Seismic Properties from EBSD Data and Receiver Function Analyses: Results from a Crustal-Scale Detachment System, Aegean Region
Seismic Properties from EBSD Data and Receiver Function Analyses: Results from a Crustal-Scale Detachment System, Aegean Region
Previously Published Material: Only part of the results were previously reported, at the Geological Society of America Annual Meeting (Denver, CO) in 2013. These findings are not yet submitted to any journal.
Abstract ID#: 33472
English Abstract:
The crystallographic preferred orientations were measured on a suite of samples representative of different structural depths along the West Cycladic Detachment System of Greece. Electron backscatter diffraction (EBSD) analyses were conducted on calcitic and mica schists, impure quartzites, and a blueschist, and average seismic properties of the rocks were calculated with the Voigt-Reuss-Hill average of the single minerals’ elastic stiffness tensor. The calcitic and quartzitic rocks have P- and S-wave velocity anisotropies (AVp, AVs) averaging 8.1% and 7.1%, respectively. The anisotropy increases with depth as represented by the blueschist, with AVp averaging 20.3% and AVs averaging 14.5%, due to the content of aligned glaucophane and mica, which strongly control the rock seismic properties. Localised anisotropies of high magnitudes are caused by the presence of mica schists as they possess the strongest anisotropies, with values of 26.6% for AVp and 23.9% for AVs. The direction of the fast and slow P-wave velocities occurs parallel and perpendicular to foliation, respectively, for most samples. The fast propagation has the same NE-SW orientation as the lithospheric stretching direction experienced by the Cyclades since the Late Oligocene. The maximum shear wave anisotropy is subhorizontal, similarly concordant with mineral alignment that developed during extension in the Aegean. Our results strongly favour radial anisotropy in the Aegean mid-crust over azimuthal anisotropy. Receiver functions (RF) for several stations in the Cyclades have been calculated to characterize the underlying crustal structures, such as anisotropy. We present preliminary results of RF post-processing, which will be used in conjunction with velocities and anisotropies from our EBSD data to build a seismic velocity model. This model, based on rock textures and seismic observations, will be helpful for understanding the crustal structure of an extensional province.