Hydrogeochemical Investigations in the

Osgood Mountains, North-Central Nevada

Bulletin 2210-B

U.S. Department of the Interior

U.S. Geological Survey
Hydrogeochemical Investigations in the 

Osgood Mountains, North-Central Nevada

By Richard B. Wanty, Byron R. Berger, Michele L. Tuttle, 

Paul H. Briggs, Allen L. Meier, and James G. Crock

U.S. Geological Survey Bulletin 2210-B

U.S. Department of the Interior

U.S. Geological Survey

Chapter B of

Geoenvironmental Investigations of the Humboldt River Basin, Northern Nevada

Edited by Lisa L. Stillings
U.S. Department of the Interior

Dirk Kempthorne, Secretary

U.S. Geological Survey

P. Patrick Leahy, Acting Director

Any use of trade, product, or firm names in this publication

is for descriptive purposes only and does not

imply endorsement by the U.S. Government

This publication is only available online at:

http://pubs.usgs.gov/bul/2210/b/

Posted online June 2006, version 1.0
Preface 

Northern Nevada is one of the world’s foremost regions of gold production. The 

Humboldt River Basin (HRB) covers 43,500 km2 in northern Nevada (Crompton, 1995), 

and it is home to approximately 18 active gold and silver mines (Driesner and Coyner, 

2001) among at least 55 significant metallic mineral deposits (Long and others, 1998). 

Many of the gold mines are along the Carlin trend in the east-central portion of the HRB, 

and together they have produced 50 million ounces of gold from 1962 (when the Carlin 

mine first opened) through April 2002 (Nevada Mining Association, 2002). Mining is 

not new to the region, however. Beginning in 1849, mining has taken place in numerous 

districts that cover 39 percent of the land area in the HRB (Tingley, 1998). In addition to 

gold and silver, As, Ba, Cu, Fe, Hg, Li, Mn, Mo, Pb, S, Sb, V, W, Zn, and industrial commodities such as barite, limestone, fluorite, sand and gravel, gypsum, gemstones, pumice, 

zeolites, and building stone, have been extracted from the HRB (McFaul and others, 

2000).

Due to the large amount of historical and recent mining in the HRB, the Bureau of 

Land Management (BLM) in Nevada asked the U.S. Geological Survey (USGS) Mineral 

Resources Program to conduct a series of mineral-deposit-related environmental studies in the HRB. BLM required data and geoenvironmental interpretations regarding (1) 

the chemical composition of water, soil, sediment, and mine waste in the HRB, (2) the 

natural background chemistry of these materials, and (3) how mining activities may have 

altered their chemistry. The paper that follows describes one of the studies conducted by 

the USGS Minerals Program to answer these and similar questions. 

All papers within this series of investigations can be found as lettered chapters of 

USGS Bulletin 2210, Geoenvironmental Investigations of the Humboldt River Basin, 

Northern Nevada. Each chapter is available separately online.

References Cited

Crompton, E.J., 1995, Potential hydrologic effects of mining in the Humboldt River Basin, northern 

Nevada: U.S. Geological Survey Water Resources Investigations Report 94-4233, 2 sheets.

Driesner, D., and Coyner, A., 2001, Major mines of Nevada 2000: Mineral industries in Nevada’s 

economy: Nevada Bureau of Mines and Geology Special Publication P-12, 28 p.

Long, K.R., DeYoung, J.H., Jr., and Ludington, S.D., 1998, Significant deposits of gold, silver, copper, 

lead, and zinc in the United States: U.S. Geological Survey Open-File Report 98-206A, 33 p. [USGS 

Open-File Report 98-206B contains one 3.5-inch diskette].

McFaul, E.J., Mason G.T., Jr., Ferguson, W.B., and Lipin, B.R., 2000, U.S. Geological Survey mineral 

databases—MRDS and MAS/MILS: U.S. Geological Survey Digital Data Series DDS-52, two CDROMs.

Nevada Mining Association, 2002, Industry to celebrate 50 millionth ounce of gold: Nevada Mining 

Association News Release, April 11, 2002.

Tingley, J.V., 1998, Mining districts of Nevada (2nd ed.): Nevada Bureau of Mines and Geology 

Report 47d, one CD-ROM.


Contents

Preface ..........................................................................................................................................................III

Abstract...........................................................................................................................................................1

Introduction.....................................................................................................................................................1

Purpose and Scope ..............................................................................................................................1

Physical Geography..............................................................................................................................1

Geology...................................................................................................................................................2

Methods...........................................................................................................................................................3

Field Methods........................................................................................................................................3

Laboratory Methods.............................................................................................................................4

Results and Discussion.................................................................................................................................4

Temporal Variability..............................................................................................................................4

Spatial Variability ................................................................................................................................17

Variations at Tens of Kilometers..............................................................................................17

Variations at Hundreds to Thousands of Meters..................................................................17

Variations at Meters to Tens of Meters .................................................................................18

Conclusions...................................................................................................................................................19

References Cited..........................................................................................................................................19

Figures

1. Photograph showing the upper reaches of Granite Creek in the 

southeastern Osgood Mountains................................................................................................2

2. Geologic map of the Osgood Mountains intrusive rocks........................................................3

3. Index map of the Osgood Mountains study area ...................................................................18

4. Variation in sulfate-sulfur δ34S as a function of latitude.......................................................18

Tables

1A. Sample-site descriptions and locations, and results of field analyses 

for samples collected in 1999 ......................................................................................................5

1B. Sample-site descriptions and locations, and results of field analyses 

for samples collected in 2000 ......................................................................................................6

2. Results of anion analyses of water samples.............................................................................7

3A. ICP-AES results for water samples collected in 1999 .............................................................8

3B. ICP-AES results for water samples collected in 2000 .............................................................9

3C. ICP-MS results for water samples collected in 1999.............................................................10
VI

3D. ICP-MS results for water samples collected in 2000.............................................................12

4. Results of sulfur isotopic analyses of water samples...........................................................14

5. Comparison of 1999 and 2000 samples from the same locations ........................................14
Abstract

Field investigations performed in the Osgood Mountains 

during the summers of 1999 and 2000 were designed to test 

methods of combining geologic, hydrologic, and geochemical investigations. The goals were to develop a more thorough 

understanding of the movement of water through the study 

area and to understand the water-rock reactions that may occur 

along flow paths. The Osgood Mountains were chosen for 

study because they represent a well-defined geologic system, 

based on existing and new field data. New work in the area 

focused on gathering more data about fractures, faults, and 

joints and on collecting water samples to evaluate the role of 

geologic structures on hydrologic and geochemical properties 

of the ground-water/surface-water system. Chemical methods 

employed in the study included measuring traditional field 

parameters (e.g., pH, temperature, conductivity, dissolved 

oxygen) as well as Fe2+ and collecting a variety of samples 

that were preserved for later laboratory analysis. Hydrologic 

methods included closely spaced evaluations of substream 

hydraulic head to define ground-water discharge and recharge 

zones as well as some measurements of stream discharge. 

Geologic investigations focused on the locations and orientations of fractures and kinematic indicators of slip observable 

in outcrops.

Introduction

Purpose and Scope

This study was designed to test the hypothesis that a 

well-developed conceptual model of the geologic and structural characteristics of an area can be used to help evaluate 

the hydrology and hydrochemistry of that area. The geologic 

model for the Osgood Mountains, described in detail below, 

accounts for the orientations of fractures observed in the 

granodiorite bedrock. The combined network of northwest-, 

northeast-, and east-trending fractures should comprise a 

regional flow network, with local flow (at the scale of meters 

to perhaps hundreds of meters) conducted by single fractures or sets of fractures. Water samples were collected in an 

attempt to evaluate the roles that individual fractures or fracture sets may play in the local and regional hydrologic regime. 

Although most of our samples were collected from streams, 

a number of springs were sampled as well as one artesian 

well. During our sampling trips, we walked along the major 

streams in the area, monitoring field parameters such as conductivity and pH, and collecting samples when changes were 

observed; we also measured the hydraulic head of hyporheic 

water (Wanty and Winter, 2000) to evaluate the hydraulic relationships between surface water and ground water. Using the 

hydrologic and chemical results, we can evaluate flow systems 

at a variety of spatial scales.

Physical Geography

The Osgood Mountains in north-central Nevada include 

two large granodioritic intrusive-rock bodies, which form the 

eastern half of the range (Hotz and Willden, 1964). Elevations 

in the valley bottom are approximately 1,500 m above sea 

level, and the elevation of Adam Peak, the highest point in the 

range, is 2,625 m. Slopes are generally steep and rocky, with 

only thin soil development (fig. 1).

The average annual rainfall in Winnemucca, Nev., 

approximately 40 km southwest of the Osgoods, is 20 cm; 

that for Golconda, approximately 30 km south, is 18 cm. 

