The seismically fastest chemical heterogeneity in the Earth's deep upper mantle—implications from the single-crystal thermoelastic properties of jadeite

摘要: Abstract Jadeite is a major mineral phase (up to 50 vol%) in the subducted sediments/crust with continental origin, which are one of heterogeneities and important enriched geochemical reservoirs (such as EM-1 EM-2) for incompatible elements Earth's interior. Identifying locating requires knowledge elastic properties relevant phases at high pressure-temperature conditions. Unfortunately, single-crystal jadeite have never been measured high-pressure conditions, partially due its low crystal symmetry. In this study, we experimentally determined moduli pressures first time up 18 GPa ambient temperature condition using Brillouin spectroscopy. Fitting third-order finite strain equation state velocity-pressure data yields K S 0 ′ =3.9(1), G =1.09(4) ρ =3.302(5) g/cm3, KS0=138(3) GPa, G0=84(2) GPa. addition, also conducted synchrotron X-ray diffraction experiments 25 700 K. The fitting Holland-Powell type thermal-pressure Birch-Murnaghan T =3.8(2) α =3.4(5) ×10−5 K−1. Based on obtained thermoelastic parameters jadeite, density seismic velocities continent-derived modeled depth range from 200 500 km. become extremely fast depths greater than ∼300 km, 11.8% 14.7% faster Vp Vs mantle, 5.6% 7.3% oceanic crust. existence even small amount can result strong anomalies