Constraining the Range and Variation of Lithospheric Net Rotation Using Geodynamic Modeling

Abstract

Quantifying the net rotation of the Earth's lithosphere remains an unsolved problem in geodynamics and plate tectonic reconstructions. Net rotation is the movement of the entire lithosphere as a solid body with respect to the Earth's mantle. It is therefore one component of the motion recorded with respect to the Earth's magnetic dipole, preserved in the palaeomagnetism of rocks. However, three other components of motion are also preserved in the palaeomagnetism (Jurdy, 1981): movement of individual plates (continental drift); rigid-body rotation of the lithosphere and mantle with respect to the Earth's spin axis (true polar wander; Duncan & Richards, 1991;Steinberger & Torsvik, 2008); and movement of the Earth's magnetic dipole relative to the Earth's spin axis. The contribution of these processes to palaeomagnetic data cannot be separated. In order to study any one of these components, for example when building absolute plate motion models, assumptions for the others must be made in order to reconstruct the movement of the lithosphere through geological history (Coltice et al., 2017;Tetley et al., 2019).The lithospheric net rotation (LNR) estimates require a stable reference point in the mantle. Mantle plumes and hotspots are generally used, as these are considered to have been roughly stable for the last few tens of millions of years (

Generation of evolving plate boundaries and toroidal flow from visco-plastic damage-rheology mantle convection and continents

“…11, reaches NR values that are comparable to that inherent in the M üller et al ( 2016) plate model. This effect is expected given the role of continental vs. oceanic asthenospheric viscosity variations (Ricard et al, 1991;Zhong, 2001;Becker, 2006;Rudolph & Zhong, 2014), and the amplitudes broadly consistent with those expected from 2-D cylindrical computations (Gérault et al, 2012;Atkins & Coltice, 2021).…”

“…Submitted to G-Cubed, August 2023 manuscript submitted to Geochemistry, Geophysics, Geosystems evolving convection models indicate that moderate values, e.g. of Fig.1awith TPR( = 1) 80%, might be typical(Atkins & Coltice, 2021). The time-averaged TPR( = 1) fromSeton et al (2012) and are ≈56% and ≈26%, respectively, from the median spectra of the last 140 Ma.…”

Generation of Evolving Plate Boundaries and Toroidal Flow From Visco‐Plastic Damage‐Rheology Mantle Convection and Continents

“…18 of 27 oceanic asthenospheric viscosity variations (Becker, 2006;Ricard et al, 1991;Rudolph & Zhong, 2014;Zhong, 2001), and the amplitudes are broadly consistent with those expected from 2-D cylindrical computations (Atkins & Coltice, 2021;Gérault et al, 2012).…”

“…Temporal fluctuations in the power spectra are particularly large for the ℓ = 1, NR terms (Rudolph & Zhong, 2014) and the geophysical and geological constraints are compatible with a range of NR values (Tetley et al., 2019). However, time‐evolving convection models indicate that moderate values, for example, of Figure 1a with TPR( ℓ = 1) ≲ 80%, might be typical (Atkins & Coltice, 2021). The time‐averaged TPR( ℓ = 1) from Seton et al.…”