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Two-dimensional models of seismic P-and S-wave velocity in the crust and upper mantle derived by forward ray-tracing modelling using the SEIS83 package (Červený and Pšenčík 1983) along the BALTIC profile: (a) P-wave velocity models. Thick, black lines represent major velocity discontinuities (interfaces). (b) S-wave velocity models. Those parts of the first order discontinuities that have been constrained by reflected or/and refracted arrivals of S waves are marked by thick lines. (c) Models of V P /V S ratio distribution. Those parts of the first order discontinuities that have been constrained by reflected or refracted arrivals of P or/and S waves are marked by thick lines. Thin lines represent velocity isolines with values in km/s shown in white boxes in (a) and (b) and V P /V S ratios in (c). Position of large-scale crustal blocks is indicated. Arrows show positions of shot points.
Source publication
The paper presents an analysis of the crust and upper mantle structure in the central Fennoscandian shield based on new P- and S-wave 2D velocity models of the BALTIC wide-angle reflection and refraction profiles. Using reprocessing of the old data, new P- and S-wave velocity models and V
P/V
S ratio distribution were developed. Moving from SW to N...
Contexts in source publication
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... refracted and reflected P and S waves were used in 2D ray tracing modelling. Resulting P-and S-wave velocity models and the V P /V S distribu- tion are shown in Fig. 6. Examples of the interpreted phases, synthetic seis- mograms, and the fit between the observed and calculated travel-times are shown in Figs. ...
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... Used approach was to estimate the velocity of the layers above and below the Moho and use the average of these values as the isovelocity line best representing the Moho. For example, a value of ~7.5 km/s was derived using this approach for the southwest portion of the profile, and the velocities calculated in the model derived by ray-tracing Fig. 6) are 6.9 km/s above and 8.2 km/s below the Moho. For the central and northeastern parts of the transect, this approach suggests that the Moho should be approximately interpreted at the 7.9 km/s isoline. The tomographic inversion was only a preliminary assessment, before the main modelling by regular ...
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... observed travel times and the model was successively altered at each iteration step. This procedure was continued until an agree- ment of the order of 0.1-0.2 s was achieved between the observed and mod- el-derived travel times. The derived final 2D P-and S-wave velocity models and the V P /V S distribution along the BALTIC profile are shown in Fig. ...
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... is significant lateral variation of seismic velocities and thickness of the crust along the BALTIC profile. In the P-wave velocity model (Fig. 6), we can distinguish three major crustal layers on the basis of P-wave velocity values and major intracrustal ...
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... ray-tracing technique. For S wave, we used the bandpass filter of 1-6 Hz and reduction velocity 4.62 km/s. P-wave data have been filtered using the band-pass filter of 2-12 Hz and displayed using the reduction velocity of 8.0 km/s. Synthetic seismograms and ray of selected rays of P wave. All examples were calculated for the models presented in Fig. 6. M1, M2 -upper mantle discontinuities; other abbreviations as in Fig. 3c. , the best solution that gives good agreement of calculated and observed travel times and amplitudes of major phases (see Figs. 9-14) was selected. In this model, a sub-Moho(M 1 ) layer with velocities ca. 8.15 km/s was intro- duced in the southwestern part of ...
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... velocity has been observed at first arrivals. This is in a good agreement with the data, as this phase is observed as "secondary" arrivals (see Figs. 8 and 9 and Pn in Fig. 14) on the record sections from SP A and SP B only, at distances of 95-235 km and 135-250 km, respectively. In the bottom of sub-Moho layer, a boundary called M 2 was found (Fig. 6) in an area with velocities ~8.4 km/s (denoted as the HVUM). In the central part of the profile (distances from 255 to 360 km), M 2 became the regular Moho boundary, which separates the HVUM directly from the HVLC. The dome shape of the top of the HVUM was obtained mainly by fitting the calculated travel times to the observed re- ...
