NanoPaleoMagnetism

Congratulations to Claire Nichols for being awarded the BGA Best Student Talk prize by the BGA at the recent Magnetic Interactions meeting at Imperial. Her talk entitled “Paleomagnetic and compositional insight into the formation and impact history of the IAB parent body” described her recent synchrotron work on the IAB meteorites – examples of “non-magmatic” iron meteorites that may be derived from a partially differentiated parent body.

Paleomagnetic and compositional insight into the formation and impact history of the IAB parent body

Claire Nichols 1, Geraint Northwood-Smith 1, Julia Herrero-Albillos 2, Florian Kronast 3 and Richard Harrison 1

1 University of Cambridge, 2 Centro Universitario de la Defensa, Universidad de Zaragoza, 3 Helmholtz Centrum Berlin

Traditionally, it has been thought that only two kinds of bodies formed in the solar system: fully melted bodies and completely unmelted bodies. However, it has recently been argued that some planetesimals may have undergone partial differentiation, forming a metallic core while retaining an overlying unmelted or partially melted rocky crust. If correct, this has profound implications for the origin of meteorite groups, the interior structures of asteroids, and the timescale of planetary accretion. The IABs, a group of iron meteorites, may have formed as metallic pools in the mantle of a partially differentiated parent body. Using X-ray photoelectron emission microscopy, we have studied two IABs, Toluca and Odessa, to examine the composition, structure and magnetisation of several FeNi microstructures. Paleomagnetic analysis suggests neither Odessa nor Toluca experienced a magnetic field, with interesting implications for the presence of an active core dynamo on the parent body. The FeNi microstructures present are also exceptional, including a eutectic intergrowth only observed in two meteorite groups. This provides invaluable insight into the thermal history of the parent body and the timing and effect of early impact events.

Well done Claire. £100 worth of biscuits at the next group meeting, please.