Constraining Continental Dynamic Topography
Abstract
It is generally accepted that some component of Earth's topography is generated by changes in the spatial pattern of convection within the mantle. Compilations of oceanic residual depth measurements, which carefully account for sediment loading and crustal thickness variations, have demonstrated that this dynamic topography is characterized by wavelengths of ∼ 1000 ~km and maximum amplitudes of ± 2 ~km. However, variations in lithospheric density structure mean that estimates of continental residual elevation remain poorly constrained. In order to assess the recoverability of residual elevation estimates on the continents, we have compiled a database of ∼ 20000 published and unpublished spot measurements of continental crustal thickness from seismic refraction, reflection, tomographic and receiver function studies. A subset of these measurements are accompanied by estimates of 1-dimensional crustal seismic velocity structure as a function of depth, which can be exploited to calculate crustal densities using updated published relationships. We combine these crustal thickness and density estimates with a recent global map of lithospheric thickness. Our lithospheric columns are then isostatically balanced against a mid-oceanic ridge to yield estimates of residual elevation and accompanying uncertainties. Our results cohere with better-constrained, published observations of oceanic residual depth anomalies and geological markers of uplift and subsidence along continental margins.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMDI33B0019S
- Keywords:
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- 0545 Modeling;
- COMPUTATIONAL GEOPHYSICS;
- 8120 Dynamics of lithosphere and mantle: general;
- TECTONOPHYSICS;
- 8124 Earth's interior: composition and state;
- TECTONOPHYSICS;
- 8180 Tomography;
- TECTONOPHYSICS