The Zakłodzie enstatite meteorite: Mineralogy, petrology, origin, and classification

Abstract

The Zakłodzie meteorite was found in September 1998, about 40 km west of Zamość, in southeast Poland. Macroscopic and microscopic observations (in transmitted and reflected light), microprobe analyses, cathodoluminescence images, and X-ray diffraction data show that the meteorite is composed of clino- and orthoenstatite, two generations of feldspars, relict olivine (forsterite), a polymorph of SiO2 (apparently cristobalite), and opaque minerals: Fe-Ni alloy (kamacite and taenite), troilite, schreibersite, graphite, and sulfide (Mg, Mn, Fe)S, which is probably keilite. The texture is fine- to inequigranular of cumulate type, locally intergranular. The MgS-FeS thermometer indicates that the sulfides crystallized at ~580-600 ºC. Thus, the Zakłodzie meteorite formed by the nearly complete melting of an enstatite chondrite protolith, probably at ~4.4 Ga; the process was likely caused by the decay of the 26Al nuclide in the planetesimal interior. The second stage of its evolution, which could have happened at ~2.1 Ga, involved partial re-melting of most fusible components, probably due to collision with another body. The structure, composition, and origin of the meteorite and its relation to the parent rock indicate that Zakłodzie may represent a primitive enstatite achondrite.