Parauapebas meteorite from Pará, Brazil, a “hammer” breccia chondrite

Abstract

The Parauapebas meteorite, third official meteorite discovered in the Brazilian Amazon region, is a “hammer meteorite” which fell on December 9^th, 2013, in the city of Parauapebas, Pará State, Brazil. Mineralogy is dominated by forsterite, enstatite, iron, troilite, and tetrataenite. Albite, chromite, diopside, augite, pigeonite, taenite, and merrillite are minor components. Two main clasts are separated by black shock-induced melt veins. One clast exhibits an abundance of chondrules with well-defined margins set on a recrystallized matrix composed mostly of forsterite and enstatite, consistent with petrologic type 4 chondrites. The other clast displays chondrules with outlines blurring into the groundmass as evidence of increasing recrystallization, consistent with petrologic type 5 chondrites. The clasts of petrologic type 4 have a fine-grained texture compared to those of type 5. It is a genomict breccia (indicated by shock melt veins) with the clasts and matrix of the same compositional group, but different petrologic types, H4 and H5. The melted outer crust of the Parauapebas meteorite is comprised of forsterite with interstitial dendritic iron oxide, and is rich in irregular vesicles, which are evidence of the rapid formation of the crust. The type specimen is deposited in the Museum of Geosciences of the University of São Paulo, Brazil.

KEYWORDS:
Parauapebas; meteorite; chondrite; breccia; Brazilian meteorite