Q, 10 0-^0
DOE/ID/12079-7
ESL-40
DELINEATION OF AN ELECTRICAL RESISTIVITY ANOMALY,
MALPAIS AREA, BEOWAWE KGRA,
EUREKA AND LANDER COUNTIES, NEVADA
by
Christian Smith
July, 1980
- EARTH SCIENCE LABORATORY DIVISION
UNIVERSITY OF UTAH RESEARCH INSTITUTE
420 Chipeta Way, Suite 120 .
Salt Lake City, Utah 84108
Prepared for the
DEPARTMENT OF ENERGY
DIVISION OF GEOTHERMAL ENERGY
Under Contract No. DE-AC07-80ID12079.
NOTICE
This report was prepared to document work sponsored by the United States
Government.
Neither the United States nor its agent, the United States
Department of Energy, nor any Federal employees, nor any of their contractors,
subcontractors or their employees, makes any warranty, express or implied, or
assumes any legal liability or responsibility for the accuracy, completeness,
or usefulness of any information, apparatus, product or process disclosed, or
represents that its use would not infringe privately owned rights.
NOTICE
Reference to a company or product name does not imply approval or
recommendation of the product by the University of Utah Research Institute or
the U.S. Department of Energy to the exclusion of others that may be suitable.
CONTENTS
Page
ABSTRACT
.............
INTRODUCTION
.'.
...'...•
'. . .
1
2
Geologic Setting
2
Geophysical Setting
5
DIPOLE-DIPOLE RESISTIVITY .
• • • •
10
Description of Surveys
10
Interpretation
12
CONCLUSIONS
19
ACKNOWLEDGEMENTS
.
19 .
REFERENCES
APPENDIX
20
- Dipole-Dipole Numerical Model Output
22
ILLUSTRATIONS
Figure 1
Location Map
3
Figure 2
Generalized Geology
4
Figure 3
Bipole-dipole apparent r e s i s t i v i t y map
6
Figure 4
Three-dimensional i n t e r p r e t a t i v e model, b i p o l e - d i p o l e data
Figure 5
Theoretical b i p o l e - d i p o l e apparent r e s i s t i v i t y map
9
Figure 6
Location map of d i p o l e - d i p o l e p r o f i l e s
n
. . . .
.
8
Figure 7 Interpreted resistivity section and observed apparent
#
resistivity - Line MR 1 . . . . . . . . . . . . . . . . . . .
Figure 8
. 13
Interpreted resistivity section and observed apparent
resistivity - Line MR 2
Figure 9
14
Interpreted resistivity section and observed apparent
resistivity - Line MR 3 . . . .
Figure 10 Interpreted intrinsic resistivity, 3000 foot elevation
#
Figures A1-A3 Numerical model output
......
15
...
16
22
ABSTRACT
The Beowawe Geysers hydrothermal system discharges near the base of an
east-west-trending Basin and Range fault approximately 50 km east of Battle
Mountain, Nevada.
The upthrown block south of The Geysers is called the
Mai pais. . Exposures 2-3 km east of The Geysers reveal a segment of the eastern
boundary of a major north-northwest-trending Miocene graben.
The Geysers are
located along the margin of the graberi near its intersection with the Basin
and Range fault.
A simple numerical model of previously released bipole-dipole resistivity
data shows the margin of the.graben to be anomalously conductive below the
Mai pais.
The conductive area has been delineated with data from a
dipole-dipole resistivity survey run in April, 1980 for this study.
Detailed
numerical models of these data define a 1250 m wide body with resistivities
less than 20 ohm-m that appear to connect The Geysers and the graben boundary.
The minimum depth to the conductor is interpreted to be 375 m; its depth
extent is undetermined.
The electrical data do not resolve whether the anomaly below the Malpais
may be the product of a defunct hydrothermal system or the signature of an
active system.
If thermal gradient data detect an enhanced heat flow anomaly
in the same area, the Malpais may be a viable geothermal exploration target
within the Beowawe KGRA.
INTRODUCTION
.
;
The Beowawe;Geysers, 50 km east of Battle Mountain, Nevada (Figure 1 ) ,
have formed a 2.0 sq km sinter terrace along a short segment of the base of
the Malpais (Figure 2 ) .
Prior to 1979, most geophysical exploration for a
geothermal resource suitable for electric power generation at Beowawe focused
•
on the Whirlwind Valley north of the Malpais.
