Mineralogical examination of the Yamato-79 achondrites : Polymict eucrites and ureilites

• Main Authors: Hiroshi Takeda, Keizo Yanai
• Format: Report
• Language: English
• Published: Mineralogical Institute, Faculty of Science, University of Tokyo 1982
• Subjects: Antarctic; The Antarctic; Yamato; Antarc*; Memoirs of National Institute of Polar Research; Polar Research
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=1382; http://id.nii.ac.jp/1291/00001382/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=1382&item_no=1&attribute_id=18&file_no=1

Mineralogical examination of the first one-third of the Yamato-79 achondrites collected by the JARE party in 1979 and 1980 seasons revealed that eight of them are polymict eucrites similar to the Antarctic polymict eucrites reported previously, and that Y-790727 is a howardite and Y-790981 is a ureilite. The following Yamato-79 eucrites show features different from the known types. Y-790122 and Y-790266 are rich in lithic clasts. A thin section of Y-790122 consists of four different clast types joined together face to face with little matrix between them. Almost one-third of Y-790266 is a medium-grained subophitic basalt with pyroxene chemical zoning trends which simulate the host pigeonite and exsolved augite pair of the ordinary eucrites such as Juvinas. Y-790007 contains abundant cumulate eucrite clasts identical to Binda in their pyroxene exsolution texture and chemistry.