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Article Dans Une Revue Earth and Planetary Science Letters Année : 2019

Controls on the seafloor exposure of detachment fault surfaces

Jean-Arthur Olive
Ross Parnell-Turner
  • Fonction : Auteur
Javier Escartin
Deborah Smith
  • Fonction : Auteur
Sven Petersen
  • Fonction : Auteur

Résumé

Keywords 19 Mid-ocean ridge; detachment faulting; oceanic core complex; critical taper; fault friction; 20 21 Highlights 22 • A small fraction of corrugated detachment fault surfaces is eventually exposed at the seafloor. 23 • Seafloor slopes indicate effective friction of ~0.15 on shallow part of detachments. 24 • Moderate-offset detachment faults may be largely blanketed by hanging wall material. 25 • Seafloor-shaping processes profoundly alter the morphology of oceanic core complexes. 26 27 28 Abstract 29 While oceanic detachment faults have been proposed to account for the accretion of ~40% of new 30 seafloor in the North Atlantic ocean, clear exposures of large-offset, often-corrugated fault 31 surfaces remain scarce and spatially limited. To help resolve this paradox, we examine the 32 conditions under which detachment fault growth may or may not lead to extensive exposure of 33 corrugated fault planes at the seafloor. Using high-resolution bathymetry from four detachment 34 faults at the northern Mid-Atlantic Ridge, we investigate the rafting of hanging wall-derived debris 35 over emerging fault scarps, which can lead to covering shallow-dipping corrugated fault surfaces. 36 We model this process using critical taper theory, and infer low effective friction coefficients 37 (~0.15) on the shallowest portion of detachment faults. A corollary to this result is that detachments 38 emerging from the seafloor at angles <10º are more likely to become blanketed under an apron of 39 hanging wall material. We generalize these findings as a simple model for the progressive exposure 40 and flexural rotation of detachment footwalls, which accounts for the continued action of seafloor-41 shaping processes. Our model suggests that many moderate-offset, hidden detachment faults may 42 exist along slow mid-ocean ridges, and do not feature an exposed fault surface. 43 44

Domaines

Tectonique
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Dates et versions

hal-02324084 , version 1 (21-10-2019)

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Jean-Arthur Olive, Ross Parnell-Turner, Javier Escartin, Deborah Smith, Sven Petersen. Controls on the seafloor exposure of detachment fault surfaces. Earth and Planetary Science Letters, 2019, 506, pp.381-387. ⟨10.1016/j.epsl.2018.11.001⟩. ⟨hal-02324084⟩
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