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Study on Triassic Smaller Foraminifers

三叠纪小型有孔虫研究

基本信息

批准号：
03454029
负责人：
IGO Hisayoshi
金额：
$ 2.05万
依托单位：
University of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1993
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-03454029/
关键词：
Triassic Smaller Foraminifer Mesozoic Microbiostratigraphy 微化石層序学有孔虫

项目摘要

Previous to our present research, Triassic foraminifers have not yet been studied in Japan. We tried to collect many Triassic smaller foraminifers from carbonate rocks exposed in various areas in Japan. As the result, we discovered many specimens of Triassic foraminifers from carbonate rocks exposed in Menashidomari, Hidaka mountains, and Kamiiso (Hokkaido), Ashio Mountains, Okutama area and other areas of the Kanto Mountains, Akasaka Limestone and other limestones in the Mino-Hida Mountains, the Taho and Kamura Limestones of Shikoku and Kyushu, and other small unnamed carbonate rock blocks elsewhere in Outer Zone of Japan. Our collections also contain many Triassic carbonate rocks of southern Thailand and northwestern Malaysia. Some materials were collected from the Pacific Side of North America.These specimens are thin-sectioned in preferred orientation and/or recovered as isolated specimens by acetic acid and hydrofluoric acid treatment and paleontologically studied. These indoor works are not completed but rapidly progressing. We checked most of the previously described Triassic foraminifers which were introduced mainly in European countries including Switzerland, Austria, Italy, and Burgaria. The examined specimens attain 486 species and synoptically listed for our future paleontological investigation.Up to date, we already discriminated about 50 species of Triassic foraminifersfrom the Schytian to Rhaetian. Some primitive type of ammodiscusid species are found even in dolomitic limestone of the Lower Triassic. The species and genera of Involutinidae and Ophthalminiinae are abundant and diversified in the Middle to Upper Triassic. Evolutional tendency of Triassic foraminifers show similar pattern with that of scleractinian corals and sponges.

在我们目前的研究之前，三叠纪有孔虫尚未在日本进行过研究。我们试图从日本不同地区的碳酸盐岩中收集许多三叠纪的小有孔虫。结果，我们在Menashidomari山、日高山和上矶（北海道）、芦尾山、奥玉地区和关东山脉的其他地区的碳酸盐岩中，在美浓飞田山的赤坂石灰岩和其他石灰岩中，在四国和九州的Taho和Kamura石灰岩中，以及在日本外带的其他地方，发现了许多三叠纪有孔虫标本。我们的收藏还包括泰国南部和马来西亚西北部的许多三叠纪碳酸盐岩。部分标本采自北美太平洋沿岸，经醋酸和氢氟酸处理后，取其薄片或分离标本进行古生物学研究。这些室内工程尚未完成，但进展迅速。我们检查了大多数先前描述的三叠纪有孔虫，这些有孔虫主要是在欧洲国家，包括瑞士，奥地利，意大利和Burgaria引进的。迄今为止，我们已经识别出了从Schytian到Rhaetian的三叠纪有孔虫约50种。甚至在下三叠统的灰岩中也发现了一些原始类型的沙盘虫。中、上三叠统卷蛾科和眼蛾亚科的种属丰富多样。三叠纪有孔虫的演化趋势与石珊瑚和海绵的演化趋势相似。