Dataset includes rock and soil gas carbon and strontium values. Rock samples were collected from outcrop locations as well as from drill cuttings. Rock type associations were made based on the DeWitt and others (2008) geology map.
Soil gas samples were collected from 4 inch augered soil core holes completed to different depths at three separate sampling locations. Material at the bottom of the soil core hole was collected and analyzed in addition to soil gas for some samples. The augered soil cores were backfilled with two trowel scoops of material removed from soil core then two scoops of clean silica sand were added to the soil core hole. A stainless steel tube was then added to the hole and 10 more scoops of clean silica sand were added to cover the sampler followed by infilling and compaction with the remainder of the material removed from the soil core. The stainless steel tubes consisted of 1/8 inch diameter stainless steel tube with three small slits in the lower 2 to 3 inches of the tube that were covered by stainless steel screen mesh attached with epoxy and electrical tape. The top of the tube was sealed with a stainless steel Swagelok compression fitted plug and covered with a 5 inch long 2 inch diameter capped PVC pipe. Soil core holes were dug in August 2017 and soil gas samples were collected November 2017. The soil gas sample was extracted from the sampling tube with a disposable syringe and needle after initial head space in the connector was removed. Samples were injected into 10 mL microcentrifuge tubes with septum screw caps that had been pre-filled with He gas two days prior to sampling. Three tubes were filled with various quantities of soil gas 5, 10, and 15mL. A replicate sample was collected from each depth at the Big Chino Water Ranch and 0.5 meter depth at the Camp Wood Area sites.
The soil gas samples were analyzed for the carbon isotopicratio (delta 13C) at the University of Arizona Geoscience Environmental Isotope Laboratory. Soil and rock samples were powdered then analyzed by the USGS Mineral Resources Program contract laboratory for carbon dioxide, carbonate carbon, and organic carbon. Powdered rock samples were analyzed for strontium-87/strontium-86 by the USGS National Research Program Laboratory in Menlo Park, Calif. using methods described in Bullen and others (1996).
References:
Bullen, T.D., Krabbenhoft, D., and Kendall, C., 1996, Kinetic and mineralogic controls on the evolution of groundwater chemistry and 87Sr/86Sr in a sandy silicate aquifer, northern Wisconsin: Geochimica et Cosmochimica Acta, v. 60, no. 10, p. 1807–1821.
DeWitt, E., Langenheim, V., Force, E., Vance, R.K., Lindberg, P.A., and Driscoll, R.L., 2008, Geologic map of the Prescott National Forest and the headwaters of the Verde River, Yavapai and Coconino Counties, Arizona. US Geological Survey Scientific Investigations Map 2996 scale 1: 100,000, 100-p, pamphlet.
