کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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4694279 | 1636905 | 2008 | 11 صفحه PDF | دانلود رایگان |
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 crust–mantle” 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.
Journal: Tectonophysics - Volume 460, Issues 1–4, 15 November 2008, Pages 83–93