Stratabound Barite Deposits: Mineralogy, Isotope Geochemistry and Geochronology

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Mineral Deposits".

Deadline for manuscript submissions: 31 May 2025 | Viewed by 8069

Special Issue Editor


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Guest Editor
School of Applied Sciences, University of Brighton, Cockcroft Building, Lewes Road, Brighton BN2 4GJ, UK
Interests: mineralogy; geochemistry and formation of stratiform barite deposits; heavy minerals in sediments; alluvial gold microchemical characterization and provenance

Special Issue Information

Dear Colleagues,

Globally, a large proportion of mined barite is derived from strata-bound deposits hosted in carbonate, clastic, or volcanic rocks. Some of these deposits are ‘world-class’ in terms of their tonnage. A thorough understanding of how such deposits formed is of great importance in guiding exploration for further resources. Equally important from an academic perspective is the information that strata-bound barite can provide on past environments and diagenetic to hydrothermal processes, both in the Phanerozoic when marine sulfate was abundant and early in Earth’s history when marine sulfate was scarce. What is the mineralogical, isotopic, and/or geochronological evidence that these Archaean and Proterozoic barite deposits formed on the contemporaneous seafloor, and if so, what are the implications for the (local or global) marine environment at that time?

Carbonate-hosted strata-bound barite is often, though not everywhere, associated with epigenetic karst-fill or dissolution-replacement of Mississippi-valley-type (MVT) deposits and with diagenetic transitional to syngenetic Irish-type deposits. Stratabound barite mineralization hosted by Phanerozoic shales and other clastic sediments (clastic-dominant or ‘CD-type’ deposits) has been a topic of considerable discussion during the past thirty years. The ‘sedimentary exhalative’ (sedex) concept, which was popular in the twentieth century, invoking synsedimentary precipitation of barite in the water column or on the seabed, has been largely ousted by concepts involving subsurface diagenetic replacement processes. This Special Issue provides an opportunity for experts in the field to present mineralogical, isotopic, and geochronological evidence in support of their theories on ore formation in MV-, Irish- and CD-type strata bound barite (-Zn-Pb sulfide) deposits.

Dr. Norman Moles
Guest Editor

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Keywords

  • strata bound barite
  • sediment-hosted mineralization
  • volcanogenic deposit
  • sedex deposit
  • CD-type deposit
  • MVT deposit
  • bedded barite deposits
  • sediment-hosted barite deposits

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Published Papers (5 papers)

