FN Archimer Export Format
PT J
TI Geological context and vents morphology of the ultramafic-hosted Ashadze hydrothermal areas (Mid-Atlantic Ridge 13 degrees N)
BT 
AF ONDREAS, Helene
   CANNAT, Mathilde
   FOUQUET, Yves
   NORMAND, Alain
AS 1:1;2:2;3:1;4:1;
FF 1:PDG-REM-GM-LGM;2:;3:PDG-REM-GM-LGM;4:PDG-REM-GM-CTDI;
C1 IFREMER, Ctr Brest, FR-29280 Plouzane, France.
   Univ Paris Diderot, CNRS, Inst Phys Globe Paris, UMR 7154, FR-75238 Paris 05, France.
C2 IFREMER, FRANCE
   UNIV PARIS 07, FRANCE
SI BREST
SE PDG-REM-GM-LGM
   PDG-REM-GM-CTDI
IN WOS Ifremer jusqu'en 2018
   copubli-france
   copubli-univ-france
IF 2.94
TC 22
TU Centre national de la recherche scientifique
   Institut National de l'Information Géographique et Forestière
   Institut de physique du globe
   Université Paris Diderot
   Université Pierre et Marie Curie
   Université de La Réunion
UR https://archimer.ifremer.fr/doc/00111/22223/19895.pdf
LA English
DT Article
CR SERPENTINE
BO Pourquoi pas ?
DE ;Ashadze;Mid-Atlantic Ridge;hydrothermal activity;hydrothermal explosion crater;ultramafic rocks
AB Recent ROV dives and high-resolution bathymetric data acquired over the Ashadze fields on the Mid-Atlantic Ridge (13 degrees N) allow us to derive constraints on the regional and local geological setting of ultramafic-hosted hydrothermal fields. The active vent fields of Ashadze hydrothermal fields are located in the western axial valley wall, downslope from the termination of a prominent corrugated surface and in a transitional domain with respect to ridge segmentation. The study of the shipboard and ROV bathymetry shows that decameter (100 m by 60 m) to kilometer-scaled rockslides shape the axial valley wall slopes in this region. The Ashadze 1 vent field occurs on a coherent granular landslide rock mass that is elongated in an E-W direction. The Ashadze 1 vent field comprises hundreds of active and inactive sulfide chimneys. The Ashadze 2 vent field is located in a NNE-trending linear depression which separates outcrops of gabbros and serpentinized peridotites. Active black smokers in the Ashadze 2 field are located on ultramafic substratum in a 40-m diameter crater, 5-m deep. This crater recalls similar structures described at some vents of the Logatchev hydrothermal field (Mid-Atlantic Ridge 15 degrees N). We discuss the mode of formation for these craters, as well as that for a breadcrust-like array of radial fissures identified at Ashadze 1. We propose that hydrothermalism at Ashadze can be an explosive phenomena associated with geyser-like explosions. Our study also constrains the geological and geophysical context of the ultramafic-hosted Ashadze hydrothermal system that may use the oceanic detachment fault as a preferred permeability conduit.
PY 2012
PD NOV
SO Geochemistry Geophysics Geosystems
SN 1525-2027
PU Amer Geophysical Union
VL 13
IS 1
UT 000310962100004
DI 10.1029/2012GC004433
ID 22223
ER

EF