Abstract
The ca. 47 Ma Hawaiian-Emperor bend shows that early Cenozoic plate reorganization affected individual volcanic lineaments, but whether Pacific volcanism responded coherently at the basin scale has remained unknown. Fewer than 5% of Pacific Ocean seamounts have been aged radiometrically, and those ages cluster along accessible lineaments, biasing the basin-wide record toward lineament behavior. We used machine learning to predict ages for ~4300 seamounts and to reconstruct basin-wide volcanic evolution. Volcanism peaked in the Late Cretaceous, declined through the early Cenozoic, and reached a minimum at 42.5 ± 6.5 Ma, tracking a sustained ca. 85–43 Ma plate reorganization that simplified the basin from a multi-ridge to a single East-Pacific-Rise–dominated configuration. The apparent ca. 45 Ma concentration of dated seamounts records localized lineament volcanism during this quiet interval rather than a basin-wide peak. Both lineament and scattered seamount populations transitioned from diffuse to spatially organized patterns, indicating a coherent basin-wide volcanic response to plate reorganization and first-order control by ridge configuration on Pacific intraplate volcanism.