Prehnite-pumpellyite facies 4212579 57900715 2006-06-10T17:34:26Z Bluebot 527862 Unicodifying using [[Wikipedia:AutoWikiBrowser|AWB]] The '''prehnite-pumpellyite facies''' is a [[Metamorphism|metamorphic facies]] typical of subseafloor alteration of the [[oceanic crust]] around [[mid-ocean ridge]] spreading centres. <!-- Unsourced image removed: [[Image:Metamorphic Facies.JPG|thumb|300px|Metamorphic facies]] --> It is a metamorphic grade transitional between [[zeolite facies]] and [[greenschist facies]] representing a temperature range of 250 to 350 °C and a pressure range of approximately two to seven kilobars. The mineral assemblage is dependent on host composition. *In [[mafic]] rocks the assemblage is [[Chlorite group|chlorite]], [[prehnite]], [[albite]], [[pumpellyite]] and [[epidote]]. *In [[ultramafic]] rocks the assemblage is [[serpentine]], [[talc]], [[forsterite]], [[tremolite]] and chlorite. *In argillaceous sedimentary rocks the assemblage is [[quartz]], [[illite]], albite, and [[stilpnomelane]] chlorite. *In carbonate sediments the assemblage is [[calcite]], [[dolomite]], quartz, [[Clay minerals|clays]], talc, and [[muscovite]]. ==References== * Blatt, Harvey and Robert Tracy, 1995, ''Petrology: igneous, sedimentary, and metamorphic'', Freeman, ISBN 0-7167-2438-3 {{Metamorphic Facies}} [[Category:Metamorphic rocks]] [[Category:Petrology]] {{geology-stub}}