Mineral compositions in Antarctic and Greenland micrometeorites

• Published in: Meteoritics
• Main Authors: Michel‐Levy, Mireille Christophe, Bourot‐Denise, Michèle
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1992
• Subjects: General Earth and Planetary Sciences; General Environmental Science; Antarctic; Greenland; Antarc*
• Online Access: http://dx.doi.org/10.1111/j.1945-5100.1992.tb01057.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1945-5100.1992.tb01057.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1945-5100.1992.tb01057.x

Abstract— The mineral compositions of 250 micrometeorites have been studied and olivines and low‐calcium pyroxenes with crystals larger than 5 μm have been analyzed. While magnesium‐rich grains dominate, the Fa content of olivine may reach 50% and the Fs content of pyroxene may reach 26%. The Ca and Mn of the olivine show no consistent trends with increasing Fe, but Cr shows a negative correlation. For low‐Ca pyroxene, Al and Cr contents are generally higher than in pyroxenes of equilibrated chondrites but similar to those of highly unequilibrated chondrites. Calcium‐bearing pyroxene, feldspar and chromite are rare in the micrometeorites which were selected because of their high Mg, Si, Fe and their low Ca and Al content. All these minerals are found as coarse‐grained particles often with adhering iron‐rich scoria or as clasts in fine‐grained or scoriaceous micrometeorites. Apart from a few particles which could be the debris of ordinary chondrites, most micrometeorites probably come from a common source similar, but not identical to carbonaceous chondrites, as shown by their lower Ni and S content and their different oxygen isotopic composition assuming two measurements performed on olivine grains prove to be typical.