Hydrogeochemical and stream sediment reconnaissance basic data report for Winnemucca NTMS Quadrangle, Nevada

Abstract

This report presents the results of the geochemical reconnaissance sam pling in the Winnemucca 1x2 quadrangle of the National Topographic Map Series (NTMS). We collected wet and dry sediment samples throughout the 2 18,/70-km arid to semi-arid area and water samples at available streams, springs and wells. We present neutron activation analyses of uranium and trace elements and other measurements made in the field and laboratory in tabular hardcopy and microfiche format. The report includes 5 full-size overlays for use with the Winnemucca NTMS 1:250,000 quadrangle. Water sampling sites, water-sample uranium and thorium concentrations, sediment sampling sites, and sediment-sample total uranium and thorium concentrations are shown on the separate overlays. We present general geological and structural descriptions of the area, and describe the 12 known uranium occurrences. The results indicate that the uranium geochemistry of the area is diverse. High concentrations (greater than 5 ppm) of uranium in sediments are associated mainly with rhyolitic ash falls and flows and silicic intrusives. In defining areas of interest the ratio of relatively insoluble thorium to uranium was considered. The anomalies as defined are then the sediment samples containing low Th/U and high uranium concentrations. These areas consist mainly of fluvial-lacustrine units. Most known uranium occurrences were also identified by this technique. The main dumboldt River shows an irregular increase in uranium concentration downstream which may be related to agricultrual modification of the stream flow. U/Cl ratios were used to evaluate the effects of evaporative concentration. Of interest are spring and tributary waters containing high U/Cl and high uranium values. These waters mainly drain acid intrusives, silicic volcanic recks and related sediments. One such area is the Shoshone and Cortez Mountain:;. 1 deposits of mercury, lead, and zeolites. Althouqh there are numerous mining districts, there are only scattered occurrences of low-grade uranium. Twelve radioactive occurrences and p-.aerous recent uranium claims are shown on Fig. 3. This map is based on reports by Garside and Larson and 14 Beal. The uranium is found in a wide variety of environments, but most of it occurs within igneous rocks or related sediments. Host occurrences contain only uranium; two deposits contain uranium and other metals. Anomalous radioactivity is associated wi.r.h features in waterlaid tuff overlain by Tertiary rhyolite at Dacies Creek (T28N, R41E). At Lee Canyon (T30N, R52E), the Kei No. 2 claims contain uranium in siltstone, water-laid tuff, and Tertiary lake sediments. Similar occurrences exist at the Ela?k Hills claims and Deerhead claims in T32N, R52E. To the south, the Asphaltite prospect (T29N, K52E) contains uranium in strings and lenses of asphaltic pyrobituraen in northerly trending faults. The veins cut Paleozoic elastics and contain associated vanadium. Mid-Paleozoic carbonates contain autunite (?) near the foot of Cortez Canyon (T27N, R47E) in Crescent...

Interpretation of reconnaissance geochemical data from the Bureau of Land Management's Winnemucca District and Surprise Resource Area, northwest Nevada and northeast California

“…Nure sampling during the NURE program was done within the area of the WSRAA from 1978-1980 on a 1° x 2° quadrangle basis under the responsibility of two Department of Energy (DOE) national laboratories: Lawrence Livermore Laboratory (LLL), and Savannah River Laboratory (SRL). LLL was responsible for the Lovelock (Qualheim, 1979), and Winnemucca (Puchlik, 1978) quadrangles, and SRL was responsible for the McDermitt (Thayer and Cook, 1980), Reno (Bennett, 1980), and Vya (Cook, 1981) quadrangles. The actual sampling was done by contract personnel.…”