Both of these weather stations are located in valleys, well 

below the elevation of the Osgood Mountains where a 

slightly higher precipitation is expected. Potential evaporation 

in the area varies from < 600 mm to 1,800 mm per year 

(Shevenell, 1996). As a result, the vegetative cover is limited 

to sparse cover with grasses and short shrubs, with trees and 

taller shrubs confined to riparian zones (Bailey, 1995, 1998).

Hydrogeochemical Investigations in the 

Osgood Mountains, North-Central Nevada

By Richard B. Wanty,1 Byron R. Berger,1 Michele L. Tuttle,1 Paul H. Briggs,1

Allen L. Meier,1 and James G. Crock1

1

 U.S. Geological Survey, Box 25046, Mail Stop 973, Denver Federal Center, 

Denver, CO 80225, U.S.A.


Geology

The Osgood Mountains intrusive rocks were emplaced 

about 95 m.y. ago (B.R. Berger and L. Snee, oral commun., 

2002) under regional tectonic stresses dominated by compression, the maximum principal stress axis (σ1) of which was 

parallel to Earth’s surface and oriented slightly east of north. 

Under these tectonic conditions, long strike-slip faults (kilometers to tens of kilometers) developed, with an azimuth of 

approximately 330°.There are three such faults in the field 

area, shown on figure 2. These faults are the major bounding 

structures for the Osgood Mountains stock. The Getchell fault, 

one of the bounding structures, forms the northeast edge of 

the northern intrusive body and controls gold mineralization 

in the Getchell mine in Paleozoic sedimentary rocks near their 

contact with granodiorite. The Osgood Creek fault is shown 

as a dashed line (fig. 2) between the two intrusive rock bodies. 

The southernmost bounding fault is not observed in outcrop 

but is inferred by a pervasive alteration zone parallel to Granite Creek, observed by Neuerberg (1966) as a zone of sulfide 

mineral enrichment in the stock.

As displacement occurred along the strike-slip faults, 

they interacted mechanically where they overlap. As a consequence, displacement on the strike-slip faults was partially 

accommodated through extension between them, thereby 

resulting in the development of two extensional stepovers, or 

pull-apart structures, between them. The extensional sidewall 

faults of the pull-aparts strike N. 45° E. (±15°). The two lobes 

of the Osgood Mountains stock were emplaced into the two 

pull-apart structures and accommodated extensional strain 

between the master strike-slip faults. In this structural model, 

regional compression formed a container for present-day 

regional fluid flow, the details of which are related to the compartmentalization of permeability imposed on the area during 

strike-slip transtensional tectonics. 

Due to the oblique angle of convergence of the North 

American and Pacific tectonic plates during the Late Cretaceous, northwest-striking strike-slip faults in what is now the 

Great Basin had a right-lateral sense of displacement. Ideally, 

north- to north-northeast-striking faults would accommodate 

extension and northeast-striking faults would accommodate 

antithetic shear. Slip indicators observed within the Osgood 

Mountains stock are consistent with this model. However, the 

north-northeast to northeast strikes of normal faults along the 

margins of the two lobes of the stock imply that extensional 

strain was accommodated heterogeneously, and the differing shapes of the lobes reflect different responses to local 

mechanical conditions. We suggest that this heterogeneity in 

strain accommodation is in part a reflection of some left-lateral 

slip being accommodated on east-west-striking fractures that, 

in turn, led to northeast-striking extension. Kinematic indicators of slip within the stock were recorded in the field and are 

shown in figure 2. The transverse set of fractures and dikes 

is oriented N. 90° E. (±15°). Thus, the fracture network consists of two predominant sets of shear fractures and a range of 

Figure 1. Photograph showing the upper reaches of Granite Creek in the southeastern Osgood 

Mountains. Steep rocky slopes and dry climate result in thin soil development and sparse vegetative 

cover.

 Geoenvironmental Investigations of the Humboldt River Basin, Northern Nevada
extensional fractures that resulted from the far- and near-field 

stresses acting on intrusive rocks at the time of emplacement 

and one set of antecedent, basement shear fractures that were 

reactivated during the Late Cretaceous. Each of these fracture 

sets now provides pathways for present-day ground-water flow 

and for interactions between ground and surface water.

Methods

Field Methods

Water samples were collected in the field in June and 

September of 1999 and in June of 2000. In the latter two sampling trips, sites that were sampled in the first trip were resampled to evaluate the degree of change of the overall system and 

to give some idea of whether the results from each trip could 

be directly compared. In 1999, 21 samples were collected 

from streams and springs; in 2000, 24 samples were collected. 

Of the sites sampled in 2000, five were repeat visits to previous sampling sites.

Field sampling methods included geochemical and 

hydrologic techniques. At each sampling site, measurements 

were made for temperature, specific conductivity, and pH of 

the water using methods cited in Wood (1976). The pH of each 

sample was measured using a portable pH meter with automatic temperature compensation. The pH meter was calibrated 

each morning using three standard buffers, with nominal pH 

values of 7.00, 4.01, and 10.00 at 25°C. Calibration slopes 

were always within 5 percent of ideal Nernstian behavior. At 

each subsequent stop during the day, the pH calibration was 

checked by measuring the pH of one of the standard buffers. 

Resulting values were always within ±0.05 pH units of the 

accepted value. The accuracy of each sample pH measurement 

is probably also within this range. Temperature was measured 

using a NIST-traceable electronic thermistor, accurate to 

within ±0.1°C. The stainless steel housing of the temperature sensor allowed temperature measurements to be made in 

the stream itself, as well as in the streambed by inserting the 

sensor into the bed. In most cases, temperature differences of 

several degrees Celsius were observed. Specific conductivity 

(SpC) was measured using a portable temperature-compensated probe, sensitive to within ±10 microsiemens per centimeter (μS/cm) and accurate to within ±20 μS/cm.

Field analyses also were conducted for Fe2+ and dissolved oxygen (DO) using colorimetric methods developed by 

Chemetrics, Inc. In both cases, measurements were made by 

breaking the tip off an evacuated ampoule that had reagents 

sealed inside. When the tip was broken, sample was rapidly 

drawn into the ampoule, mixing with the reagents. Analytical 

determinations were made by comparison to standards sealed 

in similar ampoules or by comparison to a printed color chart. 

Between 0.1 and 1 mg/L, ferrous iron was determined with an 

accuracy of ±0.1 mg/L. Between 1 and 10 mg/L, the accuracy 

was ±1 mg/L. Dissolved oxygen was determined to a minimum level of 1 mg/L, with an accuracy of ±1 mg/L.

Samples were collected in the field for later laboratory 

analyses for major and trace cations, anions, alkalinity, and 

mercury. Anion samples were filtered through 0.45-μmnominal-pore-diameter cellulose acetate filters and refrigerated with no further treatment. Cation samples were filtered 

through the same 0.45-μm filter and acidified by adding 0.5 

mL of concentrated ultra high purity nitric acid to each 30-mL 

17'30" 117 ̊15'

41 ̊7'30"

10'

12'30"

Adam

Peak

f

f

d

d

d

f

f

f

f

f

f

d d

f

f

f

f

Figure 2. Geologic map of the Osgood Mountains intrusive rocks. 

Base map from Hotz and Willden (1964). Short lines represent measured orientations of fractures, joints, and dikes (marked with the 

letter “d”). Faults are marked with the letter “f.” Where observed 

in the field, kinematic indicators are shown as arrows denoting the 

sense of observed strike-slip offset of fractures.

Hydrogeochemical Investigations in the Osgood Mountains, North-Central Nevada 
sample. Samples for alkalinity analyses were collected by 

filling a 125-mL bottle, without filtering or acidification and 

refrigerating. Mercury samples were filtered with the same 

0.45-μm filter into a 60-mL glass bottle. The bottles for mercury analyses were acid washed prior to sampling, and mercury was preserved with a solution of nitric acid and sodium 

dichromate (O’Leary and others, 1996). For sulfur isotopes, 

samples were collected into 1-L high-density polyethylene 

bottles and refrigerated. The samples were filtered through 

0.45-μm filters within 2 weeks of sample collection. For every 

sample type except alkalinity, field blanks were collected using 

deionized water that was brought from the laboratory and 

treated as a sample in the field. This procedure helped assure 

the purity of reagents used for sample preservation, as well 

as assuring that the samples were not contaminated. In every 

case, analyses of the field blanks showed below detection concentrations for all constituents.

Laboratory Methods

Upon completion of field work, samples were transported 

back to USGS laboratories in Denver, Colo. Anion and alkalinity samples were kept cool during transport in insulated 

containers. Cation analyses were performed by inductively 

coupled plasma, atomic emission spectroscopy (ICP-AES) 

(Briggs, 1996) and by ICP-mass spectrometry (ICP-MS) 

(Lamothe and others, 1996). The ICP-AES results are preferred for major cations (Mg, Ca, Na, K) and Fe, Al, and Si. 

The ICP-MS results are preferred for all other constituents, 

including first- and second-row transition elements, rare earth 

elements, some actinides, etc. All results are reported in the 

data tables accompanying this report.

