PSJC #66 Apr 23 2010

Robert Macke

Characterization of meteorite structure and porosity.

Bulk and grain density measurements alone only yield an overall percentage of pore space, but there is much that they fail to tell us. For example, how is the pore space distributed? Is it located in small intergranular spaces in the chondrite matrix, in cracks, or even in extended voids? Each of these possibilities has important implications for parent body origin, history, and strength. Understanding the character of pore space is important for interpreting porosity measurements. Investigators are approaching this question in different ways. SEM studies of thin sections allow researchers to look directly at pore spaces of samples with large cross-sectional areas. X-ray microtomography enables exploration of the interiors of solid (albeit small) volumes, establishing pore size distributions and, in recent work, distinguishing cracks from other pore types in 3 dimensions, X-ray micro-CT is also being developed for characterization of shape and bulk volume for larger meteorite samples. This talk will be based on the work of Melissa Strait (Alma College), Jon Friedrich (Fordham University), Phil McCausland (Univ. of Western Ontario), and others.

Some relevant references:

• Strait M. and Consolmagno G.J., "Visualizing porosity in meteorites," 41st Lunar and Planetary Science Conference, 2010.
• McCausland P.J.A., Brown P.G. and Holdsworth D.W., "Rapid, reliable acquisition of meteorite volumes and internal features by laboratory x-ray micro-CT scanning," 41st Lunar and Planetary Science Conference, 2010.
• Sasso M.R., Macke R.J., Britt, D.T., Rivers, M.L., Ebel D.S., and Friedrich J. M., "Physical properties of incompletely compacted equilibrated ordinary chondrites: Implications for asteroidal structure and impact processing," 40th Lunar and Planetary Science Conference, 2009.