TY - JOUR
T1 - The influence of thermochemical convection on the fixity of mantle plumes
AU - McNamara, Allen K.
AU - Zhong, Shijie
N1 - Funding Information:
We thank Paul Tackley, Michael Manga, and Mark Jellinek for careful and insightful reviews. This work is supported by the David and Lucile Packard Foundation and NSF under grant number EAR 0134939. [SK]
PY - 2004/5/30
Y1 - 2004/5/30
N2 - A general feature of both isochemical and thermochemical studies of mantle convection is that horizontal plume velocities tend to be smaller than typical convective velocities, however, it is not clear which system leads to a greater fixity of mantle plumes. We perform two- and three-dimensional numerical calculations and compare both thermochemical and isochemical cases with similar convective vigor to determine whether presence of a dense component in the mantle can lead to smaller ratios of horizontal plume velocity to surface velocity. We investigate different viscosity and density contrasts between chemical components in the thermochemical calculations, and we perform isochemical calculations with both free-slip and no-slip bottom boundary conditions. We then compare both visually and quantitatively the results of the thermochemical and isochemical calculations to determine which leads to greater plume fixity. We find that horizontal plume velocities for thermochemical calculations are similar to those from isochemical calculations with no-slip bottom boundary conditions. In addition, we find that plumes tend to be more fixed for isochemical cases with free-slip bottom boundary conditions for two-dimensional calculations, however, in three dimensions, we find that plume fixity is similar to that observed in thermochemical calculations.
AB - A general feature of both isochemical and thermochemical studies of mantle convection is that horizontal plume velocities tend to be smaller than typical convective velocities, however, it is not clear which system leads to a greater fixity of mantle plumes. We perform two- and three-dimensional numerical calculations and compare both thermochemical and isochemical cases with similar convective vigor to determine whether presence of a dense component in the mantle can lead to smaller ratios of horizontal plume velocity to surface velocity. We investigate different viscosity and density contrasts between chemical components in the thermochemical calculations, and we perform isochemical calculations with both free-slip and no-slip bottom boundary conditions. We then compare both visually and quantitatively the results of the thermochemical and isochemical calculations to determine which leads to greater plume fixity. We find that horizontal plume velocities for thermochemical calculations are similar to those from isochemical calculations with no-slip bottom boundary conditions. In addition, we find that plumes tend to be more fixed for isochemical cases with free-slip bottom boundary conditions for two-dimensional calculations, however, in three dimensions, we find that plume fixity is similar to that observed in thermochemical calculations.
KW - Lower mantle
KW - Mantle convection
KW - Plumes
KW - Thermochemical convection
UR - http://www.scopus.com/inward/record.url?scp=2442693169&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=2442693169&partnerID=8YFLogxK
U2 - 10.1016/j.epsl.2004.03.008
DO - 10.1016/j.epsl.2004.03.008
M3 - Article
AN - SCOPUS:2442693169
SN - 0012-821X
VL - 222
SP - 485
EP - 500
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
IS - 2
ER -