Apatite and Ore Deposits

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

Deadline for manuscript submissions: closed (15 July 2018) | Viewed by 13728

Special Issue Editor


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Guest Editor
Géosciences Rennes, UMR CNRS 6118, OSUR, Université de Rennes 1, 35042 Rennes CEDEX, France
Interests: metallogeny; geochemistry; geochronology; LA-ICP-MS; ore deposits

Special Issue Information

Dear Colleagues,

The study of ore deposits requires, among other things, the characterization of the fluid(s) responsible for mineralization, as well as understanding the timing and duration of ore deposition. This can be accomplished by the study of several types of objects (minerals, fluid inclusions, etc.) associated with mineralization. Apatite (Ca5(PO4)3(OH,F,Cl)) is an ubiquitous accessory phosphate mineral found in many types of rocks and environments. This is particularly true with regards to ore deposits. This mineral has several key characteristics that are very useful when one is interested in the characterization and/or the dating of the circulations of fluid(s) and/or the magmatism responsible for the deposition of mineralization. Apatite is an excellent trap for P, F, Cl, OH, as well as Rare Earth Elements, and can easily react in the presence of brines or aqueous fluids containing CO2, HCl, H2SO4 and/or F. In addition, this mineral often incorporates uranium during its crystallization. This makes it an excellent candidate for U-Pb dating. Moreover, this same mineral can also be dated using either the fission track and/or (U-Th)/He techniques. Therefore, it becomes possible to date the apatite crystallization age (or its interaction with late fluids), as well as the exhumation age of the host rocks and, subsequently, to have access to the whole history of the ore deposit, from its emplacement to its exhumation. In addition, oxygen isotopes studies can also be performed on this mineral to provide some valuable information on the fluid(s) temperature(s). Consequently, apatite constitutes, a priori, an excellent proxy to obtain, from a single mineral, multiple information on the fluids responsible for the setting up of mineralization (temperatures, compositions but also ages and durations). The main goal for this Special Issue is to collect different case studies, as well as innovative methodological contributions, indicating how the use of apatite associated with diverse types of ore deposits can provide some key information for the establishment of a metallogenic model.

Dr. Marc Poujol
Guest Editor

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Keywords

  • apatite
  • fluid
  • mineralization
  • ore deposits
  • geochemistry
  • geochronology
  • stable isotopes
  • fluid inclusions
  • thermochronology
  • economic geology

Published Papers (2 papers)

