Study of multiparameter data on exploration drill core from the McLeod VMS deposit, Matagami mining district, Quebec

English Abstract:

The INRS mobile laboratory for the physical, chemical and mineralogical characterization of rocks acquires multiparameter data on exploration drill cores. The laboratory can measure nearly simultaneously and non-destructively the density, magnetic susceptibility, geochemistry and mineralogy of drill core, directly on their storage sites. This data supplements the visual core description made by the geologist and helps to discriminate spatially the lithologies and alterations related to the emplacement of VMS (or other) deposits.

The Bracemac-McLeod mine is located in the Matagami VMS district, in the northern part of the Abitibi Subprovince, Quebec. Three exploration drill cores were analyzed in summer 2014 and seven more are planned for summer 2015, for a total of over 6000 m spread over the McLeod deposit and up to 1 km to the east. Measurements are taken at 20-30 cm intervals, at specific spots determined by the geologist.

The large amount of data (several thousand measurement spots, over 20 variables) requires the use of statistical multivariate analysis methods to simultaneously interpret all data. In previous studies at Matagami (Fresia, Ross, Gloaguen & Bourke), cluster analysis was used to group the data point into classes (corresponding to the various lithologies defined by the geologist), on the basis of their physical and geochemical signatures. Also, Principal Component Analysis (PCA) helped determine the alteration zonation along the drill core and spatially between the studied drill cores. As part of the new MSc project, we will propose other multivariate methods, and attempt to develop exploration vectors using the composition or concentration of some mineral groups derived from near-infrared spectrometry.