Quantitative Characterization of Lunar Mare Orientale Basalts Detected by Moon Mineralogical Mapper on Chandrayaan-1 - Planetary Exploration and Science: Recent Results and Advances - page 29

plagioclase and clinopyroxene and the dominant rock types in this region are
gabbroic anorthosite and anorthosite gabbro. These results have been validated
through spectral mixing and unmixing through the available Apollo sample data.

2.3.1.3 TiO 2 Estimation

High-Ti mare soils are attractive resources for lunar liquid oxygen (LLOX) pro-
duction because of their unconsolidated nature, high ilmenite abundance, and
widespread occurrence (Chambers et al. 1995 ). There is much debate over whether
to use mare soils or basalts as raw materials for mineral extraction, especially
ilmenite (Heiken and Vaniman 1990 ;TaylorandMcKay 1992 ). Ilmenite abundance
in mare basalts and soils are an important resource in the lunar exploration projects.
Chemically, mare basalts can be divided into two broad groups: (1) the older high-
Ti group (age 3,550-3,850 Ma, TiO 2 content 9-13 %) and (2) the younger, low-Ti
group (age 3,150-3,450 Ma, TiO 2 content 1-5 %). Experimental studies show that,
the low-Ti basalts could have been derived from an olivine-pyroxene source rock
at depths ranging from 200 to 500 km, while the high-Ti basalts could have been
derived from olivine-pyroxene-ilmenite cumulates in the outer 150 km of the Moon
(Papike et al. 1976 ).
The following algorithm derived by Lucey et al ( 1998 ) for estimation of TiO 2
weight percentage is used:
Ti D arctan .R 415 =R 750 / 0:45
R 750 0:05

(2.1)

TiO 2 D Ti 20:79 . Ti 22:928/ C 5:909

(2.2)

Based on this analysis, it is observed that the percentage of TiO 2 weight in most
of the Orientale basin basalts never varies more than 15 %.
Medium-Ti basalt flood eruptions have filled much of the center of the Orientale
Basin (>3.70 Ga) and much of the Orientale is again flooded (<3.45 Ga) with
medium-high-Ti basalts. The older medium-Ti basalts are exposed only in west-
central Mare Orientale. The last eruptions in southern-east region of Mare Orientale
are of high-Ti basalts (Kadel et al. 1993 ). Mare Orientale basalts bear high-Ti
concentration and it's calculated through Lucey's 1998 algorithm and M 3 data.
The south central portion's eastern region has TiO 2 in the range of 5-10 wt%,
and the central region basalts have 10-12 wt % of TiO 2 . In few places, the TiO 2
concentration exceeds up to 15 wt%. That most of the places in the Mare Orientale
have >10 wt% of the TiO 2 indicates this region bearing high-Ti basalts. The spectral
profile of the Mare Orientale basalts matching with RELAB's high-Ti mare soils
spectra has confirmed the high-Ti basalts. The TiO 2 concentration map of the Mare
Orientale is shown in Fig. 2.4a .
Hawke et al. ( 1991 ) calculated that Lacus Autumni and Lacus Veris' southern
part bears lower-TiO 2 concentration, while the northern part of the Lacus Veris bears