Geophysical surveys at the Getchell and Preble disseminated gold deposits, Humboldt County, Nevada

Heran, W. D., Smith, B. D.

Geophysical surveys at the Getchell and Preble disseminated gold deposits, Humboldt County, Nevada

Heran, W. D., Smith, B. D. · 1984 · Report

Geophysical surveys at the Getchell and Preble disseminated gold deposits, Humboldt County, Nevada by Heran, W. D., Smith, B. D. (1984). Full text and…

Public-domain full text preserved in the Mountain Man Mining Library. Original source: pubs.usgs.gov.

UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY Geophysical surveys at the Getchell and Preble disseminated gold deposits, Humboldt County, Nevada by William D. Reran and Bruce D. Smith Open File Report 84-795

This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards. Any use of trade names is for descriptive purposes only and does not imply endorsement by the USGS

INTRODUCTION In late June of 1984, the U.S. Geological Survey conducted geophysical studies of two disseminated gold deposits along the eastern flank of the Osgood Mountains in Humboldt County, Nevada (fig. 1). These geophysical investigations were done as part of the U.S. Geological Survey (USGS) Development of Assessment Techniques (DAT) Program to research, assess, and develop exploration techniques and models for mineral deposits. Several geophysical techniques were employed at the Getchell Mine and the Preble prospect. The data from those surveys are presented in this publication with no interpretation in order to effect timely public release. The geophysical methods used were the Very Low Frequency electromagnetic method (VLF), Horizontal loop electromagnetic method (Slingram), total field magnetics, and Spectral Induced Polarization (SIP). The general objectives of the geophysical surveys are: 1) to construct integrated geological and geophysical models which would be useful in mineral assessment and exploration programs, 2) to demonstrate geophysical applications for disseminated gold exploration, and 3) to characterize the petrophysical properties of these ore deposits and their host rocks. GENERAL GEOLOGY The geology of the Osgood Mountains has been described by Hotz and Willden (1964) and the geology of the Getchell mine by Joralemon (1951), and Berger (1975). Little detailed geology has been published on the Preble deposit. The Preble and Getchell deposits are disseminated gold deposits occuring in carbonate-bearing host rocks. The ore bodies are considered to be related to major stratigraphic and structural features of the region. The deposits occur in highly faulted terrane and the orebodies generally spread

'McDermitt GETCHELL N DEPOSIT i w iTVi a w ?o

a MUS Figure 1. Location map showing the location of Humboldt County, and approximate location of the Getchell and Preble deposits.

out laterally from normal faults. The gold deposits of the Getchell mine are in fractured rocks along the Getchell fault zone, predominantly in the Preble formation of Cambrian age. In this area the Getchell fault trends north- northwest. Geophysical Surveys A suite of geophysical data was collected on several lines in the area of the Getchell Mine and the Preble deposit (fig. 2&3). The instrumentation1 used to obtain this data were: A. Electromagnetic Method VLF - Geonics EM16 & EM 16R Horizontal Loop - APEX MaxMin II B. Magnetic Method 1. Protron Magnetometer - Scintrex MP-3 Electrical Method Induced Polarization - Zonge GDP-12 (modified) North-east and east-west trending profiles (G-l and G-2) using EM and magnetics were done in the Getchell mine area, and three in-situ SIP lines were done in the open pit areas of the Getchell mine. The survey in the Getchell mine area consisted of one northeast trending profile approximately 2,500 ft north of the north pit and one northwest-trending profile just south of the middle pit (fig. 2). Two locations were selected for small scale in- situ SIP measurements in "typical" mineralized rock (fig. 2). East-west and northwest-trending profiles (PI, P2, P3, and 777) were done at the Preble deposit using the EM and magnetic methods (fig. 3). On all profiles the of specific brand names does not directly or indirectly constitute endorsement by the USGS, but are used for descriptive purposes only.

0 LINE G-1 Cretaceous Cambrian Kg Cpl Granc Cps Preble Formation. Cpl limestone Cps shale NORTH PIT Figure 2. Generalized geologic map of the Getchell Mine area, showing locations of geophysical lines, (modified from Joralemon,1951) / LiP LINE 1 &1A \1T IP LINE2 SOUTH PIT N feet w f GETCHELL FAULT ZONE

N oH feet H Figure 3. Map showing location of geophysical lines in the Preble deposit area,

numbers corresponding to stations west of station zero (0) are negative and the numbers corresponding to stations east of station zero are positive. GETCHELL Line G-l in the Getchell area north of the north pit was surveyed in using tape and Brunton compass to total 1.1 tons in length. The station interval for line G-l is 12.5 meters. VLF data, consisting of tilt angle (dip) and quadrature readings were taken every 12.5 meters and apparent resistivity and phase angle readings were taken every 25 meters along the entire line. Two different VLF stations were used in the survey, NLK in Seattle, Washington at a frequency of 24.8 Khz, and NAA in Cutler, Maine at a frequency of 24.0 Khz. Horizontal loop electromagnetic (HLEM) readings were done at two different coil spacings of 125 and 200 meters, every 25 meters. Line G-2 just south of the middle pit follows a jeep road trending east- west. Magnetic and VLF measurements were made every 10 meters over this line. Three small scale in-situ spectral induced polarization (SIP) lines were measured in the Getchell mine area (fig. 2). IP line 1 is located just east of the middle pit, directly in the Getchell fault zone, and is 20 meters in length. IP line 1A is perpendicular to IP line 1, and is 8 meters in length (fig. 4). Measurements were taken in a freshly dug prospect pit located in highly sheared and altered Preble Formation (fig. 4). The rock appears to be altered limestone composed almost entirely of clay and black carbonaceous material. Joralemon (1951) refers to this material as "gumbo", consisting of minute subhedral quartz crystals, embedded in a submicroscopic intergrowth of quartz and amorphous carbon. Measurements were taken here to define the

electrical properties of this material. Non-polarizing, lead-lead chloride electrodes were used in a dipole-dipole array with an "a" spacing of two meters. IP line 2 is located along the east wall of the south pit (fig. 2). This line is normal to an area that varies in mineralization along the Getchell fault zone (fig. 5). A 2 meter wide fault surface containing clay and carbonaceous material ("gumbo") is exposed in the pit wall here. The argillite beds have been sheared and tightly folded, and alteration and oxidation is abundant along the entire line. This particular location was chosen because of the variations in structure and mineralization which may be representative of a larger exploration problem. At this location lead electrodes were inserted directly into the outcrop in a dipole-dipole array with the "a" spacing equal to two meters. PREBLE The survey in the Preble area consisted of four profiles generally normal to the structure (fig. 3). All lines have a 12.5 meter station spacing. Line P-l trends east-west and is located directly over mineralized rock. VLF data, consisting of dip and quad readings were taken at each station and apparent resistivity and phase angle data were taken every 25 meters. Horizontal loop (HLEM) readings were taken every 25 meters at 125 meter and 200 meter coil spacings. Magnetic data was collected at each station on all four lines. A Scintrex MP-3 unit was used as a magnetic base station to correct for diurnal variations in both surveys, with the cycle time set at 10 seconds.

