8898 Seminar Earth Sciences
Speakers: Datu Adiatma and Michael Braunagel
Seminar Titles: Tracking changes in silicate weathering during the Ordovician using Lithium isotopes stratigraphy and Emplacement of the Sevier Gravity Slide by Thermal Pressurization of Basal Shear Zone Fluids
Description:
Silicate weathering is an important control of Earth’s climate over multi-million-year timescales. Geologic processes such as mountain uplift can induce global cooling by increasing rates of physical and chemical weathering of silicate rocks that consume CO2 from the atmosphere. In this seminar, I will present one of my dissertation projects that focuses on constraining changes in the global silicate weathering during the Ordovician Period (~486 – 443 Ma) using lithium isotope stratigraphy.
The Sevier gravity slide records the first of three mega-scale (> 1000 km2) gravitational collapse events of the southern Marysvale volcanic field of southwestern Utah during late-stage volcanic activity in the region. The mechanics permitting 30 km of translation across the former land surface during emplacement of this structure and other similar long-runout landslides remain poorly understood. To better understand these phenomena and the controls on runout distance, we conduct a photogrammetry-based outcrop-scale along a transport-parallel transect. Field observations including intense deformation, clastic injectites, pseudotachylyte, and consistency in kinematic indicators support the interpretation that emplacement of the Sevier gravity slide occurred with high velocities and during a single event. Furthermore, clastic injectites and characteristics of the slip zone indicate the basal material underlying the slide behaved as a highly pressurized fluid during emplacement. Over this extensive runout distance, heterogeneities including varying lithologies, pre-existing topography and asperities, and an evolving damage state due to wear and mechanical breakdown of the upper plate greatly impact the physical processes controlling basal fluid pressures.
Host: Steven Lower
Zoom Meeting information
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