Lawsonite Blueschist
“Cold subduction's water-rich signature”
Lawsonite blueschist is a variety of blueschist containing the calcium aluminum silicate mineral lawsonite, which is stable only at high pressures and low temperatures. Lawsonite carries significant water into subduction zones and its breakdown at greater depths releases fluids that trigger melting in the overlying mantle.
lawsonite, glaucophane, phengite, chlorite, titanite, epidote, aragonite
Franciscan Complex (California, USA), Tavşanlı Zone (Turkey), New Caledonia, Corsica (France), Dominican Republic
5-6
Lawsonite can contain up to 11.5% water by weight — more than almost any other rock-forming silicate mineral — making it one of the most important carriers of water into Earth's deep mantle during subduction.
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