Congratulations to Alex Tye who defended his dissertation on Monday, October 21, 2019
Advisor: Nathan Niemi
Deformation within continents is typically not confined to plate margins, but is distributed throughout a variety of discrete and diffuse structural systems within continental interiors. The distribution of strain within continents is the subject of much active research because it is of primary importance in determining Earth’s topography, the distribution of Earth resources, and hazards. This dissertation consists of two strands that advance the study of how strain is distributed in continental lithosphere. The first strand (Chapters 2-5) presents several novel statistical tools for quantifying the effects of continental deformation. The second strand (Chapters 6, 7) uses a natural example, the Greater Caucasus orogen, to investigate the inception of continental collision, which drives Earth’s most dramatic continental deformation.
The dissertation consists of a total of eight chapters. Chapter 1 motivates the study of continental deformation and the use of rigorous statistical methods in Earth science. Chapter 2 presents a novel Bayesian method for comparing detrital zircon U-Pb age datasets that enhances the use of such datasets to trace sediment transport and unravel the stratigraphic records of continental tectonic systems. Chapter 3 applies the new Bayesian method to several previously published detrital zircon U-Pb age datasets, demonstrating its utility in quantifying sedimentary processes. Chapters 4 and 5 develop a new source of paleoseismic slip histories within zones of continental extension, the statistics of rock strength and surface roughness on bedrock normal fault scarps. Chapter 6 uses a comprehensive, new detrital zircon U-Pb age dataset to characterize the exhumational and sedimentary response of an orogen and its foreland basin to the initiation of continental collision, providing a new set of criteria for recognizing the onset of collision in older collisional orogens globally. Chapter 7 characterizes deformation and exhumation within the active accretionary prism of the eastern Greater Caucasus, augmenting our understanding of how strain is accommodated within these tectonic systems, which are ubiquitous at convergent plate boundaries. Chapter 8 concludes by summarizing the contributions of the dissertation.
The dissertation develops new statistical techniques for quantifying the effects of continental deformation and reports new findings from the Greater Caucasus that enhance our understanding of the evolution of convergent to collisional tectonic systems and their sedimentary records. These contributions provide new insight into how strain is distributed in continents and may serve to guide future investigation in this research area.