Semibrittle seismic deformation in high-temperature mantle mylonite shear zone along the Romanche transform fault
|Author(s)||Yu Zhiteng1, Singh Satish C.1, Gregory Emma P. M.1, Maia Marcia2, 3, Wang Zhikai1, Brunelli Daniele4, 5|
|Affiliation(s)||1 : Université de Paris, Institut de Physique du Globe de Paris, CNRS, Paris, France.
2 : CNRS-Université de Bretagne Occidentale, IUEM, France.
3 : Laboratoire Géosciences Océan, CNRS-UBO UMR 6538, Institut Universitaire Européen de la Mer Rue Dumont d’Urville, 29280 Plouzané France.
4 : Università di Modena e Reggio Emilia, Modena, Italy.
5 : Institute for Marine Sciences ISMAR-CNR, Italy.
|Source||Science Advances (2375-2548) (American Association for the Advancement of Science (AAAS)), 2021-04 , Vol. 7 , N. 15 , P. eabf3388 (10p.)|
|WOS© Times Cited||1|
Oceanic transform faults, a key element of plate tectonics, represent the first-order discontinuities along mid-ocean ridges, host large earthquakes, and induce extreme thermal gradients in lithosphere. However, the thermal structure along transform faults and its effects on earthquake generation are poorly understood. Here we report the presence of a 10- to 15-kilometer-thick in-depth band of microseismicity in 10 to 34 kilometer depth range associated with a high-temperature (700° to 900°C) mantle below the brittle lithosphere along the Romanche mega transform fault in the equatorial Atlantic Ocean. The occurrence of the shallow 2016 moment magnitude 7.1 supershear rupture earthquake and these deep microearthquakes indicate that although large earthquakes occur in the upper brittle lithosphere, a substantial amount of deformation is accommodated in the semibrittle mylonitic mantle that resides at depths below the 600°C isotherm. We also observe a rapid westward deepening of this band of seismicity indicating a strong lateral heterogeneity.