Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8906777 | Earth and Planetary Science Letters | 2018 | 10 Pages |
Abstract
We propose that porphyritic chondrules formed during gas-assisted melting of nebular condensates comprising relict olivine grains with varying Î17O values and Ca-Al-Ti-rich minerals such as those observed within amoeboid olivine aggregates. Incomplete melting of chondrule precursors produced Ca-Al-Ti-rich melts (CAT-melts), allowing subsequent crystallization of Ca-Al-Ti-rich host olivine crystals via epitaxial growth on relict olivine grains. Incoming MgO and SiO from the gas phase induced (i) the dilution of CAT-melts, as attested by the positive Al-Ti correlation observed in chondrule olivine crystals, and (ii) buffering of the O-isotope compositions of chondrules, as recorded by the constant Î17O values of host olivine grains. The O-isotopic compositions of host olivine grains are chondrule-specific, suggesting that chondrules formed in an array of environments of the protoplanetary disk with different Î17O values, possibly due to variable solid/gas mixing ratios.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Earth and Planetary Sciences (General)
Authors
Yves Marrocchi, Johan Villeneuve, Valentina Batanova, Laurette Piani, Emmanuel Jacquet,