AGU journal highlights -- Sept. 6, 2007(he convergence zones southward shift. Ad...)

Title:
Abrupt climate change in southeast tropical Africa influenced by Indian monsoon variability and ITCZ migration

Authors:
Jessica E. Tierney and James M. Russell: Department of Geological Sciences, Brown University, Providence, Rhode Island, U.S.A.

Source:
Geophysical Research Letters (GRL) paper 10.1029/2007GL029508, 2007, http://dx.doi.org/10.1029/2007GL029508

Antarctica represents the best site to collect small meteoritic particles because windblown terrestrial dust is scarce and extreme environmental conditions prevent chemical weathering. Although many investigations have searched for micrometeorites deposited within modern times, few have looked for them within ancient ice. As part of a new micrometorite collection project launched at the permanent French-Italian station of Concordia, on the East Antarctic Plateau, Narcisi et al. study the Dome C ice core, a core collected by the European Project for Ice Coring in Antarctica. They find two distinct dust layers which, through comparisons with extraterrestrial debris found in deep-sea sediments and polar caps, they determined to be of meteoritic origin. Closer inspection revealed that these layers represented individual meteoritic events, with the first occurring about 481,000 years ago and the second occurring 434,000 years ago, as indicated by layers in the ice core. The authors note that, similar to ashfall from a known volcanic explosion, such meteoritic events have the potential to serve as time markers in other less detailed stratigraphic records.

Title:
First discovery of meteoritic events in deep Antarctic (EPICA-Dome C
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