HR: 09:00h
AN: P11A-05    [PDF]
TI: Testing the Relationship Between UV-VIS Color and TiO$_{2}$ Content in the Lunar Maria.
AU: * Gillis, J J
EM: gillis@higp.hawaii.edu
AF: Hawaii Institute of Geophysics and Planetology, University of Hawaii, 1680 East-West Road, POST 504, Honolulu, HI 96822 United States
AU: Lucey, P G
AF: Hawaii Institute of Geophysics and Planetology, University of Hawaii, 1680 East-West Road, POST 504, Honolulu, HI 96822 United States
AB: Remotely sensed data are used to classify the lunar maria on the basis of "color"; where mature maria with steep UV-VIS continuum slopes are defined as "red", and those with relatively flatter continuum slopes are termed "blue". The canonical view is that large apparent color variations are due to TiO$_{2}$ concentration, as TiO$_{2}$ is the primary variable in lunar basalts, ranging from $<$1 wt.% to $>$14 wt.% TiO$_{2}$. This interpretation was based on the observation of compositional and color extremes juxtaposed in Mare Serenitatis and Tranquillitatis. Lunar Prospector (LP) data allows direct testing of the assumption of the control of lunar UVVIS color by TiO$_{2}$ in the mare. We compare LP gamma-ray (GRS) and neutron spectrometer (NS) data for TiO$_{2}$ with Clementine Spectral Reflectance (CSR) data in order to examine basalts with a full range of TiO$_{2}$ concentrations. Areas were selected on the basis of uniform color over 2-degree areas, to match the resolution of the LPGRS data. First we conducted a comparison between LP-GRS and LP-NS data. This comparison yields an approximate two-to-one correlation (the NS data exhibiting higher values), a significant amount of scatter (R2 = 0.63), and an offset +1.7 TiO$_{2}$ NS data. This is an important observation as it shows that even direct measurements of surface TiO$_{2}$ contain considerable uncertainty, even for the best possible scenario for determining TiO$_{2}$ contents in the maria. A comparison of LPGRS TiO$_{2}$ and CSR color data yields a poor correlation (R2 = 0.53), that is, UV-VIS color is a poor predictor of LPGRS TiO$_{2}$ in mature mare. A comparison of LPNS and CSR color data, however, yields a better correlation (R2 = 0.85). On the basis of this preliminary analysis, we conclude that TiO$_{2}$ controls UVVIS color in the mare. However, we will continue this analysis at the higher resolution accessible to LPNS data to further explore the correlation between data sets. We will present an empirical model that uses a relationship between LPNS and CSR UV-VIS data to predict TiO$_{2}$ contents globally and at full Clementine resolution (250 m/pixel).
DE: 5400 PLANETOLOGY: SOLID SURFACE PLANETS
DE: 5410 Composition
DE: 5464 Remote sensing
DE: 5480 Volcanism (8450)
DE: 5494 Instruments and techniques
SC: Planetary Sciences [P]
MN: 2003 Fall Meeting