GSA Connects 2022 meeting in Denver, Colorado

Paper No. 172-4
Presentation Time: 9:00 AM-1:00 PM


HAMPEL, Andrea, Leibniz Universitaet Hannover, Institut fuer Geologie, Callinstr. 30, Hannover, 30167, GERMANY and HETZEL, Ralf, Westfälische Wilhelms-Universität Münster, Institut für Geologie und Paläontologie, Corrensstr. 24, Münster, 48149, Germany

Along the eastern front of the Teton Range, Wyoming, well-preserved fault scarps that formed across moraines, river terraces and other geomorphological features indicate that multiple earthquakes ruptured the range-bounding Teton normal fault after the Last Glacial Maximum (LGM). In our study, we used high-resolution digital elevation models derived from Lidar data to determine the vertical slip distribution along-strike of the Teton fault from 54 topographic profiles across tectonically offset geomorphological features along the entire Teton Range front (Hampel et al., Geosphere, 2021). We find that offset LGM moraines and glacially striated surfaces show higher vertical displacements than younger fluvial terraces, which formed at valley exits upstream of LGM terminal moraines. Our results reveal that the tectonic offsets preserved in the faults scarps are post-LGM in age and that the postglacial slip distribution along-strike of the Teton fault is asymmetric with respect to the Teton Range center, with the maximum vertical displacements (27-23 m) being located north of Jenny Lake and along the southwestern shore of Jackson Lake. As indicated by earlier 3D numerical models (Hampel et al., 2007), this asymmetric slip distribution results from postglacial unloading of the Teton fault, which experienced loading by the Yellowstone ice cap and valley glaciers in the Teton Range during the last glaciation. In the future, we will use the new constraints on the postglacial paleo-earthquake history of the Teton fault from Jenny Lake sediment cores (Larsen et al. 2019) and the Buffalo Bull trench site (DuRoss et al., 2019) as well as updated 10Be exposure ages on the deglaciation history of the Yellowstone ice cap (Larsen et al., 2016; Licciardi and Pierce, 2018) to investigate the postglacial response of the Teton fault to deglaciation of the Teton-Yellowstone region with an updated numerical model including earthquake cycles.