Fluid flow and metasomatism in a subduction zone hydrothermal system: Catalina schist terrane, California

Journal Article · Wed Nov 01 04:00:00 EST 1989 · Geology; (USA)

OSTI ID:6159471

Barton, M D; Bebout, G E ^[1]

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1. Univ. of California, Los Angeles (USA)

On Santa Catalina Island, southern California, bluechist to amphibolite facies metasedimentary, metamafic, and meta-ultramafic rocks show veining and alteration that reflect fluid flow and mass transfer at 25-45 km depths in an Early Cretaceous subduction zone. Synkinematic and postkinematic veins record fluid transport and metasomatism during prograde metamorphism and uplift. Vein and host-rock mineralogy and whole-rock compositions demonstrate large-scale chemical redistribution, especially of Si and alkali elements. Veins and host rocks trend toward isotopic equilibration with aqueous fluids with {delta}{sup 18}O{sub SMOW}=+13{per thousand} {plus minus} 1{per thousand}. The likely source for these fluids is in lower temperature, sediment-rich parts of the subduction zone. Carbon isotope systematics support this conclusion and indicate the influence of an organic C source. Quartz solubility relations indicate the importance of fluid-flow paths in chemical redistribution during subduction. These results document large-scale fluid flow and the complexity of possible metasomatic and mechanical mixing processes at intermediate levels of subduction zones. The record of subduction-zone mass transfer in the Catalina Schist is compatible with the record inferred for greater depths from geochemical and petrologic studies of arc magmatism.

• OSTI ID: 6159471
• Journal Information: Geology; (USA), Journal Name: Geology; (USA) Vol. 17:11; ISSN GLGYB; ISSN 0091-7613
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
150200* -- Geology & Hydrology of Geothermal Systems
AMPHIBOLITES
CALIFORNIA
CHEMISTRY
COASTAL REGIONS
CRETACEOUS PERIOD
ENERGY SYSTEMS
EVEN-EVEN NUCLEI
FEDERAL REGION IX
FLUID FLOW
FLUIDS
GEOCHEMISTRY
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC HISTORY
GEOTHERMAL SYSTEMS
HYDROTHERMAL ALTERATION
HYDROTHERMAL SYSTEMS
ISLANDS
ISOTOPES
LIGHT NUCLEI
MAGMA
MAGMATISM
MESOZOIC ERA
METAMORPHIC ROCKS
METAMORPHISM
MINERALOGY
NORTH AMERICA
NUCLEI
OXYGEN 18
OXYGEN ISOTOPES
RESERVOIR FLUIDS
ROCKS
SCHISTS
STABLE ISOTOPES
SUBDUCTION ZONES
USA