Anion analyses were conducted on a Dionex DX-500 

ion chromatography (IC) system. The chromatography columns used were the AG-14 and AS-14 guard and separator 

columns, with a CO3/HCO3 eluent. Using this method, good 

analytical separations were made for fluoride, chloride, nitrate, 

phosphate, and sulfate. The IC was calibrated each day with a 

minimum of six standards. The accuracy and precision of the 

IC was checked by running standards as unknowns in at least 

10 percent of the IC runs and by running duplicate analyses of 

5 to 10 percent of all samples.

Alkalinity was determined by titrating a 50-mL aliquot 

of sample with standardized sulfuric acid (Papp and others, 

1996). An Orion model 960 automatic titrator was used for 

these analyses. This instrument includes a 15-sample carousel 

in which to load samples and standards. For each set of 15 

analyses, at least two standards were run to check for accuracy 

and precision.

Samples collected for mercury analyses were filtered in 

the field through 0.45-μm filters and stored in glass bottles 

that had been previously washed with nitric acid and dried. 

The samples were preserved with a mixture of nitric acid and 

sodium dichromate (O’Leary and others, 1996). Total mercury in these waters was determined using a cold vapor flow 

injection–atomic fluorescence spectrometry method modified 

from the method as given in O’Leary and others (1996).

Sulfate was precipitated as BaSO4 from 0.45-μm-filtered 

samples for isotope analysis. Approximately 0.7 mg of BaSO4

was combusted with V2O5 in an elemental analyzer. The SO2

gas released was analyzed by mass spectrometry with a reproducibility of ±0.2 ‰. Isotope values are reported relative to the 

Cañon Diablo Troilite standard.

Results and Discussion

Results of field analyses are shown in table 1, including 

locations as determined by global positioning system (GPS). 

Laboratory results are shown in tables 2 (anions by IC) and 3 

(cations by ICP-AES and ICP-MS). Results of isotopic analyses are shown in table 4

The sampling strategy employed in this study is amenable 

to evaluating spatial as well as some temporal variations of 

the Osgood Mountains hydrogeologic system. Evaluation of 

temporal variations is mostly limited to direct comparison 

of results of repeated sampling at selected individual sites, 

whereas the evaluation of spatial variations can be made at 

scales ranging from several kilometers to several meters.

Temporal Variability

Table 5 shows the direct comparisons of data for consecutive years for the same sample site. Five sites that were 

sampled in 1999 were resampled in 2000. Table 5 is displayed 

in three parts: the first shows selected field parameters and 

anion data; the second shows selected ICP-MS analytical 

results; and the third part shows ICP-MS results normalized 

to chloride. This latter operation was performed to evaluate 

whether variations between the 2 years worth of sampling can 

be attributed to evaporation, or if some other process(es) must 

have occurred. For each parameter from each pair of samples, 

the difference from 1999 to 2000 is calculated as the difference between the two numbers divided by their mean. For 

the most part, the differences are less than 25 percent, which 

is a reasonable threshold above which the differences are 

unlikely to be due simply to analytical error. As seen in table 

5, the parameters whose differences exceed 25 percent are not 

systematic throughout the range of results for a sample pair, 

nor do they differ in the same direction (i.e., some parameters 

increased while others decreased from 1999 to 2000).

When normalizing to chloride, the observations are substantially the same—the differences are not systematic and not 

in the same direction. Another observation is that, with only 

a few exceptions, the major cations (Ca, Mg, Na, and K) and 

anions (F, Cl, and SO4) are within 25-percent variation. There 

Text continues on page 17

 Geoenvironmental Investigations of the Humboldt River Basin, Northern Nevada
Table 1A. Sample-site descriptions and locations, and results of field analyses for samples collected in 1999. 

[Latitude (Lat) and longitude (Long) given in decimal degrees (North American Datum of 1927). SpC (specific conductivity) given in microsiemens per cm corrected to 25°C. 

Water Streambed Dissolved 

Sample no. Description Sample Lat Long pH SpC temp temp oxygen 

date (°C) (°C) (mg/L) 

99NV-20

Spring at top of drainage north of Rocky 

Cr. 22-Jun-99 41.2107 -117.2675 7.06 410 11.9 3 

99NV-21 Spring at top of Hansen Canyon 22-Jun-99 41.1989 -117.2808 7.41 220 15 12.3 3 99NV-22 Small stream draining wetland area 22-Jun-99 41.1979 -117.2802 7.36 280 23 3.5 99NV-23

Low-conductivity spring about 20 m S. of 

site 22 22-Jun-99 41.1977 -117.2798 6.46 120 9.5 9.5 3.5 

99NV-24 Hansen Creek 22-Jun-99 41.1972 -117.2778 8.03 210 18.4 16.2 4 99NV-25 Summer Camp Creek 22-Jun-99 41.1865 -117.2670 8.14 240 14.4 14 7.5 99NV-26 Rocky Creek 22-Jun-99 41.2070 -117.2692 8.12 310 14.6 15.2 6.5 99NV-27 Alpine mine spring 23-Jun-99 41.1957 -117.2875 7.56 220 8 7.1 6.5 99NV-28 Anderson Canyon near Richmond mine 23-Jun-99 41.2067 -117.2884 8.23 270 9.7 9.1 6.5 99NV-29 Julian Creek west of Osgood stock 23-Jun-99 41.1870 -117.2844 7.07 140 11 10.3 6.5 99NV-30

Julian Creek about 500-800 m inside 

Osgood stock 23-Jun-99 41.1838 -117.2783 7.95 150 15.2 16 3.5 

99NV-31 Julian Creek above unnamed tributary 23-Jun-99 41.1775 -117.2711 8.10 180 19.3 19.5 5 99NV-32 Julian Creek below sites 31 and 33 23-Jun-99 41.1763 -117.2674 8.08 250 17.5 4.5 99NV-33 Unnamed tributary to Julian Creek 23-Jun-99 41.1771 -117.2712 8.02 300 13.3 13.8 6 99NV-34 Unnamed tributary to Granite Creek 24-Jun-99 41.1486 -117.2943 8.46 180 17.4 15.3 4.5 99NV-35 Tributary to Granite Creek 24-Jun-99 41.1520 -117.2883 8.20 170 19.2 16.7 5.5 99NV-36 Small tributary to Granite Creek 24-Jun-99 41.1522 -117.2921 7.95 120 15.9 12.8 6.5 99NV-37 Granite Creek 24-Jun-99 41.1517 -117.2939 8.09 210 13.2 12 5.5 99NV-38 Granite Creek 24-Jun-99 41.1365 -117.2705 8.26 240 17.5 15.1 5 99NV-39 Bunch Canyon 24-Jun-99 41.1508 -117.2612 8.12 210 14.7 6.5 99NV-40 Osgood Creek 24-Jun-99 41.1632 -117.2603 8.31 230 18.9 4.5 
Table 1B. Sample-site descriptions and locations, and results of field analyses for samples collected in 2000. 

[Latitude (Lat) and longitude (Long) given in decimal degrees (North American Datum of 1927). SpC (specific conductivity) given in microsiemens per cm corrected to 25°C. n

Water Streambed Dissolved 

Sample no. Description Sample Lat Long pH SpC temp temp oxygen 

date (°C) (°C) (mg/L) 

00NV-1

Spring north of Rocky Canyon, on Burma 

Rd. 01-Jun-00 41.2071 -117.2743 6.76 130 9.0 8.7 4 

00NV-2 Spring at head of Rocky Canyon 01-Jun-00 41.2052 -117.2737 6.75 160 9.2 n.d. 4 00NV-3 Rocky Creek just below road 01-Jun-00 41.2072 -117.2689 8.30 300 16. n.d. 5 00NV-4 Spring at crest of ridge along Rocky Creek 01-Jun-00 41.2055 -117.2641 6.63 220 10.5 n.d. 8 00NV-5 Spring above N. Rocky Cr. 02-Jun-00 41.2103 -117.2675 7.44 370 15.1 11.8 5 00NV-6 Spring 5-10 m N. of 00NV-5 02-Jun-00 41.2103 -117.2675 7.75 480 18.1 11.2 00NV-7 Rocky Creek at jog 02-Jun-00 41.2060 -117.2641 8.17 290 21.4 11.1 6 00NV-8 Hansen Creek below possible lineament 02-Jun-00 41.1964 -117.2657 8.25 320 15.3 13.9 6 00NV-9 Hansen Creek above dike ridge 02-Jun-00 41.1972 -117.2658 7.75 370 21.6 18.8 6 

