Presolar isotopic and chemical signatures in hibonite-bearing refractory inclusions from the Murchison carbonaceous chondrite
- Washington Univ., St. Louis, MO (USA)
Magnesium-, calcium-, and titanium-isotopic compositions, as well as trace-element abundances, have been determined by ion microprobe mass spectrometry for 37 hibonite-bearing inclusions from the Murchison carbonaceous chondrite. These and previously analyzed hibonite-bearing inclusions can be divided into three main groups based on morphological and mineralogical criteria. Within the morphological groups of hibonite-bearing inclusions, a few have exceptional chemical and isotopic characteristics such as SHIB spherule 7-170. However, independent of the morphological groups, there are correlations in hibonite isotopic systematics and chemistry that hold for all inclusions studied: (1) no inclusion has both a large {sup 50}Ti anomaly and {sup 26}Mg*; and (2) inclusions depleted in the ultrarefractory elements have {sup 26}Mg*, with the exception of those which have a large {sup 50}Ti anomaly. These features clearly establish a relationship between chemical and isotopic characteristics of the inclusions which must predate their formation. Several components were combined, probably as mixtures of dust grains or crystals, and were melted to form refractory inclusions. The nucleosynthetic anomalies must be inherited from stellar environments; it is possible that the depletion in ultrarefractory elements are also a memory of stellar condensation and are not necessarily related to a condensation event in the solar nebula as has generally been assumed.
- OSTI ID:
- 6106041
- Journal Information:
- Geochimica et Cosmochimica Acta; (USA), Vol. 54:11; ISSN 0016-7037
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CHONDRITES
CHEMICAL COMPOSITION
ISOTOPE DATING
PETROGENESIS
CALCIUM ISOTOPES
COSMOLOGICAL MODELS
GEOCHEMISTRY
GEOLOGIC HISTORY
INCLUSIONS
ION MICROPROBE ANALYSIS
ISOTOPE RATIO
MAGNESIUM ISOTOPES
MINERALOGY
ORIGIN
PETROCHEMISTRY
TITANIUM ISOTOPES
AGE ESTIMATION
ALKALINE EARTH ISOTOPES
CHEMICAL ANALYSIS
CHEMISTRY
ISOTOPES
MATHEMATICAL MODELS
METEORITES
MICROANALYSIS
NONDESTRUCTIVE ANALYSIS
STONE METEORITES
580000* - Geosciences