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Re: Pallasites and Tatahouine
Kevin,
This may add a little to what Joel has told you.
The Eagle Station Trio consists of Eagle Station, Cold Bay, and
Itzawisis. Another related member is Bocaiuva. Only two pyroxene
pallasites have been recovered, Vermillion and Y8451, thus constituting
a grouplet of two. All the rest of the pallasites are in the main group
with a few pallasites being anamolous.
The pyroxene group has about 5% of its silicates as pyroxene or
orthopyroxene, where the main group has all olivine with only trace
pyroxenes. This may indicate a lower crystallization temperature of the
pyroxene grouplet. In addition, trace element and oxygen isotopic data
clearly resolve this group from the others.
The Eagle Station Trio grouplet contains high fayalite contents, high
Ge/Ga ratios in the metal, and a unique O-isotope composition. A high Ir
content suggests crystallization from the inner core region of its
parent body, below the core/mantle interface in which the main group
formed on its PB. The iron group IIIB may represent the core of the main
group PB. There were probably three separate PB's on which these
pallasite groups formed.
References: