Lava flow materials in the Tharsis region of MarsLava-flow materials in the Tharsis region of Mars were studied from moderate-resolution (100-280 m/pixel) Viking Orbiter imagery. Individual eruptive sequences were recognized primarily by stratigraphic relations, density of superimposed impact craters, flow morphology, flow trend, and variations in surface albedo. Nine detailed maps of lava flows based on delineation of flow scarps were compiled for a total area of 7.25 million sq km. Two thirds of this area was covered by mappable flows representing at least 14 distinct eruptive sequences. Assuming a rate of crater production twice that of the moon, the observed range of superimposed crater densities (90 to 3200 craters at least 1 km in diameter per sq km) indicates an age range of 100 m.y. to several billion years for these flows. The youngest lavas are associated with flood lavas filling the depression surrounding the Olympus Mons shield. Flow thicknesses range from less than 5 meters to 20 meters on steeper shield slopes (0.5 to 4.5 deg) and from 20 to 65 meters on relatively flat (less than 0.5 deg slope) terrain.
Document ID
19790055277
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Schaber, G. G. (Geological Survey Flagstaff, AZ, United States)
Horstman, K. C. (Geological Survey Flagstaff, AZ, United States)
Dial, A. L., Jr. (U.S. Geological Survey, Branch of Astrogeologic Studies, Flagstaff Ariz., United States)