93123.06159.006.733.5633.660.520.030.050.82247.42
18ZK0301-H4Dinuo17.08354.6888.0724.0134.670.4391.8233.86756.215.901.5471.43121.07156.007.333.8818.410.400.030.070.73203.90
19ZK0301-H5Dinuo16.47474.0694.0748.1437.440.2493.2325.55708.796.312.27111.91124.66160.007.273.8529.080.590.020.030.75235.44
20ZK0301-H6Dinuo6.07248.65105.1125.8128.350.3381.8316.64758.315.921.1837.64101.03159.505.512.9212.900.400.040.101.04212.75
21ZK0301-H7Dinuo33.33331.3763.5325.7528.722.4275.9136.601047.645.541.3955.4992.11211.006.403.3916.380.410.210.510.69165.19
22ZK0301-H8Dinuo28.46272.0962.5926.7037.241.3292.9119.52726.167.081.3959.01114.87182.005.612.9719.870.470.150.320.54182.20
23ZK0301-H9Dinuo27.35426.7468.9147.3238.570.5491.4132.63843.347.041.8174.70113.95181.006.903.6520.450.500.040.080.60207.64
24ZK0301-H10Dinuo27.79345.7929.4819.6829.370.6046.7019.561049.275.602.1252.4477.55191.504.352.3022.770.920.110.120.3895.85
25ZK0301-H11Dinuo23.01375.7271.3133.6737.060.6282.3042.83634.917.431.8180.03113.00159.006.533.4623.150.520.050.100.63187.28
26ZK0301-H12Dinuo0.70468.30101.6439.3235.440.4690.8420.32838.346.211.5771.45130.25163.005.232.7725.810.570.060.110.78231.80
27ZK1205-H1Dinuo21.77550.7492.8670.7141.790.44107.3868.22727.417.902.01131.67149.11169.007.123.7734.930.530.030.060.62270.96
28ZK1205-H2Dinuo25.43430.4964.1130.1839.400.4692.1024.751089.536.982.1266.42115.53208.004.882.5825.710.820.070.080.55186.38
29ZK1205-H3Dinuo25.08495.6591.7857.4738.250.4090.6728.94491.736.602.16162.32131.34138.006.403.3947.910.640.030.050.70239.92
30ZK1205-H4Dinuo23.31640.3048.7429.7041.820.3695.3126.67801.087.961.82128.78126.38177.007.093.7534.310.490.030.050.39173.76
31ZK1205-H5Dinuo18.99675.45108.9211.2439.180.59107.5015.25605.896.981.5444.92115.33130.006.783.5912.520.430.050.110.94227.66
32ZK1205-H6Dinuo18.94370.5774.1710.3430.273.1664.5522.62969.145.871.9154.3993.60202.005.402.8619.020.670.390.580.79149.06
33ZK1205-H7Dinuo27.92380.6271.5127.0243.040.5995.8816.69820.178.061.8778.91126.57182.006.433.4023.180.550.050.090.57194.41
34ZK1205-H8Dinuo26.80336.4463.3430.4438.161.1695.9940.48722.816.471.92122.28126.46161.005.542.9341.690.650.140.210.50189.77
35ZK1205-H9Dinuo19.12432.3692.5253.3439.900.5188.9650.30547.347.202.08113.98121.73135.006.703.5532.130.590.040.070.76234.82
36ZK1205-H10Dinuo22.45573.4783.4480.3939.361.1990.4594.19771.597.512.22118.71132.79160.006.933.6732.360.600.090.150.63254.28
37ZK1205-H11Dinuo0.70602.90109.857.5132.390.5186.8214.13696.135.871.3336.14121.37141.004.372.3115.620.570.100.170.91204.17
38ZK1205-H12Dinuo16.28877.6963.7914.6636.570.3876.6215.57768.746.331.6054.2599.70156.005.492.9118.660.550.040.080.64155.07
39ZK1205-H13Dinuo14.97428.60122.557.5128.851.6184.7110.30782.635.171.1529.89101.99153.504.662.4712.120.470.260.571.20214.77
40ZK1205-H14Dinuo5.3681.49138.538.3930.100.6481.5011.14606.725.231.6053.8095.99120.505.372.8418.930.560.080.141.44228.41
Table 3. Rare earth elemental composition of Mn carbonate ores.
