-
U.S. DEPARTMENT OF THE INTERIOR
U.S. GEOLOGICAL SURVEY
Vitrinite reflectance data for the Paleocene Fort Union and
Eocene Wind River Formations, and burial history of a drill hole
located in central Wind River Basin, Wyoming
by
Vito F. Nuccio 1
Open-File Report 94-220
This report is preliminary and has not been reviewed for
conformity with U.S. Geological Survey editorial standards (or with
the North American Stratigraphic Code). Any use of trade, product,
or firm names is for descriptive purposes only and does not imply
endorsement by the U.S. Government.
1 USGS, Denver, CO
-
Vitrinite reflectance data for the Paleocene Fort Union and
Eocene Wind River Formations, and burial history of a drill hole
located in central Wind River Basin, Wyoming
by Vito F. Nuccio
INTRODUCTION
Recent discoveries of oil in the Paleocene Fort Union Formation,
and oil shows in the Eocene Wind River Formation, have sparked an
interest in the burial and thermal history of these units in the
Wind River Basin, Wyoming (fig. 1). The purpose of this report is
to present new vitrinite reflectance data, and burial and thermal
information for these and other units for a recently- drilled well
in the central part of the Wind River Basin. By knowing the burial
and thermal history of an area, one can characterize the petroleum
potential of source rocks present, and develop an intelligent
petroleum exploration strategy.
METHODS
Vitrinite, a maceral derived from woody plant material, is
common in coal and carbonaceous shale. Vitrinite reflectance (Ro)
is a measurement of the proportion of light reflected from a
polished vitrinite grain. It is related to the degree of
metamorphism of the vitrinite grain and can be directly converted
to coal rank. Ro values have been correlated with oil and gas
generation for potential source rocks (Dow, 1977; Waples, 1985).
For example, Waples (1985) stated that oil generation begins over a
range of RO values depending on the type of kerogen; onset of oil
generation ranges from about 0.45 percent Ro to 0.50 percent Ro for
high-sulfur kerogen, to 0.60 percent Ro for type II kerogen, to
0.65 percent Ro for type III kerogen. The end of oil generation
also occurs over a range of RO values, but 1.35 percent RO is
commonly accepted as the value at which oil begins to break down
into shorter chain hydrocarbons. Dow (1977) states that oil
generation by liptinitic-rich (Type I) source rocks occurs between
0.50 and 1.35 percent RQ. Wet gas is generated from mixed (Types I,
II, and III) organic matter and from the breakdown of oil between
Ro values of 0.80 percent and 2.0 percent. Dry gas, or thermogenic
methane, is generated from humic organic matter and from the
breakdown of wet gas between Ro values of about 1.0 percent and 3.0
percent. Biogenic gas can be generated at levels of maturity as low
as those for peat (0.20 percent Ro). For this study, "mature" for
oil occurs at 0.60 percent Ro (see fig. 2).
Eighteen coal samples were collected from cleaned cuttings from
the Paleocene Fort Union and Eocene Wind River Formations (fig. 3)
from the Larry Barnes Petroleum, Inc., Carvner Fed. no. 22-15 well
in sec. 15 - T. 37 N. - R. 94 W. (fig. 1). The samples were
prepared for R0 analysis by crushing, mounting in epoxy on a
microscope slide, planing off when hardened, and polishing. The
mean random Ro (from randomly oriented indigenous vitrinite grains)
was determined using plane-polarized incident white light and a 546
nm monochromatic filter, in immersion oil, on a reflected light
microscope with a nonrotating stage (Bostick, 1979; Bustin, 1986).
Thirty measurements were made for each sample, and a mean Ro value
calculated (see Appendix 1 for individual data sheets).
A burial curve and thermal history model (fig. 4) were
constructed for the well using information from several sources.
The thickness of the Fort Union and Wind River Formations were
measured directly from a geophysical log of the well (see fig. 3).
Ages of the Fort Union Formation members were adapted from Nichols
and Flores (1993). Thicknesses and ages of post lower Eocene,
Oligocene and Miocene strata were estimated using data from Love
(1988), Keefer (1970), and Van Houten (1964). The basin modeling
computer program BasinMod (Platte River Associates) was used for
construction of the burial history, and in modeling the vitrinite
reflectance. For this well, a heat flow of 45 mWm~2 was used. This
agrees with present-day heat flow values for the Wind River Basin
(range from 36 to 48 mWm~2) and also in the range of values that
likely existed as far back as Late Cretaceous (Barker and Crysdale,
1993).