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Research

37 pages, 14137 KiB  
Article
Origin of Siderite and Baryte in a Carbonate-Replacement Ag-Pb-Zn-Cu Sulphide Deposit: Walton, Nova Scotia, Canada
by Chaneil J. Wallace, Daniel J. Kontak, Elizabeth C. Turner and Mostafa Fayek
Minerals 2025, 15(3), 327; https://doi.org/10.3390/min15030327 - 20 Mar 2025
Viewed by 536
Abstract
Siderite and baryte are common non-sulphide phases in sedimentary exhalative (SEDEX) deposits, but their formation remains poorly understood. Siderite is important as an exploration vector in some deposits, whereas baryte is important as a S source in some deposits. The past-producing Walton deposit [...] Read more.
Siderite and baryte are common non-sulphide phases in sedimentary exhalative (SEDEX) deposits, but their formation remains poorly understood. Siderite is important as an exploration vector in some deposits, whereas baryte is important as a S source in some deposits. The past-producing Walton deposit (Nova Scotia, Canada) consists of two ore types: (1) a sulphide body primarily hosted by sideritised Viséan Macumber Formation limestone (0.41 Mt; head grade of 350 g/t Ag, 4.28% Pb, 1.29% Zn, and 0.52% Cu), and (2) an overlying massive baryte body of predominantly microcrystalline baryte (4.5 Mt of >90% baryte). This study used optical microscopy, SEM-EDS, cathodoluminescence (CL), LA-ICP-MS, and SIMS sulphur isotope analysis of siderite and baryte to elucidate their origin and role in deposit formation. Siderite replaces limestone and contains ≤9 wt. % Mn, is LREE-depleted (PAAS-normalised REEY diagrams), and has low (<20) Y/Ho ratios. Sideritisation occurred due to dissimilatory iron reduction (DIR) that led to the breakdown of Fe-Mn-oxyhydroxides and organic matter, as indicated by light δ13CVPBD values and negative Y anomalies. The baryte body is dominated by a microcrystalline variety that locally develops a radial texture and coarsens to a tabular variety; it also occurs intergrown with, and as veins in, massive sulphides. Based on fluid inclusion data from previous studies, the coarser baryte types grew from a hot (>200 °C) saline (25 wt. % NaCl) fluid containing CO2-CH4 and liquid petroleum. Marine sulphate δ34SVCDT values typical of the Viséan (~15‰) characterise the baryte body and some tabular baryte types, whereas heavier (~20‰) and lighter (~10‰) values typify the remaining tabular types. The variations in tabular baryte relate to distinct zones identified by CL imaging and are attributed to the sulphate-driven anaerobic oxidation of methane (SDAOM) and oxidation of excess H2S after sulphide precipitation. These results highlight the importance of hydrocarbons (methane and organic matter) in the formation of both the siderite and the baryte at Walton and that DIR and the SDAOM can be important contributing processes in the formation of SEDEX deposits. Full article
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45 pages, 22848 KiB  
Article
Syn-Sedimentary Exhalative or Diagenetic Replacement? Multi-Proxy Evidence for Origin of Metamorphosed Stratiform Barite–Sulfide Deposits near Aberfeldy, Scottish Highlands
by Norman R. Moles, Adrian J. Boyce, Matthew R. Warke and Mark W. Claire
Minerals 2024, 14(9), 865; https://doi.org/10.3390/min14090865 - 25 Aug 2024
Cited by 1 | Viewed by 1562
Abstract
Bedded barite, Fe-Zn-Pb sulfides, carbonates, and cherts within Ediacaran (Dalradian Supergroup) graphitic metasediments near Aberfeldy in Scotland have previously been interpreted as chemical sediments precipitated from hydrothermal fluids episodically exhaled into marine basins filled with organic-rich mud, silt, and sand. Lithological variation and [...] Read more.
Bedded barite, Fe-Zn-Pb sulfides, carbonates, and cherts within Ediacaran (Dalradian Supergroup) graphitic metasediments near Aberfeldy in Scotland have previously been interpreted as chemical sediments precipitated from hydrothermal fluids episodically exhaled into marine basins filled with organic-rich mud, silt, and sand. Lithological variation and compositional diversity in pyrite and sphalerite reflect varied redox environments and proximity to hydrothermal discharges. Thick beds (>2 m) of barite have relatively uniform δ34S of +36 ± 1.5‰, considered to represent contemporaneous seawater sulfate, as negative Δ17O indicates incorporation of atmospheric oxygen during precipitation in the water column. However, certain features suggest that diagenetic processes involving microbial sulfate reduction modified the mineralogy and isotopic