31-7 Geology of the Survey Peak 7.5' Quadrangle, Wyoming: Using Detailed Mapping to Reconstruct the Paleo-Topography of the Northern Teton Range and Implications for the Paleo-Teton Collapse Hypothesis

Session: Best Student Geologic Map Competition (Posters)

Presenting Author:

Authors:

Abstract:

The Teton Range is located within the Basin and Range extension province, where N-S striking normal faults, including the range-bounding Teton fault, abruptly terminate at the southern boundary of the eastern Snake River Plain and/or Yellowstone caldera. Traditionally, the active Teton fault is interpreted to terminate at the southern boundary of the ~2.1 Ma Huckleberry Ridge caldera, where the Teton Range topography is essentially absent. Although the present-day fault projection stops at the caldera boundary, recent studies have proposed that the Teton fault once extended farther north and may even be recently active across the modern Yellowstone plateau. If correct, these hypotheses imply that collapse or removal of northern paleo-Teton Range topography may have followed the ~2.1 Ma Huckleberry Ridge caldera eruption.

Here, we integrate new detailed mapping in the Survey Peak 7.5’ quadrangle, recently acquired lidar data, and results from previous geologic mapping to build isopach and structure contour maps and reconstruct the sequential paleo-topography of the Teton Range. This analysis highlights several active or recently active N-S to NW-SE striking normal faults and offset glacial units as young as ~13 ka and may be kinematically linked to the Teton fault. Most of these structures significantly offset the ~2.1 Ma Huckleberry Ridge tuff, indicating that motion is younger than that caldera-forming event. In our analysis, we highlight three recently active structures down to the north normal faults, including: (1) a previously recognized cryptic basement boundary just north of Mount Moran that drops average Teton topography down to the north by ~500 m (and offsets apatite (U-Th)/He isochrons), (2) a normal fault splay linked to the Teton fault that drops the average topography down another 350-400 m, and (3) the Huckleberry Ridge caldera faulted margin, that produces ~800 m of down-to-the-north stratigraphy offset. Combined, these structures lower northern Teton topographic relief by ~1.65-1.70 km, representing ~92-94% of the total relief preserved on the eastern side of the range at Mount Moran (~1.8 km). If correct, these findings raise questions about the mechanisms that drive diminishment of northern Teton topographic relief and also have important implications for the northern Teton fault extension hypothesis.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

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