Collaborative Research: RUI: Deformation of dense crust and mantle beneath the Northern Andes from naturally deformed xenoliths

This project investigates a process where portions of Earth’s rigid outer shell sink into the deeper mantle. Understanding how the rigid outer shell sinks has important implications for the bulk composition of Earth’s continents, high topography such as plateaus and mountain ranges, the recycling of water or other volatiles into the deep earth, and the triggering of magmatism. The project serves the national interest through promoting the progress of science through the study of xenolith rocks, those brought up to the surface by volcanic eruptions, revealing how these rocks deform beneath the world’s longest active subduction zone. The project will further benefit society through the education of the STEM workforce, introducing students at a variety of levels to scientific research. The physical processes through which the lower lithosphere deforms in continental subduction systems and sinks into the underlying mantle remain obscure. Quantifying the strength of density-unstable crust – and the strength of the deforming mantle below these drips – is necessary to understand and quantify the geodynamics of these systems. This project will determine the rheological properties of a lithospheric section below the north Andean arc in southern Colombia, a thick and magmatically active mountain belt where crustal foundering is ongoing. In conjunction with experimentally derived flow laws and petrochronology, xenolith rheological properties will be used to develop a stress profile and a model for how rheological parameters influence lower-crustal loss via gravitational instabilities. The outcome of this project will contribute to the understanding of key processes in the tectonic processes at subduction plate boundaries. 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.