Elastic anisotropies of rocks in a subduction and exhumation setting

Abstract. Subduction and exhumation are key processes in the formation of orogenic systems across world, for example, European Alps. For geophysical investigations these orogens, it is essential to understand petrophysical properties rocks involved. These result a complex interaction mineral composition rock fabric including textures (i.e., crystallographic preferred orientations). In this study we present texture-derived elastic anisotropy data representative set different lithologies involved Alpine orogeny. Rock samples were collected Lago di Cignana area Valtournenche, Italian northwestern At locality wide range units continental oceanic origin with varying paleogeographic affiliations tectono-metamorphic histories accessible. Their determined by time-of-flight neutron diffraction. From calculated. The includes from subduction-exhumation setting. subducted originating crust, P-wave anisotropies (AVPs [%]) 1.4 % 3.7 average velocities 7.20–8.24 km/s VP / VS ratios 1.70–1.75. metasediments former accretionary prism AVPs 7.1 %, 6.66–7.23 1.61–1.76. Continental crust which incorporated collisional orogen shows AVP ranging 2.1 6.52–6.62 1.56–1.60. Our results suggest that mafic felsic subduction zones at depth may be discriminated combination seismic signatures: lower higher ratio rocks, metasediments.