Two‐Branch Break‐up Systems by a Single Mantle Plume: Insights from Numerical Modeling

Abstract

Thermomechanical modeling of plume‐induced continental break‐up reveals that the initial location of a mantle anomaly relative to a lithosphere inhomogeneity has a major impact on the geometry and timing of a rift‐to‐spreading system. Models with a warmer Moho temperature are more likely to result in “plume‐centered” mode, where the rift and subsequent spreading axis grow directly above the plume. Models with weak far‐field forcing are inclined to develop a “structural‐inherited” mode, with lithosphere deformation localized at the lateral lithospheric boundary. Models of a third group cultivate two break‐up branches (both “plume‐centered” and “structural inherited”) that form consecutively with a few million years delay. With our experimental setup, this break‐up mode is sensitive to relatively small lateral variations of the initial anomaly position. We argue that one single mantle anomaly can be responsible for nonsimultaneous initiation and development of two rift‐to‐spreading systems in a lithosphere with a lateral strength contrast.

Non‐uniform splitting of a single mantle plume by double cratonic roots: Insight into the origin of the central and southern East African Rift System

“…The initial model setup and geotherm were adopted with respect to observation-based models of regional thermal and rheological structure of the continental lithosphere in East Africa (Albaric, D everch ere, Petit, Perrot, & Le Gall, 2009;Artemieva, 2006;Fishwick & Bastow, 2011;P erez-Gussiny e et al, 2009). Rheological parameters were chosen in consideration of extensive and successful experience obtained from heterogeneous continental rifting (e.g., Huismans & Beaumont, 2007;Wenker & Beaumont, 2016 and references therein) and plume-lithosphere interaction modelling (e.g., Beniest, Koptev, & Burov, 2017;Beniest, Koptev, Leroy, Sassi, & Guichet, 2017;Burov, 2011;Burov & Cloetingh, 2010;Burov & Gerya, 2014;Burov & Guillou-Frottier, 2005;Burov, Guillou-Frottier, d'Acremont, Le Pourhiet, & Cloetingh, 2007;Koptev, Cloetingh, Burov, Franc ßois, & Gerya, 2017) including our previous Africa-oriented experiments (Koptev et al, 2015(Koptev et al, , 2016, which have been able to reproduce a number of key features of the central EARS such as timing, surface velocity distribution and large-scale topography [Colour figure can be viewed at wileyonlinelibrary.com] Kelley, 1998;Pik, Marty, & Hilton, 2006). Yet, the southern prolongation of the Western rift by the Malawi rift has not been reproduced in any of these "one-craton" experiments (Koptev et al, 2015(Koptev et al, , 2016.…”

Plume‐Induced Breakup of a Subducting Plate: Microcontinent Formation Without Cessation of the Subduction Process

“…Repeated jumps of midoceanic ridges toward nearby hot spots within oceanic lithosphere have been reproduced numerically by Mittelstaedt et al (2008Mittelstaedt et al ( , 2011 and observed by d' Acremont et al (2010). Mantle upwelling, thus, was confirmed to be one of the key factors in the contrasting continental rifting characterized by both "passive/amagmatic" and "active/magmatic" branches (see also 3-D experiments by Koptev et al, 2015Koptev et al, , 2016Koptev, Cloetingh, et al, 2018) that may further evolve into breakup centers embracing isolated continental block (Beniest, Koptev, Leroy, et al, 2017). Mantle upwelling, thus, was confirmed to be one of the key factors in the contrasting continental rifting characterized by both "passive/amagmatic" and "active/magmatic" branches (see also 3-D experiments by Koptev et al, 2015Koptev et al, , 2016Koptev, Cloetingh, et al, 2018) that may further evolve into breakup centers embracing isolated continental block (Beniest, Koptev, Leroy, et al, 2017).…”

“…In the context of the continental lithosphere, the 2-D thermo-mechanical modeling by Lavecchia et al (2017) showed an abandonment of the rift initially localized in a preexisting zone of lithospheric weakness and associated rift jump toward the thermally activated mantle plume. Mantle upwelling, thus, was confirmed to be one of the key factors in the contrasting continental rifting characterized by both "passive/amagmatic" and "active/magmatic" branches (see also 3-D experiments by Koptev et al, 2015Koptev et al, , 2016Koptev, Cloetingh, et al, 2018) that may further evolve into breakup centers embracing isolated continental block (Beniest, Koptev, Leroy, et al, 2017). In analog models, a complete separation of the microcontinental body from a parent continent is also strongly connected to the thermal weakening due to the presence of a hot spot (Dubinin et al, 2018).…”

“…Possible mechanisms for intraoceanic ridge-jumps (d'Acremont et al, 2010;Mittelstaedt et al, 2008Mittelstaedt et al, , 2011 and for mid-oceanic ridge jumps to the passive continental margins have been explored by both numerical (Beniest, Koptev & Burov, 2017;Beniest, Koptev, Leroy, et al, 2017;Lavecchia et al, 2017) and analog (Dubinin et al, 2018) modeling studies. Possible mechanisms for intraoceanic ridge-jumps (d'Acremont et al, 2010;Mittelstaedt et al, 2008Mittelstaedt et al, , 2011 and for mid-oceanic ridge jumps to the passive continental margins have been explored by both numerical (Beniest, Koptev & Burov, 2017;Beniest, Koptev, Leroy, et al, 2017;Lavecchia et al, 2017) and analog (Dubinin et al, 2018) modeling studies.…”

“…Over the last decade, several numerical studies have been performed to investigate the origin of microcontinents in extensional settings. Possible mechanisms for intraoceanic ridge-jumps (d'Acremont et al, 2010;Mittelstaedt et al, 2008Mittelstaedt et al, , 2011 and for mid-oceanic ridge jumps to the passive continental margins have been explored by both numerical (Beniest, Koptev & Burov, 2017;Beniest, Koptev, Leroy, et al, 2017;Lavecchia et al, 2017) and analog (Dubinin et al, 2018) modeling studies. However, it is still not apparent how microcontinents form in a convergent tectonic system like Africa during its motion toward Eurasia.…”