TY - JOUR
T1 - Interactions of scales of convection in the Earth's mantle
AU - Coltice, Nicolas
AU - Larrouturou, Gaspard
AU - Debayle, Eric
AU - Garnero, Edward
N1 - Funding Information:
We thank Barbara Romanowicz, Maxim Ballmer and Philippe Agard for comments and reviews that profoundly helped improve the manuscript. The research leading to these results has received funding from the European Research Council within the framework of the SP2-Ideas Program ERC-2013-CoG, under ERC grant agreement 617588 . Calculations were performed at P2CHPD Lyon. We thank Maëlis Arnould for the automatic detection of plumes used in Figs. 11 and 12 . We thank Vincent Perrier for helping on Fig. 6 .
Funding Information:
We thank Barbara Romanowicz, Maxim Ballmer and Philippe Agard for comments and reviews that profoundly helped improve the manuscript. The research leading to these results has received funding from the European Research Council within the framework of the SP2-Ideas Program ERC-2013-CoG, under ERC grant agreement 617588. Calculations were performed at P2CHPD Lyon. We thank Ma?lis Arnould for the automatic detection of plumes used in Figs. 11 and 12. We thank Vincent Perrier for helping on Fig. 6.
Publisher Copyright:
© 2018 Elsevier B.V.
PY - 2018/10/30
Y1 - 2018/10/30
N2 - The existence of undulations of the geoid, gravity and bathymetry in ocean basins, as well as anomalies in heat flow, point to the existence of small scale convection beneath tectonic plates. The instabilities that could develop at the base of the lithosphere are sufficiently small scale (< 500 km) that they remain mostly elusive from seismic detection. We take advantage of 3D spherical numerical geodynamic models displaying plate-like behavior to study the interaction between large-scale flow and small-scale convection. We find that finger-shaped instabilities develop at seafloor ages > 60 Ma. They form networks that are shaped by the plate evolution, slabs, plumes and the geometry of continental boundaries. Plumes impacting the boundary layer from below have a particular influence through rejuvenating the thermal lithosphere. They create a wake in which new instabilities form downstream. These wakes form channels that are about 1000 km wide, and thus are possibly detectable by seismic tomography. Beneath fast plates, cold sinking instabilities are tilted in the direction opposite to plate motion, while they sink vertically for slow plates. These instabilities are too small to be detected by usual seismic methods, since they are about 200 km in lateral scale. However, this preferred orientation of instabilities below fast plates could produce a pattern of large-scale azimuthal anisotropy consistent with both plate motions and the large scale organisation of azimuthal anisotropy obtained from recent surface wave models.
AB - The existence of undulations of the geoid, gravity and bathymetry in ocean basins, as well as anomalies in heat flow, point to the existence of small scale convection beneath tectonic plates. The instabilities that could develop at the base of the lithosphere are sufficiently small scale (< 500 km) that they remain mostly elusive from seismic detection. We take advantage of 3D spherical numerical geodynamic models displaying plate-like behavior to study the interaction between large-scale flow and small-scale convection. We find that finger-shaped instabilities develop at seafloor ages > 60 Ma. They form networks that are shaped by the plate evolution, slabs, plumes and the geometry of continental boundaries. Plumes impacting the boundary layer from below have a particular influence through rejuvenating the thermal lithosphere. They create a wake in which new instabilities form downstream. These wakes form channels that are about 1000 km wide, and thus are possibly detectable by seismic tomography. Beneath fast plates, cold sinking instabilities are tilted in the direction opposite to plate motion, while they sink vertically for slow plates. These instabilities are too small to be detected by usual seismic methods, since they are about 200 km in lateral scale. However, this preferred orientation of instabilities below fast plates could produce a pattern of large-scale azimuthal anisotropy consistent with both plate motions and the large scale organisation of azimuthal anisotropy obtained from recent surface wave models.
KW - Lithosphere
KW - Mantle convection
KW - Plate tectonics
KW - Seismology
KW - Small scale convection
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U2 - 10.1016/j.tecto.2017.06.028
DO - 10.1016/j.tecto.2017.06.028
M3 - Article
AN - SCOPUS:85021792961
SN - 0040-1951
VL - 746
SP - 669
EP - 677
JO - Tectonophysics
JF - Tectonophysics
ER -