Title: Tectonic evolution of the northern Pacific plate and Pacific-Farallon Izanagi triple junction in the Late Jurassic and Early Cretaceous (M21-M10)
Abstract: Magnetic lineations in the northwestern Pacific, near the Shatsky Plateau, were interpreted to trace the tectonic history of the northern Pacific plate from the time of anomalies M21 to M10. At M22 time the Pacific-Farallon-Izanagi (P-F-I) triple junction was located southwest of the plateau and migrating north-northwest with respect to the Pacific plate. Shortly thereafter the stress field acting on the three plates changed significantly and the Pacific-lzanagi ridge reacted by pivoting 24° clockwise from M21 to M19 time. Several ridge propagation events occurred while the ridge adjusted to the new spreading regime. To the east of the M22 location of the junction it appears that this reorganization triggered a series of at least three ridge jumps along the Pacific-Farallon ridge. The geometry of magnetic isochron M21 suggests that several triple junctions existed simultaneously during the reorganization bordering one or more microplates. Differences in the spreading rate of the Japanese magnetic lineations north of the plateau imply that one microplate, which we call the Shatsky microplate, existed until about M15-M13 time. It was probably captured by either the Farallon or the Izanagi plate and subsequently destroyed by subduction. After M15 the P-F-I triple junction was reformed on seafloor that is now beneath the Shatsky Plateau. The junction drifted generally northeast, either in a ridge-ridge-ridge or in a ridge-fault-fault configuration, perhaps alternating between the two. From M11-M10 time the stress field on the three plates changed again and the Pacific-Farallon ridge southeast of the plateau reoriented 15° clockwise. At this time the P-F-I junction assumed a ridge-ridge-ridge geometry at the northeast end of the plateau.
Publication Year: 1988
Publication Date: 1988-12-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 96
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