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Abstract <p>The paper presents quantitative analyses (ICP-MS) of surface, snowmelt, and rainfall waters for 30&#xa0;elements and analyses of the bottom silts for 49 elements for mountain lakes in the Iolgo Range, Altai Mountains; and data on physicochemical characteristics of the water bodies (pH, redox potential (RP), and electrical conductivity). The surface waters are ultrafresh (mineralization (total dissolved solids, TDS) 5.7–43 mg/L) and slightly alkaline to alkaline (pH 7.6–9.0), and their RP corresponds to an oxidizing geochemical environment (166–225 mV). The water of all the lakes belongs to the calcic group. The predominant cations in the snowfield are Na, K, and Ca, and those in the rainfall are K, Si, and Ca. The characteristics of the water bodies are assumed as background ones for the territory. The content of pollutants does not exceed the maximum allowable concentration (MAC) in drinking water. The low concentrations of humic acids in the lean stony soils, long-lasting contact of the waters with Na-rich weathering products of the underlying sedimentary–volcanic rocks, and low CO<sub>2</sub> concentrations in the regional atmosphere are favorable for the formation of alkaline lake waters in the upper part of the Karakol valley. The main factors in the formation of the most alkaline and mineralized waters of all of the lakes studied in the upper Karakol valley are geochemical features of the bottom silts of these lakes and their stagnant nature, which facilitates the accumulation of elements over a long period of time. The lake silts inherit geochemical markers from the underlying volcanics, indicating the geodynamic setting of their formation. The PM-normalized multielemental patterns of the bottom silts show enrichment in LREE and LILE, depletion in HREE, and clearly discernible Nb, Ta, and Ti minima, which indicates that they contain weathering products of subduction-related rocks (which formed on an active continental margin). The study area is located within the Saganyy-Kylay Pb–Zn ore region with Pb and Cu ore occurrences and with W and Zn lithochemical anomalies. Elevated contents of these and associated metals are found both in the watercourses of the Tura and Ugul river basins and in the bottom silts of the lakes. Contents of Ni, Zn, and Pb in the surface waters and concentrations Be, V, Cu, Zn, Mo, W, and Pb in the lake silts exceed the Clarke values for lacustrine waters and the Earth’s crust, respectively, which corresponds to the metallogenic specifics of this region.</p>

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Hydrochemical and Lithochemical Features of Mountain Lakes in Areas of Ore-Bearing Sedimentary–Volcanogenic Rocks: A Case Study of the Karakol Lakes, Gorny Altai Mountains, South-Central Siberia

  • 期刊论文

  • 发表日期：

    2025年11月1日

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  • E. V. Borodina

摘要

Abstract

The paper presents quantitative analyses (ICP-MS) of surface, snowmelt, and rainfall waters for 30 elements and analyses of the bottom silts for 49 elements for mountain lakes in the Iolgo Range, Altai Mountains; and data on physicochemical characteristics of the water bodies (pH, redox potential (RP), and electrical conductivity). The surface waters are ultrafresh (mineralization (total dissolved solids, TDS) 5.7–43 mg/L) and slightly alkaline to alkaline (pH 7.6–9.0), and their RP corresponds to an oxidizing geochemical environment (166–225 mV). The water of all the lakes belongs to the calcic group. The predominant cations in the snowfield are Na, K, and Ca, and those in the rainfall are K, Si, and Ca. The characteristics of the water bodies are assumed as background ones for the territory. The content of pollutants does not exceed the maximum allowable concentration (MAC) in drinking water. The low concentrations of humic acids in the lean stony soils, long-lasting contact of the waters with Na-rich weathering products of the underlying sedimentary–volcanic rocks, and low CO2 concentrations in the regional atmosphere are favorable for the formation of alkaline lake waters in the upper part of the Karakol valley. The main factors in the formation of the most alkaline and mineralized waters of all of the lakes studied in the upper Karakol valley are geochemical features of the bottom silts of these lakes and their stagnant nature, which facilitates the accumulation of elements over a long period of time. The lake silts inherit geochemical markers from the underlying volcanics, indicating the geodynamic setting of their formation. The PM-normalized multielemental patterns of the bottom silts show enrichment in LREE and LILE, depletion in HREE, and clearly discernible Nb, Ta, and Ti minima, which indicates that they contain weathering products of subduction-related rocks (which formed on an active continental margin). The study area is located within the Saganyy-Kylay Pb–Zn ore region with Pb and Cu ore occurrences and with W and Zn lithochemical anomalies. Elevated contents of these and associated metals are found both in the watercourses of the Tura and Ugul river basins and in the bottom silts of the lakes. Contents of Ni, Zn, and Pb in the surface waters and concentrations Be, V, Cu, Zn, Mo, W, and Pb in the lake silts exceed the Clarke values for lacustrine waters and the Earth’s crust, respectively, which corresponds to the metallogenic specifics of this region.