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The Carlin-type deposits in Nevada (western USA) constitute the world’s second-largest gold ore province. These structurally and stratigraphically controlled, sediment-hosted ore bodies are characterized by carbonate dissolution attending hydrothermal precipitation of gold-rich arsenian pyrite. The origin of the mineralizing fluids and the source of the gold remain debated. Conceptual models, favoring either sedimentary, metamorphic, or magmatic fluid sources, are based on isotopic tracers, giving ambiguous results. Here we use the trace element compositions of fluid inclusions to separate geochemical signals of the large-scale fluid source from effects of deposit-scale fluid interaction with the sedimentary host rocks. Specifically, we compare the ratios of Rb, K, B, As, Sr, and Ba between clearly magmatic-hydrothermal Cu-Au ores at Copper Canyon in the Battle Mountain–Eureka trend with the Gold Quarry …