Airborne Geophysics for Rare Earth Element Exploration
French Title: Géophysique Aéroporté appliqué à l'exploration des Éléments de Terres Rares Olivier Ayotte Président REEX Exploration, Montréal, CanadaTimothée Fortin LaMothe B.Sc. Génie Géologique, REEX Exploration, Montréal, Canada
Abstract ID#: 35812
The Lake Leroux REE project is localized in the upper Gatineau region, Quebec Canada, 265 km NW of Montreal and 100 km N of Mont-Laurier.
Geological setting: The calc-silicate rocks of the Grenville Group are in contact with
Pre-Grenville granitic gneisses. The contact zone is cut by dikes of REE rich pegmatites.
Mineralogy synthesis: Magmatic rock, layered and probably metamorphosed , not magnetic, radioactive. Name: Syenite charnockitique, the mineralization is associated with hydrothermal alteration of pyroxene. The pyroxene are altered in a matrix of quartz and potassium feldspar.
On the outskirts, pyroxene contains thorium. At heart, it is altered in allanite (REE). The altered pyroxene in allanite is then cut by britholite veinlets. Hydrothermal mineralization in britholite and allanite (traces). Traces of hydrothermal zircon. Potassium Feldspar 70%, Quartz 15%, Pyroxene (thorium) (15%)
Geophysical Surveys: An Airborne Geophysical Survey covering 500 Line Kilometers of Aeromagnetic Gradiometer and Spectrometric was flown.
The Survey results indicate an N-S trending magnetic anomaly with a distinct break in the trench south of the central point. Samples taken from the edge of the discontinuity show elevated amounts of mineralization. To date ground fellow-up has uncovered more than 188 ground spectrometric anomalies. Richest samples were collected around the Hi/Low Magnetic Contrast, and high spectrometric counts area (Total Counts 500 cps and over).
Geochemistry: Samples shows up to 1, 6% TREO and up to 18% H+M+Y/TREO. More than 45 samples were analyzed by (ICP, ME-MS81) and 60 by XRF.
Ore Characterization : Bulk Samples (100 kg each) from 3 sites, will be analyzed by: " electron microprobe " to get a rough estimate of minerals present, " size- by- size" to get the basic levels for each size fraction based on ICP-MS and ICP-MP analyses , and possibly" QEMSCAN " to get an accurate estimate of minerals.