The research data are presented on the chemical and isotope composition of sodium bicarbonate groundwaters in the southeast of West Siberia. It is shown that the studied waters occur ubiquitously within Mesozoic–Cenozoic sedimentary deposits at a depth roughly from 50–300 m to 1.0–2.3 km. Various geochemical characteristics and conditions of occurrence made it possible to distinguish five types of waters: (I) fresh, (II) brackish, (III) high-alkaline low-saline, (IV) coal-deposit saline, and (V) carbonated waters. Types I and II are characterized by regional occurrence and a quite typical chemical composition. Types III–V have specific compositions and occur locally throughout the region. The genesis of all types of bicarbonate waters was determined as infiltration based on isotope data (δ18O, δD, and δ13С). Type IV is characterized by a positive “oxygen shift” and the carbon source is biogenic, except for type V. Calculations of equilibrium in the water-host minerals system showed that all bicarbonate waters were nonequilibrium for a number of primary aluminosilicate minerals and equilibrium for a wide variety of carbonates and clays. It was found that the amount of water-equilibrium minerals increased from type I to type IV with increasing water total dissolved solids (TDS) and pH values. The studies identified the governing characteristics of the formation of secondary minerals and hence of bicarbonate waters, including the main (pH value, Si, Ca, HCO3, and Al) and additional parameters of the medium (organic matter and gases). The same mechanism for all types of bicarbonate waters was determined: dissolution of water-nonequilibrium aluminosilicate minerals of sedimentary deposits and simultaneous precipitation of carbonates. The diversity of manifestations of bicarbonate waters is related to different interaction times in the water–rock system (types I and II), even during the bicarbonate stage, as well as additional overprinting of environmental features, i.e., the occurrence of supplementary sources of CO2 and organic matter for types IV and V, respectively, or their absence for type III. The presented formation schemes for different types of bicarbonate waters were also confirmed by the data of 18O and 13С isotope studies.

中文翻译：

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西西伯利亚东南部碳酸氢钠地下水的形成机制

研究数据提供了西西伯利亚东南部碳酸氢钠地下水的化学和同位素组成。结果表明，所研究的水域普遍存在于中、新生代沉积矿床中，深度大约为 50-300 m 至 1.0-2.3 km。各种地球化学特征和赋存条件使得区分五种类型的水成为可能：（I）淡水，（II）咸水，（III）高碱低盐，（IV）煤沉积盐，和（V）碳酸盐水域。Ⅰ型和Ⅱ型具有区域性产状和比较典型的化学成分特征。III-V 型具有特定的成分，并在整个地区局部发生。根据同位素数据（δ18O、δD 和 δ13С），所有类型的碳酸氢盐水的成因都被确定为渗透。IV 型的特征是“氧转移”为正，碳源是生物源的，除了 V 型。 水-宿主矿物系统中的平衡计算表明，所有碳酸氢盐水对于许多原生铝硅酸盐矿物都是非平衡的，而各种碳酸盐和粘土。发现随着水总溶解固体 (TDS) 和 pH 值的增加，水平衡矿物质的数量从 I 型增加到 IV 型。这些研究确定了次生矿物形成的控制特征，从而确定了碳酸氢盐水的形成，包括介质的主要参数（pH 值、Si、Ca、HCO3 和 Al）和其他参数（有机物和气体）。确定了所有类型的碳酸氢盐水的相同机制：沉积物的水-非平衡铝硅酸盐矿物的溶解和碳酸盐的同时沉淀。碳酸氢盐水表现形式的多样性与水-岩系统（I 型和 II 型）中不同的相互作用时间有关，甚至在碳酸氢盐阶段，以及环境特征的额外叠加，即 CO2 补充源的出现IV 型和 V 型有机物，或 III 型不存在。18O 和 13С 同位素研究的数据也证实了不同类型碳酸氢盐水的形成方案。即使在碳酸氢盐阶段，以及环境特征的额外叠印，即分别为 IV 型和 V 型出现 CO2 和有机物的补充来源，或在 III 型中不存在。18O 和 13С 同位素研究的数据也证实了不同类型碳酸氢盐水的形成方案。即使在碳酸氢盐阶段，以及环境特征的额外叠印，即分别为 IV 型和 V 型的 CO2 和有机物质的补充源的出现，或 III 型的无补充源。18O 和 13С 同位素研究的数据也证实了不同类型碳酸氢盐水的形成方案。