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TitrePortable X-ray fluorescence to optimize stream sediment chemistry and indicator mineral surveys, case 1: carbonatite-hosted Nb deposits, Aley carbonatite, British Columbia, Canada
AuteurMackay, D A R; Simandl, G J
SourceGeological Fieldwork 2013, British Columbia Geological Survey Paper 2014-1; British Columbia Ministry of Energy, Mines and Petroleum Resources, Paper no. 2014-1, 2013 p. 183-194 (Accès ouvert)
LiensOnline - En ligne
Séries alt.Secteur des sciences de la Terre, Contribution externe 20120509
ÉditeurBritish Columbia Ministry of Energy, Mines and Natural Gas
Documentpublication en série
Mediapapier; en ligne; numérique
Lat/Long OENS-123.7667 -123.6833 56.5000 56.4167
Sujetsniobium; éléments d'indice; analyse chimique; géochimie des terres rares; tantale; carbonatites; pyrochlore; columbite
Illustrationslocation maps; photographs; tables; graphs
ProgrammeÉtude des gîtes des métaux rares, Initiative géoscientifique ciblée (IGC-4)
Résumé(disponible en anglais seulement)
The Aley carbonatite-hosted deposit is the most important Nb resource in the British Columbia alkaline province. Portable X-ray florescence (pXRF) was used effectively to determine concentrations of carbonatite pathfinder elements (Nb, Ta, La, Ce, Pr, Nd, Y, Th, U, Ba, and Sr) in stream sediments. Investigation of sediments of the unnamed creek ("Al creek") draining the Aley carbonatite area, indicates that the + 250 µm, + 125 µm, and + 63 µm size fractions contain high concentrations of carbonatite pathfi nder elements (Nb, Ta, La, Ce, Pr, Nd, U, and Th) relative to other size fractions. The + 125 µm fraction was chosen for systematic evaluation of the pathfinder element distribution in Al Creek sediments because it is suitable for chemical analysis and Quantitative Evaluation of Materials by Scanning electron microscopy (QEMSCAN). This method will be used in the second part of this study, which will concentrate on indicator minerals. The same samples enriched in pathfinder elements are expected to contain minerals characteristic of carbonatites such as pyrochlore, columbite-(Fe), fersmite, monazite-(Ce), rare earth element (REE)-bearing fl uorocarbonates, barite, and apatite. As expected, samples overlying the deposit and immediately downstream from the Aley carbonatite have the highest concentrations of pathfinder elements. Optical microscopy, electron microprobe (EMP), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and QEMSCAN studies of these samples are required to identify the most useful carbonatite indicator minerals and quantify their relative abundances with increasing distance from the deposit.