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DISCUSSION
Mean RO values for samples from the well studied range from 0.61
percent (uppermost sample collected, 3240-3300 ft) in the Eocene
Wind River Formation to 0.90 percent (lowermost sample collected,
9050-9060 ft) in the Paleocene lower member of the Fort Union
Formation (fig. 5, Appendix 1). Assuming that 0.60 percent RO
represents the beginning of oil generation, the lower part of the
Wind River River Formation, and the entire Fort Union Formation are
in the oil window. The major Tertiary oil source rock in the Wind
River Basin is the Waltman Shale Member of the Fort Union Formation
(Palacas and others, 1993). Katz and Liro (1993) characterized the
Waltman Shale as containing types II and III kerogen, with total
organic carbon content values as high as 7.0 percent. Based on
these geochemical parameters, and the level of thermal maturity
(0.75 to 0.80 for the Waltman zone; fig. 5) from this study, the
Waltman would have to be considered an excellent source rock, and
the likely source of the oil produced in this well. It is also
probable that some of the coals, as well as carbonaceous shales
that occur throughout the entire well, may have generated some
gas.
Figure 4 illustrates the burial and temperature history of units
in the well. Assuming that the burial reconstruction at the well
site is accurate, a heat flow of 45 mWm~2 was required to match the
modeled maturity with the measured Ro values (fig. 5). Using this
heat flow, the base of the Fort Union (base of the Paleocene) was
buried to around 12,300 ft, and reached temperatures exceeding
250°F at maximum burial 15 Ma. RO values of 0.90 percent
characterize this horizon. The top of the Waltman Shale Member was
buried to 10,200 ft, and achieved a temperature of around 250°F at
maximum burial 15 Ma. As mentioned above, RO values are around 0.75
to 0.80 percent at the Waltman level. The Paleocene-Eocene boundary
was buried to approximately 8,000 ft, and reached temperatures of
nearly 200°F at maximum burial and temperature 15 Ma. RO values
cluster around 0.60 to 0.65 at this stratigraphic horizon.
Based on the information presented in this report, the Waltman
Shale Member of the Fort Union Formation has reached the proper
thermal maturity to be in the oil window. It is more than likely
that the oil produced from the Fort Union reservoirs, as well as
oil shows in the Wind River Formation were sourced from the
Waltman.
-
_-.... ...I.-II
-
MO
LN
TAI
«,>i
NS
"
/»;
MW
M
V-I *:
_£#/ ?
w
, v
- I
GR
AN
ITE
M
OU
NT
AIN
S
FIGU
RE
1--Index map of the W
ind River B
asin, Wyom
ing showing location (large dot) of the
Larry B
arnes Petroleum, Inc., C
arvner Fed. no. 22-15 well, located in
sec. 15 -T. 37 N
. - R. 94W.
-
STAGEPRIMARY PRODUCT
HYDROCARBONS GENERATED
PERCENT Ro
HIrrID
rrHI Q.2HI
LJJ
IMMATURE
MATURE
POST-
MATURE
DRY GAS
OIL
WET GAS-
CON DENSATE
DRY GAS
HIGHER
HYDROCARBONS
0.60
0.75
1.0
1.35
FIGURE 2-Generalized scheme for oil and gas generation as a
function of thermal maturity (expressed as RQ) of source rocks.
-
ECDw
CO
1 03trCD
wCD
CDCO
mid. Mio.- present
CDCCD O_g
CDcCDo oD)
O
CDC CDOO
LU
CDCCD O OCD05
Q_
StratigraphicUnit
or event
uplift and erosion
Split Rock Formation
White River
Formation
Post lower Eocene rocks undivided
Wind River andIndian Meadows
Formationsundifferentiated
c.2 Shotgun
-
2606
4606
seas
80Q
0-
10
00
0
12
00
0-
14606
Eoce-ne-
undl-ff
70 66
564
0
30
Tin
e
= 6
FIGU
RE
4--Burial and tem
perature history of Tertiary units discussed in this report.
