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Terra Nova


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.

Funding Source

Funding for this research was provided by the National Science Foundation (EAR2113158), the Utah Geological Survey, the Illinois State University Foundation, the Kent State University Research Council and the Geological Society of America through sponsorship of a Thompson Field Forum.



This article was originally published in Terra Nova, vol. 34, issue 5, October 2022;

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

ter12608-sup-0002-appendixs2.docx (21 kB)
supplemental data

ter12608-sup-0001-appendixs1.xlsx (1020 kB)
supplemental data

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