Parece Vela and Shikoku Basin extinct ridges

ID: 4-05

Ocean: Marginal basin
Spreading center type: Back-arc basin spreading center
Time of cessation: 17.6 Ma, chron C5Dy (Sdrolias et al., 2004)
Subsequent active spreading center: The Mariana Trough, situated to east of the Parece Vela extinct ridge and basin is active in the south
Cessation style: Later stages of spreading were thought to be at significantly lower spreading rates, suggesting a slow death (Chamot-Rooke et al., 1987).
Later deformation or volcanism: None evident

Review of previous studies:

The extinct spreading center that runs the length of the Parece Vela and Shikoku Basins, to the west of the presently active Marianas Trench has been well-studied (Mrozowski and Hayes, 1979; Chamot-Rooke, 1987; Sdrolias et al., 2004). Mrozowski and Hayes (1979) undertook a detailed study of the bathymetry, structure and magnetic anomalies in the basin and this led to the discovery of the extinct ridge axis. Chamot-Rooke et al. (1987) later re-interpreted the magnetic anomalies in the northern Shikoku Basin, suggesting that there was a marked change in the spreading direction of the basin during the later stages of opening, at about the time of anomaly 6B. More recent studies have investigated the life span of backarc basins generally (Stern and Dickinson, 2010) and the relative plate motions and subduction zone evolution in this complex region (Le Pichon et al., 1987; Sdrolias et al., 2004; Wallace et al., 2005).

Suggested reasons for cessation:

Stern and Dickinson (2010) proposed that the Parece Vela back-arc basin may have ceased and migrated to a new location in the east due to a reduction in the availability of hydrated melt after the basin reaches a critical width. They argue that once hydrated magmas are exhausted the ridge switches to a 'magma-poor' spreading style, derived from a dry mantle source, for a brief period before extinction (Stern and Dickinson, 2010).

References

Chamot-Rooke, N., Renard, V. and Le Pichon, X., 1987, Magnetic anomalies in the Shikoku Basin: a new interpretation, Earth and Planetary Science Letters, v. 83, p. 214-228.

Le Pichon, X., Iiyama, T., Chamley, H., Charvet, J., Faure, M., Fujimoto, H., Furuta, T., Ida, Y., Kagami, H., Lallemant, S., Leggett, J., Murata, A., Okada, H., Rangin, C., Renard, V., Taira, A., and Tokuyama, H., 1987, Nankai Trough and the fossil Shikoku Ridge: results of Box 6 Kaiko survey, Earth and Planetary Science Letters, v. 83, no. 1, p. 186-198.

Mrozokski, C. L., and Hayes, D. E., 1979, The evolution of the Parece Vela Basin, Eastern Philippine Sea, Earth and Planetary Science Letters, v. 46, p. 49-67.

Sdrolias, M., Roest, W. R. and Müller, R. D., 2004, An expression of Philippine Sea plate rotation: the Parece Vela and Shikoku Basins, Tectonophysics, v. 394, p. 69-86, doi:10.1016/j.tecto.2004.07.061.

Stern, R. J. and Dickinson, W. R., 2010, The Gulf of Mexico is a Jurassic backarc basin, Geosphere, v. 6, no. 6, p. 739-754.

Wallace, L. M., McCaffrey, Robert, Beavan, J., and Elis, S., 2005, Rapid microplate rotations and backarc rifting at the transition between collision and subduction, Geology, v. 33, no. 11, p. 857-860.

Shikoku Basin extinct ridge

Maps showing the location of extinct ridge segments

Depth profiles across the axes of extinct ridge segments

Gravity profiles across the axes of extinct ridge segments

Parece-Vela Basin extinct ridge

Maps showing the location of extinct ridge segments

Depth profiles across the axes of extinct ridge segments

Gravity profiles across the axes of extinct ridge segments