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Inferring mantle properties with an evolving dynamic model of the Antarctica-New Zealand region from the Late Cretaceous

Spasojevic, Sonja and Gurnis, Michael and Sutherland, Rupert (2010) Inferring mantle properties with an evolving dynamic model of the Antarctica-New Zealand region from the Late Cretaceous. Journal of Geophysical Research B, 115 (B5). B05402. ISSN 0148-0227. doi:10.1029/2009JB006612.

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We show that time-dependent models of mantle upwellings above a cold downwelling in the New Zealand-Antarctica region since 80 Ma can explain anomalous geophysical observations: ~1.0 km of positive residual bathymetry at the Antarctica margin, a large Ross Sea geoid low, 0.5–0.9 km of excess tectonic subsidence of the Campbell Plateau since 80 Ma, and several seismic wave speed anomalies. Model results indicate that the largest mantle upwelling, centered in the Ross Sea, has an average temperature anomaly of 200°C and density anomaly of 0.6%, and it rose from midmantle depths at 80 Ma to a present depth of 400–1000 km. Anomalous Campbell Plateau subsidence requires a smaller hot anomaly evolving within the upper mantle under the region of the reconstructed Late Cretaceous Campbell Plateau. The excess subsidence of the plateau results from northward drift of New Zealand away from the dynamic topography high created by the smaller hot anomaly. To fit present-day geoid and residual topography observations, we require a large lower:upper mantle viscosity ratio of 100:1. We suggest that the distribution of temperature and viscosity is related to long-lived Gondwana subduction that accumulated high-density, high-viscosity lower mantle below a chemically altered upper mantle with anomalously low density and/or high temperature. Time-dependent observations enable constraints on absolute viscosities of 10^(23) Pa s and 10^(21) Pa s for the lower and upper mantle, respectively.

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Gurnis, Michael0000-0003-1704-597X
Additional Information:© 2010 American Geophysical Union. Received 12 May 2009; accepted 18 December 2009; published 14 May 2010. All calculations carried out on the Caltech Geosciences Supercomputer Facility were partially supported by NSF EAR‐0521699. This work was supported through the New Zealand Foundation for Research Science and Technology, the Caltech Tectonics Observatory (by the Gordon and Betty Moore Foundation), the National Science Foundation (EAR‐0609707 and EAR‐0810303), StatoilHydro, and an ExxonMobil Science grant (to S.S.). The original CitcomS software was obtained from Computational Infrastructure for Geodynamics ( This is contribution 10023 of the Division of Geological and Planetary Sciences and number 99 of the Tectonics Observatory, Caltech.
Group:Caltech Tectonics Observatory, Seismological Laboratory
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New Zealand Foundation for Research Science and TechnologyUNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
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Other Numbering System NameOther Numbering System ID
Division of Geological and Planetary Sciences10023
Caltech Tectonics Observatory99
Issue or Number:B5
Record Number:CaltechAUTHORS:20100603-113656937
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Official Citation:Spasojevic, S., M. Gurnis, and R. Sutherland (2010), Inferring mantle properties with an evolving dynamic model of the Antarctica‐New Zealand region from the Late Cretaceous, J. Geophys. Res., 115, B05402, doi:10.1029/2009JB006612.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:18551
Deposited On:23 Jun 2010 16:37
Last Modified:08 Nov 2021 23:44

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