Origin and Evolution of Ultramafic Rocks along the Sagaing Fault, Myanmar  

作　　者：Tomoaki Morishita Hnin Min Soe Hla Htay Than Htut Lwin Juan Miguel Guotana Akihiro Tamura Tomoyuki Mizukami Khin Zaw 无 

机构地区：[1]Faculty of Geosciences and Civil Engineering,Kanazawa University,Kanazawa,920-1192,Japan [2]Lamont-Doherty Earth Observatory,Columbia University,Palisades,NY,10964,USA [3]Volcanoes and Earth’s Interior Research Center,Japan Agency for Marine-Earth Science and Technology,2-15 Natsushima,Kanagawa,237-0061,Japan [4]Geology Department,University of Mandalay,Mandalay,05092,Myanmar [5]Geology Department,Dagon University,North Dagon,11422,Myanmar [6]Taunggoke Degree College,Taunggoke,Taunggoke Township,07161,Myanmar [7]Graduate School of Natural Science and Technology,Kanazawa University,Kanazawa,Ishikawa,920-1192,Japan [8]CODES ARC Centre of Excellence in Ore Deposits,University of Tasmania,Tasmania,7001,Australia

出　　处：《Journal of Earth Science》2023年第1期122-132,共11页地球科学学刊（英文版）

基　　金：supported by a Grants-in-Aid for Scientific Research from the Ministry of Education Culture, Sports, Science and Technology of Japan, awarded to T.M. (Nos. 16H05741 and 19H01990);Sakura Science Plane 2018 of Japan Science and Technology Agency (JST);Kanazawa University SAKIGAKE 2018。

摘　　要：The active Sagaing fault in Myanmar defines the boundary between the Indian Plate and the Eurasian Plate and causes seismic damage in the major cities of Myanmar. Small bodies of serpentinite occur along the fault. We for the first time investigated the highly sheared serpentinite bodies in the Sheinmagar area and Yega Inn area along the Sagaing fault. Extensively sheared/brecciated serpentinites and related rocks, such as talc and/or chlorite-bearing rocks contains small rock fragments of serpentinites. Serpentine texture and mineral chemistry indicate that the protolith of these serpentinites were mainly harzburgite with minor amounts of dunite, some of which are cut by gabbroic veins. No shape-preferred orientation of the antigorite is present, indicating that the serpentinization was occurred under relatively static conditions. Protolith and serpentine minerals are similar to those of the jadeitite-bearing serpentinites in the north of the Sagaing fault(the Jade Mine belt). Chemical variations of spinels in the studied area are within the compositional range of forearc peridotites and those in the mantle section of nearby ophiolites. After the formation of antigorite serpentinite under static conditions, these serpentinites were subsequently, but locally deformed, probably due to the activity of the Sagaing fault, resulting in the formation of serpentinite schist/brecciated rock. The presence of the less-deformed antigorite serpentinite in the sheared/brecciated zone indicates the strain localization mainly along the surrounding serpentine-talc(±chlorite) schistose rocks, which is probably formed by the reaction between serpentinite and country rocks. Further studies are needed to better understand whether the distribution of serpentinized peridotites cause variations in the activity of the Sagaing fault.

关 键 词：Sagaing fault SERPENTINITE DEFORMATION OPHIOLITE 

分 类 号：P58[天文地球—岩石学]