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... of the identified P-wave phases were accompanied by the correspond- ing S-wave phases. Travel times of correlated reflected and refracted S waves were used to estimate the S-wave velocity model (Fig. 6), from which the distribution of V P /V S ratio was calculated for the principal layers of the crust and upper mantle (Fig. 6). The geometry of the first-order disconti- nuities in the S-wave velocity model was inherited from the P-wave velocity model (Fig. 6). Documented pieces of the interfaces were identified using the same ...
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... of the identified P-wave phases were accompanied by the correspond- ing S-wave phases. Travel times of correlated reflected and refracted S waves were used to estimate the S-wave velocity model (Fig. 6), from which the distribution of V P /V S ratio was calculated for the principal layers of the crust and upper mantle (Fig. 6). The geometry of the first-order disconti- nuities in the S-wave velocity model was inherited from the P-wave velocity model (Fig. 6). Documented pieces of the interfaces were identified using the same seismogram analysis as used for P ...
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... reflected and refracted S waves were used to estimate the S-wave velocity model (Fig. 6), from which the distribution of V P /V S ratio was calculated for the principal layers of the crust and upper mantle (Fig. 6). The geometry of the first-order disconti- nuities in the S-wave velocity model was inherited from the P-wave velocity model (Fig. 6). Documented pieces of the interfaces were identified using the same seismogram analysis as used for P ...
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... S-wave velocities and V P /V S ratio are ~4.7 km/s and ~1.75 in the up- permost mantle, and ~4.85 km/s and 1.75 in HVUM, respectively. These values are not well constrained because of less clear arrivals of Sn phases on most of record sections, and are marked with "?" on the model (Fig. ...
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... only); and Luosto and Heikkinen (2001), although they dif- fer in some details. The largest difference of the model from the previous ones was found in the upper crust, the structure below WRM, and V P /V S ratio distribution. The new model changes the geometry of boundaries and V P dis- tribution, usually from 0.1 to 0.15 km/s in the upper crust (Fig. 6). As men- tioned in Chapter 5.3.1, few areas with velocities of 5.8-5.9 km/s to a depth of 6 km were modelled. In the central part, instead of a relatively small body with V P = 6.3 km/s, a larger body with variable shape and only slightly high- er velocities than the surrounding layers was used in the model (Fig. 7). Ad- ditionally, a ...
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... stability of the final solution for Pg, PmP, Sg and SmS phases is illu- strated in Fig. 16. The arrival times were calculated for the velocity models with perturbed values of velocity or depth to the reflecting interface. As can be seen in Fig. 16, the arrival times of the Pg phase calculated for the veloci- ty model with velocities perturbed by ±0.2 km/s was much either too late or too early. Figure 16 shows that velocity ...
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... stability of the final solution for Pg, PmP, Sg and SmS phases is illu- strated in Fig. 16. The arrival times were calculated for the velocity models with perturbed values of velocity or depth to the reflecting interface. As can be seen in Fig. 16, the arrival times of the Pg phase calculated for the veloci- ty model with velocities perturbed by ±0.2 km/s was much either too late or too early. Figure 16 shows that velocity in the upper crust can be determined with an accuracy better than ±0.1 km/s. The sensitivity of the arrival times of the PmP to the perturbations of the Moho ...
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... can be seen in Fig. 16, the arrival times of the Pg phase calculated for the veloci- ty model with velocities perturbed by ±0.2 km/s was much either too late or too early. Figure 16 shows that velocity in the upper crust can be determined with an accuracy better than ±0.1 km/s. The sensitivity of the arrival times of the PmP to the perturbations of the Moho depth by ±2 km is shown in the same plot. ...
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... sensitivity of the final model to perturbations of the S-waves veloci- ty in the upper crust was tested for Sg phase using the model with V P /V S val- ues in the upper crust perturbed by ±0.02 (Fig. 16). In the same plot, the arrival times of the SmS phase calculated for the velocity model with V P /V S ratio in the lowermost crustal layer perturbed by ±0.05 are shown. The anal- ysis demonstrates that the uncertainty of S-wave velocity, or rather V P /V S ra- tio, can be estimated as ±0.02 for the upper crust and ±0.05 for the lower ...
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... in the modelling of the POLONAISE'97, CELEBRATION 2000, SUDETES 2003 and POLAR wide-angle reflection and refraction profiles, for which analyses of accuracy were presented by Janik et al. (2002Janik et al. ( , 2009, Grad et al. (2003Grad et al. ( , 2006Grad et al. ( , 2008Grad et al. ( ), and Środa et al. (2006. However, many details in the Fig. 16. Test of resolution of calculated travel times using the SEIS83 ray-tracing technique for SP A. upper diagram -Example of the arrival times of Pg phase (V P ~ 6.3 km/s) with velocity perturbation ±0.2 km/s and the arrival times of the Moho reflections PmP (depth ~36-40 km) together with the perturbation of the Mo- ho depth of ±2 km. ...
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... rozoic and Archaean domains. The Outokumpu area (OA) limits the Eastern Finland complex (EFC) on the southwest. The values of V P , V S and V P /V S in the block are generally same as the corresponding values in the central block. Also, depths of boundaries are same except of the ~5 km uplifts found for boundaries in UC and bottom of HVLC (see, Figs. 6 and 17). The depth to the Moho boundary decreases from 64 km in the southwest to 60 km in the northeast. The profile was not long enough to get clear image of this block. It seems quite sure that the structure changes towards northeast, be- cause substantially different results were obtained for the Russian part of Ka- relian domain, e.g., ...
Citations
... 2.10 приведен пример сейсмограммы, иллюстрирующий записи вертикальными сейсмоприемниками как продольных, так и поперечных волн, обычно регистрируемых при ГСЗ. Это позволило многочисленным исследователям Фенноскандинавского щита, даже несмотря на отсутствие 3-компонентоной регистрации, широко использовать при интерпретации S-волны и помимо построения традиционных скоростных моделей Vp выполнить оценки значений Vp/Vs и коэффициентов Пуассона в земной коре [Pilipenko et al., 1999;Abramovitz et al., 2002;Kuusisto et al., 2006;Kuusisto, 2007;Silvennoinen & Kozlovskaya, 2007;Tiira et al., 2010;Janik, 2010;Stratford & Thybo, 2011a;2011b;и др.]. На рис. ...
... Рис. 2.10. Сейсмограмма, иллюстрирующая записи продольных (Рg, PcP, PмP, Pn, Pov) и поперечных (Sg, SмS) волн вертикальными сейсмоприемниками [Janik, 2010] Рис. 2.11. ...
... 2.12. Скоростные разрезы земной коры и верхней мантии по профилю BALTIC [Janik, 2010] На первом разрезе (рис. 2.11), пересекающем грабен Осло, приводится скоростная модель Vp и распределение значений коэффициента Пуассона в земной коре и верхней мантии до глубины 60-70 км. ...
В книге приведен обзор глубинных исследований земной коры континентов и океанов с использованием продольных и поперечных сейсмических волн. Показаны возможности многоволновой сейсморазведки для повышения
информативности глубинных исследований земной коры за счет использования значений параметра Vp/Vs и коэффициента Пуассона. Приведены результаты многоволновых сейсмических исследований Арктической зоны, северо-востока России и прилегающих акваторий.
The book introduces in deep studies overview of continental and oceanic Earthʼs crust using compression and shear seismic waves. Multiwave seismics opportunities using values of the Vp/Vs and Poissonʼs ratios for geological objectives solutions
are shown. Multiwave seismics studies of the Arctic and North-East regions of Russia and adjacent water areas are presented.
