GRACE Gravity Data Constrain Ancient Ice Geometries and Continental Dynamics over Laurentia
M. E. Tamisiea,1*
J. X. Mitrovica,2
J. L. Davis1
The free-air gravity trend over Canada, derived from the Gravity
Recovery and Climate Experiment (GRACE) satellite mission, robustly
isolates the gravity signal associated with glacial isostatic
adjustment (GIA) from the longer–time scale mantle convection
process. This trend proves that the ancient Laurentian ice complex
was composed of two large domes to the west and east of Hudson
Bay, in accord with one of two classes of earlier reconstructions.
Moreover, GIA models that reconcile the peak rates contribute
25 to
45% to the observed static gravity field, which represents
an important boundary condition on the buoyancy of the continental
tectosphere.
2 Department of Physics, University of Toronto, 60 St. George Street, Toronto, ON M5S 1A7, Canada.
* Present address: Proudman Oceanographic Laboratory, 6 Brownlow Street, Liverpool L3 5DA, UK.
To whom correspondence should be addressed. E-mail: mtamisiea{at}cfa.harvard.edu
