Between 2 and 3 Myr before the present, the Earth was subjected to the debris of a supernova explosion. First evidence for this was the presence of a concentration spike of live atoms of 60Fe in a Pacific ocean ferromanganese crust. This signal was found using accelerator mass spectrometry (AMS). The known cosmic site for the production of 60Fe is core collapse supernova. Subsequent searches in marine sediments for this signal failed.
We now report on a new detection of live 60Fe found in a new terrestrial reservoir; namely, biogenically produced magnetite crystals, that are now fossilized -- so-called magnetofossils. The occurance in the geological record is ~2.5 Myr before the present. This contribution will explain the motivation to search in magnetofossils for this signature, and show our preliminary results of the 60Fe signal.
| Subject : | : | oral |
| Topics | : | topic1 |
| PDF version | : |  PDF version |