-
Fm
4806-
6090-
i0eae
12000-
9.5
Eocene- undi-F-f
T-Fs
T-Fw
T-F1
1 Maturity
= 0
FIGURE 5 Graph showing measured vitrinite reflectance data [(+)
and dashed line], and themodeled maturity line (solid line). A
constant heat flow of 45 mWm~2 was used to match the measured and
modeled lines.
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REFERENCES
Barker, C.E., and Crysdale, B.L., 1993, Burial and temperature
history of gas generation from coaly organic matter in the Late
Cretaceous Mesaverde Formation and associated rocks in the deeper
portions of the Wind River Basin, Wyoming, in Stroock, Betty, and
Andrew, Sam, eds., Jubilee Anniversary field conference: Casper,
Wyoming Geological Association, p. 235-258.
Bostick, N.H., 1979, Microscopic measurements of the level of
catagenesis of solid organic matter in sedimentary rocks to aid in
exploration for petroleum and to determine former burial
temperatures a review, in Scholle, P.A., and Schluger, P.R., eds.,
Aspects of diagenesis: Society of Economic Paleontologists and
Mineralogists, Special Publication Number 26, p. 17-43.
Bustin, R.M., 1986, Organic maturity of Late Cretaceous and
Tertiary coal measures, Canadian Arctic Archipelago: International
Journal of Coal Geology, v. 6, p. 71-106.
Dow, W.G., 1977, Kerogen studies and geological interpretations:
Journal of Geochemical Exploration, v. 7, p. 79-99.
Katz, B.J., and Liro, L.M., 1993, The Waltman Shale Member, Fort
Union Formation, Wind River Basin: A Paleocene clastic lacustrine
source system, in Keefer, W.R., Metzger, W.J., and Godwin, L.H.,
eds., Oil and gas and other resources of the Wind River Basin,
Wyoming: Casper, Wyoming Geological Association Special Symposium,
p. 163-174.
Keefer, W.R., 1970, Structural geology of the Wind River Basin,
Wyoming: U.S. Geological Survey Professional Paper 495-D, 35 p.
Love, J.D., 1988, Geology of the Wind River Basin, Central
Wyoming, in Sloss, L.L. ed.,Sedimentary Cover-North American
Craton: U.S.: The Geological Society of America, Decade of North
American Geology, p. 196-200.
Nichols, D.J., and Flores, R.M., 1993, Palynostratigraphic
correlation of the Fort UnionFormation (Paleocene) in the Wind
River Reservation and Waltman area, Wind River Basin, Wyoming, in
Keefer, W.R., Metzger, W.J., and Godwin, L.H., eds., Oil and gas
and other resources of the Wind River Basin, Wyoming: Casper,
Wyoming Geological Association Special Symposium, p. 175-189.
Palacas, J.G., Flores, R.M., Keighin, C.W., and Anders, D.E.,
1993, Organic geochemical typing of oils in the Wind River Basin,
Wyoming: [abst] American Association of Petroleum Geologists 1993
Annual Convention Program, p. 162.
Van Houten, F.B., 1964, Tertiary geology of the Beaver Rim area,
Fremont and Natrona Counties, Wyoming: U.S. Geological Survey
Bulletin 1164, 99 p.
Waples, D.W., 1985, Geochemistry in petroleum exploration:
Boston, International Human Resources Development Corporation, 232
p.
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APPENDIX 1
Vitrinite reflectance data
Each data sheet represents the mean random vitrinite reflectance
data for the individual coal
samples. The File Name is the project name. The Channel Name is
the name of the analyst, and
Comment 1 is information regarding the quality of the sample.
For each coal sample several
vitrinite grains were measured. These are listed on the data
sheet in the Pi. column, and
correspond to the values in the Meas 1 column. The minimum
reading (Min), maximum reading
(Max), mean value of all readings (Mean), and standard deviation
(StDev) are given. The Mean is
the R0 value for the sample, and is the value plotted in fig.5
and discussed in the text. The
histogram for measurements of the sample are also given.
-
File Name: RFVN Channel Name: Nuccio Description: 3240-3300
Comment 1: Good sample,Comment 2:Comment 3:Comment 4:Comment
5:Comment 6:
Min:Max:Mean:StDev:
Pt. X-Pos Y-Pos
1 23456789
101112131415161718192021222324252627282930
Clean and consistent
Measl Meas2 Ratio Cone
0.540.680.610.04
Z-Pos Measl Meas2 Ratio Cone.
