The Itoigawa UNESCO Global Geopark is located in Itoigawa City, Niigata Prefecture in central Japan. This geopark was approved as a Global Geopark in 2009, which is one of the first Global Geoparks in Japan. The Itoigawa–Shizuoka Tectonic Line, which divides the Japanese Islands into Southwest Japan and Northeast Japan in the Cenozoic tectonic framework, lies in the central part of the City of Itoigawa. Various rocks, ranging in age from the Cambrian to Quaternary, and cultural legacies can be observed in the 24 geosites in this geopark. Silurian, Permian, Triassic, and Jurassic radiolarians have been discovered from Itoigawa.
The 2nd International Symposium on Earth History of Asia was organized at Niigata, Japan, from 31 October to 3 November, 2014. The scientific session was held in Niigata University (Ikarashi Campus) on 31 October and 1 November, where a total of 126 scientists including 27 oversea ones from China, Korea, Taiwan, and India participated. The scientific session included 5 keynote talks, 9 invited talks, 13 oral presentations and 31 poster presentations. The program and abstracts of the scientific session was published in a supplement volume of Science Reports of Niigata University (Geology). The symposium also included a two-day field excursion in the Itoigawa Global Geopark. Activities of the excursion were, visits to three geosites, a tour of the Itoigawa City Museum of History and Folklore and a panel discussion at the Itoigawa City Hall. Sixty-one participants including earth scientists and local geopark mentors and tour guides joined the panel discussion. This symposium was conducted as part of the Niigata University Good Practice (GP) Program entitled “Formation of research and education hub for field geology in Asia-Oceania region” by the Faculty of Science from 2012 to 2014 fiscal years.
Morphological reexamination of the type specimems of Eosestheria sihetunensis from the Jianshangou beds, the lowest fossil bearing part of the Lower Cretaceous Yixian Formation in Sihetun Village of Beipiao City, western Liaoning Province, northeastern China under a scanning electron microscope (SEM) revealed morphological features on the carapace that had not been recognized previously: growth lines with fine ridges; growth bands near the umbo and in the middle part of the carapace are ornamented with reticulation, within which very fine ridges or cross bars and punta are observed; growth bands in the ventral part of the carapace ornamented with radial lirae, which expand to form triangularly enlarged structure.
The Sawando, Shimashima and Misogawa Complexs are exposed in the eastern part of the Mino Terrane. The Sawando and Misogawa Complexs are regarded to be formed by off-scraping accretion. On the other hand, the Shimashima Complex distributed between the Sawando Complex and the Misogawa Complex is considered to be formed by different processes. In this study, we intended to clarify whether the Shimashima Complex exists around the boundary between the Sawando Complex and the Misogawa Complex in the Kaida area, Nagano Prefecture. The study area is composed by the A, B and C formations. The A formation is dominated by siliceous rocks, forming an imbricate structure. Cherts in the A formation yielded radiolarian fossils indicative of the Middle Norian to Early Rhaetian. The B formation is dominated by sandstone and alternating beds of sandstone and mudstone. The C formation is dominated by mudstone. These lithologic features are similar to those of the Misogawa Complex. No geological unit similar to the Shimashima Complex in lithology has been found in the Kaida area.
