A revised algorithm for calculating TiO₂ from Clementine UVVIS data: A synthesis of rock, soil, and remotely sensed TiO₂ concentrations

Abstract

[1] Investigating mare basalt compositions, at both the sample and remote-sensing level for the Apollo and Luna mare sites, reveals the need for a more complex regression procedure than previously proposed in order to extract accurate TiO 2 concentrations from Clementine spectral reflectance (CSR) data. The TiO 2 algorithm of Lucey and coworkers is modified by using two different sets of regression parameters to relate measured regolith compositions from sampling locations to the CSR properties of these sites. One regression trend fits the majority of Apollo data, and the second regression is a fit to the Apollo 11, Luna 16, and Luna 24 data, which were considered to be anomalous in previous TiO 2 calibrations. These three sites have unusually low albedo compared to other mare landing sites, and some 32% of nearside mare regions appear to share this characteristic. Possible reasons for these differences related to proximity of the other sites to mare-highland boundaries are discussed. Using the dual-regression method, we find (1) that TiO 2 concentrations calculated for the basaltic landing sites faithfully reproduce a bimodal distribution as seen in the sample data, (2) that when coupled with the effects of other thermal neutron absorbers, Ti concentrations are more consistent with observed epithermal-to-thermal neutron-flux ratios than are previous Clementine-based derivations of TiO 2 for basaltic regions, and (3) that basalts of intermediate-TiO 2 concentrations occur most frequently in the Oceanus Procellarum region and that these intermediate concentrations appear to be inherent to the flows underlying the regolith and presumably to the basalt source regions. Citation: Gillis, J. J., B. L. Jolliff, and R. C. Elphic, A revised algorithm for calculating TiO 2 from Clementine UVVIS data: A synthesis of rock, soil, and remotely sensed TiO 2 concentrations,

Volcanic history of the Imbrium basin: A close-up view from the lunar rover Yutu

“…S7). The high-TiO 2 peak is similar to the in situ APXS analyses and the remote sensing results (27,28). The low-TiO 2 tail of the smallest craters is due to excavating the underlying low-Ti basalt unit, as indicated by the low-TiO 2 peak for the larger craters (1-4 km in diameter) and the presence of old low-Ti basalt about 10 km north to the landing site.…”

Stratigraphy and composition of lava flows in Mare Nubium and Mare Cognitum

“…In the following years, many researchers worked on improving and refining the mathematical algorithms (Johnson et al 1985(Johnson et al , 1991Blewett et al 1997;Lucey et al 1998Lucey et al , 2000Gillis and Jolliff 2001;Gillis et al 2003Gillis et al , 2004. Others conducted parallel research on the photometric properties of the Moon's surface (e.g., Fisher and Pieters 1996;Shkuratov et al 1999;Kreslavsky et al 2000) by experimenting on various lunar samples, adding to the work of the Hawai'ian group (Lucey and co-workers).…”

Preliminary results of TiO2 mapping using Imaging Interferometer data from Chang’E-1

“…A series of empirical models have been developed to predict the TiO 2 content from Clementine UVVIS images [29][30][31][32]. Among these models, Lucey's model has been one of the most popular and has undergone a series of refinements [33,34]. Lucey's method introduces a simple relation between the UV/VIS ratio (415 nm/750 nm) and TiO 2 content in soil of a mature mare to a titanium-sensitive parameter θ Ti , an angular measure of the TiO 2 content of soils taken from landing sites and sample stations in the plot of UV/VIS versus visible reflectance, to suppress the effect of maturity [29][30][31][32].…”