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Back-arc opening and the mode of subduction

Uyeda, Seiya and Kanamori, Hiroo (1979) Back-arc opening and the mode of subduction. Journal of Geophysical Research B, 84 (B3). pp. 1049-1061. ISSN 0148-0227. doi:10.1029/JB084iB03p01049.

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Trench-arc systems (subduction zones) can be classified into two types depending on whether or not actively opening back-arc basins are associated with them. This suggests that subduction of an oceanic plate is not a sufficient condition for back-arc opening, though it may be necessary one. Mechanisms that cause the distinction between the two types have been investigated. Earthquake studies suggest that there is a significant difference in the mode of plate motion at interplate boundaries between the two types of trench-arc systems. Extreme cases are Chile, where plate motion is seismic, and the Marianas arc, where it is aseismic. This difference seems to indicate that the stress state in the back-arc area differs between the two types: compression in the Chilean type and tension in the Marianas type. This difference in the stress state is also manifested in other tectonic features, such as topography, gravity, volcanic activity, and crustal movement. Two possible mechanisms for the difference between the two types are suggested: (1) The nature of the contact zone between upper and lower plates changes from tight coupling (Chile) to decoupling (the Marianas) through the evolutionary process of subduction. The decoupling results in an oceanward retreat of the trench and back-arc opening. (2) The downgoing slab is anchored to the mantle, so that the position of a trench is also fixed with respect to the mantle. Since the motion in the mantle is slow compared to that of surface plates, it is the motion of the landward plate which controls the opening and nonopening of back-arcs.

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Kanamori, Hiroo0000-0001-8219-9428
Additional Information:© 1979 American Geophysical Union. Received February 7, 1978; revised August 21, 1978; accepted September 25, 1978. Paper number 8B1006. This study was conducted while Seiya Uyeda was at the Seismological Laboratory, California Institute of Technology, as a Sherman Fairchild Distinguished Scholar. We thank Seth Stein, Robert Geller, and Don Anderson for helpful comments on the manuscript. We also thank Seth Stein for his assistance in computing plate motions. This work was partially supported by a grant from the National Science Foundation, EAR76-14262. Contribution 3012 of the Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, 91125.
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Sherman Fairchild Distinguished Scholar grantUNSPECIFIED
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Caltech Division of Geological and Planetary Sciences3012
Issue or Number:B3
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Official Citation:Uyeda, S., & Kanamori, H. (1979). Back-arc opening and the mode of subduction. Journal of Geophysical Research: Solid Earth, 84(B3), 1049-1061. doi: 10.1029/JB084iB03p01049
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:58814
Deposited On:09 Jul 2015 21:46
Last Modified:10 Nov 2021 22:10

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