Geodynamics Science Highlight
NASA GSFC Geodynamics 921

SCIENCE HIGHLIGHT

Geodynamics Branch, Code 921

September/October 2004

Frey Gives Invited Talks about Buried Basins and Early Mars

Timing of Major Events and Origin of Crustal Dichotomy are Discussed at Two Meetings

The discovery of a very large population of buried impact basins on Mars (most of which are not seen in image data but which can be detected in Mars Orbiter Laser Altimeter elevation data) has led to a significant revision in thinking about the earliest history of the Red Planet. Herb Frey was recently invited to discuss the implications of his discovery of these buried features at two different topical meetings.

Hemispheres Apart: The Origin and Modification of the Martian Crustal Dichotomy held at the Lunar and Planetary Institute on September 30-October 1, 2004
The "Hemispheres Apart" workshop was organized by Patrick McGovern (Lunar & Planetary Institute) and Tom Watters (Center for Earth and Planetary Studies)

At a workshop on Hemispheres Apart: The Origin and Modification of the Martian Crustal Dichotomy held at the Lunar and Planetary Institute on September 30-October 1, 2004, Herb Frey described the evidence that the northern lowland plains are underlain by a very ancient, heavily cratered surface. The great age of this buried surface eliminates several previously suggested mechanisms for creating the lowlands (for example, by plate tectonic processes in middle Mars history). There exist a number of very large ancient impact basins, several of which appear to be "lowland-making" in that much of today's lowlands are within those basins. Frey argued that impact processes are more consistent with both the topography and the inferred relative age of the lowland basement than are most endogenic mechanisms so far proposed, which to date have not yet shown whether the 3-5 km of elevation difference can indeed by created by large scale degree 1 convection.

Second Conference on Early Mars

Buried impact basins are a significant part of the total crater population on Mars. Frey described how the total populations can be used to develop a time-line for major events in the early history of Mars, including the formation of the crustal dichotomy, the likely demise of the global magnetic field, and the time at which the largest impact basins formed. This was the subject of his paper at the Second Conference on Early Mars held at Jackson Hole, Wyoming on October 11-15. The recognition of a large population of buried impact basins even in the relatively well-preserved ancient "Noachian" highlands of Mars strongly suggests that a previously unrecognized "pre-Noachian" era needs to be added to the stratigraphic nomenclature.

hot springs in Yellowstone

The conference, which was very well organized by Steve Clifford (LPI) featured talks both by planetary scientists and specialists in early evolution of life on Earth. A field trip to hot springs in Yellowstone (example, above) provided a glimpse into a possible analog for habitable environments on early Mars.

Contacts: Herb Frey, GSFC, Code 921, Herbert.V.Frey@nasa.gov

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Responsible NASA official: Dr. Herbert Frey

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Last modified on November 9, 2004