Much of our quantitative understanding of the impact history of the inner solar system derives from 40AR/39AR geochronology of lunar impact melt materials in returned samples and meteorites. Most…

This is a $381,274 grant awarded by NASA to Arizona State University (ASU) to conduct a multifaceted study of lunar meteorites using incremental heating and ultraviolet laser ablation microprobe (UVLAMP) 40Ar/39Ar geochronology. The goal is to improve the understanding of the lunar impact history, which is a high priority for NASA's solar system research program. This will be the first extensive UVLAMP study of lunar meteorite samples, which can provide valuable age information to complement previous studies of Apollo mission samples. The grant does not have a set-aside designation. As a comprehensive public research university, ASU has a long history of conducting scientific research and providing professional services to federal agencies through both prime contracts and subcontracts.

Much of our quantitative understanding of the impact history of the inner solar system derives from 40AR/39AR geochronology of lunar impact melt materials in returned samples and meteorites. Most published dates were obtained through incremental heating experiments performed on polymineralic (or minerals + melt) rock fragments of such material. Unfortunately, the interpretation of age spectra produced from such experiments is not always straightforward. IT has been shown recently that 40AR/39AR ultraviolet laser ablation microprobe (uvlamp) studies of complex impact melt breccias (imbs) with high spatial resolution can provide valuable age information and aid in the interpretation of incremental heating datasets. Thus far, all uvlamp 40AR/39AR studies of imbs.have focused on samples returned by the apollo missions. However, older incremental heating datasets for similar lithologies in lunar meteorites suggest that the studies of these materials may substantially improve our understanding of the lunar impact record.here we propose an intensive, multifaceted incremental heating and uvlamp study of lunar meteorites with the goal of better understanding the impact history of the moon. This will be the first extensive uvlamp 40AR/39AR microanalytical study of lunar meteorite samples. By applying this technique, we hope to reduced ambiguities in the age interpretation of incremental heating.datasets and achieve a more robust understanding of impact melting events recorded by lunar meteorites importantly, this study augments previous 40AR/39AR studies of lunar impact melt materials in the apollo archive. Because the apollo samples were collected in a geographically restricted region of the moon, our community perspective of the impact history way be strongly biased by impact materials derived from a few large, nearby impacts. A more comprehensive sense of the impact history of the moon requires a broader sampling of materials from other parts of the moon. Until such materials are returned by future exploration missions, the study of.lunar meteorites is our most effective way to limit bias in our understanding of lunar impact chronology. Such understanding is a high priority goal for NASA-supported lunar science, and directly relevant to the goals of the solar system workings program.