1. Tectonomagmatic Evolution of the Midcontinent Rift

2. North America
(Laurentia)
at 1.1 Ga

3. Continental Rifting-
The creation of ocean basins

4. Mantle Plumes and Flood Basalts

5. Magmatic Underplating of the Crust
A Consequence of Mantle Plume Magmatism
LIPs-Large Igneous Provinces

6. Simple Tectonic Model for the MCR

7. Evidence of a Starting Mantle Plume
Rapid early rates of volcanism
Large total volume of mafic magmatism (> 20 km volcanic edifice in central axis of rift)
εNd of mafic rocks = 0 to slightly +

8. Main Igneous Units of the MCR Nipigon Sills Coldwell Complex Logan
Osler Group
Duluth
Complex
Michipichoten
Island
Volcanics
Isle Royale Fault
Beaver Bay
Complex
Portage Lake volcanics
North Shore Volcanic Gp
Mamainse Pt Volcanics
Douglas Fault
Mellen
Complex
Powdermill Group
Chengwatana volcanics

9. Geophysical Evidence of Underplating

12. Lo-P
Hi-P
Differentiated
Basalts of the NSVG
Primitive Ol Tholeiite

19. Geochronology of the MCR
Hoaglund (2010)

21. Proposed Tectonomagmatic Model for the Midcontinent Rift

25. Evolve to an Ocean Basin?
Why Didn’t the MCR
Evolve to an Ocean Basin?
- Dissipation of the Plume
- Resurgence of Grenville Compression