Testing the origin of remanent magnetization in the Allende CV3 chondrite using high spatial resolution
Abstract
Multiple studies have confirmed that the Allende CV3 carbonaceous chondrite carries a unidirectional magnetization with Thellier-Thellier paleointensity of ≥20 µT. This observation indicates that Allende was magnetized in the presence of a substantial magnetic field in the early solar system. The nature of this magnetic field has been the subject of debate, with the solar nebula, a core dynamo, impact processes, and the solar wind proposed as possible sources.
Each of these interpretations makes unique, testable predictions for the fine-scale distribution of magnetization. A strong, long-lived magnetic field such as that of the solar nebula or a core dynamo may be recorded as a classical thermoremanent magnetization (TRM), resulting in similar paleointensities in all sub-volumes of the meteorite. On the other hand, a magnetization recording short-lived impact-generated magnetic fields imparted during spatially heterogeneous post-impact heating would persist to different unblocking temperatures in distinct regions. Finally, a solar wind magnetic field record, which would require extremely high magnetization efficiency to explain the high observed paleointensities, implies a non-TRM origin and likely distinct paleointensities associated with different ferromagnetic phases. We will use the quantum diamond microscope (QDM), a magnetic imaging device with ~1 μm maximum spatial resolution, to map the intensity of natural remanent magnetization (NRM) at different demagnetization states. By comparing the spatial distribution of NRM to that of laboratory magnetizations, we will test the above-listed hypotheses for the ancient magnetic field recorded in Allende. Our preliminary mapping of NRM and an isothermal remanent magnetization (IRM) has revealed that the QDM is able to resolve magnetic fields hosted in individual opaque mineral assemblages with ~10 μm diameter, demonstrating the ability of this technique to localize the sources of remanent magnetization.- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMGP43B0795F
- Keywords:
-
- 1507 Core processes;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 1510 Dynamo: theories and simulations;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 1517 Magnetic anomalies: modeling and interpretation;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 1527 Paleomagnetism applied to geologic processes;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 1560 Time variations: secular and longer;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 1595 Planetary magnetism: all frequencies and wavelengths;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 5440 Magnetic fields and magnetism;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS