Exsolution microstructures in ultrahigh-pressure rocks:Progress, controversies and challenges  

作　　者：LIU Liang YANG JiaXi ZHANG JunFeng CHEN DanLing WANG Chao YANG WenQiang 

机构地区：[1]State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi'an 710069, China [2]College of Earth Sciences and Land Resources, Chang'an University, Xi'an 710054, China [3]State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China

出　　处：《Chinese Science Bulletin》2009年第12期1983-1995,共13页

基　　金：Supported by a special grant from the Ministry of Science and Technology of China for the State Key Laboratory of Continental Dynamics of Northwest University,National Basic Research Program of China(Grant No.2009CB825003);National Natural Science Foundation of China(Grant Nos.40572111,40372088,40472043and40502021)

摘　　要：Exsolution microstructures in minerals of rocks from orogenic belts played an important role in recognition of ultrahigh-pressure (UHP) metamorphism in their host rocks by defining the subduction depth and improving our understanding of the dynamics during the subduction and exhumation of UHP rocks. However, it is a challenging scientific topic to distinguish the 'exsolution microstructures' from the 'non-exsolution microstructures' and decipher their geological implications. This paper describes the subtle differences between the 'exsolution microstructures' and the 'non-exsolution microstructures' and summarizes the progress in studies of exolution microstructures from UHP rocks and mantle rocks of ultra-deep origin. We emphasize distinguishing the 'exsolution microstructures' from the 'non-exsolution microstructures' based on their geometric topotaxy and chemistry. In order to decipher correctly the exsolution microstructures, it is crucial to understand the changes of chemistry and habits of host minerals with pressure and temperature. Therefore, it is important to combine observations of exsolution microstructure in natural rocks with experimental results at high pressure and temperature and results of micro-scale analyses. Such studies will improve our understanding of the UHP metamorphism and cast new lights on solid geoscience issues such as deep subduction of continental crusts and crust-mantle interactions.Exsolution microstructures in minerals of rocks from orogenic belts played an important role in recognition of ultrahigh-pressure （UHP） metamorphism in their host rocks by defining the subduction depth and improving our understanding of the dynamics during the subduction and exhumation of UHP rocks. However, it is a challenging scientific topic to distinguish the ＇exsolution microstructures＇ from the ＇non-exsolution microstructures＇ and decipher their geological implications. This paper describes the subtle differences between the ＇exsolution microstructures＇ and the ＇non-exsolution microstructures＇ and summarizes the progress in studies of exolution microstructures from UHP rocks and mantle rocks of ultra-deep origin. We emphasize distinguishing the ＇exsolution microstructures＇ from the ＇non-exsolution microstructures＇ based on their geometric topotaxy and chemistry. In order to decipher correctly the exsolution microstructures, it is crucial to understand the changes of chemistry and habits of host minerals with pressure and temperature, Therefore, it is important to combine observations of exsolution microstructure in natural rocks with experimental results at high pressure and temperature and results of micro-scale analyses. Such studies will improve our understanding of the UHP metamorphism and cast new lights on solid geoscience issues such as deep subduction of continental crusts and crust-mantle interactions.

关 键 词：超高压岩石 微观结构 超高压变质岩石 超高压变质作用 壳幔相互作用 矿物岩石 科学主题 地质意义 

分 类 号：P588.3[天文地球—岩石学] P54[天文地球—地质学]