A Modified Global Plate Model Including Quantitative Tomotectonic Plate Reconstruction of Western North America and the Eastern Pacific Basin

This plate model is based on that of Clennett et al. (2020) (https://zenodo.org/records/10348271). The Clennett et al. (2020) model was an extension of the global model of Müller et al. (2019) (https://zenodo.org/records/10525287), with a focus on producing a more detailed tectonic reconstruction of the North American Cordillera. Further minor modifications were made to the model for a paper by Alfonso et al. (2024), using the GPlates software (https://www.gplates.org/). Firstly, several subduction zones in the published plate model have no associated motions, instead remaining entirely stationary relative to the mantle. This was judged to be incompatible with basic geodynamic principles, as geodynamic models indicate that trenches and subducting slabs are almost always in motion relative to the mantle, exhibiting retreat or, more rarely, advance (e.g. Capitanio, 2013; Capitanio et al., 2010; Schellart et al., 2007; Stegman et al., 2010). As trenches of intermediate length generally display relatively slow retreat (Schellart, 2008), a small amount of trench rollback was imposed on the subduction zones in this model, whilst ensuring that they remained located above their associated tomographically-imaged slabs. Additionally, the Orcas plate (170–130 Ma), located within the Cordilleran archipelago, was split into two sections separated by an east-west trending mid-ocean ridge, consistent with the subsequent plate configuration after 130 Ma. This was done to improve the consistency of the plate motion model, which appeared to indicate divergence within the Orcas plate and convergence at its boundaries. Finally, the reconstruction’s absolute plate motion model was recalculated using the iterative optimisation workflow developed by Tetley et al. (2019). The agegrids associated with this model can be accessed from: https://repo.gplates.org/webdav/PlateModel_Age_SR_Grids/Alfonso_etal_2024_modClennettMuller/