Prepared in cooperation with the Bureau of Land Management Geochemical Characterization of Groundwater Discharging from Springs North of the Grand Canyon, Arizona, 2009–2016 Scientific Investigations Report 2017–5068 U.S. Department of the Interior U.S. Geological Survey Cover. Water resource in Tuckup Canyon, Arizona, downgradient of Cottonwood Spring as seen by helicopter in August 2009, photo by Donald J. Bills. Geochemical Characterization of Groundwater Discharging from Springs North of the Grand Canyon, Arizona, 2009–2016 By Kimberly R. Beisner, Fred D. Tillman, Jessica R. Anderson, Ronald C. Antweiler, and Donald J. Bills Prepared in cooperation with the Bureau of Land Management Scientific Investigations Report 2017–5068 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior RYAN K. ZINKE, Secretary U.S. Geological Survey William H. Werkheiser, Acting Director U.S. Geological Survey, Reston, Virginia: 2017 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment—visit https://www.usgs.gov or call 1–888–ASK–USGS. For an overview of USGS information products, including maps, imagery, and publications, visit https://store.usgs.gov. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. Suggested citation: Beisner, K.R., Tillman, F.D., Anderson, J.R., Antweiler, R.C., and Bills, D.J., 2017, Geochemical characterization of groundwater discharging from springs north of the Grand Canyon, Arizona, 2009–2016: U.S. Geological Survey Scien- tific Investigations Report 2017–5068, 58 p., https://doi.org/10.3133/sir20175068. ISSN 2328-0328 (online) iii Acknowledgments The geochemical investigation presented in this report was supported by the U.S. Geological Survey (USGS) Toxic Substances Hydrology Program and the Bureau of Land Management. The report benefitted greatly from input from James Paces and Nick Paretti. iv Contents Acknowledgments ........................................................................................................................................iii Abstract ...........................................................................................................................................................1 Introduction.....................................................................................................................................................1 Purpose and Scope ..............................................................................................................................2 Study Area..............................................................................................................................................2 Geologic Setting ...........................................................................................................................2 Breccia Pipe Formation and Geochemistry ............................................................................4 Radioisotope Geochemistry .......................................................................................................5 Groundwater Occurrence and Movement ..............................................................................5 Climate ...........................................................................................................................................6 Methodology ...................................................................................................................................................6 Field .........................................................................................................................................................6 Analytical................................................................................................................................................6 Quality Assurance.................................................................................................................................7 Laboratory Selection ...................................................................................................................7 Data Analysis .........................................................................................................................................8 Results .............................................................................................................................................................9 Quality Assessment ..............................................................................................................................9 Environmental Samples .....................................................................................................................11 Parameters and Major Ions .....................................................................................................11 Trace Elements ...........................................................................................................................13 Multivariate Analysis .......................................................................................................31 Isotopic and Radioactivity Analysis ........................................................................................35 Radiochemistry...........................................................................................................................35 Strontium Isotopes ...........................................................................................................35 Oxygen and Hydrogen Stable Isotopes .........................................................................40 Groundwater Ages ....................................................................................................................41 Carbon-14 ...........................................................................................................................41 Tritium ................................................................................................................................41 Discussion .....................................................................................................................................................48 Evidence for Water Rock Interaction with Implication for Flowpaths .......................................48 Springs with Elevated Uranium and Selenium Concentrations ..................................................49 Springs with a Possible Component of Geothermal Fluids ..........................................................52 Conclusions...................................................................................................................................................52 References Cited..........................................................................................................................................52 Appendixes 1–6 ............................................................................................................................................58 v Figures 1. Map of study area with uranium mining withdrawal areas and spring sample locations identified by the geologic unit they discharge from ..............................................3 2. Schematic of breccia pipe ..........................................................................................................4 3. Graph of uranium activity ratio values from the U.S. Geological Survey National Research Program Lab versus USGS contract labs. ............................................................11 4. Box plots of temperature, pH, and specific conductance ...................................................12 5. Box plots of major cation concentrations; calcium, magnesium, potassium, and sodium ...................................................................................................................................14 6. Box plots of major anion concentrations; bicarbonate, chloride, fluoride, and sulfate ...................................................................................................................................15 7. Piper plot representing major ion composition for spring samples. ..................................16 8. Maps of trace element concentration for arsenic, selenium, and uranium from spring samples ..................................................................................................................17 9. Box plots of trace element concentrations ............................................................................21 10. Box plots of trace element concentrations grouped by geologic unit of spring discharge .........................................................................................................................26 11. Nonmetric multidimensional scaling plot for spring samples with polygons outlining geologic unit of spring discharge ............................................................................32 12. Correlogram including the Kendall’s tau value for elemental pairs, where values with an X are not statistically significant with p >0.05 .............................................33 13. Cluster dendrogram for spring samples .................................................................................34