Resistivity of the California Wash and Astor Pass
description
Transcript of Resistivity of the California Wash and Astor Pass
Resistivity of the California Wash and Astor
Pass
Objectives• The California Wash
• Astor Pass North-South
• Astor Pass East-West
• Astor Pass AP 1, 2
• Conclusions
The California Wash
N
1 10 100100
1000 Resistivity of California Wash
Line 2Line 1Line 3Line 4Line 5
A-Spacing (m)
Apar
ent R
esis
tivity
(Ωm
)
Layer 1 Thickness(m)
Layer 2 Thick
Layer 3 Thick
Layer 4 Thick
Resis1 (Ωm) Resis 2 Resis 3 Resis 4 RMS
line 1 2 1 14inf 600 270 150 700 14.69invert 2.14 0.001 18.38inf 612.47 269.98 166.12 701.29 14.41Line 2 1 5inf - 600 270 338 - 9.22 1.91 0.002inf - 494.28 0.321 330.17 - 7.05Line 3 3.3 10 6inf 850 200 250 300 29.02 3.75 0.99 0.001inf 737.71 36.98 260.25 285.38 21.84Line 4 2 3 7inf 350 200 170 520 7.13 3.77 0.001 2.98inf 340.72 199.67 81.25 451.96 5.53Line 5 1 1.5 4inf 350 650 620 300 15.07 0.831 3.96 0.001inf 321.13 712.64 620.63 294.12 12.79
Results and Interpretations• Lines 1-4 show a decreasing
resistivity both with depth and initial resistivity of soil
• Line 5 lies higher than 1-4 and shows a higher resistivity
• Depth profiles of lines 3 and 5 show inversions from layers 1, 2 and 4
• Lines 1-4 are on a downward slope of a graben which ultimately ended in a wash. Line 5 lies on top of a horst to the west of the graben. This is expected as the graben would probably collect more moisture and have a lower resistivity than the higher lying horst.
1 10 100100
1000 Resistivity of California Wash
Line 2Line 1Line 3Line 4Line 5
A-Spacing (m)
Apar
ent R
esisti
vity
(Ωm
)
East-West
1 10 1001
10
100 Astor Pass 101 Resistivity
101(E-W)101(N-S)"101-A(N-S)"101-C(E-W)
A-Spacing (m)
Apar
ent R
esisti
vity
(Ωm
)
1 10 1001
10
100 Astor Pass 148/160 Resistivity
148(E-W)148(N-S)148-A(N-S)148-C(N-S)160(N-S)
A-Spacing (m)
Apar
ent R
esisti
vity
(Ωm
)
1 10 1001
10
100 Astor Pass 196 Resistivity
196(E-W)196(N-S)196-A(N-S)196-C(N-S)
A-Spacing (m)
Apar
ent R
esisti
vity
(Ωm
)
Resistivity of the California Wash and Astor
Pass
Layer1 Thickness(m) Layer 2 Thic Layer 3Thick Resis1 (Ωm) Resis 2 Resis 3 RMS101 (E-W) 2 18 inf 44 10 3 14invert 1.77 25.55 inf 42.93 10.05 0.001 10.5101 (N-S) 2 7.5 inf 38 10 5 5.99
1.46 6.14 inf 41.95 13.12 5.1 3.55101-A 2.7 inf - 41.95 11 - 9.57
2.77 inf - 42.15 10.73 - 9.45101-C 2.2 inf - 78 4.2 - 12.49
2.06 inf - 79.19 4.3 - 9.77148 (E-W) 3 10 inf 60 15 2.6 15.61
1.69 6.98 inf 59.15 28.83 3.33 11.07148 (N-S) 1.7 7.2 inf 45 29 3 6.86
1.34 7.41 inf 46.35 30.79 2.78 6.46148-A 2.5 5.5 inf 34 32 5 14.31
0.0006282 7.14 inf 0.036 35.02 5.05 8.84148-C 2.4 7 inf 15 55 9.5 10.56
3.11 0.97 inf 14.86 356.04 9.93 8.92196 (E-W) 1.2 5.1 inf 65.4 15 7.2 9.75
0.83 3.66 inf 84.1 20.58 7.69 7.93196 (N-S) 1.6 4 inf 57 12 7.7 9.51
1.98 47.15 inf 53.22 8.71 0.001 8.2196-A 2.9 5 inf 24 9.2 7 4.26
2.24 2.85 inf 24.53 14.24 7.41 3.89196-C 1.2 5.5 inf 85 16 5.5 12.4
1.3 6.63 inf 85.95 13.06 5.42 11.8160 (N-S) 0.5 4.5 inf 4.9 55 4 7.24
1.09 2.57 inf 9.19 90.56 4.67 6.42
Results and Interpretations
• As we go across the fault E-W the resistivity goes up Considerable across the 148/160m section, interpreted To be the fault.