00NV-10

Osgood Creek above Valley View mine 

road. 03-Jun-00 41.1637 -117.2605 8.23 220 11.5 10.6 10 

00NV-11 Tributary to Osgood Creek from south 03-Jun-00 41.1641 -117.2738 7.62 180 12.3 10.5 7 00NV-12 Osgood Creek above 2nd road crossing 03-Jun-00 41.1655 -117.2762 8.22 170 12.9 10.7 8.5 00NV-13 N. Fork Osgood Creek 03-Jun-00 41.1662 -117.2798 7.87 270 12.8 11.7 8 00NV-14 S. Fork Osgood Creek 03-Jun-00 41.1659 -117.2799 7.74 160 12.7 11.2 8 00NV-15 S. Fork Osgood Creek 03-Jun-00 41.1652 -117.2866 7.91 130 14.3 13.3 9 00NV-16 Small tributary to S. fork of Osgood Cr. 03-Jun-00 41.1633 -117.2843 7.57 140 16.1 13.1 8 00NV-17 Small drainage to south of Osgood Cr. 04-Jun-00 41.1594 -117.2715 6.79 120 10.9 n.d. 7 00NV-18 Approx. 200-300 m downstream from site 17 04-Jun-00 41.1594 -117.2695 7.61 140 20.6 n.d. 7 0

00NV-19 Same creek, lower elevation from site 18 04-Jun-00 41.1596 -117.2644 7.76 170 19.7 n.d. 8 00NV-20 Summer Camp Creek at lower road crossing 05-Jun-00 41.1853 -117.2534 8.28 280 12.3 12.0 8 00NV-21 Small stream along N of Summer Camp Cr. 05-Jun-00 41.1891 -117.2567 7.41 280 13.3 12.1 8 00NV-22

Approx 500 m upstream from site 20 on 

Summer Camp Creek 05-Jun-00 41.1872 -117.2577 8.43 270 13.3 12.2 7 

00NV-23 Summer Camp Creek at upper road 05-Jun-00 41.1868 -117.2668 8.28 270 17.1 12.6 7 00NV-25 Anderson Canyon south of Richmond mine 05-Jun-00 41.2066 -117.2886 8.34 270 11.3 10.4 7 
Table 2. Results of anion analyses of water samples. 

[All results reported in mg/L. n.d., not detected. Samples 99NV-41 and 00NV-24 are field blanks] 

Sample no. F Cl NO3 PO4 SO4

Samples collected in 1999 

99NV-20 0.33 13.5 4.2 0.45 40.5

99NV-21 0.21 4.97 0.36 0.58 7.44

99NV-22 0.23 5.53 0.23 0.62 9.03

99NV-23 0.16 3.78 0.2 n.d. 8.72

99NV-24 0.21 4.61 n.d. 0.62 7.59

99NV-25 0.2 4.46 1.39 0.28 12.3

99NV-26 0.29 7.69 0.73 0.52 18.1

99NV-27 0.09 1.16 3.37 n.d. 4.75

99NV-28 0.17 5.37 0.39 0.23 13.3

99NV-29 0.07 2.56 1.43 n.d. 9.33

99NV-30 0.08 2.88 1.52 n.d. 10.7

99NV-31 0.11 3.71 1.92 0.2 12.6

99NV-32 0.16 4.09 1.6 0.17 14.6

99NV-33 0.2 4.47 0.7 n.d. 20.0

99NV-34 0.11 0.99 0.29 n.d. 11.4

99NV-35 0.18 2.08 4.38 n.d. 10.5

99NV-36 0.15 2.35 12.78 n.d. 7.95

99NV-37 0.16 1.24 1.69 n.d. 17.6

99NV-38 0.21 3.74 2.45 n.d. 17.4

99NV-39 0.23 5.85 n.d. 0.52 10.6

99NV-40 0.18 3.15 1.17 0.36 18.4

99NV-41 0 0 0.2 0 0

Samples collected in 2000 

00NV-1 0.22 8.1 4.1 n.d. 18

00NV-2 0.21 2.84 1.1 n.d. 8.84

00NV-3 0.31 8.5 0.06 0.36 19

00NV-4 0.24 5.79 5.1 n.d. 14

00NV-5 0.37 12.5 n.d. 0.26 36.8

00NV-6 0.3 13.1 n.d. 0.26 38

00NV-7 0.37 7.54 n.d. 2 18

00NV-8 0.29 9.4 n.d. n.d. 24.9

00NV-9 0.24 10.2 n.d. n.d. 24.8

00NV-10 0.16 2.98 0.1 0.36 18.2

00NV-11 0.19 4.84 n.d. n.d. 26.7

00NV-12 0.15 1.91 0.18 n.d. 12.84

00NV-13 0.17 1.47 n.d. n.d. 15.54

00NV-14 0.13 1.79 0.34 n.d. 10.37

00NV-15 0.1 1.09 n.d. n.d. 8.77

00NV-16 0.15 2.32 n.d. 1.92 10.9

00NV-17 0.13 2.64 n.d. n.d. 11.71

00NV-18 0.17 2.85 n.d. n.d. 7.86

00NV-19 0.17 2.42 n.d. n.d. 6.32

00NV-20 0.29 6.61 0.11 n.d. 17

00NV-21 0.34 7.08 13.3 n.d. 23

00NV-22 0.28 5.42 n.d. 1.97 14.1

00NV-22a 0.29 5.38 n.d. 1.95 14

00NV-23 0.24 5.3 0.06 0.46 14.2

00NV-24 0 0 0 0 0

00NV-25 0.19 5.5 0.1 0.36 12

Hydrogeochemical Investigations in the Osgood Mountains, North-Central Nevada 
Table 3A. ICP-AES results for water samples collected in 1999. 

[Analyses not shown include Be, V, Co, Cr, Ag, Ni, and Zn (all < 10 μg/L), Ti (all < 50 μg/L), As and Sb (all < 100 μg/L), Mo (all < 20 μg/L, except 99NV-39, which was 25 μ(all < 50 μg/L)] 

Field Sample Ca Mg Na K Li B Al Si Mn Fe 

no. description (mg/L) (mg/L) (mg/L) (mg/L) (μg/L) (μg/L) (mg/L) (mg/L) (μg/L) (mg/L) 

99NV20 Spring north of Rocky Cr. 51 9.9 36 4.3 18. 140 0.22 19.1 <10 <0.02 99NV21 Spring at top of Hansen Canyon 31 5.7 16 4.1 <10 71. 0.020 21.3 22 0.048 99NV22 Small stream in Hansen canyon 29 5.4 17 4.8 37. 140 0.014 23.4 22. 0.12 99NV23 Small stream in Hansen canyon 17 3.1 13 3.2 <10 34 0.27 22.8 150 0.17 99NV24 Hansen Creek 27 4.9 16 4.3 <10 65 0.012 22.4 25 0.025 99NV25 Summer Camp Cr. 39 4.6 14 4.3 <10 55 0.11 19.8 <10 0.13 99NV26 Rocky Cr. 38 7.5 24 4.2 13 110 <0.01 20 27 <0.02 99NV27 Alpine mine pit water 51 1.6 3.2 0.64 <10 15 <0.01 13 <10 <0.02 99NV28 Andersen Canyon near Richmond mine 45 4.0 11. 2.3 <10 45 <0.01 19.6 <10 <0.02 99NV29 Julian Cr. near top of drainage 19 3.8 8.0 2.5 <10 24 <0.01 12.5 <10 <0.02 99NV30 Julian Cr. 21 4.2 8.9 2.8 <10 26 <0.01 13.1 <10 <0.02 99NV31 Julian Cr. 23 4.9 12 3.8 <10 39 <0.01 14.5 <10 <0.02 99NV32 Julian Cr. 34 4.9 12 3.2 <10 46 <0.01 15.9 <10 <0.02 99NV33 Tributary to Julian Cr. 52 3.5 11 2.1 <10 45 <0.01 17.3 <10 <0.02 99NV34 Tributary to Granite Cr. 30 4.8 5.8 0.79 <10 19 <0.01 10.7 <10 <0.02 99NV35 Tributary to Granite Cr. 19 3.6 12 2.8 <10 48 <0.01 14.1 <10 <0.02 99NV36 Tributary to Granite Cr. 14 3.3 9.6 2.1 <10 29 <0.01 12.5 <10 <0.02 99NV37 Granite Cr. 36 2.2 5.5 1.5 <10 21 <0.01 14.8 <10 <0.02 99NV38 Granite Cr. 33 4.6 12 2.8 <10 52 <0.01 14.6 <10 <0.02 99NV39 Bunch Canyon 22 5.2 18 4 <10 77 <0.01 16.5 <10 <0.02 99NV40 Osgood Cr. 35 3.2 8.9 2.4 <10 38 <0.01 15.2 <10 <0.02 99NV41 Field blank <0.1 <0.1 <0.1 <0.1 <10 <10 <0.01 <0.1 <10 <0.02 
Table 3B. ICP-AES results for water samples collected in 2000. 

