REGOLITH LANDFORM
MAPPING OF MERIDIANI
PLANUM AND SURROUNDS
J. D. A. Clarke1 C. F. Pain2 and M. Thomas1,
1Australian
Centre for Astrobiology, Macquarie
University, NSW 2109, Australia,
24
Sticht Place, Florey ACT 2615, Australia
What is Regolith?
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“Regolith” is a general term used to refer to all
weathered earth surface materials extending
from the interface with unweathered bedrock at
depth to the surface.
It includes in situ weathered material derived
directly from the underlying bedrock, and
transported material derived from both bedrock
and other regolith materials
Landforms are used as a proxy for the largely
hidden regolith – this means understanding the
dynamics of past and present landscapes
Regolith on Mars
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Transported regolith is common on Mars, and
can be recognized by its similarities to Earth
regolith
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Fans and alluvial features
colluvial material such as talus deposits
wind-blown sand, volcanic ejecta, and ejecta from
impact craters
Intensely weathered in situ regolith owes its
origin to long periods of geomorphic stability,
and to the presence of water. Regolith resulting
from intense chemical weathering may well be
locally common on Mars
Regolith Landform Mapping
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A regolith landform map shows the
distribution of material at the surface
It uses images derived from a range of
ground, airborne and spaceborne
platforms
Map polygons are based on interpretation
of landforms and their associated regolith
materials
Where possible ground observations are
used for verification
Morphostratigraphic map of Meridiani Terra
(Hynek et al.)
900 km E-W,
with 12
mapping units
based largely
on age and
surface texture
70km west of the
Opportunity landing site
3 km across, allowing
much more detail to be
mapped. Each unit in the
preceding map can be
subdivided on the basis of
regolith materials inferred
from landforms
Opportunity landing site
Surface detail of one
mapping unit, where
a thin veneer of
aeolian sand overlies
eroded sediments
Opportunity landing site
Locally intense
chemical
weathering
producing onion
skin weathering
Last words
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Most geoscience studies of the Martian surface
emphasize geology and mineralogy
A knowledge of regolith will be fundamental to human
explorers on Mars, because they will land on it, set up
bases on it, and travel over it.
In spite of the hundreds of thousands of orbital and
rover images of the Martian surface now available,
interpretation of landforms and regolith on Mars is
dependant on comparison with Earth analogues, and on
models that make assumptions about environmental
conditions and the nature of regolith materials
It is clear that a proper understanding of the Martian
regolith will only be achieved when human explorers get
their hands on it.