Table 3. Rare earth elemental composition of Mn carbonate ores.
NoSampleLocationLaCePrNdSmEuGdTbDyYHoErTmYbLuTREYY/HoCe*Eu*
1ZK5101-H1Hanliu20.3448.234.5416.733.400.793.720.573.5619.340.762.180.352.350.32127.1625.541.151.03
2ZK5101-H2Hanliu18.7342.744.1115.533.080.713.430.543.4020.820.712.120.322.040.30118.6129.131.121.01
3ZK5101-H3Hanliu28.9465.896.6524.635.001.035.260.875.2935.201.133.450.553.690.55188.1431.051.090.93
4ZK5101-H4Hanliu37.2878.397.9030.716.501.277.361.227.2347.781.544.380.654.190.61237.0131.021.050.84
5ZK5101-H5Hanliu31.0275.286.7725.355.281.105.770.935.7534.271.253.600.563.620.51201.0427.511.190.92
6ZK5101-H6Hanliu18.3447.034.1115.433.080.813.470.553.3121.950.712.040.332.180.32123.6630.771.251.14
7ZK5101-H7Hanliu23.8652.275.2019.453.851.064.020.634.0225.040.862.540.392.670.37146.2329.071.081.25
8ZK5101-H8Hanliu23.1547.634.7117.893.760.964.280.744.8033.431.033.190.463.170.44149.6432.301.051.10
9ZK5101-H9Hanliu20.1349.114.5116.943.370.803.540.573.5619.030.772.210.352.350.34127.6024.771.181.07
10ZK5101-H10Hanliu16.0632.633.5913.852.900.723.090.523.2218.090.722.060.332.090.28100.1325.230.991.11
11ZK5101-H11Hanliu23.6352.015.2719.703.950.954.070.653.9623.780.842.520.392.620.39144.7228.441.071.10
12ZK5101-H12Hanliu26.6748.315.8221.904.281.034.100.674.0923.700.832.550.392.630.38147.3528.500.891.15
13ZK5101-H13Hanliu20.4545.154.6817.303.420.813.540.593.6019.630.792.280.342.350.33125.2424.981.061.08
14ZK5101-H14Hanliu26.4656.455.8821.804.321.004.260.704.2024.770.892.720.412.740.42157.0227.811.041.08
15ZK0301-H1Dinuo32.3876.266.6725.105.151.266.130.986.0238.451.243.580.533.450.48207.6931.091.191.03
16ZK0301-H2Dinuo23.9758.465.3919.724.030.924.270.684.1825.690.872.670.422.730.43154.4329.631.181.03
17ZK0301-H3Dinuo24.3154.845.3619.754.060.954.250.704.2425.980.902.600.402.700.40151.4528.841.101.06
18ZK0301-H4Dinuo20.1949.234.4516.373.280.843.520.573.5021.300.742.190.332.210.32129.0128.871.191.14
19ZK0301-H5Dinuo27.6960.595.8921.644.481.085.010.805.0431.991.053.050.453.040.42172.2430.371.091.06
20ZK0301-H6Dinuo20.3553.804.3916.433.280.703.560.583.5520.630.762.280.362.400.34133.4327.021.310.95
21ZK0301-H7Dinuo19.8545.124.3616.623.450.933.650.593.6921.310.782.330.342.360.32125.6827.441.111.21
22ZK0301-H8Dinuo23.5047.475.1619.273.810.894.050.674.1423.530.862.650.402.720.41139.5227.360.991.06
23ZK0301-H9Dinuo23.6452.475.2519.573.970.983.980.664.0223.680.872.570.382.670.36145.0827.381.081.14
24ZK0301-H10Dinuo19.6145.874.4316.803.390.813.450.583.5519.660.752.260.332.290.33124.1326.111.131.10
25ZK0301-H11Dinuo25.8253.945.7421.124.130.944.570.724.2724.360.922.560.412.770.38152.6526.371.021.00
26ZK0301-H12Dinuo20.2747.654.5416.983.310.833.580.553.3919.390.702.060.332.180.32126.0727.891.141.11
27ZK1205-H1Dinuo23.7153.135.3019.643.830.984.060.684.1324.260.852.570.372.700.40146.6228.381.091.15
28ZK1205-H2Dinuo28.1556.016.3723.964.671.094.630.744.5426.380.942.740.422.780.41163.8428.000.961.09
