Study of latest Cretaceous Radiolarian Assemblage and the faunal change in northern Japan

日本北部白垩纪最新放射虫组合及动物区系变化研究

• 批准号: 62540592
• 负责人: IWATA Keiji
• 金额: $ 0.7万
• 依托单位: Hokkaido University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1987
• 资助国家: 日本
• 起止时间: 1987 至 1988
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-62540592/
• 关键词: Hakobuchi Group; Hidaka Supergroup; Yubetsu Group; Nemuro Group; Upper Cretaceous; Radiolarian Biostrtigraphy; 化石群集変遷; 化石分帯; 分帯

The authors investigated especially the radiolarian biostratigraphy of the Hakobuchi Group of Nakatonbetsu region in the northern Hokkaido. As a result, two radiolarian zonations of the latest Cretaceous System - Protoxiphotractus perplexus zone (early - middle Campanian) and Chlathrocyclas gravis zone (late Campanian - early Maastrichtian) were established. The former zone corresponds to Amphipyndax enesseffi zone and the latter corresponds to Amphipyndax tylotus zone of the Upper Cretaceous in the Tropical Pacific Oceans and the southwestern Japan. The fanual difference between the Hakobuchi Group and the Hidaka Supergroup was distinguished. Namely, amphipyndax enesseffi and A. tylotus assemblage were found in the Hidaka Supergroup, but these assemblages were completely absent in the Hakobuchi Group. Faunal difference among the Hakobuchi Group, Hidaka Supergroup, and the Upper Cretaceous Systems in the southwestern Japan suggests differences of paleogeography and accumulation sites of sediments9 Abrupt decline of late Cretaceous radiolarians was detected in the Hakobuchi Group, but some genera of Cretaceous type persist into the early Paleocene epoch.

作者重点研究了北海道北方中屯别地区箱渊群的放射虫生物地层。据此，建立了晚白垩世的两个放射虫分带-- Protoxiphotractus perplexus带（早-中Campanian）和Chlathrocyclas gravis带（晚Campanian -早Maastrichtian）。前者与Amphipyndax enesseffi带相对应，后者与热带太平洋和日本西南部晚白垩世的Amphipyndax tylotus带相对应。区分了箱渊群与日高超群的季节差异。enesseffi和A.在日高超群中发现了tylotus组合，但在箱渊群中完全没有这些组合。日本西南部箱渊群、日高超群和上白垩统之间的动物群差异表明了古地理和沉积物聚集地点的差异。

项目成果

Kato, Yukihiro; Iwata, Keiji: "Radiolarian biostratigraphic study of the pre-Tertiary System around the Kamikawa Basin, central Hokkaido, Japan" Journal of Faculty of Science, Hokkaido University. (1989)

加藤幸弘；

岩田圭示: HSGニュースレター. 3. 9-10 (1988)

岩田敬二：HSG 通讯。3. 9-10 (1988)

IWATA,Keiji and TAJIKA,Jun: Jour.Fac.Sci,Hokkaido University.

IWATA，Keiji 和 TAJIKA，Jun：Jour.Fac.Sci，北海道大学。

Watanabe, Yasushi; Iwata, Keiji: "The Hidaka Supergroup in the Tomuraushi region, Hidaka Belt, Hokkaido, Japan" Earth Science. 41. 35-47 (1987)

渡边靖；

Iwata, Keiji: "Radiolarian Biostratigraphy of the Hakobuchi Group in the Nakatonbetsu region ( preliminary report )" HSG Newsletter. 3. 1-8 (1988)

岩田敬二：“中顿别地区箱渊群放射虫生物地层学（初步报告）”HSG 通讯。