minerals Article Seismic Properties of a Unique Olivine-Rich Eclogite in the Western Gneiss Region, Norway Yi Cao 1,*, Haemyeong Jung 2 and Jian Ma 1 1 State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Sciences, China University of Geosciences, Wuhan 430074, China;
[email protected] 2 Tectonophysics Laboratory, School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, Korea;
[email protected] * Correspondence:
[email protected] Received: 24 July 2020; Accepted: 29 August 2020; Published: 31 August 2020 Abstract: Investigating the seismic properties of natural eclogite is crucial for identifying the composition, density, and mechanical structure of the Earth’s deep crust and mantle. For this purpose, numerous studies have addressed the seismic properties of various types of eclogite, except for a rare eclogite type that contains abundant olivine and orthopyroxene. In this contribution, we calculated the ambient-condition seismic velocities and seismic anisotropies of this eclogite type using an olivine-rich eclogite from northwestern Flemsøya in the Nordøyane ultrahigh-pressure (UHP) domain of the Western Gneiss Region in Norway. Detailed analyses of the seismic properties data suggest that patterns of seismic anisotropy of the Flem eclogite were largely controlled by the strength of the crystal-preferred orientation (CPO) and characterized by significant destructive effects of the CPO interactions, which together, resulted in very weak bulk rock seismic anisotropies (AVp = 1.0–2.5%, max. AVs = 0.6–2.0%). The magnitudes of the seismic anisotropies of the Flem eclogite were similar to those of dry eclogite but much lower than those of gabbro, peridotite, hydrous-phase-bearing eclogite, and blueschist.