Philippine Sea and East Asian plate tectonics since 52 Ma constrained by new subducted slab reconstruction methods

• Published in: Journal of geophysical research. Solid earth Vol. 121; no. 6; pp. 4670 - 4741
• Main Authors: Wu, Jonny, Suppe, John, Lu, Renqi, Kanda, Ravi
• Format: Journal Article
• Language: English
• Published: 01.06.2016
• Subjects: Caroline Sea plate; Izu‐Bonin‐Marianas; Manus plume; Philippine Sea plate tectonics; subducted slabs; western Pacific subduction zones
• DOI: 10.1002/2016JB012923
• ISSN: 2169-9313

We reconstructed Philippine Sea and East Asian plate tectonics since 52 Ma from 28 slabs mapped in 3‐D from global tomography, with a subducted area of ~25% of present‐day global oceanic lithosphere. Slab constraints include subducted parts of existing Pacific, Indian, and Philippine Sea oceans, plus wholly subducted proto‐South China Sea and newly discovered “East Asian Sea.” Mapped slabs were unfolded and restored to the Earth surface using three methodologies and input to globally consistent plate reconstructions. Important constraints include the following: (1) the Ryukyu slab is ~1000 km N‐S, too short to account for ~20° Philippine Sea northward motion from paleolatitudes; (2) the Marianas‐Pacific subduction zone was at its present location (±200 km) since 48 ± 10 Ma based on a >1000 km deep slab wall; (3) the 8000 × 2500 km East Asian Sea existed between the Pacific and Indian Oceans at 52 Ma based on lower mantle flat slabs; (4) the Caroline back‐arc basin moved with the Pacific, based on the overlapping, coeval Caroline hot spot track. These new constraints allow two classes of Philippine Sea plate models, which we compared to paleomagnetic and geologic data. Our preferred model involves Philippine Sea nucleation above the Manus plume (0°/150°E) near the Pacific‐East Asian Sea plate boundary. Large Philippine Sea westward motion and post‐40 Ma maximum 80° clockwise rotation accompanied late Eocene‐Oligocene collision with the Caroline/Pacific plate. The Philippine Sea moved northward post‐25 Ma over the northern East Asian Sea, forming a northern Philippine Sea arc that collided with the SW Japan‐Ryukyu margin in the Miocene (~20–14 Ma). Key Points Twenty‐eight East Asia subducted slabs mapped from tomography and unfolded to constrain plate reconstructions Slab evidence for a subducted 8000 × 2500 km “East Asian Sea” that existed between the Pacific and Indian Oceans in the early Cenozoic Miocene arc‐arc collision between the northern Philippine Sea plate and the Ryukyu‐SW Japan Eurasian margin ~15–20 Ma