The southern ends of four
dipole-dipole resistivity lines centered in the Whirlwind Valley cross the
Malpais where they suggest the location of a conductive anomaly (Smith, 1979).
In support of the geothermal program and to understand better the geometry of
the Malpais anomaly, three additional dipole-dipole lines perpendicular to
structural trends were run for this study.
This report presents numerical
models of the new data and suggests that the conductive body below the Malpais
may connect The Geysers to a deep-seated graben-margin fault zone.
This study will be incorporated into a comprehensive case study of the
Beowawe. area (Earth Science Laboratory, in preparation).
Geologic Setting
Figure 2 is a generalized geologic map from Struhsacker (1980) showing
the structural patterns in the Malpais.
The Geysers discharge along a segment
of an east-west.-trending Basin and Range fault; this segment is bounded by the
• North and South Cross-Faults of Osterling (1962).
The major deep-seated
structure in the Malpais is a north-northwest-trending fault set that formed
the eastern boundary of a Miocene graben initially identified by Zoback (1978)
and named the Dunphy Pass fault zone by Struhsacker (1980).
The faults along
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FIGURE 1
LOCATION MAP
BEOWAWE KGRA
the? margin of the graben juxtapose Ordovician Valmy eugeosynclinal
meta-sediments on the east and 1200+ m of Miocene pyroxene dacite flows and
tuffaceous rocks on the west. Silicified fault breccia and country rock at
the intersection of the Dunphy Pass fault zone and the east-west fault at the
base of the Malpais are surrounded by zones of pervasive argilUzation.
These
signs of hydrothermal alteration extend up White Canyon into the Malpais.
Geophysical Setting
The earliest indication of a conductive anomaly in the Malpais was given
by two bipole-dipole apparent r e s i s t i v i t y maps (Wollenberg and others, 1975).
Figure 3 is their map for the transmitter located in the Whirlwind Valley.
The concern that the bipole-dipole method f a i l s to contribute useful
information can be c r i t i c a l l y evaluated through comparisons of these data
and theoretical data from simple models generated by the integral equation
numerical simulator developed by Hohmann (1975).
A circular area of low r e s i s t i v i t y . «30 ohm-m) at The Geysers is flanked
on the west by a finger of higher r e s i s t i v i t y (>50 ohm-m) that wraps around •
the circular low (Figure 3).
of White Canyon.
A companion high-resistivity pattern occurs east
This combination of a local low surrounded by higher values
can be produced by a shallow conductive body (Hohmann and Jiracek, 1979) in a
layered, low-over-high r e s i s t i v i t y earth model (Zohdy, 1978).
Numerical simulations r e s t r i c t i n g the conductive body to the area of The
Geysers f a i l to reproduce the low values observed on the Malpais on the finger
of low r e s i s t i v i t i e s at the mouth of White Canyon in the Whirlwind Valley.
To
iie^ss'
40»35'
40-30'
II6»30'
BEOWAWE NEVADA
BIPOLE-DIPOLE RESISTIVITY
TRANSMITTER I
-X Transmitter Bipole
o Receiver Station
0
Miles
I
ti
Base Map-US6S Dunphy,
Nevada Quadrangle,l957
XBB 743-1632
FIGURE 3
BIPOLE-DIPOLE APPARENT R E S I S T I V I T Y MAP, WHIRLWIND V A L L E Y
TRANSMITTER (FROM WOLLENBERG AND OTHERS, 1 9 7 5 , LAWRENCE
B E R K E L E Y LABORATORY)
6
simulate all the observed' patterns, the conductor must extend southeast of The
Geysers below the Malpais and down White Canyon into the Whirlwind Valley.
Figure 4 is a plan view of the 3D numerical model used to generate the
theoretical data shown in Figure 5.
The conductor has an intrinsic
resistivity of 10 ohm-m and is surrounded by a 60 ohm-m half space.. No
attempt has been made to account for the effects of layering or to duplicate
the amplitudes of the observed patterns or the effect of the topography of the
Malpais (Zoback, 1979).
A comparison between Figures 3 and 5 reveal that the
theoretical data mimic the observed patterns fairly well.
The model of Figure
4 is certainly non-unique but appears to be an adequate simulation o f the
anomaly detected by the bipole-dipole experiment.
The bipole-dipole data suggest that a deep, conductive body associated
with the geothermal resource at The Geysers extends southeast below the
Malpais.
