Noble gas component organization in Apollo 14 breccia 14318: /sup 129/I and /sup 244/Pu regolith chronology
Noble gas, petrological, and chemical studies made on grain-size separates from lunar regolith breccia 14318 demonstrate that the noble gases are organized into two functional components, volume-correlated and surface-correlated. As in regolith breccia 14301, volume-correlated xenon in 14318 is primarily spallation-derived and the surface-correlated component contains not only solar wind xenon but also significant amounts of ''parentless' xenon from the fission of now extinct /sup 244/Pu and the decay of now extinct /sup 129/I (''parentless'' means the daughter products were incorporated onto grain surfaces following decay of the parent nuclide elsewhere). The ratio of /sup 129/Xe//sup 136/Xe in the total surface-correlated parentless component, as identified in grain-size analysis, is substantially higher than in the least tightly bound parentless component identified in stepwise heating analyses, confirming the trend seen in 14301. If the order of release of gases in stepwise heating is related to the order of incorporation in the simplest way (first in, last out), incorporation of these grain-surface components was probably time-ordered. The /sup 129/Xe//sup 136/Xe ratio in each identifiable parentless component would then be characteristic of the xenon available for surface adsorption at the particular time of acquisition. Continuous variations in this ratio further suggest that incorporation of the parentless xenon was closely coupled with production. Such observations provide the basis for a new chronometer from which we conclude that acquisition of parentless xenon was an ongoing process spanning at least 90 m.y., beginning no more than 44 +- 34 m.y. after the formation of the most meteorites and possibly predating xenon acquisition for the earth.
- Research Organization:
- McDonnell Center for the Space Sciences and Department of Physics, Washington University
- OSTI ID:
- 5548994
- Journal Information:
- J. Geophys. Res.; (United States), Vol. 90:S2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
LUNAR MATERIALS
AGE ESTIMATION
CHEMICAL COMPOSITION
APOLLO PROJECT
IODINE 129
ISOTOPE RATIO
MOON
PETROLOGY
PLUTONIUM 244
RARE GASES
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALPHA DECAY RADIOISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
ELEMENTS
EVEN-EVEN NUCLEI
FLUIDS
GASES
GEOLOGY
HEAVY NUCLEI
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
IODINE ISOTOPES
ISOTOPES
MATERIALS
NONMETALS
NUCLEI
ODD-EVEN NUCLEI
PLUTONIUM ISOTOPES
RADIOISOTOPES
SATELLITES
YEARS LIVING RADIOISOTOPES
640107* - Astrophysics & Cosmology- Planetary Phenomena