New advances in using seismic anisotropy, mineral physics and geodynamics to understand deformation in the lowermost mantle - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Journal of Geodynamics Année : 2011

New advances in using seismic anisotropy, mineral physics and geodynamics to understand deformation in the lowermost mantle

Résumé

The D" region, which lies in the lowermost few hundred kilometres of the mantle, is a central cog in the Earth's heat engine, influencing convection in the underlying core and overlying mantle. In recent years dense seismic networks have revealed a wealth of information about the seismic properties of this region, which are distinct from those of the mantle above. Here we review observations of seismic anisotropy in this region. In the past it has been assumed that the region exhibits a simple form of transverse isotropy with a vertical symmetry axis (VTI anisotropy). We summarise new methodologies for characterising a more general style of anisotropy using observations from a range of azimuths. The observations can be then used to constrain the mineralogy of the region and its style of deformation by a lattice preferred orientation (LPO) of the constituent minerals. Of specific interest is the recent discovery of the stability of the post-perovskite phase in this region, which might explain many enigmatic properties of D". Mantle flow models based on density models derived from global tomographic seismic velocity models can be used to test plausible mineralogies, such as post-perovskite, and their deformation mechanisms. Here we show how linked predictions from mineral physics, geodynamical modelling and seismic observations can be used to better constrain the dynamics, mineralogy and physical properties of the lowermost mantle.
Fichier principal
Vignette du fichier
PEER_stage2_10.1016%2Fj.jog.2011.04.003.pdf (13.06 Mo) Télécharger le fichier
Origine : Fichiers produits par l'(les) auteur(s)
Loading...

Dates et versions

hal-00780031 , version 1 (23-01-2013)

Identifiants

Citer

Andy Nowacki, James Wookey, J-Michael Kendall. New advances in using seismic anisotropy, mineral physics and geodynamics to understand deformation in the lowermost mantle. Journal of Geodynamics, 2011, 52 (3-4), pp.205. ⟨10.1016/j.jog.2011.04.003⟩. ⟨hal-00780031⟩

Collections

PEER
64 Consultations
142 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More