Petrology and classification of new Antarctic carbonaceous chondrites PCA-91082, TIL-91722 and WIS-91600

• Main Authors: Birjukov,Vladislav V., Ulyanov,Alexander A.
• Format: Report
• Language: English
• Published: Division of Mineralogy, Geological Department of M.V. Lomonosov, Moscow State University/Division of Mineralogy, Geological Department of M.V. Lomonosov, Moscow State University 1996
• Subjects: Antarctic; Pecora Escarpment; Thiel Mountains; Wisconsin Range; Antarc*
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=4697; http://id.nii.ac.jp/1291/00004697/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=4697&item_no=1&attribute_id=18&file_no=1

Three Antarctic chondrites : Pecora Escarpment (PCA) 91082,Thiel Mountains (TIL) 91722 and Wisconsin Range (WIS) 91600 were studied by SEMEDS methods and classified as CR2,CV3 and CM2,respectively. PCA91082 and TIL91722 contain rare fine-grained refractory inclusions and amoeboid olivine aggregates without any traces of secondary alteration processes. Chondrule pyroxene is enriched in Cr and Mn compared to pyroxenes from refractory inclusions. Presence of Cr^<2+> and Ti^<3+> with normal Cr^<3+> and Ti^<4+> in chondrule pyroxenes probably indicates reducing conditions during chondrule formation. Several unusual objects, such as a compound P-rich chondrule in PCA91082,and P and Cr enriched glasses in WIS91600,were studied. The metal fraction of PCA91082 shows a positive Nivs. Co trend which can be produced by volatilization process. Bulk composition of inclusions and chondrules follows to condensation trend, but exsolution structures and glasses indicate crystallization from melts.