Seismic anisotropy in an ophiolite peridotite: Application to oceanic upper mantle

摘要: Compressional velocity Vp to 8 kbar and 275°C in a homogeneous, 0.5% porosity, little-altered harzburgite from the Antalya ophiolite complex Turkey was measured along three principal kinematic axes as defined preferred orientations of olivine enstatite. The observed anisotropy 0.7 km/s for pressures P 2 temperatures T 25° 275°C. seismic at 250°C 5 (15-km depth) calculated single-crystal elastic constants fabric data were within 3% velocities core directions. Measured values derivatives cores are 14 m/s −0.6 °C, which reasonable agreement with average data. These result critical thermal gradient 7.5°C/km. A model oceanic crust uppermost mantle (constructed structural this complex) permits an estimation azimuthal beneath paleocrust under assumed conditions 15-km depth. is Δ = 0.3 8.46 8.16 normal parallel ridge, respectively. shear 0.18 km/s. Measurements also presented lherzolite Salt Lake Crater, Hawaii. these agree those obtained harzburgite; however, consistently higher. higher sample considered its porosity.