Ha-Myeong Jeong

The interpretation of seismic anisotropy in Earth's upper mantle has traditionally been based on the fabrics (lattice-preferred orientation) of relatively water-poor olivine. Here we show that when a large amount of water is added to olivine, the relation between flow geometry and seismic anisotropy undergoes marked changes. Some of the puzzling observations of seismic anisotropy in the upper mantle, including the anomalous anisotropy in the central Pacific and the complicated anisotropy in subd

Seismic anisotropy has been widely observed in crust and mantle materials and plays a key role in the understanding of structure and flow patterns. Although seismic anisotropy can be explained by the crystal preferred orientation (CPO) of highly anisotropic minerals in the crust, that is, amphibole, experimental studies on the CPO of amphibole are limited. Here we present the results of novel experiments on simple shear deformation of amphibolite at high pressure and temperatures (1 GPa, 480-700

Dehydration embrittlement of serpentine was investigated by employing triaxial deformation experiments at high pressure and temperature (P = 1–6 GPa; T = 550–820ºC). A modified Griggs apparatus was used up to 3.4 GPa and a Walker-type multi-anvil apparatus was used at 3.5–6 GPa). The investigated specimen is a serpentinized peridotite from Val Malenco, Italy. Dehydration of the sample under differential stress resulted in faults associated with ultrafine-grained solid reaction products, formed a

Chlorite peridotites from Almklovdalen in SW Norway were studied to understand the deformation processes and seismicanisotropy in the upper mantle. The lattice preferred orientation (LPO) of olivine and chlorite was determined using electronbackscattered diffraction (EBSD)/scanning electron microscope. A sample with abundant garnet showed [100] axes ofolivine aligned sub-parallel to lineation, and [010] axes aligned subnormal to foliation: A-type LPO. Samples rich in chloriteshowed different oli

Abstract The crystal preferred orientation (CPO) of amphibole has a large effect on seismic anisotropy in the crust. Previous studies have reported four CPO types (I–IV) of amphibole, but the genesis of type IV CPO, which is characterized by [100] axes aligned in a girdle subnormal to the shear direction, is unknown. In this study, shear deformation experiments on amphibolite were conducted to find the genesis of type IV CPO at high pressure (0.5 GPa) and temperature (500–700 °C). The type IV CP

Water is known to change the lattice-preferred orientation (LPO) of olivine, which significantly affects seismic anisotropy in the Earth's upper mantle. Research into the LPO of olivine in the deep interior of the Earth has been limited due to inadequate specimens. We report both the water-induced LPOs of olivine and the presence of large quantities of water inside olivine, enstatite, and garnet in garnet peridotites from the North Qaidam ultrahigh-pressure (UHP) collision belt in NW China. We s