Geochemical and isotopic characteristics of lithospheric mantle beneath West Kettle River, British Columbia: Evidence from ultramafic xenoliths

Journal Article · Mon Sep 10 04:00:00 EDT 1990 · Journal of Geophysical Research; (USA)

DOI:https://doi.org/10.1029/JB095iB10p15879· OSTI ID:6055754

Xue, Xianyu; Baadsgaard, H; Scarfe, C M ^[1]; Irving, A J ^[2]

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1. Univ. of Alberta, Edmonton (Canada)
2. Univ. of Washington, Seattle (USA)

A group of spinel peridotite xenoliths from West Kettle River, British Columbia, represents essentially undepleted to moderately depleted lithospheric mantle rocks in terms of major and compatible trace elements. Whole rock Sr isotopic composition for most of these xenoliths, and whole rock Sm-Nd isotopic composition and LREE contents for some of them, seem to have been perturbed by near-surface processes. Sr and Nd isotopic results for acid-cleaned clinopyroxenes separated from these spinel peridotites reveal an isotopically mid-ocean ridge basalt (MORB)-like mantle. Seven spinel lherzolites gave Nd model ages of 1.5-3.6 Ga, similar to MORB, and on a Sm-Nd isotope diagram plot close to a reference Nd isochron with an age of 0.7 Ga and an initial {var epsilon}{sub Nd} of +7. These features likely resulted from multiple mantle depletion. The isotopic similarities of these xenoliths with MORB suggest that this area is underlain by oceanic lithospheric mantle, possibly accreted to North America during the mid-Jurassic. The Nd isochron age could record the time when the oceanic lithosphere was isolated from the asthenosphere. Recent enrichment event may have acted on such a depleted mantle, as indicated by the low Sm/Nd ratios of two spinel harzburgites.

• OSTI ID: 6055754
• Journal Information: Journal of Geophysical Research; (USA), Journal Name: Journal of Geophysical Research; (USA) Vol. 95:B10; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
AGE ESTIMATION
ALKALINE EARTH ISOTOPES
BASALT
BRITISH COLUMBIA
CANADA
CHEMICAL ANALYSIS
CHEMISTRY
EARTH CRUST
EARTH MANTLE
ELEMENTS
GEOCHEMISTRY
GEOLOGIC FORMATIONS
IGNEOUS ROCKS
ISOTOPE RATIO
ISOTOPES
METALS
MINERALS
NEODYMIUM ISOTOPES
NORTH AMERICA
OCEANIC CRUST
OXYGEN COMPOUNDS
PERIDOTITES
PLUTONIC ROCKS
PYROXENES
RARE EARTH ISOTOPES
RARE EARTHS
ROCKS
SAMARIUM ISOTOPES
SILICATES
SILICON COMPOUNDS
STRONTIUM ISOTOPES
TRACE AMOUNTS
VOLCANIC ROCKS