Thesis
MODELING THE STABILITY OF CRATONS CONTAINING PRE-EXISTING WEAKNESSES
Washington State University
Master of Science (MS), Washington State University
01/2021
DOI:
https://doi.org/10.7273/000005448
Handle:
https://hdl.handle.net/2376/119683
Abstract
Cratons are the ancient, typically Archean in age, stable interior of continental plates. They are thicker and more stable than the surrounding lithosphere due to their lithospheric mantle composition of depleted peridotite and limited interaction with convecting mantle. The inherent stability of the cratonic lithosphere should prevent it from undergoing major deformation. However, it has been proposed in some areas, including the Wyoming Craton and the North China Craton, there is evidence that the cratonic lithosphere underwent deformation postdating its assembly, a sign of reactivation. This reactivation could be due to pre-existing weak zones within the cratonic lithosphere, such as suture zones or regions whose composition and rheology were modified by interactions with subducting slabs or mantle plumes. Using Underworld2, we model the stability of cratons with pre-existing weak zones that vary in size, density, and viscosity. This investigation can help us to understand the controls on the stability of cratonic lithosphere with weaker, embedded regions. Our results show that the viscosity of the weak zone plays a strong role the behavior of the craton within the simulations. For example, models with low viscosity weak zones predict delamination and removal of the material. As viscosity of the weak zone increases, the weak material undergoes less deformation. The density and width appear to not influence deformation as much as its viscosity. Other observations within the simulations imply a complex tectonic history for cratons with pre-existing weak zones. For example, in some models, the cratonic lithosphere undergoes extension which could lead to rifting of the craton rifting, particularly in models that have low viscosity weakened areas. These results suggest that reactivated cratons, such as North China Craton and the Wyoming craton, owe their demise to processes that reduce their viscosity rather than those that increase their density.
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Details
- Title
- MODELING THE STABILITY OF CRATONS CONTAINING PRE-EXISTING WEAKNESSES
- Creators
- Shannon Conner
- Contributors
- Catherine Cooper (Advisor)Jeffery Vervoort (Committee Member)Sean Long (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- School of the Environment (CAHNRS)
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Number of pages
- 75
- Identifiers
- 99900592362801842
- Language
- English
- Resource Type
- Thesis