Dynamic topography and anomalously negative residual depth of the Argentine Basin

Shephard, Grace E.; Liu, L.; Müller, R. Dietmar; Gurnis, Michael

doi:10.1016/j.gr.2011.12.005

Cited by 22 publications

(13 citation statements)

References 34 publications

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“…Many residual topography models, although with large uncertainties, suggest a large‐scale negative dynamic topography around South America (Kaban et al, ; Panasyuk & Hager, ; Steinberger, ). Point‐wise residual topography observations also show a deep Argentine Basin (Figure a) that is consistent with mantle flow model predictions (Shephard et al, ). However, the amplitude of the negative long‐wavelength dynamic topography around South America is small (Figure b), and shallow density heterogeneities may exert additional contributions regionally (Rodríguez Tribaldos et al, ), making the recovery of long‐wavelength negative dynamic topography around South America more difficult.…”

Section: Discussionsupporting

confidence: 86%

Oceanic Residual Topography Agrees With Mantle Flow Predictions at Long Wavelengths

Yang

Moresi

Müller

et al. 2017

Geophysical Research Letters

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Dynamic topography, the surface deflection induced by sublithosheric mantle flow, is an important prediction made by geodynamic models, but there is an apparent disparity between geodynamic model predictions and estimates of residual topography (total topography minus lithospheric and crustal contributions). We generate synthetic global topography fields with different power spectral slopes and spatial patterns to investigate how well the long-wavelength (spherical degrees 1 to 3) components can be recovered from a discrete set of samples where residual topography has been recently estimated. An analysis of synthetic topography, along with observed geoid and gravity anomalies, demonstrates the reliability of signal recovery. Appropriate damping factors, which depend on the maximum degree in the spherical harmonic expansion that is used to fit the samples, must be applied to recover the long-wavelength topography correctly; large damping factors smooth the model excessively and suppress residual topography amplitude and power spectra unrealistically. Recovered long-wavelength residual topographies based on recent oceanic point-wise estimates with different spherical expansion degrees agree with each other and with the predicted dynamic topography from mantle flow models. The peak amplitude of the long-wavelength residual topography from oceanic observations is about 1 km, suggesting an important influence of large-scale deep mantle flow.

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Section: Discussionsupporting

confidence: 86%

Oceanic Residual Topography Agrees With Mantle Flow Predictions at Long Wavelengths

Yang

Moresi

Müller

et al. 2017

Geophysical Research Letters

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“…This reflects a group effort from many research fields that could be largely divided into geology (involving field data collection and analysis), geophysics (development of geophysical imaging techniques), and geodynamics (application of numerical modeling). Earlier works on recognizing and quantifying dynamic topography include modeling the long-wavelength gravity/geoid signals associated with subducted slabs [Hager, 1984] and lower mantle density anomalies [Hager et al, 1985;Hager and Clayton, 1989], the flooding history of Phanerozoic continental margins and interior [Gurnis, 1993;Heine et al, 2008], and abnormal subsidence and uplift of continents such as North America [e.g., Mitrovica et al, 1989; Lithgow-Bertelloni and Gurnis, 1997;Spasojevic and Gurnis, 2012], Africa [e.g., Lithgow-Bertelloni and Silver, 1998;Gurnis et al, 2000;Conrad and Gurnis, 2003;Moucha and Forte, 2011], Australia [e.g., Gurnis et al, 1998;DiCaprio et al, 2009], and South America [e.g., Dávila et al, 2010;Dávila and Lithgow-Bertelloni, 2013;Shephard et al, 2010Shephard et al, , 2012aFlament et al, 2014].…”

