Abstract
We studied the spatial distribution of anomalies of the gravitational and the magnetic fields at the border between the Amur and the Eurasian plates. Methods of statistical analysis showed that the systems of anomalies of geophysical fields fit into the regular spatial structures and are controlled by lineaments of latitude, longitude and diagonal stretch, as well as zones of plastic-elastic flow of rocks (shear-zone). These facts allowed us to establish time of formation of the orthogonal system of geophysical fields anomalies in the strike azimuths (84-354 0 ). As a result of comparing diagonal system of geophysical fields anomalies with spatial distribution of the fields of contemporary seismicity and epicenters of strong earthquakes, an assumption was made that the diagonal system of lineaments fit into zones of tectonic deformation and has been controlling the epicentral fields of contemporary seismicity since the Mesozoic period of seismotectonic activation. The main result of this study is the synthesis of early scientific works and getting new ideas about the spatial distribution of anomalies of geophysical fields. Establishing the sequence of forming isolated systems of anomalies and relationships between geophysical fields and seismicity is the subject of further research.
Highlights
In course of geological study of the structure of the crust, the analysis of spatial distribution of geophysical fields anomalies is essential
Start of theoretical studies of the lineament structures and large-scale irregularities of the earth's crust has been given in works (Hobbs, 1904; Hubbert, 1937), which are being successfully developed at present with the use of new technologies for analyzing digital models, such as geophysical fields and landforms (Anokhin, Odessa, 2001; Arellano-Baeza et al, 2006; Anokhin, Maslow, 2009; Gilmanova et al, 2012; Loiane et al, 2014)
Comparative analysis of spatial distribution of earthquakes and the developed tectonics model of the Aldanian-Stanovoy megablock by statistical distribution of anomalies of geophysical fields has shown that the system of lineaments with azimuths (40 - 3100) fits into the structure of the seismic field, and all gravitate epicenters of strong earthquakes tend to the points formed by intersecting of lineaments of the system, or to axis lines (Figure 7)
Summary
In course of geological study of the structure of the crust, the analysis of spatial distribution of geophysical fields anomalies is essential. Most intensively the processes of reformation of the structural plan of spatial anomalies should occur in seismically active regions in the areas of interaction of tectonic plates and lineaments that divide them (Heleno C. et al, 2014). Due to this fact, there is a problem of determining the spatiotemporal relationships between systems of faults with different courses and, of determining periods of formation of geophysical fields anomalies. This work sets tasks of clarifying periods of formation of extended zones of geophysical anomalies by comparing these systems with spatial position of zones of elastic-viscous rocks flow (shear-zones) (Melnikov, 2008), and the tasks of finding patterns in distribution of spatial field of seismicity within the zone of interaction between the Amur and the Eurasian lithospheric plates
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