Prehnite-Pumpellyite facies

Index Minerals

Prehnite, Laumontite, Wairakite

Required Geological Setting

Accretionary complexes

Accretionary complexes + Middle-P metamorphic rocks

Accretionary complexes + Low-P metamorphic rocks

Occurrence

Metamorphic rocks formed by burial or regional metamorphism in the following condition: 200-350 degree and 0.2-0.4 GPa (5-15 km depth). A metamorphic facies formed in oceanic crusts at subseafloor near mid-ocean ridges. Prehnite-Pumpellyite facies metamorphic rocks are in accretionary complexes near the boundaries of Barrovian-type middle-P metamorphic rocks and Ryoke-type low-P metamorphic rocks.

Change of mineral assemblages

• [ Extinct ] Heulandite, Analcime, Celadonite, Illite/Smectite
• [ Appear ] Prehnite, Pumpellyite, Albite, Laumontite, Wairakite, Epidote, Illite/Chlorite, Antigorite, Talc

Mineral Assemblages

• [ Felsic Rocks ] Quartz, Illite/Chlorite, Albite, Pumpellyite, Epidote, (Stilpnomelane)
• [ Mafic Rocks ] Illite/Chlorite, Prehnite, Albite, Pumpellyite, Epidote, Laumontite, Wairakite, (Calcite, Datolite, Yugawaralite)
• [ Ultramafic Rocks ] Clinochlore, Serpentine (Chrysotile, Lizardite), Talc
• [ Mudstone ] Illite/Chlorite, Albite, Quartz, Graphite
• [ Laterite ]
• [ Bedded Mn ] Pumpellyite-(Mn), Braunite/Hausmannite, Caryopilite, Rhodochrosite, Quartz, (Piemontite)
• [ Carbonate Rocks ] Calcite/Dolomite, Quartz, Talc