Hydrogeododynamic processes in carbonate rocks. Part I. Suffosion

Abstract

Problem statement. Groundwater is an active factor in geodynamic processes, giving rise to such phenomena as suffusion and karst of carbonate rocks. These processes pose one of the greatest threats to buildings and structures and occur predominantly under the influence of infiltration waters, the horizons and complexes of which are in the near-surface, broken part of the lithosphere.

Groundwater is characterized by two main types of geological activity - physical (mechanical) and chemical (soluble), which, accordingly, causes the development of such geodynamic processes as suffosion and karst in carbonaceous rocks. Very often both mechanical and chemical groundwater activities occur simultaneously. Therefore, determining the role of each of these processes in the destruction of carbonate rocks requires field observations, laboratory studies and theoretical substantiation.

Object matter of the research. The object matter of the study is the marl and chalk rocks of the Upper Cretaceous, which are exposed in the southern wing of Svyatohirs’k brachyanticline in the form of "Cretaceous boulder". This structure is separated by the zone of the Petrivs’k-Kreminna deep fault, along which flows the river Siversky Donets.

The subject matter of the research is the suffosion in the carbonate marl and chalk rocks of the upper chalk.

Presentation of the main material. The geological, hydrogeological and geomorphological features of Svyatohirs’k brachyanticline in connection with the development of suffosion processes are considered. On the basis of the factual material obtained in the course of field studies, it is shown that physical destruction of the rocks, referred to as suffusion, occurs in the carbonate marl and cretaceous strata of the upper chalk. The possibilities of determining the quantitative indicators of "solid runoff" that is formed during the transfer of solid mineral matter by the underground waters are described. It is established that the intensity of suffusion is directly dependent on the volume of infiltration water in different periods of the year and the geomorphological features of the territory.

The most recent and present-day tectonic activation of the Petrivs’k-Kreminna fault promotes the development of suffosion, which causes not only the raising of the southern wing of Svyatohirs’k brachyanticline, but also the disintegration of carbonate marl and cretaceous rocks of the upper chalk. The ascendant tectonic development of the relief is associated with arching slopes, which substantially dominate the "Cretaceous boulder" relief. This is due to an increase in the energy potential of denudation processes and, consequently, an increase in the influence of infiltration water flows on the carbonate rocks of the weathering zone and the intensification of suffusion. It is substantiated that at a certain stage of the development of the suffusion process there is observed a shift from quantitative changes, connected with the ever larger fragmentation of carbonate rock particles, to qualitative - physical (suffosion) processes to the chemical (karst).

Conclusions. It is shown that groundwater is an active factor in geodynamic processes in carbonate rocks, which bring about suffosion and karst. Suffosion is the result of the physical activity of groundwater, in which rocks are mechanically (physically) destroyed with the formation of "solid runoff". The most important indicator of the intensity of suffosion is the module of "solid runoff", which depends on the climatic, geomorphological and geological features of the territory. This process is also correlated with the seasons of the year and the manifestations of modern and modern tectonics, which determines the directions of relief development. The development of suffosion processes is accompanied by increasingly more intense shredding of carbonate rocks (up to suspensions). Under certain physical and chemical conditions, this causes the transition of quantitative changes in the system "carbonate rocks - underground waters" into qualitative - physical (suffosion) processes into the chemical (karst).