Testing Mantle Convection Simulations with Paleobiology and Other
Stratigraphic Observations: Examples from Western North America
Abstract
Mantle convection plays a fundamental role in driving evolution of
oceanic and continental lithosphere. In turn it impacts a broad suite of
processes operating at or close to Earth’s surface including landscape
evolution, glacio-eustasy, magmatism and climate. A variety of
theoretical approaches now exist to simulate mantle convection. Outputs
from such simulations are being used to parameterise models of landscape
evolution and basin formation. However, the substantial body of existing
simulations has generated a variety of conflicting views on the history
of dynamic topography, its evolution and key parameters for modelling
mantle flow. The focus of this study is on developing strategies to use
large-scale quantitative stratigraphic observations to asses model
predictions and identify simulation parameters that generate realistic
predictions of Earth surface evolution. Spot measurements of uplift or
subsidence provide useful target observations but are often controlled
by tectonic processes, yet avoiding areas where tectonics have
influenced vertical motions is challenging. To address this issue, we
use large inventories of stratigraphic data from across North America
with contextual geophysical and geodetic data to constrain the regional
uplift and subsidence history. We demonstrate that a suite of fairly
typical simulations struggle to match the amplitude, polarity and timing
of observed vertical motions. Building on recent seismological advances,
we then explore strategies for understanding patterns of continental
uplift and subsidence that incorporate (and test) predicted evolution of
the lithosphere, asthenosphere and deep mantle. Our results demonstrate
the importance of contributions from the uppermost mantle in driving
vertical motions of continental interiors.