Nearly 100 chondrules were extracted from -8.6g of the
Mokoia (CV3) meteorite and have been analyzed by
sequential instrumental neutron activation analysis
(INAA). The resulting data were utilized in a
comprehensive statistical characterization of these
objects and, unlike similar investigations, virtually no
loss of relevant data was incurred due to the use of
inadequate or inappropriate software. Mass and elemental
frequency distributions, correlation analysis and sorting
coefficients support a "nebular" setting for chondrule
genesis, and a scenario in which interstellar "dust-balls"
(= chondrule precursors) are subject to some transient
(short duration) high-energy process(es) followed by
gravitationally or aerodynamically induced sorting, while
it appears that an enhanced oxygen fugacity due to
particle/gas fractionation may also be a factor.
Conversely, a "planetary" setting for chondrule formation
which requires the melting of pre-existing rocks (e.g.,
incompatible with the observed data. Factor analysis has
led to the identification of the following precursor
assemblages (i.e., factors) in the Mokoia chondrite: a
refractory lithophile phase, a siderophile/chalcophile
phase, a Mg-rich (silicate ?) phase, a refractory siderophile phase
and a common lithophile phase.
Previous studies of the Allende (CV3), Ornans (C03),
Semarkona (LL3) and Chainpur (L3) meteorites are compared
with these findings and interchondrite relationships are
discussed (e.g., do these objects share similar parental
materials, or are their compositions somehow
complementary? were they formed in proximity with each
other? etc.). A very unique oxide-sulfide-phosphate
opaque assemblage was found in Mokoia and analyzed by
INAA/electron-probe microanalysis, and may eventually
serve to place constraints on the low-temperature thermal
histories of chondrules or chondrites as well as provide
information concerning the oxygen and sulfur fugacities
within the Mokoia chondrite parent body. / Graduation date: 1991
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/37445 |
| Date | 03 May 1991 |
| Creators | Schilk, Alan J. |
| Contributors | Schmitt, Roman A. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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