Coldwell Complex

The Coldwell Complex is a large circular gabbro and syenite intrusion within the Earth's crust. Located on the North Shore of Lake Superior in northwestern Ontario, Canada, it is the largest alkaline intrusion in North America with a diameter of 25 km (16 mi).

Coldwell Complex

The Coldwell Complex is a large circular gabbro and syenite intrusion within the Earth's crust. Located on the North Shore of Lake Superior in northwestern Ontario, Canada, it is the largest alkaline intrusion in North America with a diameter of 25 km (16 mi).