Mantle metasomatism beneath western Victoria, Australia. II. Isotopic geochemistry of Cr-diopside lherzolites and Al-augite pyroxenites

Journal Article · Mon Feb 01 00:00:00 EST 1988 · Geochim. Cosmochim. Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(88)90100-7· OSTI ID:5065224

Griffin, W L; O'Reilly, S Y; Stabel, A

Cr-diopside spinel lherzolite xenoliths from Victoria show metasomatic introduction of amphibole +- mica +- apatite, accompanied by enrichments in Sr, LREE and other incompatible elements. The metasomatism can be related to fluids emanating from crystallizing basaltic magmas now represented by dykes of pyroxenite. Abundant garnet and spinel metapyroxenites are products of an older magmatic episode; igneous-textured wehrlite series xenoliths represent a younger (Recent.) episode. Sr-Nd isotopic compositions of the lherzolites spread into the enriched mantle field (epsilon/sub Nd/ < O, epsilon /sub Sr/ > O). Nd isotopic systematics suggest a maximum age for LREE enrichment of <700 Ma at 300-500 Ma, the metapyroxenites define a mixing hyperbola with the lherzolites, most of which have epsilon/sub Sr/ > O at this time. More detailed mixing models require a third (apatite-rich component with present-day epsilon/sub Sr/ and epsilon/sub Nd/ approx. O). The least-modified metapyroxenites have very unradiogenic Nd and unsupported radiogenic Sr, suggesting a large component of older recycled crustal material. The origin of the apatite component is uncertain.

• Research Organization: Mineralogisk-Geologisk Museum, Oslo (Norway)
• OSTI ID: 5065224
• Journal Information: Geochim. Cosmochim. Acta; (United States), Vol. 52:2
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
VICTORIA
EARTH MANTLE
GEOLOGIC DEPOSITS
VOLCANIC ROCKS
CHEMICAL COMPOSITION
GEOCHEMISTRY
HYDROTHERMAL ALTERATION
QUANTITATIVE CHEMICAL ANALYSIS
ALUMINIUM
APATITES
BASALT
CHROMIUM
DIOPSIDE
GEOLOGIC MODELS
GEOTHERMAL FLUIDS
INCLUSIONS
ISOTOPE RATIO
MAGMA
SPINELS
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
AUSTRALASIA
AUSTRALIA
CHALCOGENIDES
CHEMICAL ANALYSIS
CHEMISTRY
ELEMENTS
FLUIDS
IGNEOUS ROCKS
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
METALS
MINERALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PHOSPHATE MINERALS
PYROXENES
ROCKS
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
TRANSITION ELEMENTS
580400* - Geochemistry- (-1989)