The instability of continental passive margins and its effect on continental topography and heat flow - Archive ouverte HAL Access content directly
Journal Articles Journal of Geophysical Research : Solid Earth Year : 2013

The instability of continental passive margins and its effect on continental topography and heat flow

(1) , (1) , ,
1

Abstract

The long geological history of passive margin evolution is complex yet typified by an initial ramp-like tilting of the subaerial surface toward the continent-ocean boundary, followed by episodic uplift and subsidence at a smaller wavelength. We argue that this behavior is due to changes in margin structure brought about by buoyancy-driven lithospheric flow. Continental lithosphere is melt-depleted, buoyant, and thick. It will resist convective breakdown into the asthenosphere below, but will be prone to lateral flow due to horizontal density contrasts. Changes in lithosphere thickness at the transition between continent and ocean will nucleate convection cells. Using a numerical model of viscous upper mantle flow, we show that stability or instability of the continental lithosphere at a passive margin is a function of the lithospheric rheology and composition. Increased compositional buoyancy leads to oceanward lateral flow of the continental lithosphere whereas decreased buoyancy has the opposite effect, causing landward lateral flow of the continental lithosphere. In model simulations, a continental lithosphere thought typical of Phanerozoic continental platforms experiences first a margin-wide ramp-like tilting, followed by topographic fluctuations due to an evolving array of convection cells in the mantle. The timing and magnitude of predicted changes in topography are similar to those observed at the eastern North American margin, suggesting that the tilting and episodic uplift and subsidence at continental passive margins are a natural consequence of the evolution of continental lithosphere after breakup and during mature seafloor spreading.
Fichier principal
Vignette du fichier
JGR Solid Earth - 2013 - Armitage - The instability of continental passive margins and its effect on continental topography.pdf (2.62 Mo) Télécharger le fichier
Origin : Publisher files allowed on an open archive

Dates and versions

insu-03581796 , version 1 (21-02-2022)

Licence

Copyright

Identifiers

Cite

J. J. Armitage, C. Jaupart, L. Fourel, P. A. Allen. The instability of continental passive margins and its effect on continental topography and heat flow. Journal of Geophysical Research : Solid Earth, 2013, 118, pp.1817-1836. ⟨10.1002/jgrb.50097⟩. ⟨insu-03581796⟩
10 View
16 Download

Altmetric

Share

Gmail Facebook Twitter LinkedIn More