Section: Introductionmentioning

confidence: 99%

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

Liu

2015

Reviews of Geophysics

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The driving force for transient vertical motions of Earth's surface remains an outstanding question. A main difficulty lies in the uncertain role of the underlying mantle, especially during the geological past. Here I review previous studies on both observational constraints and physical mechanisms of North American topographic evolution since the Mesozoic. I first summarize the North American vertical motion history using proxies from structural geology, geochronology, sedimentary stratigraphy, and geomorphology, based on which I then discuss the published physical models. Overall, there is a progressive consensus on the contribution of mantle dynamic topography due to buoyancy structures associated with the past subduction. At the continental scale, a largely west‐to‐east migrating deformation pattern suggests an eastward translation of mantle dynamic effects, consistent with models involving an eastward subduction and sinking of former Farallon slabs since the Cretaceous. Among the existing models, the inverse model based on an adjoint algorithm and time‐dependent data constraints provides the most extensive explanations for the temporal changes of North American topography since the Mesozoic. At regional scales, debates still exist on the predicted surface subsidence and uplift within both the western and eastern United States, where discrepancies are likely due to differences in model setup (e.g., mantle dynamic properties and boundary conditions) and the amount of time‐dependent observational constraints. Toward the development of the next‐generation predictive geodynamic models, new research directions may include (1) development of enhanced data assimilation capabilities, (2) exploration of multiscale and multiphysics processes, and (3) cross‐disciplinary code coupling.

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“…A warning message will be displayed if a dynamic topography model is selected whose starting age is younger than the oldest unit at a given site or younger than the rift initiation age supplied for a site on continental crust. This subsidence is driven by the westward motion of the South American Plate over the mantle, overriding previously subducted material of the Farallon Plate now sinking in the mantle underneath this region (Shephard et al, 2012), progressively drawing down the surface. Dynamic topography models are subject to many uncertainties, reflecting our incomplete knowledge of deep Earth structure and evolution.…”

Section: Examples Of Pybacktrack Usementioning

confidence: 99%

“…Dynamic topography models are subject to many uncertainties, reflecting our incomplete knowledge of deep Earth structure and evolution. Strong independent evidence for a regional drawdown of this region is provided by the adjacent Argentine Basin which has a well-known negative depth anomaly (Hohertz & Carlson, 1998;Shephard et al, 2012). Any given geodynamic model is a greatly simplified representation of the Earth, and depends on particular initial and boundary conditions, assumptions of the rheology of the deep Earth and particular modeling philosophies and implementations.…”

Section: Examples Of Pybacktrack Usementioning

confidence: 99%

“…Models M1-M4 predict dynamic subsidence of the region in the order of 150-200 m over the last 55 Myr. This subsidence is driven by the westward motion of the South American Plate over the mantle, overriding previously subducted material of the Farallon Plate now sinking in the mantle underneath this region (Shephard et al, 2012), progressively drawing down the surface. Model M1, which is a hybrid backward-forward model, incorporating a present-day density model of the mantle derived from seismic tomography as well as a forward-modeled subduction history through time (Spasojevic & Gurnis, 2012), captures this coupling of South America to a ''slab burial ground''.…”

Section: Examples Of Pybacktrack Usementioning

confidence: 99%

See 1 more Smart Citation

PyBacktrack 1.0: A Tool for Reconstructing Paleobathymetry on Oceanic and Continental Crust

Müller

Cannon

Williams

et al. 2018

Geochem Geophys Geosyst

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The pyBacktrack software package allows the backtracking of the paleo‐water depth of ocean drill sites, providing a framework for reconstructing the accumulation history of sediment components through time. The software incorporates the effects of decompaction of common marine lithologies and allows backtracking of sites on both oceanic and continental crust. Backtracking on ocean crust is based on a user‐selected lithospheric age‐depth model and the present‐day unloaded basement depth. Backtracking on continental crust is based on syn‐rift and post‐rift subsidence that is modeled using the total sediment thickness at the site and the timing of the transition from rifting to thermal subsidence. On sites that did not penetrate basement, the age‐coded stratigraphy is supplemented with a synthetic stratigraphic section that represents the undrilled section, whose thickness is estimated using a global sediment thickness map. This is essential for estimating the decompacted thickness of the total sedimentary section, and thus bathymetry, through time. PyBacktrack further allows the consideration of the effects of mantle‐convection driven dynamic topography on paleo‐water depth. The user can select one of the dynamic topography models bundled with pyBacktrack or add other models. PyBacktrack runs on all platforms with a Python 2.7 and a pyGPlates installation and is available via Github.

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Dynamic topography and anomalously negative residual depth of the Argentine Basin

Cited by 22 publications

References 34 publications

Oceanic Residual Topography Agrees With Mantle Flow Predictions at Long Wavelengths

Oceanic Residual Topography Agrees With Mantle Flow Predictions at Long Wavelengths

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

PyBacktrack 1.0: A Tool for Reconstructing Paleobathymetry on Oceanic and Continental Crust

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