Premium
Alphonsus Crater: Floor fracture and dark‐mantle deposit distribution from new 3.0‐cm radar images
Author(s) -
Zisk Stanley H.,
Campbell Bruce C.,
Pettengill Gordon H.,
Brockelman Richard
Publication year - 1991
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/91gl02619
Subject(s) - impact crater , geology , graben , volcano , mantle (geology) , seismology , geophysics , tectonics , astrobiology , physics
The lunar crater Alphonsus is characterized by numerous fractures or graben, and by endogenic dark‐halo craters. Existing maps of fractures from analysis of lunar photography may be biased by the east‐west solar illumination. This paper presents new high‐resolution, dual‐polarization 3.0‐cm wavelength radar images of Alphonsus with radar illumination from northerly directions, and uses these data to better map the locations of both the graben and a variety of dark‐mantle deposits. The distribution of fractures, and several graben which cut the crater floor and central ridge, are cited as possible evidence for simultaneous, post‐Imbrium uplift of both structures. Some of the endogenic dark halo deposits are more extensive in depolarized radar images than in photographs; these extensions are attributed in some cases to more distant emplacement of pyroclastic material, and in others to fortuitous connections with smoother, less cratered portions of the Alphonsus floor.