Titanium isotopic anomalies in chondrules from carbonaceous chondrites

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

DOI:https://doi.org/10.1016/0016-7037(88)90086-5· OSTI ID:5100445

Niemeyer, S

Isotopic analyses of Ti from chondrules of carbonaceous chondrites reveal that Ti anomalies are present; anomalies are detected only at /sup 50/Ti. For a suite of eight Allende chondrules, four give well-resolved anomalies which range from a /sup 50/Ti deficit of two epsilon-units to a /sup 50/Ti excess of nine epsilon-units. No clear link is evident between the structure or composition of the chondrules and the Ti anomalies. However, the chondrule with by far the largest Ti isotopic anomaly is also Al-rich. Yet the absence of a strict correlation between the Ca, Al, and Ti contents and the Ti anomalies, together with the similarity of the /sup 50/Ti excess for the one chondrule to that of most Ca-Al-rich inclusions (CAIs), indicate that the relation between degree of refractory enrichment and the magnitude of Ti isotopic anomalies is not a simple one. Single chondrules from Murchison, Kaidun, and Kakangari all fail to exhibit a well-resolved anomaly, although in the latter two the single analysis of each precludes resolving anomalies of less than three epsilon-units. These observations support the view that the Ti isotopic diversity in chondrules in an inherited feature from their precursor assemblages of dust. Models which envision similar precursors for both chondrules and matrix are consistent with the Ti isotopic data. But at least two distinct solid-matter reservoirs are required for the Allende chondrules alone, which underscores the diversity in the nebular dust. These Ti anomalies also caution that more than one dust isotopic component may be necessary to account fully for the oxygen isotopic variations in chondrules. The Ti anomalies in chondrules argue strongly against models which ascribe the Ti anomalies in CAIs to unique features of their evolution; instead, heterogeneities were more common in the nebular dust.

• Research Organization: Lawrence Livermore National Lab., CA (USA)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5100445
• Journal Information: Geochim. Cosmochim. Acta; (United States), Vol. 52:2
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CHONDRITES
INCLUSIONS
QUANTITATIVE CHEMICAL ANALYSIS
TITANIUM ISOTOPES
ISOTOPE RATIO
MOLECULAR MODELS
ALUMINIUM
CALCIUM
ORIGIN
TITANIUM
ALKALINE EARTH METALS
CHEMICAL ANALYSIS
ELEMENTS
ISOTOPES
MATHEMATICAL MODELS
METALS
METEORITES
STONE METEORITES
TRANSITION ELEMENTS
580400* - Geochemistry- (-1989)