Three-dimensional petrography of the Tucson meteorite

1,2Jon M. Friedrich,2,3,4Michael K. Weisberg,1Lucille C. Malecek,2C. E. Nehru
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13751]
1Department of Chemistry, Fordham University, Bronx, New York, 10458 USA
2Department of Earth and Planetary Sciences, American Museum of Natural History, New York, New York, 10024 USA
3Department of Physical Sciences, Kingsborough Community College, Brooklyn, New York, 11235 USA
4Graduate Center of the City University of New York, New York, New York, 10016 USA
Publsihed by arrangement with John Wiley & Sons

We use X-ray microtomography (µCT) and digital data extraction techniques for the three-dimensional (3-D) petrographic investigation of the Tucson meteorite. Our results show that the silicate-free metal regions in Tucson exist as discrete objects surrounded by a continuous silicate-containing metal “matrix.” Volumetric measurements of the silicate-free metal regions in Tucson demonstrate that they are akin to the sizes of metallic nodules found in CBa chondrites. Silicate-free metal regions have bladed or prolate shapes. Nonmetallic minerals in Tucson are predominately equant or prolate in shape. Nonmetallic mineral grains and silicate-free metal regions in Tucson share a common orientation and are part of a petrofabric composed of a lineation. Any foliation in Tucson is weakly developed. We interpret the petrofabric as being the result of a single event on the Tucson parent body, during which Tucson experienced shearing forces. Our 3-D petrographic investigation supports the idea that Tucson is an unusual member of the CR chondrite clan.

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