29ZK1205-H3Dinuo25.8359.905.7122.204.611.105.090.845.0931.061.083.080.473.190.44169.7028.741.131.05
30ZK1205-H4Dinuo26.4657.655.9021.914.271.134.400.734.2924.110.912.670.392.850.39158.0426.571.061.21
31ZK1205-H5Dinuo23.9554.805.0918.903.741.013.890.623.6421.750.772.400.362.430.36143.7228.411.141.23
32ZK1205-H6Dinuo20.0046.034.3716.953.441.003.630.583.6020.390.792.360.362.330.31126.1325.911.131.31
33ZK1205-H7Dinuo23.6253.895.1919.323.790.783.990.643.9623.610.822.510.392.680.39145.5828.791.120.94
34ZK1205-H8Dinuo23.2352.625.3820.213.930.954.140.684.0023.650.872.510.372.630.36145.5227.211.081.10
35ZK1205-H9Dinuo26.2957.305.6021.034.401.074.770.794.5827.191.002.920.442.900.43160.7027.101.081.07
36ZK1205-H10Dinuo27.3054.986.1522.814.460.934.250.694.1924.190.872.620.402.720.38156.9427.930.980.99
37ZK1205-H11Dinuo19.0650.964.2615.963.340.913.500.573.4620.050.752.160.332.280.36127.9526.581.301.23
38ZK1205-H12Dinuo20.1452.224.4316.603.461.023.730.623.5221.320.752.270.352.370.34133.1328.371.271.31
39ZK1205-H13Dinuo17.9649.243.9915.113.030.823.300.553.2619.540.682.040.302.050.30122.1728.541.341.20
40ZK1205-H14Dinuo19.3253.984.2015.582.980.583.350.523.0517.640.671.960.302.080.31126.5426.311.380.84
Table 4. C and O isotopic composition of Mn carbonate ores.
Table 4. C and O isotopic composition of Mn carbonate ores.
NoSample Noδ13Cδ18O
1ZK5101-H2−4.28−7.83
2ZK5101-H3−3.66−8.93
3ZK5101-H6−3.70−8.65
4ZK5101-H12−2.30−8.63
5ZK0301-H1−5.66−8.62
6ZK0301-H3−5.72−8.21
7ZK0301-H12−3.39−8.33
8ZK1205-H2−6.02−7.88
9ZK1205-H13−5.94−8.32
10ZK1205-H9−6.14−8.41
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Li, R.-Z.; Jiang, S.; Long, P.; Long, T.; Ding, D.-Q.; Zhao, L.-N.; Zhang, Y.; Huang, Q. Metallogenic Mechanisms of the Lower Triassic Dongping Sedimentary Manganese Deposit in the South China Block: Mineralogical and Geochemical Evidence. Minerals 2025, 15, 847. https://doi.org/10.3390/min15080847

AMA Style

Li R-Z, Jiang S, Long P, Long T, Ding D-Q, Zhao L-N, Zhang Y, Huang Q. Metallogenic Mechanisms of the Lower Triassic Dongping Sedimentary Manganese Deposit in the South China Block: Mineralogical and Geochemical Evidence. Minerals. 2025; 15(8):847. https://doi.org/10.3390/min15080847

Chicago/Turabian Style

Li, Rong-Zhi, Sha Jiang, Peng Long, Tao Long, Da-Qing Ding, Ling-Nan Zhao, Yi Zhang, and Qin Huang. 2025. "Metallogenic Mechanisms of the Lower Triassic Dongping Sedimentary Manganese Deposit in the South China Block: Mineralogical and Geochemical Evidence" Minerals 15, no. 8: 847. https://doi.org/10.3390/min15080847

APA Style

Li, R.-Z., Jiang, S., Long, P., Long, T., Ding, D.-Q., Zhao, L.-N., Zhang, Y., & Huang, Q. (2025). Metallogenic Mechanisms of the Lower Triassic Dongping Sedimentary Manganese Deposit in the South China Block: Mineralogical and Geochemical Evidence. Minerals, 15(8), 847. https://doi.org/10.3390/min15080847

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