Intra-oceanic subduction in North Pacific and its implication to the sudden change in Pacific Plate motion around 50 Ma
Abstract
The plate history in North Pacific since the Late Cretaceous remains debated. Traditional plate reconstructions suggest successive subduction of the Izanagi Plate and the Pacific Plate directly beneath the Northeast Asia. However, emerging evidence including paleomagnetism, structural geology and seismic tomography suggests intra-oceanic subduction existed in North Pacific since the Late Cretaceous to the Eocene. These intra-oceanic subduction zones might be intimately related to the kinematics of the Pacific Plate, including the change in Pacific Plate motion around 50 Ma which may have caused the Hawaiian-Emperor Bend (HEB). To test this hypothesis, we build high-resolution global mantle convection models based on alternative plate reconstructions in North Pacific to quantify the change in Pacific Plate motion around 50 Ma. We find that Izanagi Plate subduction, followed by demise of the Izanagi-Pacific ridge and Izu-Bonin-Mariana subduction initiation alone, is incapable of causing a sudden change in Pacific plate motion, challenging the conventional hypothesis on the mechanisms of Pacific Plate motion change. Instead, with the alternative intra-oceanic subduction model, the Paleocene slab pull from the Kronotsky subduction in North Pacific exerts a northward pull on the Pacific Plate, with its demise causing a sudden 30-35° change in Pacific Plate motion. We propose intra-oceanic subduction existed in North Pacific which have caused the sudden change in Pacific Plate motion. Such a scenario is consistent with available constraints from global plate circuits, palaeomagnetic data and geodynamic models.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFMGP44A..05H