Self-organized criticality of the Olon Ovoot gold-mineralizing system, located in southern Mongolia, was examined employing field mapping, strain analysis, and stable isotope systematics. Stable isotope data suggest metamorphic fluids (7.8‰≤δ¹⁸O≤10.6‰ and -33.7‰≤ δD≤-47.8‰) feeding steadily into the system. Reconstruction of incremental strain axes at the time of gold mineralization (dY=27/106, dX=59.5/322, and dZ=15.5/204) reveals plane, coaxial strain environment. Under such strain state, fluids were likely buffered by rocks in closed systems, as indicated by locally homogeneous oxygen isotope systematics of vein ankerite (δ¹⁸O _ank=22.3±0.5‰). Fluids might also have episodically redistributed in fluid-buffered, open systems under isothermal conditions, as evidenced by uniform oxygen isotope compositions of vein quartz (δ ¹⁸O_qtz=15.9±0.7‰) and complex web of fault-fill and extensional lodes. It was during these transient episodes of fluid advection and gold lode formation that the system potentially self-organized into its critical state.