Physicochemical isotope anomalies

Conference · Wed Jun 01 00:00:00 EDT 1988 · Geochimica et Cosmochimica Acta; (USA)

OSTI ID:5557810

Esat, T M ^[1]

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1. Australian National Univ., Canberra

Isotopic composition of refractory elements can be modified, by physical processes such as distillation and sputtering, in unexpected patterns. Distillation enriches the heavy isotopes in the residue and the light isotopes in the vapor. However, current models appear to be inadequate to describe the detailed mass dependence, in particular for large fractionations. Coarse- and fine-grained inclusions from the Allende meteorite exhibit correlated isotope effects in Mg both as mass-dependent fractionation and residual anomalies. This isotope pattern can be duplicated by high temperature distillation in the laboratory. A ubiquitous property of meteoritic inclusions for Mg as well as for most of the other elements, where measurements exist, is mass-dependent fractionation. In contrast, terrestrial materials such as microtektites, tektite buttons as well as lunar orange and green glass spheres have normal Mg isotopic composition. A subset of interplanetary dust particles labelled as chondritic aggregates exhibit excesses in {sup 26}Mg and deuterium anomalies. Sputtering is expected to be a dominant mechanism in the destruction of grains within interstellar dust clouds. An active proto-sun as well as the present solar-wind and solar-flare flux are of sufficient intensity to sputter significant amounts of material. Laboratory experiments in Mg show widespread isotope effects including residual {sup 26}Mg excesses and mass dependent fractionation. It is possible that the {sup 26}Mg excesses in interplanetary dust is related to sputtering by energetic solar-wind particles. The implication if the laboratory distillation and sputtering effects are discussed and contrasted with the anomalies in meteoritic inclusions the other extraterrestrial materials the authors have access to.

• OSTI ID: 5557810
• Report Number(s): CONF-8703325-; CODEN: GCACA
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Vol. 52:6; Conference: Isotope tracers in geochemistry and geophysics, Pasadena, CA (USA), 23-25 Mar 1987; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CHONDRITES
INCLUSIONS
CHEMICAL COMPOSITION
ISOTOPE RATIO
REFRACTORY METALS
DISTILLATION
GEOCHEMISTRY
GEOLOGIC HISTORY
GEOLOGIC MODELS
MAGNESIUM ISOTOPES
SOLAR FLARES
SOLAR WIND
TEKTITES
ALKALINE EARTH ISOTOPES
ALLOYS
CHEMISTRY
ELEMENTS
ISOTOPES
METALS
METEORITES
SEPARATION PROCESSES
SOLAR ACTIVITY
STONE METEORITES
580400* - Geochemistry- (-1989)