Retrodiction Range of geodynamic earth models from twin experiments that account for model inconsistencies and limited resolution of present-day heterogeneity
Final Report Abstract
In summary, the main conclusions of this project are: For the first time, it was shown that it is possible to construct robust flow trajectories for highly vigorous global mantle flow in forward and inverse settings even for poorly known initial or final state conditions. To this end, knowledge of the horizontal surface velocity field, provided in practice through past plate motion models, is a crucial geodynamic model input. This means that the currently available time-span of such plate motion histories sets a limit on the temporal range of viable flow trajectories. It also suggests to undertake further work to improve past plate motion models for the benefit of geodynamic simulations. The likely existence of mismatched inversion parameters for adjoint mantle flow retrodictions means that one cannot judge the quality of computed mantle flow trajectories from the reduction of the final state misfit function alone. Specifically, performing a large number of adjoint iterations to reach a strong minimization of the final state misfit function may result in a poor match of the targeted initial state. Crucial independent constraints to appraise the quality of constructed flow trajectories are derived from flow-induced dynamic topographies. This is due to the fact that the computed model trajectories can be tracked and evaluated by their implied surface dynamic topography histories. It is feasible to derive geologic proxy data on past dynamic topographies from stratigraphic information by mapping the distribution of continental-scale hiatus surfaces. This calls for further research to enhance proxy data on past dynamic topographies from stratigraphic and other information, in close collaboration between geology and geodynamics. The ability to exploit constraints from dynamic topography, which is essentially a 2-D field, allows one to utilize metrics derived from meteorology for the quality assessment of flow trajectories. This project pioneered the introduction of such meteorological metrics to the field of geodynamics.
Publications
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Continent-scale Hiatus Maps for the Atlantic Realm and Australia since the Upper Jurassic and links to mantle flow induced dynamic topography. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 476(2242).
Hayek, Jorge Nicolas; Vilacís, Berta; Bunge, Hans-Peter; Friedrich, Anke M.; Carena, Sara & Vibe, Yulia
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Impact of model inconsistencies on reconstructions of past mantle flow obtained using the adjoint method. Geophysical Journal International, 221(1), 617-639.
Colli, L.; Bunge, H.-P. & Oeser, J.
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Global mantle flow retrodictions for the early Cenozoic using an adjoint method: evolving dynamic topographies, deep mantle structures, flow trajectories and sublithospheric stresses. Geophysical Journal International, 226(2), 1432-1460.
Ghelichkhan, S.; Bunge, H.-P. & Oeser, J.
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Evidence for active upper mantle flow in the Atlantic and Indo-Australian realms since the Upper Jurassic from hiatus maps and spreading rate changes. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 478(2262).
Vilacís, Berta; Hayek, Jorge N.; Stotz, Ingo L.; Bunge, Hans-Peter; Friedrich, Anke M.; Carena, Sara & Clark, Stuart
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Robust global mantle flow trajectories and their validation via dynamic topography histories. Geophysical Journal International, 234(3), 2160-2179.
Taiwo, A.; Bunge, H.-P.; Schuberth, B. S. A.; Colli, L. & Vilacis, B.
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A meteorology approach to assess mantle flow induced dynamic topography using object-based image processing methods. Physics of the Earth and Planetary Interiors, 351, 107195.
Taiwo, Ayodeji; Bunge, H.-P. & Craig, G.
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Dynamic topography and the planform of mantle convection since the Jurassic inferred from global continental hiatus maps. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 480(2302).
Vilacís, B.; Brown, H.; Bunge, H.-P.; Carena, S.; Hayek, J. N.; Stotz, I. L.; Wang, Z. R. & Friedrich, A. M.
