Seismic properties of highly strained marbles from the Splügenpass, central Alps

Seismic reflection profiling across the Central Alps (NFP20) shows strong reflectors, some of which correspond to a Mesozoic marble zone which underlies the contact between the Tambo and Suretta nappes. By means of experimental velocity measurements at confining pressures up to 300 MPa on rock samples collected in the marble zone, we determined the seismic properties of these marbles and calculated their reflection coefficients, in order better to constrain the seismic interpretation. in findings are as follows: 1. bles exhibit Vp anisotropy up to 9%, with orthorhombic or transverse isotropic (tetragonal) symmetry due to the crystallographic preferred orientation of calcite. pressional waves, shear waves, and shear wave splitting are very sensitive to the type of fabric (presence or absence of an r-axes concentration). erfaces between marbles and amphibolites or orthogneisses could be good reflectors in normal incidence reflection.