Al-Mg systematics of hibonite-bearing Ca,Al-rich inclusions from Ningqiang

Details Al-Mg systematics of hibonite-bearing Ca,Al-rich inclusions from Ningqiang Al-Mg systematics of hibonite-bearing Ca,Al-rich inclusions from Ningqiang

May 2011

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011m%26ps...46..719h&link_type=abstract

Meteoritics & Planetary Science, Volume 46, Issue 5, pp. 719-728.

Mathematics

Logic

Scientific paper

Hibonite-bearing Ca,Al-rich inclusions (CAIs) usually occur in CM and CH chondrites and possess petrographic and isotopic characteristics distinctive from other typical CAIs. Despite their highly refractory nature, most hibonite-bearing CAIs have little or no 26Mg excess (the decay product of 26Al), but do show wide variations of Ca and Ti isotopic anomalies. A few spinel-hibonite spherules preserve evidence of live 26Al with an inferred 26Al/27Al close to the canonical value. The bimodal distribution of 26Al abundances in hibonite-bearing CAIs has inspired several interpretations regarding the origin of short-lived nuclides and the evolution of the solar nebula. Herein we show that hibonite-bearing CAIs from Ningqiang, an ungrouped carbonaceous chondrite, also provide evidence for a bimodal distribution of 26Al. Two hibonite aggregates and two hibonite-pyroxene spherules show no 26Mg excesses, corresponding to inferred 26Al/27Al < 8 × 10-6. Two hibonite-melilite spherules are indistinguishable from each other in terms of chemistry and mineralogy but have different Mg isotopic compositions. Hibonite and melilite in one of them display positive 26Mg excesses (up to 25‰) that are correlated with Al/Mg with an inferred 26Al/27Al of (5.5 ± 0.6) × 10-5. The other one contains normal Mg isotopes with an inferred 26Al/27Al < 3.4 × 10-6. Hibonite in a hibonite-spinel fragment displays large 26Mg excesses (up to 38‰) that correlate with Al/Mg, with an inferred 26Al/27Al of (4.5 ± 0.8) × 10-5. Prolonged formation duration and thermal alteration of hibonite-bearing CAIs seem to be inconsistent with petrological and isotopic observations of Ningqiang. Our results support the theory of formation of 26Al-free/poor hibonite-bearing CAIs prior to the injection of 26Al into the solar nebula from a nearby stellar source.

Affiliated with

Also associated with

No associations

Rating

Al-Mg systematics of hibonite-bearing Ca,Al-rich inclusions from Ningqiang does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Al-Mg systematics of hibonite-bearing Ca,Al-rich inclusions from Ningqiang, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Al-Mg systematics of hibonite-bearing Ca,Al-rich inclusions from Ningqiang will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-933420