TECTONOGENIC HYDROGEOLOGIC PHENOMENA IN THE TALIK OF A LOW-ORDER WATERCOURSE
V.M. Mikhailov
Melnikov Permafrost Institute, Siberian Branch of the Russian Academy of Sciences, North-Eastern Permafrost Research Station, Magadan, Russia
Keywords: permafrost, taliks, hydrogeologic processes, evolution of waterbodies, small-block tectonics, surface-groundwater relationship, retrospective analysis
Abstract
Landscape-hydrological and hydrogeological changes have been studied in a second-order creek valley with water recharge taliks formed along two linear faults and an isometric depression closing the lower fault. A hypothesis about the tectonic origin of these changes is advanced based on the analysis of aerospace materials, in situ observations, and reference data. At least until 1965, there was no runoff in the valley downstream of the depression, and the maximum water infiltration rate exceeded 4 m3/s. Surface water infiltration, together with the deposition of sediment load, took place mainly in the depression. Subsequently, both processes virtually stopped there because of the rise of the bottom of the depression relative to the valley thalweg, and a fully developed channel was shaped downstream. Surface water infiltration has decreased by more than an order of magnitude and is observed now mainly in the area of linear faults. In the depression, it occurs sporadically at its margin, where a tectonic ditch is perpendicular to the creek channel. The ongoing tectonic activity may cause high intensity of water intake, up to the spontaneous discharge of the channel flow. In the observed case, such a discharge flow developed in the channel in the direction opposite to the slope of the creek thalweg. Such spontaneous phenomena cannot be explained within the framework of modern concepts about the minimum size of mobile tectonic blocks and attest to the need for their revision.
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