page_title: Mackenzie Large Igneous Province
section_title: Placement of the Muskox intrusion
hierarchical_section_title: Mackenzie Large Igneous Province / Geology / Magmatic history / Placement of the Muskox intrusion
caption_attribution_description: English: Geologic map of the Muskox intrusion and adjacent geologic groups.
context_page_description: The Mackenzie Large Igneous Province is a major Mesoproterozoic large igneous province of the southwestern, western and northwestern Canadian Shield in Canada. It consists of a group of related igneous rocks that were formed during a massive igneous event starting about 1,270 million years ago. The large igneous province extends from the Arctic in Nunavut to near the Great Lakes in Northwestern Ontario where it meets with the smaller Matachewan dike swarm. Included in the Mackenzie Large Igneous Province are the large Muskox layered intrusion, the Coppermine River flood basalt sequence and the massive northwesterly trending Mackenzie dike swarm.
  As a large igneous province, it is an extremely large area of related igneous rocks that were emplaced over an extremely short geological time span. The igneous rocks comprising the Mackenzie Large Igneous Province originated from processes not associated with normal plate tectonics and seafloor spreading. It is one of the several large igneous provinces scattered throughout the Canadian landscape, which can be thousands of kilometres in volume and area.
context_section_description: Adjacent to McGregor Lake in western Nunavut lies the massive Muskox intrusion. It remains as one of the largest and most studied layered intrusions on Earth, as well as one of the most valuable from an economic perspective. The intrusion represents the oldest igneous formation of the Mackenzie magmatic event, having formed between 1,905 and 1,155 million years ago. It maintains a triangular trough-shaped  magma chamber that extends 1.8 km (1.1 mi) below the surface. With a width of 20 km (12 mi) and a length of over 470 km (290 mi), the Muskox intrusion is overlain by a sequence of Coppermine flood basalts that remains 3 km (1.9 mi) thick.
  The Muskox intrusion can be separated into three sections, including an olivine gabbro feeder dike to the intrusion, another contact margin zone, and an upper layered series. Because of different levels of erosion and outcroppings of the Muskox intrusion at higher structural levels, north of the Coppermine River the overlying margin zone and layered series covers the feeder dike section. The layering series dips gently north as do the overlying Coppermine flood basalts. Weathering of the Muskox dipping sequence has exposed a cross-section through the entire dipping sequence, starting with the Coppermine flood basalts in the north above the roof of the magma chamber, down through the igneous layering of the Muskox intrusion and into the keel region of the intrusion and its intersection with the olivine gabbro feeder dike that forms the southernmost sector. The margin zone characterizes the western and eastern outer limits of the intrusion.
caption: Geologic map of the Muskox intrusion and adjacent geologic groups
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