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Research

25 pages, 8458 KiB  
Article
Geology, Apatite Geochronology, and Geochemistry of the Ernest Henry Inter-lens: Implications for a Re-Examined Deposit Model
by Bradley W. Cave, Richard Lilly, Stijn Glorie and Jack Gillespie
Minerals 2018, 8(9), 405; https://doi.org/10.3390/min8090405 - 13 Sep 2018
Cited by 20 | Viewed by 7799
Abstract
The Ernest Henry Iron-Oxide-Copper-Gold deposit is the largest known Cu-Au deposit in the Eastern Succession of the Proterozoic Mount Isa Inlier, NW Queensland. Cu-Au mineralization is hosted in a K-feldspar altered breccia, bounded by two major pre-mineralization shear zones. Previous research suggests that [...] Read more.
The Ernest Henry Iron-Oxide-Copper-Gold deposit is the largest known Cu-Au deposit in the Eastern Succession of the Proterozoic Mount Isa Inlier, NW Queensland. Cu-Au mineralization is hosted in a K-feldspar altered breccia, bounded by two major pre-mineralization shear zones. Previous research suggests that Cu-Au mineralization and the ore-bearing breccia formed simultaneously through an eruption style explosive/implosive event, facilitated by the mixing of fluids at ~1530 Ma. However, the preservation of a highly deformed, weakly mineralized, pre-mineralization feature (termed the Inter-lens) within the orebody indicates that this model must be re-examined. The paragenesis of the Inter-lens is broadly consistent with previous studies on the deposit, and consists of albitization; an apatite-calcite-quartz-garnet assemblage; biotite-magnetite ± garnet alteration; K-feldspar ± hornblende alteration; Cu-Au mineralization and post-mineralization alteration and veining. Apatite from the paragenetically early apatite-calcite-quartz-garnet assemblage produce U–Pb ages of 1584 ± 22 Ma and 1587 ± 22 Ma, suggesting that the formation of apatite, and the maximum age of the Inter-lens is synchronous with D2 deformation of the Isan Orogeny and regional peak-metamorphic conditions. Apatite rare earth element-depletion trends display: (1) a depletion in rare earth elements evenly, corresponding with an enrichment in arsenic and (2) a selective light rare earth element depletion. Exposure to an acidic NaCl and/or CaCl2-rich sedimentary-derived fluid is responsible for the selective light rare earth element-depletion trend, while the exposure to a neutral to alkaline S, Na-, and/or Ca-rich magmatic fluid resulted in the depletion of rare earth elements in apatite evenly, while producing an enrichment in arsenic. We suggest the deposit experienced at least two hydrothermal events, with the first event related to peak-metamorphism (~1585 Ma) and a subsequent event related to the emplacement of the nearby (~1530 Ma) Williams–Naraku Batholiths. Brecciation resulted from competency contrasts between ductile metasedimentary rocks of the Inter-lens and surrounding shear zones against the brittle metavolcanic rocks that comprise the ore-bearing breccia, providing permeable pathways for the subsequent ore-bearing fluids. Full article
(This article belongs to the Special Issue Apatite and Ore Deposits)
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21 pages, 2932 KiB  
Article
Chemical Composition of Mn- and Cl-Rich Apatites from the Szklary Pegmatite, Central Sudetes, SW Poland: Taxonomic and Genetic Implications
by Adam Szuszkiewicz, Adam Pieczka, Bożena Gołębiowska, Magdalena Dumańska-Słowik, Mariola Marszałek and Eligiusz Szełęg
Minerals 2018, 8(8), 350; https://doi.org/10.3390/min8080350 - 14 Aug 2018
Cited by 9 | Viewed by 4562
Abstract
Although calcium phosphates of the apatite group (apatites) with elevated contents of Mn are common accessory minerals in geochemically evolved granitic pegmatites, their Mn-dominant analogues are poorly studied. Pieczkaite, M1Mn2M2Mn3(PO4)3X [...] Read more.
Although calcium phosphates of the apatite group (apatites) with elevated contents of Mn are common accessory minerals in geochemically evolved granitic pegmatites, their Mn-dominant analogues are poorly studied. Pieczkaite, M1Mn2M2Mn3(PO4)3XCl, is an exceptionally rare Mn analogue of chlorapatite known so far from only two occurrences in the world, i.e., granitic pegmatites at Cross Lake, Manitoba, Canada and Szklary, Sudetes, SW Poland. In this study, we present the data on the compositional variation and microtextural relationships of various apatites highly enriched in Mn and Cl from Szklary, with the main focus on compositions approaching or attaining the stoichiometry of pieczkaite (pieczkaite-like apatites). The main goal of this study is to analyze their taxonomical position as well as discuss a possible mode of origin. The results show that pieczkaite-like apatites represent the Mn-rich sector of the solid solution M1(Mn,Ca)2M2(Mn,Ca)3(PO4)3X(Cl,OH). In the case of cation-disordered structure, all these compositions represent extremely Mn-rich hydroxylapatite or pieczkaite. However, for cation-ordered structure, there are also intermediate compositions for which the existence of two hypothetical end-member species can be postulated: M1Ca2M2Mn3(PO4)3XCl and M1Mn2M2Ca3(PO4)3XOH. In contrast to hydroxylapatite and pieczkaite, that are members of the apatite-group, the two hypothetical species would classify into the hedyphane group within the apatite supergroup. The pieczkaite-like apatites are followed by highly Mn-enriched fluor- and hydroxylapatites in the crystallization sequence. Mn-poor chlorapatites, on the other hand, document local contamination by the serpentinite wall rocks. We propose that pieczkaite-like apatites in the Szklary pegmatite formed from small-volume droplets of P-rich melt that unmixed from the LCT-type (Li–Cs–Ta) pegmatite-forming melt with high degree of Mn-Fe fractionation. The LCT melt became locally enriched in Cl through in situ contamination by wall rock serpentinites. Full article
(This article belongs to the Special Issue Apatite and Ore Deposits)
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