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The petrology of meteoritic chrondrules: Evidence for fluctuation conditions in the solar nebula

Thesis/Dissertation ·
OSTI ID:6514762
A detailed petrologic study of magnesian chondrules in CM2, CR2, CO3, CV3, and UOC (LL3,L3,H3) primitive chondrites has been made to establish how chondrules formed and evolved in the solar nebula. The compositions of mineral constituents associated with magnesian chondrules have been used to calculate the redox conditions of the zones in the solar nebular where these chondrules formed. The compositions of these mineral constituents are evidence for non-solar compositions, particularly non-solar O/H and O/C, in the nebula. The data suggest that these element ratios fluctuated with space and/or time in the zones where C3 and UOC chondrules formed. Furthermore, it appears that UOC chondrules, in general, formed in a zone with greater OH than that in the zone where C3 chondrules formed; and C3 chondrules formed in a zone with greater O/H than that where C2 chondrules formed. Non-solar redox conditions in the solar nebula have been attributed to processes that concentrate dust relative to gas. When concentrations of dust, which consists of oxides, are heated and vaporized, non-solar oxygen-rich gas is produced. The effects of the concentration, vaporization, and recondensation of dust in the nebula on oxygen isotopic systematics have been modelled. It is proposed that chondrules formed by the melting of this mass-fractionated dust, whose isotopic composition was retained by the chondrules.
Research Organization:
Harvard Univ., Boston, MA (USA)
OSTI ID:
6514762
Country of Publication:
United States
Language:
English