¹Mehmet Yesiltas,²Yoko Kebukawa,³Timothy D. Glotch,⁴Michael Zolensky,⁴Marc Fries,⁵Namik Aysal,⁵Fatma S. Tukel
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13893]
¹Faculty of Aeronautics and Space Sciences, Kirklareli University, Kirklareli, 39100 Turkey
²Faculty of Engineering, Yokohama National University, 240-8501 Yokohama, Japan
³Department of Geosciences, Stony Brook University, Stony Brook, New York, 11790 USA
⁴Astromaterials Research and Exploration Science, Johnson Space Center, NASA, Houston, Texas, 77058 USA
⁵Department of Geological Engineering, Istanbul University-Cerrahpasa, Istanbul, 34320 Turkey
Published by arrangement with John Wiley & Sons

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.