ANALYSIS OF THE CHELYABINSK METEORITE CONSTRAINING THE GEOLOGIC AND DYNAMICAL HISTORY OF THE PARENT BODY OF THE CHELYABINSK METEORITE

The Chelabinsk meteorite has three distinct lithologies and is categorized as an equilibrated ordinary (EOC) chondrite that is heavily shocked. It contains melt veins randomly distributed throughout. It is not known if the phases within the melt veins are 100% genetically related to the host phase or may have sampled an impactor that produced the shock feature. To determine the origins of the melt veins, we analyzed the host chondrite phases, olivine, pyroxene, and troilite as well as the phases within 7 melt veins with electron microprobe and compared their compositions. Our data confirm that the classification of the Chelyabinsk meteorite samples we investigated as LL5 chondrites. Our data for both major and minor elements from phases within the melt veins, confirmed the presence of olivine, pyroxene and troilite. The olivine compositions range from Fa₅₈ to Fo₆₄ and show enrichment in minor elements Ca, Co, Cr, Ni, S and Ti. There is clustering within the Ti content of olivines in the host rock, with some containing less that 0.02 wt% while others have greater than 0.10 wt%. Ti content within the melt veins is evenly spread within this same range of weight percentages. The olivine analysis also shows larger quantities of minor elements within the EOC samples compared to the melt rock. The pyroxenes within the samples range in composition of En₆₃ to Wo₅₁. The EOCs have notably higher calcium content and the lowest iron and magnesium content compared to melt rock samples. Troilite within the sample contains iron wt% ranging from 60 ~ 63% and sulfur 35~36%. We pose the following question: Is the composition of the melt veins dominated by the chemistry of the host chondrite or does it contain a geochemical signature of the impactor? We will explore the answer to this question with additional analyses, including oxygen isotopes.