PREBLE Fm OXIDIZED ZONE SILICEOUS VEINING IN WALL / ALTERED >ANDESITE K DIKE , IP PROSPECT PIT 20m LINE " t PIT

-t5 40 N10W IP LINE 1 <-ALTERED TO CLAY-> ALONG ENTIRE WALL tvEINS OF REALGAR IN WALL meters Figure 4. Geologic sketch (plan view) of prospect pit showing IP lines 1 and 1A in the bottom of the pit, located east of the middle pit in the Getchell mine area.

FAULT ZONE LOOKING N55E 1cm 1m BLEACHED/ OXIDIZED 4 BLACK THIN BEDDED MASSIVE ARGILLITE CLAY f-ALTERED ARGILLITE-> W/ INTERBEDDED BLACK SHALE Figure 5. Geologic sketch of east wall of the south pit in the Getchell mine area, showing location of IP line 2.

DATA REDUCTION The data reduction and plotting was done on a Hewlett Packard 85 system with programs written in-house (Raab, 1983, 1984). Note that in some cases the plotting programs plot highs or lows that may not be supported by actual data points. The magnetic data is automatically corrected for diurnal variations by internal software in the MP-3 units. A reference value of 54,000 gammas has been subtracted from all the magnetic readings before plotting. The data are plotted as profiles at a scale of 1:3000. VLF and MaxMin data have not been corrected for topographic effects, although the MaxMin data was corrected by subtracting the lowest frequency (222 Hz) from all the other frequencies. Further data reduction such as topographic effects, Fraser filtering etc. will be performed on all data sets. Correlation of all geophysical data and geologic data will be completed in the near future. DATA PRESENTATION The data are presented as profiles plotted at a scale of 1:3000 and as numerical tables in appendices A and 8. Appendix A contains data from the Getchell mine area and appendix B contains data from the Preble deposit area. The order of presentation in each appendix is 1) total field magnetic data, 2) horizontal loop electromagnetic (HLEM) data, 3) very low frequency (VLF) electromagnetic data, 4) spectral induced polarization (SIP) data. The magnetic data are plotted as gammas, after a reference value of 54000 gammas was subtracted from each reading, versus the station location. Tabulated magnetic data are presented after each profile showing the actual magnetic reading. The horizontal loop electromagnetic (HLEM) data are presented as stacked profiles of five frequencies, 222, 444, 888, 1777, and 3555 Hz. The data are

plotted as station location versus percent (%) values of the primary field strength at the receiver; % in-phase (IP), and % out-of-phase (OP). Tabulated HLEM data follows each profile. Two different coil spacings of 125 and 200 meters are each plotted separately. The lowest frequency (222 Hz) has been subtracted from all the other frequencies to correct for topographic effects. The very low frequency (VLF) electromagnetic data are plotted as station location versus apparent resistivity and the phase angle by which E leads H, in degrees. Also plotted is station location versus tilt angle or the vertical in-phase component of the polarization ellipsoid, and the quadrature or the vertical out-of-phase component of the polarization ellipsoid. Tabulated VLF data follows each profile. The two frequencies of 24.8 KHz (Seattle, Wash.) and 24.0 KHz (Guttler, Maine) are plotted separately. Basic Principles of Spectral Induced Polarization The spectral induced polarization method utilizes the characteristics of some rocks to store and release electrical energy through a variety of mechanisms. For a detailed account of these mechanisms the reader is referred to: Madden and Cantwell (1967), Sumner (1976), Washburne (1982) and Olhoeft (1982). The two fundamental parameters measured are amplitude and phase of the received voltage relative to current waveform that is transmitted into the ground. The observed changes in amplitude and phase as a function of frequency result from conduction and polarization processes that produce the IP effect in rocks. These changes in amplitude and phase are commonly plotted on logarithmic scales (Smith et. al., 1983).

Acknowledgements The authors would like to acknowledge the following people: Robert Horton and Gerda Abrams of the U.S. Geological Survey for their help in the data collection and data entry; William Bagby of the U.S. Geological Survey for advice and consultation on the geological parameters; personnel from the Getchell and Pinson mines for their help and cooperation.

References Berger, B. R., 1975, Geology and geochemistry of the Getchell disseminated gold deposit, Humboldt County, Nevada. Hotz, P. E., and Willden, R., 1964, Geology and mineral deposits of the Osgood Mountains quadrangle Humboldt County, Nevada: U.S. Geological Survey Professional Paper 431. Joralemon, P. , 1951, The occurrence of gold at the Getchell mine, Nevada: Economic Geology, v. 46, no. 3, p. 267-310. Madden, T. R., and Cantwell, T., 1967, Induced polarization, A review, in Mining Geophysics, vol. 2, p. 373-400. Olhoeft, G. R., 1982, Electrical properties of rocks and minerals, short course notes, Golden, Colorado, 150 p. Raab, P. , 1983, Slingram data processing and profiling programs for the Hewlett-Packard 85 desktop computer: U.S. Geological Survey Open-File Report 83-461, 45 p. 1984, Magnetic and gravity data processing and profiling programs: U.S. Geological Survey Open-File Report 84- Smith, B. D., Tippens, L. , Flanigan, J. , and Sadek, H. , 1983, Preliminary results of spectral induced polarization measurements, Wadi Bidah district, Kingdom of Saudi Arabia: U.S. Geological Survey Open-File Report OF-03-70. Sumner, J. S., 1976, Principles of Induced Polarization for geophysical exploration: Amsterdam, Elsevier, 177 p. Washburne, J. C., 1982, Parameterization of spectral induced polarization data and laboratory in-situ spectral induced polarization measurements, West Shasta copper-zinc district, Shasta, California: Colorado School of Mines, Unpublished M.S. Thesis No. T259, 270 p.

