Computer Science
Scientific paper
Mar 2007
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007gecoa..71.1624l&link_type=abstract
Geochimica et Cosmochimica Acta, Volume 71, Issue 6, p. 1624-1635.
Computer Science
4
Scientific paper
We have studied lunar impact spherules from the Apollo 12 and Apollo 14 landing sites, examining the isotopic composition of argon released by stepwise heating. Elsewhere, we reported the formation ages of these spherules, determined by the 40Ar/39Ar isochron method. Here, we discuss solar and cosmogenic argon from the same spherules, separating these two components by correlating their partial releases with the releases of calcium-derived 37Ar on a “cosmochron” diagram. We use the abundances of cosmogenic argon to derive a cosmic ray exposure age for each spherule, and demonstrate that single scoops of lunar soil contain spherules which have experienced very different histories of exposure and burial. The solar argon is seen to be separated into isotopically lighter and heavier fractions, which presumably were implanted to different depths in the spherules. The abundance of the isotopically heavy solar argon is too great to explain as a minor constituent of the solar particle flux, such as the suprathermal tail of the solar wind. The fact that the spherules have been individually dated allows us to look for possible variations in the solar wind as a function of time, over the history of the Solar System. However, the isotopic composition and fluence of solar argon preserved in the lunar spherules appear to be independent of formation age. We believe that most of the spherules are saturated with solar argon, having reached a condition in which implantation by the solar wind is offset by losses from solar-wind sputtering and diffusion.
Levine Jonathan
Muller Richard A.
Renne Paul R.
No associations
LandOfFree
Solar and cosmogenic argon in dated lunar impact spherules 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 Solar and cosmogenic argon in dated lunar impact spherules, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Solar and cosmogenic argon in dated lunar impact spherules will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-861035