Environmental Fate of Sulfur in Sulphur Creek, Valles Caldera, New Mexico: Natural Attenuation of Geothermal Components in Affected Watersheds
— Daniel J. Lavery, Laura J. Crossey, and Abdul-Mehdi S. Ali

The 1.23-Ma Valles Caldera in north-central New Mexico hosts a young (0.7 Ma to present day) igneous hydrothermal system
consistent with the model proposed in Goff and Janik (2000). The Sulphur Springs area within Valles Caldera is an acid-sulfate area typical
of this model, discharging acidic waters (pH 1.5–3) formed by oxidation at the surface of magmatic H2S. We report on samples obtained
from springs and streams collected between October 2021 and May 2023 in the Sulphur Creek and Alamo watersheds. Sulphur Creek
receives input from Sulphur Springs and exhibits low pH (2–4) and high concentrations of aluminum (≤110 mg/L) and sulfate (≤1,300
mg/L). These hydrothermal components are significantly attenuated by the downstream extent of the field area. This investigation uses
geochemical tracers such as major ions and stable and radiogenic isotopes to identify processes controlling attenuation. This research has
significance for the continued use of geothermally affected watersheds as water resources.