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| Titel |
Paleomagnetism of the Rochechouart Meteorite Impact Crater: Field Reversal or Self Reversal? |
| VerfasserIn |
M. Eitel, S. Gilder, J. Pohl |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250061069
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| Zusammenfassung |
| Paleomagnetic investigations on the Rochechouart (France) impact structure reveal three kinds of stable magnetization directions: solely normal, solely reversed and samples with multiple, often antipodal, magnetization components. Possible explanations for this observation are: (1) the rocks record a geomagnetic field reversal during the time it took the impact melts and suevites to cool through the Curie blocking temperature, and (2) a self-reversal mechanism is to blame. In order to distinguish between the two possibilities, the rocks have been investigated by detailed stepwise thermal demagnetization, rock magnetic and Thellier-Thellier paleointensity experiments. Determinations of the Curie temperatures reveal a well-defined grouping correlating with the sampling locality. The reproducibility of a self-reversal has been tested by imparting a laboratory TRM to the samples followed by stepwise thermal demagnetization. No evidence for a self-reversal was found. In order to examine the reproducibility of a geomagnetic field reversal a further experiment was performed by reversing the direction of the artificial magnetic field during cooling of the rocks. Stepwise demagnetization revealed only a single polarity. We will also present observations from optical, thin section and scanning electron microscopy that provide information about the magnetic mineralogy of the rocks. |
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