Abstract
Metallographic cooling rates have been determined for 12 iron meteorites of group IIIAB using the central taenite Ni content versus taenite width method. Experimentally determined values of local bulk Ni and P are included as input parameters in the calculations as outlined in Rasmussen (1982a, Icarus 52, 444–453). The calculations are based on the recently revised diffusivities and phase diagram recommended by Saikumar and Goldstein (1988, Geochim. Cosmochin. Acta 52, 715–726). The present results show no signs of undercooling in any of the meteorites investigated. The cooling rates are found to be constant through the group, supporting a core origin of group IIIAB. The average cooling rate for the group is found to be 49 K/my, corresponding to a parent body radius of 25 ± 7 km. An interpretation of the nucleation history reflecting the early impact history of the parent body is tentatively put forward.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
