284 D33. Recent Advances in Tectonics/Tectonophysics (Posters)

Wednesday, 25 September 2019
9:00 AM - 6:30 PM
Hall AB, North Building

UTILIZING APATITE (U-TH)/HE ANALYSES, LANDSCAPE AND KINEMATIC MODELING TO EXAMINE THE RELATIVE EFFICACY OF CLIMATIC AND TECTONIC FORCING IN AN ACTIVE TECTONIC SYSTEM: TETON RANGE, WY

Paper number: 284-3
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

Abstract

Understanding the relative importance of tectonic (uplift) v. climatic (precipitation) controls governing landscape response in active tectonic systems remains as a fundamental challenge in orogenic studies. Some studies have proposed that climatic variables can fundamentally influence the tectonic response, whereas other studies have demonstrated that uplift rate and magnitude is the first-order control on denudation and climate. Additionally, several studies have suggested that the mechanism by which erosion occurs is critical (i.e. glacial v. fluvial), whereas others have proposed that both mechanisms can denude landscapes fast enough to keep up with tectonic uplift. Recent work by our group in the Teton Range, WY, combined apatite (U-Th)/He (AHe) thermochronology, landscape analysis, and seismic reflection imaging of glacial lakes to investigate temporal and mechanistic controls on short- to long-term denudation. In that work, long-term canyon incision rates of 0.24 mm yr-1 were determined using AHe thermochronology for major drainages near Mount Moran, which corresponds with the highest uplift rates and greatest uplift duration during growth of the Teton Range. Sediment volumes derived from fluvial deposits in Moran Bay were used to calculate short term denudation rates of 0.00303-0.4672 mm yr-1 during the most recent glacial interval. In a related study we found that high talus production rates of 1.13-1.14 mm yr-1 are possible and suggest that the Teton Range is transport limited during interglacial periods, as the fluvial transport system is largely unable to move large volumes of canyon sediment in this relatively small-scale system. In future work, we will integrate additional low-T thermochronology analyses with kinematic modeling (2D Move), thermal-kinematic modeling (PECUBE), and landscape evolution models (Cascade/IceCascade) to assess the conclusions that: (1) Rock uplift is the fundamental control on long-term incision rates, and (2) Glaciers, not fluvial systems, dominantly control erosion rate. When properly integrated, these models will allow us to simulate various sediment transport scenarios, both fluvial and glacial erosion, to estimate erosional history over time and elucidate the first order driver of incision as displacement and deformation occur along the normal fault.

Geological Society of America Abstracts with Programs. Vol. 51, No. 5

doi: 10.1130/abs/2019AM-338520

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