Isotopic geochemistry of the Saratoga springs: Implications for the origin of solutes and source of carbon dioxide

We report the results of an isotopic study designed to determine the source of solutes and carbon dioxide in the famed Saratoga Springs (New York) mineral waters. These waters have thousands of milligrams per liter total dissolved solid concentrations and are highly charged with carbon dioxide gas. The spring waters are cold (∼12 °C) and there is no local, deep-seated thermal anomaly. They emerge through thick shale caprock along the surface expression of normal faults. The δ¹³C (-5.8‰ to +0.8‰ Vienna Peedee belemnite) of the dissolved inorganic carbon and elevated ³He/⁴He ratios suggest that the source of the CO₂ is the mantle or an ancient deep crystallized igneous melt. The stable isotopic content of the spring waters defines a mixing line between modern local meteoric waters (δ ∼ 70‰) and a component with heavier δD but similar δ¹⁸O values. This trend and that of ⁸⁷Sr/⁸⁶Sr of dissolved strontium versus 1/Sr are consistent with the hypothesis that Canadian Shield-type brines contribute salinity to the springs. These brines plausibly migrate from the Adirondack Mountains to the topographically low McGregor fault system in the Hudson River lowlands, where the Saratoga springs discharge.