Publication Summary
Issue ID: GF2014-06
Title: Fine-tuning stream sediment chemistry and indicator mineral methodology in exploration for carbonatite-related REE targets, Wicheeda Lake, BC, Canada
Author(s): Mackay, D.A.R., Simandl, G.J.
Series Name: GeoFile
Publication Year: 2014
NTS Map Sheet(s): 093J/09
Place Keyword(s): British Columbia, central
Lat/Long (NSWE): 54.56, 54.49, -122.12, -122.03
Theme Keyword(s): indicator minerals, pathfinder elements, rare earth elements, specialty metals, portable x-ray fluorescence

The Wicheeda carbonatite-hosted deposit is one of the most promising rare earth element (REE) prospects within the British Columbia alkaline province. Portable x-ray fluorescence (pXRF) allows for determination of several pathfinder elements (Nb, Ta, REEs, Th, Ba, and Sr) in stream sediment samples collected downstream of this deposit. These samples are expected to contain indicator minerals derived from the main carbonatite complex such as monazite, REE-bearing carbonates and fluorocarbonates, pyrochlore, columbite-(Fe), barite-celestine, apatite, and others. Study of these samples indicates that the + 250 Ám, + 125 Ám, and + 63 Ám size fractions contain high concentrations of Nb, La, Ce, and Th relative to other size fractions. The + 125 Ám fraction was chosen for systematic chemical analyses and pathfinder element studies. Although there is no noticeable decreasing trend in pathfinder elements with increasing distance downstream, there is co-variation of Nb, Ta, La, Ce, Pr, Nd, Y, and Th. This reflects the presence of multiple mineral phases including pyrochlore, monazite-(Ce), REE-fluorocarbonates, and REE-carbonates. Mineralogical studies using optical microscopy, scanning electron microscopy (SEM), electron microprobe (EMP), and Quantitative Evaluation of Materials by Scanning electron microscopy (QEMSCAN) are required to identify and quantify minerals and their distributions downstream of the deposit.