Emplacement age of the Markagunt gravity slide in southwestern Utah, <scp>USA</scp>

Holliday, M.E.; Rivera, Tiffany A.; Jicha, Brian R.; Trayler, Robin B.; Biek, Robert F.; Braunagel, Michael J.; Griffith, W. A.; Hacker, David B.; Malone, David H.; Mayback, Danika F.

doi:10.1111/ter.12630

Cited by 4 publications

(2 citation statements)

References 21 publications

(36 reference statements)

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“…We interpret these features to be frictional melts following the mesoscale criteria defined by Magloughlin and Spray (1992), including a glassy texture with quenched margins at the contact with host rock and the occurrence of vesicles and embayed clasts contained within the glass (Figure 5f). Similar features studied in more detail on the adjacent Markagunt gravity slide also show glassy textures, quenched vein margins, and vesicles and amygdule fillings at the mesoscale, and survivor quartz grains within an isotropic groundmass, flow banding, and microlites in thin section (Biek et al., 2019; Hacker et al., 2014; Holliday et al., 2022; Zamanialavijeh et al., 2021).…”

Section: Discussionmentioning

confidence: 72%

Structural Relationships Across the Sevier Gravity Slide of Southwest Utah and Implications for Catastrophic Translation and Emplacement Processes of Long Runout Landslides

Braunagel

Griffith

Biek

et al. 2023

Geochem Geophys Geosyst

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The physical processes that facilitate long‐distance translation of large‐volume gravity slides remain poorly understood. To better understand these processes and the controls on runout distance, we conducted an outcrop and microstructural characterization of the Sevier gravity slide across the former land surface and summarize findings of four key sites. The Sevier gravity slide is the oldest of three mega‐scale (>1,000 km2) collapse events of the Marysvale volcanic field (Utah, USA). Field observations of intense deformation, clastic dikes, pseudotachylyte, and consistency of kinematic indicators support the interpretation of rapid emplacement during a single event. Furthermore, clastic dikes and characteristics of the slip zone suggest emplacement involved mobilization and pressurized injection of basal material. Across the runout distance, we observe evidence for progressive slip delocalization along the slide base. This manifests as centimeter‐ to decimeter‐thick cataclastic basal zones and abundant clastic dikes in the north and tens of meters thick basal zones characterized by widespread deformation of both slide blocks and underlying rock near the southern distal end of the gravity slide. Superimposed on this transition are variations in basal zone characteristics and slide geometry arising from interactions between slide blocks during dynamic wear and deposition processes and pre‐existing topography of the former land surface. These observations are synthesized into a conceptual model in which the presence of highly pressurized fluids reduced the frictional resistance to sliding during the emplacement of the Sevier gravity slide, and basal zone evolution controlled the effectiveness of dynamic weakening mechanisms across the former land surface.

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Section: Discussionmentioning

confidence: 72%

Structural Relationships Across the Sevier Gravity Slide of Southwest Utah and Implications for Catastrophic Translation and Emplacement Processes of Long Runout Landslides

Braunagel

Griffith

Biek

et al. 2023

Geochem Geophys Geosyst

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“…The timing of this gravity slide, previously estimated between ∼49.5 and 49.7 Ma (e.g., Feeley & Cosca, 2003), has been refined through U‐Pb dating of zircons in the basal layer of the slide to 48.87 ± 0.20 Ma (Malone et al., 2014). The extraordinary size of the Heart Mountain Slide makes it one of the largest terrestrial landslides along with the 23 Ma old Markagunt gravity slide (Hacker et al., 2014; Holliday et al., 2023; Zamanialavijeh et al., 2021).…”

Section: Regional and Local Geologic Settingmentioning

confidence: 99%

High‐Velocity Slip and Thermal Decomposition of Carbonates: Example From the Heart Mountain Slide Ultracataclasites, Wyoming

Zamani,

Heij,

Ferré

et al. 2023

JGR Solid Earth

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The Heart Mountain Slide in Wyoming is one of the largest known terrestrial gravity slides (3,500 km2) formed ∼49 Ma ago by the nearly horizontal detachment of Paleozoic‐Eocene cover sliding on top of autochthonous formations. At the White Mountain locality, exposures offer an exceptional opportunity to investigate high strain rate/high velocity processes in carbonates. Here we use the anisotropy of magnetic susceptibility (AMS) of 274 samples to shed light on ultracataclastic deformation along this detachment. Contrary to predictions, the carbonate ultracataclasite displays a consistent AMS fabric, particularly in the upper ultracataclasite. The AMS in this unit is controlled primarily by magnetite formed through the breakdown of iron sulfides caused by frictional heating. Additional thermomagnetic experiments reveal that the new magnetic fabric began forming ∼250ºC and continued up to ∼400ºC when calcination of carbonate minerals caused a major drop in friction. The main cataclastic slip direction inferred from AMS is ∼N033°, at odds with the previously accepted NNW‐SSE direction. We validate these AMS fabrics through 3D shape preferred orientation analysis and micro X‐ray scanning of the same specimens. These results, however, may only represent cataclastic flow directions at the local scale as a result of synkinematic rotation of the White Mountain block. Alternatively, these results may call for a re‐evaluation of the large scale movement of the slide. Finally, this study demonstrates the usefulness of a magnetic approach in deciphering deformation processes in carbonates, particularly in high strain rate cases such as seismic faults.

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The concept of tectonic provenance: Case study of the gigantic Markagunt gravity slide basal layer

et al. 2022

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Formation and evolution of the basal layer in large landslides has important implications for processes that reduce frictional resistance to sliding. In this report, we show that zircon geochronology and tectonic provenance can be used to investigate the basal layer of the gigantic‐scale Markagunt gravity slide of Utah, USA. Basal layer and clastic injectite samples have unique tectonic chronofacies that identify the rock units that were broken down during emplacement. Our results show that basal material from sites on the former land surface is statistically indistinguishable and formed primarily by the breakdown of upper plate lithologies during sliding. Decapitated injectites have a different tectonic chronofacies than the local basal layer, with more abundant lower plate‐derived zircons. This suggests clastic dikes formed earlier in the translation history from a structurally deeper portion of the slide surface and a compositionally different basal layer before being translated to their current position.

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Emplacement age of the Markagunt gravity slide in southwestern Utah, USA

Cited by 4 publications

References 21 publications

Structural Relationships Across the Sevier Gravity Slide of Southwest Utah and Implications for Catastrophic Translation and Emplacement Processes of Long Runout Landslides

Structural Relationships Across the Sevier Gravity Slide of Southwest Utah and Implications for Catastrophic Translation and Emplacement Processes of Long Runout Landslides

High‐Velocity Slip and Thermal Decomposition of Carbonates: Example From the Heart Mountain Slide Ultracataclasites, Wyoming

The concept of tectonic provenance: Case study of the gigantic Markagunt gravity slide basal layer

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