This study focused on the surface microtextures of quartz grains deposited by dam-break floods in Jiacha Gorge, situated in the middle reaches of the Yarlung Tsangpo River. Utilizing a scanning electron microscope (SEM), 200 quartz grains were observed and analyzed based on their microtextural features. Our findings reveal specific microtextures—such as angular outlines, high relief, flat cleavage surfaces, conchoidal fractures, and steps—that serve as clear indicators of the extreme energy associated with dam-break floods in Jiacha Gorge, distinguishing them from meteorological floods and smaller-scale dam-break events. These features also facilitate the differentiation of dam-break flood deposits from those of other sedimentary environments. This research demonstrates that quartz microtextures are a valuable tool for reconstructing sediment transport processes during extreme flood events. We recommend integrating microtextural analysis with complementary methods to refine interpretations and address methodological uncertainties in future studies.