INNOVATION November-December 2022

R esearchers at the BC Geological Survey are venturing into new technological territory by applying tried-and-true airborne geophysical methods—in miniature—to determine subglacial till composition for drift prospecting. At the same time, researchers at UBC and the University of Michigan are being inspired by nature to innovate in this same field of technology. Travis Ferbey, P.Geo., of the BC Geological Survey has been using remotely piloted aircraft systems (RPAS) technology for drift prospecting since 2019, with the RPAS enabling an intermediate scale of data collection between ground surveys and traditional airborne surveys. Ferbey said, “We started off by flying an RPAS that’s designed to collect high-quality air photos to create photogrammetric digital elevation models (DEMs). These are useful in Quaternary geology because we map the breaks in slope of surficial sediments to delineate landforms and interpret what sediments will be in those landforms.” For the past two summers, the team used RPAS geophysics—specifically magnetometry and gamma-ray magnetometry—to detect dispersal of mineralized lithologies in subglacial tills, formed from sediment deposited by moving glaciers. “Those measurements will characterize the rock that the till is derived from,” Ferbey said. Both the gamma-ray spectrometer and magnetometer are miniaturized versions of equipment used on fixed-wing aircraft or helicopters. The spectrometer measures gamma rays from the top 30 centimetres of the ground, and “if we ensure that we’re flying over a subglacial till, we’re measuring concentrations of potassium, equivalent uranium and equivalent thorium in that subglacial till,” said Ferbey. Potassium values could indicate potassic alteration from a porphyry deposit, which is an important target for BC mineral exploration. Spikes in uranium and thorium could indicate a carbonatite deposit, a potential source for some of the critical minerals needed to fuel a green economy. Ratios of potassium, uranium and thorium can characterize bedrock lithologies

if you’re flying over bedrock instead of till. The magnetometer can be used to measure magnetite content. Ferbey said, “Felsic to

P hoto : D r . V ikram B aliga /UBC

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