Even though the depth, depth extent, and lateral boundaries of the
anomaly are poorly delimited, the method provides a reconnaissance view that
can be used to site more precise and costly exploration methods.
As noted by
Wollenberg and others (1975), dipole-dipole resistivity or some other
profiling technique is required to obtain a better understanding of the
resistivity distribution below the Malpais.
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Anomaly Resistivity 10 o h m - m
THREE-DIMENSIONAL INTERPRETATION MODEL FOR L A W R E N C E
BERKELEY LABORATORY B I P O L E - D I P O L E DATA.
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DIPOLE-DIPOLE RESISTIVITY
Description of Surveys
Four north-south dipole-dipole profiles with 2000-foot dipoles cross the
Malpais along section lines (Figure 6 ) .
These data were recorded by McPhar
Geophysics in July and November 1974 for Chevron Resources Co. and are part of
the Department of Energy/Division of Geothermal Energy's open-file data
package from Beowawe (Earth Science Laboratory, 1979).
Numerical models of
these data were discussed by Smith (1979) who suggests that a conductive (<15
ohm-m) body may lie below the Malpais.
The data do not extend far enough to .
the south to define the inferred conductor.
To determine the resistivity distribution below-the Malpais, three
additional dipole-dipole profiles were recorded by JCW, Inc. for the Earth
Science Laboratory.in April, 1980 (Figure 6 ) . The profiles cross the Dunphy
Pass fault zone and are approximately perpendicular to it.
These data are
presented here as part of the open-file information sponsored by the
Department of Energy/Division of Geothermal Energy.
The current source for the JCW, Inc. survey was a Scintrex Model IPC-7,
15 kw square-wave transmitter that output an average current of 12.0 -0.5 amps
peak.
Induced voltage was measured to ±0.1 mv with non-polarizing porous
plots, a Scintrex Model IPR-10 digital time-domain IP receiver, and a Scintrex
Model IPR-SA receiver in conjunction with a Hewlett Packard Model 7155B
strip-chart recorder.
Dipole lengths for Lines MR 1 and MR 2 are 2000 feet;
for Line MR 3, 1000 feet.
10
A 2D finite-element algorithm developed by Rijo (1977) and modified by
the Earth Science Laboratory (Killpack and Hohmann, 1979) was used to produce
models of the resi.stivity distribution along the three profiles (Figures
A1-A3).
Figures 7-9 present the interpreted resistivity profiles with the
observed apparent resistivities and Figure 10 presents the interpreted
resistivity distribution at an elevation of 3000 feet.
The results from the
north-south profiles modeled by Smith (1979) are less well constrained but are
included in Figure 10. Agreement among the models is generally good where the
profiles intersect.
Where discrepancies occur, greater weight has been given
to the east-west data which are more nearly perpendicular to the Dunphy Pass
fault zone.
Interpretation
The interpreted resistivity sections. Figures 7-9, contain intrinsic
resistivities that range from 10 to 200 ohm-m.
Lateral contrasts in
resistivity are more pronounced than layering.
The scale for Figures 7 and 8
(2000-ft dipoles) is twice that of Figure 9 (1000-ft dipoles).
To avoid disturbing fledgling eagles in their nests. Line MR 1 was not
completed as a straight line where it crosses the cliff southwest of The
Geysers.
As a result, the westernmost two dipoles produce low resistivities
(10 and 20 ohm-m. Figure A-1) that are partly due to their non-linear
orientation.
The low resistivities computed at the west end of Line MR 1 are
considered to be unreliable representations of the resistivity distribution of
the Whirlwind Valley and are omitted from the interpreted model. Figure 7.
The mesh geometry for all three models attempts to simulate the topography of
12
Dunphy Pass
Fault Zone
8W
10 — I n t r i n s i c
Resistivity
(otim-m)
d a t a r e c o r d e d b y J C W , Inc., A p r i l
Cxi
APPARENT RESISTIVITY
STATION
( 1 0 0 0 ft.)
6W
low
2W
-
OBSERVED
<31
./
/^(ohm-m)
30.5
24.2^^24.8
13.3'
36.9
23.9
36.2
INTERPRETED R E S I S T I V I T Y
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FIGURE 7
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SECTION AND OBSERVED A P P A R E N T
LINE M R l - M A L P A I S AREA
BEOWAWE KGRA
EUREKA AND LANDER COUNTIES, NEVADA
Scale
|'48,000
RESISTIVITY
5000
-3000
-1000
-1000
—1000
• |0V.
elav.
