Earth’s Cryosphere, 2017, Vol. XXI, No. 4, p. 48-62
HIGHLY DYNAMIC ROCK GLACIERS OF TIEN SHAN
A.A. Galanin1,3, V.V. Olenchenko2, I.I. Khristoforov1, E.V. Severskiy1, A.A. Galanina3
1Melnikov Permafrost Institute, SB RAS, 36, Merzlotnaya str., Yakutsk, 677010, Russia; agalanin@gmail.com
2Institute of Petroleum Geology and Geophysics, SB RAS,
3, Acad. Koptyuga ave., Novosibirsk, 630090, Russia; olenchenkovv@yandex.ru
3Northeastern Federal University, 58, Belinskogo str., Yakutsk, 677000, Russia
A comprehensive study based on electrical resistivity tomography and GPR methods, geothermal monitoring and the stable isotopes analysis of glacial runoff has established that the most active frontal parts of Gorodetsky rock glacier in the Northern Tien Shan are thawed and substantially free of ground ice. The fast moving frontal parts of Gorodetsky rock glacier are composed of a mixture of coarsely fragmented debris, blocks of metamorphic ice and thixotropic sand- and clay-loamy filler. The input of fine-graded component from the glacial runoff infiltration and accumulates in the pores and voids of rock glacier, results in a gradual change in its physical properties (volume density, plasticity). Dynamics of such rock glaciers does not obey Glen’s law for viscous flow, and the presence of ground ice does not exert any significant effect on their inner deformations. Rheology models for such landforms can be based on the behavior of pseudoplastic (non-Newtonian) fluids and thixotropic systems. The lichenometry and Schmidt Hammer Test data provided a basis for establishing four different age generations of rock glaciers. These generations correlate well with Late Holocene oscillations of mountain glaciers in the Northern Tien Shan, which bears clear evidence of strong historical and genetic relationships between common glaciers and rock glaciers.
Rock glaciers, electrical resistivity tomography, ground penetrating radar, lichenometry, Schmidt Hammer Test, glacial mudflow, alpine permafrost, Tien Shan, Central Asia, Glen’s law