... Synthetic seismograms were calculated for qualitative control over modeled and observed amplitudes. Additionally, the input model was supplemented by the data from partially parallel FIRE3 profile and information from crossing profiles SVEKA81, BALTIC and FENNIA Janik 2010;Kukkonen and Lahtinen 2006). The two-dimensional forward modeling with ray tracing method resulted in P-wave velocity distribution model shown in Fig. 9a. Figure 4 provides general overview of modeling including ray-paths, synthetics and overall fit to experimental data. ...
The Kokkola–Kymi Deep Seismic Sounding profile crosses the Fennoscandian Shield in northwest-southeast (NW–SE) direction from Bothnian belt to Wiborg rapakivi batholith through Central Finland granitoid complex (CFGC). The 490-km refraction seismic line is perpendicular to the orogenic strike in Central Finland and entirely based on data from quarry blasts and road construction sites in years 2012 and 2013. The campaign resulted in 63 usable seismic record sections. The average perpendicular distance between these and the profile was 14 km. Tomographic velocity models were computed with JIVE3D program. The velocity fields of the tomographic models were used as starting points in the ray tracing modelling. Based on collected seismic sections a layer-cake model was prepared with the ray tracing package SEIS83. Along the profile, upper crust has an average thickness of 22 km average, and P-wave velocities (Vp) of 5.9–6.2 km/s near the surface, increasing downward to 6.25–6.40 km/s. The thickness of middle crust is 14 km below CFGC, 20 km in SE and 25 km in NW, but Vp ranges from 6.6 to 6.9 km/s in all parts. Lower crust has Vp values of 7.35–7.4 km/s and lithospheric mantle 8.2–8.25 km/s. Moho depth is 54 km in NW part, 63 km in the middle and 43 km in SW, yet a 55-km long section in the middle does not reveal an obvious Moho reflection. S-wave velocities vary from 3.4 km/s near the surface to 4.85 km/s in upper mantle, consistently with P-wave velocity variations. Results confirm the previously assumed high-velocity lower crust and depression of Moho in central Finland.
... 5.4. The nature of the lower crust, crust-mantle boundary, and velocity-density Moho discontinuity beneath the Karelian Craton and the Svecofennian Accretionary Orogen It has been reliably established that the Precambrian crust of the Fennoscandian Shield, similar to all other continental domains, is characterized by subhorizontal density layering: the high-velocity and highdensity lower crust, variable in thickness and depth, occurs at the base of the Svecofennian Orogen and the adjacent tectonic subdivisions of regional rank as well (Korsman et al., 1999;Bock et al., 2001;Bogdanova et al., 2006;Janik, 2010;Janutyte et al., 2014;Glaznev et al., 2015). This circumstance suggests that interpretation of composition and origin of the lower crust at the base of the Svecofennian Orogen should be comparable with similar characteristics at the base of neighboring domains (Figs. 4F, 6E and 7D). ...
A 3D model of deep crustal structure of the Archaean Karelia Craton and late Palaeoproterozoic Svecofennian Accretionary Orogen including the boundary zone is presented. The model is based on the combination of data from geological mapping and reflection seismic studies, along profiles 1-EU, 4B, FIRE-1-2a-2 and FIRE-3-3a, and uses results of magnetotelluric soundings in southern Finland and northern Karelia. A seismogeological model of the crust and crust-mantle boundary is compared with a model of subhorizontal velocity-density layering of the crust. The TTG-type crust of the Palaeoarchaean and Mesoarchaean microcontinents within the Karelia Craton and the Belomorian Province are separated by gently dipping greenstone belts, at least some of which are palaeosutures. The structure of the crust was determined mainly by Palaeoproterozoic tectonism in the intra-continental settings modified by a strong collisional compression at the end of the Palaeoproterozoic. New insights into structure, origin and evolution of the Svecofennian Orogen are provided. The accretionary complex is characterized by inclined tectonic layering: the tectonic sheets, ~15 km thick, are composed of volcanic–sedimentary rocks, including electro-conductive graphite-bearing sedimentary rocks, and electro-resistive