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Reconstruction of the tectonic evolution of the Pacific basin indicates a direct relationship between intraplate volcanism and plate reorganizations, which suggests that volcanism was controlled by fracturing and extension of the lithosphere. Middle Jurassic to Early Cretaceous intraplate volcanism included oceanic plateau formation at triple junctions (Shatsky Rise, the western Mid-Pacific Mountains) and a diffuse pattern of ocean island volcanism (Marcus Wake, Magellan seamounts) reflecting an absence of any well-defined stress field within the Pacific plate. The stress field changed in the Early Cretaceous when accretion of the Insular terrane to the North American Cordillera and the Median Tectonic arc to New Zealand stalled migration of the Pacific-Farallon and Pacific-Phoenix ocean ridges, leading to the generation of the Ontong Java, Manahiki, Hikurangi, and Hess Rise oceanic plateaus. Plate reorganizations in the Late Cretaceous resulted from the breakup of the Phoenix and Izanagi plates through collision of the Pacific-Phoenix ocean ridge with the southwest margin of the basin and development of island arc–marginal basin systems in the northwestern part of the basin. The Pacific plate nonetheless remained largely bounded by spreading centers, and intraplate volcanism followed preexisting lines of weakness in the plate fabric (Line Islands) or resulted from fractures generated by ocean ridge subduction beneath island arc systems (Emperor chain). The Pacific plate began to subduct under Asia in the Early Eocene as inferred from the record of accreted material along the Japanese margin. Further changes to the stress field at this time resulted from abandonment of the Kula-Pacific and the North New Guinea (Phoenix)–Pacific ridges and from development of the Kamchatkan and Izu-Bonin-Mariana arcs, leading to the generation of the Hawaiian chain as a propagating fracture. The final major change in the stress field occurred in the Late Oligocene as a result of breakup of the Farallon into the Cocos and Nazca plates, which caused a hiatus in Hawaiian volcanism; initiated the Sala y Gomez, Foundation, and Samoan chains; and terminated the Louisville chain. The correlations with tectonic events are compatible with shallow-source models for the origin of intraplate volcanism and suggest that the three principal categories of volcanism, intraplate, arc, and ocean ridge, all arise from plate tectonic processes, unlike in plume models, where intraplate volcanism is superimposed on plate tectonics.

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