0.64
0.670.620.630.590.640.660.590.640.570.580.610.600.580.580.590.610.640.600.600.590.570.550.590.540.560.680.660.670.54
10
-
F r equencyO 'i:..'
o
T3CD
's
OCD
r-.
o o
o
O
oI I
O
11
-
File Name: RFVN Channel Name: Nuccio Description: 4500-4550
Comment 1: Good sample, Clean and consistentComment 2:Comment
3:Comment 4:Comment 5:Comment 6:
Measl Meas2 Ratio Cone
Min: Max: Mean: StDev:
Pt. X-Pos
123456789
1011121314151617181920212223242526272829303132
0.58 0.76 0.67 0.05
Y-Pos Z-Pos Measl Meas2 Ratio Cone.
0.670.640.610.640.590.580.670.680.650.620.620.670.730.590.690.680.650.690.620.690.710.760.670.710.700.710.610.750.720.740.710.73
12
-
r e Q Li e n c "
:.::."' o o
O
O
r-j
r-j O i ::)
ix; i...i::,.
13
-
File Name: RFVN Channel Name: Nuccio Description: 4650-4680
Comment 1: GoodComment 2:Comment 3:Comment 4:Comment 5:Comment
6:
Min: Max:Mean:StDev:
Pt. X-Pos
123456789
101112131415161718192021222324252627282930
sample, Clean and consistent
Measl Meas2 Ratio Cone
0.61 0.760.670.04
Y-Pos Z-Pos Measl Meas2 Ratio Cone.
0.640.650.640.670.630.660.640.660.680.640.630.650.650.670.760.750.700.730.690.680,670.660.610.710.680.620.630.630.670.65
14
-
FrequencyO
| o r-,] !
o o o o oI I I I.o --- - -----^
CD........
o CD
.......
O
O ...j:.
15
-
File Name: RFVN Channel Name: Nuccio Description: 4860-4870
Comment 1 : GoodComment 2:Comment 3:Comment 4:Comment 5:Comment
6:
Min:Max:Mean:StDev:
Pt. X-Pos
1 23456789
101112131415161718192021222324252627282930
sample, Clean and consistent
Measl Meas2 Ratio Cone
0.590.720.640.03
Y-Pos Z-Pos Measl Meas2 Ratio Cone.
0.68
0.660.680.650.720.640.640.640.630.670.630.640.640.630.620.600.640.600.590.630.660.620.600.620.630.650.640.650.640.61
16
-
FrequencyO
1-...Jo
...i::,.
"D
0) ,.....,
O
i""':
o o
.
0I\J o
\ >
;..,.! :: -]
O
CO
17
-
File Name: RFVN Channel Name: Nuccio Description: 5020-5030
Comment 1: Good sample,Comment 2 :Comment 3:Comment 4:Comment
5:Comment 6:
Min:Max:Mean:StDev:
Pt. X-Pos Y-Pos
1 23456789
101112131415161718192021222324252627282930
Clean and consistent
Measl Meas2 Ratio Cone
0.530.740.660.06
Z-Pos Measl Meas2 Ratio Cone.
0.70
0.740.700.670.650.660.670.630.630.640.590.670.600.600.590.730.740.690.740.690.700.610.610.590.530.560.730.720.730.64
18
-
Frequency O Cn ::::r ot-,j Ki
! o w
KIo o 0
1.4 O
I. .... i
O CD
O
Ki
19
-
File Name: RFVN Channel Name: Nuccio Description: 5320-5340
Comment 1: Good sample, Clean and consistentComment 2:Comment
3:Comment 4:Comment 5:Comment 6:
Measl Meas2 Ratio Cone
Min: Max: Mean: StDev:
Pt. X-Pos
1 23456789
101112131415161718192021222324252627282930
0.57 0.76 0.68 0.05
Y-Pos Z-Pos Measl Meas2 Ratio Cone.
0.60
0,670.670.590.590.570.620.670.660.660.650.720.710.760.730.690.660.680.700.750.680.720.640.680.740.670.680.650.710.72
20
-
! -
!"' i" F i'"j I i P \"\ i'" \i :I i ' ..' \.| -..-I ':.< ! 1
':.' ':'
r-.j
""[j
i' )
\ !/
;' 'i
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Cn
' ...,.'
