Alteration of chondrules and matrices in the four Antarctic carbonaceous chondrites ALH-77307 (C3), Y-790123 (C2), Y-75293 (C2), and Y-74662 (C2)

• Main Author: Ikeda, Yukio
• Language: English
• Published: 1983
• Subjects: Antarctic; Antarc*; Memoirs of National Institute of Polar Research; Polar Research
• Online Access: https://nipr.repo.nii.ac.jp/record/1554/files/KJ00000012187.pdf

P(論文) Alteration products of the groundmasses in chondrules of the C chondrites ALH-77307,Y-790123,Y-75293,and Y-74662 consist mainly of chlorite (and/or berthierine) containing high Al_2O_3 contents, and those of the matrices are mainly serpentine with minor amounts of Al_2O_3 contents. This difference reflects that of their precursor materials prior to the alteration. The degrees of chondrule alteration are various within a chondrite and among the four chondrites studied, and are classified into four stages (I, II, III, and IV ranging from weak to intense alteration) according to petrographic criteria. Most chondrules in ALH-77307 are stage II, and those in Y-74662 are stage III. Y-790123 and Y-75293 include the chondrules of stages II and III. The alteration of chondrules and matrices took place prior to the final agglomeration of these chondrites. departmental bulletin paper