Chronology of Accessory Phases in Lunar Meteorite Northwest Africa 12593

Lunar meteorites are complementary to the suite of rock and regolith samples collected by the Apollo missions. While the Apollo samples represent
the most pristine material we have from the Moon, lunar meteorites represent a more global sampling of the lunar crust, albeit without geologic context [e.g. 1]. As such, lunar meteorites are important for understanding the composition of the lunar crust and the processes responsible for its formation and evolution.

This work aims to understand the observed differences in accessory phase chronology and volatile chemistry between lunar meteorites and Apollo rocks. For example, apatite ages in Apollo samples range from ~3.83 to 4.28 Ga [e.g. 2, 3], while apatites in lunar meteorites range from ~3.00 to 4.44 Ga [e.g. 4, 5]. Additionally, a much larger range of Cl isotope compositions and concentrations is observed in lunar meteorites as compared to Apollo samples[e.g. 6]. It has recently been shown that impact metamorphism can influence both chronology and chemistry of phosphates [e.g. 7, 8].

Here we present the first chronologic results from a consortium study pairing chronology, volatile chemistry, and crystal structure of apatites in a lunar
breccia meteorite. The results of this work will help inform interpretation of ongoing analyses of apatites separated from Apollo soils.

Note: Extended abstract on document.