Heterogeneous, rapid crystallization of the Main-Group pallasite parent body: Planetesimal history from principle component analysis of metal geochemistry and accessory phase mineralogies.

Pallasite meteorites comprise
olivine-metal mixtures and occur in a range of
textural types with numerous accessory phases such
as chromite, troilite, phosphide, phosphate and
phosphoran olivine [e.g. 1]. The petrogenesis of
pallasites has undergone considerable revision in
recent years [1,2,3], and their importance in
planetary differentiation is better understood with the
recognition of five separate parent bodies
[summarized in 1]. However, their formation
environment is still poorly constrained, with recent
suggestions including a quiescent core-mantle
boundary [1], a violent mixture of core and mantle
material [2], as well as a surface impact environment
[3]. In this paper, the evolution of the well-sampled
Main-Group pallasite parent body (source of
~90-95% of all pallasites) is re-evaluated using metal,
phosphate and other accessory phase geochemistry as
well as metallographic cooling rates.