Planetary science: Martian surface paleotemperatures from thermochronology of meteorites

Science

Volumn 309, Issue 5734, 2005, Pages 594-597

  Shuster, David L ^a,c   Weiss, Benjamin P ^b  

^a CALIFORNIA INSTITUTE OF TECHNOLOGY   (United States)

^b MASSACHUSETTS INSTITUTE OF TECHNOLOGY   (United States)

^c BERKELEY GEOCHRONOLOGY CENTER   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

CONSTRAINT THEORY; NATURAL GAS; PETROGRAPHY;

MARTIAN SURFACE TEMPERTURES; METEORITE; THERMOCHRONOLOGY;

MARTIAN SURFACE ANALYSIS;

INERT GAS; WATER;

MARS; METEORITE; PALEOTEMPERATURE;

ARTICLE; ASTRONOMY; COSMOS; ENVIRONMENTAL TEMPERATURE; HEATING; MOLECULAR INTERACTION; PRIORITY JOURNAL; SURFACE PROPERTY; TEMPERATURE; TEMPERATURE DEPENDENCE; TEMPERATURE SENSITIVITY; MICROCLIMATE; TIME;

EXTRATERRESTRIAL ENVIRONMENT; MARS; METEOROIDS; TEMPERATURE; TIME; WATER;

EID: 23044502931     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.1113077     Document Type: Article

References (41)

