Nichols, C.I.O.; Bryson, J.F.J.; Cottrell, R.D.; Fu, R.R.; Harrison, R.J.; Herrero-Albillos, J.; Kronast, F.; Tarduno, J.A.; Weiss, B.P.: A Time-Resolved Paleomagnetic Record of Main Group Pallasites: Evidence for a Large-Cored, Thin-Mantled Parent Body. Journal of Geophysical Research : Planets 126 (2021), p. e2021JE006900/1-21
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Several paleomagnetic studies have been conducted on ve main group pallasites: Bren- ham, Marjalahti, Springwater, Imilac and Esquel. These pallasites have distinct cooling histories, meaning that their paleomagnetic records may have been acquired at dierent times during the thermal evolution of their parent body. Here we compile new and existing data to present the most complete time-resolved paleomagnetic record for a planetesimal, which includes a period of quiescence prior to core solidication as well as dynamo ac- tivity generated by compositional convection during core solidication. We present new paleomagnetic data for the Springwater pallasite, which constrains the timing of core solid- ication. Our results suggest that in order to generate the observed strong paleointensities (∼ 65 95 μT), the pallasites must have been relatively close to the dynamo source. Our thermal and dynamo models predict that the main group pallasites originate from a plan- etesimal with a large core (> 200 km) and a thin mantle (< 70 km). The density of our model large-cored planetesimals is similar to the predicted density of the asteroid (16) Psyche. We therefore suggest that it is plausible that the main group pallasites originated from a Psyche-like parent body.