210 A. M. Alekseev et al. 



seismological survey had shown an upfold in the Mesozoic deposits (Krasno- 

 Bakcharskaia structure). 



In view of the lack of a sufficient number of electrical resistance probes 

 over this territory in the process of the geological interpretation of the 

 observations on telluric current it was necessary to deal only with information 

 on the depths of the current of Paleozoic rocks in the region of Kolpashevo 

 (from drilling data) and in the region of Shegarskoe (from the data of vertical 

 electrical probing). On the basis of these data and using the above formula, 

 a schematic map was drawn for the thickness of friable deposits, lying on the 



Observation points 

 17 36 37 



Fig. 10. Graph of average intensities of the field of teUuric currents along the Tomsk- 

 Bakchar profile (the vertical scale is logarithmic). 



pre-Jurassic foundation (Fig. 11). Despite the rough diagrammatic construc- 

 tions occasioned by sparse network of observations, and the absence of data 

 on the parameters of the cross-section, this map shows how pre-Jurassic 

 rocks dip towards the central regions of the western Siberian Lowlands. 

 To the south of Kolpashevo, there is a zone of upfolded pre-Jurassic rocks, 

 which are of interest for further study. 



In 1956 in the Western part of the Lowlands the experimental work of 

 the VNII Geofizika was continued in order to decide on the applicability of 

 the telluric current method for solving regional and survey problems in the 

 zones of development of volcano -sedimentary deposits of the second structural 

 level, and also in the selling of the Berezovka gas deposits. Within the 

 limits of the Tobol'sk and Vagai-Ishimsk tectonic zones, the party together 

 with the department Zapsibneftegeofizika (led by Yu. S. Kopelev) carried 

 out a large scale structural survey of the Zavodoukovsk area and also a route 

 survey along the profile Zavodoukovsk-Vyatkino-Vikulovo. On the Bere- 

 zovka area studies were made in the region of the group of Berezovka upfolds 

 and along a 280 km regional route along the river Severnaya Sos'va. 



