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

Abstract

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).

Boninite and boninite-series volcanics in northern Zambales ophiolite: Doubly-vergent subduction initiation along Philippine Sea Plate margins

“…The late Oligocene to early Miocene onset of true basinal sedimentation in the Central Valley Basin provides a minimum docking age between Zambales ophiolite and eastern Luzon (Bachman et al, 1983). The GPlates-based reconstruction presented here, using unfolded slab data (Wu et al, 2016), is essentially similar to the Philippine Sea Plate evolutionary models of Deschamps and Lallemand (2003). Although it is beyond the scope of this study to identify the nature of a pre-existing structural boundary as a transform fault or strike-slip extension of a subduction zone, we note that 25 both Zambales and IBM are orthogonal to the West Philippine Basin spreading center and the Cretaceous arc terranes in the overriding plate.…”

“…This gap was addressed by Wu et al (2016) southern Eurasia reveals that the Philippine Sea Plate was bordered by Cretaceous oceanic crust (the East Asian Sea) in its western margin. Paleomagnetic data derived from sites in the Philippine Sea Plate shows northward translation concomitant with clockwise rotation (Hall et al, 1995;Richter & Ali, 2015;Yamazaki et al, 2010) (Fig.…”

“…Adopting southerly paleolatitudes in consonance with the modelled Luzon translation history of Wu et al, (2016), we make 15 the case for the subduction initiation origin of Zambales ophiolite in the leading edge of the northwestward-moving, clockwise-rotating Philippine Sea Plate. In this scenario, the origin of Philippine Sea Plate boninites (IBM and Zambales) would be in a doubly-vergent subduction initiation setting (Fig.…”

“…Regional tectonic reconstructions predict the interaction of a pre-Eocene ocean basin located east of Eurasia and the western margin of the 5 Philippine Sea Plate (Wu et al, 2016). Coincidentally, aside from the IBM forearc region, the Dasol-Barlo locality in northern Zambales ophiolite is where middle Eocene boninitic rocks are also reported (Evans et al, 1991;Florendo & Hawkins, 1992;Hawkins & Evans, 1983).…”

Neotectonic interpretations and PS-InSAR monitoring of crustal deformations in the Fujian area of China

“…The faults in the study area such as Changle-Naoao and Yongan-Jinjiang fault zones are vertical and have horizontal striations and lateral dislocation drainages, which indicates that they are two groups of conjugate strike-slip faults resulting from oblique compressive stress from the collision between the Asiatic Plate and the Philippine Sea Plate [39]. This collision formed two groups of conjugate shear facture zones trending to the northeast and northwest ( Figure 7).…”