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| Titel |
Forced-folding by laccolith and saucer-shaped sill intrusions on the Earth, planets and icy satellites |
| VerfasserIn |
Chloé Michaut |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250140983
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| Publikation (Nr.) |
 EGU/EGU2017-4442.pdf |
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| Zusammenfassung |
| Horizontal intrusions probably initially start as cracks, with negligible surface deformation.
Once their horizontal extents become large enough compared to their depths, they make room
for themselves by lifting up their overlying roofs, creating characteristic surface deformations
that can be observed at the surface of planets.
We present a model where magma flows below a thin elastic overlying layer characterized
by a flexural wavelength Λ and study the dynamics and morphology of such a magmatic
intrusion. Our results show that, depending on its size, the intrusion present different shapes
and thickness-to-radius relationships. During a first phase, elastic bending of the overlying
layer is the main source of driving pressure in the flow; the pressure decreases as the flow
radius increases, the intrusion is bell-shaped and its thickness is close to being proportional to
its radius. When the intrusion radius becomes larger than 4 times Λ, the flow enters
a gravity current regime and progressively develops a pancake shape with a flat
top.
We study the effect of topography on flow spreading in particular in the case where the
flow is constrained by a lithostatic barrier within a depression, such as an impact crater on
planets or a caldera on Earth. We show that the resulting shape for the flow depends on the
ratio between the flexural wavelength of the layer overlying the intrusion and the depression
radius.
The model is tested against terrestrial data and is shown to well explain the
size and morphology of laccoliths and saucer-shaped sills on Earth. We use our
results to detect and characterize shallow solidified magma reservoirs in the crust of
terrestrial planets and potential shallow water reservoirs in the ice shell of icy satellites. |
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