granitoids, which plunge monotonously and consecutively eastward. Upon reaching the level of the lower crust, the tectonic sheets of the accretionary complex lose their distinct outlines. In the seismic reflection pattern they are replaced by a uniform acoustically translucent medium, where separate sheets can only be traced fragmentarily. The crust-mantle boundary bears a diffuse character: the transition from crust to mantle is recorded by the disappearance of the vaguely drawn boundaries of the tectonic sheets and in the gradual transition of acoustically homogeneous and translucent lower crust into transparent mantle. Under the effect of endogenic heat flow, the accretionary complex underwent high-temperature metamorphism and partial melting. Blurring of the rock contacts, which in the initial state created contrasts of acoustic impedance, was caused by partial melting and mixing of melts. The 3D model is used as a starting point for the evolutionary model of the Svecofennian Accretionary Orogen and for determination of its place in the history of the Palaeoproterozoic Lauro-Russian intracontinental orogeny, which encompassed a predominant part of the territory of Lauroscandia, a palaeocontinent combining North American and East European cratons. The model includes three stages in the evolution of the Lauro-Russian Orogen (~2.5, 2.2–2.1, and 1.95–1.87 Ga in age). The main feature of the Palaeoproterozoic evolution of the accretionary Svecofennian Orogen and Lauroscandia as a whole lay in the causal link with evolution of a superplume, which initiated plate-tectonic events. The Svecofennian–Pre-Labradorian palaeo-ocean originated in the superplume axial zone; the accretionary orogens were formed along both continental margins due to closure of the palaeo-ocean.
Key words: reflection seismics; magnetotellurics; Svecofennian accretionary orogen; Svecofennian ocean; 3D crustal model; velocity-density layering
... Using seismic tomography techniques, scientists decode the information contained in seismograms' squiggles to develop images of individual slices through the deep Earth. These images are used to understand not only the composition of Earth's interior, but also to help explain geologic mysteries like concealed structures, interstitial fluids, earthquake nucleation zones, composition of rocks at the crust-mantle transition, different types of crust-mantle boundary, as well as many other geological processes (see a review by [Zhao, 2001;Janik et al., 2007Janik et al., , 2009Janik, 2010]). The crustal and upper mantle structures beneath some parts in Anatolia have been studied recently by seismic tomography on different scales [e.g., Sandvol et al., 2001;Nakamura et al., 2002;Al-Lazki et al., 2003Bariş et al., 2005;Lei, Zhao, 2007;Salah et al., 2007Salah et al., , 2011Salah et al., , 2014aSchmid et al., 2008;Gans et al., 2009;Koulakov et al., 2010;Mutlu, Karabulut, 2011;Bakırcı et al., 2012;Warren et al., 2013]. ...
... After computing the P-and S-wave velocity models we calculated the V P /V S ratio at the different crustal layers. This ratio (or the Poisson's ratio) is more significant in characterizing the petrophysical properties of crustal rocks and provides better constraints on the crustal composition and interstitial fluids than the seismic wave velocities (e.g., [Christensen, 1996;Zhao et al., 2004;Bariş et al., 2005;Salah et al., 2007Salah et al., , 2011Janik, 2010]). Based on the NEIC (the National Earthquake Information Center, USGS) catalogs, we found a total of 12 moderate/large crustal events (M b or M w ≥5,0) that occurred in the study area since 1979. ...
... By present it has been reliably established that the Precambrian crust of the Fennoscandian 571 Shield, like of all continental domains, is characterized by near-horizontal density layering: the high- 572 velocity and high-density lower crust variable in thickness and depth occurs at base of the 573 Svecofennian Orogen and the adjacent tectonic subdivisions of regional rank 574 Bock et al., 2001;Bogdanova et al., 2006;Janik, 2010;Janutyte et al., 2014;Glaznev et al., 2015]. This 575 circumstance suggests that interpretation of composition and origin of the lower crust at the base of 576 Svecofennian Orogen should be comparable with similar characteristics at the base of neighboring 577 domains. ...
