1. Crustal-scale Deformation and Late Archean Terrane Suturing Keith Benn University of Ottawa kbenn@uottawa.ca Southeastern Superior Province Canada

2. Conclusions 1.2.7 Ga plate tectonics required to explain a documented terrane boundary 2.Probable accretion of oceanic LIP to margin of older crustal block 3.There is a very specific structural signature in the suture and in the accreted plateau 4.The structural signature is best explained by a crustal strength profile including a stiff lower crust, probably mafic granulites

3. SE Superior Province

4. SE Superior Province: Geology > 3000 Ma rocks below Pontiac (Carignan et al., Chem Geol, 1993)

5. Tectonic delamination

6. Tectonic delamination: why ? Geothermal gradient calculated incorporating crustal heat production (Sandiford et al., 2004; Afonso and Ranalli, 2004)

7. Magmatic modification NS

8. Two of the Tonalite Suites 2723 Ma 2713 Ma

9. Synmagmatic tectonic deformation of ca 2696 Ma Granodiorite Granodiorite 2700 Ma to 2696 Ma

10. Differing granitoid chemistry Provided by J.-F. Moyen

11. Remelting of diorites

12. Testing the model Positively identify surrounding terrane boundaries Crustal rheological profile –Strong lower crust (shear zones, faults) to be verified in the Kapuskasing zone Modified oceanic LIP –Detailed petrology / geochemistry of granitoids Define limits and nature of the old terrane

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