Integrated investigation of the mixed origin of lunar sample 72161,11 |
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Authors: | Abhijit Basu D. J. Des Marais J. M. Hayes W. G. Meinschein |
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Affiliation: | 1. Dept. of Geology, Indiana University, Bloomington, Ind., USA
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Abstract: | Sample 72161,11 (dark mantle at LRV-3) has a graphic mean grain size (M z) of 3.88 ø, inclusive graphic standard deviation (σ I) of 1.29, and a total carbon content of 204µg C g?1 sample, and is, therefore, quite mature. However, the agglutinate content is only 30% in the 90–177µm particles, indicating an apparent departure from steady state. Analyses of C, CH4, and H2 concentrations in size fractions larger than 149µm show that the volume correlated component of these species increases with increasing grain size. In a homogeneous agglutinate population the volume correlated component is expected to be independent of grain size. The observed increase can be interpreted in terms of the mixing of a dominant local population of coarser agglutinates, with high carbon and hydrogen, with an imported population of finer agglutinates relatively poor in carbon and hydrogen. When analyses of size-fractions from the bulk sample are considered, these effects are apparently obliterated by the admixture of coarse-grained material low in agglutinates. It seems likely that this low agglutinate content is a consequence of the breakdown of the fragile, large agglutinates in the imported material during their movement to the sample site. |
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