Water Content, Chlorine and Hydrogen Isotope Compositions of Lunar Apatite

Abstract

The Moon has been thought to have a bulk planetary water content < 1 ppb [1]. Recent ion microprobe analyses have shown that lunar samples contain up to 7000±1000 ppm OR (reported as equivalent H_20) in apatite and 4-46 ppm in igneous glass [2-6]. These studies suggest that the mantle sources of at least some lunar magmas contain from 64 ppb to 200 ppm [4-6]. Sharp et al. [6] report an apparently contradictory observation -that ^(37)Cl values of lunar samples vary from -1 to 24%o, with an upper extreme they argue demands devolatilization of anhydrous melts. We examine this issue further through measurements of water content, δ^(37)Cl, and δD of apatite from lunar meteorites MIL 05035, NWA 2977, and Dhofar 458.

Files

Additional details