Мурманская миля. 2016, № 3.

EXPLORATIONS F ig .3 . Summ a ry s e c tio n a long th e line o f reg io n a l tie . Р и с .3 . С водный ге оф и зи ч е с ки й р а зр е з по проф илю р е гионал ьной у вя з ки . 14 naissance stage, then during 2006-2009 the works were con ­ tinued on a regional stage in the northern Barents Sea area, the Pinega area, and also in the Franz Victoria area (F ig .1 ). Later, during 2010-2013 in the period of activation of geo­ logical prospecting works, some additional operations were con­ ducted on the shelf that allowed studying the Trubyatchinsky and Prednovozemelsky blocks in more detail (F ig .2 ). In addition to the available seism ic profile volume, a region­ al connecting seism ic line with length of 750 LKM was com ­ pleted. The RV Geolog Dmitriy Nal- ivkin carried out CMP reflection seismic surveys using the Sercel Seal 648-channel digital seismic streamer with active section length of 8 , 1 0 0 m, record length of 15 sec., shotpoint spacing of 37.5 m. Gravity measurements were performed with the use of the Chekan-AM dual-system gyro- stabilized gravimeter. Mag­ netometer measurements were taken by differential procedure on 100-m base of two SeaSpy marine automated proton mag­ netometers, at the same time, sea bottom echo sounding was performed. The achieved seis­ mic shooting density (total vol­ ume of 31,589.95 LKM) allowed making a quantitative assess­ ment of the resource potential by D 2 category. The obta ined to ta l se t of geophysica l data in te rm s of time, depth and ve lo c ity se is ­ m ic sections, data of gravity and magne tic surveys allowed to perform an integ ra ted geo ­ log ical in te rp re ta tion intended to ge t more validated assess­ ment o f hydroca rbon potentia l in the northern Barents Sea area. By results of the section simulation basing on grav­ ity, hydromagnetic and seism ic data set, there were outlined and characterized the follow ing geological layers: upper mantle, “ granu lite-basic” (lower crust), “ granite -m e tam orphic” (upper crust), terrigenous-carbonate, Perm ian-Triassic terrigenous and Jurassic-C retaceous te rrig ­ enous deposits. The bottom of the Earth crust - Moho boundary (M) - is at depths of 34 - 40 km. The consolidated crust thickness varies from 18-22 km under the northern Barents Sea basin to 32-37 km on its sides. A sign ifi­ cant rise of Moho boundary is accompanied by increase in the sedimentary cover thickness (F ig .3 ). Eight seismic sequences were recognized in the sedi­ mentary cover: Lower - Middle Paleozoic (Pre-Upper Devonian), Upper Devonian - Early Carbon­ iferous, Middle Carboniferous - Lower Permian, Lower - Upper Permian, Triassic (consisting of all the three prelim inary detected sections), Jurassic, Lower- and Upper Cretaceous ones (Fig. 3). The seism ic sequence bounda­ ries are reflecting horizons VI (the bottom of the sedimentary cover); III 2 (D 3 f); IIv(C1); Ia(C 3 -P1); A(P 3 -T1); Б д -K); Г 2 (К -К 2) and D(KZ) (the surface of the Ceno- zoic regional erosion). All basic sequences of the sedimentary cover in the north­ ern part of the Barents Sea shelf are characterized by maxi­ mum thicknesses w ithin the lim ­ its of the Barents Sea - North Kara Sea megadownwarp. In the north-west and south-east parts of the territory, th ick ­ nesses of these sequences are either much reduced because of some erosion processes o c­ curred in d ifferen t geological times (Triassic, Jurassic and Cretaceous deposits in the Prednovozemelskaya structure zone) or are they are fu lly out of the section due to features of the geological evolution history. For example, within the lim its of the Spitsbergen Anticlise and in the Pineginskaya area, se­ quentially, from the west to the east, deposits of M iddle -, then Upper Triassic, Jurassic, Lower and Upper Cretaceous move out below surface of the Cenozoic erosional truncation. Exceptions are pre-Upper Devonian and Upper Devonian - Carbonifer­ ous seism ic sequences, maxi­ mum thicknesses of that are confined to the Prednovozemel- skaya structure zone. In s tru c tu re plan o f the basement su rface d iffe rs six supe ro rde r e lements - the Franz V icto ria regional step, the A leksandrovskaya regional step, the North Barents Sea and East Barents Sea Syn- eclise, separated by the Al- banovsky-Gorbovsky Thresh ­ old. In northwest area, one recognized an arched up lift of the Severo-Vostochnaya Zem lya (the high o f Bely Is­ land). MURMANSK MILE • 3-2016