A global carbon-isotope event in the Middle Turonian (Cretaceous) sequences in Japan and Russian Far East

• Published in: Proceedings of the Japan Academy, Series B
• Main Authors: Hasegawa Takashi, 長谷川 卓
• Format: Article in Journal/Newspaper
• Language: English
• Published: 日本学士院 2003
• Subjects: Biostratigraphy; Carbon isotope; correlation; Collignoniceras; Cretaceous; Hokkaido; Inoceramus; Sakhalin
• Online Access: http://hdl.handle.net/2297/10558; https://kanazawa-u.repo.nii.ac.jp/?action=repository_uri&item_id=10151; https://kanazawa-u.repo.nii.ac.jp/?action=repository_action_common_download&item_id=10151&item_no=1&attribute_id=26&file_no=1

金沢大学理工研究域理工研究域地球社会基盤学系 A time-diagnostic positive excursion (∼1‰) of carbon isotope ratio (δ13C) recorded in organic matter from the Middle Turonian (Late Cretaceous) clastic sequences in Japan and Russian Far East provides inter-regionally recognizable chemostratigraphic keybed at 90.7 Ma. Compilation of recent studies on carbon-isotope stratigraphy for this region revealed that the δ13C event, is located in the middle of gradual ∼1.5‰ negative shift above the prominent Cenornanian/Turonian boundary δ513C "spike". Limited occurrences of cosmopolitan age-indicative ammonoid species, Collignoniceras woollgari revealed that the range of this species encompasses the δ13C event horizon confirming its utility as an international chemostratigraphic keybed, whereas the common occurrence of Inoceramus hobetsensis across the δ13C event benefits identifying this important marker horizon.