http://skyandtelescope.com/news/current/article_585_1.asp
Mystery Meteorite with a Molten Past Sky & Telescope News Brief April 25, 2002 Planetary scientists suspect that many primordial asteroids must have grown large enough to melt completely, yielding iron-rich cores and silicate crusts before being shattered to pieces. After all, the iron meteorites reaching Earth comprise dozens of unique compositional types. Yet, among the thousands of known meteorites, only a relative handful consist of basalt, the igneous rock type that would be most common in those asteroidal crusts - and until recently all of them seemed to have come from a single source, 4 Vesta. In the April 12th issue of Science, Akira Yamaguchi (National Institute of Polar Research, Tokyo) and nine colleagues argue that a 40-gram stone called Northwest Africa 011 is a basaltic meteorite entirely unlike those from Vesta. Its parent body is unknown; one candidate is 1459 Magnya, an outer-belt object that was found to have a basalt spectrum two years ago. Still, though lacking a pedigree, NWA 011 is a significant find. As asteroid expert Richard P. Binzel (MIT) explains, "Yamaguchi's results (and those for 1459 Magnya) are the 'eureka' that complement what the iron meteorites have been telling us: there must have been other Vestas out there." Online access to Science is restricted, but Yamaguchi's abstract can be found at: http://www.sciencemag.org/cgi/content/short/296/5566/334. -------------------------------------------------------------------------- http://www.sciencemag.org/cgi/content/short/296/5566/334 A New Source of Basaltic Meteorites Inferred from Northwest Africa 011 Akira Yamaguchi,[12*] Robert N. Clayton,[3] Toshiko K. Mayeda,[3] Mitsuru Ebihara,[4] Yasuji Oura,[4] Yayoi N. Miura,[5] Hiroshi Haramura,[1] Keiji Misawa,[12] Hideyasu Kojima,[12] Keisuke Nagao[6] Eucrites are a class of basaltic meteorites that share common mineralogical, isotopic, and chemical properties and are thought to have been derived from the same parent body, possibly asteroid 4 Vesta. The texture, mineralogy, and noble gas data of the recently recovered meteorite, Northwest Africa (NWA) 011, are similar to those of basaltic eucrites. However, the oxygen isotopic composition of NWA011 is different from that of other eucrites, indicating that NWA011 may be derived from a different parent body. The presence of basaltic meteorites with variable oxygen isotopic composition suggests the occurrence of multiple basaltic meteorite parent bodies, perhaps similar to 4 Vesta, in the early solar system. 1 Antarctic Meteorite Research Center, National Institute of Polar Research, Tokyo 173-8515, Japan. 2 The Graduate University for Advanced Studies, Tokyo 173-8515, Japan. 3 Enrico Fermi Institute, University of Chicago, Chicago, IL 60637, USA. 4 Department of Chemistry, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan. 5 Earthquake Research Institute, University of Tokyo, Tokyo 113-0032, Japan. 6 Laboratory for Earthquake Chemistry, University of Tokyo, Tokyo 113-0033, Japan. * To whom correspondence should be addressed. E-mail: [EMAIL PROTECTED] ______________________________________________ Meteorite-list mailing list [EMAIL PROTECTED] http://www.pairlist.net/mailman/listinfo/meteorite-list
