FN Archimer Export Format
PT J
TI Hydrous fluids down to the semi-brittle root zone of detachment faults in nearly amagmatic ultra-slow spreading ridges
BT 
AF Bickert, Manon
   Cannat, M.
   Brunelli, D.
AS 1:1;2:2;3:1,3;
FF 1:;2:;3:;
C1 Dipartimento di Scienze Chimiche e Geologiche, Università di Modena e Reggio Emilia, Modena, Italy
   Université Paris Cité, Institut de Physique du Globe de Paris, CNRS-UMR, 7154, France
   IGAG-CNR, Istituto di Geologia Ambientale e Geoingegneria, Rome, Italy
C2 UNIV MODENA & REGGIO EMILIA, ITALY
   UNIV PARIS CITE, FRANCE
   IGAG CNR, ITALY
IF 3.5
TC 3
UR https://archimer.ifremer.fr/doc/00821/93297/99980.pdf
LA English
DT Article
CR MD 183 / SMOOTHSEAFLOOR
   ROVSMOOTH
BO Marion Dufresne
   Pourquoi pas ?
DE ;Southwest Indian Ridge;Plate boundary faulting;Deformation processes;Hydration;Amphiboles;Fluid -rock interaction;Brittle-ductile transition
AB At the Eastern part of the Southwest Indian Ridge (SWIR), plate divergence is accommodated by large offset normal faults, also called detachment faults, that exhume mantle-derived rocks on the seafloor. A third of the ultramafic samples dredged on- and off-axis in this nearly amagmatic ridge setting present amphibole-bearing secondary mineralogical assemblages indicative of hydration, and for the most part predating the growth of serpentine minerals. The deepest evidence of hydration is the occurrence of small amounts of syn-kinematic amphibole in microshear zones with strongly reduced grain size, which record deformation at high stress and high temperatures (>800 °C) at the root zone of the detachment. The composition of these amphiboles is consistent with a hydrothermal origin, suggesting that seawater derived fluids percolated down to the root of detachment faults, at the Brittle-Ductile Transition (BDT). We propose that the constant exhumation of new mantle material to the seafloor, and the limited lifetime of each detachment (1–3 Myrs) prevent a more pervasive deep hydration of mid-ocean ridge detachment root regions, as proposed at transform fault plate boundaries. 
PY 2023
PD APR
SO Lithos
SN 0024-4937
PU Elsevier BV
VL 442-443
UT 000949885400001
DI 10.1016/j.lithos.2023.107084
ID 93297
ER

EF