中国科学院地球化学研究所机构知识库

Synchrotron-based high pressure-temperature single-crystal X-ray diffraction experiments to ~24 GPa and 700 K were conducted on eclogitic garnets (low-Fe: Prp28Alm38Grs33Sps1 and high-Fe: Prp14Alm62Grs19Adr3Sps2) and omphacites (low-Fe: Quad57Jd42Ae1 and high-Fe: Quad53Jd27Ae20), using externally-heated diamond anvil cell. Fitting the pressure-volumetemperature data to a third-order Birch-Murnaghan equation of state yields the thermoelastic parameters including bulk modulus (KT0), its pressure derivative (K′T0), temperature derivative ((∂KT/∂T)P) and thermal expansion coefficient (αT). The densities of the high-Fe and low-Fe eclogites were then modeled along typical geotherms of the normal mantle and the subducted oceanic crust to the transition zone depth (550 km). The metastable low-Fe eclogite could be a reason for the stagnant slabs within the upper range of the transition zone. Eclogite would be responsible for density anomalies within 100-200 km in the upper mantle of Asia.