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Description: We present a 250 ky record of episodic fluid flow along the Malpais fault which hosts the Beowawe hydrothermal system, Nevada, USA. Samples show partial resetting of the apatite (U-Th)/He thermochronometer in a 40 m wide zone around the Malpais fault. Numerical models indicate that, using current fluid temperatures and discharge rates, fluid flow events lasting 2000 years or more would lead to fully reset samples. Episodic fluid pulses lasting 1000 years resulted in partially reset samples, with ~36 individual fluid pulses required to match the data. Episodic fluid flow is also supported by an overturned geothermal gradient in a borehole that crosses the fault, and by breaks in stable isotope trends in hydrothermal sinter deposits that coincide with two independently dated earthquakes in the last 20 ky. This suggests a system where fluid flow is triggered by repeated seismic activity and seals itself over ~1000 years due to formation of clay minerals and silicates in the fault damage zone. Hydrothermal activity is younger than the 6-10 Ma age of the fault. This suggests that the onset of deep (~5 km) fluid flow was initiated only after a large part of the total of 230 m offset took place.