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Journal Articles Tectonophysics Year : 2008

Continental rifting as a function of lithosphere mantle strength

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Jean-Pierre Brun
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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.

Dates and versions

insu-00351070 , version 1 (08-01-2009)

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Frédéric Gueydan, Christina Morency, Jean-Pierre Brun. Continental rifting as a function of lithosphere mantle strength. Tectonophysics, 2008, 460 (1-4), pp.83-93. ⟨10.1016/j.tecto.2008.08.012⟩. ⟨insu-00351070⟩
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