APPENDIX A Geophysical data in the GETCHELL mine area Data Type Magnetic Data Magnetic Data HLEM Data HLEM Data VLF Data VLF Data VLF Data VLF Data VLF Data VLF Data SIP Data SIP Data SIP Data SIP Data Plot (2 sheets) (2 sheets) (2 sheets) (2 sheets) (2 sheets) (2 sheets) (2 sheets) Line Line Gl Line G2 Line Gl Line Gl Line Gl Line Gl Line Gl Line G Line G2 Line G2 IP Line 1 IP Line 1A IP Line 2 IP Line 2 Description (125 m coil spacing) (200 m coil spacing) (Apparent resistivity and phase angle, 24.8 KHz, Seattle) (Tilt angle (dip) and % Quadrature, 24.8 KHz, Seattle) (Apparent resistivity and phase angle, 24.0 KHz, Guttler, Maine) (Tilt Angle (Dip) and % Quadrature, 24.0 KHz, Guttler, Maine) (Apparent resistivity and Phase angle, 24.8 KHz, Seattle) (Tilt angle (Dip) and % Quadrature, 24.8 KHz, Seattle) Frequency vs. Phase Frequency vs. Phase Frequency vs. Phase Apparent Resistivity Pseudo-Section

MAGNETIC DATA Lines G-l and G-2

GETCHELL LINE 1 06/24/84 MAP SCALE - Is 3000 DISTANCE ( x 1 m

(M r r

GETCHELL 06/24/84 LINE 1 MULTIPLY STATION 1 REFERENCE VALUE 54000 NUMBER OF BASE STATIONS O NUMBER OF STATIONS 81 BASE STATION READINGS N TIME MAG TRAVERSE STATION +0. + 12. +25. +37. +50. +62. +75. +87. + 100. + 112. + 125. + 137. + 150. + 162. + 175. O O READINGS TIME MAG 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: O: 0: 0: 0: 0: O: 0: 0: 0: O: 0: O: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: O: 0: 0: 0: 0: 0: 0: 0: 0: 0: O: 0: o o o o o o o o o o o o 54O67. oo

GETCHELL 06/24/84 LINE - 1 MULTIPLY STATION 1 REFERENCE VALUE 54000 NUMBER OF BASE STATIONS 0 NUMBER OF STATIONS 81 BASE STATION READINGS N TIME MAG TRAVERSE READINGS STATION TIME MAG + 187. +200. +212. +225. +237. +250. +262. +275. +287. +300. +312. +325. +337. +350. +362. +375. +387. +400. +412. +425. +437. +450. +462. +475. +487. +500. +512. +525. +537. +550. +562. +575. +587. +6OO. o O ET, o O O O 0: 0: 0: O: 0: 0: 0: 0: 0: 0: 0: 0: 0: O: 0: 0: 0: 0: O: 0: 0: 0: O: 0: 0: 0: O: 0: O: O: 0: O: O: 0: o o o o o o o o o o oo

MAGNETIC FIELD C9ommo) IN)

BETCHELL 06/27/84 LINE 2 MULTIPLY STATION 1 REFERENCE VALUE 54OOO NUMBER OF BASE STATIONS 0 NUMBER OF STATIONS 76 BASE STATION READINGS N TIME MAG TRAVERSE READINGS STATION TIME MAG -19O +0. + 10. +20. +30. +40. +50. +60. +70. +BO . +90. + 100. + 110. + 120. + 130. + 140. + 150. + 160. + 170. + 1BO. + 190. +200. +210. +220. +230. +240. +250. +260. +270. o o o o A o o o 0: o0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: O0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: o o o o o o o oo oo

BETCHELL 06/27/84 LINE 2 MULTIPLY STATION 1 REFERENCE VALUE 54000 NUMBER OF BASE STATIONS 0 NUMBER OF STATIONS BASE STATION READINGS N TIME MAG TRAVERSE STATION +280. +290. +300. +310. +320. +330. +340. +350. +370. +380. +390. +400. +410. +420. +440. +450. +460. +470. +480. +490. +500. +510. +520. +530. +540. +550. +560. +570. O O o o READINGS TIME MAG 0: 0: O: O: 0: 0: O: O: O: 0: 0: 0: O: O: 0: 0: 0: 0: 0: 0: 0: 0: 0: O: 0: 0: O: 0: o b oo

HLEM DATA Line G-l

PERCENT CD & a & D 3 , ill 111 ii ii ii i ITTI mi niimiiiiiiiiiiiiiiuiiiiiiiiiiii iniiiiiiiiiiiimiiiiiiiiiiiiiiiii iiiiiimiiiiiiiimiiiiiiiiiiiiiii

0Si 0S Zzz

B BBS Z 30Vd

CORRECTED SLINGRAM DATA GETCHELL SLINGRAM 125M/400FT LINE Gl 6/26/84 COIL SPACING 125M MULTIPLY STATION 1 NUMBER OF FREQUENCIES 5 NUMBER OF STATIONS 33

Frequency

STATION ! i i t i i i i i i i -412.5! -387.5! -362.5! -337.5! -312.5! -287.5! -262.5! -212.5! -187.5! -162.5! -137.5! -112.5! -87.5! -62.5! -37.5! -12.5! +12.5! +37.5! +65.5! +87.5! +112.5! +137.5! +162.5! +187.5! +212.5! +237.5! +262.5! +287.5! +312.5! +337.5! +362.5! IP *TjL. . T i ' . jL.wJ . 1 "T i . -IB. 0! 0! 0! 0 ! 0! 0! 0 ! 0! 0! 0! 0! 0! 0! 0! 0! 0 ! 0 ! 0! 0 ! 0 ! 0! 0! 5! 0! 0! 0! 0! 0! 5! 5! 0 ! 5! OP ! i i i i i i -1.0! -1.5! -1.0! -1.0! +0 . 0 ! +0.0! +0. 0 ! + 1.0! -14.0! -5.0! -4. 0! -5.0! -14.0! +55.0! +8.5! +3.5! +2.5! +3.5! +3.5! +3.5! +4.0! +3 . 0 ! +2. 5 ! +4.0! +4.5! +2.0! -5.5! -7.5! -7.5! -1.5! +4.0! IP ! i i i i i i i +2. 0 ! +0. 0 ! +0 . 0 ! + 1 . 0 ! -1.0! +3. 0! +2.0! +4.5! +2. 0 ! -6.0! -1.0! +0. 0 ! -2.0! -6.0! +35 . 0 ! + 1 0 . 0 ! +9. 0 ! +4.0! +3. 0 ! +9 . 0 ! +4.0! +3. 0 ! +5. 0 ! +2.5! +7.0! +6.0! +4.0! +3.5! + 1.5! +4.0! +8.0! OP ! i i i i i i i + 1.5! + 1.0! + 1.0! + 1 . 0 ! +3. 0 ! +3. 0 ! +4 . 0 ! +4.0! +4.0! -26.0! -6.0! -3 . 0 ! -5.0! -19.0! +99.0! +16.0! +7.5! +6.0! +7.0! +7.5! +7.0! +7.5! +5.5! +4.5! +8.0! +9.5! +4.0! -8 . 0 ! -11.5! -11.5! -2.0! +6.0! IP ! i i i i i i i +2.0! +2.0! +0. 0 ! + 1 . 0 ! + 1 . 0 ! +6.0! +4.0! +8. 0 ! +7. 0 ! -2 1.0! -1.0! -3.0! -17.0! +163.0! +26.5! +18.0! +11.5! +11.5! +18.0! +11.5! +13.5! +13.0! +10.5! +17.0! +16.0! +11.0! +9.5! +2.0! 2. 0 ! +10.0! +19.5! OF +4. +3. +3. +3. +5. +6. +8. +7. +8. T-T