[Analyses not shown include Be, V, Cr, Co, Ni, Cu, Zn, Ag, and Cd (all < 10 μg/L), Al (all < 10 μg/L, except 00NV-16, which was 18 μg/L), Ti (all < 50 μg/L), Fe (all < 50 μg/19, which were both 13 μg/L), As and Sb (all < 100 μg/L), Mo (all < 20 μg/L), and Pb (all < 100 μg/L] 

Field Sample Ca Mg Na K Li B Si 

no. description (mg/L) (mg/L) (mg/L) (mg/L) (μg/L) (μg/L) (mg/L) 

00NV-1 Spring north of Rocky Canyon 28 4.9 22 3.4 13 76 16 00NV-2 Spring at head of Rocky Canyon 22 3.9 14 2.1 <10 50 14 00NV-3 Rocky Creek just below road 36 6.8 26 3.9 14 120 19 00NV-4 Spring at ridge crest above Rocky Cr. 21 3.9 20 2.3 16 69 16 00NV-5 Spring above N Rocky Cr. 47 9.1 36 4.1 20 150 19 00NV-6 Spring 5-10 m N. of 00NV-5 50 9.6 38 4.3 21 160 18 00NV-7 Rocky Creek at jog 35 6.1 26 4.2 14 130 19 00NV-8 Hansen Creek below lineament 35 6.6 26 3 13 110 18 00NV-9 Hansen Creek above dike ridge 39 6.8 27 2 11 130 19 

00NV-10 Osgood Creek above Valley View mine 35 2.9 8.9 2.1 <10 42 15 00NV-11 Tributary to Osgood Creek from south 21 3.4 12 1.9 <10 46 12 00NV-12 Osgood Creek above 2nd road crossing 28 2.5 7.6 2.2 <10 35 14 00NV-13 N. fork Osgood Creek 44 2.6 7.6 2 <10 39 15 00NV-14 S. Fork Osgood Creek 22 2.3 7.1 2.2 <10 29 13 00NV-15 S. Fork Osgood Creek 19 1.5 5 2 <10 23 12 00NV-16 Small tributary to S. fork of Osgood Cr. 13 2.8 9.5 3.6 <10 34 15 00NV-17 Small drainage to south of Osgood Cr. 12 2.6 9.1 1.5 <10 36 11 00NV-18 Approx. 200-300 m downstream from site 17 14 2.8 11 2 <10 49 13 00NV-19 Same creek lower elevation from site 18 18 3.4 13 2.6 <10 61 14 00NV-20 Summer Camp Creek at lower road crossing 32 5.3 20 2.6 14 82 18 00NV-21 Small stream N. of Summer Camp Cr. 27 5.8 22 5.7 21 99 16 00NV-22 500 m upstream of site 20 on Summer Camp Cr. 32 4.9 18 2.5 10 74 19 

00NV-22a Sample duplicate 32 4.9 18 2.6 11 76 19 

00NV-23 Summer Camp Cr. at upper road crossing 33 4.3 16 2.8 <10 64 19 00NV-24 Field blank <0.1 <0.1 <0.1 <0.1 <10 <10 <0.1 00NV-25 Anderson Canyon near Richmond mine 41 4 12 2.2 <10 50 19 
Table 3C. ICP-MS results for water samples collected in 1999. 

[All results shown, except for Be (all < 60 μg/L), Cr (all < 1 μg/L), Ag, Cs, and Bi (all < 10 μg/L), Pr (all < 10 μg/L, except 99NV-23, which was 30 μg/L, and 99NV-25, which except 99NV-23, which was 30 μg/L, and 99NV-25, which was 10 μg/L), Yb (all < 10 μg/L, except 99NV-23, which was 20 μg/L), Tb, Ho, and Tm (all < 5 μg/L), Tl (all < 50 μ20 μg/L), and Th (all < 30 μg/L] 

Field Ca Mg Na K Li Al SiO2 Sc Ti V Fe Mn Co Ni Cu 

no. (mg/L) (mg/L) (mg/L) (μg/L) (μg/L) (μg/L) (mg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) 

99NV-20 36 6.8 24 3100 15 5 27 1 0.52 4.3 < 30 1.1 0.03 0.1 15 99NV-21 22 3.6 9.8 3200 6.8 3 29 1 0.2 1.4 < 30 15 0.09 0.4 9 99NV-22 18 3.2 10 3300 3.5 16 29 0.4 0.1 0.65 99 15 0.2 0.3 4 99NV-23 10 1.9 7.7 2100 2 160 28 0.9 4.9 1.4 80 110 0.3 0.8 6 99NV-24 19 3.0 10 3100 5.6 7 30 1 0.2 1.6 < 30 19 0.09 0.2 4 99NV-25 26 2.7 8.6 3100 6.9 69 27 1 4.2 3.2 68 6.7 0.03 0.3 3 99NV-26 27 4.7 15 3100 10 4 27 1 0.3 3.7 < 30 20 0.04 0.2 4 99NV-27 36 1.1 2.0 460 < 0.8 < 2 19 0.8 < 0.1 0.73 < 30 0.10 < 0.02 0.2 7 99NV-28 33 2.6 7.2 1700 4.6 < 2 28 1 0.1 2.6 < 30 0.47 < 0.02 0.2 3 99NV-29 12 2.6 4.8 1900 < 0.8 < 2 17 0.5 < 0.1 1.1 < 30 1.3 < 0.02 0.1 3 99NV-30 15 2.7 5.5 2100 < 0.8 2 18 0.6 < 0.1 1.3 < 30 0.56 < 0.02 < 0.1 2 99NV-31 15 3.3 7.1 2800 2 6 20 0.4 0.1 1.7 < 30 2.1 < 0.02 < 0.1 2 99NV-32 24 3.2 7.4 2600 3 6 21 0.2 0.1 2.3 < 30 2.3 0.03 0.3 2 99NV-33 35 2.2 6.6 1600 3.6 < 2 24 0.6 < 0.1 3.0 < 30 2.9 < 0.02 0.3 2 

99NV-34 20 3.2 3.7 510 < 0.8 < 2 15 0.2 < 0.1 0.2 < 30 0.51 < 0.02 0.1 1 

99NV-35 14 2.3 7.9 2200 5.5 5 20 0.4 0.2 2.0 < 30 0.37 < 0.02 < 0.1 2 99NV-36 9.4 2.3 6.2 1600 3 9.2 17 0.3 < 0.1 1.8 < 30 0.47 < 0.02 < 0.1 1 99NV-37 26 1.6 3.8 1200 0.9 < 2 21 0.6 < 0.1 1.8 < 30 1.1 < 0.02 1.1 2 

99NV-38 25 3.2 7.9 2200 4.1 < 2 21 0.5 < 0.1 2.6 < 30 3.1 < 0.02 0.2 1 99NV-39 16 3.5 12 3200 5.3 3 25 0.9 < 0.1 3.2 < 30 0.30 < 0.02 0.2 2 99NV-40 26 2.2 5.9 2000 2 2 24 0.4 0.1 2.5 < 30 1.4 < 0.02 0.4 1 99NV-41 < 0.05 < 0.01 < 0.01 < 5 < 0.8 < 2 < 0.5 < 0.1 < 0.1 < 0.2 < 30 < 0.04 < 0.02 < 0.1 0.9 
Table 3C. ICP-MS results for water samples collected in 1999—Continued.

Field Rb Sr Y Mo Cd Sb Ba La Ce Nd Eu Gd Dy 

no. (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) 

99NV-20 0.54 290 0.01 20 < 0.02 0.24 81 < 0.01 < 0.01 < 0.01 0.006 0.005 < 0.005 < 99NV-21 0.60 200 0.03 2.5 < 0.02 0.13 100 < 0.01 0.01 0.02 < 0.005 < 0.005 0.01 < 

99NV-22 0.98 220 0.05 0.84 < 0.02 0.12 96 0.02 0.03 0.03 0.009 0.01 0.01 < 99NV-23 0.90 130 0.1 0.4 < 0.02 3.0 73 0.06 0.08 0.1 0.005 0.04 0.02 99NV-24 0.70 190 0.04 1.6 < 0.02 0.14 83 < 0.01 0.02 0.02 < 0.005 < 0.005 0.006 < 

99NV-25 0.74 160 0.07 5.1 < 0.02 0.22 77 0.04 0.07 0.08 0.009 0.02 0.02 99NV-26 0.50 290 0.04 5.8 < 0.02 0.21 110 < 0.01 0.02 0.02 0.006 0.005 0.005 < 99NV-27 0.50 77 0.07 0.90 0.02 0.07 7.1 < 0.01 < 0.01 0.01 < 0.005 < 0.005 0.006 99NV-28 0.2 130 0.01 13 < 0.02 0.12 59 < 0.01 < 0.01 < 0.01 < 0.005 < 0.005 < 0.005 < 99NV-29 0.2 54 0.01 0.70 < 0.02 0.096 11 < 0.01 < 0.01 0.02 < 0.005 0.005 < 0.005 < 99NV-30 0.2 62 < 0.01 0.87 < 0.02 0.18 15 < 0.01 < 0.01 < 0.01 < 0.005 < 0.005 < 0.005 < 99NV-31 0.3 88 0.02 2.8 < 0.02 0.17 36 < 0.01 < 0.01 0.01 < 0.005 < 0.005 < 0.005 < 99NV-32 0.4 110 0.03 5.7 < 0.02 0.13 49 < 0.01 0.01 0.02 < 0.005 0.01 0.005 < 

