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

Abstract

[1] 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.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,

The ups and downs of North America: Evaluating the role of mantle dynamic topography since the Mesozoic

“…Among the above factors, the first two (density and viscosity) are the most commonly discussed ones for generating model discrepancies. Traditionally, the mantle density and viscosity structures are inferred mostly from geophysical inversions such as glacial isostatic adjustment [e.g., Haskell, 1935;Walcott, 1973;Mitrovica and Forte, 2004] and gravity/geoid modeling [e.g., Hager, 1984;King and Masters, 1992;Simons and Hager, 1997;Spasojevic et al, 2010]. The fact that a considerable amount of debates exists on these quantities likely reflects the intrinsic nonuniqueness of these geophysical inversions [Paulson et al, 2007].…”

“…These images provide potential links between the surface evolution and deep‐mantle dynamics. Last but not least, large‐scale geodynamic modeling has played a central role in establishing the connection between the present‐day mantle structure and the past geological records [ Bunge and Grand , ; Conrad and Gurnis , ; Xie et al ., ; Heine et al ., ; Zhang et al ., ], although considerable amount of debates still exist on the physical mechanisms and predicted history of North American vertical motion [ Müller et al ., ; Liu et al ., ; Spasojevic et al ., , ; Moucha et al ., , ; Liu and Gurnis , ; Liu et al ., ; Braun , ; Jones et al ., ; Rowley et al ., ; Liu , ].…”

“…Reviews of Geophysics 10.1002/2015RG000489 predicted history of North American vertical motion [Müller et al, 2008a;Spasojevic et al, 2009Spasojevic et al, , 2010Moucha et al, 2008Moucha et al, , 2009Braun, 2010;Jones et al, 2011;Rowley et al, 2013;Liu, 2014a].…”

Sea level and vertical motion of continents from dynamic earth models since the Late Cretaceous

“…Threedimensional models applied to Australia showed that anomalous Cretaceous vertical motions can be related to the movement of the continent over a slab associated with Gondwanaland-Pacific subduction while also explaining the anomalous geochemistry and geophysics of the present-day sea floor south of Australia (Gurnis et al, 1998;Gurnis et al, 2000b). Two episodes of long-wavelength tilting of the Russian platform during the Devonian to the Permian have been attributed to separate episodes of subduction (Mitrovica et al, 1996), whereas the excess subsidence of the Campbell plateau between 70 and 40 Ma have been related to the drift of New Zealand away from a dynamic topography high associated with a Ross Sea mantle upwelling (Sutherland et al, 2009;Spasojevic et al, 2010a). Global models of mantle flow driven by paleogeographically constrained subduction match patterns of flooding in the Middle Ordovician, Late Permian, and Early Cretaceous (i.e., periods of flooding during eustatic highs) (Gurnis, 1993), as well as the Cenozoic uplift and subsidence of North America, Australia, and Indonesia (Lithgow-Bertelloni and .…”

Cretaceous anomalous subsidence and its response to dynamic topography in the Songliao Basin, Northeast China

“…The dynamic topography associated with the subducting slab and its effects on mantle flow have been used to explain the subsidence and uplift of continents (Lithgow-Bertelloni and Gurnis et al, 1998;Burgess et al, 1997;Xie et al, 2006;Spasojevic et al, 2010;Liu et al, 2011).…”