ISSN:
1573-0794
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
,
Physics
Notes:
Abstract The rapid increase in the low temperature TL in the first 8 cm of both the Apollo 11 and 12 core tubes illustrates the importance of thermal draining in determining the level of natural TL. We have previously shown that the subsequent decrease in TL at greater depths in the Apollo 12 double core could be attributed in part to a temperature rise because of a positive heat flow. However more refined and detailed measurements reported here show that the TL does not vary monotonically with depth but shows distinct structure. To investigate the nature of this structure we have made measurements on small samples consisting of a few grains each. We find in 14259 and 12033 that only a small fraction of the grains (~1/50) contribute most of the TL. It is also clear that at least two, and possibly more, distinct TL phases are present. The brightest grains frequently contain an AlSiK phase and, less often, a phosphate phase. Still others appear to be a special form of plagioclase. This latter must be relatively rare since most plagioclase grains clearly contribute little TL. Uranium is also found to be associated with P and K bearing grains and it is possible that the radiation responsible for the TL may consist of variable proportions of internal uranium (and thorium) doses mixed with cosmic ray ionization. This could explain the structure. In principle both U rich and U poor thermoluminescing grains can be used independently to study temperature variations in the core.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00561999
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