' ! ''i
21
-
File Name: RFVN Channel Name: Nuccio Description: 5530-5540
Comment 1: Good sample, Clean and consistentComment 2:Comment
3:Comment 4:Comment 5:Comment 6:
Measl Meas2 Ratio Cone,
Min: Max: Mean: StDev:
Pt. X-Pos Y-Pos
1 23456789
101112131415161718192021222324252627282930
0.54 0.67 0.62 0.03
Z-Pos Measl Meas2 Ratio Cone.
0.58
0.570.570.630.640.630.650.660.650.640.540.600.570.590.630.640.630.670.640.650.640.620.600.600.610.610.620.630.610.60
22
-
O
Ci
O
....... o
LJ:::
Cl...
OO
ic-
o !n r\iLI:':;- .1:::
D IJ9fl b 9 J J
-
File Name: RFVN Channel Name: Nuccio Description:
Comment Comment 2: Comment 3 Comment 4: Comment 5 Comment 6
5700-5710Good sample, clean grains large
Measl Meas2 Ratio Cone
Min: Max: Mean: StDev:
Pt. X-Pos Y-Pos
123456789
101112131415161718192021222324252627282930
0.56 0.71 0.63 0.04
Z-Pos Measl Meas2 Ratio Cone.
0.560.580.700.700.640.650.710.640.640.620.670.650.590.580.580.640.640.590.650.630.640.630.640.620.640.560.600.680.570.56
24
-
Frequency O c.: :::r -,.r-j
r-..:;o
o o I
o
TJ .....,,
Oa-
oKla
: i
CO
25
-
File Name: RFVN Channel Name: Nuccio Description: 6060-6070
Comment 1: Good sample,Comment 2:Comment 3:Comment 4:Comment
5:Comment 6:
Min:Max:Mean:StDev:
Pt. X-Pos Y-Pos
1 23456789
101112131415161718192021222324252627282930
Clean and consistent
Measl Meas2 Ratio Cone
0.650.750.710.02
Z-Pos Measl Meas2 Ratio Cone.
0.69
0.750.720.720.700.730.750.730.720.730.700.730.750.700.680.710.720.730.710.740.650.700.710.700.700.690.700.710.730.70
26
-
Fr equency O C-i::r or-J CO
i O
o o
o
O
"i:;;:: o
l/l
TJ
(!) .......
O
27
-
File Name: RFVN Channel Name: Nuccio Description: 7540-7560
Comment 1: Good sample,Comment 2:Comment 3:Comment 4:Comment
5:Comment 6:
Min:Max:Mean:StDev:
Pt. X-Pos Y-Pos
123456789
101112131415161718192021222324252627282930
Clean and consistent
Measl Meas2 Ratio Cone
0.560.780.670.07
Z-Pos Measl Meas2 Ratio Cone.
0.740.740.700.730.720.740.730.720.690.700.580.560.600.640.650.630.650.640.650.630.570.580.570.730.770.780.760.580.610.63
28
-
Frequency
oKi
C' O
IO
o1 I I
1:1 CD
o (1)
liili
29
-
File Name: RFVNChannel Name: NuccioDescription: 7740-7750
Comment 1: Good sample,Comment 2:Comment 3:Comment 4:Comment
5:Comment 6:
Min:Max:Mean:StDev:
Pt. X-Pos Y-Pos
1 23456789
101112131415161718192021222324252627282930
Clean and consistent
Measl Meas2 Ratio Cone
0.720.770.750.01
Z-Pos Measl Meas2 Ratio Cone.
0.76
0.770.750.750.740.720.760.760.770.770.770.760.740.730.750.740.720.750.750.750.740.740.760.750.750.720.750.750.750.72
30
-
Frequency o --J:::r -, !r-j 4----
| OI-...J
TJ
CD
O CD
o o
o
o
o!
r-o o
O
O
31
-
File Name: RFVN Channel Name: Nuccio Description: 7900-7910
Comment 1: Good sample, Clean and consistentComment 2:Comment
3:Comment 4:Comment 5:Comment 6:
Measl Meas2 Ratio Cone
Min: Max: Mean: StDev:
Pt. X-Pos
1 23456789
101112131415161718192021222324252627282930
0.79 0.97 0.90 0.05
Y-Pos Z-Pos Measl Meas2 Ratio Cone.