vJ . + 1 50 . + 19. +8. +7. + 10. +8. + 11. + 12. +7. +5. + 10. + 12. + 1. ox. + . 0! 0! 0! 0! 5! 0! 0! 5! 0! 0! 0! 0! 0! 0! 0! 0! 0! 0! 0! 0! 0! 5! 0! 0! 0! 0! 5! 5! 0! 0! 0! 0! 5! IP + 10. +6. +4. +6. +6. + 13. + 10. + 12. + 12. + 1.

+ 163. +47. +29. +20. +21. +29. +22. +24. +23. +21. +31 . +29. +20. + 11. +6. +27. 0! 0! 0! 0! 0! 0 ! 0! 0! 0! 0 ! 0 ! 0 ! 0! 0! 0 ! 0! 5! 0 ! 0! 5! 5! 0! 0 ! 5! 0! 0! 0! O! 0! 5! 5! 0! 5! OP ! i i i i i i i +7.0! +4. 0 ! +4 . 0 ! +4.0! +9.0! +9.0! +14.0' +11.0! + 1 0 . 0 ! -42.0! -12.0! -9.0! -10.0! -30 . 0 ! +79.0! +10.0! + 1.0! + 1.0! +8.0! + 1.0! +10.0! +11.0! + 1.0! -3.0! +3.5! +4.0! -21.0! -29.0! -40.0! -44.0! -42.0! -40.0! -33.0! ! IP ' +18.0! +16.0! +13.0! +20 . 0 ! +21.5! +25.0! +29. 0 ! +28. 0 ! +27.0! -64.0' -6-0! + 1.0' -2 - 0 ! -50. 0 ! +163.0! +56.0! +33.. 0 ! +26.5! +38.0! +33.0! +39. 0 ! +41.0! +34. O! +28.5! +42.0! +40. 0 ! +12. 0 ! -10.0! -36.0! -46.5! -47.5' -30 . 0 ! -4.5! t OP ! i i i i i i i +9. 0! +3.0! + 1.0! +10. 0 ! +10.0! +19.0! +14.0! +7.5! -36.0! -19.0! -18.0! -18.0! -22.0! -68.0! -32.0! -27.0! -25. 0 ! -4 . 0 ! -27.0! -4.0! -4.0! -3O . 0 ! -36 . 0 ! -29.0! -32. 0 ! -55.0! -59.0! -56.0! -58.0! -55.0! -65.0! -75.0!

GETCHELL LINE 1 HLEM CORRECTED -222H* COIL SPACING 200. IP - SOLID LINE AND 00 OP - DASHED LINE AND MAP SCALE - It 3800 -: DISTANCE x 1 )

PERCENT CD OUT-PHASE (M t u oo CN

CORRECTED SLINGRAM DATA GETCHELL SLINGRAM 200M/600FT LINE Gl COIL SPACING 200M MULTIPLY STATION 1 NUMBER OF FREQUENCIES 5 NUMBER OF STATIONS 6/26/84 # # #

#

Frequency

STATION ! t -40O. O ! -375 . 0 ! -350 . 0 ! -325.0! -300. 0! -275.0! -250.0! -225.0! -200. 0 ! -175.0! -150.0! I .£. J . U : - 1 00 . 0 ! -75.0! -50.0! -25.0! +0.0! +25.0! +50.0! +75.0! +100.0! +125.0! +150.0! +175.0! +200.0! +225.0! +250.0! +275.0! +300. 0 ! +325. 0 ! IP t TT x~O _T7 0 ! 0 ! 0 ! 0 ' 0! 0! 0! 0! 0 ! 0 ! 0! 0 ! 0 ! 0! 5! 0! 0! 0! 0! 0! 0! 0! 0! 0! 0! 0! 0! 0 ! 0! 0! OP + 1. +2. +3. +3. +2. +3. cr vJ -'

_tr V.J . +75. + 18. +9. +4. +5. +6. +6. +7. +9. +2. + 1. 1 5! 5! 5! 0 ! 5! 0 ! 0 ! 0! 0 ! 5! 5! 0 ! 0! 5! 0 ! Of 0! 0! 0! 0! 0! 0! 0! 0! 0 ! 0! 0! 0! 0! 5! IP t +2. +2. +4. +4. +2. +4. ? +0. +3. +2. +0. +0 . +64. +20. + 13. +9. + 11. + 13. + 12. + 12. + 15. + 11. +7. +5. +0. / 0! 0 ! 0! 0! 0! 0! 0! 0! 0! 0! 0! 0! 0! 0! 5! 5! 0! 0 ! 0! 0! 0! 5! 0! 0! 0! 0! 0! 0! 0! 0! OP !

+3.5! +6.0! +7 . 0 ! +7. 0 ! +6.0! +6. 0 ! -18.0! -6.0! -3. 0 ! -3. 0 ! -5.5! -6.5! -7.0! -32.0! +100.0! +23.0! +13.0! +7.0! +7.5! +8.0! +9.0! +11.0! +14.0! +25.0! -3.5! -10.0! -15.0! -25.0! -27.0! -24 . 0 ! IP +6. +7. +9. + 10. +9. + 12. +0. +4. +3. +0. +0. T + 153. +48. +30. +21. +22. +26. +27. +28. +34. +20. + 14. +3. 0! 0! 0! 0! 0! 0! 0! 0! 0! 0 ! 0! 0! 0! 0! 5! 0! 5! 5! 0! 0! 0! 5! 5! 0! 0! 0! 0! 0! 0! 0! OP ! t +5 . 0 ! +10. O ! +13.0! +13.0! +9. 0 ! +7.5! -30.0! -9.0! -6.5! -7.5! -10.0! -11.5! -11.5! -35.0! +95.0! +19.0! +7 . 0 ! -2. 0! +0. 0 ! +2 . 0 ! +3.5! +4.0! +8.0! -12.0! -25.0! -31.0! -37.0! -43. O! -43.0! -40.0! IP + 15. + 19. +21. +26. +26. +5. +2. + 153. +63. +36. +22 . +26. +30. +33. +36. +30 . + 13. t 0! 0! 0 ! 0 ! 0 ! 0 ! 0 ! 0 ! 0! 0! 0! 0 ! 0! 0! 5! 0! 5! 5! 0! 5! 0! 0! 5! 0! 0! 0! 0! 0! 0! O! OP ! t t +3.5! +11.5! +15.0! +14.0! +7.5! -35.0! -16.0! -15.0! -16.0! -19.5! -26.0! -18.0! -16.0! -60. 0! -25.0! -19.0! -30. 0 ! -25.0! -27 . 0 ! -27 . O ! -28.0! -30.0! -50.0! -54.0! -52.0! -50.0! -51.0! -47.0! -50.0! IP +31. +39 . +39. +47. +36. +30. +3. m + 153. +32. + 16.

