A small percentage of
Martian impact craters contain alluvial fans; sedimentary
depositional features caused by fluvial transport and identified by
their conical shaped layered deposits and source alcoves. Craters
with alluvial fans generally occur in three specific regional areas
and their pattern of formation is not well understood. For example,
it is unclear why alluvial fans occur in certain craters and not
others with similar size, type, and morphological characteristics.
The large alluvial fans appear to form exclusively within the crater
rims, so the process may be linked to the cratering process itself.
This research focuses on Terra Sabaea, where 7 impact craters
contain alluvial fans, as identified by Moore and Howard (2005). We
analyzed the crater morphology of two groups of craters in this
region; those modified by alluvial fans and those not modified by
alluvial fans. Using the crater characteristics reported in Robbins
and Hynek (2012) database, we compared the two groups. In addition,
we compared the crater rim curvature between the two groups by
selecting representative craters and extracting eight elevation
profiles using gridded MOLA topography. We calculated the curvature
of the crater rims using two different approaches. The first method,
outlined in Moore and Howard (2005) and Kraal et al. (2008),
describes how concave or convex the profile of the crater is. The
second method, used by Mangold et al. (2012), describes the
geometric shape of the crater rim by comparing the rim slope to the
overall crater diameter and shape. We will compare our crater
characteristic results for Terra Sabea to those published for
Margaritifer Terra and Tyrrhena Terra (Mangold, et al. 2012).
Morphology of craters with alluvial fans
in Terra Sabea, Mars
A small percentage of
Martian impact craters contain alluvial fans; sedimentary
depositional features caused by fluvial transport and identified by
their conical shaped layered deposits and source alcoves. Craters
with alluvial fans generally occur in three specific regional areas
and their pattern of formation is not well understood. For example,
it is unclear why alluvial fans occur in certain craters and not
others with similar size, type, and morphological characteristics.
The large alluvial fans appear to form exclusively within the crater
rims, so the process may be linked to the cratering process itself.