The results of this study are reported in two related successive publications. The article “3D model of the deep structure of the Svecofennian accretionary orogen based on data from CDP seismic reflection method, MT sounding and density modeling” (M. V. Mints, E. Yu. Sokolova, LADOGA Working Group) presented a 3D model of the deep structure of the Late Paleoproterozoic Svecofennian accretionary orogen. The model is based on harmonized data of geological mapping, FIRE-2-2a-1 and FIRE-3-3a seismic reflection profiling, using sections of the 3D crustal density model, results of magnetotelluric surveys along the Vyborg-Suojarvi profile in the Northern Ladoga area and materials from MT surveys previously carried out by Finnish specialists in Southern Finland. In this paper these results were used as the baseline for the construction of the evolutionary model and determination of the position of the Svecofennian orogen in the structure and history of the Paleoproterozoic Lauro-Russian intracontinental orogen. This Paleoproterozoic orogeny swept the predominant part of Lauroscandia, a paleocontinent that united the North American and the East European cratons. Interpretation of the structural features and evolution of the Lauro-Russian orogen leads to the conclusion that its onset and evolution had a causative relation to the development of the Paleoproterozoic superplume which, in turn, initiated plate tectonic events. The evolution of the Lauro-Russian orogen included three intensive development periods (~2.5; 2.2–2.1 and 1.95–1.87 Ga). In the axial zone of the intracontinental orogen there appeared the Svecofennian Pre-Labrador Ocean, and the accretionary Svecofennian and Pre-Labrador orogens formed along its continental margins after its closure.
... After determining the P-and S-wave velocity models, the Vp/Vs ratio can then be calculated in the modeling space. This ratio (or the Poisson's ratio) is a good indicator for the petrophysical properties of crustal rocks and can provide better constraints on the crustal composition and interstitial fluids than either P-or S-wave velocity alone [20][21][22][23][24][25]. So far, the Vp/Vs ratio has proved to be very significant in the understanding of the seismogenic behavior of the crust, and the role of crustal fluids in the nucleation and growth of earthquake rupture [2,23,[26][27][28][29]. ...
... Over the last few decades, the seismology of the Baltic region has been investigated in the framework of different international projects, for instance, SVEKOLAPKO et al. [Kozlovskaya et al., 2008]. The collected data have served as a basis for compilation of maps of seismic waves velocity distribution, Moho depth, and upper and lower crust thickness of a various degree of detail [Grad et al., 2009;Janik, 2010;Tesauro et al., 2010]. According to these data, crust thickness varies in the range of 38-40 km in the eastern part of the Gulf of Finland and the zone around the junction of the Gulf of Finland and the Bothnian Bay, reaching a level of 62 km in the south of Finland, and up to 47-50 km around the Kurzeme peninsula. ...
This study describes the experience of the application of computer technology \Structural
analysis of geophysical data" and geodynamic study results for the purpose of seismic
zoning of the region with a low seismic activity. In the Finnish{Bothnia region, including
the sea water area, a number of potential seismogenic zones were identi�ed. The results
can be used to compile the map of possible earthquake sources in the future
We present a modeling technique for generating synthetic ground motions, aimed at earthquakes of design significance for critical structures and ground motions at distances corresponding to the engineering near field, in which real data are often missing. We use dynamic modeling based on the finite-difference approach to simulate the rupture process within a fault, followed by kinematic modeling to generate the ground motions. The earthquake source ruptures were modeled using the 3D distinct element code (Itasca, 2013). We then used the complete synthetic program by Spudich and Xu (2002) to simulate the propagation of seismic waves and to obtain synthetic ground motions. In this work, we demonstrate the method covering the frequency ranges of engineering interests up to 25 Hz and quantify the differences in ground motion generated. We compare the synthetic ground motions for distances up to 30 km with a ground-motion prediction equation, which synthesizes the expected ground motion and its randomness based on observations. The synthetic ground motions can be used to supplement observations in the near field for seismic hazard analysis. We demonstrate the hybrid approach to one critical site in the Fennoscandian Shield, northern Europe.
