The influence of upper-plate advance and erosion on overriding plate deformation in orogen syntaxes
<p>Focused, rapid exhumation of rocks is observed at some orogen syntaxes, but the driving mechanisms remain poorly understood and contested. In this study, we use a fully coupled thermomechanical numerical model to investigate the effect of upper-plate advance and different erosion scenari...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-11-01
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| Series: | Solid Earth |
| Online Access: | https://www.solid-earth.net/9/1207/2018/se-9-1207-2018.pdf |
| Summary: | <p>Focused, rapid exhumation of rocks is observed at some orogen syntaxes, but
the driving mechanisms remain poorly understood and contested. In this study,
we use a fully coupled thermomechanical numerical model to investigate the
effect of upper-plate advance and different erosion scenarios on overriding
plate deformation. The subducting slab in the model is curved in 3-D,
analogous to the indenter geometry observed in seismic studies. We find that
the amount of upper-plate advance toward the trench dramatically changes the
orientation of major shear zones in the upper plate and the location of rock
uplift. Shear along the subduction interface facilitates the formation of a
basal detachment situated above the indenter, causing localized rock uplift
there. We conclude that the change in orientation and dip angle set by the
indenter geometry creates a region of localized uplift as long as subduction
of the down-going plate is active. Switching from flat (total) erosion to
more realistic fluvial erosion using a landscape evolution model leads to
variations in rock uplift at the scale of large catchments. In this case,
deepest exhumation again occurs above the indenter apex, but tectonic uplift
is modulated on even smaller scales by lithostatic pressure from the
overburden of the growing orogen. Highest rock uplift can occur when a strong
tectonic uplift field spatially coincides with large erosion potential. This
implies that both the geometry of the subducting plate and the geomorphic and
climatic conditions are important for the creation of focused, rapid exhumation.</p> |
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| ISSN: | 1869-9510 1869-9529 |