Quantitative Characterization of Lunar Mare Orientale Basalts Detected by Moon Mineralogical Mapper on Chandrayaan-1 - Planetary Exploration and Science: Recent Results and Advances - page 37

Fig. 2.8 High-Ti ( a )andlow-Ti( b ) basalts distribution map of Lacus Autumni

the range of 21 % in most of the Lacus Autumni, but in some specific locations, the
content of the Low-Ti basalts exceeds up to 70-80 %, which is shown in Fig. 2.8b
in the colors of cyan and magenta. There is no much amount of medium-Ti basalt
distribution in the Lacus Autumni region.
The clinopyroxene (CPX) in the central part of the Lacus Autumni is around
32 %. The outside of the Lacus Autumni, CPX concentration varies in the range
from 32 to 42 %. The southern-east portion of the Lacus Autumni has slightly lower
CPX with the amount of 26 %. There is no much amount of OPX measured in
the Lacus Autumni region. The plagioclase content of the Lacus Autumni is 27 %,
21 % in central part and 30 % in external side of the Lacus Autumni. The olivine
concentration of the Lacus Autumni is nearly 4 %. The western portion of the Lacus
Autumni has lower olivine content compared to the central portion. The impact
craters on the Lacus Autumni have slightly higher olivine content that is nearly up
to 5 %. It could be due to excavation of deeper material due to impact.

2.4.4 Age of Mare Orientale, Lacus Veris, and Lacus Autumni

Compared with lunar highland, mare basalts occupy lesser area, but they contain
much information about the thermal history of the moon and the nature of the lunar
interior (Head 1976 ). The age of mare basalts studied is between 3.15 and 3.96 Gy.
But recent photogeologic (crater-counting) studies indicate that there are 2.5-Gy-
old younger basalts on the moon, which yet to be sampled. The returned samples
were classified into two broad categories based on the TiO 2 concentration: high-
titanium group (ages 3.55-3.85 Gy; TiO 2, 9-14 wt%) and the low-titanium group
(ages 3.15-3.45 Gy; TiO 2, 1-5 wt%). Basalts returned by Apollo 11 and 17 are
dominated by high-titanium group including olivine and ilmenite, whereas Apollo
12 and 15 and Luna 16 returned samples dominated by low-titanium group which is
almost olivine (Head 1976 ).