principal facts for gravity stations in the humboldt · pdf fileprincipal facts for gravity...

Principal Facts for Gravity Stations in The Humboldt House Geothermal Area, Pershing County, Nevada

By Brian G. Duffrin, David L. Berger, and Donald H. Schaefer

U.S. GEOLOGICAL SURVEY

Open-File Report 85-162

Prepared in cooperation with the

U.S. BUREAU OF LAND MANAGEMENT

Carson City, Nevada

1985

UNITED STATES DEPARTMENT OF THE INTERIOR

DONALD PAUL MODEL, Secretary

GEOLOGICAL SURVEY

Dallas L. Peck, Director

For additional information Copies of this report may be write to: purchased from:

U.S. Geological Survey Open-File Services SectionRoom 227, Federal Building U.S. Geological Survey705 North Pla/a Street Box 25425, Federal CenterCarson City, NV 89701 Denver, CO 80225

Call (303) 236-7476 for ordering information

CONTENTS

Page

ADS tract -- -- -- -- j^

Introduction 1

Principal facts for gravity stations 5

References cited 11

ILLUSTRATION

Figure 1. Map showing location of gravity stations 3

^^^

CONVERSION FACTORS AND ABBREVIATIONS

"Inch-pound" units of measure used in this report may be converted to International System (metric) units by using the following factors:

Multiply By To obtain

Feet (ft) 0.3048 Meters (m)

Miles (mi) 1.609 Kilometers (km)

ALTITUDE DATUM

The term "National Geodetic Vertical Datum of 1929" replaces the formerly used term "mean sea level" to decribe the datum for altitude measurements. The datum is derived from a general adjustment of the first-order leveling network of both the United States and Canada. For convenience in this report, the datum is referred to as "sea level."

^v

PRINCIPAL FACTS FOR GRAVITY STATIONS IN

THE HUMBOLDT HOUSE GEOTHERMAL AREA,

PERSHING COUNTY, NEVADA

By Brian G. Duffrin, David L. Berger, and Donald H. Schaefer

ABSTRACT

Principal facts for 172 gravity stations in and near Humboldt House, Nev., are tabulated; they consist of latitude, longitude, altitude, observed gravity, free-air anomaly, terrain correction, and Bouguer anomaly values at a bedrock density of 2.67 grams per cubic centimeter.

INTRODUCTION

The Humboldt House study area, about 50 miles southwest of Winnemucca and 100 miles northeast of Reno, is one of Nevada's many promising geothermal areas. The area of study, about 500 square miles, lies in the Humboldt River valley between Lovelock and Imlay. The purpose of the geophysical study for which data are reported herein, which was made in cooperation with the U.S. Bureau of Land Management, was to determine aspects of the geology that may control, affect, or delineate the geothermal system in the area.

During June and July 1981, gravity measurements were made at 172 stations in and near Humboldt House.

The latitude and longitude for most stations in the study area were obtained using the Loran navigation system. Peripheral bedrock stations were surveyed with an electronic transit for position and altitude. Additionally, bench marks, section corners, and road intersections were used to locate stations.

Most altitudes were determined using altimeters or topographic maps.

The gravity observations were made with a Worden^ temperature-controlled gravimeter with a scale factor of 0.1907 milliGal per scale division.

* Use of brand names in this report is for descriptive purposes only and does not constitute endorsement by the U.S. Geological Survey.

-1-

Two base stations in the study area were established; gravity remeasurements were made at one or the other at the beginning, middle, and end of each working day in order to correct for any gravimeter drift. The base stations were related to a U.S. Department of Defense gravity station in Winnemucca by numerous repeat measurements. This gravity station has a standard absolute value of 979,810.48 milliGals (Gravity Services Branch, 1970).

Principal facts for each of the 172 stations are listed in the following table. Figure 1 shows the location of the stations. In addition, Schaefer (in press) discusses details regarding the collection, correction, reduction, interpretation, and limitations of the data. A map showing Bouguer gravity anomalies in the Humboldt House area is also given in Schaefer f s report.

The data listed in the following table are available on magnetic tape from the U.S. Geological Survey, 705 N. Plaza St., Room 224, Carson City, Nev. 89701.

118°30'

40°15'

FIGURE 1.-Location of gravity stations.

-3-

PRINCIPAL FACTS FOR

GRAVITY STATIONS

-5-

Site: Data are listed by valley, in order of increasing latitude (that is, fromnorth to south).

Terrain corrections: "Hand" indicates manual correction within a radius of1.42 miles, at a bedrock density of 2.67 g/cm^ (grams per cubic centimeter)."Comp" indicates computer correction between radii of 1.42 and 103.6 miles,at a bedrock density of 2.67 g/cm^. (See Schaefer, 1983, page 8).

