Constraints on early events in Martian history as derived from the cratering record

Conference · Thu Aug 30 04:00:00 EDT 1990 · Journal of Geophysical Research; (United States)

OSTI ID:5313956

Barlow, N G ^[1]

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1. Lunar and Planetary Institute, Houston, TX (USA)

The shapes and densities of crater size-frequency distribution curves are used to constrain two major events early in Martian history: termination of high obliteration rates and viability of the multiple impact origin of the crustal dichotomy. Distribution curves of fresh craters superposed on uplands, intercrater plains, and ridged plains display shapes and densities indicative of formation prior to the end of heavy bombardment. This observation correlates with other geologic evidence, suggesting a major change in the erosional regime following the last major basin size impact (i.e., Argrye). In addition, the multisloped nature of the curves supports the idea that the downturn in the crater size-frequency distribution curves reflects the size-frequency distribution of the impactors rather than being the result of erosion. The crustal dichotomy formed prior to the heavy bombardment intermediate epoch based on distribution curves of knobby terrain; if the dichotomy resulted from a single gigantic impact, this observation places constraints on when this event happened. An alternate theory for dichotomy formation, the multiple-impact basin idea, is questioned: since distribution curves of large basins as well as heavy bombardment era units are not represented by a {minus}3 differential power law function, this study finds fewer basins missing on Mars compare to the Moon and Mercury than previously reported. The area covered by these missing basins is less than that covered the northern plains.

• OSTI ID: 5313956
• Report Number(s): CONF-9001119--
• Conference Information: Journal Name: Journal of Geophysical Research; (United States) Journal Volume: 95:B9
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics & Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CAVITIES
COLLISIONS
COMPARATIVE EVALUATIONS
CRATERS
DENSITY
DISTRIBUTION
EROSION
EVALUATION
GEOLOGY
MARINER SPACE PROBES
MARS PLANET
MERCURY PLANET
MOON
ORIGIN
PHYSICAL PROPERTIES
PLANETARY EVOLUTION
PLANETS
SATELLITES
SOLAR SYSTEM EVOLUTION
SPACE VEHICLES
VEHICLES
VIKING SPACE PROBES