[A-CC25] Glaciology in the new normal

[ACC25-07] The formation environment of glacier-derived rock glacier in the Tien Shan, Central Asia

*Shun Okuyama¹, Chiyuki Narama², Akiko Yamamura³, Hideyuki Takadama⁴, yamanokuti Tsutomu⁵ (1.Graduate Student,Niigata Univ., 2.Niigata Univ., 3.Aero Asahi Co., 4.PASCO Co., 5.Remote Sensing Technology Center of Japan)

Keywords:rock glacier, mountain permafrost, glacier, DInSAR, Tien Shan

Rock glacier is composed of permafrost mixed with ice and debris, and flows by deformation of internal ice as well as glacier. The formation of rock glacier requires climatic constraints such as temperature and precipitation, mechanical constraints such as the supply of debris from the rock wall behind the glacier, and the existence of a debris deposit site at the base of the rock wall (Barsch, 1992; Ikeda and Yoshikawa, 2008). Rock glaciers are classified into "talus-derived type" and "glacier-derived type" based on the difference in the source of debris and internal ice (Matsuoka, 1998). The "talus-derived type" is a type in which residual snow or underground water becomes a source of permafrost, and develops on the cliff formed by gravel supplied from the bedrock behind it. The "glacier-derived type" is a type in which a glacier exists superior of a rock glacier, and develops from glacier ice and meltwater from the glacier. The distribution of "glacier-derived type" rock glaciers is limited, and its development process is not clear. Study area is unique in that "glacier-derived type" rock glacier account for about 60% of all rock glacier. In this study, we attempted to clarify the spatial distribution and formation conditions of "glacier-derived type" rock glacier in the Kyrgyz Range in the northern Tien Shan Mountains using satellite image analysis.