Tectonic and geomorphological evolution of forearcs during ridge subduction
Final Report Abstract
In summary, our 3D finite-elements models provided valuable insights into forearc deformation during ridge subduction. Owing to their versatile setup, the models allowed a systematic evaluation of parameters to identify characteristic displacement, strain and stress patterns and to rank the parameters according to the influence. The most influential parameters proved to be the orientation, height and width of the ridge, while the structure and mechanical strength of the forearc as well as the friction coefficient of the plate interface generally do not alter these basic patterns but mostly affect the values of displacement and strain and the size of the areas where maximum values are reached. The application of our models to the natural examples of the Cocos, Nazca and Gagua Ridges yielded important constraints on their subduction history. By coupling a 3D subduction zone model to a landscape evolution model, we could achieve a significant advancement in the modelling technique as such models have never been computed before. The example of the Cocos Ridge model shows that ridge subduction has a great impact on the drainage system of the forearc and that the evolution of the river network provides information on the the ridge subduction history. Provided that the remaining technical problems can be solved, valuable constraints on the subduction histories can be expected from the application of the coupled models to migrating ridges like the Nazca Ridge in the future.
Publications
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(2015), Deformation of erosive and accretive forearcs during subduction of migrating and non-migrating aseismic ridges: Results from 3D finite-element models and application to the Central American, Peruvian and Ryukyu margins. Tectonics 34, 1769-1791
Zeumann, S., A. Hampel
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(2016), Three-dimensional finite-element models on the deformation of forearcs caused by aseismic ridge subduction: The role of ridge shape, friction coefficient of the plate interface and mechanical properties of the forearc. Tectonophysics 684, 76-91
Zeumann, S., A. Hampel
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(2017), Impact of Cocos Ridge subduction on the forearc drainage system. Geology
Zeumann, S., A. Hampel
