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Published September 16, 2015 | Published + Supplemental Material
Journal Article Open

Subduction initiation at relic arcs

Abstract

Although plate tectonics is well established, how a new subduction zone initiates remains controversial. Based on plate reconstruction and recent ocean drilling within the Izu-Bonin-Mariana, we advance a new geodynamic model of subduction initiation (SI). We argue that the close juxtaposition of the nascent plate boundary with relic oceanic arcs is a key factor localizing initiation of this new subduction zone. The combination of thermal and compositional density contrasts between the overriding relic arc, and the adjacent old Pacific oceanic plate promoted spontaneous SI. We suggest that thermal rejuvenation of the overriding plate just before 50 Ma caused a reduction in overriding plate strength and an increase in the age contrast (hence buoyancy) between the two plates, leading to SI. The computational models map out a framework in which rejuvenated relic arcs are a favorable tectonic environment for promoting subduction initiation, while transform faults and passive margins are not.

Additional Information

© 2015 American Geophysical Union. Received 18 JUN 2015; Accepted 11 AUG 2015; Accepted article online 14 AUG 2015; Published online 5 SEP 2015. This work is supported by the National Natural Science Foundation of China (91114203 and 41422402), National Science Foundation (EAR-1247022), and a postexpedition award for IODP Expedition 351. Wei Leng is also partially supported by the Fundamental Research Funds for the Central Universities (WK2080000053).

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Published - Leng_et_al-2015-Geophysical_Research_Letters.pdf

Supplemental Material - grl53346-sup-0001-TableS1.docx

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