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TitleDistribution of alteration facies, deposit types, metals, and critical minerals in metasomatic iron and alkali-calcic (MIAC) mineral systems
 
AuthorMontreuil, J F; Corriveau, LORCID logo; Blein, O; Ehrig, K; Hofstra, A; Lisitsin, V; Belperio, A; Schlegel, T; Mansur, E; Conliffe, J; Sparkes, G; Zhao, X F; Baldwin, G; Sappin, A AORCID logo; De Toni, A F; Goad, R
SourceGAC-MAC-IAH-CNC-CSPG Halifax 2022 May 15-18 abstracts; Geological Association of Canada-Mineralogical Association of Canada, Joint Annual Meeting, Abstracts Volume vol. 45, 2022 p. 160-161
Image
Year2022
Alt SeriesNatural Resources Canada, Contribution Series 20210668
PublisherGeological Association of Canada
MeetingGAC-MAC Halifax 2022; Halifax; CA; May 15-18, 2022
Documentserial
Lang.English
Mediapaper; on-line; digital
File formatpdf
SubjectsScience and Technology; mineralogy; metallic minerals; Nature and Environment; mineral deposits
ProgramTargeted Geoscience Initiative (TGI-6) Ore systems
Released2022 05 15
AbstractMetasomatic iron and alkali-calcic (MIAC) mineral systems are hydrothermal systems with regional extents of tens to hundreds of kilometers that are significant but challenging targets for mineral exploration. They can host iron oxide-copper-gold (IOCG) deposits, and a large variety of critical and precious metal deposits in which Ag, Au, Bi, Co, Cu, Fe, Mo, Ni, P, Pb, REE, U, W and Zn are the primary commodities or by-products. New research suggests that the diversity of mineral deposits occurring in MIAC systems relates to the evolution of voluminous saline fluid plume with diverse fluid and metal sources including the leaching of metals from compositionally diverse country rocks. Iron oxides (magnetite and hematite) prevail in many mineralization zones of MIAC systems to form iron oxide-rich mineralization and deposit types. However, in some MIAC systems, iron oxides occur in low abundance or are absent from the zones of mineralization. This can result in the formation of iron-oxide-poor to iron-poor mineralization and deposit types. In iron oxide-poor but iron-rich mineralization zones, iron resides in silicates, sulfides or carbonates. Conversely in iron-poor mineralization zones, alkali-calcic alteration forming variable quartz and carbonates is associated with metal deposition. A new framework based on alteration facies has been established to characterize the relation between mineralization and alteration in MIAC systems. Alteration facies are defined by systematic sets of mineral assemblages associated in time and space and formed under comparable physicochemical conditions. Facies are labeled using their diagnostic major element associations and high and low temperature ranges. Each alteration facies can be related with specific types of mineralization and metal assemblages. Using the alteration facies approach, a predictive model based on alteration mapping and the identification of major corridors of fluid circulation can be developed to guide mineral exploration in each system and define the types of deposits that may be in reach of exploration drilling. Examples from Australia, Canada, China, South America and the United States illustrate the diversity of deposit types possible in MIAC systems and reframe IOCG deposits as one of many deposit types with various major, minor and critical commodities. We recognize two groups of mineral deposits in MIAC systems: 1) Metasomatic Iron (MI) deposits that are associated with an iron-rich alteration facies, and 2) Metasomatic Alkali-Calcic (MAC) deposits that are associated with iron-poor alteration facies.
Summary(Plain Language Summary, not published)
Metasomatic iron and alkali-calcic (MIAC) mineral systems represent significant mineral exploration targets for critical and precious metal deposits. Silver, Au, Bi, Co, Cu, Fe, Mo, Ni, P, Pb, REE, U, W and Zn are primary commodities or by-products (e.g. iron oxide-copper-gold (IOCG) deposits). Iron oxide minerals (magnetite and hematite) precipitate with metals in most cases. In some systems, mineralization zones have low to no iron oxides. This can result in iron-rich deposit types where iron resides in silicates, sulfides or carbonates. Conversely, metals can precipitate with variable quartz and carbonate-bearing alkali-calcic alteration facies and form iron-poor mineralization. Examples from Canada, Australia, United States, China, and South America illustrate the diversity of iron-rich and iron-poor deposit types possible in MIAC systems, and the new deposit type classification proposed (grouped under Metasomatic Iron and Metasomatic Alkali-Calcic deposit types) reframe IOCG deposits as one of many critical metal deposit types of MIAC systems.
GEOSCAN ID329640

 
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