204 



A. M. Alekseev et al. 



on the degree of metamorphism of the rocks of this stage and the development 

 in them of layers of lava, the surface of the high-resistance electrical marker 

 horizon may be displaced within the limits of the whole volcano -sedi- 

 mentary succession. 



However, this fact does not prevent the application of electric -prospecting 

 to surveys of elevations in the relief of the bottom of the platform -Mesozoic. 

 The results of electrical well -logging show that volcano -sedimentary strata have 

 a higher resistance, due to which the values of total longitudinal conducti- 

 vity (5), obtained during probing, are mainly determined from the parameters 



.22 1 



22 I 



v. Vakhrushevo 

 D 



6 7 



.13 

 .14 

 V Novotyryshkinc 

 10 II 12 13 14 



Fig. 6. Geoelectrical cross-section along CD profile. 1^ — top surface of the Paleozoic 



rocks from data of layer processing of average curves of equatorial and azimuthal 



probes; 2 — top surface of the Paleozoic rocks from results of transforming average 



curves of equatorial and azimuthal probes into curves of axial probes. 



of the Meso-Cenezoic deposits. The small change in the specific electrical 

 resistance of the rocks of the Meso-Cenezoic over a wide range of territory 

 provides favourable conditions for tracking the relative changes in thickness 

 of the friable Meso-Cenezoic succession by the changes in S. This conclusion is 

 confirmed by the results of observations on areas studied by seismic methods^ 

 Figure 7 gives a graph of S compared with the seismic data on the reflecting 

 horizon in the Lower Cretaceous (Valanginian) deposits. The graph of S 

 differentiates two zones of reduced values, associated with the crests of the 

 Viatkinskaia and Krotovskaia structures, which were surveyed by the method 

 of reflected waves. 



Of interest is the identical behaviour of the graph S and the seismic 

 marker horizon which makes it possible to use the S method with a constant 

 parameter Qi selected from the drilling data of the Vyatkinsk area as one of 

 the methods for the quantitative interpretation. 



