Many north-trending shear zones intersect iron-rich tholeiitic basalts of the Arsenic Lake Formation.
These zones range in width from less than 1 m (3.3 ft) up to 5 m (16 ft), and might maintain a larger area of weakness that was tectonically active over the past billion years.
Evidence for early tectonism, likely related to volcanic activity, include the greater density of felsic dikes concentrated immediately around these zones.
An example is the north-south trending Big Dan Shear Zone situated near the former garbage dump of Temagami.
The felsic dikes near this zone are interpreted to represent a subvolcanic feeder system to the overlying felsic volcanic rocks.
It is probable that the dikes maintained a former zone of weakness now demonstrated by the shear zones.
Renewed tectonic activity along the Big Dan Shear Zone is manifested by offset of clastic sediments east of the Ontario Northland Railway.
This phase of tectonic activity displaced felsic dikes north of the exposed part of this shear zone.
However, considerable displacement of the dikes at this location is unknown.
The most recent phase of tectonic activity along the Big Dan Shear Zone resulted in the displacement of a Proterozoic dike composed of diabase, which intersects the zone.
A similar abundance of felsic dikes are adjacent to Arsenic Lake just west of Highway 11, indicating similar repetitive tectonism also occurred along that structural zone.
Therefore, the north-trending shear zones may have been active for at least a billion years.

Extending from Net Lake to Vermilion Lake lies a northeast-southwest trending high strain zone known as the Net Lake-Vermilion Lake Deformation Zone.
Because geologic mapping has not been done comprehensively throughout this zone, its exact width is unknown.
The expression of this deformation zone is clearly identifiable by the intense change in volcanic rocks of the TGB.
Volcanic units comprising the northwestern portion of the shear zone have shifted to the northeast while the volcanic rocks comprising its southeastern portion have shifted to the southwest.
Along the northeastern arm of Lake Temagami in Strathcona Township lies the Northeast Arm Deformation Zone.
This northeast-trending shear zone has not been studied in detail, but casual studies of many islands along the northeastern arm of Lake Temagami have shown that there is severe foliation and minor ferroan carbonate across an area about 1 km (0.62 mi) wide.
The Link Lake Deformation Zone, also known as the Link Lake Shear Zone, is an area of deformation 0.5 km (0.31 mi) wide and over 3 km (1.9 mi) long in Strathy Township.
It extends through Link Lake to east of Highway 11, but it is uncertain whether it extends west of Link Lake because no expression of it has been found in the Sherman Mine area.
Therefore, the Link Lake Shear Zone might be a northern extension of the Northeast Arm Deformation Zone further south.
Strain intensity of the Link Lake Shear Zone is diverse.
Generally, the greatest strain intensity is throughout pyroclastic rocks.
Extending from the western boundary of central Chambers Township through Tasse Lake to the east is the Tasse Lake Deformation Zone.
This deformation zone is roughly 3 km (1.9 mi) long and at least 0.5 km (0.31 mi) wide.
It is uncertain if this deformation zone extends east of Tasse Lake.
Many north-trending shear zones intersect iron-rich tholeiitic basalts of the Arsenic Lake Formation. These zones range in width from less than 1 m (3.3 ft) up to 5 m (16 ft), and might maintain a larger area of weakness that was tectonically active over the past billion years. Evidence for early tectonism, likely related to volcanic activity, include the greater density of felsic dikes concentrated immediately around these zones. An example is the north-south trending Big Dan Shear Zone situated near the former garbage dump of Temagami. The felsic dikes near this zone are interpreted to represent a subvolcanic feeder system to the overlying felsic volcanic rocks. It is probable that the dikes maintained a former zone of weakness now demonstrated by the shear zones. Renewed tectonic activity along the Big Dan Shear Zone is manifested by offset of clastic sediments east of the Ontario Northland Railway. This phase of tectonic activity displaced felsic dikes north of the exposed part of this shear zone. However, considerable displacement of the dikes at this location is unknown. The most recent phase of tectonic activity along the Big Dan Shear Zone resulted in the displacement of a Proterozoic dike composed of diabase, which intersects the zone. A similar abundance of felsic dikes are adjacent to Arsenic Lake just west of Highway 11, indicating similar repetitive tectonism also occurred along that structural zone. Therefore, the north-trending shear zones may have been active for at least a billion years.
Extending from Net Lake to Vermilion Lake lies a northeast-southwest trending high strain zone known as the Net Lake-Vermilion Lake Deformation Zone. Because geologic mapping has not been done comprehensively throughout this zone, its exact width is unknown. The expression of this deformation zone is clearly identifiable by the intense change in volcanic rocks of the TGB. Volcanic units comprising the northwestern portion of the shear zone have shifted to the northeast while the volcanic rocks comprising its southeastern portion have shifted to the southwest. Along the northeastern arm of Lake Temagami in Strathcona Township lies the Northeast Arm Deformation Zone. This northeast-trending shear zone has not been studied in detail, but casual studies of many islands along the northeastern arm of Lake Temagami have shown that there is severe foliation and minor ferroan carbonate across an area about 1 km (0.62 mi) wide. The Link Lake Deformation Zone, also known as the Link Lake Shear Zone, is an area of deformation 0.5 km (0.31 mi) wide and over 3 km (1.9 mi) long in Strathy Township. It extends through Link Lake to east of Highway 11, but it is uncertain whether it extends west of Link Lake because no expression of it has been found in the Sherman Mine area. Therefore, the Link Lake Shear Zone might be a northern extension of the Northeast Arm Deformation Zone further south. Strain intensity of the Link Lake Shear Zone is diverse. Generally, the greatest strain intensity is throughout pyroclastic rocks. Extending from the western boundary of central Chambers Township through Tasse Lake to the east is the Tasse Lake Deformation Zone. This deformation zone is roughly 3 km (1.9 mi) long and at least 0.5 km (0.31 mi) wide. It is uncertain if this deformation zone extends east of Tasse Lake.
Temagami Greenstone Belt