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Models of mantle convection incorporating plate tectonics: The Australian region since the Cretaceous

Gurnis, Michael and Moresi, Louis and Müller, R. Dietmar (2000) Models of mantle convection incorporating plate tectonics: The Australian region since the Cretaceous. In: The History and Dynamics of Global Plate Motions. Geophysical Monograph. No.121. American Geophysical Union , Washington, DC, pp. 211-238. ISBN 9780875909790. https://resolver.caltech.edu/CaltechAUTHORS:20121121-080837329

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Abstract

We propose that the anomalous Cretaceous vertical motion of Australia and distinctive geochemistry and geophysics of the Australian-Antarctic Discordance (AAD) were caused by a subducted slab which migrated beneath the continent during the Cretaceous, stalled within the mantle transition zone, and is presently being drawn up by the Southeast Indian Ridge. During the Early Cretaceous the eastern interior of the Australian continent rapidly subsided, but must have later uplifted on a regional scale. Beneath the AAD the mantle is cooler than normal, as indicated by a variety of observations. Seismic tomography shows an oblong, slab-like structure orientated N-S in the transition zone and lower mantle, consistent with an old subducted slab. Using a three-dimensional model of mantle convection with imposed plate tectonics, we show that both of these well documented features are related. The models start with slabs dipping toward the restored eastern Australian margin. As Australia moves east in a hot spot reference frame from 130-90 Ma, a broad dynamic topography depression of decreasing amplitude migrates west across the continent causing the continent to subside and then uplift. Most of the slab descends into the deeper mantle, but the models show part of the cooler mantle becomes trapped within the transition zone. From 40 Ma to the present, wisps of this cool mantle are drawn up by the northwardly migrating ridge between Australia and Antarctica. This causes a circular dynamic topography depression and thinner crust to develop at the present position of the AAD. The AAD is unique within the ocean basins because it is the only place where a modern ridge has migrated over the position of long term Mesozoic subduction. Our study demonstrates the predictive power of mantle convection models when they incorporate plate tectonics.


Item Type:Book Section
Related URLs:
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http://dx.doi.org/10.1029/GM121p0211DOIArticle
ORCID:
AuthorORCID
Gurnis, Michael0000-0003-1704-597X
Moresi, Louis0000-0003-3685-174X
Müller, R. Dietmar0000-0002-3334-5764
Additional Information:© 2000 by the American Geophysical Union. We thank H. van Heijst for access to his tomographic models and A. Lenardic, C. Beaumont, and R. Pysklywec for helpful comments on this manuscript. This represents Contribution Number 8577 of the Division of Geological and Planetary Sciences, California Institute of Technology. Some of the work reported here was conducted as part of the Australian Geodynamics Cooperative Research Centre and is published with the consent of the Director, AGCRC.
Group:Seismological Laboratory
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Other Numbering System NameOther Numbering System ID
Caltech Division of Geological and Planetary Sciences8577
Series Name:Geophysical Monograph
Issue or Number:121
Record Number:CaltechAUTHORS:20121121-080837329
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20121121-080837329
Official Citation:Gurnis, M., L. Moresi, and R. Dietmar Müller (2000), Models of mantle convection incorporating plate tectonics: The Australian region since the Cretaceous, in The History and Dynamics of Global Plate Motions, Geophys. Monogr. Ser., vol. 121, edited by M. A. Richards, R. G. Gordon, and R. D. van der Hilst, pp. 211–238, AGU, Washington, D. C., doi:10.1029/GM121p0211
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:35593
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:21 Nov 2012 17:40
Last Modified:03 Oct 2019 04:29

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