Meetasediments / Metavolcaniclastic Rocks

Roadcut showing carbonaceous alteration in the Jowett/Sharon Creek Formation. The Thor epithermal deposit is located approximately 10m below this roadcut, and is a graphic example of how hydrothermal fluids have produced carbonaceous alteration shells around epithermal veins.

Jowett/Sharon Creek Formation

Underlying the Broadview Formation is a very complex series of metavolcanics and metasedimentary rocks. These include greywackes, black shales and volcaniclastic rocks that form a complex succession of layered host rocks. Although various workers in the past have said there are two formation (the Jowett Formation and the Sharon Creek Formation), the rocks here are simply refered to as underlying metasediments/metavolcaniclastics. They can be graphitic or non-graphitic, depending on how for they are located from the I-1 Intrusive. In one hole completed at Thor in 2024, the lowermost series of rocks is referred to as the "Bomb Unit" as it contains elevated levels of graphite (4-5%).

The sequence is believed to host hydrocarbons that have been thermally altered in proximity to the epithermal deposit and the prospective porphyry target. Carbon and oxygen isotope chemistry has shown that the carbonaceous zones around the epithermal deposit have identical composition. The carbonaceous zones are important at Thor because they can be mapped using both ground and aeromagnetic geophysical surveys. The recently completed MT survey has provided evidence of a large 'donut' of conductive material that surrounds the porphyry target. This is interpreted to mean that the porphyry target has intruded into the Jowett/Sharon Creek Formation and converted the organic material into conductive carbonaceous material.

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