Synchronous arc exhumation of the central and western Aleutian Islands at 7–5 Ma, Alaska, USA

The Aleutian arc, extending from the vicinity of the Kamchatka Peninsula in Russia to the Gulf of Alaska, has been used to investigate the subduction dynamics, structure, and magmatic evolution of island arcs. Yet, the way in which these processes relate to arc exhumation is untested, and knowledge of the timing and trend of exhumation across the Aleutian Islands is limited. Understanding the timing and magnitude of erosion has implications for island arc evolution, North Pacific tectonics, and sediment delivery to adjacent ocean basins. To test exhumation timing and spatiotemporal trends along >1500 km of the Aleutian arc, we applied apatite (U-Th)/He thermochronometry to 43 intrusive samples across six islands, from Attu to Unalaska. All samples were exhumed in the late Miocene to Pliocene regardless of pluton crystallization age, geochemistry, emplacement depth, or tectonic position along the arc, suggesting that parameters commonly associated with variations in arc volcanism (e.g., plate convergence rate and angle, slab dip, sediment input) did not drive this exhumation. Instead, we propose a pulse of widespread arc exhumation ca. 7−5 Ma related to deformation driven by Pacific plate rotation and potentially influenced by coeval Kula Ridge subduction and accretionary wedge formation. These results provide a direct link between increased Aleutian arc erosion and shifts in the late Miocene sedimentary and geochemical record in the North Pacific Ocean and Bering Sea. We propose that geodynamic processes, such as plate vector changes, can drive exhumation across large regions, consistent with accelerated exhumation observed across the circum-Pacific margin during this period.