Remote Investigation of compositionally distinct lithologies at and
around the central peaks of some recent craters and their implications
for crater modification process
Abstract
Central peaks of lunar complex craters of Copernican period provide best
examples to study morphologies of impact melts and exposed subsurface as
they are better preserved and less affected by the space weathering.
Crater Tycho, present towards SW, nearside of the Moon is one such
example of young and fresh complex crater. Present study is
high-resolution mineralogical investigation coupled with morphological
study of central peaks and floor of crater Tycho and other contemporary
craters to understand the nature of occurrence and distribution of
compositionally distinct lithologies identified near their central peaks
that differ in colour and specific appearance. A detailed
high-resolution analysis suggests that the clastic exposures associated
with the melts have a mafic composition that have been observed at
similar other contemporary craters. They represent the fragmental
polymict breccia clasts and their stratigraphic relation with the melts
alongwith with their mineralogy suggests them to be representative of
subsurface anorthositic gabbro/noritic body. Their occurrence and
association with structural features, such as breccias dikes and cooling
cracks suggest their formation at different stages of cratering and
associated crustal modification. The formation mechanism of the polymict
breccia clasts causing lithological variability has been discussed. We
also report here the occurrence of rejuvenated dykes peculiar to Tycho
setting that are distinct from the fractures in the immediate viscinity.
Their unique nature suggests different emplacement mechanism associated
with dynamic cratering process till not reported at any young complex
crater on the Moon.