NW Pacific-Panthalassa intra-oceanic subduction during Mesozoic times
from mantle convection and geoid models
Abstract
Pacific-Panthalassa plate tectonics back to Jurassic times are
recognized as the most challenging on Earth to reconstruct, due partly
to a large (>9000 km length) unconstrained area between the
Pacific and Laurasia (now NE Asia) during the Early Jurassic. We built
four contrasted NW Pacific-Panthalassa global plate reconstructions and
assimilated their velocity fields into global geodynamic models. We
compare our predicted mantle structure, synthetic geoid and dynamic
topography to Earth observations. P-wave tomographic filtering of
predicted mantle structures allowed for more explicit comparisons to
global tomography. Plate reconstructions that include intra-oceanic
subduction in NW Pacific-Panthalassa fit better to the observed geoid
and residual topography, challenging the Andean-style subduction along
East Asia. Our geodynamic models predict significant SE-ward lateral
slab advections within the NW Pacific basin lower mantle
(~2500 km from Mesozoic times to present), which can
confound “vertical slab sinking”-style restorations of past subduction
zone locations.