Numerical modeling of large-scale continental collision
In continental tectonics, questions remain regarding the dominant mechanisms of shortening accommodation during orogen evolution. Two quantitatively-supported models, critical wedge and channel flow, have been applied to the Himalaya and proposed for other large collisional systems. These two models represent fundamentally distinct mechanisms for accommodating shortening in collisional systems and until recently have been viewed as mutually exclusive. While there remains support for these mechanisms being incompatible end-members, in more recent studies it has been proposed that either: (1) both geodynamic mechanisms may operate simultaneously yet in spatially distinct parts of the larger composite orogenic system or (2) both mechanisms are present yet they operate at temporally distinct intervals, wherein the orogen progressively develops through stages dominated by mid-crustal channel flow followed by shallow thrust stacking and duplex development. In both scenarios, the mechanism active at each stage in orogen evolution is presumably dependent upon local to regional scale rheological conditions (as a function of orogen dynamic and thermal evolution) that are likely to be transient in both space and time. However, questions regarding the dynamic, mechanical, and thermal-kinematic relationships of such a system remain. Also, while field observations and deformation records derived from analyses of transects within the Himalaya can be interpreted in such a way to be consistent with a unified model, numerical models that predict the behavior of interactions between the end-member models do not currently exist. Therefore, I use 2-D coupled thermomechanical finite element numerical experiments that examine why current models fail to predict observed fault patterns in some regions. This should provide insights regarding the drivers of deformation in complex collisional systems.
Coupling tectonics with surface processes
Theoretical and numerical geodynamic models of continental collisional systems often involve, either explicitly or implicitly, a necessary yet complicated dependence between tectonics and erosion; however, the exact nature of these relationships remains elusive and controversial. In such models for the Himalayan-Tibetan (HT) collisional orogen, surface processes are theorized or in some cases required to play an essential role in modulating critical processes active in the evolution of that system. To investigate, at least to first order. these interactions between climate and tectonics, I generated a simplified landscape evolution model of an actively uplifting orogenic wedge acted upon by surface processes for my MS work. I varied parameters in the equations governing landscape evolution and made observations of the topographic evolution response in the active orogen. I used comparisons with the topography of the modern HT system, along with measured thrust, uplift and erosion rates, to establish erodibility parameter (K) values consistent with observations from the modern HT orogenic system. These values were then used to assess the viability of uplift and erodibility conditions required in current HT geodynamic models, including crustal channel flow.
For more information, visit my ResearchGate page. |
Sparks, Stephanie Ann, "Influence of Bedrock Erodibility on Orogen Evolution in Collisional Systems and Implications for Geodynamic Models" (2022). Theses and Dissertations--Earth and Environmental Sciences. 93. https://uknowledge.uky.edu/ees_etds/93
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