Hydrothermal Dykes
Hydrothermal Dykes
A recent discovery at Thor is the occurrence of hydrothermal dykes that are exposed in the Thunder Zone. These dyke-like bodies are several meters in thickness. The origin of the dykes is unknown, but is most probably related to the emplacement of the Thor epithermal deposit. The hydrothermal dykes are resistant to weathering and form blocky outcrops. It is not uncommon for these dykes to be pyrite-bearing, and be extremely hard to break with a rock hammer. Zircons in the dykes have shown that the groundmass of this rock unit is sedimentary, and one age date has been retrieved showing that it is 1,425 MYA (+/- 33 MYA). The age of the zircon indicates that the groundmass of the hydrothermal dykes is sedimentary, having been derived from the North American Craton east of Thor. |