WU Xiuling,HAN Yujing,MENG Dawei,YANG Weiran and LI DouxingTest Center and Faculty of Earth Sciences,China University of Geosciences,Wuhan 430074,HubeiLaboratory of Atomic Imaging of Solids,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110015,Liaoning
P588.125
Transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM) analyses have been performed on omphacite from ultra-high pressure (UHP) eclogites at the locality of Shima, Dabie Mountains, China. TEM reveals that the microstructures consist dominantly of dislocation substructures, including free dislocations, loops, tiltwalls, dislocation tangles and subboundaries. They were produced by high-temperature ductile deformation, of which the main mechanism was dislocation creep. Antiphase domain (APD) boundaries are common planar defects; an age of 470±6 Ma for UHP eclogite formation has been obtained from the equiaxial size of APDs in ordered omphacites from Shima, coincident with ages given by single-zircon U-Pb dating (471±2 Ma). HRTEM reveals C2/c and P2ln space groups in different parts of one single omphacite crystal, and no exsolution is observed in the studied samples, which is attributed to rapid cooling. It is suggested that the UHP eclogites underwent a long
WU Xiuling, HAN Yujing, MENG Dawei, YANG Weiran, LI DouxingTest Center, Faculty of Earth Sciences, China University of Geosciences, Wuhan, HubeiLaboratory of Atomic Imaging of Solids, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, Liaoning.2000. TEM and HRTEM Study of Microstructures in Omphacite from UHP Eclogites at Shima, Dabie Mountains, China[J]. Acta Geologica Sinica(),74(2):154-162
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