On Pu-244 in lunar rocks from Fra Mauro and implications regarding their origin.

The evidence for in situ produced fission xenon from Pu-244 in rock 14321 is presented. The inferred abundance ratio Pu-244/U-238 is found to be consistent with values observed in a meteorite. Data from a stepwise release of the xenon permits a characterization of the trapped component, which can be shown to be distinct from solar xenon. We discuss the evidence for the presence of fission gases and of uncorrelated radiogenic argon in this and in other Apollo 14 rocks and some implications regarding their origin.