Mapping a Volcanogenic Massive Sulphide Deposit
Proof-of-concept trial of muon tomography, imaging the Price deposit — a multi-metal volcanogenic massive sulphide (VMS) ore body at Nyrstar’s Myra Falls underground mine.
Myra Falls Mine
PROJECT
British Columbia, Canada
LOCATION
Gallery
IDEON DETECTOR
Polymetallic volcanogenic massive sulfide
DEPOSIT TYPE
BACKGROUND
The Myra Falls underground mine was located under a provincial park in an environmentally sensitive area, and exploration drilling from surface was to be avoided. The Price deposit is a polymetallic volcanogenic massive sulfide (VMS), containing zinc, copper, lead and silver, providing good density contrast from the surrounding rock. The deposit is particularly amenable to imaging with muon tomography because it is located about 70 m below the surface, where muon intensity is quite high.
IDEON SOLUTION
A single muon detector was placed in a drift below and to the side of the known Price deposit, situated about 300 m below the surface under steep terrain. The detector was positioned for 15–20 days at seven different locations.
OUTCOME
The muon tomography results agreed well with measurements from underground drill core data. After a total exposure time of a few months, the radiographs from each detector location were incorporated in a 3D inversion.
Block model of density from the Price deposit. An iso-surface of the 3D density model (measured in g/cc) from muon data is shown by the pink surface, and the muon detector locations are shown by the green cubes (not to scale).