Volatile element depletion and 39K/41K fractionation in lunar soils.
Abstract
Evidence for selective loss and isotopic fractionation (in the case of K) of volatile elements during formation of agglutinates by micrometeoritic bombardment of lunar soils is presented. Concentrations and isotopic compositions of volatile elements (K, Rb, Pb) and nonvolatile elements (U, Th, Ba, Sr, rare earths) in separates taken from soils 14163, 14259, 15041, 68501, and 71500 are examined. Rayleigh fractionation calculations applied to K-39/K-41 isotopic data indicate ten-fold recycling of bulk soil, to account for observed isotopic anomalies. The lunar soil fines fraction seems to be a site of deposition for volatile or labile Pb produced during agglutination. Local fines (below 75 microns) are viewed as representative of the parent material for agglutinates formed in situ by micrometeoritic impact. Magnetic separation of agglutinates from soil 68501 revealed a bimodal population, with one class comprising welded blocky magnetic glasses.
- Publication:
-
Lunar and Planetary Science Conference Proceedings
- Pub Date:
- April 1976
- Bibcode:
- 1976LPSC....7..423C
- Keywords:
-
- Chemical Composition;
- Fractionation;
- Lunar Soil;
- Micrometeorites;
- Potassium Isotopes;
- Trace Elements;
- Abundance;
- Meteorite Collisions;
- Volatility;
- Lunar and Planetary Exploration