Vol 69 Iss. 2

The Pechenga-Allarechensk nickel structural zone of the Kola Peninsula is one of the few ore districts of the USSR, where ore seismic survey by the reflected wave method (RWM) for solving structural problems began to be applied for the first time and has been systematically carried out for a long time.....

Since 1970, a combined system of surface and borehole observations by reflected wave (RW) and vertical seismic profiling (VSP) methods has been successfully applied during detailed seismic work in the Pechenga region of the Kola Peninsula. ...

Since 1961, the reflected wave method (RWM) seismic survey has been successfully applied to study the Pechenga structure of the Baltic Shield. In the wave fields recorded in this area by systems of elongated travel-time curves, along with longitudinal P waves, intense direct transverse S waves are identified. This allows us to expect the recording of reflections of different types: longitudinal, transverse, and converted. When interpreting the wave field in these conditions, much attention is paid to determining the type of recorded waves. ...

When studying seismic exploration of ore areas, the velocity for the construction of reflecting boundaries cannot always be selected by methods developed in oil seismic exploration for horizontal layered media. This is due to the complexity of crystalline rock structures, intense tectonics and magmatism, which determine the regularities of elastic wave velocity distribution in sections of ore districts. The study of these regularities in connection with the geologic structure of the Pechenga region of the Baltic Shield allowed us to substantiate the method of velocity determination for the construction of reflecting boundaries on seismic sections of the Pechenga structure. ...

The Kafan mining district, within the limits of which exploration and exploitation of copper-molybdenum ore deposits are carried out, is most fully explored by prospecting and exploration works to a depth of 300-400 meters. The problem of increasing ore reserves in this area is closely connected with the need to increase the depth of exploration. In this connection, in 1971 the complex of geological and geophysical studies included seismic methods of exploration, the main task of which was to obtain data on the deep structure of structures controlling copper-molybdenum mineralization. ...

In recent years to solve a variety of geological and engineering-geological problems in the water areas of seas and water bodies are used sounding and seismic methods of exploration. They are mainly used to solve structural problems, but with the help of sound waves can be determined from the nature of reflected signals certain varieties of bottom sediments. ...

For the structural plan of the Precambrian, a wide development of so-called dome-shaped structures is very characteristic – gneiss-migmatite domes, in the central parts of which the most intensively granitized rocks are exposed. When mapping such structures, materials of airborne and ground magnetic surveys have been widely and successfully used in recent years. ...

One of the ways to improve the efficiency of geological exploration in the search for deep-seated ore bodies, especially under conditions of complex structures of ore fields, is the study of geophysical methods of the near-borehole and interwell space. In this case, the most widespread and developed are electrical exploration methods. ...

As a result of the gravity survey carried out by the West Geophysical Trust (WGT) in 1962, two anomalies were detected on the eastern shore of Lake Onega, which turned out to be associated with rocks of basic and ultrabasic composition, occupying an area of more than 1,000 km². The area of the anomalies was named the Burakovsko-Aganozerskaya zone of basic and ultrabasic rocks. ...

One of the main difficulties encountered by researchers in prospecting by geophysical methods for bauxite in the North Onega bauxite-bearing area is the poor contrast between sedimentary rocks in terms of physical properties. Commercial bauxite deposits are found here in the Lower Carboniferous. ...

Dipole inductive profiling with amplitude-phase measurements (DIP) has been successfully applied in the search for objects of high electrical conductivity. However, as follows from the laws of the electromagnetic field and the results obtained in field studies, the DIP method also can isolate and study objects that differ in magnetic permeability. ...

In the study of seismic exploration of complex geological areas successfully used developed in the USSR under the leadership of L.A. Ryabinkin method of adjustable directional reception (ADR), using one of the most common interference systems of wave separation. ...

Most of the methods allow the interpretation of gravity anomalies by the selection of masses without flexible connection with a priori data on their shape and density. Such an approach cannot be recognized as reasonable because of the uncertainty of the reference level and other reasons of ambiguity of the inverse problem of potential theory. In the framework of testing geologically based hypotheses about the shape and density of structures that are linked in advance to the observed anomalies, we propose, in our opinion, a more rational formulation of the problem. ...

Detailed geologic mapping of sedimentary rock strata based on ground magnetic survey data and solution of structural problems in the areas of their development is sharply limited until now. This is explained by the usually very low magnetization of sedimentary formations, their weak differentiation by magnetic properties and gentle bedding, which is characteristic of the territory under consideration. ...

Difficulties arising in detailed geological mapping of vast sodden and forested areas are in some cases successfully overcome by the application of geophysical methods. ...

The determining factor in the formation of the resulting anomalous curve over a complex electrically conductive zone is the distance between the individual layers composing the zone. In this case, depending on the distance, the main changes in the anomalous values, obviously, will occur at the points of the interval between the layers – places of the strongest mutual influence of neighboring layers. Therefore, it is sufficient to establish the regularities of these changes using the example of two strata. ...