Equilibrium and non-equilibrium condition of natural waters of northern part of Kolyvan-Tomsk folded zonewith leading minerals of enclosing rocks

This paper deals with the geochemical processes occurring in the water-rock system, anexample of natural waters north of Kolyvan-Tomsk folded zone. Administratively, the study area is located in the southeastern part ofWestern Siberia, within Tomsk region and occupies the Tom-Yaya interfluve. The material for the studies was the data of the problemhydrogeochemical research laboratory of the National Research Tomsk Polytechnic University in different years (1992-1993, 1998-2000and 2008). In the interpretation and generalization of the data chemical analyses of more than 1000 sample points were used, the study ofwhich showed that groundwater and surface water formed under these conditions are similar in composition, which is probably due to thepeculiarities of the chemical composition of underground waters of the Paleozoic basement that goes to the day surface and provides springfeed for rivers. Natural waters have mineralization of up to 800 mg/l (with the average of 500 mg/l) and pH - up to 8.2 and represent waterof leaching, whose formation is determined by the degree of their interaction with the surrounding aluminum silicates, which are mostdistributed in the study area among the water-bearing rocks. However, it should be noted that the majority of this fresh water is filled withcalcite, which makes the accumulation of calcium impossible for it, and transforms it into magnesium and in some cases - in sodium. Ourcalculations to study the equilibrium-non-equilibrium state of the system 'water - aluminosilicate minerals' have shown that all primaryaluminum silicates (anorthite, albite, forsterite, muscovite, potassium feldspar, etc.) are in non-equilibrium with the natural waters of thenorthern part of the Kolyvan-Tomsk folded zone and are able to be dissolved under these conditions with the formations of secondaryminerals (gibbsite, kaolinite, montmorillonite, illite, calcite, etc.). A significant part of the chemical elements coming into the solution due tothe incongruent dissolving of primary minerals is bound by secondary products, and the other part (the moving parts) concentrates in thesolution. In the formation of both groundwater and surface water the calcium component is formed due to leaching of carbonates and by thecalcium-containing feldspars (anorthite).The formation of calcium rather than sodium components dominant in the study area is due to theinteraction time in the water-rock system (i.e., the intensity of water exchange). The equilibrium of natural waters of the territory withendogenous minerals is impossible, because secondary minerals formed in this system are the geochemical barrier to such an equilibrium.

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