Micrometeorites from the Transantarctic Mountains

doi:10.1073/pnas.0806049105

Micrometeorites from the Transantarctic Mountains

^aCentre Européen de Recherche et d'Enseignement des Géosciences de l'Environnement, Aix-Marseille Université-Centre National de la Recherche, PB80 13545, Aix en Provence, Cedex 4, France;
^bMuseo Nazionale dell'Antartide, Università di Siena, Via Laterina 8, 53100 Siena, Italy;
^cDipartimento di Scienze della Terra, Università di Pisa, Via S. Maria 53, 56126 Pisa, Italy; and
^dDepartment of Geological Sciences, Case Western Reserve University, 0900 Euclid Avenue, Cleveland, OH 44106

Edited by Norman H. Sleep, Stanford University, Stanford, CA, and approved October 7, 2008 (received for review June 25, 2008)

Abstract

We report the discovery of large accumulations of micrometeorites on the Myr-old, glacially eroded granitic summits of several isolated nunataks in the Victoria Land Transantarctic Mountains. The number (>3,500) of large (>400 μm and up to 2 mm in size) melted and unmelted particles is orders of magnitudes greater than other Antarctic collections. Flux estimates, bedrock exposure ages and the presence of ≈0.8-Myr-old microtektites suggest that extraterrestrial dust collection occurred over the last 1 Myr, taking up to 500 kyr to accumulate based on 2 investigated find sites. The size distribution and frequency by type of cosmic spherules in the >200-μm size fraction collected at Frontier Mountain (investigated in detail in this report) are similar to those of the most representative known micrometeorite populations (e.g., South Pole Water Well). This and the identification of unusual types in terms of composition (i.e., chondritic micrometeorites and spherulitic aggregates similar to the ≈480-kyr-old ones recently found in Antarctic ice cores) and size suggest that the Transantarctic Mountain micrometeorites constitute a unique and essentially unbiased collection that greatly extends the micrometeorite inventory and provides material for studies on micrometeorite fluxes over the recent (≈1 Myr) geological past.

Footnotes

¹To whom correspondence should be addressed. E-mail: folco{at}unisi.it
Author contributions: P.R. and L.F. designed research; P.R., L.F., C.S., M.v.G., J.G., N.P., and R.B. performed research; R.P.H. contributed new reagents/analytic tools; P.R., L.F., C.S., M.v.G., J.G., N.P., and R.B. analyzed data; and P.R. and L.F. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
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