RECONSTRUCTING THE PALEOZOIC-MIOCENE PALEO-TOPOGRAPHY OF THE NORTHERN TETON RANGE WITH IMPLICATIONS FOR THE PALEO-TETON COLLAPSE HYPOTHESIS: NEW INSIGHTS FROM DETAILED GEOLOGIC MAPPING OF THE SURVEY PEAK 7.5’ QUADRANGLE

The Teton Range lies at the convergence of the Basin and Range, the Yellowstone caldera, the Sevier fold-and-thrust belt, and the Laramide Gros Ventre-Wind River basement uplifts. The intersection of these structural and tectonic provinces has historically complicated the interpretations for the geological history of the Teton Range, particularly regarding the onset timing and magnitude of uplift. The ~70 km-long Teton Range is driven by active footwall uplift on the Teton fault which has its northern terminus truncated abruptly by the Huckleberry Ridge (~2.1 Ma) caldera, which also marks the southern boundary of the low-relief track of the Yellowstone hotspot. Recent studies have proposed that the Teton fault once extended much further north than the present-day expression of the range and may remain active across the modern Yellowstone caldera. In that scenario, the northern paleo-Teton Range must have collapsed into the Huckleberry Ridge caldera following the supercaldera eruption at ~2.1 Ma. However, the potential structural architecture and kinematics of this collapse scenario remains mostly unknown. In the Survey Peak 7.5’ quadrangle of the northern Tetons, new detailed mapping integrated with previous mapping and lidar data reveals active N-S striking normal fault scarps that significantly offset rhyolites as young as ~850 ka. In the study area, Paleoproterozoic basement is unconformably overlain by Paleozoic-Mesozoic sedimentary units that are deformed by the Forellen Peak fault. These units are overlain by several generations of Tertiary and Quaternary volcanic and volcaniclastic units. The extensive displacement of normal faults that offset the 2.1 Ma Huckleberry Ridge tuff indicates significant recent (<2 Ma) extension within the mapping area. Furthermore, the normal faults generated significant landslide complexes along the western and eastern edges of the mapping area. Structural analysis, including new cross-sections and structure contour maps, allows reconstruction of paleo-topography and provides insight into the landscape evolution of the northern Teton Range. These analyses also provide new constraints for the collapse and removal of paleo-Teton topography near the caldera boundary.