Flexural Modeling of Foreland Basins

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Abstract/Contents

Abstract
This contribution focuses on the e↵ect of laterally varying elastic thickness in the un- derlying lithosphere and thrust loading on foreland basin subsidence. I use numerical models to compare flexural subsidence patterns expected in basins with little lateral variation in crustal thickness (e.g., Chaco Basin in Bolivia) with those typical of strong lateral variations in this property (Magallanes-Austral Basin in Chile/Argentina). In the Chaco Basin case, the observed basin geometry is well modeled using an elastic beam with uniform rigidity. In contrast, the Magallanes-Austral Basin contains rem- nants of the Rocas Verdes backarc basin proximal to the Patagonian fold-and-thrust belt and transitions to unattenuated continental crust in the distal plate segment from the thrust front. As a result of this strong lateral variation in crustal thickness, flexural subsidence predicted by an uniform-rigidity elastic beam model is inconsis- tent with measured subsidence. Instead, a model with varying elastic thickness better reconciles the bathyal foredeep and the relatively long wavelength deflection observed in the Magallanes-Austral case. I further this analysis with non-dimensionalizing the varying rigidity model and explore the evolution of basin geometry as the thrust front horizontally expands. I find that the initial phases of basin development are flexurally driven, but as the topographic load expands horizontally, isostatic forces take over and the basin depth becomes dependent on the crustal loading configurations rather than on the properties of the underlying lithosphere. The modeled basin history also has implications for sediment patterns, as rigidity variations in the lithosphere can result in hinge-like subsidence that localizes deposition spatially instead of relative to the thrust front.

Description

Type of resource text
Date created March 16, 2018

Creators/Contributors

Author Liu, Yuchen
Primary advisor Hilley, George
Advisor Malkowski, Matthew
Degree granting institution Stanford University, Department of Geological Sciences

Subjects

Subject Geological Sciences
Subject Stanford Tectonic Geomorphology Lab (STGL)
Subject Stanford University
Subject Earth Energy & Environmental Sciences
Genre Thesis

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This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).

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Preferred Citation
Liu, Yuchen. (2018). Flexural Modeling of Foreland Basins. Stanford Digital Repository. Available at: https://purl.stanford.edu/qz945ks9541

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Master's Theses, Doerr School of Sustainability

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