Abstract : The role of the uppermost mantle strength in the pattern of lithosphere rifting is investigated using a thermo-mechanical finite-element code. In the lithosphere, the mantle/crust strength ratio (SM/SC) that decreases with increasing Moho temperature TM allows two strength regimes to be defined: mantle dominated (SM > SC) and crust dominated (SM < SC). The transition between the two regimes corresponds to the disappearance of a high strength uppermost mantle for TM > 700 °C. 2D numerical simulations for different values of SM/SC show how the uppermost mantle strength controls the style of continental rifting. A high strength mantle leads to strain localisation at lithosphere scale, with two main patterns of narrow rifting: "coupled crustmantle" at the lowest TM values and "deep crustal décollement" for increasing TM values, typical of some continental rifts and non-volcanic passive margins. The absence of a high strength mantle leads to distributed deformations and wide rifting in the upper crust. These numerical results are compared and discussed in relation with series of classical rift examples.
https://hal-insu.archives-ouvertes.fr/insu-00351070 Contributor : Isabelle DubigeonConnect in order to contact the contributor Submitted on : Thursday, January 8, 2009 - 1:47:34 PM Last modification on : Tuesday, October 19, 2021 - 6:57:17 PM
Frédéric Gueydan, Christina Morency, Jean-Pierre Brun. Continental rifting as a function of lithosphere mantle strength. Tectonophysics, Elsevier, 2008, 460 (1-4), pp.83-93. ⟨10.1016/j.tecto.2008.08.012⟩. ⟨insu-00351070⟩