Geochemistry and Environmental Tracer Data for Groundwater, Stream Water, and Ferricrete Samples from Handcart Gulch, Colorado

This data release is part of a study examining the use of near-stream groundwater discharge as a tool for Geochemical Exploration. Handcart Gulch is an unmined alpine watershed in Montezuma Mining District in the Colorado Front Range. The streambed is cemented by deep ferricrete deposits. Stream water, groundwater, and ferricrete samples were collected and analyzed to constrain the location of a possible concealed mineral occurrence identified by previous stream water sampling. Nineteen, near stream mini-boreholes were drilled through ferricrete using a portable, handheld, gasoline powered, rock coring drill manufactured by Shaw Tool. Boreholes were drilled within 2 meters of the stream on the east and west banks to constrain local-scale groundwater variations on either side of the stream. Ferricrete samples were logged and collected during drilling. A subset of ferricrete samples were analyzed for bulk chemistry and a deionized water leach quantified the water-soluble fraction from the ferricrete samples. Groundwater levels and field parameters (temperature, pH, specific conductance, and dissolved oxygen) were measured and groundwater samples were collected using a peristaltic pump for major and trace element chemistry. Environmental tracer samples (stable water isotopes, dissolved noble gases, helium isotopes, and tritium) were collected using a submersible double-valve pump manufactured by Solinst Canada Ltd. Stream water samples were collected adjacent to mini-boreholes over a period of two days with no major precipitation events. References cited Bayer, R., Schlosser, P., Bonisch, G., Rupp, H., Zaucker, F., and Zimmek, G., 1989, Performance and blank components of a mass spectrometric system for routine measurement of helium isotopes and tritium by the 3He ingrowth method, in Sitzungsberichte der Heidelberger Akademie der Wissenschaften, Mathematisch-Naturwissenschaftliche Klasse, Springer, New York, vol. 5 pp. 241�279 available at https://doi.org/10.1007/978-3-642-48373-8. Hunt, A.G., 2015, Noble Gas Laboratory�s standard operating procedures for the measurement of dissolved gas in water samples: U.S. Geological Survey Techniques and Methods, book 5, chap. A11, 22 p., http://dx.doi.org/10.3133/tm5A11. U.S. Geological Survey Mineral Resources Program Analytical Chemistry, 2019, Analytical Contract Laboratory Method Summaries (AGAT) available online at https://www.usgs.gov/energy-and-minerals/mineral-resources-program/scie…. (Accessed October 4, 2019).