(ft.)
(ft.)
2 0 - Intrinsic R e s i s t i v i t y ( o h m - m j
d a t a r e c o r d e d b y JCW, Inc., A p r i l 1 9 8 O
APPARENT RESISTIVITY 10W
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INTERPRETED R E S I S T I V I T Y
I 29.8
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SECTION AND OBSERVED A P P A R E N T
L I N E MR2 - M A L P A I S AREA
BEOWAWE KGRA
EUREKA AND LANDER COUNTIES, NEVADA
Scale
h4 8,000.
RESISTIVITY
Cross
South
Faults
Nohth
Dunphy Pass
Fault
Zone
5600
5000 —
4000 —
— 2000
• lav.
10 — I n t r i n s i c R e s i s t i v i t y
(ohm-m)
d a t a r e c o r d e d b y JCW, Inc., A p r i l I 9 8 0
m
APPARENT R E S I S T I V I T Y — OBSERVED
STATION
(1000 ft)
5W
1W
3W
h
«0
1g5.0
55.0
^(ohm-m) s o
65.9
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43.8
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43.0
.
22.6
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we.o/^ ' s e . e ^ 42.6
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19.9
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FIGURE 9
+
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INTERPRETED R E S I S T I V I T Y
37V^
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O
SECTION AND OBSERVED A P P A R E N T
LINE MR3 - M A L P A I S AREA
BEOWAWE KGRA
EUREKA AND LANDER COUNTIES, NEVADA
Scale
h24,000
60
RESISTIVITY
the MaipaiSi topographic effects were >found to be as large as ±25%.
Line MR 2 (Figure 8) is the profile furthest from The Geysers and
presumably the least influenced by the hydrothermal system.
resistivity distribution is the least complex.
Its interpreted
Even so, it defines a
deep-seated conductive anomaly west of the mapped location of the Dunphy Pass
fault zone.
This body is the salient feature common to all three sections and
was detected along Line WV 5 and Line WV 6 (Figure 10). The models suggest
that this body has resistivities as low as 10 ohm-m, a maximum east-west width
of 1250 m (4000 ft), and extends to depths of at least 2 km.
Its eastern
boundary is invariably defined by large blocks with resistivities greater than
50 ohm-m within the Dunphy Pass fault zone.
Contrasts in resistivities across
its western boundary are generally less pronounced.,
The conductor is shown to reach the surface along Line MR 1 (Figure 7)
between stations 0 and 2W.
The 30 ohm-m body at the surface between these
stations probably represents the tuff unit that crops out at the head of White
Canyon; most of the bodies with .resistivities of.40 ohm-m or less at the
surface along all three profiles correlate with outcrops of tuffaceous
sediment.
Even though the conductor appears to reach the surface along Line
MR 1, the tuff at the head of White Canyon is too thin to be'the source of the
anomaly at depth.
Other tuff units that do not crop out may produce the
deep-seated low-resistivity zone.
The 1000-ft dipoles of Line MR 3 provide more near-surface detail than
the 2000-ft dipoles of Lines MR l a n d 2 and indicate that the conductor does
not reach the surface (Figure 9 ) . Instead, the 10 ohm-m anomaly occurs at a
17
depth of approximately 375 m (1200 ft), between stations IW and 0, west of
White Canyon and the exposures of tuffaceous sediment.. It underlies a
particularly resistive (120-160 ohm-m) section that may be related to outcrops
of the basalt that is the youngest volcanic unit in the Beowawe area.
The 120
ohm-m body at depth below stations 2.5W and IW may be a local 3D body or it
may reflect a major lithologic break within the volcanic pile.
The Malpais conductor may reflect argil 1ization caused by a defunct
episode of hydrothermal activity or, .possibly, a zone that is still connected
in some way to the active hydrothermaT system at The Geysers.
While it is
unlikely, the anomaly might, also be caused by conductive Ordovician shales at
a shallow depth within the Miocene graben.
These possibilities could be •-
tested with information from 500 m thermal gradient holes.
Below the Whirlwind Valley, the volcanic rocks have resistivities greater
than 50 ohm-m and the underlying Ordovician meta-sediments resistivities less
than 30 ohm-m (Smith, 1979).
Pass fault zone.
