UBC Theses and Dissertations
Deep resistivity measurements in the Fraser Valley, British Columbia. Samson, John Craig
In the summer of 1967, dipole arrays were used to make deep resistivity soundings in the Fraser Valley of British Columbia. The large dipole moment of the input dipole (270 amp x 37 km) allowed input-to-measuring dipole spacings as great as 100 km. Calculations show that Georgia Strait, which is spanned by the input dipole, should have little effect on layered earth potentials for the dipole to dipole spacings used in this survey. A three-layer model with a resistive second layer (transverse resistance approximately 3000 times that of the upper layer) agrees well with the data. A more complicated four-layer model can be devised by using data from deep wells in the area. Interpretation of well and sounding data indicates that 500 m of conductive ocean and ocean sediments overlie 4-5 km of Tertiary and Cretaceous sedimentary rocks and 2 km of granitic rock. A conducting layer underlying the granitic rock may be the result of water saturation of the rocks at these depths.
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