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Pumpellyite from the oceanic crust, DSDP/ODP Hole 504B

H. Ishizuka
Pumpellyite from the oceanic crust, DSDP/ODP Hole 504B
Mineralogical Magazine (December 1999) 63 (6): 891-900


Pumpellyite has been found in doleritic basalt of a sheeted dyke complex drilled from 2072.1 m below sea floor in DSDP/ODP Hole 504B, south of the Costa Rica Rift, eastern Pacific. It occurs as fine-grained crystal aggregates accompanied by albite, chlorite and chalcopyrite, which partially replace a plagioclase phenocryst (An (sub 85-88) ) that is also associated with primary magnetite. Chemical compositions of the pumpellyite vary antithetically in relation to Fe (super *) and Al as well as Fe (super *) and Mg, indicating the dominant substitution of Fe (super 3+) by Al with the minor substitution of Fe (super 2+) by Mg. Such compositional variations overlap with those of prehnite-pumpellyite facies rocks dredged from other oceanic ridges and intra-oceanic arcs, and those of similar facies rocks from ophiolites, but are aluminous compared with those of zeolite facies metabasites in ophiolites. These observations suggest that the breakdown of the plagioclase phenocryst and magnetite in the presence of a Cu- and S-bearing fluid phase led to the formation of pumpellyite + albite + chlorite + chalcopyrite during oceanic ridge hydrothermal alteration.

ISSN: 0026-461X
EISSN: 1471-8022
Serial Title: Mineralogical Magazine
Serial Volume: 63
Serial Issue: 6
Title: Pumpellyite from the oceanic crust, DSDP/ODP Hole 504B
Author(s): Ishizuka, H.
Affiliation: Kochi University, Department of Geology, Kochi, Japan
Pages: 891-900
Published: 199912
Text Language: English
Publisher: Mineralogical Society, London, United Kingdom
References: 25
Accession Number: 2000-026819
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, sketch map
N00°00'00" - N10°00'00", W85°00'00" - W80°00'00"
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200009
Program Name: ODPOcean Drilling Program
Program Name: DSDPDeep Sea Drilling Project
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