Testing the importance of sagduction: insights from the Lewisian Gneiss Complex of northwest Scotland
View / Open Files
Authors
Miocevich, SR
Copley, A
Weller, OM
Publication Date
2022Journal Title
Precambrian Research
ISSN
0301-9268
Publisher
Elsevier BV
Type
Article
This Version
VoR
Metadata
Show full item recordCitation
Miocevich, S., Copley, A., & Weller, O. (2022). Testing the importance of sagduction: insights from the Lewisian Gneiss Complex of northwest Scotland. Precambrian Research https://doi.org/10.1016/j.precamres.2022.106708
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 have been invoked to explain these occurrences,
prominent amongst which is the density-driven ‘sagduction’ of high-density upper-crustal lithologies into the underly ing dominantly felsic mid-crust. In this paper we test the geological importance of sagduction, using a combination of
petrology, phase equilibria modelling, and mechanical modelling. We use the Lewisian Gneiss Complex of northwest
Scotland as a test case, analysing the range of observed subordinate felsic–ultramafic bodies within the dominantly
felsic crust, but our approach is applicable to Archean terranes globally owing to their analogous lithological ranges.
We find that for our thermodynamically-estimated densities of the lithologies present in the Lewisian Gneiss Com plex, unrealistically hot temperatures are required for sagduction to be important, given the observed body sizes
and available constraints on event durations, geotherms, crustal rheology and emplacement depths. These results
suggest sagduction is not responsible for emplacement of the 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.
Sponsorship
NERC
Funder references
NERC (via University of Leeds) (RG.EVEA.117755)
NERC (NE/S007164/1)
Identifiers
External DOI: https://doi.org/10.1016/j.precamres.2022.106708
This record's URL: https://www.repository.cam.ac.uk/handle/1810/336783
Statistics
Total file downloads (since January 2020). For more information on metrics see the
IRUS guide.