99NV-33 0.4 110 0.02 14 < 0.02 0.15 50 < 0.01 < 0.01 0.02 < 0.005 < 0.005 < 0.005 < 99NV-34 0.2 59 0.03 0.96 < 0.02 0.12 20 < 0.01 < 0.01 0.01 < 0.005 < 0.005 0.006 < 

99NV-35 0.2 140 0.01 5.0 < 0.02 0.14 75 < 0.01 < 0.01 < 0.01 < 0.005 < 0.005 < 0.005 < 99NV-36 0.1 130 0.01 8.8 < 0.02 0.10 69 < 0.01 < 0.01 < 0.01 < 0.005 < 0.005 < 0.005 < 99NV-37 0.4 55 0.01 4.4 0.04 0.28 30 < 0.01 < 0.01 < 0.01 < 0.005 < 0.005 < 0.005 < 99NV-38 0.5 120 0.02 12 0.04 0.22 70 < 0.01 < 0.01 < 0.01 0.005 < 0.005 < 0.005 < 99NV-39 0.3 200 0.02 26 < 0.02 0.13 90 < 0.01 < 0.01 < 0.01 < 0.005 < 0.005 < 0.005 < 99NV-40 0.61 95 0.02 8.8 0.02 0.16 42 < 0.01 < 0.01 < 0.01 < 0.005 < 0.005 < 0.005 < 99NV-41 < 0.01 0.06 < 0.01 0.2 < 0.02 0.05 2.3 < 0.01 < 0.01 < 0.01 < 0.005 < 0.005 < 0.005 < 
Table 3D. ICP-MS results for water samples collected in 2000. 

[All results shown, except for the following: Au, Bi, In, Pr, Sm, and Yb (all < 10 μg/L), Cs (all < 10 μg/L, except 00NV-4, which was 40 μg/L, and 00NV-25, which was 10 μg/(all < 50 μg/L, except 00NV-1, which was 60 μg/L), Ga, Ge, and Re (all < 20 μg/L), Co (all < 20 μg/L, except 00NV-19, which was 20 μg/L), Cr and Ni (all < 100 μg/L), Er, EuGd (all < 5 μg/L, except 00NV-16, which was 5 μg/L, and 00NV-18, which was 7 μg/L), and Th (all < 5 μg/L, except 00NV-1, which was 30 μg/L] 

Field Ca Mg Na K Li Al SiO2 V Fe Mn Cu Z

no. (mg/L) (mg/L) (mg/L) (Pg/L) Pg/L) Pg/L) (mg/L) Pg/L) Pg/L) Pg/L) Pg/L) Pg

00NV-1 23 3.7 13 2400 11 <0.5 28 4 10 2.2 0.7 4 00NV-2 16 2.8 8.4 1400 4 <0.5 24 2 42 1.6 <0.5 10 00NV-3 29 4.8 16 2600 12 <0.5 34 4 18 4.7 <0.5 000NV-4 16 2.9 12 1600 13 <0.5 28 4 4.9 1.6 <0.5 1 00NV-5 39 6.6 23 2800 17 <0.5 33 3 42 28 <0.5 1 00NV-6 42 6.8 24 2900 19 <0.5 32 4 32 31 0.6 <000NV-7 27 4.6 16 2900 12 <0.5 34 6.3 21 2.7 0.5 000NV-8 29 4.8 17 2100 12 <0.5 33 3 16 1.1 <0.5 000NV-9 35 5.2 19 1500 11 <0.5 36 1 34 52 <0.5 1 

00NV-10 29 2.4 6.2 1500 2.2 <0.5 27 2 15 0.59 <0.5 000NV-11 19 3 8.9 1500 3.1 <0.5 23 2 6.9 1.2 0.5 1 00NV-12 24 2 5.4 1700 1.1 <0.5 25 2 12 1.2 <0.5 000NV-13 38 2.2 5.6 1500 1.6 <0.5 28 2 23 0.2 <0.5 000NV-14 19 1.9 5.2 1700 1.2 6.4 24 1 14 1.8 <0.5 1 00NV-15 16 1.2 3.7 1500 < 0.4 <0.5 21 1 4.6 0.3 0.5 000NV-16 12 2.3 7.1 2700 5.7 13 27 2 11 4.8 <0.5 000NV-17 11 2.2 7.2 1200 2.7 <0.5 21 0.7 1.7 0.3 <0.5 1 00NV-18 12 2.3 8.1 1600 3.1 2 24 1 78 6.1 <0.5 1 00NV-19 15 2.9 9.6 2000 4.9 0.6 26 2 77 10 <0.5 000NV-20 30 4.4 15 2100 13 <0.5 35 4 20 1.6 <0.5 000NV-21 25 5 16 4600 22 4.3 30 4 18 4.1 <0.5 000NV-22 30 4.2 14 2100 11 <0.5 36 3 26 3.2 <0.5 1 

00NV-22a 30 4.3 14 2100 11 5.2 37 4 31 2.9 <0.5 0

00NV-23 30 3.8 13 2200 9.2 <0.5 36 4 26 11 <0.5 000NV-24 <0.05 <0.01 <0.01 <2 < 0.4 <0.5 < 0.5 <0.1 <1 <0.02 <0.5 2 00NV-25 37 3.4 9.8 1800 5.8 <0.5 36 3 25 0.34 0.9 2 
Table 3D. ICP-MS results for water samples collected in 2000—Continued.

Field Rb Sr Y Mo Ag Cd Sb Ba La Ce Nd D

no. Pg/L) Pg/L) Pg/L) Pg/L) Pg/L) Pg/L) Pg/L) Pg/L) Pg/L) Pg/L) Pg/L) Pg

00NV-1 0.2 270 0.03 6.2 0.05 <0.02 0.08 130 0.03 0.04 0.03 < 0.000NV-2 0.3 180 0.03 4.4 0.02 0.04 0.05 72 0.02 0.01 0.02 < 0.000NV-3 0.5 320 0.04 5.8 0.01 <0.02 0.1 120 0.02 0.03 0.02 0.000NV-4 0.2 200 0.03 0.95 <0.01 <0.02 0.06 91 0.02 < 0.01 0.02 < 0.000NV-5 0.68 400 0.05 16 <0.01 <0.02 0.1 120 < 0.01 0.02 < 0.01 < 0.000NV-6 0.69 390 0.04 21 <0.01 <0.02 0.2 100 0.02 0.05 0.02 < 0.000NV-7 0.56 310 0.04 5.4 <0.01 <0.02 0.2 120 0.02 0.04 0.03 0.000NV-8 0.69 300 0.03 18 <0.01 <0.02 0.1 94 0.01 0.02 0.01 < 0.000NV-9 1 370 0.06 18 <0.01 <0.02 0.1 100 0.01 0.03 0.02 < 0.0

00NV-10 0.52 100 0.02 8.5 <0.01 <0.02 0.08 44 < 0.01 < 0.01 < 0.01 < 0.000NV-11 0.3 140 0.02 5.9 <0.01 0.04 0.08 46 0.01 0.02 0.02 < 0.000NV-12 0.54 84 0.02 5.4 <0.01 <0.02 0.07 44 < 0.01 < 0.01 < 0.01 < 0.000NV-13 0.54 96 0.01 4.1 <0.01 0.02 0.1 51 < 0.01 < 0.01 < 0.01 < 0.000NV-14 0.5 79 0.02 5.2 <0.01 <0.02 0.06 40 < 0.01 < 0.01 0.01 < 0.000NV-15 0.73 51 0.01 4.6 <0.01 <0.02 0.05 24 < 0.01 < 0.01 < 0.01 < 0.000NV-16 0.3 130 0.04 3.9 <0.01 <0.02 0.05 81 0.03 0.04 0.04 < 0.0

00NV-17 0.1 110 0.01 1.5 <0.01 <0.02 0.02 65 < 0.01 < 0.01 0.01 < 0.000NV-18 0.55 140 0.03 1.1 <0.01 <0.02 0.03 78 0.02 0.04 0.02 < 0.0

00NV-19 0.57 150 0.04 2.1 <0.01 <0.02 0.04 76 0.02 0.03 0.03 0.000NV-20 0.4 230 0.03 15 <0.01 <0.02 0.1 90 0.01 0.01 0.01 < 0.000NV-21 1.2 220 0.03 20 <0.01 <0.02 0.08 93 0.02 0.03 0.03 < 0.000NV-22 0.4 210 0.03 10 <0.01 <0.02 0.09 88 0.01 0.02 0.02 < 0.0

00NV-22a 0.4 220 0.03 11 <0.01 <0.02 0.09 90 0.01 0.01 0.02 < 0.0

00NV-23 0.5 200 0.02 6.1 <0.01 <0.02 0.08 90 0.01 0.02 0.01 < 0.0

00NV-24 < 0.01 < 0.02 < 0.01 0.09 <0.01 <0.02 <0.02 0.2 < 0.01 < 0.01 < 0.01 < 0.0

00NV-25 0.3 160 0.02 17 <0.01 <0.02 0.09 65 < 0.01 < 0.01 < 0.01 < 0.0
Table 4. Results of sulfur isotopic analyses of water samples. 

