Stratigraphic response to Cordilleran processes along the south central Andean margin


Subduction zones along convergent plate margins are fundamental components of Earth systems that link mountain building, magmatism, lithospheric dynamics, surface processes, and climate-carbon cycles. Resolving the feedbacks and relationships among these components has been a longstanding challenge in Earth science with broad implications for understanding coupling among rheology, deformation, and erodibility. The sedimentary record within convergent systems provide a unique opportunity to understand long-lived Cordilleran processes between subduction, magmatism, erosion, sediment routing, and deposition. This dissertation investigates the Phanerozoic to present sedimentary record to address the dynamic interactions among Earth-surface processes and lithospheric processes throughout a complex tectonic history along the Andean Cordilleran margin of Argentina.

Chapter 1 applies detrital zircon U-Th-Pb and Lu-Hf isotopic datasets as a powerful methods for evaluating long-term, regional geologic patterns and the processes of crustal addition, removal, and recycling to help resolve the onset of Andean subduction, and the relationships and feedbacks among upper-and lower-plate processes, and the timescales of Cordilleran evolution. A large Phanerozoic compilation of new and published zircon data provides new insights into how changes in the subducted lower-plate are fundamental drivers to magmatism composition, spatial patterns, and deformation. This chapter will be submitted to Geological Society of America Bulletin with coauthors Ryan McKenzie, Brian Horton, Chelsea Mackaman-Lofland, and Daniel Stockli.

Chapter 2 integrates field measurements with a large detrital geochronology datasets to establish a lithostratigraphic and chronostratigraphic record of Neogene Andean flat-slab subduction. Coeval cycles of upward coarsening stratigraphic trends, erosional unroofing, deformation, and magmatic high flux events provides new evidence of upper-plate Cordilleran feedbacks driven by changes in subduction regime. This chapter will be submitted to Lithosphere with coauthors Brian Horton, Chelsea Mackaman-Lofland, Ryan McKenzie, Daniel Stockli, Gustavo Ortiz, and Patricia Alvarado.

Chapter 3 uses detrital zircon from modern river sands to understand how landscapes respond to variation in bedrock erosion, structural setting, drainage network, and transport processes. This chapter provides new tools and geologic understandings to arm future researchers attempting to studying sedimentary provenance in convergent margins settings. This chapter was published in Earth and Planetary Science Letters in December, 2017 with coauthors Brian Horton, Ryan McKenzie, Daniel Stockli, and Margo Odlum.