Hydrogen, oxygen and silicon isotope systematics in lunar material

This paper reviews studies of the abundances of hydrogen, oxygen and silicon isotopes in lunar material which have been published between 1970 and 1975. A few unpublished oxygen isotope data for Luna 16 and 20 soils are also briefly discussed. Attention is directed mainly to the isotopic evidence relating to; the origin of the water in lunar material, the large variations in oxygen and silicon isotope abundances found associated with the surfaces of grains from the regolith, the temperatures recorded in the crystalline rocks by the partition of 18O between coexisting phases, and the origin of the Moon. It is concluded that; the bulk of the hydrogen in the lunar soils represents protons implanted from the solar wind and is essentially deuterium free, rarely samples of relatively deuterium rich hydrogen are found probably resulting from in situ spallation reactions, the water found in lunar samples is probably entirely terrestrial contamination, extreme 18O and 30Si enrichments are found in the surfaces of grains in the lunar soil, oxygen isotope isothermometry on lunar basalts gives temperatures in the approximate range 1000 to 11500C generally close to experimentally determined liquidus temperatures, and recent oxygen isotope studies provide exciting new evidence that the Earth-Moon system has a different origin from the higher temperature condensates in the chondritic meteorites. (U.K.)