How Slab Age and Width Combine to Dictate the Dynamics and Evolution of Subduction Systems: A 3‐D Spherical Study

Abstract

During subduction, the oceanic lithosphere of one tectonic plate dives beneath another at a convergent margin and is recycled into Earth's mantle (e.g., Kearey et al., 2009;Stern, 2002). As subducted slabs descend, their negative buoyancy provides a key driving force for plate tectonics, and they continue to influence surface processes in a number of ways (e.g.,

The Topographic Signature of Mantle Pressure Build‐Up Beneath Subducting Plates: Insights From Spherical Subduction Models

“…Most notably, the overriding plate (OP) is neglected. This is due to resolution limitations but in line with other time-dependent subduction models within a global domain (Chamolly & Ribe, 2021;Chen et al, 2022;Morra et al, 2009Morra et al, , 2012. Including an OP would reduce the rate of trench retreat relative to SP motion (Butterworth et al, 2012;Yamato et al, 2009) and shift the mantle wedge corner (and hence negative pressure associated with corner flow) to greater depth.…”

“…I use a simplified geometrical, mechanical, and rheological setup and neglect the overriding plate (cf. Chamolly & Ribe, 2021;Chen et al, 2022;Morra et al, 2012). Subduction is initiated by allowing a notch to extend to an initial depth of 150 km with a 250 km radius of curvature (Figure 1).…”

“…I therefore turn to numerical models of subduction to isolate the nature of this sub-SP positive pressure build-up and the resultant DT, in order to assess its global relevance to oceanic topography and hence guide future observational studies. Time-dependent subduction models within a global domain models are relatively rare (Chamolly & Ribe, 2021;Chen et al, 2022;Morra et al, 2009Morra et al, , 2012Quevedo et al, 2013), due to computational challenges, but enable us to incorporate a lower mantle, examine an Earth-like range of plate sizes, and avoid lateral boundary effects. After characterizing the dependence of sub-SP pressure and DT on subduction properties, I search for the modeled topography signal within Holdt et al (2022)'s observationally derived residual depth estimates.…”

Comparing the Dynamics of Free Subduction in Cartesian and Spherical Domains

“…The subducting lithosphere comprises a 2,200 km-long composite plate of constant initial thickness (h = 70 km) with a core isoviscous layer (h c = 30 km) embedded in upper and lower visco-plastic layers with viscosities that follow a von Mises law, consistent with the reference plate in Chen et al (2022). Upper and lower visco-plastic layers approximate the strain-rate weakening that occurs above and below the slab core in thermo-mechanical simulations of subduction (e.g., Garel et al, 2014), following OzBench et al (2008.…”

Overriding plate thickness as a controlling factor for trench retreat rates in narrow subduction zones

“…Previous geodynamic modelling studies have shown the wide variety of physical parameters that influence subduction processes, such as the slab thickness (Bellahsen et al, 2005;Capitanio & Morra, 2012;F. Chen et al, 2022;Funiciello et al, 2008;Stegman et al, 2010) and length (A. F. Holt & Becker, 2016;Xue et al, 2020), the mantle rheology (A. F. Holt & Becker, 2016;Pusok et al, 2018), the strength and thickness of the overriding plate (OP) (Butterworth et al, 2012;Hertgen et al, 2020;A.…”