Journal Article

Thickening Cratonic Lithosphere by Horizontal Compression in the Presence of Surface Erosion and Sedimentation

Pearson, D. Graham, Currie, Claire A., Kublik, Kristina

2025

Overview

Here we examine how lithospheric thickening is affected by active surface sedimentation and erosion in geodynamic models of craton formation—an aspect that has been neglected in previous models even though cratons may be the first landmasses to emerge above sea level. In our two‐dimensional numerical models, inward horizontal velocities are imposed at the side boundaries of the model domain to induce thickening of the cratonic lithosphere by horizontal compression. Various rates of sedimentation and erosion are applied at the surface and the thickness of the lithosphere is monitored during the 50 Myr compression phase, and for 2 billion years after the imposed compression phase. In our models, surface processes act on the high‐relief surface topography of the mobile belts adjacent to the cratonic nucleus. Erosion in the mobile belts during the compression alters lithosphere geodynamics, increasing the thickness of the mobile belt lithosphere to depths capable of supporting diamond growth. This enhanced thickening in the mobile belt regions limits shortening and thickening of the cratonic nucleus and the lithospheric thickness can vary by up to 15 km between models with different surface process rates. Plain Language Summary The single most important event in Earth's history may have been the formation of cratons. These ancient continents have been preserved for billions of years due to their thick lithospheric keels, and they represent the first landmasses to rise above sea level, exposing the surface to erosion. As such, they are the platforms for terrestrial life. The removal and deposition of crustal material from cratons may have provided the impetus for the beginning of life on Earth and may have altered the progression of lithosphere deformation. Despite their significance, surface processes have largely been ignored in geodynamic models of craton formation. We present numerical models that fill this gap in the literature by exploring the effect of surface erosion and sedimentation on lithosphere thickening in a compressional regime. During the compression phase, high rates of erosion decrease thickening in the cratonic nucleus and enhance thickening in the weaker surrounding regions. Although the weaker material is unable to remain thick and stable for billions of years, unlike the cratonic nucleus, the lithosphere in these regions is momentarily in the diamond stability field—a result that does not happen in models with no active surface processes. Key Points Crustal thermal structure is a critical parameter that determines deformational style during lateral craton accretion High surface process rates hinder lithosphere thickening during compressional events, but the long‐term stability of cratons is unaffected Depleted mantle lithosphere is resistant to horizontal compression and fails to adequately thicken to the diamond stability field

• Publisher: John Wiley & Sons, Inc,Wiley
• Subject: Compression / craton formation / cratonic geotherms / Cratons / Diamonds / Erosion rates / Geodynamics / Heat / Lithosphere / lithosphere deformation / Mathematical models / modeling surface topography / neoarchean / Nucleus / Numerical models / Rheology / Sea level / Sedimentation / Sedimentation & deposition / Sedimentation rates / Soil erosion / Tectonophysics / Temperature / Topography