• 101 and 196 m lines show general Q type and have a lower resistivity than the 148/160m lines indicating a build up along the fault of resistive mineralization
• The 148/160m lines are interacting with the tufa, the calcification of the tufa has resulted in a decrease inresistivity in the subsurface below this line
North-South
1 10 1001
10
100 Astor Pass C Resistivity
101-C(E-W)148-C(N-S)196-C(N-S)160(N-S)
A-Spacing (m)
Apar
ent R
esisti
vity
(Ωm
)
1 10 1001
10
100 Astor Pass Resistivity
101(E-W)101(N-S)148(E-W)148(N-S)196(E-W)196(N-S)
A-Spacing (m)
Apar
ent R
esisti
vity
(Ωm
)
1 10 1001
10
100 Astor Pass A Resistivity
"101-A(N-S)"148-A(N-S)196-A(N-S)
A-Spacing (m)
Apar
ent R
esisti
vity
(Ωm
)
Layer1 Thickness(m) Layer 2 Thic Layer 3Thick Resis1 (Ωm) Resis 2 Resis 3 RMS101 (E-W) 2 18 inf 44 10 3 14invert 1.77 25.55 inf 42.93 10.05 0.001 10.5101 (N-S) 2 7.5 inf 38 10 5 5.99
1.46 6.14 inf 41.95 13.12 5.1 3.55101-A 2.7 inf - 41.95 11 - 9.57
2.77 inf - 42.15 10.73 - 9.45101-C 2.2 inf - 78 4.2 - 12.49
2.06 inf - 79.19 4.3 - 9.77148 (E-W) 3 10 inf 60 15 2.6 15.61
1.69 6.98 inf 59.15 28.83 3.33 11.07148 (N-S) 1.7 7.2 inf 45 29 3 6.86
1.34 7.41 inf 46.35 30.79 2.78 6.46148-A 2.5 5.5 inf 34 32 5 14.31
0.0006282 7.14 inf 0.036 35.02 5.05 8.84148-C 2.4 7 inf 15 55 9.5 10.56
3.11 0.97 inf 14.86 356.04 9.93 8.92196 (E-W) 1.2 5.1 inf 65.4 15 7.2 9.75
0.83 3.66 inf 84.1 20.58 7.69 7.93196 (N-S) 1.6 4 inf 57 12 7.7 9.51
1.98 47.15 inf 53.22 8.71 0.001 8.2196-A 2.9 5 inf 24 9.2 7 4.26
2.24 2.85 inf 24.53 14.24 7.41 3.89196-C 1.2 5.5 inf 85 16 5.5 12.4
1.3 6.63 inf 85.95 13.06 5.42 11.8160 (N-S) 0.5 4.5 inf 4.9 55 4 7.24
1.09 2.57 inf 9.19 90.56 4.67 6.42
Results and Interpretations
• Along the E-W sections from North-South the same results are shown as in the East-West sections the148/160m lines show increased resistivity
• Comparing in this direction it is clear the differencebetween the 148/160m lines and the 101m and 196m lines
• Interpreting in a different direction again shows the center 148/160m lines have increased resistivity indicating the presence of the tufa build up in the subsurface
Wells AP 1 & 2
1 10 1001
10
100 Astor Pass AP Resistivity
Well AP1,2(N-S)Well AP3(N-S)
A-Spacing (m)
Apar
ent R
esisti
vity
(Ωm
)
AP 1,2 0.001 4.5inf 5 7 4.5 7.860.0005023 1.67inf 0.004 10.98 4.66 2.86
AP3 0.5 2 9 27 8 22 3.76layer 4 inf 3.7
1.12 0.026 4.62 17.06 0.104 37.72 2.1layer 4 inf 4.79
Layer1 Thickness(m) Layer 2 Thic Layer 3Thick Resis1 (Ωm) Resis 2 Resis 3 RMS
Results and Interpretations
• The position is located on top of packed, non-local sediments as well as having drillwells might have interfered with readings
• Results show a relatively constant resistivitydown past the 10m A spacing
• Resistivities higher than near the tufa at the 101m and 196m
• The data shows little change in in the shallower a spacing depths, this could be artificial due to the location and manipulation due to previous drilling of the immediate area, lower Resistivities at depth but didn’t seem out of place with the 101m and 196m lines
Conclusions• California Wash Shows there is a decrease in resistivity on lines 1-4 then a sudden
change and increase at line 5 which would be expected as line 5 runs along a horst above the graben which would hold more moisture making the resistivity lower. The Remi data shows also that the velocity models would indicate the graben haslower subsurface layers which could act as a channel keeping in moisture which would increase the conductivity in this area.
• Astor Pass shows that there is an anomaly that runs along the 148/160m lines. The data shows an increase in resistivity along this section of Astor Pass, whichwe interpret as being the carbonate build up of the tufa towers in the subsurface.The Remi data also shows the Vs30 velocities decrease along the same lines this indicates the same anomaly along the subsurface roughly along the same 148/160m lines. Leading us to believe that the tufa is acting as the resistor.
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