0.93
0.960.960.930.820.840.820.910.910.940.790.920.950.970.950.950.950.920.960.830.870.870.880.890.850.930.930.890.860.83
32
-
FrequencyO
TJ
Oa-
...,.,
'.'17' 0'!
o
o
O
...L
o
oI\-J
33
-
File Name: RFVN Channel Name: Nuccio Description: 8120-8130
Comment 1: Good sample,Comment 2:Comment 3:Comment 4:Comment
5:Comment 6:
Min: Max:Mean:StDev:
Pt. X-Pos Y-Pos
123456789
101112131415161718192021222324252627282930
Clean and consistent
Measl Meas2 Ratio Cone
0.81 0.970.900.04
Z-Pos Measl Meas2 Ratio Cone.
0.89
0.900.960.950.860.860.870.960.890.960.880.970.910.920.890.860.930.930.920.910.940.950.880.880.810.850.870.890.850.90
34
-
Frequency oK:;
IK!
Tl
CD
n
o o .
o
o
o
o O o
O
o io
35
-
File Name: RFVN Channel Name: Nuccio Description: 8220-8230
Comment 1: GoodComment 2:Comment 3:Comment 4:Comment 5:Comment
6:
Min:Max:Mean:StDev:
Pt. X-Pos
1 23456789
101112131415161718192021222324252627282930
sample, Clean and consistent
Measl Meas2 Ratio Cone
0.730.870.800.04
Y-Pos Z-Pos Measl Meas2 Ratio Cone.
0.76
0.740.800.860.870.840.750.850.780.740.770.830.810.760.730.850.840.850.740.760.770.740.850.830.750.810.780.780.810.81
36
-
Frequency O ai:::r r-or-j I--,)
i o
'""[ICD """';
O CD
o o I
o
a
r\:i o
i
O
SJ'J
O i
O
37
-
File Name: RFVN Channel Name: Nuccio Description: 8580-8590
Comment 1: Good sample,Comment 2:Comment 3:Comment 4:Comment
5:Comment 6:
Min:Max:Mean:StDev:
Pt. X-Pos Y-Pos
1 23456789
101112131415161718192021222324252627282930
Clean and consistent
Measl Meas2 Ratio Cone
0.821.000.890.04
Z-Pos Measl Meas2 Ratio Cone.
0.88
0.890.920.890.900.910.910.870.850.930.890.910.870.890.890.840.860.880.830.891.000.880.940.850.870.820.860.930.940.92
38
-
FrequenceO Oi
Ki OS I C'
l"0 I
-
File Name: RFVN Channel Name: Nuccio Description: 8720-8730
Comment 1 : GoodComment 2:Comment 3:Comment 4:Comment 5:Comment
6:
Min:Max:Mean:StDev:
Pt. X-Pos
1 23456789
101112131415161718192021222324252627282930
sample, Clean and consistent
Measl Meas2 Ratio Cone
0.800.990.890.06
Y-Pos Z-Pos Measl Meas2 Ratio Cone.
0.30
0.800.950.970.970.960.970.940.990.870.960.960.830.850.850.880.890.890.870.870.900.810.860.890.920.910.890.890.840.84
40
-
Frequency
Kio
OB
"'"0
CD........
O
(I)
o o I
o
o
O
I
O{....Io
I I
O
41
-
File Name: RFVN Channel Name: Nuccio Description: 9050-9060
Comment 1: GoodComment 2:Comment 3:Comment 4:Comment 5:Comment
6:
Min: Max:Mean:StDev:
Pt. X-Pos
123456789
101112131415161718192021222324252627282930
sample, Clean and consistent
Measl Meas2 Ratio Cone
0.81 0.940.900.03
Y-Pos Z-Pos Measl Meas2 Ratio Cone.
0.880.930.900.910.880.920.890.930.910.820.920.870.820.810.920.930.920.890.870.890.890.920.920.930.940.940.930.920.910.92
42
-
f r e c| u e n c y
r-o
T3CD
i' ';
CD1
'i. !i ''.U
.....i ^ j! -, '! f T!
'!./]!I"""!
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