[All values are given in permil deviations relative to Cañon Diablo Troilite 

(CDT). na, not analyzed] 

Sample no. G34S SO4 Sample no. G34S SO4

99NV-20 8.7 00NV-1 8.09

99NV-21 11.8 00NV-2 6.89

99NV-22 13.9 00NV-3 8.70

99NV-23 9.7 00NV-4 8.09

99NV-24 11.6 00NV-5 10.45

99NV-25 9.4 00NV-6 7.83

99NV-26 na 00NV-7 9.56

99NV-27 12.3 00NV-8 6.95

99NV-28 10.6 00NV-9 8.20

99NV-29 15.3 00NV-10 8.41

99NV-30 14.9 00NV-11 5.41

99NV-31 13.5 00NV-12 9.05

99NV-32 11.9 00NV-13 10.71

99NV-33 10.1 00NV-14 8.76

99NV-34 7.2 00NV-15 8.40

99NV-35 6.6 00NV-16 7.71

99NV-36 7.3 00NV-17 7.28

99NV-37 6 00NV-18 8.98

99NV-38 7.2 00NV-19 na

99NV-39 9 00NV-20 8.26

99NV-40 8.4 00NV-21 6.58

00NV-22 8.95

00NV-23 8.64

00NV-25 11.42

Table 5. Comparison of 1999 and 2000 samples from the same locations. 

[In “Percent difference” rows, the percentage of difference is calculated by the following formula: %diff. = (1999 

value – 2000 value)/(average of 1999 and 2000 values). Values in excess of ± 25 percent appear in bold] 

ANION DATA AND SELECTED FIELD PARAMETERS 

Sample pH SpC T F Cl NO3

 

SO4

no. (μS/cm) (°C) (mg/L) (mg/L) (mg/L) (mg/L)

00NV-25 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

8.33 270 11.3 0.19 5.5 0.1 12

99NV-28 8.23 265 9.7 0.17 5.37 0.39 13.3

Percent difference -1.9 -15 -11 -2.4 120 10

00NV-3 8.3 300 16 0.31 8.5 0.06 19

99NV-26 8.11 310 14.6 0.29 7.69 0.73 18.1

Percent difference 3.3 -9.2 -6.7 -10 170 -4.9

00NV-23 8.28 270 17.1 0.24 5.3 0.06 14.2

99NV-25 8.14 240 14.4 0.2 4.46 1.39 12.3

Percent difference -12 -17 -18 -17 180 -14

00NV-10 8.23 220 11.5 0.16 2.98 0.1 18.2

99NV-40 8.31 230 18.9 0.18 3.15 1.17 18.4

Percent difference 4.4 49 12 5.5 170 1.1

00NV-6 7.75 480 18.1 0.3 13.1 38

99NV-20 7.061 410 11.9 0.33 13.5 4.2 40.5

Percent difference -16 -41 9.5 3.0 6.4

14  Geoenvironmental Investigations of the Humboldt River Basin, Northern Nevada
Table 5. Comparison of 1999 and 2000 samples from the same locations—Continued.

ORIGINAL ICP-MS DATA 

Major cations Other major and minor constituents 

Sample Ca Mg Na K Li SiO2 Ba Sr Rb V Mn Fe Cu As Y 

no. (mg/L) (mg/L) (mg/L) Pg/L) Pg/L) (mg/L) Pg/L) Pg/L) Pg/L) Pg/L) Pg/L) Pg/L) Pg/L) Pg/L) Pg/L) P

00NV-25 37 3.4 9.8 1800 5.8 36 65 160 0.3 3 0.34 25 0.9 0.8 0.02 199NV-28 33 2.6 7.2 1700 4.6 28 59 130 0.2 2.6 0.47 < 30 3 0.8 0.01 1

Percent difference -11 -27 -31 -6 -23 -25 -10 -21 -40 -14 32 108 0 -67 -2

00NV-3 29 4.8 16 2600 12 34 120 320 0.5 4 4.7 18 <0.5 2.8 0.04 

99NV26 27 4.7 15 3100 10 27 110 290 0.50 3.7 20 < 30 4 3.3 0.04 

Percent difference -7 -2 -6 18 -18 -23 -9 -10 0 -8 124 16 0 

00NV-23 30 3.8 13 2200 9.2 36 90 200 0.5 4 11 26 <0.5 1 0.02 

99NV25 26 2.7 8.6 3100 6.9 27 77 160 0.74 3.2 6.7 68 3 1 0.07 

Percent difference -14 -34 -41 34 -29 -29 -16 -22 39 -22 -49 89 0 111 -1

00NV-10 29 2.4 6.2 1500 2.2 27 44 100 0.52 2 0.59 15 <0.5 1 0.02 

99NV40 26 2.2 5.9 2000 2 24 42 95 0.61 2.5 1.4 < 30 1 1 0.02 

Percent difference -11 -9 -5 29 -10 -12 -5 -5 16 22 81 0 0 

00NV-6 42 6.8 24 2900 19 32 100 390 0.69 4 31 32 0.6 4.2 0.04 2

99NV20 36 6.8 24 3100 15 27 81 290 0.54 4.3 1.1 < 30 15 4.5 0.01 2

Percent difference -15 0 0 7 -24 -17 -21 -29 -24 7 -186 185 7 -120 -
Table 5. Comparison of 1999 and 2000 samples from the same locations—Continued.

ICP-MS DATA NORMALIZED TO CHLORIDE CONCENTRATION 

Major cations Other major and minor constituents 

Sample no. Ca Mg Na K Li SiO2 Ba Sr Rb V Mn Fe Cu As Y 

00NV-25 6.7 0.62 1.78 327 1.05 6.55 11.8 29.1 .055 0.55 .062 4.55 0.16 0.15 .004 399NV-28 6.1 0.48 1.34 316 0.86 5.21 11.0 24.2 .037 0.48 .087 0.56 0.15 .002 2

Percent difference -9 -24 -28 -3 -21 -23 -7 -18 -38 -12 34 109 2 -65 -24 

00NV-3 3.4 0.56 1.88 306 1.41 4 14.1 37.6 .059 0.47 0.55 2.12 0.33 0.00 0

99NV26 3.5 0.61 1.95 403 1.30 3.51 14.3 37.7 .065 0.48 2.60 0.52 0.43 .005 0

Percent difference 3 8 4 27 -8 -13 1 0 10 2 130 26 10 10 

00NV-23 5.7 0.72 2.45 415 1.7 6.79 17. 37.7 .094 0.75 2.07 4.91 0.19 .004 1

99NV25 5.8 0.61 1.93 695. 1.5 6.05 17. 35.9 .166 0.72 1.50 15.2 0.67 0.22 .016 1

Percent difference 3 -17 -24 50 -11 -11 2 -5 55 -5 -32 103 17 122 -1 

00NV-10 9.7 0.81 2.08 503 0.74 9.06 14.8 33.6 .174 0.67 0.20 5.03 0.34 .007 2

99NV40 8.3 0.70 1.87 635 0.63 7.62 13.3 30.2 .194 0.79 0.44 0.32 0.32 .006 2

Percent difference -16 -14 -10 23 -15 -17 -10 -11 10 17 77 -6 -6 -2 

00NV-6 3.21 0.52 1.83 221 1.45 2.44 7.6 29.8 .053 0.31 2.37 2.44 .046 0.32 .003 1

99NV20 2.67 0.50 1.78 230 1.11 2.0 6 21.5 .04 0.32 .081 1.11 0.33 .001 1

Percent difference -18 -3 -3 4 -26 -20 -24 -32 -27 4 -187 184 4 -122 -8 
are fewer instances of exceeding this 25-percent threshold 

for the cation data when normalized to chloride, suggesting 

that evaporation likely does not explain the annual variations and there must be other processes active in the system. 

Another reason that evaporation probably plays a minor role 

in the differences is that the trace element results are more 

variable than the major elements, even when normalized to 

chloride. According to weather records from Winnemucca, 

Nev., some 40 km to the southwest of the Osgood Mountains 

in the Humboldt River valley, 1999 was drier (5.33 inches 

total precipitation in 1999; 9.85 inches in 2000) and slightly 

cooler than 2000 (48.7°F average in 1999; 49.6°F in 2000). If 

evaporation was a major factor in the difference between 1999 

and 2000 samples, then we should expect to see slightly higher 

concentrations of major and trace elements for 1999 samples 

than for 2000 samples. In table 5, positive percent differences 

should be observed between samples from 1999 to 2000 if 

greater evaporation occurred in 1999. In fact, when all the 

differences are considered (not just those above 25 percent), 

there are more negative than positive differences, indicating 

that samples were slightly more concentrated in 2000 than in 

1999. Thus, water-rock interactions such as precipitation, dissolution, and adsorption/ion exchange might be occurring in 

the system. Adsorption may be the least important of these, 

as it depends strongly on pH. The pH differences between the 

1999 and 2000 samples are not significant in any of the sample 

pairs. The greatest difference is 0.7 pH units at one sample 

site, but the rest of the sample pairs are within 0.2 pH units of 

each other. 

