Paleomagnetism of seamounts in the West Philippine Sea as inferred from correlation analysis of magnetic anomalies

Ueda, Y.

doi:10.1186/bf03351794

Cited by 8 publications

(5 citation statements)

References 36 publications

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“…It has been argued that clockwise Philippine Sea plate rotations are consistent with Parece Vela and Shikoku basin seafloor spreading rate and direction changes [ Sdrolias et al , ]; however, a link between changes in relative motion and absolute plate rotation is not yet well established. On the other hand, Philippine Sea seamount magnetization vectors are not consistent with Philippine Sea clockwise rotations but instead suggest possible counterclockwise plate rotations [ Ueda , ].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2016

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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).

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Section: Introductionmentioning

confidence: 99%

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

et al. 2016

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“…From north to south, these comprise the Amami Plateau, the Daito Ridge, and the Oki-Daito Ridge, with models for their evolution having been presented in various studies (e.g., Tokuyama et al 1986;Tokuyama 2007;Ishizuka et al 2013). The latitude at which these bathymetric highs formed was investigated by Ueda (2004) using topographic and magnetic anomaly data. Paleolatitudes of 15.1°± 4.6°N for the Amami Plateau, 20.1°± 8.2°N for the Daito Ridge, and 4.4°± 11°S for the Oki-Daito Ridge were obtained, showing that these bathymetric highs initially formed south of their present positions and have since migrated northwards.…”

Section: Introductionmentioning

confidence: 99%

Wide-angle refraction experiments in the Daito Ridges region at the northwestern end of the Philippine Sea plate

et al. 2014

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Three large bathymetric highs (from north to south: the Amami Plateau, the Daito Ridge, and the Oki-Daito Ridge) originating from paleo-island arcs characterize the northwestern end of the Philippine Sea plate. We obtained 10 seismic refraction and multi-channel seismic reflection profiles across and along these bathymetric highs and obtained P wave velocity (Vp) models of the crust and the uppermost mantle. Although there are large variations in the crustal structure throughout this region, these bathymetric highs usually have a middle crust with Vp of 6.3 to 6.8 km/s, a lower crust with Vp of 6.8 to 7.2 km/s, a Pn velocity of 7.6 to 7.8 km/s, and a total crustal thickness of 15 to 25 km. These features are similar to those of the Izu-Ogasawara (Bonin)-Mariana island arc and the Kyushu-Palau Ridge, which are immature paleo-island arcs. However, the crust at the southwestern part of the Oki-Daito Ridge contains a relatively thin middle crust and a smaller total crustal thickness compared with other ridges in this region. In addition, we identified a deep reflector beneath the ridge, with these properties indicating a different origin, such as intraplate volcanism.

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“…However, the majority of the seamounts are magnetized in the normal direction. The seamounts in the KPR also show predominantly normal magnetizations, and no reversed seamount has been discovered (Ueda, 2004). Magnetic polarity intervals in the late Oligocene to Early Miocene are also characterized by short durations.…”

Section: Normal Polarity Bias Of Seamounts In the Nsrmentioning

confidence: 99%

“…Magnetic anomalies on these seamounts are mainly characterized by dipole type anomalies, suggesting normal magnetizations (Yamazaki et al, 1991;Ueda, 1996). The seamounts in the KPR also show predominant normal magnetizations, and to date no reversely polarized seamount has been discovered (Ueda, 2004). The KPR is thought to be generated prior to the opening of the Shikoku basin at approximately 25 Ma (Tomoda et al, 1975;Okino et al, 1994).…”

Section: Geological Backgroundmentioning

confidence: 99%

“…This method is effective for rapid estimations of magnetizations of edifices in the absence of polyg- onal models of topographic edifices (Ueda, 2004). When the topographic mesh data are given, the magnetic anomalies caused by the topographic model can be calculated using a 3-D inversion in the frequency domain, under the given directions of the magnetization field and the polarization of the magnetization of the edifices.…”

Section: Correlation Analysis Of Magnetic Anomaliesmentioning

confidence: 99%

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Magnetizations of the seamounts in the Izu-Ogasawara arc with special reference to the origin of their normal polarity biases

Ueda

2007

Earth Planet Sp

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Magnetizations of the seamounts in the Izu-Ogasawara arc are calculated using correlation analyses of magnetic anomalies and topographic data. The calculated results of the seamounts in the Sitito-Iozima ridge (present volcanic front) show normal magnetizations with a mean value of 5.10 ± 1.38 A/m. The results also show that the majority of the seamounts in the Nisi-Sitito ridge, which are Pliocene and Middle Miocene in origin, are magnetized in a normal magnetic field direction with a mean value of 2.74 ± 1.07 A/m. Seamounts in the Kyushu-Palau ridge, which are Oligocene in origin, also show predominantly normal polarities, with a mean of 2.67±0.71 A/m. For such a polarity bias to be explained by induced magnetization components (IM), including viscous remanent magnetization (VRM), the intensity of IM should be comparable to the mean of 2.74 A/m. However, no significant differences in the standard deviations of magnetization intensities are recognized between the seamounts in the Nisi-Sitito Ridge and those in the Sitito-Iozima Ridge, contrary to expectations if the normal polarity bias is IM in origin. Three-dimensional (3-D) multi-block model analyses are also applied to 25 seamounts having magnetization directions considerably different from those of the present magnetic field to estimate the normally and reversely magnetized volumes of the seamounts. The results show that 88% (22/25) of the seamounts have relatively greater volumes of normal magnetization compared to reverse magnetization. The IM component estimated from the 3-D multi-block model is a maximum of 0.66 A/m, which is too small to explain the observed normal polarity bias. A possible alternative explanation for the observed normal polarity bias may be enhanced volcanic activity during normal magnetic periods, although this is difficult to justify theoretically at the present time.

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Paleomagnetism of seamounts in the West Philippine Sea as inferred from correlation analysis of magnetic anomalies

Cited by 8 publications

References 36 publications

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

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

Wide-angle refraction experiments in the Daito Ridges region at the northwestern end of the Philippine Sea plate

Magnetizations of the seamounts in the Izu-Ogasawara arc with special reference to the origin of their normal polarity biases

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