Are diamond-bearing Cretaceous kimberlites related to low-angle subduction beneath western North America?

Diamond-bearing Cretaceous kimberlites of western North America were emplaced 1000–1500 km inboard of the Farallon plate subduction margin and overlap with the development of the Western Interior Seaway, shut-down of the Sierra Nevada arc, and the Laramide orogeny. These events are consistent with a decrease in subduction angle along much of the margin, which placed the subducted Farallon plate in close proximity to the continental interior at the time of kimberlite magmatism. Our numerical models demonstrate that low-angle subduction can result from high plate convergence velocities and enhanced westward motion of North America. Further, rapid subduction allows hydrous minerals to remain stable within the cool interior of the subducting plate to more than 1200 km from the trench. Destabilization of these minerals provides a fluid source that can infiltrate the overlying material, potentially triggering partial melting and kimberlite/lamproite magmatism.

Research Highlights
► Cretaceous–Eocene kimberlites were emplaced in the western North America craton
► Kimberlite magmatism coincides with low-angle subduction of the Farallon plate.
► Numerical models show that hydrous minerals may be subducted below the craton.
► Slab dehydration may trigger melting of the craton lithosphere, producing kimberlites.