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Quantifying the forces needed for the rapid change of Pacific plate motion at 6 Ma

Austermann, Jacqueline and Ben-Avraham, Zvi and Bird, Peter and Heidbach, Oliver and Schubert, Gerald and Stock, Joann M. (2011) Quantifying the forces needed for the rapid change of Pacific plate motion at 6 Ma. Earth and Planetary Science Letters, 307 (3-4). pp. 289-297. ISSN 0012-821X. doi:10.1016/j.epsl.2011.04.043.

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Studies have documented several rapid changes along the Pacific–North American, Pacific–Antarctic and Pacific–Australian plate boundaries in latest Miocene to earliest Pliocene time consistent with a sudden clockwise rotation of Pacific plate velocity relative to hotspots during this period. We test the hypothesis that this change in plate motion was initiated by cessation of subduction along the northern Melanesian arc due to the collision between the arc and the Ontong Java plateau. This hypothesis has long been formulated but never tested quantitatively. We use a geomechanical model of the lithosphere to determine the changes in plate boundary forces that are necessary to obtain the observed change in the Pacific plate motion. Our model results show that the change in motion can be explained by a clockwise rotation of the slab-related (basal-strength) component of plate driving force. The change of slab-related force from a post-6 Ma to a pre-6 Ma setting is perpendicular to the arc and points towards the Australian plate. The force per unit length is in the range of currently accepted values for subduction zones. Since there have been no other relevant changes at subduction zones along the Pacific plate boundary during the latest Miocene, we relate this change in slab-related force to the former southward-dipping Pacific plate slab along the northern Melanesian arc system which is now detached. Our model results suggest that rapid changes in plate motion can be triggered by slab detachment, with consequences for plate boundary processes even at great distances from the event.

Item Type:Article
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Stock, Joann M.0000-0003-4816-7865
Additional Information:© 2011 Elsevier B.V. Received 12 December 2010; revised 18 April 2011; accepted 28 April 2011. Editor: Y. Ricard. Available online 31 May 2011. We thank Y. Ricard and three anonymous referees for their thoughtful reviews. This work was initiated during Zvi Ben-Avraham's sabbatical at UCLA. We thank the Institute of Geophysics and Planetary Physics and the Department of Earth and Space Sciences at UCLA for their support. We thank G. Iaffaldano for pointing out the link to the Hawaiian-Emperor seamount chain. Funding for Jacqueline Austermann was provided by the Klaus Murmann Fellowship of the Foundation of German Business. California Institute of Technology, Division of Geological and Planetary Sciences, contribution number 10054.
Group:Seismological Laboratory
Funding AgencyGrant Number
UCLA Institute of Geophysics and Planetary PhysicsUNSPECIFIED
UCLA Department of Earth and Space SciencesUNSPECIFIED
Foundation of German Business Klaus Murmann FellowshipUNSPECIFIED
Subject Keywords:Pacific plate motion; plate driving forces; slab detachment; oceanic plateau collision; northern Melanesian arc
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Caltech Division of Geological and Planetary Sciences10054
Issue or Number:3-4
Record Number:CaltechAUTHORS:20110815-111337829
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Official Citation:Jacqueline Austermann, Zvi Ben-Avraham, Peter Bird, Oliver Heidbach, Gerald Schubert, Joann M. Stock, Quantifying the forces needed for the rapid change of Pacific plate motion at 6 Ma, Earth and Planetary Science Letters, Volume 307, Issues 3-4, 15 July 2011, Pages 289-297, ISSN 0012-821X, DOI: 10.1016/j.epsl.2011.04.043.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:24858
Deposited On:15 Aug 2011 20:16
Last Modified:09 Nov 2021 16:27

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