Imperial College London
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Professor Adrian Muxworthy

Faculty of Engineering, Department of Earth Science & Engineering

Professor of Earth and Planetary Magnetism
 
 
 
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Contact

 

+44 (0)20 7594 6442adrian.muxworthy

 
 
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Location

 

4.48Royal School of MinesSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Muxworthy:2017:10.1111/maps.12918,
author = {Muxworthy, AR and Bland, PA and Davison, TM and Moore, J and Collins, GS and Ciesla, FJ},
doi = {10.1111/maps.12918},
journal = {Meteoritics & Planetary Science},
pages = {2132--2146},
title = {Evidence for an impact-induced magnetic fabric in Allende, and exogenous alternatives to the core dynamo theory for Allende magnetization},
url = {http://dx.doi.org/10.1111/maps.12918},
volume = {52},
year = {2017}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - We conducted a paleomagnetic study of the matrix of  Allende CV3 chondritic meteorite, isolating the matrix’s primary remanent magnetization, measuring  its magnetic fabric and estimating the ancient  magnetic  field  intensity.  A  strong  planar  magnetic  fabric  was  identified;  the  remanent magnetization of the matrix was aligned within this  plane, suggesting a mechanism relating the magnetic fabric and remanence. The intensity of the  matrix’s remanent magnetization was found to be consistent and low (~6 μT). The primary magnetic mineral was found to be pyrrhotite. Given the  thermal  history  of  Allende,  we  conclude  that  the remanent magnetization formed during or after  an  impact  event.  Recent  mesoscale  impact  mode ling,  where  chondrules  and  matrix  are resolved, has shown that low-velocity collisions can generate significant matrix temperatures, as pore-space  compaction  attenuates  shock  energy  and  dramatically  increases  the  amount  of heating.  Non-porous  chondrules  are  unaffected,  and act  as  heat-sinks,  so  matrix  temperature excursions are brief. We extend this work to model Allende, and show that a 1km/s planar impact generates bulk porosity, matrix porosity, and fabric in our target that match the observed values. Bimodal  mixtures  of  a  highly  porous  matrix  and  nominally  zero-porosity  chondrules,  make chondrites uniquely capable of recording transient or unstable fields. Targets that have uniform porosity, e.g., terrestrial impact craters, will not record transient or unstable fields. Rather than a core  dynamo,  it  is  therefore  possible  that  the  origin  of  the  magnetic  field  in  Allende  was  the impact itself, or a nebula field recorded during transient impact heating.
AU  - Muxworthy,AR
AU  - Bland,PA
AU  - Davison,TM
AU  - Moore,J
AU  - Collins,GS
AU  - Ciesla,FJ
DO  - 10.1111/maps.12918
EP  - 2146
PY  - 2017///
SN  - 1086-9379
SP  - 2132
TI  - Evidence for an impact-induced magnetic fabric in Allende, and exogenous alternatives to the core dynamo theory for Allende magnetization
T2  - Meteoritics & Planetary Science
UR  - http://dx.doi.org/10.1111/maps.12918
UR  - http://hdl.handle.net/10044/1/48604
VL  - 52
ER  -
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