ry, + 2. +7. + 11. +5. + 18. 0! 0 ! 0 ! 0 ! 0 ! 0! 0 ! 0 ! 0 ! 0! 0 ! 0 ! 0 ! 0 ! 5! 0! 0 ! 0! 0 ! 0! 0 ! 0! 0! 0 ! 0! 0! 0! 0! 0 ! 0 ! OP ! -12.0! +2.0! +4 . 0 ! +4 . 0 ! -4 . 0 ! -30.0! -30 . 0 ! -31.0! -37.0! -38.0! 40. o ! -45.0! -37 . 0 ! -150.0! -75.0! -56.0! -57.0! -57.0! -64 . 0 ! -62. 0! -70 . 0 ! -77.0! -75.0! -65.0! -52.0! -37.0! -32.0! -27. 0! -35.0!

VLF DATA Lines G-l and G-2

GETCHELL VLF (24.0) LINE-G1 6-24-84 APP RESISTIVITY - SOLID LINE AND 00 - PHASE - DASHED LINE AND MAP SCALE - h 3000 a

P LUa: o a DISTANCE ( x 1 m )

Phase (Degrees) N. /

Cm ¥

ca ca ca ca CO ca ca in ca ca ca ca O) ca ca OJ

GETCHELL RES&PHASE 24 LINE Gl 6/24/84 MULTIPLY STATION 1 NUMBER OF STATIONS 46 STATION RES PHASE 4. .4 wJ -7"=; o / wJ w +0. 0 +25.0 +50 . 0 +75.0 + 1 00 . 0 +125.0 + 1 50 . 0 +175.0 +200 . 0 +225.0 +250.0 +275.0 +300. 0 +325.0 +350.0 +375.0 +400.0 +425.0 +450.0 +475.0 +500.0 +525.0 +550. 0 + 1 GO . 0 +140. 0 +90. 0 +140. 0 +160. 0 +150. 0 +170.0 +180.0 +550. 0 +650.0 +250 . 0 +200. 0 +200 . 0 + 1 00 . 0 +70. 0 +65. 0 +50. 0 + 10.0 +25.0 +40. 0 +50.0 +30 . 0 +70.0 +90. 0 +70.0 +70. 0 +60 . 0 +50.0 +50.0 +60. 0 +40 . 0 +50. 0 +30.0 +25.0 +20. 0 +20. 0 +20.0 +20.0 + 10.0 +30 . 0 +30.0 +30. 0 +35.0 +25.0 +30. 0 +40 . 0

TILT ANGLE (DEGREES) a H- CO m

H-*

ca (A) j o S aaruvaavnoz

BETCHELL DIP?<QUAD 24 LINE Gl 6/24/84 MULTIPLY STATION 1 NUMBER OF STATIONS 85 STATION TILT '/.QUAD

+0.0 + 12.5 +25.0 +37.5 +50.0 +62.5 +75.0 +87.5 +100.0 +112.5 +125.0 +137.5 +0.0 +3 . 0 +2. 0 +0. 0 +2.0 +0. 0 + 11. 0 +20. 0 +20. 0 +24 . 0 +23. 0 + 15.0 +8. 0 + 1.0 + 15.0 + 19.0 +5.0 +4 . 0 +5.0 +4.0 +8.0 +5.0 +3.0 +0.0 +0.0 +5.0 -B.O -B.O -B.O 0 . O 0 . O -B.O -B.O

ETCHELL DIP&QUAD 24 LINE Gl b/24/84 MULTIPLY STATION DUMBER OF STATIONS 85 STATION TILT '/.QUAD +150.0 +162.5 +175.0 +187.5 +200. 0 +212.5 +225.0 +237.5 +250.0 +262.5 +275.0 +287.5 +300.0 +312.5 +325.0 +337.5 +350.0 +362.5 +375.0 +387.5 +400. 0 +412.5 +425.0 +437.5 +450. O +462.5 +475.0 +487.5 +500. O +512.5 +525.0 +537.5 +550.0 +0. 0 +7.0 +9. 0 +8. 0 +5.0 +4 . 0 +9. 0 + 10.0 +8.0 +8. 0 +8. 0 + 10. 0 + 15.0 + 15.0 + 10.0 + 1 0 . 0 +5.0 +5. 0 + 1.0 + 1 . 0 +0. 0 + 1 . 0 +0. 0 +2.0 +3. 0 +4.0 ' +6 . 0 +2. 0 +0. 0 - 1 0 . 0 2 . o

Log Apparent Resistivity (Ohm-M)

h-

CsJ LU PHASE (DEGREES) CD c\j

GETCHELL RES&PHASE 24.8 LINE G-l 6/24/84 MULTIPLY STATION 1 NUMBER OF STATIONS 46 STATION RES PHASE OO"7 tr. .tj / a wJ

+O. 0 +25.0 +50.0 +75.0 + 1 00 . 0 +125.0 +150. 0 +175. 0 +200. 0 +225. 0 +250. 0 +275.0 +300. 0 +325. 0 +350.0 +375.0 +400.0 +425.0 +450.0 +475.0 +500.0 +525.0 +550 . 0 +95.0 +100.0 +90. 0 +100. 0 +140. 0 +180. 0 +180.0 +160. 0 +550.0 +800. 0 +350.0 +400. 0 +250. 0 +90. 0 +70.0 +50 . 0 +50 . 0 + 15.0 +50. 0 +35 . 0 +50. 0 +40. 0 +90. 0 +100. 0 +60. 0 +75.0 +65.0 +55. 0 +55. 0 +30. 0 +45. 0 +50. 0 +40. 0 + 15.0 + 15. 0 + 1 0 . 0 +20.0 + 15.0 +20. 0 +30 . 0 +40. 0 +30. 0 +40. 0 +50 . 0 +55. 0 +60. 0 34. O 34 u 0 ,. 0 35 . O

GETCHELL VLF (24.8) DIP&QUAD LINE=G1 6-24-84 TILT ANGLE SOLID LINE AND - QUADRATURE DASHED LINE AND (+) HAP SCALE 1:3000 in CM en LU LU a: o LU a LU in CMi DISTANCE ( x 1 m )

