288 V. I. FoMiNA 



It is obvious from Fig. 5 that when the AB are spacings orientated per- 



pendicular to the plane of contact on the VEP curve for all values of — , 



H 



the true position of the right-hand asymptotic branch can be defined as the 



mean of the right-hand branches of VEP curves with equal . 



d 

 For values of — — > 2, the true position of the right-hand asymptotic 

 H 



branch can be defined by the line running at an angle of 45° from the point 



. d 



of divergence of curves wdth equal — . 



The position of the contact is fixed by the abscissae of the maximum devia- 

 tions of Qj^ in opposed directions. 



When the separations of AB are orientated parallel to the plane of the 



^ d 

 contact for — > 2, the true position of the asymptotic branch running at 

 H 



d 

 an angle of 45° from the point of divergence of curves with equal — is 



H 



depicted on Fig. 11. 



If all the characteristic variations in VEP curves along profiles men- 

 tioned above are used in the interpretation of VEP curves, one can indicate 

 zones in which the horizontal homogeneity is disturbed and the correspond- 

 ing tectonic dislocations and also establish the true position of the asymptotic 

 branch of the VEP curve. An example of the interpretation of VEP curves 

 in one of the regions is given in Fig. 13. 



The VEP profile is disposed transversely to the direction of the anticlinal 

 fold axis. As has been showai above, the position of the non -horizontal bound- 

 aries is determined by the analysis of the distortions in VEP curves. 



Despite the fact that there are two non -horizontal boundaries in the 

 given case, the total influence of which creates a much more complicated 

 picture in the distortions on the VEP curves true values of S were deter- 

 mined by painstaking analysis of all the VEP curves along the profile and 

 the depth at which the reflecting horizon lay was established. These results were 

 subsequently confirmed by drilling (the drilling points are plotted on the 

 profile). 



The abscissae of the maximum deviations of Qj^ from (o^ j^j^ are indic- 

 ated (by arrows) in the upper part of this profile. 



In sectors where the abscissae of ^^ converge wth deviations of different 

 direction one can assume the presence of a non -horizontal contact. It is 

 not difficult in this case to show that the smaller the area of convergence of 



