Master of Science
Earth and Environmental Sciences
Frank J. Pazzaglia
Cyclical lithostratigraphy in terrestrial Pleistocene sedimentary deposits is traditionally interpreted as the result of exogenic interglacial-glacial cycles, accommodated by basin subsidence. Recent challenges to this model propose that signals generated by autogenic processes inherent to hillslope, fluvial, and marine systems can obscure exogenic signals in the sedimentological record. This study constructs a high-resolution age model for a continuous exposure of middle Pleistocene fluvial sedimentary cycles at the edge of an actively subsiding foreland basin, ties that model to the global benthic δ18O stack, and uses it to test the canonical climate-driven sedimentation model for terrestrial Pleistocene sedimentary cycles against competing tectonic- and autogenic process-modulated sedimentation models. The age model is verified using palynology and paleosol characterization as independent climate proxies, as well as TCN burial ages and paleo-erosion rates. Results indicate that sedimentary cycles in the study section are best explained by periodic autogenic delta processes in an accommodation space-limited system. These findings are a powerful addition to the ongoing debate over whether signals generated by large scale, exogenic forcing can survive transport to be preserved in the sedimentary record and help define the temporal and spatial scales at which they operate.
Gelwick, Katrina Desiree, "Decoupled lithostratigraphy, orbitally-driven climate, and tectonics for a middle Pleistocene stratigraphic section" (2019). Theses and Dissertations. 5657.
Available for download on Friday, February 26, 2021