Chemical composition of natural waters of the eastern rim of the Siberian platform (Predverkhoyansk foredeep)

Abstract

Relevance. Foothill (foredeep, pericratonic) deflections play a significant role generation and localization of hydrocarbon accumulations and are promising objects of oil and gas exploration. Numerous studies of such structures are focused mainly on the geological structure, formation and prospects of oil and gas potential of these territories. Issues related to the geochemistry of natural waters are either not covered at all, or are presented in an extremely limited form. Studying the chemical composition of the natural waters of the Predverkhoyansk foredeep at the modern analytical level will make it possible to assess the hydrogeochemical background and emphasize the peculiarities of the behavior of the main components of the aquatic environment in conditions of a sharp change in the tectonic situation. Aim. To study and identify the hydrogeochemical features of the composition of natural waters in the area of the eastern framing of the Siberian platform in the region of its junction with the scaly-thrust dislocations of the Verkhoyano-Kolyma folded zone. Methods. Measurements of rapidly changing parameters of natural waters (pH, Eh, temperature) were carried out directly at the sampling site with a portable HQ-40D analyzer from Hach Lange (USA). The analysis of the chemical composition of waters was carried out in the Problematic Research Laboratory of Hydrogeochemistry of Tomsk Polytechnic University using ion chromatography methods on a two-channel reagentless ionochromatographic complex ICS-5000 with conductometric detection manufactured by Dionex-Thegmo Scientific (USA). The content of CO32– and HCO3–anions in the studied waters was determined by the traditional titrimetry method for these indicators. The Si concentration was determined by inductively coupled plasma mass spectrometry on a NeXION 300D device, Perkin Elmer (USA). Results. The paper presents the data on the chemical composition of the natural waters of the Tompo, Lyapiske, Sobolokh-Mayan (Sobopol) river basins in the inner part of the Predverkhoyansk foredeep in front of the cutting edge of the advanced thrust of the western slope of the Verkhoyansk anticlinorium. The patterns of the distribution of basic ions are shown, common features and differences between the studied sites are revealed.

Keywords

• Predverkhoyansk foredeep
• chemical composition of natural waters
• hydrogeochemical features
• major ions
• Siberian platform