Hydrologic differences also could be the cause of the 

observed chemical differences between 1999 and 2000. For 

example, if precipitation was different in timing or amount 

(which it was), different ground-water sources could be contributing to the streams in different years. For example, if 

some springs dried up or contributed less flow to streams in 

one year compared to the other, the resultant chemistry of the 

streams would be different to the extent that the loads from 

those springs was decreased. Thus, a temporal hydrologic difference could be an indicator of relatively local scale spatial 

differences in rock chemistry or mineralogy, as the springs that 

decreased (or increased) their flow to streams could indicate 

spatial differences in rock properties. Temporal hydrologic 

differences also could be the result of compartmentalization 

of ground-water flow. For example, relatively isolated packets 

of water could be discharging at different proportions between 

the two sampling years. Another possibility could be that the 

composition of discharging waters could change if there were 

“layered” chemical properties of the ground water. In this 

scenario, there could be a layer of water with one chemical 

character sitting atop a layer of water with a different chemical character. The two waters could be in hydrologic continuity with each other, but mixing is limited in the laminar flow 

regime in the ground. In this study, no data were collected to 

evaluate these possible hydrologic effects, although methods 

exist, such as the in-stream tracer methods as described by 

Kimball and others (1999).

The variations between 1999 and 2000 sample sites 

are small relative to the variations in parameters observed 

throughout the Osgood Mountains study area, so the full data 

set from the two sampling years can be interpreted as one, and 

major variations in water chemistry between sample sites are 

likely due to processes other than those brought about by temporal variations.

Spatial Variability

Figure 3 shows the study area in the Osgood Mountains. 

Sample locations from the two sampling trips are shown on 

the figure. By comparing the chemical and hydrologic variations throughout the study area, we can follow processes 

occurring at a variety of spatial scales. The following discussion is organized by extent of spatial scale and keyed to locations marked A through E on the map (fig 3).

Variations at Tens of Kilometers

Although there were no obvious compositional differences in the intrusive rocks between the two lobes of the stock, 

there appears to be a compositional and isotopic difference 

in spring and stream waters collected from the south vs. the 

north lobe. More dilute waters with isotopically lighter sulfatesulfur were found in the southern lobe, and somewhat more 

concentrated waters with heavier, more variable sulfate-sulfur 

isotopic compositions were found in the northern lobe. Figure 

4 shows this relationship, using sulfate-sulfur isotope compositions as an example. Similar variations were observed in the 

aqueous concentrations of a number of trace metals as well. 

This separation is readily apparent at a sample density of 2 per 

square kilometer, but it is still apparent at average sample densities slightly below 1 per square kilometer. This trend is likely 

due to subtle lithochemical variations in the Osgood intrusive 

rocks.

Variations at Hundreds to Thousands of Meters

Between points A and B along Granite Creek (fig. 3), 

changes were observed in the chemistry of surface water. 

Upstream, near point A, conductivity values were less than or 

equal to 210 μS/cm. By the time Granite Creek reached point 

B, conductivity increased to 240 μS/cm and flow increased 

by more than five times. The creek follows an alteration zone 

that is defined by an abundance of sulfide (and other) minerals in the rocks (Neuerberg, 1966). No tributaries to Granite 

Creek exist other than those shown on the figure, so any 

chemical changes from A to B must be explained by mixing 

of upstream samples at A with ground-water discharge to 

produce the observed chemistry at B. The small tributaries 

near A were more dilute than the main stream at A and do not 

account for the increase in solute load from A to B. Therefore, 

Hydrogeochemical Investigations in the Osgood Mountains, North-Central Nevada  17
the observed changes (more than double) in the concentrations of Cl, B, K, Ba, Mg, Na, Sr, Mo, W, U, and Mn can be 

attributed to weathering of altered rocks in the ground-water 

environment and discharge of that ground water to Granite 

Creek. Ground water discharging along this several-kilometer 

reach of stream should reflect the chemical signature of rock 

alteration. The alteration is characterized by sulfide minerals 

(mostly pyrite) as well as enrichments of gold (Neuerberg, 

1966), but dissolved sulfate does not increase along Granite 

Creek from point A to B. It is possible that other minerals are 

dissolving more rapidly than the sulfides and contributing the 

elements listed above to Granite Creek, or perhaps the exposed 

sulfide minerals have already been weathered and the listed 

elements are derived from minerals that dissolve more slowly. 

Either way, it is somewhat surprising that dissolved sulfate 

does not increase along Granite Creek. Because Granite Creek 

follows a mapped alteration zone (Neuerberg, 1966), which is 

in turn related to a bounding strike-slip fault, it is inferred that 

the structure is hydraulically conductive.

The spring sample collected at point E in the northern 

lobe of granodiorite (fig. 3) is unusual from a geomorphological point of view. The spring is located on a ridge crest, rather 

than in a valley. The localization of the spring along the ridge 

is controlled by a zone of east-west-trending fractures in the 

rock that extend to the west for at least several kilometers. 

Although these fractures are obviously hydraulically conductive, their connection to crosscutting fractures in the area must 

be limited, or else the spring would not be found on a ridge 

top.

Variations at Meters to Tens of Meters

The fault at point C (fig. 3) is one of the principal bounding faults for Osgood Mountains intrusive rocks. In today’s 

stress regime, it is also expected to be a hydraulically conductive fracture set because it is oriented subparallel to the 

present-day maximum principal stress direction as shown by 

17'30" 117 ̊15'

41 ̊7'30"

10'

12'30"

Adam

Peak

SpC < 200 

200 < SpC < 350 

SpC > 350 

1 km

A

B

C

D

E

Figure 3. Index map of the Osgood Mountains study area. Shaded 

area represents outcrop of two large granodiorite intrusive-rock 

bodies. Altered areas shown by stippled pattern; major faults shown 

by heavy dashed lines; round symbols show locations of water-sampling sites, coded with specific-conductance values (SpC, in μS/cm). 

Letters A through E correspond to locations mentioned in the text.

5

41.13

41.15

41.17

41.19

41.21

7 9 11 13 15 17

δ34S vs. CDT

Latitude, degrees North

Figure 4. Variation in sulfate-sulfur δ34S (‰) as a function of latitude. 

Values of δ34S are reported relative to Cañon Diablo troilite (CDT) 

standard, which has a value of 0 ‰. This plot demonstrates a regional 

compositional variation between the southern and northern lobes 

of the granodiorite intrusive rocks in the Osgood Mountains. Similar 

variations are observed for a number of other chemical parameters.

18  Geoenvironmental Investigations of the Humboldt River Basin, Northern Nevada
Zoback and others (1990). The fault is regionally extensive 

(many kilometers), but the hydrologic effects on Osgood 

Creek are localized within a very narrow zone. As Osgood 

Creek crossed the fault, flow increased by more than a factor 

of 30, and specific conductivity decreased from more than 300 

μS/cm to about 250 μS/cm. Ground-water discharge from the 

fault provided water to Osgood Creek that was more dilute 

than the headwaters.

There were two springs at point D (fig. 3), approximately 

20 m apart from each other. Despite their proximity to each 

other, one had a conductivity of 120 μS/cm, whereas the other 

had a conductivity of 280 μS/cm. Because of the thin soil 

cover, ground-water flow is predominantly in bedrock, and the 

locations of these springs are likely structurally controlled. 

The difference in water chemistry between these two adjacent 

springs is attributed either to differences in residence times of 

the spring waters in the ground or to local variations in lithochemistry along different ground-water flow paths. Regardless 

of their cause, these chemical differences demonstrate the 

compartmentalization of flow by unconnected fracture sets.

Conclusions

The average sample density in the Osgood Mountains 

study area was approximately 2 per square kilometer. Many of 

these samples were collected while walking along the drainages and monitoring conductivity and temperature, and measuring hydraulic heads of ground water beneath streambeds 

using a device described by Wanty and Winter (2000). At the 

same time, geologists were nearby observing fracture orientation, density, and kinematic indicators (if any). The continuous interaction between geologists and chemists led to many 

of the observations described in this paper. With little prior 

knowledge of the hydrology of the Osgood Mountains, we collected several important pieces of data that will help unravel 

the hydrology and chemistry of ground and surface waters in 

the region. Many of the features described in this paper would 

have been missed without a geologic context or perhaps with a 

less dense sampling pattern. It should be noted, however, that 

the sample density was not predetermined. Rather, samples 

were collected based on observations of geologic, hydrologic, 

and geochemical parameters as field work progressed. This 

approach, even though somewhat more time consuming than 

traditional methods of surface-water investigations, is needed 

to fully characterize the ground-water/surface-water flow systems.

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Manuscript approved for publication April 17, 2003

Published in the Central Region, Denver, Colorado

Editing, layout, photocomposition—Richard W. Scott, Jr.

Graphics by the authors

Hydrogeochemical Investigations in the Osgood Mountains, North-Central Nevada  19