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Mars Eolian Geology at Airphoto Scales: The Large Wind Streaks of Western Arabia TerraMore than 27,000 pictures at aerial photograph scales (1.5-12 m/pixel) have been acquired by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) since September 1997. The pictures are valuable for testing hypotheses about geologic history and processes of Mars. Of particular interest are eolian features connected to surface albedo patterns. This work is focused on low-albedo wind streaks, some over 100 km long, in western Arabia Terra. Each streak is widest where it originates at an impact crater (typically 25-150 km diameter). The streaks taper downwind. Within the associated craters there is a lower-albedo surface that, in nearly all observed cases, includes barchan dunes indicative of transport in the same direction as the wind streaks. Upwind of the dunes there is usually an outcrop of layered material that might have served as a source for dune sand. MOC images show that the west Arabia streaks consist of a smooth-surfaced, multiple-meters-thick, mantle (smooth at 1.5 m/pixel) that appears to be superposed on local surfaces. No dunes are present, indicating that down-streak transport of sediment via saltation and traction have not occurred. Two models might explain the observed properties: (1) the streaks consist of dark silt- and clay-sized grains deflated from the adjacent crater interiors and deposited from suspension or (2) they are remnants (protected in the lee of impact crater rims) of a formerly much larger, regional covering of low albedo, smooth-surfaced mantle. The latter hypothesis is based on observation of low albedo mantled surfaces occurring south of west Arabia in Terra Meridiani. For reasons yet unknown, a large fraction of the martian equatorial regions are covered by low albedo, mesa-forming material that lies unconformably atop eroded layered and cratered terrain. Both hypotheses are being explored via continued selective targeting of new MOC images as well as analyses of the new data.
Document ID
20020000735
Document Type
Conference Paper
Authors
Edgett, Kenneth S.
(Malin Space Science Systems San Diego, CA United States)
Date Acquired
August 20, 2013
Publication Date
July 16, 2001
Subject Category
Lunar And Planetary Science And Exploration
Report/Patent Number
NONP-NASA-CD-2001152919
Meeting Information
Meeting: Summit 2000: Geological Society of America Annual Meeting and Exposition
Location: Reno, NV
Country: United States
Start Date: November 11, 2000
End Date: November 19, 2000
Sponsors: Geological Society of America
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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