Venus' Craters, Coronae, and Chasmata: What's Going On?

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Venus' Craters, Coronae, and Chasmata What's
Going On?

• Paul Stoddard
• Dept. of Geology and Environmental Geosciences
• Northern Illinois University

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Early View of Venus
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Occultation Study
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Venus, as seen by Veneras 9 and 10
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Venus as seen by Venera 13 (1-Mar-1982)
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Pioneer Venus Topography
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Inner Solar System Hypsographic Comparisons
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Magellan Deployment
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Magellan Mapping Schematic
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Venus Chasmata, Coronae, Craters, and Geoid
(Eckert IV projection)
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The Beta-Atla-Themis (BAT) Region of
Venus(Mercator Projection)
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Beta-Atla-Themis (BAT) Region
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Craters

• About 1000 globally
• Apparent random distribution
• Most pristine, some modified
• Tectonization
• Embayed
• West-opening Haloes (very young craters)

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Craters on Venus
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Chasmata

• Probable analog to Earth rifts
• Total length of Venus chasmata system similar
  (when adjusted for planetary radius) to that of
  Earths rift system (within 95)

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Venus Chasmata Example
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Coronae

• Large volcanic features, marked by central
  topographic high or low, surrounded by annulus
• About 670 identified
• Not randomly distributed concentrations near
  chasmata and in the B-A-T region
• Possible evolution scheme determined

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Venus Volcanoes
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Sif Mons
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Shield Field
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Pancake Domes
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Coronae
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Corona Evolution
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Sample Comparison of Coronae, by Type
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Craters vs. Coronae

• Recently, several researchers (Hamilton,
  Vita-Finzi, e.g.) have suggested that coronae are
  actually craters.
• Comparison of topography may help assess this
  hypothesis.

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Ninhursag Corona or Crater?
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Mead Crater Radar and Topography
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Cross-Correlation Example
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Klenova -Crater or Corona?
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Interplanetary Cross-Correlations
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Conclusions

• While Venus closely resembles Earth on a global
  scale, there are very significant differences
  between the two
• Atmospheric composition, density, and temperature
• Tectonic style
• Volcanic style
• Crater distribution

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Conclusions

• Venus may have been totally resurfaced in a very
  short time frame (100 Ma?) between 300 Ma and 1
  Ga.
• This history will have to be rewritten if
  features classified as coronae are actually
  craters
• Preliminary analysis indicates that
  classification must be done carefully, on a
  feature-by-feature basis

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Conclusions

• Venus Remains Enigmatic
• Venus Remains Mysterious
• Venus Remains a Riddle