Diopside in chondrules of Yamato-691 (EH3)

• Main Authors: Masao Kitamura, Seiko Watanabe, Hiroshi Isobe, Nobuo Morimoto
• Format: Report
• Language: English
• Published: Department of Geology and Mineralogy, Faculty of Science, Kyoto University/Department of Geology and Mineralogy, Faculty of Science, Kyoto University/Department of Geology and Mineralogy, Faculty of Science, Kyoto University/Department of Geology and Mineralogy, Faculty of Science, Kyoto University 1987
• Subjects: Yamato; Memoirs of National Institute of Polar Research; Polar Research
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=2125; http://id.nii.ac.jp/1291/00002125/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=2125&item_no=1&attribute_id=18&file_no=1

Diopside in the chondrules in Y-691 (EH3), most of which include enstatite as phenocrysts, occurs in three different modes; (1) diopside rimming some of the enstatite crystals, (2) single crystals as phenocrysts of the chondrules, and (3) single crystals of diopside enriched in aluminum in one chondrule. The finding of the single crystals of diopside, since that in Qingzhen, indicates their common existence in the E3 chondrites. Common appearance of the single crystals, in contrast with the equilibrated E and the unequilibrated ordinary chondrites, is considered to be related with the reducing condition during the chondrule formation. Crystallization temperature of the crystals is roughly estimated to be 1300-1200℃. Coexistence of aluminum-rich and aluminum-poor diopside in a chondrule implies high pressure episode by shock process.