GETCHELL DIP&QUAD 24.8 LINE G-l 6/24/S4 MULTIPLY STATION 1 NUMBER OF STATIONS 84 STATION TILT 7.QUAD TT7

3OO. 0 r? r?t? A -1B7.5 -5O.O +O.O + 12.5 +25.0 +37.5 +50.0 +62.5 +75.0 +87. 5 +100.0 +112.5 +125.0 +150.0 +162.5 +175.0 -20.O -10.O +3.0 +4.0 + 1.0 +0.0 -B.O o.o O.O

BETCHELL DIP?<QUAD 24.8 LINE ' 6/24/84 MULTIPLY STATION 1 NUMBER OF STATIONS 84 G-l STATION TILT /.QUAD +187.5 +200. 0 +225.0 +237.5 +250.0 +262.5 +275.0 +287.5 +300. 0 +312.5 +325.0 +337.5 +350.0 +362.5 +375.0 +387.5 +400. 0 +412.5 +425.0 +437.5 +450.0 +462.5 +475.0 +487.5 +500.0 +512.5 +525.0 +537.5 +550.0 + 1.0 - 1 0 . 0 +0. 0 + 1.0 +0.0 +0.0 +2.0

XQUADRATURE § CM LU (J> a. in CT) CJ

GETCHELL VLF (24.8) RES&PHASE LINE-G2 6-27-84 APR RESISTIVITY - SOLID LINE AND - PHASE - DASHED LINE AND MAP SCALE 1: 3000 TJ m o m o TO m m to DISTANCE ( x 1 m )

GETCHELL RES&PHASE 24.8 LINE G-2 6/27/84 MULTIPLY STATION 1 NUMBER OF STATIONS 25 STATION RES PHASE -1OO. +0. +2O . +40. +60. +80. + 1 OO . + 1 2.0 . + 140. + 150. + 160. + 180. +200. +220. +240. +260. +280. +300. +320. +340. +360. +380 +400 . o o o o o o o o o + 150. +240. + 1 00 . +90. +45. +60. +50. +30. +30. +20. + 1 0 . +20. + 10. +25. +80. + 1 50 u + 130. + 160. +50. +20 . +20. + 10. + 10. + 15. + 15. o o o o o (") o o Q Q cr'-i 34., o o o o n o o f") n C) o o

GETCHELL YLF (24.8) DIP&QUAD LINE-G2 6-27-84 TILT ANGLE SOLID LINE AND - ZQUADRATURE DASHED LINE AND CO HAP SCALE - 1:3000 in CM LU LUa: o LU O LU CD z. in CMi o o ,0

m DISTANCE ( x 1 m )

GETCHELL DIP&QUAD 24.8 LINE 6-2 6/27/84 MULTIPLY STATION 1 NUMBER OF STATIONS 45 STATION TILT /.QUAD +0.0 + 1 0 . 0 +20.0 +30. 0 +40. 0 +50.0 +60 . 0 +70.0 +80 . 0 +90.0 + 1 00 . 0 +110.0 + 1 20 . 0 +130. 0 +140.0 +150. 0 +160. 0 +170.0 + 1 80 . 0 . +190.0 +200. 0 +210.0 +220. 0 +230 . 0 +240. 0 +250 . 0 +260.0 +270.0 +280. 0 +290. 0 +300.0 +3 1 0 . 0 +320.0 +330.0 +340.0 +350.0 +360.0 +370.0 +380.0 +390.0 +400.0 + 10.0 +5.0 +2 . 0 +2. 0 +5. 0 + 10.0 + 10.0 + 12.0 +8. 0 +5.0 + 1.0 +0.0 +0 . 0 +4. 0 + 10.0 + 10.0 + 1 1 . O +5.0 +3.0 +4 . 0 +0. 0 +2.0 +5.0 + 15.0 +45. 0 +40.0 +30.0

SIP DATA IP LINES 1, 1A and 2

FREQUENCY (Hz)

too. fl Ul Xo. 10H ! FREQUENCY (Hz)

9_. 353Se

ion

0e TO

Uj 2 Co

FREQUENCY (Hz)

IP LINE 2 meters Ln

30, clay/gumbo zone4 APPARENT RESISTIVITY PSEUDO-SECTION VALUES IN ohm-meters as2 meter DIPOLE-DIPOLE ARRAY

APPENDIX B Geophysical data in the PREBLE deposit area Data Type Magnetic Data Magnetic Data Magnetic Data Magnetic Data HLEM Data HLEM Data VLF Data VLF Data VLF Data VLF Data Plot (2 sheets) Line Line PI Line P2 Line P3 Line 777 Line Pi Line PI Line Pi Line PI Line PI Line PI Description (125 m coil spacing) (200 m coil spacing) (Apparent resistivity and phase angle, 24.8 KHz, Seattle) (Tilt angle (Dip) and % Quadrature, 24.8 KHz, Seattle) (Apparent resistivity and phase angle, 24.0 KHz, Guttler, Maine) (Tilt angle (Dip) and % Quadrature, 24.0 KHz, Guttler, Maine)

MAGNETIC DATA Lines PI, P2, P3 and 777

PREBLE LINE 1 06/23/84 HAP SCALE - 1:3000 CM 0E O S a o CM DISTANCE ( x 1 m )

PRtBLE 00/23/84 LINE 1 MULTIPLY STATION 1 REFEREMCE VALUE 0 NUMBER OF BASE STATIONS 0 NUMBER OF STATIONS BASE STATION READINGS N TIME MAG TRAVERSE STATION +0. + 12. +25. +37. +50. +62. +75. +87. + 100. + 112. + 125. + 137. + 150. + 162. + 175. + 187. +200. +212. +225. +237. +250. +262. READINGS TIME MAG 10: 10: 10: 10: 10: 10: 10: 10: 10: 10: 10: 10: 10: 10: 10: 10: 10: 10: 10: 10: 10: 10: 10: 10: 10: 9: 9: 9: 9: 9: 9: 11: 11: 11: 11: 11: 11: 11: 11: 11: 11: 11: 11: 11: 11: 11: 11: 11: 11: 11: 11: 11: 11:

a

en MAGNETIC FIELD (gamma.) m f\9

PREBBLE 06/23/34 LINE 2 MULTIPLY STATION REFERENCE VALUE 000000 NUMBER OF BASE STATIONS 0 NUMBER OF STATIONS BASE STATION READINGS N TIME MAG TRAVERSE STATION +0. + 12. +25. +37. +50. +62. +75. +87. + 100. + 112. + 125. + 137. + 150. + 162. + 175. + 187. +200. +212. +225. +237. +250. +262. +275. +287. +300. READINGS TIME MAG 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: 0: o 54O02.