A similar contrast is not seen across the Dunphy
Instead, the Ordovician rocks on the east have resistivities
greater than 50 ohm-m.
Several factors could, contribute to the high
resistivities east of the Dunphy Pass fault zone: primary lithologic facies
changes,-lack of saturation by hydrothermal fluids, or secondary hydrothermal
silicification.
The collection and analysis of chip samples from thermal
gradient holes on the Malpais may reveal why the meta-sediments have much
higher resistivities.below; the Malpais than they do below the Whirlwind
Valley.
18
CONCLUSIONS
•
Bipole-dipole data point to a poorly resolved anomaly below the Malpais.
Dipole-dipole data define a conductor 1200 m wide at a depth of 300-400 m with
an undetermined depth extent.
Both the conductive anomaly and The Geysers are confined between the
Northand South Cross-Faults of Osterling (1962) (Figure 10). The anomaly
extends southeast beyond the exposures of the cross-faults, intersects the
Dunphy Pass fault zone within section 22, T31N, R48E, and may possibly
connect The Geysers to the deep-seated faults at the margin of a Miocene
graben. Thermal gradient data may resolve whether this conductor is
associated with a source of heat.
ACKNOWLEDGEMENTS
The bipole-dipole data were supplied by Dr. N. E. Goldstein, Lawrence
Berkeley Laboratories. The dipole-dipole data recording, modeling, and
interpretation were funded by contract DE-AC07-80ID12079 as part of the
Department of Energy/Division of Geothermal Energy's Industry Coupled Program.
Connie Wiscombe typed the manuscript and Connie Pixton drafted the figures.
19
REFERENCES
Earth Science Laboratory, 1979, Chevron Resources Co., data on'Beowawe,
Nevada: Open-file release of March, 1979, Salt Lake City.
Earth Science Laboratory, in preparation. Case study of the Beowawe area, .
north-central Nevada.
Hohmann, G. W., 1975, Three-dimensional induced polarization and electromagnetic modeling: Geophysics, v. 40, p. 309-324.•
Hohmann, G. W., and Jiracek, G. R., 1979, Bipole-dipole interpreation with
three-dimensional models (including a field study of Las Alturas, New
Mexico): Universty of Utah Research Institute, Earth Science Laboratory
Rept. 20, 48 p.
Kill pack, T. J., and, Hohmann, G; W., 1979, Interactive dipole-dipole resistivity and IP modeling of arbitrary two-dimensional structures •(IP2D
user's guide and documentation): University of Utah Research Institute,
Earth Science Laboratory Rept. 15, 107 p.
Osterling, W. A., 1962, Geothermal power potential of northern Nevada: text
of paper presented at the 1962 Pacific Southwest Mineral Industry
Conference of the A.I.M.E.
Rijo, Luiz, 1977, Modeling of electrical and electromagnetic data: Ph.D.
diss.eration, Univ. of Utah', Dept. of Geology and Geophysics,. 242 p.
Smith, Christian, 1979, Interpretation of electrical resistivity and shallow
seismic reflection profiles. Whirlwind Valley and Horse Heaven areas,
Beowawe KGRA, Nevada: Univ. of Utah Research Institute, Earth Science
Laboratory Rept. 25, 43 p.
Struhsacker, E. M., 1980, Geology of the Beowawe geothermal area. Eureka and
Lander Counties, Nevada: Univ. of Utah Research Institute, Earth Science
Laboratory Rept. 37.
Wollenberg, A. A., Asara, F., Bowman, H., McEvilley, T., Morrison, F., and
Witherspoon, P., 1975, Geothermal energy resource assessment: Lawrence
Berkeley Laboratory, Energy and Environment Division, UCID 3762, 92 p.
Zoback, M. ,L. C , 1978, Mid-Miocene rifting in north-central Nevada: A detailed study of late-Cenozoic deformation in the northern Bas.in and
Range: Ph.D. dissertation, Stanford Univ., 247 p. .
Zoback, M. L. C , 1979, A geological and geophysical investigation of the
Beowawe geothermal area, north-central Nevada: Stanford University
Publications, Geological Sciences, v. XVI,.79 p.
20
Zohdy, A. A. R., 1978, Total field resistivity mapping and sounding over
horizontally layered media: Geophysics, v. 43, no. 4, p. 748-766.
