Trace element and isotopic characteristics of western Pacific pelagic sediments: Implications for the petrogenesis of Mariana arc magmas

Journal Article · Wed Apr 01 04:00:00 EST 1992 · Geochimica et Cosmochimica Acta; (United States)

OSTI ID:5263250

Lin, Pingnan ^[1]

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1. Ohio State Univ., Columbus (United States)

Rare earth element (REE) and Ned isotopic data for ten representative samples of Lower Cretaceous to Miocene pelagic sediments from the western Pacific indicate a wide range of compositions for sediments being subducted beneath the mariana and Volcano arcs. All samples are enriched in light rare earth elements (LREEs) and show negative Eu and Ce anomalies. The values of {epsilon}{sub Nd} range from +0.6 to {minus}7.3. These data are used to calculate the Bulk Western Pacific Sediment (BWPS), which is characterized by low Sr/Nd (10), Ba/La (13), and {epsilon}{sub Nd} ({minus}5.2) and high {sup 87}Sr/{sup 86}Sr (0.7078) compared to that of Mariana and Volcano arc lavas. This composite sediment is used to refine a mixing model for the origin of Mariana and Volcano arc melts. Some lavas from the northern Mariana Arc have Ba/La higher than that of BWPS, which indicates that a third component is required. The high Ba/La in the mantle source for these lavas is interpreted to result from multiple episodes of fluid fractionation. The mixing model indicates that a minor amount of sediment and a low proportion of metasomatic fluid fluxes the mantle source at a late stage when the subarc mantle is already highly metasomatized. This model also suggests that the mantle source for arc melts is affected more by metasomatic fluids than by melting or bulk mixing of sediments.

• OSTI ID: 5263250
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Journal Name: Geochimica et Cosmochimica Acta; (United States) Vol. 56:4; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ALKALINE EARTH ISOTOPES
CENOZOIC ERA
CHEMICAL COMPOSITION
CHEMISTRY
COMPARATIVE EVALUATIONS
CRETACEOUS PERIOD
EARTH CRUST
EARTH MANTLE
ELEMENTS
EVALUATION
GEOCHEMISTRY
GEOLOGIC AGES
GEOLOGIC MODELS
IGNEOUS ROCKS
ISOTOPE RATIO
ISOTOPES
LAVA
MAGMATISM
MESOZOIC ERA
METALS
MIXING
NEODYMIUM ISOTOPES
OCEANIC CRUST
PACIFIC OCEAN
PETROGENESIS
RARE EARTHS
ROCKS
SEAS
SEDIMENTS
STRONTIUM ISOTOPES
SUBDUCTION ZONES
SURFACE WATERS
TERTIARY PERIOD
TRACE AMOUNTS
VOLCANIC ROCKS