Lunar Geology Survey With Remote Sensing And Apollo Samples

Abstract

In this dissertation, I analyze the mineralogy of lunar soil and core samples with spectroscopy. Using these sample data as ground truth, I study the global mineral abundances and Mg# (molar Mg/(Mg+Fe)) distribution through radiative transfermodeling and remotely sensed images. In Chapter 2, I study the major compositional classes of Apollo 15, 16 and 17 samples from the glass-free mineral modes derived by X-ray diffraction (XRD). Using sample data as ground truth, we mapped the global compositional class distributions, and our results suggest that both the lunar highlands and South Pole-Aitken (SPA) basin are enriched with noritic materials. I propose a "two mantles" hypothesis: The noritic composition in highland and SPA basin revealed an low-Ca pyroxene (LCP) rich upper mantle (low in Mg#) that existed before the mantle overturn; while the olivine-rich basin rings trapped the post-overturn upper mantle (high in Mg#). In Chapter 3, I present a model that can unmix mineral abundance and chemistry based on radiative transfer theory. A new set of optical constants for olivine, orthopyroxene and clinopyroxene is reported. I build a spectral library containing mineral mixtures of plagioclase, olivine, low-Ca pyroxene and high-Ca pyroxene and Mg# ranging within 40-90.The accuracy of our model is <3 vol% for olivine, low-Ca pyroxene and high-Ca pyroxene, <6 vol% for plagioclase, and <10 for Mg#. A global Mg# map is produced using our model and the Moon Mineralogy Mapper data, and the Mg# value is consistent with results from Lunar Prospector gamma-ray spectrometer. In Chapter 4, I present the preliminary results of the multiband images and hyperspectral measurements for the first dissection of core 73002. Both multiband images and hyperspectral data show systematic darkening and reddening from bottom to top of the core, indicating an increasing maturity from subsurface to surface soils. FeO and TiO2 abundances suggest the soils within the core have homogeneous compositions, suggesting little contamination from lateral mixing. An optical maturity profile along the core suggests the local vertical regolith reworking depth is about 14 cm, corresponding to a time range around 61 million years. During this time, maturity of surface soils changed from immature to submature.