Title :

Quasi-3-D Seismic Reflection Imaging and Wide-Angle Velocity Structure of Nearly Amagmatic Oceanic Lithosphere at the Ultraslow-Spreading Southwest Indian Ridge

Author(s) :

Momoh, Ekeabino [Auteur]
Institut de Physique du Globe de Paris [IPGP]
Cannat, Mathilde [Auteur]
Institut de Physique du Globe de Paris [IPGP]
Watremez, Louise [Auteur]
Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 [LOG]
Institut des Sciences de la Terre de Paris [iSTeP]
Leroy, Sylvie [Auteur]
Institut des Sciences de la Terre de Paris [iSTeP]
Singh, Satish [Auteur]
Institut de Physique du Globe de Paris [IPGP]

Journal title :

Journal of Geophysical Research : Solid Earth

Pages :

9511-9533

Publisher :

American Geophysical Union

Publication date :

2017

ISSN :

2169-9313

HAL domain(s) :

Planète et Univers [physics]/Sciences de la Terre/Tectonique

English abstract : [en]

We present results from 3-D processing of 2-D seismic data shot along 100 m spaced profiles in a 1.8 km wide by 24 km long box during the SISMOSMOOTH 2014 cruise. The study is aimed at understanding the oceanic crust formed ...
Show more >We present results from 3-D processing of 2-D seismic data shot along 100 m spaced profiles in a 1.8 km wide by 24 km long box during the SISMOSMOOTH 2014 cruise. The study is aimed at understanding the oceanic crust formed at an end-member mid-ocean ridge environment of nearly zero melt supply. Three distinct packages of reflectors are imaged: (1) south facing reflectors, which we propose correspond to the damage zone induced by the active axial detachment fault: reflectors in the damage zone have dips up to 60° and are visible down to 5 km below the seafloor; (2) series of north dipping reflectors in the hanging wall of the detachment fault: these reflectors may correspond to damage zone inherited from a previous, north dipping detachment fault, or small offset recent faults, conjugate from the active detachment fault, that served as conduits for isolated magmatic dykes; and (3) discontinuous but coherent flat-lying reflectors at shallow depths (<1.5 km below the seafloor), and at depths between 4 and 5 km below the seafloor. Comparing these deeper flat-lying reflectors with the wide-angle velocity model obtained from ocean-bottom seismometers data next to the 3-D box shows that they correspond to parts of the model with P wave velocity of 6.5–8 km/s, suggesting that they occur in the transition between lower crust and upper mantle. The 4–5 km layer with crustal P wave velocities is interpreted as primarily due to serpentinization and fracturation of the exhumed mantle-derived peridotites in the footwall of active and past detachment faults.Show less >

Language :

Anglais

Peer reviewed article :

Oui

Audience :

Internationale

Popular science :

Non

Collections :

• Laboratoire d'Océanologie et de Géosciences (LOG) - UMR 8187

Source :

Harvested from HAL