Raised
Curvilinear Features on Mars: Inverted Paleochannels in the Martian
Stratigraphy
Williams, Rebecca M. E.1 (1)
Planetary Science Institute,
Bifurcating ridge networks, termed
‘raised curvilinear features' (RCFs), covering areas ranging from tens to
hundreds of square kilometers have been identified at over one hundred sites on
Mars in high resolution (<100 meters per pixel) images. Based on their
similarity to terrestrial fluvial landforms, RCFs have been universally
interpreted as resulting from aqueous flow. Many RCFs have diagnostic
morphological attributes consistent with formation by continually flowing water
now expressed in inverted relief. Channel floors on Mars likely became
indurated primarily by cementation, with clast armoring potentially operating
in a secondary role. Today, the valley systems are the products of the combined
forces of burial, exhumation and erosion that resulted in the former channel
floor now preserved as a topographic high. Two attributes of some RCFs, particularly
those proximal to Valles Marineris, are consistent with precipitation-fed
runoff to generate the volumes of liquid necessary for valley network
formation: a) preservation of low-order tributaries (rarely observed on Mars),
and b) drainage density values (0.9-2.3 km-1) among the highest
reported for Martian fluvial landforms and similar to terrestrial stream
systems of comparable scale. The suite of RCF morphologies preserved on Mars
document a range of paleofluvial environments attesting to the complex fluvial
history on the planet. In locations with multiple RCFs, they occur at different
levels within the layered stratigraphy. The stratigraphic context of RCFs
indicates that precipitation-fed runoff occurred in locations beyond the period
of heavy impact cratering that ended 3.8 billion years ago.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California