The Need

BC’s South Central Region has an extensive history of mineral exploration and mine production dating back to the late 1800s. Updated geology maps with new geochronological data provide a framework for evaluating potential mineral targets.

Project Goals

The project has updated six 1:50,000 geological maps and analyzed 44 rock samples for age dating in the east half of the Penticton Map Sheet. Specifically, the project has:

• investigated high level intrusions (smaller, younger intrusions into the dominant local rock type);
• mapped areas of the Rock Creek graben, to recognize and trace favourable stratigraphic horizons;
• dated 44 rocks across the map area using U-Pb zircon and Ar-Ar mineral dating methods; and
• updated six previously published 1:50,000 maps with new age dates and resolved inconsistencies along map boundaries, established common colours and symbols, and correlated and standardized local formation names.

Project Benefits

As BC and Canada advance critical mineral and metal exploration, new research on areas of the province that have proved to be highly productive in the past could yield new, economic deposits.

This project has helped to identify new natural resource opportunities in BC’s South Central Region and can be used to inform resource development decisions. The project results can focus mineral exploration into prospective geological horizons known to exist in the area.

By recognizing, differentiating and dating smaller intrusions within this area, the project has provided a useful tool to help prospectors and mineral explorers differentiate between intrusion and the surrounding batholith.

Survey Area

The survey area is in BC’s South Central Region, between Greenwood to the west and Trail to the east. The Canada-US border runs along the southern boundary of the project area.

The nearby communities towns of Beaverdell, Boundary, Carmi, Grand Forks, Greenwood, Midway and Rock Creek in the Kootenay Boundary Regional District were founded on mining and have an extensive history of mineral exploration and production. Several in the area have been mined since gold was first discovered in 1884. For example, more than 25 past producers are recorded in the Greenwood mining camp. This includes the past producing Phoenix mine and several smaller mines, with over 100 mineral occurrences recorded.

How was the data collected?

Field observations and sample collection allowed for age dating and petrographic analyses on select samples. All age dating was conducted at the University of British Columbia.

What was found?

A large part of the Penticton Map Sheet is underlain by granitic and alkalic intrusive rocks that have variously been assigned to granodiorite of the ‘Nelson’ plutonic complex, granite of the Okanagan batholith or Coryell syenite. The basal Kettle and Marron formations of the Penticton Group host epithermal precious-metal deposits such as those extracted at the Greenwood and Franklin camps.

The dating of the basement intrusive rocks shows a complex history of episodic intrusive activity through the Jurassic, Cretaceous and Paleogene (particularly in the Eocene). This project has helped constrain the controls and the age of many lithologies in the area, including at the Franklin camp veins, the Lightning Peak Camp, the silver veins of Beaverdell, and the porphyry Midas, Tuzo Creek and Carmi deposits.

In summary, geological mapping and geochronological dating in the area have more clearly defined the relationship between the emplacement of the early Penticton Group volcanic rocks, brittle extensional faulting and intrusion of high-level Eocene plutonic rocks. The early Eocene was a period of extensive volcanism, graben formation, rapid uplift and intrusive activity. These conditions were conducive to the formation of mineral deposits, including epithermal precious-metal mineralization.

The project provides data to differentiate numerous small high-level stocks that may host porphyry and vein deposits in what was previously mapped as undifferentiated batholith. As these stocks are often difficult to recognize and are often overlooked, this project provides new insight into areas worthy of new exploration.