Bouguer anomaly: Complete Bouguer anomaly at a bedrock density of 2.67 g/crn^.

Site

HH158HH159HH157HH156HH170






Latitude

(deg min)

40 17.9040 18.6740 18.7040 18.7140 19.59

40 19.8040 20.5540 20.7840 23.4940 25.70

40 26.5040 27.1340 27.8840 30.0440 30.04

40 30.0440 30.0440 30.0440 30.0540 30.06

40 30.1340 30.1440 30.1540 30.2040 30.22

40 30.2240 31.4340 31.7940 31.8240 31.89

Longitude

(deg min)

118 21.00118 20.70118 22.92118 23.03118 10.29

118 23.60118 22.10118 24.45118 21.91118 17.83

118 19.99118 21.90118 19.92118 21.94118 21.54

118 21.11118 20.45118 19.70118 20.64118 20.04

118 16.32118 15.84118 15.40118 14.98118 17.24

118 14.76118 29.64118 27.44118 27.03118 26.24

Altitude (feetabovesealevel)

41274156414841166542

41974165433142804145

42774402425645104413

43554212427043014294

46444751484449984476

50944594448044594438

Observedgravity(mGal)

979812.49979808.20979808.35979812.16979672.87

979815.43979808.92979807.53979806.10979817.73

979802.76979804.86979807.16979814.53979818.02

979819.12979818.83979811.61979817.67979813.59

979796.68979792.68979787.27979779.32979799.94

979773.52979797.68979807.31979810.41979817.57

Free-air

anomaly(mGal)

5.092.391.732.53

89.94

11.781.15

15.034.770.42

-3.349.58

-2.9625.0719.44

15.091.36

-0.418.553.79

19.6825.7229.0435.497.02

38.6914.0412.4213.5018.58

Terrain corrections

Hand(mGal)

0.020.020.000.007.13

0.000.010.110.020.00

0.000.000.000.500.32

0.360.000.480.101.30

1.542.022.042.580.44

1.860.020.140.060.09

Comp(mGal)

0.490.410.290.313.71

0.330.360.400.401.23

0.530.380.560.390.41

0.440.550.560.470.51

1.621.922.282.621.16

2.800.310.360.380.39

Bougueranomaly(mGal)

-136.51-140.28-140.81-138.90-124.06

-132.40-141.89-133.58-142.17-141.08

-150.07-141.60-148.94-129.30-131.76

-134.06-143.12-146.39-138.97-142.24

-137.02-133.86-133.35-131.32-145.48

-131.95-143.77-141.31-139.57-133.72

-6-

Site








Latitude

(deg min)

40 31.9440 31.9440 31.9840 32.0540 32.10

40 32.2240 32.4040 32.5940 32.6840 32.82

40 32.9540 32.9640 33.0340 33.2040 33.37

40 33.5540 33.7440 33.8940 33.9140 34.12

40 34.1240 34.2540 34.3640 34.5140 34.57

40 34.7640 34.7640 34.8140 34.8240 34.96

40 35.0040 35.0040 35.0740 35.1440 35.23

Longitude

(deg min)

118 28.54118 26.65118 25.85118 28.38118 25.31

118 29.33118 24.86118 24.49118 30.05118 24.19

118 23.79118 23.37118 22.80118 22.47118 22.09

118 21.74118 21.37118 21.03118 22.79118 24.21

118 20.44118 20.07118 19.77118 19.39118 21.08

118 18.28118 16.94118 17.37118 17.78118 24.36

118 20.00118 20.00118 16.49118 15.89118 16.83

Altitude (feet above sea level)

45314475443045344394

45634389437746244346

43494324430942884270

42514235417742874519

42024188418141434209

42094194416041574546

41534237420942584171

Observed gravity (mGal)

979802.25979812.73979820.08979801.11979825.54

979798.98979826.38979826.38979795.23979828.77

979826.61979825.40979823.79979822.99979822.34

979821.77979821.67979822.10979824.32979819.85

979821.97979822.16979821.91979822.69979823.22

979816.28979822.48979822.65979821.61979820.77

979817.47979830.20979819.83979825.03979820.02

Free- air

anomaly (mGal)

11.9317.1520.2110.9122.11

11.2622.0320.6212.5519.75

17.6814.1110.987.965.36

2.740.85

-4.408.1325.16

-2.52-3.84-4.91-7.93-1.28

-8.50-3.71-6.82-8.1627.36

-12.947.68

-5.424.29

-9.04

Terrain corrections

Hand (mGal)

0.020.070.090.070.12

0.060.080.050.020.11

0.010.000.000.000.00

0.000.000.000.000.19

0.000.000.000.000.00

0.000.010.000.000.39

0.000.000.050.120.01

Comp (mGal)

