Известия Томского политехнического университета: Инжиниринг георесурсов (Aug 2017)
Singer carbonate technogenic mineral formations of the Tyra river embankment: development conditions, structure features and indication potential
Abstract
Relevance of the discussed issue. The study of technogenic mineral formation is one of the dynamically developing research directions of mineralogy and environmental geosciences. At present, one can observe a constant increase in the number of studies devoted to the mineral composition of formations of various natural-anthropogenic environments and technological systems: atmospheric dust aerosols, salt deposits of water and heat exchange equipment, etc. Formation of calcite singer bodies (stalactites, stalagmites and carbonate crusts) within different engineering structures due to carbonate leaching from cement matrix and their subsequent re-deposition is one of the most common types of technogenic minerogenesis. In modern scientific literature, the term «technogenic speleothems» is used to define this phenomenon. Technogenic speleothem formation is of interest not only as a practicable source of information on possible speeds and background of authigenic mineral formation, but also as a potential indicator of engineering structureґs functioning conditions, as well as to assess the quality of construction works and used building materials. The main aim of the research work is to study the morphology and microstructure of singer carbonate formations of the fourth level of the Tyra river embankment located within the Tyumen city to clarify the conditions of their formation and the possibility of their application to assess the functioning conditions of the engineering structure. The methods used in the research: macroscopic description, meseomorphological and microscopic studies of carbonate singer formations in thin sections, scanning electron microscopy, X-ray diffraction analysis. The results. Carbonate crusts and stalactite-like speleothems present the complex of carbonate singer forms examined within the fourth level of embankment. The results of microscopic studies confirm that carbonate singer forms are complicated structures and their development proceeds during several stages. Carbonate crusts are the long-term formations, while «stalactites» are the annual or quasiseasonal ones; that supports the high speed of their development. Growth of technogenic speleothems within the new engineering structure in uncharacteristic for this kind of formation conditions (well-blown, open space) indicates the high intensity of carbonates leaching from cement mortar used in the construction of the embankment. The detailed assessment of the scale of calcite dripstones formation on the surfaces of the embankment may be used for identifying the potential risks associated with long-term operation of the facility.
