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| Titel |
Fluctuations in seafloor spreading predicted by tectonic reconstructions and mantle convection models |
| VerfasserIn |
Nicolas Coltice, Maria Seton, Tobias Rolf, R. Dietmar Müller, Paul J. Tackley |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250076268
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| Zusammenfassung |
| The theory of plate tectonics theory has enabled possible the reconstruction of the ancient
seafloor and paleogeography. Over 50 years of data collection and kinematic reconstruction
efforts, plate models have improved significantly (Seton et al., 2012) although reconstructions
of ancient seafloor are naturally limited by the limited preservation of of very old seafloor. It
is challenging to reconstruct ancient ocean basins and associated plate boundaries for times
earlier than 200 Ma, since seafloor of this age is not preserved. This means we can
merely reconstruct only 5% of the history of the planet in this fashion. However,
geodynamic models can now help evaluate how seafloor spreading may evolve over
longer time periods, since recent developments of numerical models of mantle
convection with pseudo-plasticity can generate long-term solutions that simulate a
form of seafloor spreading (Moresi and Solomatov, 1998; Tackley, 2000a; Tackley,
2000b). The introduction of models of continental lithosphere further improves the
quality of the predictions: the computed distribution of seafloor ages reproduces the
consumption of young seafloor as observed on the present-day Earth (Coltice et al.,
2012).
The time-dependence of the production of new seafloor has long been debated and there is no
consensus on how much it has varied in the past 150My, and how it could have fluctuated
over longer time-scales. Using plate reconstructions, Parsons (1982) and Rowley (2002)
proposed the area vs. age distribution of the seafloor could have experienced limited
fluctuations in the past 150My while others suggest stronger variations would fit the
observations equally well (Seton et al., 2009. Here we propose to investigate the global
dynamics of seafloor spreading using state-of-the-art plate reconstructions and geodynamic
models. We focus on the evolution of the distribution of seafloor ages because fundamental
geophysical observations like mantle heat flow or sea level provide “ground-truth” for
modeling this parameter. Both kinematic reconstructions and geodynamic models suggest the
rate of production of new seafloor can vary by a factor of 3 over a Wilson cycle, with
concomitant changes of the shape of the area vs. age distribution. Geodynamic
models show seafloor production time-series contain fluctuations of time scales
exceeding 500My that depend on the strength of the lithosphere and the amount of basal
heating.
References
Coltice, N., Rolf, T., Tackley P.J., Labrosse, S., Dynamic causes of the relation between area
and age of the ocean floor, Science 336, 335-338 (2012).
Moresi, L., Solomatov, V., Mantle convection with a brittle lithosphere: Thoughts on the
global tectonic style of the Earth and Venus, Geophys. J. 133, 669-682 (1998).
Parsons, B., 1982, Causes and consequences of the relation between area and age of the ocean
floor, J. of Geophys. Res. 87, 289-302 (1982).
Rowley, D. B., History of Plate Creation 180 Ma to Present, Geol. Soc. of America Bull. 114,
927-933 (2002).
Seton, M., Gaina, C., Müller, R.D., and Heine, C., Mid Cretaceous Seafloor Spreading Pulse:
Fact or Fiction?, Geology, 37, 687-690 (2009).
Seton, M., Müller, R.D., Zahirovic, S., Gaina, C., Torsvik, T.H., Shephard, G., Talsma, A.,
Gurnis, M., Turner, M., Maus, S., Chandler, M. (2012), Global continental and ocean basin
reconstructions since 200 Ma, Earth Sci. Rev. 113, 212-270 (2012).
Tackley, P.J., Self-consistent generation of tectonic plates in time-dependent, three-dimensional
mantle convection simulations, part 1: Pseudoplastic yielding, Geoch. Geophys. Geosys. 1
(2000a).
Tackley, P.J., Self-consistent generation of tectonic plates in time-dependent, three-dimensional
mantle convection simulations, part 2: Strain weakening and asthenosphere, Geochem.
Geophys. Geosys. 1, (2000b). |
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