0.330.360.390.330.42

0.340.410.390.340.41

0.380.360.340.330.32

0.330.330.360.370.43

0.350.380.400.460.33

0.550.950.820.690.51

0.370.331.051.300.90

Bouguer anomaly (mGal)

-143.70-136.47-131.82-144.77-128.63

-145.42-128.59-129.63-146.26-129.36

-131.67-134.41-137.04-139.35-141.34

-143.31-144.64-147.87-139.10-129.79

-146.85-147.66-148.47-150.13-145.88

-152.88-147.16-149.24-150.60-128.23

-155.57-137.87-149.24-140.90-151.75

-7-

Latitude

Site








(deg min)

4040404040

4040404040

4040404040

4040404040

4040404040

4040404040

4040404040

35.4235.6135.7036.0536.30

36.5736.5936.5936.7136.83

36.8336.8536.8936.8936.92

36.9436.9436.9536.9837.03

37.0937.1037.2037.2337.25

37.3737.4037.5337.8337.87

38.0738.1738.2238.3138.43

Longitude

(deg

118118118118118

118118118118118

118118118118118

118118118118118

118118118118118

118118118118118

118118118118118

min)

17.2817.5515.5618.1118.40

18.6619.2018.9011.9525.95

25.6526.4025.2024.8019.47

24.4024.0011.9923.5623.15

22.7119.7520.3522.1812.18

21.4221.2812.3712.5328.08

12.645.0012.545.3012.73

Altitude (feet above Observed sea gravity

level) (mGal)

41514149425741464152

41604147414948964922

48455023476846774137

45964507479644344355

43004153415542144630

41514134450843864503

43074637429044634246

979818979819979825979816979816

979816979817979817979808979800

979805979793979810979816979818

979820979824979814979826979829

979830979819979821979832979824

979827979827979831979837979802

979839979822979839979831979841

.96

.79

.50

.92

.41

.67

.32

.04

.71

.96

.49

.82

.65

.20

.38

.83

.14

.53

.42

.83

.93

.00

.02

.32

.52

.28

.16

.36

.48

.61

.60

.71

.87

.54

.40

Free-

air anomaly (mGal)

-12.27-11.90

3.83-15.71-16.03

-15.42-16.02-16.1145.6040.11

37.4042.4335.2432.23

-16.39

29.1824.1141.6619.4815.38

11.23-14.54-12.48

4.3235.60

-6.85-8.6130.5524.760.83

19.0933.0717.5425.3414.62

Terrain corrections

Hand (mGal)

0.000.000.100.000.00

0.010.000.001.190.50

0.480.650.250.180.00

0.120.080.000.130.17

0.130.000.000.011.54

0.090.000.960.810.04

0.100.480.080.440.03

Comp (mGal)

0.730.621.230.470.40

0.340.320.341.870.77

0.750.790.700.650.30

0.590.541.650.480.45

0.410.280.270.381.39

0.340.341.181.022.08

0.910.630.870.680.76


-154.47-154.15-141.41-158.01-158.61

-158.31-158.49-158.64-119.85-128.01

-128.12-128.98-127.92-127.92-158.54

-128.32-130.42-121.77-132.56-133.94

-136.29-157.27-155.28-140.39-120.85

-149.36-150.63-122.50-124.41-152.07

-128.18-125.44-129.22-127.18-130.78

-8-

Latitude

Site





HH9HH86HH27HH87HH88



(deg min)

4040404040

4040404040

4040404040

4040404040

4040404040

4040404040

4040404040

38.4938.6038.7738.8138.86

38.9539.0139.1139.2439.25

39.2639.2839.3839.4139.56

39.5839.6039.7239.8339.83

39.8339.9740.0840.3040.52

40.7840.8140.9941.3241.48

41.5241.5441.6041.6241.68

Longitude

(deg

118118118118118

118118118118118

118118118118118

118118118118118

118118118118118

118118118118118

118118118118118

min)

5.776.1812.856.5822.24

6.9513.117.3713.3613.33

7.779.4610.088.188.57

28.0510.453.7811.2011.20

11.2011.5712.1712.4412.75

20.8313.0713.1514.9015.27

13.3214.127.1513.6915.47


43954350418943214207

43144162429341574154

42744235425342434218

54534241468741724176

41764211417242154211

41594200419441724224

41494211420542124162


979830979828979842979827979832

979826979842979826979842979842

979826979838979840979829979832

979771979844979822979844979853

979844979847979843979847979849

979833979852979854979853979847

979857979856979832979855979848

.44

.97

.21

.56

.32

.71

.48

.20

.21

.97

.32

.72

.84

.22

.22

.42

.21

.65

.82

.27

.37

.01

.80

.31

.13

.19

.02

.94

.43

.25

.08

.00

.42

.92

.13

Free- air

anomaly (mGal)

