Variation in crustal structure along the Kyushu-Palau Ridge at 15–21°N on the Philippine Sea plate based on seismic refraction profiles

Nishizawa, Azusa; Kaneda, Kentaro; Katagiri, Yasutaka; Kasahara, Junzo

doi:10.1186/bf03352711

Cited by 50 publications

(40 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A similar thin crust with a thin Layer 3 has also been reported in the Parece Vela Basin to the south of the SB (Nishizawa et al, 2007;Takahashi et al, 2008). The backarc basin crust of the eastern Philippine Sea plate is significantly thinner than both average oceanic crust, which is 7.1±0.8 km thick (White et al, 1992) and the typical oceanic crust recently surveyed in the NPB, which was produced with a fast spreading half-rate >8 cm/year at a mid-ocean ridge (Oikawa et al, 2010).…”

Section: Discussionmentioning

confidence: 61%

“…OBS receivers were deployed at a standard interval of 5 km. The procedure for data processing and velocity analysis was the same as that used by Nishizawa et al (2007Nishizawa et al ( , 2009. The OBS travel time data were modeled by tomographic inversion (tomo2D; Korenaga et al, 2000) and two-dimensional ray tracing using the graph method (Kubota et al, 2009), and field data were compared to synthetic seismograms (E3D; Larsen and Schultz, 1995).…”

Section: Data Acquisition and Modelingmentioning

confidence: 99%

See 1 more Smart Citation

Backarc basin oceanic crust and uppermost mantle seismic velocity structure of the Shikoku Basin, south of Japan

2011

Self Cite

View full text Add to dashboard Cite

Seismic refraction and reflection measurements were made along three profiles across the Shikoku Basin, one of the three backarc basins on the Philippine Sea plate. The P-wave velocity models show the presence of a very large horizontal irregularity related to the seamounts on the extinct spreading center, transition zones from the Shikoku Basin to Kyushu-Palau Ridge, and from the Shikoku Basin to the Izu-Ogasawara Island arc. However, the other areas were found to have features similar to those of a normal oceanic crustal model composed of oceanic Layer 2 with a high velocity gradient and Layer 3 with a small velocity gradient. The Shikoku backarc basin oceanic crust was found to be characterized by a thinner igneous crust, especially in Layer 3, and the azimuthal anisotropy in the uppermost mantle expected from the seafloor spreading was not detected.

show abstract

Section: Discussionmentioning

confidence: 61%

Section: Data Acquisition and Modelingmentioning

confidence: 99%

Backarc basin oceanic crust and uppermost mantle seismic velocity structure of the Shikoku Basin, south of Japan

2011

Self Cite

View full text Add to dashboard Cite

show abstract

“…3), which can be attributed to the level of maturity in arc crustal evolution , the amount of back arc extension (Nishizawa et al, 2007), and the magmatic production rate (Christeson et al, 2008). Mature island arc systems, such as the Izu-Bonin-Mariana system, have three crustal layers which were developed by partial melting of the initial immature basaltic arc crust .…”

Section: Island Arcs: Modern Examplesmentioning

confidence: 99%

“…The felsic mid-crustal unit is produced by repetitive anatexis of the mafic lower crust Rioux et al, 2010). Juvenile island arcs are believed to lack this felsic middle layer, as in the cases of the Lesser Antilles and Leeward Antilles (Magnani et al, 2009;Christeson et al, 2008) and parts of the Kyushu-Palau Ridge (Nishizawa et al, 2007). The mid-crustal layer of the mature Aleutian arc, on the other hand, is inferred to be of a more mafic than intermediate composition, based on the higher seismic velocities at depths of 11-20 km (Shillington et al, 2004).…”

Section: Island Arcs: Modern Examplesmentioning

confidence: 99%

Future accreted terranes: a compilation of island arcs, oceanic plateaus, submarine ridges, seamounts, and continental fragments

