Carbonaceous micrometeorites from Antarctica (Invited Review)

• Published in: Meteoritics & Planetary Science
• Main Authors: Engrand, Cécile, Maurette, Michel
• Other Authors: University of California Los Angeles (UCLA), University of California (UC), Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 1998
• Subjects: [SDU]Sciences of the Universe [physics]; Antarctic; Greenland; Antarc*; Antarctica
• Online Access: https://hal.in2p3.fr/in2p3-02114750; https://hal.in2p3.fr/in2p3-02114750/document; https://hal.in2p3.fr/in2p3-02114750/file/Engrand_1998_AMMs.pdf; https://doi.org/10.1111/j.1945-5100.1998.tb01665.x

International audience Over 100 000 large interplanetary dust particles in the 50-500 pm size range have been recovered in clean conditions from-600 tons of Antarctic melt ice water as both unmelted and partially melteddehydrated micrometeorites and cosmic spherules. Flux measurements in both the Greenland and Antarctica ice sheets indicate that the micrometeorites deliver to the Earth's surface-2OOOx more extraterrestrial material than brought by meteorites. Mineralogical and chemical studies of Antarctic micrometeorites indicate that they are only related to the relatively rare CM and CR carbonaceous chondrite groups, being mostly chondritic carbonaceous objects composed of highly unequilibrated assemblages of anhydrous and hydrous minerals. However, there are also marked differences between these two families of solar system objects, including higher C/O ratios and a very marked depletion of chondrules in micrometeorite matter; hence, they are "chondrites-without-chondrules." Thus, the parent meteoroids of micrometeorites represent a dominant and new population of solar system objects, probably formed in the outer solar system and delivered to the inner solar system by the most appropriate vehicles, comets. One of the major purposes of this paper is to discuss applications of micrometeorite studies that have been previously presented to exobiologists but deal with the synthesis of prebiotic molecules on the early Earth, and more recently, with the early history of the solar system.