17.5811.729.577.271.23

5.556.942.835.866.32

0.949.6513.310.701.12

56.3815.2235.409.0017.83

8.9314.647.6114.8315.95

-5.2617.3819.4615.3913.86

16.5821.30-2.9421.198.61

Terrain corrections

Hand (mGal)

0.200.080.030.040.00

0.030.000.030.000.00

0.020.040.190.040.04

1.470.221.410.000.35

0.340.080.000.180.12

0.000.080.060.200.46

0.100.170.010.140.57

Comp (mGal)

0.740.790.650.760.37

0.720.560.680.470.48

0.650.680.600.620.59

1.190.520.430.480.48

0.480.400.380.320.29

0.190.270.260.230.20

0.310.240.250.260.22


-132.79-137.18-133.98-140.71-143.25

-142.24-135.81-144.28-136.81-136.24

-145.55-135.46-132.34-144.74-143.48

-128.55-130.06-124.09-134.17-125.14

-134.05-129.87-135.66-129.80-128.64

-148.28-126.90-124.63-127.84-130.93

-125.88-123.28-147.47-123.44-133.91

-9-

Latitude

Site


HH38HH4HH11HH2HH10

HH8HH36HH39HH7HH32

HH6HH35HH41HH12HH40

HH13HH5HH34HH3HH33



HH17WINN

BASE

(deg min)

4040404040

4040404040

4040404040

4040404040

4040404040

4040404040

4040404040

4040

41.7142.1442.2642.3842.50

42.6142.6442.6842.6842.70

42.7342.7542.7642.7642.77

42.7942.8042.8142.8142.82

42.8342.8342.8442.8742.88

42.9243.1243.1243.2443.28

43.6143.6743.8443.9644.26

44.4454.23

Longitude

(deg

118118118118118

118118118118118

118118118118118

118118118118118

118118118118118

118118118118118

118118118118118

118117

min)

12.6822.448.179.6315.81

24.8018.6325.1716.1624.07

22.8321.9125.9321.5516.54

21.0020.3128.1926.0426.29

27.3119.6418.9117.3617.91

13.8728.4110.127.77

29.04

21.7429.3529.648.8830.01

21.8848.21


41684314418441944211

45514163454741684426

42394280464742424168

42174181482846394656

47534168415941674158

51564927427442004984

42515143523942905491

42534298


979860979832979842979854979842

979833979837979832979841979833

979832979832979827979833979839

979834979835979816979826979827

979820979837979837979836979836

979803979811979858979850979808

979832979799979795979859979780

979833979839

.49

.97

.37

.96

.35

.28

.11

.58

.95

.79

.30

.87

.77

.62

.36

.13

.72

.61

.95

.56

.06

.46

.46

.54

.32

.27

.86

.06

.80

.96

.75

.41

.13

.31

.77

.48

.03

Free- air

anomaly (mGal)

21.497.064.0617.416.22

28.94-3.7427.761.50

17.57

-1.552.85

32.230.02

-1.22

-1.87-3.6838.0130.5932.78

34.38-3.21-4.07-4.28-5.37

55.3342.1026.9312.5344.32

-1.2849.1453.6228.4262.32

-1.60-6.42

Terrain corrections

Hand (mGal)

0.070.360.000.000.28

0.280.000.000.120.00

0.560.000.190.000.00

0.000.000.320.060.32

0.440.000.000.000.00

4.230.160.000.000.42

0.000.410.280.020.88

0.000.00

Comp (mGal)

0.310.220.250.280.24

0.420.130.480.270.35

0.290.180.550.170.24

0.150.130.820.570.61

0.730.130.130.180.16

1.560.730.340.280.74

0.170.650.630.430.81

0.180.33


-121.65-140.90-139.76-126.72-138.25

-127.03-146.96-128.29-141.63-134.46

-146.65-144.34-126.99-145.88-144.50

-146.92-147.51-127.02-128.46-126.56

-128.05-146.60-147.15-147.58-148.38

-116.29-126.57-119.89-131.81-126.03

-147.48-126.78-125.72-118.84-124.88

-147.85-154.07

-10-

REFERENCES CITED

Gravity Services Branch, 1970, Gravity base stations, Nevada: St. Louis, Mo., U.S. Department of Defense report, 40 p.

Schaefer, D. H., [in press], Bouguer gravity anomalies, depth to bedrock,and shallow temperature in the Humboldt House geothermal area, Pershing County, Nevada: U.S. Geological Survey Miscellaneous Investigations Map 1-1701.

1983, Gravity survey of Dixie Valley, west-central Nevada! U.S. Geological Survey Open-File Report 82-111, 17 p.

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principal facts for gravity stations in the humboldt · pdf fileprincipal facts for gravity...

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