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| Titel |
Rapid plate motion variations and continental uplift: a window on the history of asthenospheric flow |
| VerfasserIn |
Lorenzo Colli, Ingo Stotz, Hans-Peter Bunge, Mark Smethurst, Stuart Clark, Giampiero Iaffaldano, Andres Tassara, François Guillocheau |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250103991
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| Publikation (Nr.) |
 EGU/EGU2015-3413.pdf |
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| Zusammenfassung |
| Since the rifting of Gondwana ≈ 150 Myrs ago the South Atlantic Ocean experienced two
phases of fast spreading in Late Cretaceous and Oligocene-Miocene, separated by a period of
slow spreading around the K-T boundary and concluded by the recent slowdown since the
Messinian. At the same time, it is becoming clear that the topographic evolution of Africa is
characterized by two main periods of widespread uplift. These periods of uplift are co-eval
with the two phases of fast spreading. The present-day situation presents an oceanic
basin characterized by a strong topographic gradient with Africa being elevated and
South America being depressed by non-isostatic forcing. These observations — in
particular the fast time-scale of plate motion variations — are difficult to explain via
shallow tectonic forces acting in the lithosphere. However, they are completely
consistent with the fluid dynamics of a thin and low-viscosity asthenosphere. In
particular, they can be easily understood as the result of unsteady pressure-driven
flow in such a low-viscosity sublithospheric layer. Moreover, the idea of a thin
asthenosphere of low viscosity is corroborated by a number of observations and inferences,
ranging from seismic tomography to glacial isostatic adjustment to mineral physics. |
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