21
APPENDIX
Pages 23-25 document all final models. The computed
resistivity values are contoured in the same manner as the
observed data (Figure 7-9) to facilitate comparisono The
resistivities and mode thickness used in the numerical models
are indicated for each model. Unless otherwise indicated,
all node widths are 0.25 dipole lengths.
22
16 W
3X.04«a
.25
.25
55
1i =i Ps
1c
2W
8W
im
i
9
=
1$
~"
a~ "
4W
1m• • 7 6 -
0
m
1
-
kU
7^
c
.5
1
^
3o\aaso
eo
.5
4E
•
-
7^
BE
i
4E
i
3 y /'ypTIo'
^u
40
130
i
1
3
g
JJO'
-Ju
2C
It ?
?< >
3.27
0.50
0.75
1.0
1.25
2.25
•
.5 .
16
1.75
•,'o
3 0
i 1
2.75
4:?
1.0
thlckn«*s >
(a)
lO
3.75
^ - ii i — i — * — ( , 1 — '
0.25
0.22
width
(o)
O.I7
lO - Intrinsic Resistivity (ohm-m) '^^^^
a = 2 0 0 0 ft.
•0.25
flPPflRENT
STATION
(lOOO f t )
6W
10W
-5
I
-4
h
-3
1
»0
RESISTIVITY - COMPUTED
2W
-2
—I
-
1
\
2E
.
0
H
1
\
C^
68
ea^/^ l e r ?
6E
.2
H-
5
1
O
36
^^-\v^
FIGURE A-1
10E
3 . 4
\
1
aeov 92v
<^
«b
COMPUTED MODEL, LINE M R 1 , M A L P A I S A R E A , I T E R A T I O N
8
8W
g5
2XX>94 = S
4 x .1 2v —— ——
6W
s =^
—± £ —
n^
4W
f
—M b
^
0
2W
rf
——
^ ^
mffi s
m =^H>8 0
3x.25(
-
B
zj^d / d S d s b ^ a
m^ e —? m=
n
sc
*K?
^0
0.5
0.5
4E
2E
/PP.PPCE ^
——
£0
^ ^
g^
6E
a
m
BO
==
=- =
<r
^
Bl
0.1
———— ase
0.83
1.08
L33
ff 0
1.83
40
li'C
1
•
233
-^
0.5
A?
li*^
2J83
«c
OS
3.33
1.0
thickness
(a)
10- Intrinsic Resistivity (ohm-m)
a =1000 f t
4^
STATION
(1000 ft.)
nPPRRENT RESISTIVITY - COMPUTED
5W
-5
3W
-4
IW
- 3 - 2 - 1
-I1— \
IE
0
-H
1
1
5E
3E
2
1
3
h-
5
ffO-57.
/'(ohm-m)
^o
^ ^c. i.
FIGURE A - 3
COMPUTED
MODEL. LINE
MR3,
MALPAIS
AREA, ITERATION
6
4.33
d«pth
10)
I2W
lew
H
d fc s "^ 3 fc =
3 3
J56
3@
Sx.OB
^~ ^
~~ — — ^ ;
.16
AX
.25
.25
.25
.25
HZ
8W
!5 E = ^~ a ^
'^ ^~ ^
p
P
1
5 0
BO
8E
= g ;^
— ——
^t^
t^
I2E
"^^
E c;
^
R
1@i M
5C»
"^ ~ ' '
g
,
^
"
I6E
0.1
=?^ 0.4
OS I
i.06
1.31
1.56
JO
•
5 CJ
/([?(b
.50
.50
4E
4W
Z^
^
^^
ffi B £ — a £
3 £ =Sp
—
3 ^ ^ ——— — —^ ^
i>U
J c
-T^
'
SO .
/LKJ
PO
'
2.06
«C
/c>c>
200
2.56
50
3.06
"
I.O
,
•
4.06
thickness
(a)
:
2 0 - Intrinsic Resistivity (ohm-m)'^''^\^
a =2000 ft
ro
en
. nPpflRENT RESISTIVITY - COMPUTED
STATION
(lOOO ft.)
louv
1 ^
6W
-4
2W
-3
<?^
84 O
-2
51
-1
2E
; 0
r
l)^
I*)
(^Qy35 ,
lOE
6E
1
2
26
#-^43
36 V
X
V
X
X
5
—I..
3
22
/^(ohm-m)
74 /
47
o
FIGURE A - 2
COMPUTED MODEL, LINE M R 2 , M A L P A I S
oo
A R E A , ITERATION
5