In most studies of the environmental effects of mineralization and alteration, sampling is limited to surface waters and springs. Our current understanding of deep bedrock groundwater circulation in mineralized mountain blocks is limited due to a lack of deeper monitoring wells (> tens of meters depth) that allow direct, high-quality hydrogeologic observations. Even though bedrock groundwater discharge may be a relatively small component of the annual surface water budget, the conribution of metal loads may be disproportionately large due to higher concentrations of metals in the groundwater. Additionally, most existing studies of mountain groundwater flow have been carried out in crystalline rocks, which are not reflective of some Colorado mineralized mountain watersheds.
Our research augments ongoing research efforts in the upper East River watershed near Crested Butte, CO, performed under Lawrence Berkeley National Laboratory Watershed Function Science Focus Area, which primarily focuses on surface water and shallow alluvial groundwater systems. Our primary research objectives are: (1) to understand the deep bedrock groundwater circulation system in a mineralized watershed and the subsequent flux of metals to the surface that results as the groundwater discharges; and (2) to compare how these hydrologic and geochemical fluxes vary between mineralized and unmineralized catchments in the Mt. Emmons and upper East River areas. We will conduct our research in a mountain block composed primarily of a thick package of sedimentary rocks and combine geophysical, hydrologic, geochemical, and isotopic methods with geological and borehole data to accomplish our objectives. Our emphasis on intertwining geology, geophysics, and geochemistry is necessitated by the inherent complexity of hydrogeochemical systems in mineralized mountain blocks. By meeting these objectives we will gain a broader understanding of the hydrogeochemistry of mineralized mountain watersheds, and the hydrogeologic significance of hydrothermal alteration in sedimentary bedrock watersheds.
Central Mineral and Environmental Resources Science Center
Crustal Geophysics and Geochemistry Science Center