How craton margins are preserved: Insights from geodynamic models

Abstract

 lateral changes in continental lithosphere thickness induce edge-driven convection  thick cratonic lithosphere is readily eroded if it is weak due to partial hydration  steep cratonic margins are preserved for at least 100 Ma if the lithosphere is dry  moderate compositional buoyancy enhances margin stability

Lithospheric modification by extension and magmatism at the craton-orogenic boundary: North Tanzania Divergence, East Africa

“…Vauchez et al 2005). This is consistent with progressive lateral erosion over time (Sleep et al 2002;Currie & van Wijk 2016). Local lateral changes in composition may also help to preserve cratonic roots and control the mantle upwelling extension towards the surface.…”

“…Yet in the MNM rift zone, the role of a thick cratonic lithosphere overlying Archaean mantle in the localization of the strain and the magmatism distribution remains an outstanding question (e.g. King & Ritsema 2000;Priestley et al 2008;Albaric et al 2014;Currie & van Wijk 2016). Based on thermal modelling (Priestley & McKenzie 2006) and shear wave tomographic models (Fishwick 2010), the lithospheric thickness variation has been estimated beneath African continent at a regional scale and clearly shows a thinning beneath the Eastern rift in Tanzania (Priestley et al 2008;Fishwick 2010).…”

“…Asthenospheric upwelling may be reinforced by small-scale convection caused by compositional variations and lithospheric step between cratonic edges and neighbouring units (van Wijk et al 2008). To maintain the craton root stability, though, its hydration should track only modern metasomatism and cratonic root removal (Currie & van Wijk 2016). The small Tanzanian Craton is thinner than the Kaapvaal and Congo Cratons, and kimberlite compositions show progressive thinning and hydration (e.g.…”

Lithospheric Structure of a Transitional Magmatic to Amagmatic Continental Rift System—Insights from Magnetotelluric and Local Tomography Studies in the North Tanzanian Divergence, East African Rift

“…Finally, we challenge the generally accepted concept about the influence of inherited structures as "cratonic features acting as a barrier to rift propagation and magmatism" [94]. The presence of a conductive body (C 5 ) beneath Mbulu domain may be the evidence for the propagation of the Eyasi branch throughout the Tanzanian Craton.…”

Global distribution of sediment-hosted metals controlled by craton edge stability

“…Regardless of age, sediment-hosted base-metal deposits predominantly cluster on the edges of present-day thick lithosphere. Therefore, many of these lithospheric steps appear to be remarkably robust on billion-year timescales, despite the assembly and disaggregation of several supercontinents, the impacts of large igneous provinces and the possible erosional effect of edge-driven convection (Currie & van Wijk, 2016). Deposit ages in northwestern North America span ∼1.5-0.5 Ga, pointing to the stability and importance of this boundary in localising multiple deformational and oreforming processes.…”