Ekaterina LEBEDEVA, ,
Sergey KHARCHENKO, ,
Nadine ANIKINA, ,
Alexey KOTENKOV , ,
The influence of the processes of caldera formation, the growth of extrusive massifs and the nature of rocks on the formation of valleys is considered on the example of the Geysernaya, Ozernaya and Teplaya rivers, which are located within the Eastern volcanic belt of the Kamchatka Peninsula. The location of river valleys is due to the position of the faults and is closely related to the Late Pleistocene-Holocene caldera formation. The processes of caldera formation determined the peculiarities of the planned pattern, structure and re-formation of river valleys, the nature of their longitudinal profile, and the morphology of the sides of erosion incisions. The presence of numerous extrusive massifs inside calderas and on their sides additionally increased the influence of the structural factor on the development of valleys: both passive (outcrops of erosion-resistant rocks) and active - the formation of (1) landslides (deep incision of rivers stimulated the collapse of the edges of extrusions with the formation of extensive landslides bodies) and (2) debris avalanches (caused by the growth of extrusions – according to Ponomareva et al., 2006). Interferometric data (Lundgren and Lu, 2006) indicate the presence of separate areas of modern uplift of the territory (for example, the left side of the Geysernaya R. valley), which is associated with the position of the magma chamber of the Kikhpinych volcano (Kiryukhin et al., 2012). The uplift stimulates the activation of slope processes on the adjacent side of the valley. The lithological properties of the rocks of this basin were also significantly influenced by gas-hydrothermal processes, which led to weathering rocks to clays in fault zones (Frolova et al., 2011) and to increase the rate of erosion and denudation there. The generalization of materials was supported by the grant of the RSF No. 21-17-00216.
Keywords: caldera|extrusion|river valley|slope processes|weathering