Two new eucrite breccias from Northwest Africa |
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| Authors: | Sheryl A SINGERLING Aubrey L MODI Blake MCFERRIN Emily A WORSHAM Harry Y MCSWEEN JR Douglas RUMBLE III Ryoji TANAKA Lawrence A TAYLOR |
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| Institution: | 1. Planetary Geosciences Institute, Department of Earth & Planetary Sciences, University of Tennessee, Knoxville, Tennessee 37996‐1410, USA;2. Department of Geology, University of Maryland, College Park, MD 20742, USA;3. Geophysical Laboratory, Carnegie Institution for Science, Washington, DC 20015, USA;4. The Pheasant Memorial Laboratory, Institute for Study of the Earth’s Interior, Okayama University, Misasa, Tottori, 682‐0193, JAPAN |
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| Abstract: | Abstract– This work describes two newly discovered eucrite breccias: three presumably paired meteorites, all named Northwest Africa (NWA) 6105, and NWA 6106. For each meteorite, major‐ and minor‐element compositions of minerals were determined using the electron microprobe. Pyroxene Fe‐Mn co‐variations and bulk‐rock oxygen isotope compositions confirm their classification as eucrites. Variations in mineral compositions and textures are attributed to differences in clast types present (i.e., basaltic or cumulate eucrite). The pyroxene compositions support the hypothesis that samples NWA 6105,1; 6105,2; and 6105,3 are paired polymict eucritic breccias, whereas sample NWA 6106 is a monomict basaltic eucritic breccia. Two‐pyroxene geothermometry yields temperatures too low for igneous crystallization. The variation in temperatures among samples suggests that metamorphism occurred prior to brecciation. |
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