Structure and anisotropy of the crust in the Cyclades, Greece, using receiver functions constrained by in situ rock textural data

Abstract

Seismic anisotropy data are often used to resolve rock textures and deformation in the crust based on compilations of rock properties that may not be representative of the local geology. In this paper, we use teleseismic receiver functions jointly with in situ rock property data to constrain the seismic structure and anisotropy of the crust in the Cyclades, Greece, located in the back‐arc region of the Hellenic subduction zone. The receiver function data indicate that the Moho is relatively flat at 25 km depth toward the south and deepens to 33 km in the north, consistent with previous studies, and reveal an intracrustal discontinuity at depths varying from 3 to 11 km, mostly observed in the south central Aegean. Harmonic decomposition of the receiver functions further indicates the presence of both shallow and deep crustal anisotropy related to crustal structures. We model synthetic receiver functions based on constraints from in situ rock properties that we measured using the electron backscatter diffraction technique. Our results indicate that the shallow upper crustal layer is characterized by metapelites with ~5% anisotropy, underlain by a 20 km thick and possibly anisotropic layer of high‐pressure rocks comprising blueschist and eclogite and/or restitic crust resulting from magmatism. This study demonstrates the importance of rock textural data in the interpretation of seismic velocity profiles.

Seismic properties and anisotropy of the continental crust: Predictions based on mineral texture and rock microstructure

“…Examples are recent studies by Cossette et al . [, ], in the Aegean region, and Xie et al . [], in the Basin and Range province.…”

“…Interpretation of seismic anisotropy is often tied to crustal ductile deformation that produces strong preferred alignment of crystallographic axes and hence texture in rocks [e.g., Shapiro et al ., ; Schulte‐Pelkum et al ., ; Nábělek et al ., ; Ozacar and Zandt , ; Endrun et al ., ; Schulte‐Pelkum and Mahan , ]. The integration of seismological results with mineral texture and microstructural information therefore provides a very powerful combination that enables inferences regarding deformation in different tectonic settings that are otherwise not possible [i.e., Moschetti et al ., ; Huang et al ., ; Long , ; Cossette et al ., , ; Xie et al ., ]. A significant challenge lies in extracting the contribution of intrinsic seismic properties resulting from texture and microstructure to the overall seismic signal.…”

Architecture of the crust and uppermost mantle in the northern Canadian Cordillera from receiver functions

“…This step introduces an additional azimuth parameter α , which corresponds to the nonzero phase of the sine and cosine functions [ Audet , ; Cossette et al ., ]. In this study we minimize the energy on B || ; thus, the resolved orientation α is aligned with either the strike of a dipping interface or the fast axis of hexagonal symmetry [ Audet , ; Cossette et al ., ].…”

“…The last two terms C || and C ⊥ are for k = 2 presenting a periodicity of 180°. They indicate a structure characterized by an anisotropic layer with a dominantly horizontal symmetry axis [Shiomi and Park, 2008;Bianchi et al, 2010;Audet, 2015;Cossette et al, 2016]. A medium characterized by a vertical axis of hexagonal symmetry will not produce signal on the k = 1 and 2 components.…”

“…Thus, we can determine the optimal orientation of the coordinate system that coincides with the dominant orientation of structure by minimizing the energy on a particular k = 1 component over a certain depth range, under rotation of the frame of reference. This step introduces an additional azimuth parameter α, which corresponds to the nonzero phase of the sine and cosine functions [Audet, 2015;Cossette et al, 2016]. In this study we minimize the energy on B || ; thus, the resolved orientation α is aligned with either the strike of a dipping interface or the fast axis of hexagonal symmetry [Audet, 2015;Cossette et al, 2016].…”