For the last 20 years, while “everybody else was largely focused on the Golden Triangle,” prospector Edward Balon was uncovering a rich new epithermal gold district just a few hours drive from Vancouver in southwestern British Columbia. His hard work and persistence in the Spences Bridge Gold Belt (SBGB) has paid off. For the last two years, it has been buzzing with exploration activity.

“It’s a historic mining district,” says Balon of the region surrounding Merritt where thousands of prospectors swarmed in 1857 after placer gold was discovered where the Nicoamen River flows into the Thompson River. “Everybody just assumed that others had thoroughly explored for the source of this gold, but that’s not the case.”

Balon was determined to find the source of the gold. He found several mentions of placer gold discoveries in historic literature, but no detailed geological mapping had been completed over the area, nor were any mineral deposits or showings recorded in the B.C. Geological Survey’s (BCGS) MINFILE database. The area is surrounded by significant porphyry copper deposits, but no epithermal gold-silver vein occurrences are associated with them.

Ed Balon and his Field Assistants’ great companions, October 2006

In the winter of 1999-2000, while employed by Almaden Minerals, Balon dove into historical records to learn more about the Spences Bridge Group, a narrow, north west-trending belt of Early Cretaceous volcanic rocks covering nearly 3,200 square kilometres from Princeton to Lillooet.

Several high-grade gold anomalies from stream sediment samples collected in the area and analysed as part of the Regional Geochemical Survey (RGS) caught his eye. The interesting results, part of the ongoing project RGS project launched in 1976 to collect and analyse lake and stream sediments from across the province, were collected in the Ashcroft map area in 1981. They were initially analysed for a few elements at the time but in 1994 were re-analysed for gold and the characteristic epithermal pathfinder elements: arsenic, antimony and mercury.

Making New Discoveries in Old Data

Prospector Edward Balon unearthed a new gold district in the Spences Bridge Gold Belt by ground-truthing anomalous samples that were collected and analysed as part of the Regional Geochemical Survey (RGS). The RGS began in 1976 and continues to support cost-effective greenfield exploration in the province today.

Initially, the RGS was jointly funded by the federal and provincial governments. Today, it is hosted and maintained by the BC Geological Survey and, in recent years, Geoscience BC has funded the collection of new samples in key areas of the province and reanalysis of previously collected samples using modern analytical techniques.

In June 2019, Geoscience BC announced a project to upgrade RGS mineralogical data in southeastern B.C. The project is collecting and analysing about 100 new bulk stream sediment samples from an area of the Penticton 1:250 000 map sheet that includes the communities of Beaverdell, Fauquier, Grand Forks and Greenwood.

“Indicator minerals recovered from these new samples will help identify geochemical anomalies and may reveal undiscovered mineralized sources and demonstrate a method to assess the geochemistry of large drainage areas using fewer samples,” says Geoscience BC vice- president, minerals Christa Pellett.

“If you have gold plus one of those, you are on the right track,” says Balon. “It was a good indicator that there was epithermal-style mineralization in that belt of rocks. But none of these anomalies had ever been explored because, in addition to there being no MINFILE occurrences, there were no mineral claims either. The whole belt was wide open.”

With the support of Almaden, Balon and colleague Wojtek Jakubowski began investigating promising RGS anomalies on the ground. In the summer of 2001, they discovered gold-bearing quartz veins and breccia float that showed classic epithermal textures and had significant gold grades, so they staked the Prospect Valley property for Almaden.

In the fall of 2004, a sampling team under Balon’s direction uncovered an outcrop of the first high-grade in-situ epithermal vein mineralization in the belt. He quickly staked this Skoonka prospect for Almaden, which optioned the property to Strongbow Exploration. The following year, Strongbow undertook the first drill program in the SBGB and intercepted 12.8 metres of 20.2 grams per tonne (g/t) gold, confirming high-grade epithermal gold in the belt.

These and other promising discoveries inspired a flurry of staking, drilling and other exploration activity in the SBGB between 2005 and 2008, but the global industry downturn largely halted exploration in the region until 2016.

Exploration in the SBGB resumed soon after Westhaven Ventures, where Balon is an adviser (having semi-retired in 2007), hired epithermal specialist Peter Fischl as its exploration manager in 2016. Fischl reviewed the historic drill records and studied clay alteration minerals at the Shovelnose property. He determined that previous explorers had modeled the mineralization in the wrong orientation.

With this new perspective, Westhaven drilled the highest-grade gold assays in the SBGB to date in 2018, including 1.65 meters of 175 g/t gold and 249 g/t silver, which included a 65-centimetre bonanza grade zone of 285 g/t gold. The discovery sparked a second staking rush in the belt.

Today, 86 per cent of the SBGB is held by Westhaven, which is advancing the Shovelnose, Prospect Valley, Skoonka and Skoonka North properties, and its strategic partner, Talisker Resources. Talisker is focused on high-density regional sampling and systematic mapping across the entire belt, following up on known anomalies to identify new drill targets.

“It is still early days for this whole district,” says Balon. “I believe that several significant, potentially economic epithermal gold-silver deposits other than the Shovelnose-South Zone will be discovered in future years.”

Author

  • Kylie Williams writes about science, technology, sustainability and responsibility in the mineral exploration and mining industry. Follow her on Twitter at @resourceswriter, or visit resourceswriter.com.