Compositional and spectroscopic investigation of three ungrouped carbonaceous chondrites

YEŞİLTAŞ M., Kebukawa Y., Glotch T. D., Zolensky M., Fries M., AYSAL N., ...More

METEORITICS & PLANETARY SCIENCE, vol.57, no.9, pp.1665-1687, 2022 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 57 Issue: 9
  • Publication Date: 2022
  • Doi Number: 10.1111/maps.13893
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aerospace Database, Artic & Antarctic Regions, Chemical Abstracts Core, INSPEC
  • Page Numbers: pp.1665-1687
  • Istanbul University Affiliated: No


Ungrouped carbonaceous chondrites are not easily classified into one of the well-established groups due to compositional/petrological differences and geochemical anomalies. Type 2 ungrouped carbonaceous chondrites represent a very small fraction of all carbonaceous chondrites. They can potentially represent different aspects of asteroids and their regolith material. By conducting a multitechnique investigation, we show that Queen Alexandra Range (QUE) 99038 and Elephant Moraine (EET) 83226 do not resemble type 2 carbonaceous chondrites. QUE 99038 exhibits coarse-grained matrix, Fe-rich rims on olivines, and an apparent lack of tochilinite, suggesting that QUE 99038 has been metamorphosed. Its polyaromatic organic matter structures closely resemble oxidized CV3 chondrites. EET 83226 exhibits a clastic texture with high porosity and shows similarities to CO3 chondrites. It consists of numerous large chondrules with fine-grained rims that are often fragmented and discontinuous and set within matrix, suggesting a formation mechanism for the rims in a regolith environment. The kind of processes that can result in such chemical compositions as in QUE 99038 and EET 83226 is currently not fully known and clearly presents a conundrum. Tarda is a highly friable carbonaceous chondrite with close resemblance to Tagish Lake (ungrouped C2 chondrite). It comprises different types of chondrules (some with Fe-rich rims), framboid magnetite, sulfides, carbonates, and phyllosilicate- and carbon-rich matrix, and is consistent with being an ungrouped C2 chondrite.