Deciphering Lithospheric and Deeper Mantle Contributions to the Surface History of the North American Arctic From the Unique Mantle to Surface Record of Kimberlites

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

Fundamental questions exist about the deep-time surface history of vast continental interior regions. In Arctic North America, diamondiferous kimberlite magmas of diverse age that bear fragments of rock entrained from deep in the Earth erupted through continental blocks of contrasting age, structure, and history. The disparate relationships provide the opportunity to evaluate the deep and shallow evolution across the region to illuminate how the histories at different depths are linked. This project will develop new and reinforce existing cross-disciplinary research relationships among U.S. and Canadian scientists studying processes at different depths in the Earth, train a CU-Boulder PhD student, and foster diversity through support of an underrepresented minority summer intern. A workshop will gather the project team and other members of the geologic, petrologic, and geodynamic communities to improve ties among these groups and enhance understanding of how deep Earth through surface processes are connected. This project's goals are to decipher the Phanerozoic surface history across the North American Arctic, identify relationships with the architecture and history of the lithospheric mantle, evaluate connections with the history of kimberlite magmatism, and consider the role of sublithospheric processes in these records. This will be accomplished by exploiting the unique mantle to surface record preserved within Arctic kimberlite pipes. Specifically, this project will (1) decipher the Arctic surface history and its spatial variability by integrating AHe data for kimberlite and basement samples with geologic constraints on the surface evolution borne by the pipes, (2) compare this surface record with the composition and evolution of the underlying mantle roots, which are being mapped by the project's University of Alberta collaborators through intensive study of these same kimberlites and their mantle xenolith suites, and (3) use a 3D-dynamic model of thermochemical convection to predict the Phanerozoic thermal evolution of the upper asthenosphere below North America. This project is jointly supported by the Petrology & Geochemistry, Geophysics, and Tectonics programs in the Division of Earth Sciences. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.