Tetreault

Buiter

2014

Solid Earth

View full text Add to dashboard Cite

Abstract. Allochthonous accreted terranes are exotic geologic units that originated from anomalous crustal regions on a subducting oceanic plate and were transferred to the overriding plate by accretionary processes during subduction. The geographical regions that eventually become accreted allochthonous terranes include island arcs, oceanic plateaus, submarine ridges, seamounts, continental fragments, and microcontinents. These future allochthonous terranes (FATs) contribute to continental crustal growth, subduction dynamics, and crustal recycling in the mantle. We present a review of modern FATs and their accreted counterparts based on available geological, seismic, and gravity studies and discuss their crustal structure, geological origin, and bulk crustal density. Island arcs have an average crustal thickness of 26 km, average bulk crustal density of 2.79 g cm −3 , and three distinct crustal units overlying a crust-mantle transition zone. Oceanic plateaus and submarine ridges have an average crustal thickness of 21 km and average bulk crustal density of 2.84 g cm −3 . Continental fragments presently on the ocean floor have an average crustal thickness of 25 km and bulk crustal density of 2.81 g cm −3 . Accreted allochthonous terranes can be compared to these crustal compilations to better understand which units of crust are accreted or subducted. In general, most accreted terranes are thin crustal units sheared off of FATs and added onto the accretionary prism, with thicknesses on the order of hundreds of meters to a few kilometers. However, many island arcs, oceanic plateaus, and submarine ridges were sheared off in the subduction interface and underplated onto the overlying continent. Other times we find evidence of terrane-continent collision leaving behind accreted terranes 25-40 km thick. We posit that rheologically weak crustal layers or shear zones that were formed when the FATs were produced can be activated as detachments during subduction, allowing parts of the FAT crust to accrete and others to subduct. In many modern FATs on the ocean floor, a sub-crustal layer of high seismic velocities, interpreted as ultramafic material, could serve as a detachment or delaminate during subduction.

show abstract

“…Many geological and geophysical investigations into the PSP have been reported (Seekins and Teng 1977;Seno and Maruyama 1984;Yu and Chang 1991;Oda and Senna 1994;Hall et al 1995;Nakamura and Shibutani 1998;Okino et al 1998Okino et al , 1999Yang and Wang 1998;Fujioka et al 1999;Yu et al 2000;Kamimura et al 2002;Okino and Fujioka 2003;Ohara 2006;Chang et al 2007;Ishihara and Koda 2007;Nishizawa et al 2007Nishizawa et al , 2011Isse et al 2009;Yeh et al 2013). These previous studies suggested that different tectonic/geological structures show distinct velocity structures.…”

Section: Introductionmentioning

confidence: 88%

The Crustal Thickness of the Philippine Sea Plate Derived from Gravity Data

Yen¹,

Lo²,

Yeh³

et al. 2015

Terr. Atmos. Ocean. Sci.

View full text Add to dashboard Cite

We constructed a new free-air gravity anomaly map of the Philippine Sea Plate (PSP) using ship-tracked gravity data from the National Geophysical Data Center (NGDC). Our results show that the isogals trend correlates well with the tectonic structures in the PSP. After removing the gravity induced by sea water from the free-air gravity data, we obtained the regional Bouguer gravity anomaly, which is later used to compute the Moho geometry in the PSP by applying the Parker-Oldenburg iterative method. Our results indicate that in the southern part of the West Philippine Basin (WPB) the crustal thickness is nearly homogeneous with a value of about 5 km, which implies that the WPB is quite stable. The low-amplitude and near-zero free-air gravity anomalies clearly indicate that the whole WPB, except at trenches and island arcs, is nearly in a state of isostatic equilibrium. The average crustal thickness of the Palau Kyushu Ridge (PKR) is more than 10 km. In the eastern PSP the crustal thickness gradually increases eastward. Our results also imply that a relatively thin and low density mantle exists beneath the Parece Vela Basin (PVB) as a consequence of back-arc spreading and serpentinized upwells of the thin crustal thickness.

show abstract

Variation in crustal structure along the Kyushu-Palau Ridge at 15–21°N on the Philippine Sea plate based on seismic refraction profiles

Cited by 50 publications

References 8 publications

Backarc basin oceanic crust and uppermost mantle seismic velocity structure of the Shikoku Basin, south of Japan

Backarc basin oceanic crust and uppermost mantle seismic velocity structure of the Shikoku Basin, south of Japan

Future accreted terranes: a compilation of island arcs, oceanic plateaus, submarine ridges, seamounts, and continental fragments

The Crustal Thickness of the Philippine Sea Plate Derived from Gravity Data

Contact Info

Product

Resources

About