Fabrice Fontaine - Academia.edu (original) (raw)
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Papers by Fabrice Fontaine
Diversity of Hydrothermal Systems on Slow Spreading Ocean Ridges, 2010
The Yellowstone–East Snake River Plain hotspot track has been intensely studied since several dec... more The Yellowstone–East Snake River Plain hotspot track has been intensely studied since several
decades and is widely considered to result from the interaction of a mantle plume with the
North American plate. An integrated conclusive geodynamic interpretation of this extensive
data set is however presently still lacking, and our knowledge of the dynamical processes
beneath Yellowstone is patchy. It has been argued that the Yellowstone plume has delaminated
the lower part of the thick Wyoming cratonic lithosphere. We derive an original dynamic
model to quantify delamination processes related to mantle plume–lithosphere interactions.
We show that fast (∼300 ka) lithospheric delamination is consistent with the observed timing
of formation of successive volcanic centres along the Yellowstone hotspot track and requires
(i) a tensile stress regime within the whole lithosphere exceeding its failure threshold, (ii) a
purely plastic rheology in the lithosphere when stresses reach this yield limit, (iii) a dense
lower part of the 200 km thick Wyoming lithosphere and (iv) a decoupling melt horizon
inside the median part of the lithosphere. We demonstrate that all these conditions are verified
and that∼150 km large and∼100 km thick lithospheric blocks delaminate within 300 ka
when the Yellowstone plume ponded below the 200 km thick Wyoming cratonic lithosphere.
Furthermore, we take advantage of the available extensive regional geophysical and geological
observation data sets to design a numerical 3-D upper-mantle convective model. We propose a
map of the ascending convective sheets contouring the Yellowstone plume. The model further
evidences the development of a counter-flow within the lower part of the lithosphere centred
just above the Yellowstone mantle plume axis. This counter-flow controls the local lithospheric
stress field, and as a result the trajectories of feeder dykes linking the partial melting source
within the core of the mantle plume with the crust by crosscutting the lithospheric mantle. This
counter-flow further explains the 50 km NE shift observed between the mantle plume axis and
the present-day Yellowstone Caldera as well as the peculiar shaped crustal magma chambers.
Diversity of Hydrothermal Systems on Slow Spreading Ocean Ridges, 2010
The Yellowstone–East Snake River Plain hotspot track has been intensely studied since several dec... more The Yellowstone–East Snake River Plain hotspot track has been intensely studied since several
decades and is widely considered to result from the interaction of a mantle plume with the
North American plate. An integrated conclusive geodynamic interpretation of this extensive
data set is however presently still lacking, and our knowledge of the dynamical processes
beneath Yellowstone is patchy. It has been argued that the Yellowstone plume has delaminated
the lower part of the thick Wyoming cratonic lithosphere. We derive an original dynamic
model to quantify delamination processes related to mantle plume–lithosphere interactions.
We show that fast (∼300 ka) lithospheric delamination is consistent with the observed timing
of formation of successive volcanic centres along the Yellowstone hotspot track and requires
(i) a tensile stress regime within the whole lithosphere exceeding its failure threshold, (ii) a
purely plastic rheology in the lithosphere when stresses reach this yield limit, (iii) a dense
lower part of the 200 km thick Wyoming lithosphere and (iv) a decoupling melt horizon
inside the median part of the lithosphere. We demonstrate that all these conditions are verified
and that∼150 km large and∼100 km thick lithospheric blocks delaminate within 300 ka
when the Yellowstone plume ponded below the 200 km thick Wyoming cratonic lithosphere.
Furthermore, we take advantage of the available extensive regional geophysical and geological
observation data sets to design a numerical 3-D upper-mantle convective model. We propose a
map of the ascending convective sheets contouring the Yellowstone plume. The model further
evidences the development of a counter-flow within the lower part of the lithosphere centred
just above the Yellowstone mantle plume axis. This counter-flow controls the local lithospheric
stress field, and as a result the trajectories of feeder dykes linking the partial melting source
within the core of the mantle plume with the crust by crosscutting the lithospheric mantle. This
counter-flow further explains the 50 km NE shift observed between the mantle plume axis and
the present-day Yellowstone Caldera as well as the peculiar shaped crustal magma chambers.