Abstract
The timing and origin of Aleutian subduction initiation remain poorly constrained, yet they are central to understanding late Paleocene to early Eocene plate tectonic reorganization in the Pacific and its possible climatic consequences. Here, we use geochronologic and geochemical data obtained on western Aleutian arc samples from four basal submarine sequences, spanning ~700 km, to constrain Aleutian subduction initiation to ≥56 Ma. Early forearc lavas have similar compositions to forearc basalts erupted during the initial stages of Izu-Bonin-Mariana subduction in the western Pacific. Collision of the Olyutorsky Arc with Kamchatka-Koryak margin and subduction of the Izanagi-Pacific Ridge are likely to have triggered Aleutian subduction initiation and a change in absolute Pacific plate motion from WNW to N between 57 and 55 Ma, as shown with a GPlates model. Our study shows that Aleutian subduction initiation is a key event at the beginning of a major ~10 Myr plate reorganization in the circum-Pacific ending with Hawaii-Emperor-Bend formation. These tectono-magmatic events may have contributed to contemporaneous global climatic events in the late Paleocene and early Eocene.
Acknowledgements
Reinhard Werner is thanked for help obtaining funding and carrying out the cruises; S. Jung for providing XRF and D. Garbe-Schönberg for ICP-MS data; S. Hauff, K. Junge and U. Westernströer for analytical support; and Deep Sea Drilling Project (DSDP) and International Ocean Discovery Program (IODP) for sediment and IBM forearc reference samples.
Funding
K.H., M.P., and F.H. disclose support for the research of this work from the German Federal Ministry of Research, Technology and Space (BMFTR) [grants KALMAR 03G0640A and Bering 03G0249]; BJ from the National Science Foundation (NSF) [grants EAR-1753492 and OCE-1551657]; G.Y. from NSF [grants OCE-1551640 and EAR 1753518]; S.Z. from the Australian Research Council (ARC) [grant DE210100084]; D.M. and S.Z. from the AuScope National Collaborative Research Infrastructure System (NCRIS) program and GPlates Development. The remaining co-authors declare no relevant funding. Open Access funding enabled and organized by Projekt DEAL.
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Hoernle, K., Jicha, B., Portnyagin, M. et al. Tectonic and climatic implications of the Aleutian Arc initiation ≥56 million years ago. Nat Commun (2026). https://doi.org/10.1038/s41467-026-73363-y
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DOI: https://doi.org/10.1038/s41467-026-73363-y
