Juvenile water refers to water that is released from magma during volcanic activity and is not part of the existing hydrological cycle. This water originates from the Earth’s mantle and is considered “new” to the Earth’s surface environment. Juvenile water is important in volcanology, hydrogeology, and the study of the Earth’s deep water cycle.
Reference: Fyfe, W. S., Price, N. J., & Thompson, A. B. (1978). Fluids in the Earth’s Crust: Their Significance in Metamorphic, Tectonic and Chemical Transport Processes. Elsevier.