MAGNETIC FIELD (gamma.) o m I (A) I I

PREBLE 06/23/84 LINE 3 MULTIPLY STATION 1 REFERENCE VALUE 54000 NUMBER OF BASE STATIONS o NUMBER OF STATIONS 50 BASE STATION READINGS N TIME MAG TRAVERSE STATION / r-l +0. + 12. +25. +37. +50. +62. +75. +87. + 100. + 112. + 125. + 137. + 150. + 162. + 175. + 187. +200. +212. +225. +237. +250. +262. +275. +287. +300. +312. +325. +337. +350. +362. +375. +387. +400. +412. +425. +437. +450. +462. +475. +487. +500. +512. +525. O O O READINGS TIME MAG : : :

;

: : mm m m m m j

: :

m m m m m £

:

: : m : : ; ; : ; : : ; : :

4S

PREBLE LINE 777 06/23/84 MAP SCALE Is 3000 ca CM O£ NX ro DISTANCE t x 1 m)

PREBLE 06/23/84 LINE 777 MULTIPLY STATION 1 REFERENCE VALUE 54000 NUMBER OF BASE STATIONS 0 NUMBER OF STATIONS 36 BASE STATION READINGS N TIME MAG TRAVERSE STATION +0. + 12. +25. +37. +50. +62. +75. +87. + 100. + 112. + 125. + 137. + 150. + 162. + 175. + 187. +200. +212. +225. +237. C) READINGS TIME MAG 10: 10: 10: 10: 10: 10: 10: 10: 10: 10: 10: 10: 10: 1 0 : 10: 10: 10: 10: 10: 10: 1O: 11: 11: 11: 11: 11: 11: 11: 11: 11: 11: 11: 11: 11: 11: 11: IB UO

HLEM DATA Line PI

IP - 40 r LINE 1 HLEN CORRECTED -222 Hz COIL SPACING 125m SOLID LINE AND OP - DASHED LINE AND MAP SCALE - h 30O5 3555 Hz 222 Hz DISTANCE ( x 1 )

PERCENT CD QUTHPHASE CM / f

v£> v£>

CORRECTED SL INGRAM DATA PREBLE LINE 1 COIL SPACING 125m LINE 1 COIL SPACING 125m MULTIPLY STATION 1 NUMBER OF FREQUENCIES 5 NUMBER OF STATIONS 06/25/84 20 # # # # #

Frequency

#

t STATION ! -237.5! -212.5! -187.5! -162.5! -137.5! -87.5! -62.5! -37.5! -12.5! +12.5! +37.5! +62.5! +87.5! +112.5! +112.5! +137.5! +162.5! +187.5! +212.5! +237.5! IP 1 o . J. o .

+2. 0 ! 0 ! 0 ! 5! 0 ! 0 ! 0 ! 0 ! 0 ! 0 ! 0! 0! 0! 0! 0! 0 ! 0 ! 0! 0 ! OP +0. +3. +2- +2. +2. +3. +2. + 1. +0. +2. +2. +2. + 1. +2. +2. ! 0! Oi 5! 5! 5! 0! 0! 0 ! 0 ! 5! 0! 0 ! 0! 0! 0! 5! 0! 0 ! 0! 0! IP + 1. + 1. + 1. +2. +2. +2. +2. +3. +4. +3. +5. +4. +3. +2. +3. +4. +3. +3. +3. +3. 0 ! 0! 5! 5! 0 ! 0! 5! 0! 0 ! 0 ! 0! 0! 0! 0! 0 ! 0! 0! 0 ! 5! 0! OP ! + 1 . 0 ! + 1.5! + 1.0! +3. 0 ! +5. 0 ! +4.0! +4.0! +4.0! +4.0! +2.5! +0. 0 f +2.5! + 1.5! -1.5! +0.0! +2. 0 ! + 1.5! IP + 3 . +3 . +4. +5. +4. +6. +6. +7. +8. +7. +7. +7. +6. +5. +5. +6. +5. +5. +7. +5. t 5! 0 ! 5! 0 ! 0 ! 0 ! 5! 0 ! 5! 0! 0 ! 0! 0 ! 0 ! 5! 5! 0 ! 5! 0! 0! OP ! + 1.0! -2.5! + 1.0! +2. 0! +3.5! +9.0! +5.5! +4 . 0 ! +4.0! +5.0! + 1.0! +3.5! +3 S ' -2 . 0 ! -2.0! -6 . 0 ! -4 . 0 ! -1.5! -1.5! IP t +4. +3. +6. +7. +6. +8. + 12. + 12. + 12. + 10. + 10. +8. +6. +7. +7. +6. +4. +5. +8. +7.

5! 5! 5' 5! 0 ! 0! 5! 5! 0 ! 0 ! 0 ! 0! 0! 0! 0! 5! 5! 0! 0! 0 ! OP +0. -7 + 1. +2. + 12. +5. +2. +2. +6. +2. 0 ! 0 ! 5! 0! 0! 5! 5! 5! 0! 5! 5! 0! 0! 0 ! 5! 5! 0! 5! 0! 0 ! IP +8 +5. + 1 3. . + 14. +8. + 15. +23. +20. + 18. + 16. + 19., + 13. +4. + 13. +8. +6. +2. +9. +9.

0 ! o : 5! 0! O i O! 5! 0 ' 0 ! 5! 5! 5! 0 ! OP ! -4 . 0 ! -16.5! - 1 0 . 0 ! -5.0! -10.0! -2. 0! +16.5! +4.5! -5.0! -2.5! +6 . 0 ! -14.0! -32 . 0 ! -1.5! -25.0! -25.0! -35.0! -32.0! -26 . 0 ! -3 1.0!

