Lomonosov Moscow State University Faculty of geology Department of Geophysics Arutyunyan D Lygin I Kuznetsov K Sokolova T Shirokova T Shklyaruk A Email David2097mailru ID: 1021449
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1. The latest 3D density model of the Barents Sea crustLomonosov Moscow State UniversityFaculty of geology, Department of GeophysicsArutyunyan D.Lygin I.Kuznetsov K.Sokolova T.Shirokova T.Shklyaruk A.E-mail: David-20.97@mail.ru
2. Introduction2To study the density features of the structure of the earth's crust in the Barents Sea, the following a priori materials were used:anomalies of the gravity field in the Bouguer reduction with an intermediate layer density of 2.67 g/cm3 (World Gravity Model, detail 2´) [Bonvalot, S., 2012];bottom and land topography (IBCAO model, detail 1´) [Jakobsson et al., 2012];topography of the sedimentary cover base (model according to the National Oceanic and Atmospheric Administration data (NOAA SedThick v2.0 model, detail 30´) [Whittaker et al., 2013];relief of the Moho boundary (GEMMA model, detail 5 ') [Negretti et al., 2012].1234
3. Modeling. Step 1Gravity field correction for the three-dimensional influence of the Moho boundary (according to the GEMMA model)3Gravity field correction for the three-dimensional influence of the Moho boundary (according to the GEMMA model). The excess density at the Moho picked by minimizing the standard (root-mean-square) deviation of the gravity effect from GEMMA Moho boundary and Bouguer anomalies. So, the regional density jump at the Moho border is 0.4 g/cm3.Fig. 3 Anomalies of the gravity field in the Bouguer reduction, reduced for the effect of the Moho boundary at an excess density of 0.4 g / cm3Fig. 1 Excess density at the Moho boundary: 1) <0.4 g / cm3; 2) ~ 0.4 g / cm3; 3) > 0.4 g / cm3Fig. 2 Gravitational effect of the Moho boundary
4. Modeling. Step 24Compilation of 3D original model of the base of the sedimentary cover on predictive algorithms of neural networks. The neural network was trained on several reference areas located in different parts of Barents sea using a number of potential fields transformations and the bottom of the sedimentary cover from model SedThick 2.0 Dependence of density changes by depth in the sedimentary cover and the consolidated part of the earth's crustFig. 4 Generalized dependence of density changes by depth in the sedimentary cover and the consolidated part of the earth's crustFig. 5 Anomalies of the gravity field in the Bouguer reduction, reduced for the effect of the Moho boundary and the bottom of the sedimentary cover
5. Modeling. Step 35The finally stripped gravity field is used to create density model above and below the base of the sedimentary cover. Frequency filtering on Poisson wavelets [Kuznetsov et al., 2020] had been used for the final separation of the gravitational field into its components. The inverse task was solved by using specialized volumetric regularization [Chepigo, 2020].Fig. 6 Distribution of excess densities in the upper part of the earth's crust in the consolidated crust (basement)Fig. 7 Distribution of excess densities in the upper part of the earth's crust in a sedimentary cover
6. Conclusion6Based on the collected geological and geophysical data, an analysis of the petrophysical characteristics of the Barents Sea rocks was carried out. Regional concept of density variation with depth was proposed. The three-dimensional density model of the Barents Sea region was created.Within the framework of the obtained 3D density model, new ideas about the structure of the region were obtained:the density heterogeneity of the Barents Sea basement has been proven: the lowest density values are confined to the eastern part of the water area and can be associated with an ancient rift stretching along Novaya Zemlya and its northeastern part, extending into the Kara Sea between Novaya Zemlya and the Franz Josef Land. The density boundary between the plates of the Pechora and Barents seas has been established;the sedimentary cover of the eastern part of the Barents Sea is weakly contrasting in density. The western part of the Barents Sea, the Pechora Sea, the coastal part to the west of Novaya Zemlya (Admiralteyskoye Uplift) are saturated with local density anomalies of different signs (zones of intensive density variation).
7. References7Chepigo L.S. GravInv3D [3D density modeling software]. Patent RF, no. 2020615095, 2020. https://en.gravinv.ru/Bonvalot, S., Balmino, G., Briais, A., M. Kuhn, Peyrefitte, A., Vales N., Biancale, R., Gabalda G., Reinquin, F., Sarrailh M., 2012. World Gravity Map. Commission for the Geological Map of the World. Eds. BGI-CGMW-CNES-IRD, Paris.Kuznetsov K.M. and Bulychev A.A. GravMagSpectrum3D [Program for spectral analysis of potential fields]. Patent RF, no. 2020619135, 2020.Negretti, M., M. Reguzzoni, and D. Sampietro (2012), A web processing service for GOCE data exploitation, in First International GOCE Solid Earth Workshop, Enschede, The Netherlands.Whittaker, Joanne, Alexey Goncharov, Simon Williams, R. Dietmar Müller, German Leitchenkov (2013) Global sediment thickness dataset updated for the Australian-Antarctic Southern Ocean, Geochemistry, Geophysics, Geosystems. doi: 10.1002/ggge.20181.Jakobsson, M., L. A. Mayer, B. Coakley, et al., The International Bathymetric Chart of the Arctic Ocean (IBCAO) Version 3.0, Geophysical Research Letters, doi: 10.1029/2012GL052219.