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TitleRegional mapping protocol, descriptive nomenclature and field database coding for iron oxide alkali-alteration (IOAA) ore systems and their IOCG, IOA and affiliated deposit types
AuthorCorriveau, L; deToni, A; Montreuil, J F; Wahl, J; Guilmette, C; Guilmette, S; Champagne, M; Dourlet, S
Source 2015 p. 1-3
Year2015
Alt SeriesEarth Sciences Sector, Contribution Series 20150013
PublisherGeological Association of Canada
Meeting2015 Joint Assembly AGU-GAC-MAC; Montreal; CA; May 3-7, 2015
Documentbook
Lang.English
Mediapaper; on-line; digital
File formatpdf
Subjectsmetallic minerals; economic geology; metamorphism, thermal; thermal alteration; iron oxides; iron ores; skarns; gold; copper; uranium; volcanogenic deposits; uranium deposits; skarn deposits; breccia deposits; contact metasomatic deposits; apatite; IOAA; IOCG; IOA
ProgramSouth Rae Province Bedrock/Surficial geology, GEM2: Geo-mapping for Energy and Minerals
AbstractIron oxide alkali-alteration (IOAA) ore systems create the largest metasomatic (hydrothermal alteration) systems known within the continental crust. The metasomatic processes culminate into:
1) iron, vanadium and specialised-metal ores within iron oxide±apatite (IOA or Kiruna-type) deposits,
2) base-, precious-, specialised- and nuclear-metal ores or by-products within magnetite-, magnetite to hematite- and hematite-group IOCG deposits, and
3) polymetallic ores within certain skarns and albitite-hosted uranium deposits.
Each of these deposit types is a consequence of the systemic development of metasomatic facies across the upper crust as its geotherms rise abnormally during regional-scale ascent of highly saline high-temperature fluid columns. From depth-to surface, fluids strongly react with and transform intensely and pervasively precursor rocks over about 30x5x10 km to form a series of alteration facies with their own, newly acquired, bulk- rock and mineral composition, mineral assemblages, grain sizes, textures and even structures. In addition, veins, stockworks and breccias abound and fills are most commonly associated with extensive alteration haloes. Alteration can replace, cross cut, be transitional to, juxtaposed upon, superimposed upon precursor rocks or earlier alteration types. In the process, some units may ¿disappear¿ from their stratigraphic sequence, being totally altered. Identifying and mapping these alterations are fundamental to modern geomapping for energy and minerals and for future exploration and deposit discovery as each alteration type vectors to its own deposit type and metal association.
This contribution illustrates the megascopic geological attributes of these metasomatic systems. Then it highlights the mapping protocols, nomenclature and field database codification system for mapping across the IOAA systems of the Labrador Trough (Québec) as part of the Geomapping for Energy and Minerals (GEM2) program in collaboration with its partner the Ministère des Ressources naturelles du Québec.
Summary(Plain Language Summary, not published)
This GEM2 - Hudson-Ungava project contribution illustrates the megascopic geological attributes of iron oxyde alkali alteration ore systems. Then it highlights the regional to local mapping protocols, the nomenclature and the field database codification system developed for the regional mapping across the Labrador Trough (Québec). This protocl is required as currently our field mapping tool is unable to capture the geology of such systems during our Geomapping for Energy and Minerals (GEM2) program. The codification system is being developed in collaboration with our GEM2 partner: the Ministère des Ressources naturelles du Québec. Identifying and mapping these alterations are fundamental to modern geomapping for energy and minerals and for future exploration and deposit discovery as each alteration type vectors to its own deposit type and metal association.
GEOSCAN ID296331