The paleomagnetic record of pallasite meteorites
Abstract
Pallasites are stony-iron meteorites composed of olivine crystals and Fe-Ni metal. The metal commonly shows a Widmanstatten pattern after etching. Although typically associated with the core-mantle boundary of their parent body, the origin of pallasites is itself contentious. The paleomagnetic record of pallasites is relatively unexplored; here we examine this record and use it to understand more about the nature and fate of pallasite parent bodies. We rely on recent advances in paleomagnetic microanalysis, especially utilizing single silicate crystals hosting magnetic inclusions. Specifically, we focus on the microsampling of olivine crystals from pallasite meterorites and using these samples to obtain paleo-field strength estimates (paleointensity). Preliminary paleointensity data collected using a CO2 laser heating/DC SQUID magnetometer system indicate that fine-grained taenite is preserved in glassy olivine pallasite crystals and that it records a strong thermoremanent magnetization. These data suggest that some pallasites may record an interval of dynamo action in their parent body after the iron-olivine mixing event. We will describe rock magnetic and paleomagnetic studies to further test this hypothesis.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFMGP34A..05T
- Keywords:
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- 1521 GEOMAGNETISM AND PALEOMAGNETISM / Paleointensity;
- 1540 GEOMAGNETISM AND PALEOMAGNETISM / Rock and mineral magnetism;
- 6240 PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS / Meteorites and tektites