composition of the mineralization. Barite bed margins show decimeter-scale variation in δ34S (+32 to +41‰) and δ18O (+8 to +21‰), attributed to fluid-mediated transfer of dissolved barium and sulfate between originally porous barite and adjacent sediments, in which millimetric sulfate crystals grew across sedimentary lamination. Encapsulated micron-sized barium carbonates indicate early diagenetic barite dissolution with incorporation of sulfur into pyrite, elevating pyrite δ34S. Subsequently, sulfidation reactions produced volumetrically minor secondary barite with δ34S of +16 to +22‰. Overall, these processes affected small volumes of the mineralization, which originally formed on the seafloor as a classic SEDEX deposit. Full article
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25 pages, 6625 KiB  
Article
Fluid Inclusion, Rare Earth Element Geochemistry, and Isotopic (O and S) Characteristics of the Ardakan Barite Deposit, Yazd Province, Iran
by Ebrahim Ansari, Farhad Ehya, Ghodratollah Rostami Paydar and Sara Maleki Kheymehsari
Minerals 2024, 14(8), 739; https://doi.org/10.3390/min14080739 - 24 Jul 2024
Viewed by 1266
Abstract
The stratabound barite mineralization occurs in the Ardakan deposit as patches and veins in the dolomites and limestones of the Middle Triassic Shotori Formation. Rare-earth element (REE) geochemistry, O and S isotopes, and fluid inclusion data were used to identify the mode of [...] Read more.
The stratabound barite mineralization occurs in the Ardakan deposit as patches and veins in the dolomites and limestones of the Middle Triassic Shotori Formation. Rare-earth element (REE) geochemistry, O and S isotopes, and fluid inclusion data were used to identify the mode of barite formation. Barite is associated with subordinate fluorite and quartz and, to a lesser extent, with sphalerite, malachite, chrysocolla, and iron and manganese oxide-hydroxides. Barite contains a very low ∑REE concentration (14.80–19.59 ppm) and is enriched in light rare-earth elements (LREEs) relative to heavy rare-earth elements (HREEs). The low ∑REE content and the Ce/La ratio (4.0–6.5) indicate a hydrothermal (terrestrial) origin of the barite. Similar to barite, the ∑REE content in fluorite is low (0.14–6.52 ppm) and suggests a sedimentary setting. The Tb/Ca versus Tb/La diagram also indicates a hydrothermal origin of fluorite. The δ34S values in the barite (+27.9 to +32.4‰) indicate that the sulfur most likely originates from evaporites and/or connate waters from the Late Precambrian to the Lower Cambrian. The δ18O values (+15.9 to +18.1‰) in the barite show that the oxygen originated either from Late Precambrian–Lower Cambrian evaporites or from basinal brines with slightly higher δ18O values than the evaporites. The salinity and homogenization temperature ranges of the aqueous fluid inclusions in barite, fluorite, and quartz (0.88–16.89 wt% NaCl equivalent and 90–270 °C, respectively) reveal that the mineralizing fluids were formed from basinal brines with the participation of heated meteoric water. From this, it is concluded that the Ardakan barite deposit was formed by the meeting of heated, ascending sulfate-bearing meteoric water and cooler, Ba-bearing connate water trapped in the overlying Middle Triassic dolomites and limestones. The Ardakan deposit belongs to the structure-related class and the unconformity-related subclass of barite deposits. Full article
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37 pages, 50819 KiB  
Article
Barite Replacement as a Key Factor in the Genesis of Sediment-Hosted Zn-Pb±Ba and Barite-Sulfide Deposits: Ore Fluids and Isotope (S and Sr) Signatures from Sediment-Hosted Zn-Pb±Ba Deposits of Iran
by Abdorrahman Rajabi, Pouria Mahmoodi, Pura Alfonso, Carles Canet, Colin Andrew, Saeideh Azhdari, Somaye Rezaei, Zahra Alaminia, Somaye Tamarzadeh, Ali Yarmohammadi, Ghazaleh Khan Mohammadi and Rasoul Saeidi
Minerals 2024, 14(7), 671; https://doi.org/10.3390/min14070671 - 28 Jun 2024
Cited by 2 | Viewed by 1684
Abstract
Iran hosts more than 350 Precambrian to Cenozoic sediment-hosted Zn-Pb±Ba and barite-sulfide deposits, including shale-hosted massive sulfide (SHMS, also called SEDEX) and Irish-type and Mississippi Valley-type (MVT) mineralization, and barite is a common mineral in these deposits. In the SHMS deposits, barite is [...] Read more.