PREBLE LINE 1 HLEM CORRECTED -222 Hz COIL SPACING 200m IP SOLID LINE AND OP - DASHED LINE AND MAP SCALE - h3000 DISTANCE C x 1 m )

CORRECTED SLINGRAM DATA PREBLE LINE 1 HLEM 600"/200m LINE PI COIL SPACING 200m MULTIPLY STATION 1 NUMBER OF FREQUENCIES 5 NUMBER OF STATIONS 17

Jt-

Frequency

STATION +0. +25. +50. +75. + 1 00 . + 125. + 150. + 175. +200. 0! 0! 0! 0! 0! 0! 0! 0! 0 ! 0 ! 0! 0! 0! O 1 O! 0! 0 ! IP t 0! 0! 0! 0! 0 ! 0! 0! 0 ! 0! 0! 0! 0! 0 ! O 1 5! 0! 0! OP III! + . +0. +2. + 1. +0. +5. +0 . + 1. 4 5! 0 ! 5! 5! 0! 0 ' 0 ! 5! 5! 5! 0! 5! 5! 5! 5! 0 ! 0 ! IP + 1. +3. +4. +3. +4. +5. +6. +3. +0. +0. + 1. +0. + + 1. + 1. + . 0 ! 0! 0! 0! O 1 0! 0! 0! 0! 0 ! 0! 0! 0! 5! 5! 5! 5! OP +0. +4. +2. + 1. + 1. +0. +3. +0. -7 _-j 0! 5' 0! 5! 0! 0! 0 ! 5! 0! 0 ! 0! 0! 5! 0! 0! 0! 0! IP +3. +6. + 10. +9. +5. +7. +8. +8. +2. ! -j

r-T, t 0! 0 ! 5! 0 ! 0 ! 0! 0 ! 0 ! 0 ! 0! 0 ! 0! 0 ! 0! 5! 0! 0 ! OP +3. + . +4. cr . 0! 0 ! 5! 5! 0 ! 5! 5! 0! 5! 5! 0! 5! 0! 0! 0 ! 0! 5! IP +5. +4. + 14. + 11. +7. +8. +9. + 10. + 1. +0 . t 0! 0 ! 0! 0! 0! 0! 0! 0 ! 0! 0! 0! 0! 0! 0! 5! 0! 0! OP

-I cr i ' . +3. 0 ! 0 ! 5' 5! 5! 5! 0! 5 ! 5! 5! 5! 0! 5! 0! 0! 0! 0 ! IP +2. + 18. + 11. +5. +9. +9. + 19. +6. +0.

-1 T JL ' . t t 0 ! 0 ! 5! 5! 0! 0 ! 0 ! 0 ! 0! 0! 0 ! 0! 0 ! 0 ! 5! 0 ! 0 ! OP t t -IS. -IS. 0 ! 0! 0! 0 ! 0 ! 0 ! 0 ! 2 ' 0! 0! 0 ! 0! 0! 0! 0! 0! 0!

VLF DATA Line PI

PREBLE 1 VLF (24.8 SEATTLE) R&P LINE - 1 APR RESISTIVITY - SOLID LINE AND 00 - PHASE - DASHED LINE AND MAP SCALE - h3000 o C/) en LU o: UJ CK

a. CD o ui ui UI "O en m m C/) 0) UI -3m -2m DISTANCE ( x 1 m )

PREBLE 1 VLF (24.8 SEATTLE) R&P 6-21-84 MULTIPLY STATION 1 NUMBER OF STATIONS 49 LINE 1 STATION RES PHASE +0. +25. +37. +50 . +62. +75. +87. + 100. + 112. + 125. + 137. + 150. + 162. + 175. + 187. +2OO. +212. +225. +237. +250. +262. +275. +287. +300. +1000. +1600. +1250. +450 . +20. + 150. +275. +290. +1800. +500. +35. +45. +75. +60. +45. + 165. + 1 90 . +60. + 1 30 . +55. +500. +90. +20. +260. + 10. +85. +20. + 105. +50. +230. +35. +90. +65. +45. +25. +35. +40. +45. +35. +40. +25. +35. +75. +40. +95. +85. +205. + 120. +75. o o o o o o o o o o o o o o o o o o o o

PREBLE VLF (24.8) DIP&QUAD LINE - PI TILT ANGLE - SOLID LINE AND - QUADRATURE - DASHED LINE AND (+) MAP SCALE - 1,3000 LU UJa: CD UJ UJ CD in CM 350* DISTANCE ( x 1 m )

PREBLE VLF (24.8) DIP&QUAD LINE PI 6-21-84 MULTIPLY STATION 1 NUMBER OF STATIONS 50 STATION TILT '/.QUAD

-ii I ji. . - / . +25. +37. +62. +75. +87. + 100. + 112. + 1 '? l=i

J. Ji- W + 137. + 150. + 162. + 175. + 187. +200. +212. +225. +237. +250. +262. +275. +287. +300. +0. +4. + 14. +27. + 10.

Oz.. ' -19. +2.

*"tZ.

! T j +2. + 12. +5. + 16. + 14. + 19. + 11. +5. +3. +3. +8. +3. + 13. + 15. +3. Q +4. +3. + 13. + 16. + 18. + 17. + 14.

+3. +6. o o o o o o o o 8

j. j. T r? o -7 O jL. . o o o o o o o o o o o o o o o

PREBLE VLF (24.0) RES&PHASE APP RESISTIVITY - SOLID LINE AND LINE - PI - PHASE DASHED LINE AND 10 MAP SCALE h 3000 m CD 5Om m DISTANCE ( x 1 m )

PREBLE VLF (24.0) RES&PHASE LINE 6-22-84 MULTIPLY STATION 1 NUMBER OF STATIONS 48 PI STATION RES PHASE

cr

cr - 1 50 . 0 -S7.5 + 0. 0 + 12.5 +25.0 +37.5 +50.0 +62.5 +75 . 0 +87.5 +100. 0 +112.5 +125.0 +137.5 +150.0 +162.5 +175.0 +187.5 +200.0 +212.5 +237.5 +250.0 +262.5 +275.0 +287.5 +300.0 +800. 0 +800. 0 +800. 0 +30. 0 +80. 0 +750. 0 +225. 0 +5000. 0 +225. 0 +55 . 0 +250.0 +95.0 +40. 0 +40. 0 +240. 0 +650. 0 +130. 0 +350. 0 +800. 0 +80. 0 +135.0 +2400. 0 +400. 0 +220. 0 +30. 0 +35. 0 +75.0 +30.0 +210.0 +50. 0 +75 . 0 +110. 0 +75. 0 +20. 0 +35.0 +40. 0 +100.0 +90. 0 +85.0 +70.0 +55.0 +85.0 +110. 0 +145. 0 + 1 80 . 0 +90.0 +180.0 5O. 0 30 . C) 45.O

TILT ANGLE (DEGREES) a i CO n rn en Si II en i en en Si en Si en Si tn ss~ o o "o r- , o m a) ca 2 z ca 5 m S ffl o m o

O) A £20

PREBLE VLF DIP&QUAD (24.0) MAIN 6-23-84 MULTIPLY STATION 1 NUMBER OF STATIONS 48 LINE PI STATION TILT "/.QUAD

+ 12. +25. +37. +50. +62. +75. +87. + 100. + 112. + 125. + 137. + 150. + 162. + 175. + 187. +200. +212. +225. +237. +250. +262. +275. +287. +300. + 14. +25. +33. + 10. +4.

To

1 i jL. . O1 jl. 1 . +5. + 11. + 12. +6. +2. o (") o o o o o o D cr ~?t . vJ . r

C- Mi. -) n er

%J . -j o T;

o o o o o