Numerical investigation of deep-crust behavior under lithospheric extension

Megan Korchinski, Patrice F. Rey, Luke Mondy, Christian Teyssier, Donna L. Whitney

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

What are the conditions under which lithospheric extension drives exhumation of the deep orogenic crust during the formation of gneiss domes? The mechanical link between extension of shallow crust and flow of deep crust is investigated using two-dimensional numerical experiments of lithospheric extension in which the crust is 60 km thick and the deep-crust viscosity and density parameter space is explored. Results indicate that the style of extension of the shallow crust and the path, magnitude, and rate of flow of deep crust are dynamically linked through the deep-crust viscosity, with density playing an important role in experiments with a high-viscosity deep crust. Three main groups of domes are defined based on their mechanisms of exhumation across the viscosity-density parameter space. In the first group (low-viscosity, low-density deep crust), domes develop by lateral and upward flow of the deep crust at km m.y−1 velocity rates (i.e. rate of experiment boundary extension). In this case, extension in the shallow crust is localized on a single interface, and the deep crust traverses the entire thickness of the crust to the Earth's near-surface in 5 m.y. This high exhuming power relies on the dynamic feedback between the flow of deep crust and the localization of extension in the shallow crust. The second group (intermediate-viscosity, low-density deep crust) has less exhuming power because the stronger deep crust flows less readily and instead accommodates more uniform extension, which imparts distributed extension to the shallow crust. The third group represents the upper limits of viscosity and density for the deep crust; in this case the low buoyancy of the deep crust results in localized thinning of the crust with large upward motion of the Moho and lithosphere-asthenosphere boundary. These numerical experiments test the exhuming power of the deep crust in the formation of extensional gneiss domes.

Original languageEnglish (US)
Pages (from-to)137-146
Number of pages10
JournalTectonophysics
Volume726
DOIs
StatePublished - Feb 15 2018

Bibliographical note

Funding Information:
The authors would like to thank an anonymous reviewer for their helpful suggestions and comments, which greatly improved the manuscript. We acknowledge John Mansour at Monash University, Australia, for generously donating his time and effort troubleshooting during Underworld installation. We also acknowledge the Minnesota Supercomputing Institute for help with software installation and management; in particular we thank Brent Schwartz, Besitie Wang, Andrew Gustafson, and Nancy Rowe for their help and advice. This research was supported by National Science Foundation (grant EAR-1050020 ), the Australian Research Council 's ITRH Project (grant IH130200012 ), and the Geological Society of America ( 11113-15 ) and the Department of Earth Sciences, University of Minnesota . Underworld is open-source software provided by AuScope Ltd. and funded under the National Collaborative Research Infrastructure Strategy, an Australian Commonwealth Government Programme.

Funding Information:
The authors would like to thank an anonymous reviewer for their helpful suggestions and comments, which greatly improved the manuscript. We acknowledge John Mansour at Monash University, Australia, for generously donating his time and effort troubleshooting during Underworld installation. We also acknowledge the Minnesota Supercomputing Institute for help with software installation and management; in particular we thank Brent Schwartz, Besitie Wang, Andrew Gustafson, and Nancy Rowe for their help and advice. This research was supported by National Science Foundation (grant EAR-1050020), the Australian Research Council's ITRH Project (grant IH130200012), and the Geological Society of America (11113-15) and the Department of Earth Sciences, University of Minnesota. Underworld is open-source software provided by AuScope Ltd. and funded under the National Collaborative Research Infrastructure Strategy, an Australian Commonwealth Government Programme.

Publisher Copyright:
© 2018 Elsevier B.V.

Copyright:
Copyright 2018 Elsevier B.V., All rights reserved.

Keywords

  • Exhumation
  • Extension
  • Gneiss domes
  • Numerical modeling
  • Rheology

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