Iran hosts more than 350 Precambrian to Cenozoic sediment-hosted Zn-Pb±Ba and barite-sulfide deposits, including shale-hosted massive sulfide (SHMS, also called SEDEX) and Irish-type and Mississippi Valley-type (MVT) mineralization, and barite is a common mineral in these deposits. In the SHMS deposits, barite is typically found as fine-grained disseminations in thin laminae. In these deposits, the sulfide laminae often occur as diagenetic replacements and as bands containing authigenic and diagenetic barite and pyrite framboids. In the Irish-type Zn-Pb-Ba and stratabound barite-sulfide deposits, barite exhibits various textures, including fine-grained disseminated barite, banded zebra textures, veins, and massive barite lenses. In some of the giant Irish-type deposits, as well as in the stratabound barite-sulfide mineralization, the main stratabound sulfide ore is developed within a barite envelope and is characterized by the replacement of barite and pyrite by chalcopyrite, galena, and sphalerite. In the MVT deposits, the formation of barite is often related to dolomitization, and sulfide mineralization involves the replacement of the dolomitized carbonate rocks, as well as associated barite. Fluid inclusion studies on the Irish-type deposits indicate that the temperatures and salinities of the sulfide-forming fluids are higher compared to those of the barite-forming fluids. Fluid inclusion analyses of coarse-grained barites from Irish and MVT deposits reveal their hydrothermal origin. The δ3⁴S values of sulfide minerals (pyrite, sphalerite, and galena) in Irish-type deposits exhibit a broad range of low values (mostly −28 to +5‰), primarily revealing a process of bacterial sulfate reduction (BSR). However, the textures (replacement, colloform, and banded) and more positive sulfur isotope values (+1 to +36‰) in the SHMS Zn-Pb deposits suggest that bacterial sulfate reduction (BSR) plays a less significant role. We suggest that thermochemical sulfate reduction (TSR) connected to the direct replacement of barite plays a more relevant role in providing sulfur for the sulfide mineralization in the SHMS, barite-sulfide, and MVT deposits. Based on the textual evidence, sulfur isotopic data, and fluid inclusion studies, barite has been identified as a key controller for the subsequent Zn-Pb mineralization by providing a suitable host and significant sulfur contribution in the sediment-hosted Zn-Pb and stratabound barite-sulfide deposits. This implies that diagenetic barite might be a precursor to all types of sediment-hosted Zn-Pb mineralization. Full article
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30 pages, 40890 KiB  
Article
The Ballynoe Stratiform Barite Deposit, Silvermines, County Tipperary, Ireland
by Colin J. Andrew
Minerals 2024, 14(5), 498; https://doi.org/10.3390/min14050498 - 9 May 2024
Cited by 2 | Viewed by 1950
Abstract
The Ballynoe barite deposit is a conformable, mineralised horizon of Lower Carboniferous age overlying a diastem and mass faunal extinction demarking the transition from a quiet water environment to one of dynamic sedimentation. The geometry of the barite orebody correlates with the palaeotopography [...] Read more.
The Ballynoe barite deposit is a conformable, mineralised horizon of Lower Carboniferous age overlying a diastem and mass faunal extinction demarking the transition from a quiet water environment to one of dynamic sedimentation. The geometry of the barite orebody correlates with the palaeotopography of the footwall, which acted as an important control over the lateral extent, thickness, and nature of the mineralisation. Sedimentary features within the barite horizon suggest that it was precipitated in the form of a cryptocrystalline mud which underwent major diagenetic modification resulting in extensive stylolitisation, recrystallisation, and remobilisation. There is abundant and compelling geological and isotopic evidence for early local exhalation from the presence of a hydrothermal vent fauna consisting of delicately pyritised worm tubes and haematised filaments of apparent microbial origin. The worm tubes are remarkably similar to examples from modern and ancient volcanic-hosted massive sulphide deposits, and the filamentous microfossils have similarities to modern Fe-oxidising bacteria. Strontium in the barite has an 87Sr/86Sr ratio indistinguishable from seawater between 350 and 344 Ma whilst oxygen isotopes from barite and chert suggest a diagenetic origin in equilibrium with such seawater around 60–70 °C. Fluid inclusion studies have shown that, in general, low temperature inclusions are very saline (20%–25%) whilst at higher homogenisation temperatures they are more dilute (9%–12%). Full article
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