In the year 2000 the International Space Science Institute held a workshop on the "Chronology and Evolution of Mars". From this meeting a new view of impact cratering chronology and age-dating of martian meteorites (SNCs) emerged . Continuing analysis of new spacecraft data (MGS, MO, MER, MEX) has provided the information necessary to extend and assess this chronology to a host of geological units and environments. Images from orbit and the surface have revealed the significant role of exhumation in the geological evolution of surfaces. New insights concerning impact fluxes and the influence of secondary cratering processes in impact cratering chronology are emerging. Finally, new analyses of SNC meteorites  and their context have raised fundamental questions about the interpretation of the absolute chronologic basis of the time scale.
For these reasons, the Microsymposium 43 workshop "The Martian Time Scale: Craters, Meteorites, Processes and Stratigraphy" will focus on the discussion of several of these major issues. Each discussion topic will be prefaced by a presentation from an expert in the field, followed by ample time for discussion of the issues. The purpose of the workshop will be to 1) identify the most fundamental unknowns associated with our knowledge of the martian time scale and 2) outline the ways in which we might resolve these questions (new observations, experiments, laboratory analyses, etc.). A product of the Microsymposium will be a written assessment of these points. Among the fundamental questions to be addressed will be:
1) What new developments in Mars cratering chronology have occurred since the ISSI Conference? (Bill Hartmann: PSI)
2) What are the real crystallization ages of the SNC meteorites and what role does alteration play? (Larry Nyquist: NASA JSC)
3) What new insights do we have about Mars cratering chronology from new flux estimates and a better understanding of the impact cratering process? (Boris Ivanov: RAS)
4) What do the new image data tell us about Mars cratering chronology and the major phases of geological activity on Mars? (Gerhard Neukum and Stephanie Werner: Freie Universitaet Berlin)
5) What are the implications of new data on the influence of secondary cratering for Mars cratering chronology? (Alfred McEwen: University of Arizona)
6) What are the implications for Mars Noachian cratering chronology of the detection of additional craters and basins with MOLA data? (Herb Frey: NASA GSFC).
7) What role has exhumation played in the evolution of the surface of Mars and what are the implications for Mars cratering chronology? (Ken Edgett and Mike Malin: MSSS, Invited)
8) How have the new data for Mars changed our perceptions of Mars stratigraphy and geological history? (Ken Tanaka: USGS Flagstaff)
9) What is the importance of in situ analysis and Mars sample return for improving and solidifying Mars cratering chronology? (Glenn MacPherson: Smithsonian Institution)
10) What are the most fundamental questions associated with our knowledge of the martian time scale and how might we resolve these questions (new observations, experiments, laboratory analyses, etc.)? (All)
 Chronology and Evolution of Mars, R. Kallenbach, J. Geiss, and W. Hartmann, eds., Space Science Series of ISSI, vol. 12, Kluwer, Dordrecht, 2001, 498 p. See also Space Science Reviews, vol. 96, Nos. 1-4, 2001.
 A. Bouvier et al., The age of SNC meteorites and the antiquity of the martian surface, EPSL, 240, 221-233, 2005.
The Microsymposium will be held at the Lunar and Planetary Institute in Houston, Texas, beginning at 1 pm on Saturday, March 11, and will conclude Sunday, March 12, by 12 noon. If you are interested in participating in the Microsymposium, please respond to this e-mail by filling in the form below by e-mail reply. The Microsymposium will emphasize an open discussion format anchored by a series of thirty minute invited overviews (see themes and individuals listed above) followed by thirty minutes of discussion and short commentaries. There will also be an opportunity to present posters; in addition to new contributions, if you have a relevant poster that you planned to give at LPSC, you are encouraged to bring it for display and presentation as this will give you the opportunity to show it to a focused audience. Microsymposium 43 complements and sets the stage for aspects of the more broadly focused LPI Workshop "Surface Ages and Histories: Issues in Planetary Chronology" to be held at the LPI May 21-23, 2006.
We ask that responses requesting short commentaries and posters be made as soon as possible but no later than January 17th, 2006 to James_Head@brown.edu. Please indicate "Microsymposium 43" in the subject line. Those wishing to attend the conference can register any time, including up to the time of the conference, but advance notice helps us to plan refreshments and seating. Please forward this announcement to any interested students and colleagues. There is no registration fee.
James Head and Alexander Basilevsky, Co-convenors
In your e-mail response please indicate:
1. Intention to attend Microsymposium 43
2. Intention to make a short 5-minute commentary on one of the themes above:
3. Intention to submit a poster to the Microsymposium:
4. If unable to attend, do you want to be added to the mailing list?
Abstracts from previous Microsymposia:
Micro 42, October 2005