A negative Ce anomaly in a peridotite xenolith: Evidence for crustal recycling into the mantle or mantle metasomatism

Journal Article · Mon May 01 00:00:00 EDT 1989 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(89)90208-1· OSTI ID:5022983

Neal, C R; Taylor, L A ^[1]

---

1. Univ. of Tennessee, Knoxville (USA)

The presence of negative cerium anomalies in island arc lavas has been considered enigmatic. Such negative Ce anomalies must be inherent in the source region and can be produced by subducting pelagic sediments + seawater-altered basalts (SWAB) into the mantle. A mantle peridotite from the Malaitan alnoeite also contains a negative Ce anomaly, which can be produced by sediment recycling into the upper mantle. However, in spite of the poorly defined effects of cryptic metasomatism and associated fO{sub 2} conditions, such a process also seems plausible for the generation of negative Ce anomalies. In order to define the petrogenesis of this peridotite within the constraints of the present experimental data, the authors have attempted various mixing models with the end-members: mantle peridotite, Pacific sediment and seawater-altered basalt. In their model, it was assumed that negative Ce anomalies cannot be produced by magmatic or metasomatic processes. Best results were obtained from mixing a maximum of 3 to 5% seawater-altered basalt and 2 to 3% pelagic sediment, with a LREE-enriched mantle precursor. The authors' model stresses the importance of the contribution that recycled crustal materials can have on the composition of the upper mantle, in particular the recognition of a crustal signature in a mantle regime.

• OSTI ID: 5022983
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Vol. 53:5; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
OCEANIC CRUST
METAMORPHISM
PERIDOTITES
CHEMICAL COMPOSITION
PETROGENESIS
BASALT
CERIUM
EARTH MANTLE
GEOCHEMISTRY
GEOLOGIC MODELS
HYDROTHERMAL ALTERATION
LAVA
MAGMA
SEDIMENTS
CHEMISTRY
EARTH CRUST
ELEMENTS
IGNEOUS ROCKS
METALS
PLUTONIC ROCKS
RARE EARTHS
ROCKS
VOLCANIC ROCKS
580000* - Geosciences