Lithium isotopes in Guatemalan and Franciscan HP-LT Rocks:

Insights into the role of sediment-derived fluids in the mantle wedge

Proto Melange

Shear zone between plates

Altered Ocean Crust

Oceanic Sediments

After Bebout (2007)

Subduction Fluid Trace Element Patterns

HP-LT Rocks in Guatemala

Dehydra

tion of Slab

Shear zone between plates

Altered Ocean Crust

Oceanic Sediments

Physical Model Prograde

Physical Model Retrograde

Dehydra

tion of Slab

Shear zone between plates

Altered Ocean Crust

Oceanic Sediments

South have lawsonite cold and wet @ peak conditions (~480°C)

Very high pressure rocks just shy of coesite (UHP) field

North saw slightly higher-T (<550°C) with a second metamorphic event

Eclogites

JadeititesAppear to follow down-pressure trend from associated Lws-eclogites and blueschist-eclogites

South contains qtz higher P.

South T ≥ 200°C.

North T = 300-400°C

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Li systematics in Guatemala

MORBIAB

Guatemala Eclogite Avg.