On the Highland Crust Diversity and Mare-Highland Transitions in the Mare Humorum Region of the Moon
P.D. Martin (PGD/HIGP/SOEST, Univ. of Hawaii), P.C. Pinet, S.D. Chevrel, Y.H. Daydou (UMR5562/CNRS/OMP, Toulouse, FRANCE)
We present a high spatial resolution (340m) analysis of the spectral and
compositional properties of the lunar surface, focused on the Humorum
basin region. The processing and calibration of more than 2000 raw
Clementine frames has led to the production of an extended (600 kms x
450 kms) multispectral image-cube in the 0.40-1.0 micron wavelength
range. The spatial information derived from a linear mixing modeling as
well as from the information of maturity and titanium (mare units) and
iron abundance, is discussed in relation with the previous interpretations
of remotely-sensed data of the region. The following inferences are made
in an attempt to characterize the nature and origin of the spectrally
identified materials. The spectral properties of the most extended western
highland unit exhibit a concentric distribution which is found associated
with the ring structure of the basin. In particular, on the mare-bounding
ring, we have established the presence of an extended pure anorthosite
unit (Fe content <3%). Another highland area, low in topography and
located northwest of Mersenius toward Herigonius and Letronne regions,
has spectral characteristics indicating undefined deposit materials, with
local mare-like contributions. Within the southwestern highlands (25 to
100 kms from the basin's boundary), the spectral features of the darkest
terrains indicate mare optical properties, possibly related to the
presence of cryptomare deposits. The study of mare-highland relations
reveals the great complexity of the region, with variable mixing gradients
suggesting different processes of physical mixing of materials throughout
the geologic boundaries of the basin.