[M-IS12] Mountain Science

[MIS12-P07] Glacial fluctuation history of the Murodo-daira area during the Last Glacial Period: Evidence from a glacial geomorphological survey of Mount Murodo, Tateyama Mountains

*Mishina Haruka¹, Kotaro Fukui², Yusuke Suganuma^3,1, Jun'ichi Okuno^3,1, Takeshige Ishiwa^3,1, Tanaka Yasushi⁴ (1.The Graduate University for Advanced Studies, 2.Tateyama Caldera Sabo Museum, 3.National Institute of Polar Research, 4.Komazawa University)

Murodo-daira lava plateau in Tateyama Mountains is crucial for determining glacial fluctuation history through the relationship between volcanic deposits and glacial sediments. During the later phase of the last glacial period, glaciers covering Murodo-daira were thought to have originated from the former strato Volcano (Tateyama Volcano), which was located to the south of present Mt. Murodo-yama, Mt. Kunimi-dake, and Mt. Tengu-yama (Kawasumi, 2000). However, most of the Tateyama Volcano has since collapsed and eroded. This has created a huge oval depression, the Tateyama Caldera. The glacial landforms on the Tateyama Volcano during the last glacial period have disappeared except for a glacial trough lacking a cirque (Kobayashi, 1990). To better understand the glacial fluctuation history, we investigated small-scale glacial landforms, particularly roche moutonnées, using high-resolution drone-derived digital elevation models and orthoimages in Mt. Murodo-yama. Field surveys revealed that roche moutonnées are distributed along the Tamadono lava flow, oriented north to northwest, with glacial striations showing two distinct flow directions: northward and northwestward. These findings suggest that the glaciers on Mt. Murodo-yama alternated between northward flow toward the central of Murodo-daira lava plateau and northwestward flow during the Last Glacial Period. The glacier covering Murodo-daira lava plateau is thought to have originated from the northward flow. Future field studies will focus on establishing the temporal sequence of these two flow directions.

Kawasumi, T., Ages of Glaciations in the Early Stage of the Late Pleistocene, Based on Glacial and Volcanic Deposits in Tateyama, Hida Mountains, Central Japan. Geographical Review of Japan, 73A, 26-43, 2000.
Kobayashi, T., Tateyama Volcano and its glacial history in Toyama Prefecture. In The excursion guidebook, 97th Congress of the Geological Society of Japan, ed. Geological Society of Japan, 113-142, 1990.