COMET Webinar: Sophie Miocevich "Testing sagduction: structure & petrology of the Lewisian Gneiss"

Sophie Miocevich (University of Cambridge) presented this webinar on Wednesday 23rd February 2022, with the full title:
"Testing the importance of sagduction: Insights from the structure and petrology of the Lewisian Gneiss Complex, northwest Scotland"

Abstract:
Archean cratons often contain rock units that are interpreted as having been juxtaposed from different structural levels. A range of uniformitarian and non-uniformitarian processes are suggested to explain these occurrences. 'Sagduction' is one such process. Sagduction involves the density-driven 'sagging' of high-density upper-crustal lithologies into the underlying dominantly felsic mid-crust. We integrate petrology, phase equilibria modelling, and mechanical modelling to investigate the geological importance of sagduction, using the Lewisian Gneiss Complex of northwest Scotland as a test case. Our results suggest sagduction is not responsible for emplacement of observed subordinate lithologies within the Lewisian felsic mid-crust, and instead support uniformitarian tectonic interpretations. Additionally, our results cast doubt on the importance of sagduction in the structural evolution of granite-greenstone belts. Overall, our study indicates that sagduction was not an important Archean tectonic process.

This talk was presented as a joint-webinar with Dan Gittins (University of Oxford) and the Q&A portion has been edited to include only questions related to this talk.

If you have questions about Sophie's work, her contact details are here:
  / sophiemiocevich  
https://www.esc.cam.ac.uk/directory/s...