Constraining the source regions of lunar meteorites using orbital geochemical data

A Calzada‐Diaz,I A Crawford,T A Nordheim,K H Joy

doi:10.1111/maps.12412

Abstract

AbstractLunar meteorites provide important new samples of the Moon remote from regions visited by the Apollo and Luna sample return missions. Petrologic and geochemical analysis of these meteorites, combined with orbital remote sensing measurements, have enabled additional discoveries about the composition and age of the lunar surface on a global scale. However, the interpretation of these samples is limited by the fact that we do not know the source region of any individual lunar meteorite. Here, we investigate the link between meteorite and source region on the Moon using the Lunar Prospector gamma ray spectrometer remote sensing data set for the elements Fe, Ti, and Th. The approach has been validated using Apollo and Luna bulk regolith samples, and we have applied it to 48 meteorites excluding paired stones. Our approach is able broadly to differentiate the best compositional matches as potential regions of origin for the various classes of lunar meteorites. Basaltic and intermediate Fe regolith breccia meteorites are found to have the best constrained potential launch sites, with some impact breccias and pristine mare basalts also having reasonably well‐defined potential source regions. Launch areas for highland feldspathic meteorites are much less well constrained and the addition of another element, such as Mg, will probably be required to identify potential source regions for these.

Highlights

The Moon provides valuable information to understand the early history of the solar system as it preserves the geological record of the processes that have shaped the formation and evolution of the Earth–Moon system
Our results indicate that the highlands in the vicinity of the John Herschel crater and Mons Caucasus in the north and east of the Procellarum KREEP Terrain (PKT) are the most probable sources of these meteorites (Fig. 4)
Our results show that this meteorite was likely launched from the farside Feldspathic Highland Terrane (FHT); Fig. 6

Summary

Introduction

The Moon provides valuable information to understand the early history of the solar system as it preserves the geological record of the processes that have shaped the formation and evolution of the Earth–Moon system. It is the only planetary body from which samples have been returned (382 kg returned by the Apollo and Luna 16, 20, and 24 missions), and these have shed considerable light on the age and composition on the Moon (see Vaniman et al 1991; Shearer et al 2006; Jaumann et al [2012] for comprehensive reviews).

Methods

Discussion

Conclusion