Abstract

• The study area is situated along the Sagaing Fault between the Kannbyu and Yega-Inn areas. The main objective of this study is to emphasize the serpentinite unit of ophiolite suite (Central Ophiolite Belt) along the Sagaing Fault and to discuss their protolith that is related to fault activity. The Sagaing Fault is located at the continental plate boundary between the Myanmar Plate and Sundaland Plate. It is an active fault that causes seismic damage in the major cities of Myanmar. Small outcrop of serpentinites are found in the Kannbyu area and massive bolder in the Yega-Inn (lake) area. They occurred along this fault, and examined the highly sheared serpentinite bodies in the Kannbyu and Yega-Inn areas by the Electron probe micro-analyzer (EPMA). Rock samples from these areas have not been yet up to now by EPMA laboratory analyzed method especially serpentinite units that have not been done in Myanmar. Sheared serpentinites and related rocks: such as talc and chlorite-bearing rocks, show the foliation is defined by alignments of small rock fragments. Sporadically serpentinite units in this area are completely serpentinized, weathered, the morphology and chemistry of their spinels, coupled with micro-texture, indicate that the protolith of these serpentinites are mainly harzburgite and dunite and these units are cut by gabbroic veins in places. Chrome spinel samples showed the variable in chemical composition range of fore-arc peridotites, and they are similar to those in the mantle section of nearby ophiolites. Antigorite serpentine mineral is the main phase of the studied samples. No shape preferred orientation of the antigorite is present, indicating that the serpentinization occurred at ~ 500 °C under relatively static conditions. Locally, these serpentinites were deformed and it is probably due to the activity of the Sagaing Fault, resulting in the formation of serpentinite schist. Serpentinized peridotite and related minerals such as talc and saponite in the research area is probably linked to variations in the activity of the Sagaing Fault.