Most carbonaceous (C) chondrites are classified into eight major groups: CI, CM, CO, CV, CK, CR, CH, and CB. However, some are ungrouped. We studied two such chondrites, Asuka (A)-9003 and A 09535. The abundance of chondrules and matrix and chondrule sizes in these meteorites are similar to those in ordinary chondrites and unlike any known carbonaceous chondrite group. In contrast, they contain 4–6 vol% of refractory inclusions and have oxygen isotopic compositions within the range of CO and CV chondrites. Therefore, A-9003 and A 09535 are classified as C chondrites. Petrologic subtypes of A-9003 and A 09535 are 3.2. All these features closely resemble those of another ungrouped chondrite, Yamato (Y)-82094, and differ from those of any C chondrites reported by now. A-9003, A 09535, and Y-82094 likely represent a new type of C chondrite. We provisionally call them CA chondrite after Asuka in Antarctica. Our study suggests a wider range of formation conditions for C chondrites than currently recorded by the major C chondrite groups.

中文翻译：

---

A-9003、A 09535 和 Y-82094 的岩石学和分类：一种新型碳质球粒陨石

大多数碳质 (C) 球粒陨石分为八类：CI、CM、CO、CV、CK、CR、CH 和 CB。但是，有些是未分组的。我们研究了两种这样的球粒陨石，Asuka (A)-9003 和 A 09535。这些陨石中的球粒陨石和基质以及球粒陨石尺寸的丰度与普通球粒陨石相似，并且不同于任何已知的碳质球粒陨石群。相比之下，它们含有 4-6 vol% 的难熔包裹体，并且氧同位素组成在 CO 和 CV 球粒陨石的范围内。因此，A-9003 和 A 09535 被归类为 C 球粒陨石。A-9003 和 A 09535 的岩石学亚型为 3.2。所有这些特征都与另一个未分组球粒陨石大和 (Y)-82094 的特征非常相似，并且与目前报道的任何 C 球粒陨石的特征都不同。A-9003、A 09535 和 Y-82094 可能代表一种新型 C 球粒陨石。在南极洲的明日香之后，我们暂时称它们为 CA 球粒陨石。我们的研究表明 C 球粒陨石的形成条件比目前主要 C 球粒陨石组记录的范围更广。