Мурманская МИЛЯ. 2018 г. №4.

EXPLORATIONS 28 deposits of dislocated fold basement almost crop out. It is confirmed by high-amplitude positive anomalies of magnetic field which are associated with invasion of a big number of magmatic rock bodies available at shal­ low depths. The basement is overlapped by the cover consisting of the Caledonian, Cim­ merian and Alpine deposits. In addition the Cimmerian sequence is represented by its’ upper horizon (lower Cretaceous) and the Apt-Albian plateau-basalt in the roof. The let­ ter spread northwards to the Podvodnokov basin. They are embedded in the bottom of the Alpine (synoceanic) sequence and can be traced on the seismic lines as ‘acoustic basement’. The Alpine sequence is thinned and reduced by erosion in the arch of the high. Its’ thickness increases towards the north-east to the Podvodnokov basin where it reaches almost full stratigraphic volume. The East Siberian rift system determines the structure of the De Long High southern side. The system of grabens of sub-meridi­ onal extension has been defined. The Vilkitsky trough modifies the side of the De Long high and the eastern slope of the East Siberian rift system. The depths drop of the bottom is from 6.0 to 11.0 km and more. It should be noted that the sedimentary cover in the area of the Vilkitsky trough contact with the east Siberian rift system is rich with the hydrocarbon indirect indicators associated with the fault zones which allows supposing the de­ velopment of stratigraphic traps of hydrocar­ bon in the sedimentary cover along its side. Besides this, there are thick delta sequences developed in the Oligocene to lower-Miocene formation of the Vilkitsky trough. There have been detected the features of probable hydrocarbon accumulation which are typically located on the fault flex­ ural blocks and terraced flanks and asso­ ciated with faults and flexure bends (Fig. 3). Main oil-and-gas prospects seem to be associated with the zones of sequences pinching out and development of delta and flank facies where the formation of strati- graphic and lithological traps of hydrocar­ bon is possible. All over the exploration area there were detected bright spot anomalies associated with the archs of local highs and faults (Fig. 4). The most significant anomaly was record­ ed in the arch of the Demidov saddle. It is 39.5 km long. 20 local anticline highs were mapped. In the eastern part of the area there was local­ ized the Romanov swell sized 130*130 km Fig. 3 O il-and -gas potential scheme. 1 - adjacent parts of deep depocentres. The limits of the Cretaceous and Cainozoic sequences pinching out: 2 - m id-late-M iocene (N 12 -N 13) deposits, 3- Oligocene to early M iocene ^ - N ^ ) deposits, 4 -P aleocen e to Eocene (P ^ ) deposits, 5 -u p p e r Cretaceous deposits (К 2 ), 6 -A p t - Albian deposits (К 1); 7 -isopachytes of sedim entary cover; 8 -profile lines. Рис. 3. Схема перспектив нефтегазоносности. 1 - прибортовые части глубоких депоцентров. Границы выклинивания меловых и кайнозойских ССК: 2 - средне­ позднемиоценовых (N 1 2 -N 13) отложений, 3- олигоцен- раннемиоценовых ^ - N ^ ) отложений, 4 - палеоцен-эоценовы х (P1-2) отложений, 5 - отложений верхнего мела (К2), 6 - отложений апт-альба (К1); 7 - изопахиты осадочного чехла; 8 - линии профилей. (Fig. 5) at which there are three sufficient­ ly large structures delineated, they are the Aleksandrovskaya, Nikolayevskaya and Alek- seevskaya ones. Main features of the sedimentary cover structure were detected, namely: its’ thick­ ness, pinchinh-out zones of certain sequenc­ es and on the contrary their growth within the limits of the prograded shelf. All these give reasons for the positive evaluation of petro­ leum prospects. The data obtained became the basis for updating of the regional qualitative assess­ ment of hydrocarbon resources. In order to evaluate the resources potential there was a standard chosen in the Beaufort Sea within the limits of the Mackenzie delta (paleo-del- ta). Forecast resources along the upper Cre­ taceous to Cainozoic part of the section of the explored part of the East Siberian conti­ nental margin estimated at 0.45 billion TOE. MURMANSK MILE • 4-2018