Imaging, mapping and modelling continental lithosphere extension and breakup: an introduction

Abstract

AbstactThis Special Publication is a direct outcome of a small but dedicated group of researchers who met in Pontresina, Switzerland, to review and define the fundamental observations characterizing extensional systems and their application in guiding and constraining modelling efforts and results. The various summaries of the keynote addresses give an objective overview of the state of the art in modelling lithospheric extensional systems, both from the regional scale using dynamic models to individual basins using kinematic models with an emphasis on capturing the extensional history of the Iberia and Newfoundland margins. At the heart of all of these efforts is a simple question: Exactly what mechanisms allow the continental lithosphere to be thinned to the point of rupture? Related questions are: (1) Do crustal and mantle faults play a major role in this thinning process? If so, what is their geometry and does their importance and geometry change with time? (2) Are there other mechanisms of lithospheric and crustal thinning that cannot be imaged on seismic sections? (3) How is deformation accommodated in space and time? (4) What role do inherited mechanical, thermal and/or chemical heterogeneities play in controlling strain distribution and localization? (5) When, how and to what degree does magma production affect the distribution and localization of extension? And (6) what is the stratigraphic record of continental extension and how does it document the extension of the crust and thinning of the lithospheric mantle?The aim of this Special Publication is to address many of these fundamental questions concerning the extreme extension and thinning of continental lithosphere.

Conjugate rifted margins width and asymmetry: The interplay between lithospheric strength and thermomechanical processes

“…Continental extension is a key result of plate tectonics and leads to rifting and the formation of many of the world's passive margins and ocean basins. Globally rifted margins exhibit a remarkable variation in structural style, including in the width of the domain of thinned continental crust, the degree of asymmetry of conjugate margins, and the amount, type, and spatial and temporal evolution of their sedimentary and magmatic sections [Sengör and Burke, 1978;Royden and Keen, 1980;Steckler et al, 1998;Eldholm et al, 2000;Boillot and Froitzheim, 2001;Davis and Kusznir, 2004;Manatschal, 2004;Geoffroy, 2005;Karner et al, 2007;Van Avendonk et al, 2009;Péron-Pinvidic and Manatschal, 2009]. This range in the style of rifted margins is largely the mechanical consequence of the variability in crustal thickness, lithospheric thermal structure, rheological properties of the crust and mantle, finite strain, and extension rates [England, 1983;Kusznir and Park, 1987;Bassi, 1991Bassi, , 1995Buck, 1991;Buck et al, 1999;Huismans et al, 2005;Lavier and Manatschal, 2006;Gueydan et al, 2008;Huismans and Beaumont, 2011;Brune et al, 2014].…”

Dominant symmetry of a conjugate southern Australian and East Antarctic magma-poor rifted margin segment

“…The mechanisms of rifting of continental lithosphere to the point of rupture and seafloor spreading remain some of the more poorly understood aspects of the plate tectonic paradigm [e.g., Karner et al , 2007; Péron‐Pinvidic et al , 2009]. A major impediment has been the limited number of conjugate margin pairs on which high‐quality data are available to allow the empirical testing of numerical models of breakup mechanisms [e.g., Huismans and Beaumont , 2002, 2003; Nagel and Buck , 2004].…”

Influences on the development of volcanic and magma-poor morphologies during passive continental rifting

“…A number of possible controls have been suggested to explain observed differences in continental rift style and the varying morphologies of passive margins. The manner and relative significance of how these suggested controls actually impact tectonic processes and passive margin formation are still a subject of ongoing debate (e.g., Armitage et al, 2010;Brune, 2016;Huismans and Beaumont, 2014;Karner et al, 2007;Svartman Dias et al, 2015). Utilizing simplified kinematic models of uniform, instantaneous extension, McKenzie and Bickle (1988) and White and McKenzie (1989) suggested that mantle potential temperature acts as the first-order control on the magnitude of syn-rift volcanism during continental breakup.…”