PNNL

Abstract

The meteorite Lieksa was found in 2017 in Löpönvaara, Finland, and later donated to the Finnish Museum of Natural History. Here, we report physical, chemical, and petrographic properties, siderophile element concentrations, and genetic isotopic data for the meteorite. Lieksa is ~80% metal and ~20% silicate and oxide inclusions by volume, with the inclusions consisting primarily of Fe-rich (Fa~25) olivine and aluminous and magnesian oxides. Due to Lieksa’s comparatively high silicate content, coupled with a texture characterized by metal enclosing the silicates, it has been classified as a pallasite. Lieksa’s olivine and bulk chemical characteristics are distinct from those of the known pallasite and iron meteorite groups, consistent with its classification as ungrouped. The meteorite exhibits a flat, chondrite-normalized highly siderophile element pattern, consistent with an origin as an early crystallization product from a metallic melt with chondritic relative abundances. Molybdenum, Ru, and 183W isotopic data indicate that Lieksa formed in the non-carbonaceous (NC) domain of the solar nebula. Radiogenic 182W abundances for Lieksa yield a model metal-silicate segregation age of 1.5 ± 0.8 Myr after calcium aluminum-rich inclusion formation, which is within the range established for other NC-type meteorite parent bodies.