Lead from historical gasoline use continues to affect air quality in urban London almost 20 years after its phase-out.
Image credit: Eléonore Resongles and Volker Dietze.
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Edited by Mark H. Thiemens, University of California at San Diego, La Jolla, CA, and approved February 20, 2009 (received for review January 13, 2009)
Abstract
Micrometeorites with diameter ≈100–200 μm dominate the flux of extraterrestrial matter on Earth. The vast majority of micrometeorites are chemically, mineralogically, and isotopically related to carbonaceous chondrites, which amount to only 2.5% of meteorite falls. Here, we report the discovery of the first basaltic micrometeorite (MM40). This micrometeorite is unlike any other basalt known in the solar system as revealed by isotopic data, mineral chemistry, and trace element abundances. The discovery of a new basaltic asteroidal surface expands the solar system inventory of planetary crusts and underlines the importance of micrometeorites for sampling the asteroids' surfaces in a way complementary to meteorites, mainly because they do not suffer dynamical biases as meteorites do. The parent asteroid of MM40 has undergone extensive metamorphism, which ended no earlier than 7.9 Myr after solar system formation. Numerical simulations of dust transport dynamics suggest that MM40 might originate from one of the recently discovered basaltic asteroids that are not members of the Vesta family. The ability to retrieve such a wealth of information from this tiny (a few micrograms) sample is auspicious some years before the launch of a Mars sample return mission.
Footnotes
- 1To whom correspondence should be addressed. E-mail: gounelle{at}mnhn.fr
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Author contributions: M.G. designed research; M.G., M.C., A.M., J.-A.B., C.E., M.E.Z., and K.D.M. performed research; M.G., M.C., A.M., J.-A.B., C.E., M.E.Z., and K.D.M. analyzed data; and M.G. wrote the paper.
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The authors declare no conflict of interest.
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This article is a PNAS Direct Submission.
A unique basaltic micrometeorite expands the inventory of solar system planetary crusts
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