Geoscience Reference
In-Depth Information
M
3
images with high spatial and spectral resolution can be used to count the
craters for given size on the Mare Orientale, Lacus Veris, and Lacus Autumni and to
produce the reliable model. In mare Orientale, craters >5 km were counted on the
Hevelius formation and craters >0.75 km were counted on the Maunder formation.
This crater count method calculated that ages are
3.68 Ga for the ejecta and
3.64 Ga for the melt sheet. Orientale was emplaced shortly after the Maunder
formation in
3.58 Ga. This delay of
60-100 Ma between basin formation and
volcanism in three study areas argues against Orientale impact-pressure-release
melting ages (Whitten et al.
2011
).
In the Lacus Veris, the crater count chronology deduced the age of five largest
ponds in the range of
3.20 to
3.69 Ga (Whitten et al.
2011
), which is consistent
with the previous studies conducted by Greeley et al. (
1993
) and Kadel (
1993
).
In the Lacus Autumni, crater counts give an age range between
3.47 and
1.66 Ga (Whitten et al.
2011
). The young model age of
1.66 Ga falls well
within the calculated time range of mare volcanism occurring on the lunar nearside
(Hiesinger et al.
2000
). This discrepancy in the model ages could be the result of
sizeable differences in the definition of the count area or count statistics used. The
detailed discussion can be found in Whitten et al. (
2011
) and relevant references.
2.4.5
Validation
The results revealed from the RELAB spectra and chemical data have been used to
validate the result of this present research. Apart from the RELAB data, the results
have been compared with the previous Clementine UVVIS data global mineral
mapping study conducted by Bokun et al
2010
. The RELAB low-, medium-, and
high-Ti basaltic spectra were compared with Mare Orientale, Lacus Veris, and
Autumni spectra established from M
3
data, which is shown in Fig.
2.9
.Inthis,
0.30
Low Ti Average
Medium Ti Average
High Ti Average
Mare Orientale
Lacus Veris
Lacus Autumni
0.25
0.20
0.15
0.10
0.05
500
1000
1500
2000
2500
Wavelength nm
Fig. 2.9
Low-, medium- and high-Ti basalts spectra with Mare Orientale, Lacus Veris and Lacus
Autumni spectra
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