Collaborative research: RUI: deformation of dense crust and mantle beneath the northern andes from naturally deformed xenoliths

The National Science Foundation Division of Earth Sciences awarded Amherst College, Trustees Of $222,397 on September 1, 2026, under the Geosciences program (CFDA 47.050) to investigate the rheological properties and deformation mechanisms of dense crust and mantle beneath the northern Andes through analysis of naturally deformed xenolith rocks.

The project examines how Earth's rigid outer lithosphere sinks into the mantle during continental subduction, focusing on a thick and magmatically active section below the North Andean Arc in southern Colombia. Researchers will determine the strength and deformation behavior of the lower crust and upper mantle by combining xenolith microstructural analysis with experimentally derived flow laws and petrochronology to develop stress profiles and models explaining how lithospheric foundering occurs through gravitational instabilities. Findings will contribute to understanding geodynamic processes at subduction plate boundaries and have broader implications for continental bulk composition, plateau and mountain range topography, deep-Earth volatile recycling, and magmatism triggering. The work will also provide educational opportunities for undergraduate students engaged in scientific research across multiple educational levels.

Performance occurs in Amherst, Massachusetts. The award obligates $222,397 with a period of performance from September 1, 2026, through August 31, 2029. The assistance type is Project Grant. This is a Research and Undergraduate Institution (RUI) collaborative research award.

Abstract

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.- subawards are not planned for this award.