2000 GSA Annual Meeting -- Reno, Nevada

Abstract 50511

MARS EOLIAN GEOLOGY AT AIRPHOTO SCALES: THE LARGE WIND STREAKS OF WESTERN ARABIA TERRA.

Presented by Edgett, K. S.

Key words: Mars, eolian, sediment, martian, dunes

In Session 136     Planetary Geology: Insights Into Mars Wednesday, November 15, 2000 AM in Room: Ballroom D at 08:15 AM for 15 min .

Abstract: More 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.

Summit 2000 Page

GSA Home Page


(c) Copyright 2000 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely (including on their Web site), for noncommercial purposes providing the posting is identical to the submitted abstract and includes this reference: "The full paper was presented at the 2000 Geological Society of America Annual Meeting held in Reno, Nevada, November 13-16, 2000." Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce an unlimited number of paper copies for noncommercial purposes advancing science and education, specifically including classroom use. Copies reproduced within these permissions must include the author information and this copyright statement. All other forms of capture, reproduction, and/or transmittal are prohibited without written permission from GSA Copyright Permissions. All abstracts were published in GSA Abstracts with Programs, volume 32, number 7 (Annual Meeting), available from the Geological Society of America, P.O. Box 9140, Boulder, Colorado 80301-9140 USA; phone (303) 447-2020, e-mail member@geosociety.org.