1. M. Carr, Water on Mars (Oxford Univ. Press, Oxford, 1996).
2. W. K. Hartmann, G. Neukum, Space Sci. Rev. 96, 165 (2001).
3. C. Meyer, Mars Meteorite Compendium-2003 (NASA Johnson Space Center, Houston, TX, 2003), www-curator.jsc.nasa.gov/curator/antmet/mmc/mmc.htm.
4. 39Ar dating of nakhlites and our thermochronology methods are available as supporting material on Science Online.
5. B. P. Weiss, D. L. Shuster, S. T. Stewart, Earth Planet. Sci. Lett. 201, 465 (2002).
6. D. D. Bogard, D. H. Garrison, Meteorit. Planet. Sci. 34, 451 (1999).
7. H. Y. McSween, A. H. Treiman, in Planetary Materials. J. J. Papike, Ed. (Mineralogical Association of America, Washington, DC, 1998), pp. 6-1 to 6-53.
8. O. Eugster, H. Busemann, S. Lorenzetti, D. Terrebilini, Meteorit. Planet. Sci. 37, 1345 (2002).
9. K. Marti, K. J. Mathew, Antarct. Meteorite Res. 17, 117 (2004).
10. R. Ganapathy, E. Anders, Geochim. Cosmochim. Acta 33, 775 (1969).
11. S. V. S. Murty, R. R. Mahajan, J. N. Goswami, N. Sinha, Lunar Planet. Sci. XXXVI, abstract 1280 (2005).
12. K. Terada, T. Monde, Y. Sano, Meteorit. Planet. Sci. 38, 1697 (2003).
13. L. E. Nyquist et al., Space Sci. Rev. 96, 10S (2001).
14. K. Min, P. W. Reiners, Lunar Planet. Sci. XXXVI, abstract 2214 (2005).
15. T. D. Swindle, E. K. Olson, Meteorit. Planet. Sci. 39, 755 (2004).
16. H. Fechtig, S. Kalbitzer, in Potassium-Argon Dating, O. A. Schaeffer, J. Zahringer, Eds. (Springer, Heidelberg, Germany, 1966), pp. 68-106.
17. 39Ar release fractions. Because these four steps were likely derived from a K-poor phase with higher Ar retentivity than the HRD of interest, they were excluded from the total so as not to bias the calculated diffusion coefficients for the lower-temperature extractions.
18. R. Burgess, G. Holland, V. Fernandes, G. Turner, J. Conf. Abs. 5, 266 (2000).
19. 39Ar Method (Oxford Univ. Press, New York, ed. 2, 1999).
20. 2) for the domain that dominates Ar release at those steps. Therefore, this one-domain model places maximum bounds on Ar diffusivity at low-temperature extrapolations. For this regression, the linear subset array was selected for steps between 375° and 675°C.
21. O. M. Lovera, M. Grove, T. M. Harrison, Geochim. Cosmochim. Acta 66, 1237 (2002).
22. 40Ar* accumulation. Because the nakhlites were shock-fractured sometime after their formation (25), we are implicitly assuming that a is smaller than the characteristic distances between cracks and that the diffusion domains are not defined by the bulk geometry of the feldspar fragments.
23. D. L. Shuster, K. A. Farley, Earth Planet. Sci. Lett. 217, 1 (2004).
24. N. Artemieva, B. Ivanov, Icarus 171, 84 (2004).
25. J. Fritz, A. Greshake, D. Stoffler, Lunar Planet. Sci. XXXIV, abstract 1335 (2003).
26. D. W. Collinson, Meteorit. Planet. Sci. 32, 803 (1997).
27. S. A. Gilder, M. LeGoff, J. C. Chervin, J. Peyronneau, Geophys. Res. Lett. 31, L10612 (2004).
28. B. P. Weiss et al., Science 290, 791 (2000).
29. 39Ar age spectra free of trapped Ar for these rocks. (U-Th)/He dating of the shergottite Los Angeles (35) found that the meteorite was strongly heated (to probably at least several hundred degrees C) during ejection, but the peak temperature is not well constrained because the diffusivity of helium in Los Angeles merrillite is not currently known.
30. H. J. Melosh, Nature 363, 498 (1993).
31. J. Laskar et al., Icarus 170, 343 (2004).
32. F. P. Fanale, J. R. Salvail, W. B. Banerdt, R. S. Saunders, Icarus 50, 381 (1982).
33. Cosmic ray exposure data (8) imply that ALH84001 and most of the nakhlites must have been buried at least a few meters deep for nearly all of their histories. The nakhlites are thought to be cumulate rocks that originated in a shallow intrusion or lava flow. Analyses of iron and magnesium zoning in nakhlite olivines (36) suggest that Nakhla and Lafayette formed at depths of 3 to 10 m and >30 m, respectively. These estimates are consistent with but more restrictive than depth estimates inferred from studies of Theo's Flow, which are ultramafic lavas several hundred meters thick thought to be a terrestrial analog for the nakhlite source region (37, 38). ALH84001 probably formed as a cumulate in a deep (several tens of kilometers) intrusion (7). However, given our thermal constraints, two observations suggest that it was later excavated to much shallower depths. First, the thermal gradient on Mars, although not well constrained, is thought to be ∼10°C/km. Second, ALH84001 was strongly shocked at least twice (once before 4 Ga and then again at 4 Ga) (5, 7, 39) and then ejected from Mars without experiencing postshock temperatures greater than 350°C. This suggests that by the 15 Ma ejection event, it resided in the spall zone of the impactor. For a 10-km impactor, this would imply a burial depth of no more than a few kilometers (40).
34. J. C. Bridges et al., Space Sci. Rev. 96, 365 (2001).
35. K. Min, P. W. Reiners, S. Nicolescu, J. P. Greenwood, Geology 32, 677 (2004).
36. T. Mikouchi, E. Koizumi, A. Monkawa, Y. Ueda, M. Miyamoto, Antarct. Meteorite Res. 16, 34 (2003).
37. R. C. F. Lentz, G. J. Taylor, A. H. Treiman, Meteorit. Planet. Sci. 34, 919 (1999).
38. A. H. Treiman, Lunar Planet. Sci. XVIII, 1022 (1987).
39. J. P. Greenwood, H. Y. McSween, Meteorit. Planet. Sci. 36, 43 (2001).
40. H. J. Melosh, Impact Cratering: A Geologic Process (Oxford Univ. Press, Oxford, 1986).
41. We thank T. Swindle and D. Bogard for generously sharing their Ar data with us and for helpful discussions, along with T. Grove, A. Maloof, and J. Eiler. B.P.W, is supported by the NASA Mars Fundamental Research and NSF Geophysics programs.