Postglacial slip distribution along the Teton normal fault (Wyoming, USA), derived from tectonically offset geomorphological features

Abstract

Along the eastern front of the Teton Range, northeastern Basin and Range province (Wyoming, USA), 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). Here we use 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. 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 fault 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 three-dimensional numerical models, 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.

Quantifying rates of Quaternary landscape evolution in Grand Teton National Park using in situ cosmogenic 10Be, 14C, and 36Cl dating

“…One of these features (the 'String Lake' debris flow) is offset by the Teton Fault. Recent work suggests the magnitude of vertical fault slip on the String Lake debris flow is 25.3 ± 2.5 m (Hampel et al, 2021). Similar to our approach at Fan 1, 10 Be ages from the String Lake debris flow will constrain the time 2021) estimate of vertical Teton Fault slip at this location, we will be able to determine time-integrated Teton Fault slip rate.…”

“…Total stratigraphic offset along the Teton fault far exceeds present topographic relief (∼2 km) and is estimated to be 6-9 km since its inception between 13 and 5 Ma (Smith et al, 1993). Well-preserved fault scarps displacing Pinedale-age glacial moraines (Licciardi and Pierce, 2008;Pierce et al, 2018) and disturbed sediment layers in fault trenches (Byrd et al, 1994;Zellman et al, 2020) (Pierce and Haller, 2011), but recent work suggests that slip rates may have been both temporally-and spatially-variable (e.g., Thackray and Staley, 2017;DuRoss et al, 2020;Hampel et al, 2021). A paleoseismic record from Jenny Lake sediments confirms these inferences, indicating that large-magnitude seismic events occurred more frequently immediately following regional deglaciation at ∼15 ka (Larsen et al, 2019).…”

“…By combining the 10 Be ages with published estimates of fault offset and/or slip from LiDAR (Thackray and Staley, 2017;Hampel et al, 2021), we will be able to generate centennial-scale reconstructions of cumulative fault motion at multiple locations.…”

Sedimentological characterization of earthquake-generated turbidites in fault-proximal glacial lakes: a case study from Jenny Lake, Teton range, Wyoming

“…Fault displacement during the past approximately 15,000 years is recorded by prominent fault scarps that displace glacier deposits from the most recent (Pinedale) glaciation (Figure 1; Pierce et al, 2018;Licciardi and Pierce, 2018;Zellman et al, 2019). In general, vertical surface offsets of glacial and colluvial landforms are greatest in the central portion of the fault, where they exceed 25 m in the region near Jenny Lake and decrease to approximately 10 m toward the northern and southern ends (Hampel et al, 2021). Based on these surface offsets and the attendant landform ages, relatively high time-averaged postglacial slip rates of approximately 1.8 mm/yr and approximately 0.9 mm/yr have been inferred for the central and distal portions of the fault, respectively (Thackray and Staley, 2017;Hampel et al, 2021).…”