Abstract
Project is devoted to development of the fundamental geological problem "Deep structure, origin and evolution of the crust and crust-mantle boundary of the Early Precambrian tectonic provinces". Geological and geophysical materials, including seismic profiling data of Canadian LITHOPROBE Program and Finnish FIRE project, were collected, systematized and analyzed. On this basis, the authors of the project first developed 3D models of the deep structure and formation history of the Archean crust of the North American craton, the Paleoproterozoic Svecofennian and Trans-Hudson Orogens, the Neoproterozoic Grenville Orogen, and the model of the Voronezh crystalline massif (VCM) was also improved. The materials of the deep crustal studies of the Australian craton are limited. The most important feature of the research methodology is the principle of feedback, which provides for mutual improvement: (1) information on the geological structure of the crust at the surface level of the shields or the surface of the basement beneath sedimentary cover, taking into account "deep" information, (2) geological interpretation of seismic images in deep crustal sections in inextricable connection with data on the geological structure at the erosion level. The base of the seismic images of the Early Precambrian crust and the crust-mantle boundary along the CDP profiles, which are crossing the territories of ancient cratons, has been significantly expanded. Comparison of the seismic images of the lower crust and the crust-mantle boundary at the base of ancient cratons made it possible to identify and characterize the structural-morphological types of the crust-mantle boundary and to connect their features with the geological structure and geological history of these cratons. It is shown: 1) seismic crustal images (seismic reflection patterns) demonstrate various elements of the tectonic structure of the crust and the crust-mantle boundary; 2) the subhorizontal velocity-density layering of the continental crust is superimposed on the previously formed geological structure, the density differentiation of rocks with depth decreases; the features of density layering are predominantly caused by the modern and relatively recent state of the crust, but may be violated as a result of the most recent deformations; 3) the high level of compaction of rocks in the crust under the influence of lithostatic loading can not be explained at the level of "simple" concepts of metamorphism and / or compaction of rocks based on laboratory studies of samples and computational models. This indicates the existence of additional and very powerful mechanisms, which provide reversible changes in rocks. Examples of the successful development of ideas about the structure and evolution of large Precambrian tectonic provinces are described, the basis of which is created by 3D models of the deep crustal structure:
1. North American composite craton: an oval-concentric tectonic-metamorphic zoning of the Archean lithosphere is revealed.
2. Superior Craton (one of the main components of the North American craton): an estimate of the location and significance of the Neo-Archaean accretionary complex and the formation of a lower crust with the participation of underplating and intraplating of mafic mantle magmas and granulite facies metamorphism;
3. Svecofennian accretionary orogen: the deep structure of the accretionary complex and the structure of the boundary zone of this complex with the Karelian craton have been deciphered, which significantly narrowed the scope of possible speculations about the history of the formation of this orogen.
4. Trans-Hudson intracontinental orogen: the deep structure has been deciphered, a combination of continental rifting processes in the western part of the orogen and the emergence of the ocean formation of accretionary complex similar to the Svecofennian one at the ocean closure.
5. East Voronezh Orogen: a 3D model of the deep structure presented a structure of the "crocodile" type and found the formation of a specific lower crustal structure formed when the short-lived linear ocean was closed.
In the future, the analysis of models of the deep structure and evolution of the Precambrian tectonic provinces opens up new possibilities for studying the genesis and geodynamic position of Precambrian ore formation processes. The sum of the models of individual tectonic provinces creates the basis for the development of integral models: Neoarchean-Proterozoic Supercontinent of Lauroscandia and the model of the evolution of the Atlantic Zone, which arose about 2.5 Ga ago and exists to the present day, and also to outline ways for explaining of the known differences in the metallogenic specifics of the North American and East European cratons during the Archean and Proterozoic.
