British Columbia's northwestern "Golden Triangle" region has been the focus of much of the province's mineral exploration due to its richness in metals. Courtesy of Pretium Resources.

As mineral exploration continues unabated by the COVID-19 pandemic, experts in the field congregated online from Jan. 18 to Jan. 22 at the Association for Mineral Exploration’s (AME) Roundup convention to become acquainted with the profession’s latest technologies and innovations.

“This year, there were many great technologies and techniques to help explorers look through till, and map chemical anomalies,” said Kendra Johnston, president and CEO of AME. “These ideas are used to search for vast porphyry deposits or classic epithermal deposits across B.C.”

Beyond the mountainous northwest of the province, explorers in British Columbia battle a blanket of glacial till and recent volcanic deposits of various thickness that obscure the location of ore deposits. In the final session of Roundup 2021, “Additions to the Geoscience Toolbox,” researchers explained multiple tools that work with, rather than against, this cover.

Using a method he called “instant exploration,” Alexei Rukhlov, provincial geochemist, B.C. Geological Survey (BCGS), described using sensors to sample mercury vapour in soil gas to delineate ore zones and fault structures that are buried under cover in real-time. Similarly, geochemist Ray Lett described a method for real-time soil gas testing using field-portable tools to map variations in soil gas carbon dioxide and oxygen concentrations to identify geological structures and concealed sulfide mineralization.

Testing the till itself, Alain Plouffe and colleagues described an automated method to analyze porphyry copper indicator minerals (PCIM) in a certain sand-size fraction of till to signal proximity to porphyry copper mineralization.

Mineral exploration tools guide our understanding of both ore deposit formations and their current place in the landscape. New models are being developed to help explorers and geoscientists understand B.C.’s rich porphyry deposits.

Related: The definitive text on the character and potential of the porphyry copper ore deposits and prospects of British Columbia, Yukon and Alaska

Gordon Clarke, director of the B.C. Mineral Development office, reported that 53 per cent of the exploration spending in B.C. in 2020 went to the northwest of the province, home of the Golden Triangle exploration and mining district around Stewart, B.C.

“The Golden Triangle has a world-class metal endowment,” said Bram van Straaten, senior minerals geologist, BCGS, during the “New Geoscience” session. “It has 220 million ounces of gold and 93 billion pounds of copper and very significant silver and molybdenum. Combined, they represent a total potential value of US$0.7 trillion. Only three per cent has actually been mined.”

Van Straaten and his colleagues presented a new model for ore deposit formation in the Golden Triangle to help explain why the area is so rich in metals. They delivered a “recipe” for ore deposit formation and identified the “sweet spot” where the structural, tectonic and sedimentary factors combine to form the rich ore deposits the region is known for, including the Red Chris and Brucejack mines.

In the nearby but less developed Toodoggone district, Farhad Bouzari addressed another exploration challenge: knowing where you are in a porphyry system. Bouzari applied porphyry index models developed by researchers at the Mineral Deposit Research Unit (MDRU) to indicate the vertical exposure level of porphyry-epithermal systems. By characterizing the extremes of porphyry deposits, explorers are better prepared to vector towards zones of copper mineralization at depth.

The value of this orebody information does not decline after discovery. IMDEX chief geoscientist David Lawie, who spoke in the keynote “Leading Through Change” session on the value of ore deposit knowledge for making informed decisions about mine development and infrastructure, said, “Having orebody knowledge earlier,… you can mine the deposit in a far more efficient way.”

Roundup presenters acknowledged the critical role exploration plays in refilling the project pipeline weakened by almost a decade of downturn and market instability. Sharing the tales of discovery, ore deposit models and exploration tools and techniques are a mainstay of the Roundup conference.