Pasamonte eucrite: subsolidus thermal history

Primary and secondary textural and chemical relationships of HED meteorites are investigated to gain insight into the evolution of the HED parent body. Eucrites exhibit varying degrees of equilibration based on the extent of thermal metamorphism (types 1-6) [1] and type 7 [2]. A small percentage of eucrites have been identified as unequilibrated (types 1-3), based in part by the preservation of primary compositional zoning within pigeonite. Diffusion driven homogenization of the primary zoning within unequilibrated Pasamonte (Type 2) pyroxenes has been modeled to yield equilibrated bulk pyroxene compositions similar to what is observed in type-5 Juvinas pyroxene [3]. The focus of this investigation is to understand the post-magmatic Ca, Fe and Mg redistribution within the Pasamonte pyroxenes. This study is part of our ongoing study of the thermal and temporal conditions responsible for the equilibration of eucrite pyroxenes.