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Anatomy of individual agglutinates from a lunar highland soil
Author(s) -
BASU Abhijit,
McKAY David S.,
MORRIS Richard V.,
WENTWORTH Susan J.
Publication year - 1996
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/j.1945-5100.1996.tb02112.x
Subject(s) - lunar soil , regolith , weathering , clastic rock , soil water , mineralogy , geology , chemistry , astrobiology , analytical chemistry (journal) , environmental chemistry , geochemistry , soil science , sedimentary rock , physics
— We report results of our investigation of the relationship between values of I s /FeO (relative concentration of nanophase Fe 0 divided by total FeO content), glass abundance, total Fe content, and degree of digestion of <20 μm clasts for 22 individual agglutinates (250–1000 μm) from the mature Apollo 16 soil 61181 (I s /FeO = 82 units in the <250 μm fraction). Agglutinates are important products of space weathering on the Moon, and they influence spectral observations at visible and near‐IR wavelengths. Values of I s /FeO for individual agglutinates (250–1000 μm) within this single soil span a range from 3 to 262 units which is larger than the range observed for all Apollo 16 bulk soils (∼0 to 110 units). No correlation was observed between I s /FeO and glass abundance and FeO concentrations for either agglutinitic glass or whole agglutinate particles under investigation. Our results suggest that the variation in I s /FeO for agglutinates from a single soil may be in part a consequence of natural mixing processes on the Moon that produce highly‐variable environments (with respect to surface exposure) for agglutinate formation and in part to variable kinetics of reactions in an agglutinate melt, which are influenced by a variety of factors including melt composition, temperature, impactor velocity, and quench rate. We cannot exclude but do not see evidence for other processes including addition of exotic agglutinates, micrometeoritic bombardment into compositionally‐diverse microtargets, recycling of agglutinates, preferential melting of very fine soil particles, and production of nanophase Fe 0 in amorphous rims of very fine irradiated lunar grains contributing to the observed variation of I s /FeO.